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  • 1.
    Abrahamsson, Filip
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Leaching of Pyrrhotite from Nickel Concentrate2017Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Icke-oxidativ syralakning av magnetkis från Kevitsas Ni-koncentrat har studerats samt metoder för tillvaratagande av biprodukter. Genom en selektiv upplösning av magnetkis (Fe1-xS, 0<x<0.25) kan värdefulla metaller som Ni och Co anrikas i det slutliga koncentratet. Samtidigt som mängden Fe och S som skickas till smältverken minskar, vilket också innebär att mindre biprodukter i form av slagg och SO2 erhålls vid den pyrometallurgiska smältningen av Ni-koncentratet. En experimentell design plan genomfördes för att studera lakningen där syrakoncentrationen varierades från 38.8% till 57.8%H2SO4 och temperatur från 60 till 100°C. Bäst resultat erhölls vid de lägre parameterinställningarna. Lakning vid 60°C med en initial syrakoncentration på 38.8%H2SO4 visade sig vara tillräcklig för att selektivt lösa upp merparten av all magnetkis och lämna kvar en anrikad produkt. Via QUEMSCAN bekräftades att merparten av all magnetkis hade löst upp sig och att huvudsakligt Ni-mineral fortfarande var pentlandit. Kemiska analyser visade att mer än 95% av Ni, Co och Cu stannade kvar i fasta godset.

       Den tillämpade lakningsmetoden genererar biprodukter i form av stora mängder Fe2+ i lösning och H2S i gasform. För att tillvarata Fe2+ har kristallisering av laklösning som järn(ii) sulfat (FeSO4∙nH2O) studerats genom kylning. De kristalliserade kristallerna avvattnades till monohydrat, FeSO∙1H2O, genom avvattning i stark svavelsyra (80%H2SO4). XRD bekräftade FeSO∙1H2O som huvudfas i slutliga kristallerna och kemisk analys visade på ca 30%Fe med huvudsakliga orenheter i form av 1.5% Mg, 0.4%Ca och 0.2% Ni.

       Möjligheten till att laka i återcirkulerad lösning efter kristallisering har undersökts. Lakning i återcirkulerad lösning visade inga negativa effekter då liknande halter och utbyten erhölls till det fasta godset.

  • 2.
    Al-Douri, Yamur K.
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Hamodi, Hussan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Data imputing using generic algorithms (GA)2017Ingår i: Mine Planning and Equipment Selection (MPES 2017): Proceeding of the 26th International Symposium on Mine Planning and Equipment Selection Luleå, Sweden, August 29-31, 2017 / [ed] Behzad Ghodrati, Uday Kumar, Håkan Schunnesson, Luleå: Luleå tekniska universitet, 2017, s. 205-208Konferensbidrag (Refereegranskat)
  • 3.
    Ataide Salvador, Dandara
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Geometallurgical Variability Study of Spodumene Pegmatite Ores, Central Ostrobothnia - Finland2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This geometallurgical variability study was conducted for Keliber Oy definitive feasibility study. It includes the Syväjärvi, Länttä and Rapasaari lithium ore deposits located in Central Ostrobothnia – Finland. These deposits present different characteristics in terms of spodumene grade, grain size, alteration, and weathering.

    A geometallurgical approach was used to characterize the ore and learn about the variability within and between the deposits in terms of mineralogy and processing response. In the project design chosen, grinding and flotation tests were performed. In addition, chemical composition of spodumene, mineralogical and liberation studies were carried out by MLA and EDS analysis.

    Spodumene is the main Li mineral in the deposits and its characteristics and elemental composition differ between and within these deposits, affecting mineral processing behavior. Spodumene impurities content as FeO and MnO are the highest in Länttä and lowest in Rapasaari. With respect to the harmful elements, Mg is carried by amphiboles and micas and P by apatite and sicklerite.

    Grinding is mainly influenced by the spodumene grade of the ore. The total grinding time to reach the P80 target was similar for the average ores, around 30 minutes of two stage grinding. Pre-flotation removed more than 50% of the apatite with on average 4.6% losses of spodumene. A cleaning stage for the pre-flotation product is recommended to recover some of the spodumene losses.

    In spodumene flotation with rougher and seven cleaning stages, Syväjärvi average ore showed high recoveries (about 90%) to final concentrate, whereas Länttä and Rapasaari presented clearly lower recoveries, (about 70%). In addition, Länttä presented the lowest spodumene grade in the final concentrate (about 70%) and Rapasaari the highest (about 75%). The flotation process, in general, turned out to be efficient in terms of concentrate grade, achieving, in most of the cases, the targeted Li2O grade of 4.5%. Although, the geometallurgical test is based on flowsheet developed for Syväjärvi and it is quite expected that Länttä and Rapasaari samples show poorer performance. Therefore, flotation tests and process optimization should be done to improve the spodumene recovery of Länttä and Rapasaari deposits. Considering Syväjärvi samples, spodumene head grade and grain size had positive effects in flotation. In contrast, spodumene alteration had a negative effect. Länttä shows lower spodumene liberation with given grind which leads to lower recovery and grade in flotation. A combination of lower feed grade, locking association, P80 and secondary Li minerals may explain Rapasaari samples performance. The weathered Rapasaari sample showed a positive effect on spodumene recovery which is possibly due to the liberation of spodumene grains from feldspars and quartz. Controlled waste dilution on ore samples promoted lower spodumene recovery and lower final concentrate grades, proportional to the dilution ratio. The results indicate that flowsheet and processing conditions as P80 and collector dosage need to be optimized by the deposit and by the ore type. Nevertheless, the present study is a diagnostic test and the results cannot be directly correlated to full-scale process.

  • 4.
    Belo Fernandes, Ivan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Geometallurgical approach to understand how the variability in mineralogy at Zinkgruvan orebodies affects the need for copper activation in the bulk rougher-scavenger flotation2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Zinkgruvan is a Pb-Zn-Ag deposit located in south-central Sweden, owned and operated by Lundin Mining. The ore is beneficiated by a collective-selective flotation circuit, recovering both galena and sphalerite in a bulk rougher-scavenger flotation stage and later on separating them into two final products. Opportunities for increase in zinc recovery in the bulk rougher scavenger flotation stage have been identified as the plant is relying on natural Pb-activation to process the ore.

    Process mineralogical tools were used to characterize four different orebodies from Zinkgruvan (Burkland, Borta Bakom, Nygruvan and Sävsjön) and evaluate the metallurgical performance for flotation and magnetic separation, following a geometallurgical approach to better understand and predict the behavior of such ore types in processing plant.

    The first hypothesis in this thesis is that by addition of copper sulfate and increased collector dosage, Zn recovery will be improved without being detrimental to galena flotation. Results demonstrated that there is a significant increase in Zn recovery by further increasing collector dosage and copper-activating the flotation pulp in the scavenger stage. For instance, an increase in zinc recovery up to 16% has been achieved after addition of copper sulfate. Galena is readily floatable while sphalerite takes longer to be recovered. In addition, iron sulfides take longer to be recovered and, after addition of copper sulfate, there was an increase in iron sulfide recovery.

    The amount of iron sulfides reporting to the concentrate should still not be a problem to the plant. Most of the Fe in the concentrate is still coming from the sphalerite lattice. However, it might be that some orebodies coming into production in the near future have higher amounts of pyrrhotite, which might be a problem. Therefore, magnetic separation methods have been tested to remove pyrrhotite from the bulk ore. The second hypothesis is that the high Fe content in the concentrate might be due to the presence of iron sulfides, in which case they could be selectively removed by magnetic separation.

    XRD analyses demonstrated that Sävsjön is a highly variable orebody, and that its high Fe content varies with the location inside the orebody, being caused by either iron sulfide or iron oxide minerals. Both monoclinic and hexagonal pyrrhotite have been observed. Davis Tube could remove monoclinic pyrrhotite but it was very inefficient when dealing with hexagonal pyrrhotite. WHIMS, on the other hand, performed well for both types of pyrrhotite. When applying Davis Tube on Sävsjön OLD feed, a concentrate with up to 52.3% pyrrhotite is achieved, at a recovery of 35.32%. However, sphalerite is also reporting to the magnetic concentrate, which would generate Zn losses for the overall process. Zinc losses were up to 15.3% when the highest field strength was applied. Therefore, the applicability of magnetic separation for Zinkgruvan ore must be further evaluated.

  • 5.
    Bergkvist, Adam
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Mobil bergkrossning: Energibehov och emissioner2017Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I detta examensarbete undersöks energibehov och emissioner hos mobila krossanläggningar tillhörande NCC Industry AB. Bergtäkterna Eker och Dylta i Örebro län samt Mörtsjön i Södermanlands län har studerats och analyserats. Dessa bergtäkter producerar ballastprodukter som till större del används i anläggningsindustrin och vid asfaltstillverkning. Tester har genomförts på den elektriska konsumtionen i de olika anläggningarna för att beräkna relevanta parametrar som varit eftersökta. Produktionsrapporter och elmätningar har sammanställts, löpande under ett flertal veckor, i ett räknedokument för att kunna erhålla efterfrågade datavärden.

