Change search
Refine search result
12 1 - 50 of 91
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abrahamsson, Filip
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Leaching of Pyrrhotite from Nickel Concentrate2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Non-oxidative acid leaching of pyrrhotite from Kevitsa’s Ni-concentrate and methods to recover by-products, have been investigated. Selective dissolution of pyrrhotite (Fe1-xS, 0<x<0.25) can enrich the content of the valuable metals, such as Ni and Co, in the final concentrate and will reduce the amount of Fe and S sent to the smelters. The pyrometallurgical smelting of leached concentrate will thus give less formation of smelter by-products in form of slag and SO2. The leaching was studied through an experimental design plan with parameter settings of  38.8% to 57.8% H2SO4 and temperatures from 60 to 100°C. The best results were obtained in experiments carried out at the lower experimental range. Leaching at 60°C with an initial acid concentration of 38.8% H2SO4 was found sufficient to selectively dissolve most of the pyrrhotite; leaving an enriched solid residue. A QEMSCAN analysis of the solid residue confirmed that most of the pyrrhotite had been dissolved and showed that pentlandite was still the main Ni-mineral. Chemical assays showed that more than 95% of the Ni, Co, and Cu remained in the final residue.

       The utilized leaching process generates by-products, in the form of large quantities of Fe2+ in solution and gaseous H2S. To recover Fe2+, crystallization of iron(ii) sulfate (FeSO4∙nH2O) from leach solution through cooling have been studied. The crystallized crystals were further dehydrated into the monohydrate (FeSO4∙H2O) through a strong sulfuric acid treatment (80%H2SO4). XRD analysis confirmed that FeSO4∙H2O was the main phase in the final crystals, and a chemical analysis showed a Fe content of about 30%, 1.5% Mg, 0.4% Ca, and 0.2% Ni.

       The possibility to leach the concentrate by circulating the acidic solution from the crystallization stage has been tested. The recirculation of the solution showed no negative effects, as the recoveries of elements and chemical assays of the final solid residue were found to be similar to the obtained assay when the concentrate was leached in a fresh solution.

  • 2.
    Al-Douri, Yamur K.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Hamodi, Hussan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Data imputing using generic algorithms (GA)2017In: 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, p. 205-208Conference paper (Refereed)
  • 3.
    Ataide Salvador, Dandara
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Geometallurgical Variability Study of Spodumene Pegmatite Ores, Central Ostrobothnia - Finland2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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 University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Geometallurgical approach to understand how the variability in mineralogy at Zinkgruvan orebodies affects the need for copper activation in the bulk rougher-scavenger flotation2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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 University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Mobil bergkrossning: Energibehov och emissioner2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    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 University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Utredning om dimension av kamjärnsbultar i Garpenbergsgruvan2018Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
  • 7.
    Bertilsson, Olle
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Study of leaching behavior of tin in Zinc-clinker and Mixed Oxide2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    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 University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Flödeskalibrering: Analys av kalibreringsprocesser2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In December 2015 the Paris Agreement was signed in order to create a better global climate. According to the agreement, all countries 'emissions shall be reported to the UN. To be able to do this current emission levels must be known, which means measurement and calculation of emissions are necessary.

     

    The state-owned mining company Luossavaara Kiirunavaara AB (LKAB) operates iron ore mines in Northen Sweden. The iron ore products produced at the KK4 coal mill in Kiruna, consists of some additives that form carbon dioxide when burned. The amount of additives burned is measured using two flowmeters. To ensure that these meters have approved accuracy, annual calibrations are performed where measured volume is compared to a reference volume. In order to ensure that LKAB's calibration method works, another type of calibration was performed by an external company. The results between the two calibration methods differ significantly, which led to this report.

     

    The purpose of this work is to develop improvement proposals for LKAB's calibration method and to present suggestions on how LKAB can create better conditions for the other so called transit time calibration method. By analyzing each method and performing measurements, tests and calculations, weaknesses are noted. Tests show that a weakness of LKAB's calibration is that the level measurement method used is person-dependent. Level measurement with laser range gauge is tested with good results, why this type of measurement is recommended in the future. The main weakness with transit time method is primarily that it is sensitive to variation of the inner diameter of the pipe. In order for this method to provide reliable results, rebuilding of pipes and carefully measured internal diameter are required. Accurate flow measurement means that current carbon dioxide emissions can be calculated, which enables continued work towards set environmental goals. Flowmeters also have a significant role in product quality in KK4, which means that this report can contribute to higher quality and economic profitability.

  • 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 systems2011In: Energy Exploration and Exploitation, ISSN 01445987, Vol. 29, no 4, p. 479-494Article in journal (Refereed)
    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 University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. 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 ANFIS2011In: International Journal of Coal Preparation and Utilization, ISSN 1939-2699, Vol. 31, no 1, p. 9-19Article in journal (Refereed)
    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.

  • 11.
    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-EDX2012In: Minerals Engineering, ISSN 0892-6875, Vol. 30, p. 62-66Article in journal (Refereed)
    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.

  • 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 surface chemistry effects on collector adsorption by TOF-SIMS2012In: Minerals Engineering, ISSN 0892-6875, Vol. 39, p. 71-76Article in journal (Refereed)
    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.

  • 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 the relationship between the compositional zoning of high iron content pyrochlore and adsorption of cationic collector2013In: Minerals Engineering, ISSN 0892-6875, Vol. 46-47, p. 34-37Article in journal (Refereed)
    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.

  • 14.
    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 network2011In: Fuel Processing Technology, ISSN 0378-3820, Vol. 92, no 3, p. 349-355Article in journal (Refereed)
    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.

  • 15.
    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 models2008In: Fuel Processing Technology, ISSN 0378-3820, Vol. 89, no 1, p. 13-20Article in journal (Refereed)
    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.

  • 16.
    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 predictor2011In: Fuel, ISSN 0016-2361, Vol. 90, no 11, p. 3156-3163Article in journal (Refereed)
    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.

  • 17.
    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 methods2013In: Fuel Processing Technology, ISSN 0378-3820, Vol. 110, p. 79-85Article in journal (Refereed)
    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.

  • 18.
    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 network2010In: International Journal of Coal Geology, ISSN 0166-5162, Vol. 83, no 1, p. 31-34Article in journal (Refereed)
    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.

  • 19.
    Danielsson, Markus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Ghosh, Rajib
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Navarro Miguel, J.
    Universidad Politechnica de Madrid.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Schunnesson, Håkan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Utilizing production data to predict operational disturbances in sublevel caving2017In: 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, p. 139-144Conference paper (Refereed)
  • 20.
    de Groot, Laura
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Studie av omskjutningar i tunneldrivningsprojekt2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    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.

  • 21.
    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 networks2010In: Mining Science and Technology, ISSN 1674-5264, Vol. 20, no 1, p. 41-46Article in journal (Refereed)
    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.

  • 22.
    Ghodrati, Behzad
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Kumar, UdayLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.Schunnesson, HåkanLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Proceeding of the 26th International Symposium on Mine Planning and Equipment Selection: MPES 20172017Conference proceedings (editor) (Refereed)
  • 23.
    Ghosh, Rajib
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Assessment of rock mass quality and its effects on charge ability using drill monitoring technique2017Doctoral thesis, comprehensive summary (Other academic)
    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.

  • 24.
    Ghosh, Rajib
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Schunnesson, Håkan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Gustafson, Anna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Monitoring of Drill System Behavior for Water-Powered in-the-hole (ITH) drilling2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 7, article id 121Article in journal (Refereed)
    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

  • 25.
    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 design2013In: International Journal of Mining Science and Technology, ISSN 2095-2686, Vol. 23, no 2, p. 261-265Article in journal (Refereed)
    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.

  • 26.
    Guiral Vega, Juan Sebastian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    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.2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • 27.
    Haglund, Elin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Fukthaltens påverkan på maskintillverkad betongsand vid Vikan Kross2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis examines how the moisture content of the input material as well as the speed setting on the VSI-crusher affect grain shape and filler content in manufactured concrete sand. The aim of this thesis is to determine the most effective speed setting on the VSI-crusher and additionally to examine the capacity of the windsift at different moisture levels. Some suitable instruments for measuring humidity and determining grain shapes have also been studied.

    Sampling was conducted in the concrete sand plant at Vikan Kross owned and operated by Skanska Asfalt and Betong AB. Tests to produce grain size distribution curve, fleakiness index and moisture content were performed at Skanska´s laboratory in Angered.

    The impact of moisture is more evident at a lower speed setting on the VSI-crusher, the filler content is more than doubled when the material goes from dry to humid.

    The grain shape is improved at a higher speed setting on the VSI-crusher, also the filler content in the manufactured concrete sand is lower. Best grain shape is achieved in dry material.