    De sökta faktorerna har varit energibehov i form av kWh/Ton samt emissioner i form av kg CO2/Ton. Mätningarna avser krossar, siktar och transportband vid maskinuppställningar för mobil krossning. Resultaten visar att värden på elförbrukningen uppgår till 2,1 kWh/ton med en variation från 1,1 till 3,1 kWh/ton beroende på ingående maskiner och driftförhållanden. För CO2-emissionerna var motsvarande genomsnitt 0,9 kg CO2/ton vid dieseldrift med variation 0,4 till 1,6 kg CO2/ton. Vid omräkning till en tänkt nätdrift med el låg genomsnittet på 0,17 kg CO2/ton. Beräkningarna skall bidra till en grönare tillverkningsprocess av ballastprodukter och kom att visa att skillnaderna i utsläpp (kg CO2/Ton) är uppemot 90 % större vid dieseldrift gentemot eldrift på en av de olika anläggningarna. Dessa resultat har sedan analyserats och rekommendationer görs för framtida drift och investeringar i samtliga anläggningar. Dessa rekommendationer utvärderas sedan av NCC för att avgöra huruvida de är relevanta eller icke. Att genomföra ombyggnationer och modifiera utrustningen kan dock vara mycket kostsamt. Elektricitetsproduktionen är inte analyserad i rapporten. Beräkningar är utförda med förutsättningen att elen är av nordisk mix. Dessa uppgifter är inhämtade från Naturvårdsverket. En ekonomisk analys av denna investering ingår inte i denna rapport. 

  • 6.
    Bertholdsson, Morgan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Utredning om dimension av kamjärnsbultar i Garpenbergsgruvan2018Självständigt arbete på grundnivå (yrkesexamen), 180 hpStudentuppsats (Examensarbete)
  • 7.
    Bertilsson, Olle
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Study of leaching behavior of tin in Zinc-clinker and Mixed Oxide2018Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Due to the increasing usage of Sn in different electronics, such as solders and in touchscreens, together with Boliden Rönnskärs increased intake of electronic waste as a secondaryraw material, a Zn-containing product called Zn-clinker has increasing amounts of Sn. TheZn-clinker is shipped to Boliden Zn-smelter in Odda, where the Zn-clinker is mixed in withcalcine (roasted concentrate) and leached in several steps. Since Zn-clinker is a product froma halogen removal in a clinker-furnace, the feed material (Mixed Oxide), for this furnace, wasalso investigated since there are plans to replace clinkering with soda-washing in the future.Most of the Sn ends up in the leaching residue which then is deposited in the mountaincaverns close by the Boliden Odda smelter. Boliden is studying the possibility to recoverPb/Ag and Sn content from the leaching residue and create a valuable by-product. Bystudying how the leaching of Sn behaves, together with a characterization of the materials, thefollowing question should be answered: “During which sulphuric acid leaching conditions, ofZn-clinker and Mixed Oxide, is the leaching of Sn minimized?”

    The leaching results for Zn-clinker showed that 8-10% Sn will leach out, despite changingtemperature, redox potential, time and pH. A characterization of the material with SEM-EDSand XRD-analysis was also conducted to see if Sn could be identified in any phases in thematerials. The studies provided enough evidence that Zn2SnO4 could be concluded to be themain phase in the leaching residue for Zn-clinker, a form that would not leach underconditions presented in this project. However, 8-10% of the Sn will come together with Feand when Fe leach out, so does Sn.

    The leaching results for Mixed Oxide pointed towards that different phases from them foundin Zn-clinker was present. Sn losses varied between 10-20% but raised to 47% whentemperature was changed to 80 °C during leaching. The SEM-EDS analysis showed that theidentified Sn-phases contained more Sn than in Zn-clinker and together with the leachingresults, a conclusion that Sn would mainly be found as SnO2 or SnO in the Mixed Oxide, butthere is still uncertainty about the distributions of these forms.

    Unfortunately half of the As leached out during the soda-washing for Mixed Oxide, creating aleachate with Cl, F and As that need to be taken care of. This could be challenging andpresenting a costly side-project for the route different from the Zn-clinker route used today.Another observation was that PbCO3 formed during the soda-washing, a phase that willconsume more sulphuric acid during leaching.

  • 8.
    Björnström, Albert
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Flödeskalibrering: Analys av kalibreringsprocesser2018Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I december 2015 undertecknades Parisavtalet i syfte att skapa ett bättre globalt klimat. Enligt avtalet ska alla länders utsläpp redovisas till FN. En förutsättning för att Sverige ska kunna redovisa utsläppen är att nuvarande utsläppsnivåer är kända, varför mätning och beräkning av utsläpp är nödvändig.

     

    Det statligt ägda gruvbolaget Luossavaara Kiirunavaara AB (LKAB) driver järnmalmsgruvor i Malmfälten. Den järnmalmspellets som tillverkas vid kulsinterverket KK4 i Kiruna består till viss del av tillsatsmedel, som vid förbränning bildar koldioxid. Hur mycket tillsatsmedel som förbränns mäts med hjälp av två flödesmätare. För att säkerställa att dessa mätare har godkänd noggrannhet utförs årliga kalibreringar där uppmätt volym jämförs med en referensvolym. I syfte att säkerställa att LKAB:s kalibreringsmetod fungerar har ett externt företag utfört kalibrering med en annan metod där mätsensorer placeras på tillsatsmedelledningen. Resultaten mellan de två kalibreringsmetoderna skiljer sig avsevärt, vilket föranlett denna rapport.

     

    Syftet med arbetet är att ta fram förbättringsåtgärder för LKAB:s kalibreringsmetod samt presentera förslag på hur LKAB kan skapa bättre förutsättningar för den andra så kallade pulshastighetsmetoden. Genom att analysera respektive kalibreringsmetod och utföra mätningar, tester och beräkningar tas svagheter fram. Tester visar att en svaghet med LKAB:s kalibrering är att den nivåmätningsmetod som används är personberoende. Nivåmätning med laseravståndsmätare testas med gott resultat varför denna typ av mätning rekommenderas framöver.

     

    En svaghet med pulshastigheten är att den är känslig för variation av rörens innerdiameter. För att denna metod ska ge tillförlitliga resultat krävs ombyggnation av ledningar samt noga uppmätt innerdiameter.

     

    Noggrann flödesmätning leder till att nuvarande koldioxidutsläpp kan beräknas vilket skapar förutsättningar för fortsatt arbete mot uppställda miljömål. Flödesmätarna har även en betydande roll för produktkvaliteten i KK4 vilket innebär att denna rapport kan bidra till högre kvalitet och ekonomisk lönsamhet.

  • 9.
    Chelgani, Saeed Chehreh
    et al.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Dehghan, F.
    Department of Computer engineering, Jajarm Branch, Islamic Azad University, Iran.
    Hower, J. C.
    Center for Applied Energy Research, University of Kentucky, USA.
    Estimation of some coal parameters depending on petrographic and inorganic analyses by using Genetic algorithm and adaptive neuro-fuzzy inference systems2011Ingår i: Energy Exploration and Exploitation, ISSN 01445987, Vol. 29, nr 4, s. 479-494Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Adaptive neuro-fuzzy inference systems (ANFIS) in combination with genetic algorithm (GA); provide valuable modeling approaches of complex systems for a wide range of coal samples. Evaluation of this combination (GA-ANFIS) showed that the GA-ANFIS approach can be utilized as an efficient tool for describing and estimating some of coal variables such as Hardgrove grindability index, gross calorific value, free swelling index, and maximum vitrinite reflectance with various coal analyses (proximate, ultimate, elemental, and petrographic analysis). Statistical factors (correlation coefficient, mean square error, and variance accounted for) and differences between actual and predicted values demonstrated that the GA-ANFIS can be applied successfully, and provide high accuracy for prediction of those coal variables.

  • 10.
    Chelgani, Saeed Chehreh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Hadavandi, Esmaeil
    Department of Industrial Engineering, Birjand University of Technology, Birjand, Iran.
    Hower, James C.
    Center for Applied Energy Research, University of Kentucky, Lexington, KY, USA.
    Estimation of heavy and light rare earth elements of coal by intelligent methods2019Ingår i: Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, ISSN 1556-7036, E-ISSN 1556-7230Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Since last two decades, several investigations in various countries have been started to discover new rare earth element (REE) resources. It was reported that coal can be considered as a possible source of them. REE of coal occur in low concentrations, and their detection is a complicated process; therefore, their predictions based on conventional coal properties (proximate, ultimate and major elements (ME)) may have several advantages. However, few studies have been conducted in this area. This study examined relationships between coal properties and REE (HREE and LREE) for a wide range of coal samples (708 samples). Variable importance measure (VIM) by Mutual information (MI) as a new feature selection method was applied to consider the heterogeneous structure of coal and assess the individual relation between coal parameters and REE to select the compact subsets as input variables for modeling and improve the performance of prediction. VIM by MI showed that Si-Carbon, and Al-Hydrogen are the best subsets for the prediction of HREE and LREE concentrations, respectively. A boosted neural network (BNN) model as a new predictive tool was used for REE prediction. BNN can significantly reduce generalization of error. Results of BNN models showed that the HREE and LREE concentrations can satisfactory estimate (R 2 : 0.83 and 0.89, respectively). Results of this investigation were approved that MI-BNN can be used as a potential tool for prediction of other complex problems in energy and fuel areas.

  • 11.
    Chelgani, Saeed Chehreh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Surface Science Western, Research Park, University of Western Ontario, Canada.
    Hart, B.
    Surface Science Western, Research Park, University of Western Ontario, Candada.
    Grady, W. C.
    West Virginia Geological and Economic Survey, USA.
    Hower, J. C.
    Center for Applied Energy Research, University ofKentucky, USA.
    Study relationship between inorganic and organic coal analysis with gross calorific value by multiple regression and ANFIS2011Ingår i: International Journal of Coal Preparation and Utilization, ISSN 1939-2699, Vol. 31, nr 1, s. 9-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The relationship between maceral content plus mineral matter and gross calorific value (GCV) for a wide range of West Virginia coal samples (from 6518 to 15330 BTU/lb; 15.16 to 35.66 MJ/kg) has been investigated by multivariable regression and adaptive neuro-fuzzy inference system (ANFIS). The stepwise least square mathematical method comparison between liptinite, vitrinite, plus mineral matter as input data sets with measured GCV reported a nonlinear correlation coefficient (R 2) of 0.83. Using the same data set the correlation between the predicted GCV from the ANFIS model and the actual GCV reported a R 2 value of 0.96. It was determined that the GCV-based prediction methods, as used in this article, can provide a reasonable estimation of GCV.