    The amount of filler that the crusher generates is also lower at the higher speed setting, except for very wet material. The windsifts ability to reduce filler content in the material varies greatly between moisture levels.

    The study of instruments resulted in three instruments considered suitable for concrete sand manufacturing, one portable and one permanently installed from Franz Ludwig GmbH for moisture measurement and one instrument from Retsch Technology for determination of grain shape.

  • 28.
    Halim, Adrianus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Bolsöy, Tomas
    EOL Vent System AB.
    Klemo, Stina
    LKAB.
    The Nordic Ventilation System - An Overview2019In: Proceedings of the 17th North American Mine Ventilation Symposium / [ed] Ali Madiseh, Agus Sasmito, Ferri Hassani, Jozef Stachulak, Westmount, Quebec, 2019, p. 247-257Conference paper (Refereed)
    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.

  • 29.
    Hugoson, Alexander
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Précenth, Henrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Kvalitetssäkrad Bultplansgenerering2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis in rock mechanics was carried out on behalf of Boliden during the period of April to May 2016 at Boliden underground mine in Garpenberg.

    The bolting rigs in Garpenberg are equipped with a new system to assist the operator to position the rock bolts according to the planned bolting pattern. This means that the planned bolt spacing is manually inserted in the bolt positioning software and by referring to two previously installed bolts the planned location of the next bolting fan is generated and shown in the software.

    The aim of the thesis was to perform a quality control regarding the bolting rigs navigation system by reference bolting. Through comparing the bolting rigs data log with the measurements of the actual outcome it was determined if the location of the bolts were positioned according to the specified rock support plan.

    The work was performed by measuring the location of eight bolting fans (a total of 104 installed bolts) with a total station. The data was then compared with a data log that is automatically generated in the software at the installation of each bolt. The data has mainly been analysed using computer software such as AutoCAD and Microsoft Excel in order to calculate deviation of the bolting rigs data log and the measurements of actual outcome (mean values, standard deviation and normal distribution).

    The result of the measurements shows that 30.4% of all rock bolts are in the range of 0-3 centimetres from their planned locations.

    The analysis shows a total standard deviation of 0.103 metres.

    The analysis of deviations requires that the sensors on the joints of the bolting rigs are calibrated for the bolt positioning software and therefore control measurements were carried out.

  • 30.
    Isaksson, Adam
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Evaluation of Scale-up Model for Flotation with Kristineberg Ore2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The objectives of this project were to survey the flotation circuit of the Boliden concentrator, mass balance collected data and evaluate a scale-up model for laboratory flotation results. The model assumes that half of the recovery to cleaner middlings in a standard laboratory test would report to the final concentrate if it were done in closed circuit, as is the case in a full-scale plant. It has been used by Boliden Mineral AB since 1982 but its accuracy had not been studied since 1986. The model can be categorised as of open circuit type with scale-up factors.

    The project was based on a complex Ag-Au-Cu-Pb-Zn sulphide ore from the Kristineberg mine. Laboratory tests were done to produce concentrates of CuPb, Cu, Pb and Zn with pulp samples from the concentrator as feed material. The software HSC 9.3 was used to mass balance data from the plant survey. It was decided that the model would be deemed usable if it was able to predict the plant results with the same accuracy as in the survey of 1986. A simulated locked cycle test with split factors (Agar & Kipkie, 1978) was identified as an alternative scale-up model.

    The results showed that the model was able to predict the plant results with the same accuracy as in 1986. It was especially good at predicting grade and recovery of the main element in a concentrate. For example, it predicted an 18 % higher grade and 11 % lower recovery of Cu to the CuPb concentrate, while a 3 % lower grade and 11 % lower recovery of Zn was predicted to the Zn concentrate. The locked cycle model gave much worse predictions on grades, but more accurate recoveries. It was also better at predicting the behaviour of minor impurity elements such as As and Bi.

    A recommendation is to combine the two alternatives in a type of "mixed cycle" model. In this study, it would have predicted an 18 % higher grade and 7 % lower recovery of Cu to the CuPb concentrate, as well as a 3 % lower grade and 1 % higher recovery of Zn to the Zn concentrate compared with plant results. Such a model seems to give better figures, but should be put to the test on more samples and ores to confirm this belief. It could at the very least be used to check the reliability of results predicted by the current scale-up model.

  • 31.
    Johansson, Örjan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Pamidi, Taraka
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Khoshkhoo, Mohammad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sandström, Åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sustainable and energy efficient leaching of tungsten(W) by ultrasound controlled cavitation2017Report (Other academic)
    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.

  • 32.
    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 network2009In: Minerals Engineering, ISSN 0892-6875, Vol. 22, no 11, p. 970-976Article in journal (Refereed)
    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.

  • 33.
    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 predictions2011In: Korean Journal of Chemical Engineering, ISSN 0256-1115, Vol. 28, no 2, p. 557-562Article in journal (Refereed)
    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.

  • 34.
    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 networks2008In: Journal of University of Science and Technology Beijing: Mineral Metallurgy Materials (Eng Ed), ISSN 1005-8850, Vol. 15, no 4, p. 367-374Article in journal (Refereed)
    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.

  • 35.
    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 coal2008In: Fuel, ISSN 00162361, Vol. 87, no 12, p. 2727-2734Article in journal (Refereed)
    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.

  • 36.
    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 networks2007In: Minerals Engineering, ISSN 0892-6875, Vol. 20, no 14, p. 1285-1292Article in journal (Refereed)
    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.

  • 37.
    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 coals2008In: Fuel, ISSN 0016-2361, Vol. 87, no 6, p. 707-713Article in journal (Refereed)
    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.

  • 38. 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 methods2007In: 24th Annual International Pittsburgh Coal Conference 2007, 2007, Vol. 2, p. 1003-1015Conference paper (Refereed)
  • 39.
    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 network2008In: Journal of University of Science and Technology Beijing: Mineral Metallurgy Materials (Eng Ed), ISSN 1005-8850, Vol. 15, no 5, p. 528-533Article in journal (Refereed)
    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.

  • 40.
    Jönsson, Simon
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Olsson, Albert
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Uppföljning av skuthantering i Aitik2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is about following up the handing of boulders and its economic impact. Aitik is an open-pit mine located near Gällivare in Norrbotten. According to Aitik, a boulder is a rough stone that is larger than 1 m3, and they are a recurrent problem because boulders cause a disturbance in the production flow. A total of three field studies were done which focused on loading, boulder breaking and crushing. The goal was to investigate if it was going to be profitable to let Aitik´s entrepreneur handle boulders using a hydraulic breaker, thus comparing the invoice from Aitik´s entrepreneur compared to handling the boulders as waste rock, which entails a landfill loss of the copper value. The handling of boulders can occur in two different ways, handling at stockpile or handling at burst. These two methods are compared with each other to see which one is the most profitable. Beyond this it was also examined on how much of an impact boulders have in the crushing section when they cause a stop, and thereafter compare these stops against the reported stoppage from the operators which is done in Aitiks Sogetisystem.

    The study illustrates that it is not profitable to let Aitik´s entrepreneur handle boulders at the copper content 0,06 %. Copper concentrations around 0,1 % should be further analyzed whether it is profitable or not. At 0,2 % and above it is profitable to let Aitik´s entrepreneur handle the boulders. Handling boulders at stockpile is the most profitable method as long as the fuel cost is below 10 SEK per liters. Boulders have a large negative impact on the production efficiency in the crushing section. In two shifts there were a total of 86 minutes stop in the crusher caused by boulders, this corresponds to about 400 000 SEK in production loss at a production efficiency of 4041 tons per hour, which was the actual efficiency during one of the shifts. Differences occurred among the documented stop causes and the stop causes made by the operators in Sogeti.

    For further studies, a regard should be made occurring costs of truck wear due to boulder handling as this may affect the results. Also perform more field studies in order to get a more reliable result.

  • 41.
    Karldorff, Harri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Dränerande bärlagermaterial: Produktion och egenskaper av bärlagermaterial i bergtäkterna Kjula och Eker2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    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 %.

  • 42.
    Karlkvist, Tommy
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Selectivity in Calcium mineral flotation - An analysis of novel an existing approaches2017Doctoral thesis, comprehensive summary (Other academic)
  • 43.
    Karlkvist, Tommy
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Synergism among collectors used for flotation of apatite and REE mineralsManuscript (preprint) (Other academic)
  • 44.
    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 System2011In: International Journal of Coal Geology, ISSN 0166-5162, Vol. 85, no 1, p. 65-71Article in journal (Refereed)
    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.

  • 45.
    Koch, Pierre-Henri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    A numerical study of the effects of microwavepre-treatment on value liberation from a zinc ore2018In: Proceedings of the IMPC 2018, 2018Conference paper (Refereed)
  • 46.
    Koch, Pierre-Henri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Computational methods and strategies for geometallurgy2019Doctoral thesis, comprehensive summary (Other academic)
    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.