  • 12.
    Chelgani, Saeed Chehreh
    et al.
    Surface Science Western, Research Park, University of Western Ontario, Canada.
    Hart, B.
    Surface Science Western, Research Park, University of Western Ontario, Candada.
    Marois, J.
    Niobec Inc., Canada.
    Ourriban, M.
    Niobec Inc., Canada.
    Study of pyrochlore matrix composition effects on froth flotation by SEM-EDX2012Ingår i: Minerals Engineering, ISSN 0892-6875, Vol. 30, s. 62-66Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM–EDX) was used to analyse pyrochlore grains from Niobec froth flotation plant. Approximately 200 pyrochlore gains from the mill feed, pyrochlore rougher feed, pyrochlore rougher concentrate, and tail were analysed in order to identify a potential relationship between pyrochlore matrix composition and selective separation. Analyses indicate that pyrochlore grains with high Fe content appear to be less recoverable than those with a lower Fe content. Furthermore, analysis indicates that the flotation response is related to matrix Fe rather than Fe occurring as inclusions within the pyrochlore. These mineralogical investigation results are from a much larger program where pyrochlore matrix composition will be examined in relation to surface chemistry and flotation selectivity.

  • 13.
    Chelgani, Saeed Chehreh
    et al.
    Surface Science Western, Research Park, University of Western Ontario, Canada.
    Hart, B.
    Surface Science Western, Research Park, University of Western Ontario, Candada.
    Marois, J.
    Niobec Inc., Canada.
    Ourriban, M.
    Niobec Inc., Canada.
    Study of pyrochlore surface chemistry effects on collector adsorption by TOF-SIMS2012Ingår i: Minerals Engineering, ISSN 0892-6875, Vol. 39, s. 71-76Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Time of flight secondary ion mass spectrometry (TOF-SIMS) was used to analyse the surface of two different types of pyrochlore, high Fe pyrochlore and low Fe pyrochlore, from Niobec Saint-Honore mine deposit. Pyrochlore grains were analysed in order to identify a potential relationship between pyrochlore matrix composition, the corresponding surface expression and the related effect on cationic collector adsorption. TOF-SIMS analyses of pyrochlore surfaces from a conditioning test show that the species indicative of the cationic collector, favour the surface of Fe poor pyrochlore relative to the Fe rich variety. Lower collector signals on the surface of the Fe-pyrochlore are matched by higher relative intensities of Fe, OH, O and FeOH. The TOF-SIMS results illustrate a negative relationship between a cationic collector adsorption and the presence of Fe and Fe oxidation species on the surface of pyrochlore grains, and supports previous work which identified a negative correlation between matrix Fe content and pyrochlore floatability. The surface analysis illustrates the link between pyrochlore matrix chemistry, the expression of surface species and their effect on collector adsorption.

  • 14.
    Chelgani, Saeed Chehreh
    et al.
    Surface Science Western, Research Park, University of Western Ontario, Canada.
    Hart, B.
    Surface Science Western, Research Park, University of Western Ontario, Candada.
    Marois, J.
    Niobec Inc., Canada.
    Ourriban, M.
    Niobec Inc., Canada.
    Study the relationship between the compositional zoning of high iron content pyrochlore and adsorption of cationic collector2013Ingår i: Minerals Engineering, ISSN 0892-6875, Vol. 46-47, s. 34-37Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The matrix composition and surface chemistry of high iron pyrochlore (Fe pyrochlore) grains from Niobec (St-Horone carbonatite deposit) were analyzed, in order to identify a potential relationship between Fe pyrochlore matrix composition and the related effect on cationic collector adsorption (tallow diamine). SEM–EDX analyses indicate compositional zoning in the structure Fe pyrochlores. TOF-SIMS was used to analyse the surface of different compositional zones of Fe pyrochlore, in order to identify their related effects on tallow diamine adsorption. Surface analyses of high and low iron zones of treated Fe pyrochlore show that species indicative of the collector favour the regions of low iron content The low iron areas also show a lower relative proportion of species indicative of oxidation. This study identifies the link between Fe pyrochlore compositional zoning, surface oxidation and, area selective collector loading.

  • 15.
    Chelgani, Saeed Chehreh
    et al.
    Surface Science Western, University of Western Ontario, Canada.
    Hower, J. C.
    Center for Applied Energy Research, University of Kentucky, USA.
    Hart, B.
    Surface Science Western, University of Western Ontario, Canada.
    Estimation of free-swelling index based on coal analysis using multivariable regression and artificial neural network2011Ingår i: Fuel Processing Technology, ISSN 0378-3820, Vol. 92, nr 3, s. 349-355Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of proximate, ultimate and elemental analysis for a wide range of American coal samples on Free-swelling Index (FSI) have been investigated by multivariable regression and artificial neural network methods (ANN). The stepwise least square mathematical method shows that variables of ultimate analysis are better predictors than those from proximate analysis. The non linear multivariable regression, correlation coefficients (R2) from ultimate analysis inputs was 0.71, and for proximate analysis input variables was 0.49. With the same input sets, feed-forward artificial neural network (FANN) procedures improved accuracy of predicted FSI with R2 = 0.89, and 0.94 for proximate and ultimate analyses, respectively. The ANN based prediction method, as a first report, shows FSI is a predictable variable, and ANN can be further employed as a reliable and accurate method in the free-swelling index prediction.

  • 16.
    Chelgani, Saeed Chehreh
    et al.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Hower, J. C.
    Center for Applied Energy Research, University of Kentucky, USA.
    Jorjani, E.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Mesroghli, Sh.
    Department of Mining Engineering, Research and Science Campus, Islamic Azad University, Iran.
    Bagherieh, A. H.
    Department of Mining Engineering, Research and Science Campus, Islamic Azad University, Iran.
    Prediction of coal grindability based on petrography, proximate and ultimate analysis using multiple regression and artificial neural network models2008Ingår i: Fuel Processing Technology, ISSN 0378-3820, Vol. 89, nr 1, s. 13-20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of proximate and ultimate analysis, maceral content, and coal rank (Rmax) for a wide range of Kentucky coal samples from calorific value of 4320 to 14960 (BTU/lb) (10.05 to 34.80 MJ/kg) on Hardgrove Grindability Index (HGI) have been investigated by multivariable regression and artificial neural network methods (ANN). The stepwise least square mathematical method shows that the relationship between (a) Moisture, ash, volatile matter, and total sulfur; (b) ln (total sulfur), hydrogen, ash, ln ((oxygen + nitrogen)/carbon) and moisture; (c) ln (exinite), semifusinite, micrinite, macrinite, resinite, and Rmax input sets with HGI in linear condition can achieve the correlation coefficients (R2) of 0.77, 0.75, and 0.81, respectively. The ANN, which adequately recognized the characteristics of the coal samples, can predict HGI with correlation coefficients of 0.89, 0.89 and 0.95 respectively in testing process. It was determined that ln (exinite), semifusinite, micrinite, macrinite, resinite, and Rmax can be used as the best predictor for the estimation of HGI on multivariable regression (R2 = 0.81) and also artificial neural network methods (R2 = 0.95). The ANN based prediction method, as used in this paper, can be further employed as a reliable and accurate method, in the hardgrove grindability index prediction.

  • 17.
    Chelgani, Saeed Chehreh
    et al.
    Department of Mining Engineering, Science and Research Branch, Islamic Azad University, Iran.
    Jorjani, E.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Microwave irradiation pretreatment and peroxyacetic acid desulfurization of coal and application of GRNN simultaneous predictor2011Ingår i: Fuel, ISSN 0016-2361, Vol. 90, nr 11, s. 3156-3163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Artificial neural network was used to predict the effects of operational parameters on coal desulfurization using peroxyacetic acid from microwave pretreated coal. Coal particle size (150–1125 μm), leaching temperature (25–85 °C), leaching time (0–120 min), microwave irradiation power (0–1000 W) and time (0–110 s) were used as inputs to the network. The outputs of the model were organic and inorganic sulfur reductions for 40 of the data sets. The GRNN artificial neural network with spread of 0.3 was used to estimate both organic and inorganic sulfur reduction from a combined database, which was established from microwave pretreatment and leaching experiments. Thirty-two data sets were used for training and eight data sets for testing. Simulated values obtained from the neural network, correspond closely to the experimental results. Satisfactory correlations of R2 = 0.99 and 0.97 were achieved during the testing stages of the prediction of inorganic and organic sulfur reductions respectively.

  • 18.
    Chelgani, Saeed Chehreh
    et al.
    Surface Science Western, Research Park, University of Western Ontario, Canada.
    Makaremi, S.
    Biomedical Engineering Graduate Program, University of Western Ontario, Canada.
    Explaining the relationship between common coal analyses and Afghan coal parameters using statistical modeling methods2013Ingår i: Fuel Processing Technology, ISSN 0378-3820, Vol. 110, s. 79-85Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigates the effects of proximate, ultimate and elemental analysis for Afghan coal samples on Hardgrove grindability index (HGI), Gross calorific value (GCV), and Ash fusion temperatures (AFTs) by using multivariable regression (MR) and Adaptive neuro-fuzzy inference system (ANFIS) to increase information about the properties of the Afghan coal. Statistical modeling (MR, and ANFIS) indicated that coal parameters (HGI, GCV, AFTs) can be predicted with high accuracy, where GCV, AFTs, and HGI were estimated by R2 = 0.99, 0.95, and 0.94, respectively. The small difference between the estimated parameters and their actual values shows that these accurate results can be also applied to estimate coal properties in other coal resources of Afghanistan.

  • 19.
    Chelgani, Saeed Chehreh
    et al.
    Surface Science Western, University of Western Ontario, Canada.
    Mesroghli, S.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University, Iran.
    Hower, J. C.
    Center for Applied Energy Research, University of Kentucky, USA.
    Simultaneous prediction of coal rank parameters based on ultimate analysis using regression and artificial neural network2010Ingår i: International Journal of Coal Geology, ISSN 0166-5162, Vol. 83, nr 1, s. 31-34Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Results from ultimate analysis, proximate and petrographic analyses of a wide range of Kentucky coal samples were used to predict coal rank parameters (vitrinite maximum reflectance (Rmax) and gross calorific value (GCV)) using multivariable regression and artificial neural network (ANN) methods. Volatile matter, carbon, total sulfur, hydrogen and oxygen were used to predict both Rmax and GCV by regression and ANN. Multivariable regression equations to predict Rmax and GCV showed R2 = 0.77 and 0.69, respectively. Results from the ANN method with a 2–5–4–2 arrangement that simultaneously predicts GCV and Rmax showed R2 values of 0.84 and 0.90, respectively, for an independent test data set. The artificial neural network method can be appropriately used to predict Rmax and GCV when regression results do not have high accuracy.

  • 20.
    Danielsson, Markus
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ghosh, Rajib
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Navarro Miguel, J.
    Universidad Politechnica de Madrid.
    Johansson, Daniel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Schunnesson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Utilizing production data to predict operational disturbances in sublevel caving2017Ingår i: Mine Planning and Equipment Selection (MPES 2017): Proceeding of the 26th International Symposium on Mine Planning and Equipment Selection Luleå, Sweden, August 29-31, 2017 / [ed] Behzad Ghodrati, Uday Kumar, Håkan Schunnesson, Luleå: Luleå tekniska universitet, 2017, s. 139-144Konferensbidrag (Refereegranskat)
  • 21.
    de Groot, Laura
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Studie av omskjutningar i tunneldrivningsprojekt2017Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Conventional drill and blast tunnelling consists of mainly seven elements which together makes a cycle. This cycle includes drilling and blasting which are crucial factors in tunnelling projects, as these have a major influence on how the project will progress. After blasting there can be occurrences of under-break with so called bootholes in it and a re-blast is needed. This is expensive and time-consuming, and is therefore indefensible due to causing extra costs as well as a delay in the completion of the whole project. A solution for this problem is needed to avoid blasting second times.

    Due to laws regulating the allowed fracture zone in tunnel-blasting, contour blasting is performed. The reason behind why bootlegs emerges after blasting is still unknown and depends on many varied factors, such as geology, blast pattern and the volume of explosives used. Different tests are done while blasting, thereafter the results are evaluated and documented. Each test was tried three times to get as a most reliable result as possible. Among others the amount of explosives ranged, double detonators in poor rock sections and a new drill plan was made.

    The main theory behind this project was that the problem with bootlegs mainly depended om poor geological situations in the rock. None of the test however have been successful enough to solve the problem and after almost every blast there where bootholes in the remaining rock. Recommendations for further testing are using a less amount of explosives as this was a successful method in Björkdalsgruvan in northern Sweden. Another thing worth giving a try is to remove the “helping-row” because it seems like it is breaking the contour-row and not doing any difference.

  • 22.
    DEHGHAN, S.
    et al.
    Mining Engineering Department, Mahallat Branch, Islamic Azad University, Iran.
    SATTARI, G.
    Mining Engineering Department, Mahallat Branch, Islamic Azad University, Iran.
    Chelgani, Saeed Chehreh
    Surface Science Western, University of Western Ontario, Canada.
    ALIABADI, M.A.
    Mining Engineering Department, Mahallat Branch, Islamic Azad University, Iran.
    Prediction of uniaxial compressive strength and modulus of elasticity for Travertine samples using regression and artificial neural networks2010Ingår i: Mining Science and Technology, ISSN 1674-5264, Vol. 20, nr 1, s. 41-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Uniaxial Compressive Strength (UCS) and modulus of elasticity (E) are the most important rock parameters required and determined for rock mechanical studies in most civil and mining projects. In this study, two mathematical methods, regression analysis and Artificial Neural Networks (ANNs), were used to predict the uniaxial compressive strength and modulus of elasticity. The P-wave velocity, the point load index, the Schmidt hammer rebound number and porosity were used as inputs for both methods. The regression equations show that the relationship between P-wave velocity, point load index, Schmidt hammer rebound number and the porosity input sets with uniaxial compressive strength and modulus of elasticity under conditions of linear relations obtained coefficients of determination of (R2) of 0.64 and 0.56, respectively. ANNs were used to improve the regression results. The generalized regression and feed forward neural networks with two outputs (UCS and E) improved the coefficients of determination to more acceptable levels of 0.86 and 0.92 for UCS and to 0.77 and 0.82 for E. The results show that the proposed ANN methods could be applied as a new acceptable method for the prediction of uniaxial compressive strength and modulus of elasticity of intact rocks.

  • 23.
    Gan, Princess Rochelle
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Flotation of Yxsjöberg historical tungsten ore tailings2019Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Tailings dams, due to their sheer size and metal content, pose safety and environmental hazards. The Småltjarnen repository, which hosts material from the largest known tungsten mineralization in Sweden named the Yxsjöberg deposit, is estimated to contain 2.2 million tons of material from previous operations when recovery rates of scheelite, chalcopyrite, and fluorite were low. The repository is also observed to contain at least four of the listed critical raw materials by the European Commission in 2017, namely tungsten, fluorite, beryllium, and bismuth. The amenability of this tailings repository as secondary sources for valuable minerals and metals supports the Raw Material Initiative and the drive of the European Union towards a more circular economy. This masters thesis is part of the REMinE (Improve Resource Efficiency and Minimize Environmental Footprint) project that aims to evaluate the amenability of historical mining waste for re-processing from the technical, economical, and environmental perspectives. The study focuses on work package 3 of the project: Identification of new processing methods for mine waste. Previous work on this repository includes geochemical characterization and physical separation through magnetic and gravity separation tests. Since scheelite, the main mineral of the deposit, is commonly recovered through combinations of gravity separation and flotation methods, it is imperative to investigate the response of the material to flotation tests. Further characterization work and flotation tests were rendered on samples from sampling location 6 (60°02'33.6"N 14°46'30.8"E). Previous work was done on samples from and near sampling location 1, which is southwest from location 6. Characterization methods performed on the material included elemental analysis through ICP-SFMS, X-ray diffraction measurements, and mineral liberation analysis as well as physical characterization through particle size distribution analysis and determination of specific gravity. Based on MLA, the material from the main samples showed good liberation by free surface which is important for flotation processes. Mineral association also showed low percentages between scheelite and other Ca-bearing minerals which is a main concern for scheelite flotation. Comparison of characterization work between the two sampling locations allows information on the repository at a larger scope. The common scheelite flotation collector sodium oleate, as well as novel formulations Atrac 2600 and Berol 8313 from Nouryon were tested in combination with the depressant sodium silicate. Based on mass recovery, grade and recovery, selectivity, required dosage, and the degree to which it is environmentally safe, Atrac 2600 at 400 g/t is deemed to produce the most positive results. Based on characterization of the material and flotation tests, an estimated 222,200 tons of -75 µm can go directly into the flotation circuit with an average grade of 0.2768% WO3 and 0.195% Cu. Approximately 15,000 tons at 0.50% WO3 and 14,000 tons at 0.224% Cu can be recovered at a single flotation. Rough mass balance of the process flowsheet indicates a Cu concentrate at 30% Cu will produce 880.50 tons, while a saleable scheelite concentrate at 65% WO3 will yield 672.16 tons from only the original -75 µm fraction of the material. Including the gravity separation tails intended to join the flotation circuit after grinding, an estimated 1,205.54 tons of scheelite at 65% WO3 and 1.860.20 tons of 30% Cu concentrate can be produced. Aside from this, the gravity separation circuit will still be able to yield 188,000 tons of 0.92% WO3 concentrate, which can be further studied if it can be beneficiated to a saleable product. Value estimation of the products for the recommended flowsheet indicate a total of US$ 17 million for the WO3 and Cu concentrates to be produced from the readily amenable -75 µm fraction to be treated directly by flotation. Inclusion of the gravity separation tails mass into the flotation feed yields a value estimated at US$32 million.

  • 24.
    Ghodrati, Behzad
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Kumar, UdayLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.Schunnesson, HåkanLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Proceeding of the 26th International Symposium on Mine Planning and Equipment Selection: MPES 20172017Proceedings (redaktörskap) (Refereegranskat)
  • 25.
    Ghosh, Rajib
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Assessment of rock mass quality and its effects on charge ability using drill monitoring technique2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    For an efficient mining operation, it is essential to have as much information as possible aboutthe ore to be excavated and the rock masses surrounding the ore. Geological information andthe content and distribution of extractable minerals, are central concerns for long term mineplanning. However, for mine stability and production scheduling, the mechanical conditionsof ore and side rock are also very important. The underground mining process normallyconsists of a number of unit operations, such as drilling, charging, blasting, loading,transportation, hoisting etc., linked in a production chain. The quality of the initial operations(drilling, charging and blasting) normally defines the pre-conditions for the following loadingand transportation processes in the mine. The ability to fully charge holes as planned has beenidentified as one of the major obstacles for smooth fragmentation. Course or unevenfragmentation will, for example, significantly affect the loading and transportation efficiencyin the downstream production chain.Earlier studies in LKAB’s Malmberget mine have shown that the chargeability is on averagearound 90%. However, individual levels can have an average chargeability of only 70% andindividual rings, at those levels, can suffer from chargeability as low as 50%. A significantpart of these problems has its origin in geo-mechanical problems in the rock mass. Therefore,detailed knowledge of the rock mass condition surrounding the boreholes is essential toimprove the planning and execution of the charging works in a mine and to improve overallfragmentation and production efficiency.The focus of this thesis is therefore to define and evaluate geo-mechanical features in thedrilled rock mass effecting chargeability, and to evaluate drill monitoring technique for theassessment of rock mass quality and its effects on borehole’s chargeability using hydraulic In-The-Hole (ITH) percussive drilling.The research is based on literature review, drill-monitoring data, borehole filming, on-lineproduction database and monitoring of charging operation. Statistical methods are used toanalyse drill data. The data have been collected from LKAB’s underground mine inMalmberget, Sweden.Several rock mass conditions including caving, shearing, deformation, fracturing, cavities,solid rock, etc., have been identified during filming of 361 production boreholes.Measurement While Drilling (MWD) technique has been used to assess the quality of thepenetrated rock mass. In order to do so, a detailed analysis of the drilling system and thedrilling control including how monitored parameters relate to each other and to the penetratedrock mass conditions, has been performed. The results show that the MWD data containpronounced hole length dependent trends, both linear and step-wise linear, for mostparameters. By combining the borehole filming and the analyses of monitored drillparameters, the drilling responds to each geo-mechanical features in the rock mass is furtherdemonstrated. High correlation has been found between the geo-mechanical rock properties(fractures, cavities, solid rocks, etc.,), and the registered drilling system’s response. Theanalyses show that the responses from the drill monitoring system can distinguish between solid rock, fracture zone, cavity and cave-in. Based on the correlation between the registereddrilling system’s responses and the geo-mechanical features, a geo-mechanical model isdeveloped to assess the borehole chargeability. Principal Component Analysis (PCA) isperformed to model this relationship. The developed model can distinguish fans, or parts offans, with solid, non-fractured rocks where no chargeability problems can be expected, fromfans, or part of fans, with fractures, cavities or cave-in risks, where chargeability problemscan be expected. The model shows high potential for identifying charging problems in theborehole, and has been verified and validated by following an actual charging operation in thereal production environment.

  • 26.
    Ghosh, Rajib
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Schunnesson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Gustafson, Anna
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Monitoring of Drill System Behavior for Water-Powered in-the-hole (ITH) drilling2017Ingår i: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, nr 7, artikel-id 121Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A detailed understanding of the drilling system and the drilling control is required to correctly interpret rock mass conditions based on monitored drilling data. This paper analyses data from hydraulic in-the-hole (ITH) drills used in LKAB’s Malmberget mine in Sweden. Drill parameters, including penetration rate, percussive pressure, feed pressure, and rotation pressure, are monitored in underground production holes. Calculated parameters, penetration rate variability, rotation pressure variability, and fracturing are included in the analysis to improve the opportunity to predict rock mass conditions. Principal component analysis (PCA) is used to address non-linearity and variable interactions. The results show that the data contain pronounced hole length-dependent trends, both linear and step-wise linear, for most parameters. It is also suggested that monitoring can be an efficient way to optimize target values for drill parameters, as demonstrated for feed force. Finally, principal component analysis can be used to transfer a number of drill parameters into single components with a more straightforward geomechanical meaning

  • 27.
    Golshani, T.
    et al.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Jorjani, E.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Chelgani, Saeed Chehreh
    Young Researchers and Elites club, Science and Research Branch, Islamic Azad University, Iran.
    Shafaei, S. Z.
    School of Mining Engineering, University of Tehran, Iran.
    Nafechi, Y. H.
    epartment of Mining Engineering, Science and Research Branch, Islamic Azad University.
    Modeling and process optimization for microbial desulfurization of coal by using a two-level full factorial design2013Ingår i: International Journal of Mining Science and Technology, ISSN 2095-2686, Vol. 23, nr 2, s. 261-265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The microbial sulfur removal was investigated on high sulfur content (1.9%) coal concentrate from Tabas coal preparation plant. A mixed culture of ferrooxidans microorganisms was isolated from the tailing dam of the plant. Full factorial method was used to design laboratory test and to evaluate the effects of pH, particle size, iron sulfate concentration, pulp density, and bioleaching time on sulfur reduction. Statistical analyses of experimental data were considered and showed increases of pH and particle size had negative effects on sulfur reduction, whereas increases of pulp density and bioleaching time raised microbial desulfurization rate. According to results of designing, and regarding statistical factors, the optimum values for maximum sulfur reduction were obtained; pH (1.5), particle size (−180 μm), iron sulfate concentration (2.7 mmol/L), pulp density (10%) and bioleaching time (14 d), which leaded to 51.5% reduction from the total sulfur of sample.

  • 28.
    Guiral Vega, Juan Sebastian
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Textural and Mineralogical Characterization of Li-pegmatite Deposit: Using Microanalytical and Image Analysis to Link Micro and Macro Properties of Spodumene in Drill Cores.: Keliber Lithium Project, Finland.2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Lithium represents one of the strategic elements for the rest of the 21st century due to its increasing demand in technological applications. Therefore, new efforts should be focused on the optimization of mineral characterization processes, which link the ore properties with its behaviour during downstream processes. These efforts should result in reducing operational risks and increasing resources utilization. The methodology presented in this study is based on the application of several classification techniques, aiming the mineral and textural characterization of two spodumene pegmatite deposits within the Keliber Lithium Project.

    Twelve textural classes have been proposed for the textual classification of the ore, which have been defined through the recognition of the main mineral features at macro- and micro-scale. The textural classification was performed through the application of drill core logging and scanning electron microscopy. Six classes are proposed to describe the characteristics of the spodumene ore. Six additional classes describe the main properties of the rocks surrounding the ore zone.

    Image analysis was implemented for the generation of mineral maps and the subsequent quantification of spodumene and Li2O within the analysed drill core images. The image segmentation process was executed in Fiji-ImageJ and is based on eight mineral classes and a set of seven feature extraction procedures. Thus, quantification of spodumene and Li2O is estimated by textural class. Hyperspectral images were used as a reference for assessing the estimations made through images analysis.

    A machine learning model in Weka allowed forecasting the behaviour of the twelve textural classes during spodumene flotation. This model is fed by metallurgical data from previous flotation tests and uses Random Forest classifier.

    The proposed methodology serves as an inexpensive but powerful approach for the complete textural characterization of the ore at Keliber Lithium Project. It provides information about: (1) mineral features at different scales, (2) spatial distribution of textures within the pegmatite body, (3) quantification of spodumene and Li2O within the drill cores and (4) processing response of each textural class. However, its application requires wide knowledge and expertise in the mineralogy of the studied deposits.

  • 29.
    Haglund, Elin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Fukthaltens påverkan på maskintillverkad betongsand vid Vikan Kross2016Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I detta examensarbete undersöks hur fukthalten i det ingående materialet samt hastighetsinställningen på VSI-krossen påverkar kornformen och fillerhalten vid tillverkning av betongsand. Målet är att med avseende på dess påverkan bestämma vilken hastighet på VSI-krossen som bör användas samt undersöka vindsiktens kapacitet vid de olika fukthalterna. Instrument för mätning av fukthalt och bestämning av kornform har också studerats.

    Provtagningen utfördes i betongsandsanläggning vid Vikan Kross som ägs och drivs av Skanska Asfalt och Betong AB. Tester för att ta fram kornstorleksfördelningskurva, flisighetsindex och fukthalt genomfördes vid Skanskas laboratorium i Angered.

    Fukthaltens påverkan är tydligast vid lägre hastighet på VSI-krossen då fillerhalten mer än fördubblas när materialet går från torrt till fuktigt.

    Kornformen förbättras vid en högre hastighetsinställning på VSI-krossen, även fillerhalten i slutprodukten blir lägre. Bäst kornform uppnås vid torrt material.

    Den mängd filler som krossen genererar är också lägre vid den högre hastighetsinställningen, förutom vid mycket fuktigt material. Vindsiktens förmåga att reducera fillerhalten i materialet varierar kraftigt mellan fukthalterna.

    Studien av instrument resulterade i tre instrument som anses lämpliga för betongsandstillverkning. Ett portabelt och ett fastmonterat från Franz Ludwig GmbH för fuktmätning och ett instrument från Retsch Technology för bestämning av kornform.

  • 30.
    Halim, Adrianus
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Bolsöy, Tomas
    EOL Vent System AB.
    Klemo, Stina
    LKAB.
    The Nordic Ventilation System: An Overview2019Ingår i: Proceedings of the 17th North American Mine Ventilation Symposium / [ed] Ali Madiseh, Agus Sasmito, Ferri Hassani, Jozef Stachulak, Westmount, Quebec, 2019, s. 247-257Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes the ventilation system used in underground hard rock mines in Sweden and Finland, which is very different than the system used in other major mining countries such as Australia, Canada, South Africa, and USA. The system utilizes auxiliary fans with Variable Speed Drive (VSD) to distribute primary airflow to working levels instead of regulators that are commonly used in other countries. Descriptions about Ventilation on Demand (VOD) in this system and ventilation regulations in Sweden and Finland are presented in this paper. This paper also quantifies a comparison between the Nordic and the system used in other countries.

  • 31.
    Halim, Adrianus E.
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Brune, Jürgen
    Colorado School of Mines, Golden, USA.
    Do Refuge Chambers Represent a Good Strategy to Manage Emergencies in Underground Coal Mines?2019Ingår i: Mining, Metallurgy & Exploration, ISSN 2524-3462Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The 2006 Sago, Darby, and Aracoma mine disasters in the United States (US) forced the US government to implement the 2006MINER Act and additional regulations that require all US underground coal mines to install and maintain refuge chambers tomanage entrapment emergencies, in particular, fires and explosions. However, there is a debate on whether barricading in refugechambers is a good strategy to survive such emergencies. Australian coal mines are not required to use refuge chambers and,instead, have adopted a strategy that focuses on instructing and training miners to self-escape to the surface. This paper analyzesmerits and problems of using refuge chambers and self-escape to the surface to manage emergencies in fires or explosions in anunderground coal mine. The authors found that the use of refuge chambers may not be the best strategy during extensive fires orwhen multiple explosions happen. In these situations, mine rescuers are unlikely able to extract miners who are sheltered inchambers and conversely, self-escape may save more lives than sheltering. Chances for successful self-escape are furtherimproved by regular, externally assessed training such as Level 1 Emergency Exercises required in the Australian State of Queensland. These exercises put pressure on mine operators to ensure and maintain the effectiveness of their emergencymanagement system.

  • 32.
    Hugoson, Alexander
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Précenth, Henrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Kvalitetssäkrad Bultplansgenerering2016Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta examensarbete inom bergmekanik har utförts på uppdrag av Boliden under perioden april-maj 2016 i Bolidens underjordsgruva i Garpenberg.

    Bultriggarna i Garpenberg är utrustade med ett nytt system för att hjälpa operatören att positionera bergbultar enligt planerade bultmönster. Detta innebär att det önskade bultavståndet läggs manuellt in i maskinens dator och genom att referera till två tidigare installerade bultar genereras en plan för nästa bultkrans.

    Syftet med examensarbetet var att utföra en kvalitetskontroll gällande bultriggens navigeringssystem genom referensbultning. Genom att jämföra bultriggarnas datalogg mot mätningarna av verkligt utfall undersöktes om bultarna följde den angivna förstärkningsplanen.

    Arbetet har utförts genom att mäta in 8 bultkransar (totalt 104 installerade bultar) med  totalstation. Datan har sedan jämförs med bultriggarnas datalogg som automatisk genereras i mjukvaran vid installationen av varje bult. Datan har sedan analyserats med hjälp av datorprogrammen AutoCAD och Microsoft Excel för att beräkna avvikelsen mellan bultriggarnas datalogg och mätningarna av verkligt utfall (medelvärden, standardavvikelse och normalfördelning).

    Resultatet av mätningarna visar att 30,4 % av samtliga avvikelser från bultriggens datalogg ligger i intervallet 0-3 centimeter.

    Analysen visar en total standardavvikelse på 0,103 meter.

    Då analysen av avvikelser från bultriggens datalogg förutsätter att bultriggarnas sensorer är korrekta i sin precision har en kontrollmätning genomförts.

  • 33.
    Isaksson, Adam
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Evaluation of Scale-up Model for Flotation with Kristineberg Ore2018Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Syftet med det här examensarbetet var att utföra en detaljprovtagning av flotationskretsen i Bolidens anrikningsverk, massbalansera data och sedan utvärdera en modell för uppskalning av resultat från laboratorieflotationer. Modellen antar att hälften av utbytet till returgodset i ett satsvis laboratorieförsök skulle rapportera till det slutliga koncentratet om det återcirkulerades, såsom i ett anrikningsverk. Den har använts av Boliden Mineral AB sedan 1982 men utvärderades senast 1986. Kategoriskt kan den ses som en uppskalningsmodell av typen öppen krets med skalfaktorer.

    Projektet baserades på en komplex Ag-Au-Cu-Pb-Zn sulfidmalm från gruvan i Kristineberg. Laboratorieförsök utfördes för att ta fram koncentrat av CuPb, Cu, Pb och Zn, med pulpprover från driften som utgångsmaterial. Programmet HSC 9.3 användes för att massbalansera datan från provtagningen. Det bestämdes att modellen skulle anses som godtagbar ifall den kunde förutspå driftresultatet med samma noggrannhet som 1986. Ett simulerat försök av typen sluten krets (Agar & Kipkie, 1978) identifierades som den mest intressanta alternativmodellen och även den utvärderades.

    Resultaten visade att modellen än idag ger godtagbara förutsägelser med samma noggrannhet som 1986. Modellen var särskilt bra på att förutspå halt och utbyte av den huvudsakliga metallen till dess eget koncentrat. Den förutspådde exempelvis en 18 % högre halt och 11 % lägre utbyte av Cu till CuPb-koncentratet, samt 3 % lägre halt och 11 % lägre utbyte av Zn till Zn-koncentratet. Den alternativa modellen gav sämre förutsägelser med avseende på halter, men bättre med avseende på utbyten. Den var bättre på att förutspå beteendet hos låghaltiga föroreningar såsom As och Bi.

    Rekommendationen är att kombinera de två modellerna till en "blandkretsmodell". I den här undersökningen hade ett sådant alternativ förutspått en 18 % högre halt och 7 % lägre utbyte av Cu till CuPb-koncentratet, samt 3 % lägre halt och 1 % högre utbyte av Zn till Zn-koncentratet jämfört med driftresultatet. En sådan modell tycks ge bättre förutsägelser, men bör testas på fler prover och malmtyper. Den borde åtminstone kunna användas för att kontrollera trovärdigheten hos resultaten förutspådda av den nuvarande modellen.

  • 34.
    Jafari, Mohammad
    et al.
    School of Mining, College of Engineering, University of Tehran, Tehran, Iran.
    Chelgani, Saeed Chehreh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Shafaie, S.Z.
    School of Mining, College of Engineering, University of Tehran, Tehran, Iran.
    Abdollahi, H.
    School of Mining, College of Engineering, University of Tehran, Tehran , Iran.
    Hadavandi, E.
    Department of Industrial Engineering, Birjand University of Technology, Birjand, Iran.
    Study effects of conventional flotation reagents on bioleaching of zinc sulfide2019Ingår i: Journal of Industrial and Engineering Chemistry, ISSN 1226-086X, E-ISSN 1876-794X, Vol. 78, s. 364-371Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although flotation and bio-extraction of metals from its products are extensively investigated, there are few studied which evaluated the effects of reagents on bioleaching process. Both structure and concentration of flotation reagents are effective factors on microorganism activities. In this study, Kendall’s tau (τ) as a statistical method was used to statistically access the effect of typical sulfide flotation surfactants (collectors: potassium amyl-xanthate, potassium isobutyl-xanthate, sodium ethyl-xanthate, potassium isopropyl-xanthate, and Dithiophosphate), and frothers: pine oil and methyl isobutyl carbinol) on the bioleaching of Zn sulfides in a mixed culture (Leptospirillum ferrooxidans, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans). To consider both structure and concentration of these reagents, their molarities were used for the statistical evaluations. The Kendall assessments indicated that by increasing in the molarity of reagents, the pH value (the most effective factors of bioleaching) was increased (τ: 0.56) while the ORP value (τ: -0.54), Fe ratio (τ: -0.51) and numbers of oxidizing bacteria (τ: -0.38) in the solution were decreased. Therefore, as a result of these multi-interactions, by increasing the molarity of reagents, Zn recovery was decreased (τ: -0.45). These results potentially can be used for selection of flotation reagents when bioleaching would be the metallurgical metal extraction method.

  • 35.
    Johansson, Örjan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Pamidi, Taraka
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Khoshkhoo, Mohammad
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Sandström, Åke
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Sustainable and energy efficient leaching of tungsten(W) by ultrasound controlled cavitation2017Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The project aims to use ultrasound controlled cavitation to achieve a more energy efficient leaching process. Locally, collapsing cavitation bubbles cause an extremely high pressure, shock waves and high temperature, which provide an opportunity to perform the leaching process at a much lower temperature than in an autoclave (20 bar overpressure and 220 ° C). The results show that the method works, but that a higher static pressure and thus temperatures are necessary to achieve a leaching recovery rate corresponding to today's autoclave technology. Another process parameter of importance is flow control and the initiation of cavitation bubbles that occur through a geometrically optimized nozzle (orifice plate). Numerical and experimental adaptation of the developed reactor with respect to the leaching conditions (Sodium hydroxide and Scheelite concentrate), required more time than expected. Best test results show that an energy supplement with ultrasonic controlled cavitation of 104 kWh / kg increases the leaching recovery by 21%. The leaching reagent temperature 60° C was determined regarding available reference data and was thought to be close to optimum for intensive cavitation in atmospheric pressure. Optimum temperature relates to the leaching reagent, vaporization temperature, density, boiling point, surface tension, and viscosity. Generally, for leaching is that higher temperatures are required to increase the chemical reaction rate (requires overpressure). The modified reactor principle provides stable results and is possible to scale up. Higher cavitation intensity for shorter finishing time and higher recovery rate require advanced flow induction, multiple excitation frequencies adapted to the optimized reactor geometry, as well as optimal process pressure and temperature.

  • 36.
    Jorjani, E.
    et al.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Asadollahi Poorali, H.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Sam, A.
    Department of Mining Engineering, Shahid Bahonar University of Kerman, Iran.
    Chelgani, Saeed Chehreh
    Department of Mining Engineering, Research and Science Campus, Islamic Azad University, Iran.
    Mesroghli, Sh.
    Department of Mining Engineering, Research and Science Campus, Islamic Azad University, Iran.
    Shayestehfar, M. R.
    Department of Mining Engineering, Shahid Bahonar University of Kerman, Iran.
    Prediction of coal response to froth flotation based on coal analysis using regression and artificial neural network2009Ingår i: Minerals Engineering, ISSN 0892-6875, Vol. 22, nr 11, s. 970-976Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, the combustible value (i.e. 100-Ash) and combustible recovery of coal flotation concentrate were predicted by regression and artificial neural network based on proximate and group macerals analysis. The regression method shows that the relationships between (a) ln (ash), volatile matter and moisture (b) ln (ash), ln (liptinite), fusinite and vitrinite with combustible value can achieve the correlation coefficients (R2) of 0.8 and 0.79, respectively. In addition, the input sets of (c) ash, volatile matter and moisture (d) ash, liptinite and fusinite can predict the combustible recovery with the correlation coefficients of 0.84 and 0.63, respectively. Feed-forward artificial neural network with 6-8-12-11-2-1 arrangement for moisture, ash and volatile matter input set was capable to estimate both combustible value and combustible recovery with correlation of 0.95. It was shown that the proposed neural network model could accurately reproduce all the effects of proximate and group macerals analysis on coal flotation system.

  • 37.
    Jorjani, E.
    et al.
    Mining Engineering Department, Science and Research Branch Islamic Azad University, Iran.
    Bagherieh, A. H.
    Mining Engineering Department, Science and Research Branch Islamic Azad University, Iran.
    Chelgani, Saeed Chehreh
    Mining Engineering Department, Science and Research Branch Islamic Azad University, Iran.
    Rare earth elements leaching from Chadormalu apatite concentrate: Laboratory studies and regression predictions2011Ingår i: Korean Journal of Chemical Engineering, ISSN 0256-1115, Vol. 28, nr 2, s. 557-562Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The extraction of rare earth elements from apatite concentrate of Chadormalu plant of Iran was studied with the dissolution of ore in nitric acid. The parameters of acidity: 60%, solid to liquid ratio: 30%, leaching time: 30 minute, agitation rate: 200 rpm, temperature: 60 °C and particle size (d80): 50 microns were determined as the optimum operational conditions. The recoveries of lanthanum, cerium, neodymium and yttrium were achieved at 74, 59, 72 and 73%, respectively, in the optimized conditions. Multivariable regression was used to predict La, Ce, Nd, Y and total REEs (Y+Nd+Ce+La) leaching recoveries, using experimental data from laboratory studies. It was achieved quite satisfactory correlations of 0.93, 0.98, 0.99, 0.97 and 0.99 for the prediction of Y, Nd, Ce, La and total REEs recoveries, respectively. It was shown that the proposed equations accurately reproduce the effects of operational variables on the different REEs recoveries, and can be used to optimize the REEs leaching plant.

  • 38.
    Jorjani, E.
    et al.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University, Iran.
    Bagherieh, A. H.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University, Iran.
    Mesroghli, Sh.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University, Iran.
    Chelgani, Saeed Chehreh
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University, Iran.
    Prediction of yttrium, lanthanum, cerium, and neodymium leaching recovery from apatite concentrate using artificial neural networks2008Ingår i: Journal of University of Science and Technology Beijing: Mineral Metallurgy Materials (Eng Ed), ISSN 1005-8850, Vol. 15, nr 4, s. 367-374Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The assay and recovery of rare earth elements (REEs) in the leaching process is being determined using expensive analytical methods: inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectroscopy (ICP-MS). A neural network model to predict the effects of operational variables on the lanthanum, cerium, yttrium, and neodymium recovery in the leaching of apatite concentrate is presented in this article. The effects of leaching time (10 to 40 min), pulp densities (30% to 50%), acid concentrations (20% to 60%), and agitation rates (100 to 200 r/min), were investigated and optimized on the recovery of REEs in the laboratory at a leaching temperature of 60°C. The obtained data in the laboratory optimization process were used for training and testing the neural network. The feed-forward artificial neural network with a 4-5-5-1 arrangement was capable of estimating the leaching recovery of REEs. The neural network predicted values were in good agreement with the experimental results. The correlations of R=1 in training stages, and R=0.971, 0.952, 0.985, and 0.98 in testing stages were a result of Ce, Nd, La, and Y recovery prediction respectively, and these values were usually acceptable. It was shown that the proposed neural network model accurately reproduced all the effects of the operation variables, and could be used in the simulation of a leaching plant for REEs.

  • 39.
    Jorjani, E.
    et al.
    Department of Mining Engineering, Research and Science Campus, Islamic Azad University.
    Chelgani, Saeed Chehreh
    Department of Mining Engineering, Research and Science Campus, Islamic Azad University.
    Mesroghli, Sh.
    Department of Mining Engineering, Research and Science Campus, Islamic Azad University.
    Application of artificial neural networks to predict chemical desulfurization of Tabas coal2008Ingår i: Fuel, ISSN 00162361, Vol. 87, nr 12, s. 2727-2734Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a neural network model to predict the effects of operational parameters on the organic and inorganic sulfur removal from coal by sodium butoxide. The coal particle size, leaching temperature and time, sodium butoxide concentration and pre oxidation time by peroxyacetic acid (PAA) were used as inputs to the network. The outputs of the models were organic and inorganic sulfur reduction. Feed-forward artificial neural network with 5-7-10-1 arrangement, were capable to estimate organic and inorganic sulfur reduction, respectively. Simulated values obtained with neural network correspond closely to the experimental results. It was achieved quite satisfactory correlations of R2 = 1 and 0.96 in training and testing stages for pyritic sulfur and R2 = 1 and 0.97 in training and testing stages, respectively, for organic sulfur reduction prediction. The proposed neural network model accurately reproduces all the effects of operational variables and can be used in the simulation of Tabas coal desulfurization plant.

  • 40.
    Jorjani, E.
    et al.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Chelgani, Saeed Chehreh
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Mesroghli, Sh.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University.
    Prediction of microbial desulfurization of coal using artificial neural networks2007Ingår i: Minerals Engineering, ISSN 0892-6875, Vol. 20, nr 14, s. 1285-1292Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Artificial neural networks procedures were used to predict the organic and inorganic sulfur reduction from coal using mixed culture consisted ferrooxidans species extracted from coal washery tailings, for pyritic sulfur, and Rhodococcus species, extracted from oily soils, for the organic sulfur removal. The particle size, pulp density, initial pH, shaking rate, leaching time and temperature, in pyritic sulfur removal prediction, and pulp density, shaking rate, leaching time and temperature, in organic sulfur removal prediction, were used as inputs to the network. Feed-forward artificial neural networks with 4-8-4-1 and 3-5-6-1 arrangements, were capable to estimate organic and inorganic sulfur removal, respectively. The outputs of the models were percentage of organic and inorganic sulfur reduction. It was achieved quite satisfactory correlations of R2 = 1.00 and 0.98 in training and testing stages for pyritic sulfur removal prediction and R2 = 1.00 and 0.97 in training and testing stages, respectively, for organic sulfur removal prediction. The proposed neural network models accurately estimate the effects of operational variables in organic and inorganic desulphurization plants and can be used in order to optimize the process parameters without having to conduct the new experiments in laboratory.

  • 41.
    Jorjani, E.
    et al.
    Department of Mining Engineering, Research and Science Campus, Iran.
    Hower, J. C.
    Center for Applied Energy Research, University of Kentucky, USA.
    Chelgani, Saeed Chehreh
    Department of Mining Engineering, Research and Science Campus, Iran.
    Shirazi, M. A.
    Industrial Engineering Department, K.N. Toosi University of Technology, Iran.
    Mesroghli, Sh.
    Department of Mining Engineering, Research and Science Campus, Islamic Azad University, Iran.
    Studies of relationship between petrography and elemental analysis with grindability for Kentucky coals2008Ingår i: Fuel, ISSN 0016-2361, Vol. 87, nr 6, s. 707-713Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of macerals, ash, elemental analysis and moisture of wide range of Kentucky coal samples from calorific value of 23.65–34.68 MJ/kg (10,170–14,910 (BTU/lb)) on Hardgrove Grindability Index (HGI) have been investigated by multivariable regression method. Two sets of input: (a) macerals, ash and moisture (b) macerals, elemental analysis and moisture, were used for the estimation of HGI. The least square mathematical method shows that increase of the TiO2 and Al2O3 contents in coal can decrease HGI. The higher Fe2O3 content in coal can result in higher HGI. With the increase of micrinite and exinite contents in coal, the HGI has been decreased and higher vitrinite content in coal results in higher HGI. The multivariable studies have shown that input set of macerals, elemental analysis and moisture in non-linear condition can be achieved an acceptable correlation, R = 90.38%, versus R = 87.34% for the input set of macerals, ash and moisture. It is predicted that elemental analysis of coal can be a better representative of mineral matters for the prediction of HGI than ash.

  • 42. Jorjani, E.
    et al.
    Hower, J. C.
    Center for Applied Energy Research, University of Kentucky, USA.
    Mesroghli, Sh.
    Shirazi, M. A.
    Chelgani, Saeed Chehreh
    Bagherieh, A. H.
    Estimation of coal calorific value with petrography, ultimate analysis, moisture, Rmaxand ash using regression and artificial neural network methods2007Ingår i: 24th Annual International Pittsburgh Coal Conference 2007, 2007, Vol. 2, s. 1003-1015Konferensbidrag (Refereegranskat)
  • 43.
    Jorjani, E.
    et al.
    Department of Mining Engineering, Science and Research Branch, Islamic Azad University, Iran.
    Mesroghli, Sh.
    Department of Mining Engineering, Science and Research Branch, Islamic Azad University, Iran.
    Chelgani, Saeed Chehreh
    Department of Mining Engineering, Science and Research Branch, Islamic Azad University, Iran.
    Prediction of operational parameters effect on coal flotation using artificial neural network2008Ingår i: Journal of University of Science and Technology Beijing: Mineral Metallurgy Materials (Eng Ed), ISSN 1005-8850, Vol. 15, nr 5, s. 528-533Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Artificial neural network procedures were used to predict the combustible value (i.e. 100-Ash) and combustible recovery of coal flotation concentrate in different operational conditions. The pulp density, pH, rotation rate, coal particle size, dosage of collector, frother and conditioner were used as inputs to the network. Feed-forward artificial neural networks with 5-30-2-1 and 7-10-3-1 arrangements were capable to estimate the combustible value and combustible recovery of coal flotation concentrate respectively as the outputs. Quite satisfactory correlations of 1 and 0.91 in training and testing stages for combustible value and of 1 and 0.95 in training and testing stages for combustible recovery prediction were achieved. The proposed neural network models can be used to determine the most advantageous operational conditions for the expected concentrate assay and recovery in the coal flotation process.

  • 44.
    Jönsson, Simon
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Olsson, Albert
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Uppföljning av skuthantering i Aitik2017Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta examensarbete handlar om att följa upp skuthantering i Aitik och dess ekonomiska påverkan, Aitik är en dagbrottsgruva som ligger i Gällivares kommun. Skut är ett bergblock som är större än 1 m3 och är ett återkommande problem då de orsakar störningar i produktionsflödet. Totalt genomfördes tre fältstudier som inriktades på lastning, skutknackning och kross. Ett utav målen var att undersöka om det är lönsamt att låta Aitiks entreprenör knacka skut, detta genom att jämföra kostnaden som entreprenören fakturerar mot att hantera skuten som gråberg vilket medför en deponiförlust av kopparvärdet. Hantering av skut kan ske på två olika sätt, hantering vid upplag och hantering vid salva. Dessa två metoder jämförs för att se vilken som är mest lönsam. Ett annat mål var att undersökahur stor inverkan skut har i krossen då de orsakar stopp, och därefter jämföra dessa stopporsaker mot krossoperatörens inrapporterade stopporsak, vilket denne gör i Aitiks Sogetisystem.

    Studien åskådliggör att det inte är lönsamt att låta entreprenören hantera skut vid kopparhalten 0,06 %. För kopparhalter kring 0,1 % bör vidare undersökningar genomföras om det är lönsamt eller ej. Vid 0,2 % och över är det lönsamt med skuthantering från entreprenören. Skuthantering vid upplag är den mest lönsamma metoden så länge dieselpriset understiger 10 kr per liter. Skut har en stor negativ inverkan på produktionseffektiviteten i krossen. Totalt orsakades 86 minuter stopp i krossen på grund av skut under två skift. Detta motsvarar ca 400 000 kr i produktionsförlust, vid produktionseffektiviteten 4041 ton per timme vilket var den verkliga effektiviteten hos krossen under det ena skiftet. Olikheter påträffades vid jämförelse mellan dokumenterade stopporsaker och operatörernas stopporsaker i Sogeti.

    Vid uppföljande studier bör hänsyn tas till kostnader för truckslitage i beräkningar av skuthantering, då detta kan påverka resultatet. Fler fältstudier bör utföras för att få ett mer tillförlitlig resultat.

  • 45.
    Karldorff, Harri
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Dränerande bärlagermaterial: Produktion och egenskaper av bärlagermaterial i bergtäkterna Kjula och Eker2016Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I detta examensarbete framtogs två bärlagermaterial med hög dränerande förmåga från NCCs bergtäkt i Kjula samt standardprodukt 0/32 mm som användes som referens. De sökta egenskaperna som beaktades var hög permeabilitet, hög porositet, god bärighet och kostnadseffektiv produktion. Tester gjordes på materialens porositet, permeabilitet, vattenkvot och materialens kornstorleksfördelning analyserades.

    Materialet framtogs genom att avskilja 0/16 i ingående till kross och sedan sikta fram sortering 0/32 mm. Materialet analyserades i laboratorium där korndensitet och kornstorleksfördelning bestämdes. Vattenkvoten fastställdes genom torkning i ugn och permeabiliteten mättes med rörpermeameter.

    Resultaten visade att den viktigaste parametern för ett materials permeabilitet är andelen finmaterial (<0.063 mm) och genom förändring av ingående material till kross kan permeabiliteten och porositeten förändras i utgående materialet. Mätning av materialens egenskaper visade att permeabiliteten förbättrades till k = 4.4 * 10-3 m/s jämfört med referensmaterialet k = 1.8 * 10-4 m/s. Materialets porositet n ökade från n = 32.58 %, för referensmaterialet, till n = 37.96 %.

  • 46.
    Karlkvist, Tommy
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Selectivity in Calcium mineral flotation - An analysis of novel an existing approaches2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 47.
    Karlkvist, Tommy
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Pålsson, Bertil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Synergism among collectors used for flotation of apatite and REE mineralsManuskript (preprint) (Övrigt vetenskapligt)
  • 48.
    Khorami, M. T.
    et al.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University, Iran.
    Chelgani, Saeed Chehreh
    Surface Science Western, Research Park, University of Western Ontario, Candada.
    Hower, J. C.
    Center for Applied Energy Research, University of Kentucky, USA.
    Jorjani, E.
    Department of Mining Engineering, Science and Research Branch,Islamic Azad University, Iran.
    Studies of relationships between Free Swelling Index (FSI) and coal quality by regression and Adaptive Neuro Fuzzy Inference System2011Ingår i: International Journal of Coal Geology, ISSN 0166-5162, Vol. 85, nr 1, s. 65-71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The results of proximate, ultimate, and petrographic analysis for a wide range of Kentucky coal samples were used to predict Free Swelling Index (FSI) using multivariable regression and Adaptive Neuro Fuzzy Inference System (ANFIS). Three different input sets: (a) moisture, ash, and volatile matter; (b) carbon, hydrogen, nitrogen, oxygen, sulfur, and mineral matter; and (c) group-maceral analysis, mineral matter, moisture, sulfur, and Rmax were applied for both methods. Non-linear regression achieved the correlation coefficients (R2) of 0.38, 0.49, and 0.70 for input sets (a), (b), and (c), respectively. By using the same input sets, ANFIS predicted FSI with higher R2 of 0.46, 0.82 and 0.95, respectively. Results show that input set (c) is the best predictor of FSI in both prediction methods, and ANFIS significantly can be used to predict FSI when regression results do not have appropriate accuracy.

  • 49.
    Koch, Pierre-Henri
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Computational methods and strategies for geometallurgy2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    At the interface of geology and mineral processing, geometallurgy is a powerful tool for enhancingresource efficiency. A spatial model that represents the ore body in terms ofmineralogyand physical properties is combined with a process model that describes the concentrationprocess. The performance of a given ore in the process is computed in terms of gradeand recovery of the mineral of interest in the concentrate, but also the presence of potentialpenalty elements and energy costs. The inclusion of ore performance indicators in a blockmodel yields a geometallurgical model that considers the variations in an ore body.Progress has been made in recent years to list and study different processing options interms of data requirements and implementation costs. While providing useful data, littleadvance was made to guide decision-making and to handle uncertainty. The objective has,therefore, been to develop, choose and validate computational methods that suggest optimaldecisions in the scope of geometallurgical strategies for an iron ore and a porphyry copperdeposit.The selected approach is based on an analysis of structure and regularity fromthe ore blockdown to the mineral grains. By selecting the appropriate mathematical tool for each scale,the dimension of the data is reduced and the different scales are then taken into account inmaking decisions. Methods introduced for dimension reduction include machine learningmodels, statistical models and spectral descriptors. The decision models rely on stochasticmulti-armed bandits which are a form of reinforcement learning. The presentation of thedifferent models proceeds by zooming in from coarse scale to fine scale then taking a stepback and analyze the implications. Data that was collected during sampling campaigns andindustrial plant surveys is used to design and verify the proposedmodels.iWith regard to the dimension reduction problem, results showed the method’s ability toclassify mineral textures and identify mineral phases with more than 90 percent accuracy onthe selected data sets of optical images and incorporate different physical properties into ageometallurgical ore type classification. Decision results showed that strategies in the case ofa feed grade control or when different ore types were identified, resulted in a twofold increaseof a reward function which is either Boolean (the product fulfills quality requirements ornot), or continuous (an economic objective). The cumulative value of the reward functionmeasured the optimality of a processing strategy. Quantitative methods were introduced toevaluate ore classification as well as geometallurgical strategies.The achieved results suggest the introduction of these computationalmethods in the practiceof geometallurgy. The increased knowledge of different ore type performances and appropriatemodels lead to optimal decisions for improved resource efficiency along the ore valuechain. This is achieved by bothmaximizing profit and decreasing environmental impact, forexample by choosing processing routes that minimize energy consumption.

  • 50.
    Koch, Pierre-Henri
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Particle generation for geometallurgical process modeling2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    A geometallurgical model is the combination of a spatial model representing an ore deposit and a process model representing the comminution and concentration steps in beneficiation. The process model itself usually consists of several unit models. Each of these unit models operates at a given level of detail in material characterization - from bulk chemical elements, elements by size, bulk minerals and minerals by size to the liberation level that introduces particles as the basic entity for simulation (Paper 1).

    In current state-of-the-art process simulation, few unit models are defined at the particle level because these models are complex to design at a more fundamental level of detail, liberation data is hard to measure accurately and large computational power is required to process the many particles in a flow sheet. Computational cost is a consequence of the intrinsic complexity of the unit models. Mineral liberation data depends on the quality of the sampling and the polishing, the settings and stability of the instrument and the processing of the data.

    This study introduces new tools to simulate a population of mineral particles based on intrinsic characteristics of the feed ore. Features are extracted at the meso-textural level (drill cores) (Paper 2), put in relation to their micro-textures before breakage and after breakage (Paper 3). The result is a population of mineral particles stored in a file format compatible to import into process simulation software. The results show that the approach is relevant and can be generalized towards new characterization methods.

    The theory of image representation, analysis and ore texture simulation is briefly introduced and linked to 1-point, 2-point, and multiple-point methods from spatial statistics. A breakage mechanism is presented as a cellular automaton. Experimental data and examples are taken from a copper-gold deposit with a chalcopyrite flotation circuit, an iron ore deposit with a magnetic separation process.

    This study is covering a part of a larger research program, PREP (Primary resource efficiency by enhanced prediction).

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