  • 47.
    Koch, Pierre-Henri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Particle generation for geometallurgical process modeling2017Licentiate thesis, comprehensive summary (Other academic)
    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).

  • 48.
    Koch, Pierre-Henri
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rosenkranz, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Texture-based liberation models for comminution2017In: Konferens i Mineralteknik 2017: Luleå 7-8 februari 2017, Luleå, 2017, p. 83-96Conference paper (Other academic)
    Abstract [en]

    The relation between breakage mechanisms and liberation is critical in mineral processing. Recent studies underline the importance of texture in liberation. This study reviews relevant liberation models and proposes a new method for generating particles using image processing algorithms. One new texture simulation method and its relevance for liberation simulation is also introduced.

  • 49.
    Larsson, Pontus
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Optimization of the steel-fiber dosage in shotcrete used in the Kankberg mine2018Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    The Swedish metal company Boliden has since the early 20th century been mining deposits in the mining field commonly referred to as the Skelleftefield in northern Sweden. The youngest of the active mines is the Kankberg mine which is an underground mine whose reserve contains gold and tellurium. The reserve of the mine is split-up into multiple smaller orebodies that are all being mined continuously using a cut- and fill mining method in combination with pillars utilized to ensure stability in certain stopes.

     

    The Kankberg mine is unique in the sense that it is situated in very hard rock. That in combination with medium stresses as results of the mining depth results in favorable conditions in terms of needed rock support. Boliden therefore wants to reduce the amount of support material used, without compromising the stability of the support system and the security of the underground personnel.

     

    The goal of this thesis is to present a recommend steel fiber dosage to be used in the shotcrete. The recommendation is based upon:

     

    • Test results of round determinate panel (RPD) tests according to the ASTM C1550-12a (American Society for Testing) standard.
    • Reviews of earlier shotcrete tests conducted by Boliden.
    • A literature study focused on fiber dosages in other underground projects.
    • Stress analyses using numerical methods.
    • Rock inspections and rock classifications.
    • International guidelines regarding fiber dosages used in shotcrete.

     

    The results presented within this thesis suggest that the fiber dosage in the shotcrete recipe can be lowered, in favor of cost optimization. The optimal dosage, when factoring in the issues related to the continuous mining, the energy absorption capacity of the shotcrete and general recommendations from studied literature was determined being a dosage of 22.6 kg/m3. The thesis further suggests that large scale tests should be conducted on a full scale before the lowered dosage is adopted in practice.

  • 50.
    Lestander, Malin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Multi Role Face Drill: Evaluation of the 2 Boom Face Drill in Australia Based on Swedish Design Criteria2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The 2 boom development face drill rig is originally designed for drilling blast holes. Currently in Australian mines the rig is utilised as a multi role face drill for drilling blast holes and rock reinforcement such as scaling, semi-mechanised bolting and meshing. The aim of the study is to understand if the machines produced today are what Australia demands.

    It is important that the development is carried out in the most efficient way possible. There are a number of drilling methods and multiple factors to consider when choosing which method to use. One way of increasing the advance rate is to extend the rounds. A computerised control system allows longer rounds while maintaining the same advance per round. Longer rounds means however longer feeds on the face drill which in turn creates problems in other operations at the face.

    Simulations of multi role equipment have shown that they can both increase and decrease the developed metres. The outcome of exchanging two or more dedicated equipment into one multi role equipment is a higher general availability but with limitations of having access to only one function at the time.

    In a 2-, 3- or 4-heading scenario and if having set firing times in the mine and same length of the rounds and cycle times, then 2 multi role face drills can perform the same amount of work as 3 dedicated rigs. This is due to the time it takes for bolting and the fact that the total work cycle is longer than a shift.

    Bolting with mesh and resin bolts is the longest cycle time, making it the bottleneck, and therefore focus should be to improve this. Utilising the face drill for scaling and bolting shows a significant increase of the unplanned breakdowns.

    In regards to the new face drill that was recently released on the Australian market a lot of the factors causing unplanned breakdown have been improved. However, the hydraulic hoses are still exposed on the feed and will most likely continue to break if the rig continues being utilised as a multi role face drill.

    In order to combine a computerised control system with a multi role face drill and at the same time maintain good availability, hoses, cables and sensors need to be protected or somehow eliminated from the boom and feed.

12 1 - 50 of 91
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf