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  • 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.

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  • 2.
    Al-Chalabi, Hussan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Al-Douri, Yamur K.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lundberg, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Time Series Forecasting using ARIMA Model: A Case Study of Mining Face Drilling Rig2018In: ADVCOMP 2018: The Twelfth International Conference on Advanced Engineering Computing and Applications in Sciences / [ed] Claus-Peter Rückemann; Ahmad Rafi Qawasmeh, International Academy, Research and Industry Association (IARIA), 2018, p. 1-3Conference paper (Refereed)
    Abstract [en]

    This study implements an Autoregressive Integrated Moving Average (ARIMA) model to forecast total cost of a face drilling rig used in the Swedish mining industry. The ARIMA model shows different forecasting abilities using different values of ARIMA parameters (p, d, q). However, better estimation for the ARIMA parameters is required for accurate forecasting. Artificial intelligence, such as multi objective genetic algorithm based on the ARIMA model, could provide other possibilities for estimating the parameters. Time series forecasting is widely used for production control, production planning, optimizing industrial processes and economic planning. Therefore, the forecasted total cost data of the face drilling rig can be used for life cycle cost analysis to estimate the optimal replacement time of this rig.

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  • 3.
    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)
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  • 4.
    Almgren, G.
    Luleå University of Technology.
    Lulea Colleges And Mining Engineering1977In: JERNKONTORETS ANNALER, Vol. 161, no 3, p. 58-60Article in journal (Refereed)
  • 5.
    Altuntov, Firdevs Kübra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Skawina, Bartlomiej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Greberg, Jenny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Engberg, H
    General Manager Mining Technology, Loussavaara-Kiirunavaara Aktiebolag (LKAB), Kiruna Norrbotten 981 86, Sweden.
    Niia, I
    Mine Planner, Loussavaara-Kiirunavaara Aktiebolag (LKAB), Kiruna Norrbotten 981 86, Sweden.
    An initial review of conceptual alternative layouts for production areas in Kiirunavaara mine2023In: Underground Operators Conference 2023: Conference Proceedings, The Australasian Institute of Mining and Metallurgy , 2023, p. 200-208Conference paper (Refereed)
  • 6.
    Amini, Hasel
    et al.
    Faculty of Mining, Petroleum and Geophysics, University of Shahrood, Shahrood, Iran.
    Torabi, Seyed Rahman
    Faculty of Mining, Petroleum and Geophysics, University of Shahrood, Shahrood, Iran.
    Hoseinie, Seyed Hadi
    Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran.
    Ghodrati, Behzad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    RAM analysis of earth pressure balance tunnel boring machines: A case study2015In: International Journal of Mining and Geo-Engineering, ISSN 2345-6930, Vol. 49, no 2, p. 173-185Article in journal (Refereed)
    Abstract [en]

    Earth pressure balance tunnel boring machines (EPB-TBMs) are favorably applied in urban tunneling projects. Despite their numerous advantages, considerable delays and high maintenance cost are the main disadvantages these machines suffer from. Reliability, availability, and maintainability (RAM) analysis is a practical technique that uses failure and repair dataset obtained over a reasonable time for dealing with proper machine operation, maintenance scheduling, cost control, and improving the availability and performance of such machines. In the present study, a database of failures and repairs of an EBP-TBM was collected in line 1 of Tabriz subway project over a 26-month interval of machine operation. In order to model the reliability of the TBM, this machine was divided into five distinct subsystems including mechanical, electrical, hydraulic, pneumatic, and water systems in a series configuration. According to trend and serial correlation tests, the renewal processes were applied, for analysis of all subsystems. After calculating the reliability and maintainability functions for all subsystems, it was revealed that the mechanical subsystem with the highest failure frequency has the lowest reliability and maintainability. Similarly, estimating the availability of all subsystems indicated that the mechanical subsystem has a relatively low availability level of 52.6%, while other subsystems have acceptable availability level of 97%. Finally, the overall availability of studied machine was calculated as 48.3%.

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  • 7.
    Andrén, Anna
    et al.
    The Swedish Transport Administration, Borlänge, Sweden.
    Dahlström, Lars-Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Degradation of the Reinforcing Effect of Shotcrete: Freeze-Thaw Tests on Shotcrete-Rock Panels2020In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 25, no 1, p. 1-30Article in journal (Refereed)
    Abstract [en]

    In rock tunnels in regions with colder climates, the load-bearing structure, including the rock and the reinforcing elements, is exposed to repeated destructive freezing and thawing cycles during the winter. If water accumulates in cracks or in the interface between rock and shotcrete, frost shattering may occur. If there is adequate adhesion between the rock and shotcrete, degradation of the shotcrete as a reinforcement element due to frost shattering should not present a problem. However, if adhesion is poor, a small void will form between the rock and the shotcrete where water can accumulate. If the water in these voids is subjected to freeze-thaw cycles, ice will develop, thus exerting pressure on the interface and causing the shotcrete to crack and degrade. In tunnel sections with complex water conditions, for example, relatively water-bearing open joints and weak zones, the adhesion of the shotcrete and its stability and reinforcing effect may be strongly affected when exposed to freezing temperatures. This article describes a laboratory study that comprised freeze-thaw tests on shotcreterock panels with the objective of studying how water migration affects the growth of ice and the ice pressure in the shotcrete-rock interface to better understand the degradation of the reinforcing effect of shotcrete

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  • 8.
    Andrén, Anna
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. The Swedish Transport Administration, Borlänge, Sweden.
    Dahlström, Lars-Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Evaluation of a laboratory model test using field measurements of frost penetration in railway tunnels2022In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 204, article id 103660Article in journal (Refereed)
    Abstract [en]

    Despite extensive grouting efforts to prevent water from leaking into tunnels, water seepages remain. When exposed to freezing temperatures, ice formations occur. During the winter, the Swedish Transport Administration's railway tunnels are affected by major problems caused by ice, such as icicles from roof and walls, ice loads on installations, ice-covered tracks and roads, etc. To ensure safety and prevent traffic disruptions, many tunnels require extensive maintenance. Improved knowledge about frost penetration in tunnels is required to reduce maintenance of the tunnels. Frost insulated drain mats are often used at leakage spots to prevent ice formation along the tunnels. To find out which parts of a tunnel are exposed to freezing temperatures, the University of Gävle and the Royal Institute of Technology in Stockholm conducted a laboratory model test on behalf of the Swedish National Rail Administration (now the Swedish Transport Administration). The laboratory model test aimed to find a method to determine the expected temperature conditions along a tunnel to decide which parts of the tunnel require frost insulation to protect the drainage system from freezing and prevent ice formation. To evaluate the laboratory model test, the Swedish Transport Administration in collaboration with Luleå University of Technology have performed field surveys in two Swedish railway tunnels. The field measurements involved monitoring temperatures in air, rock surfaces and rock mass, as well as measuring wind direction, wind and air velocity and air pressure. The measurements in the tunnels show that the frost penetrates further into the tunnels than was expected from the laboratory model test, which was based on a completely uninsulated tunnel. Frost insulated drains do not only prevent the cold air from reaching the rock mass, but also prevent the rock from emitting geothermal heat that warms up the cold tunnel air. Consequently, the frost penetrates further into the tunnel than it would do if the heat from the rock mass was allowed to warm up the outside air on its way into the tunnel. The number of frost insulated drains and how much of the tunnel walls and roof are covered thereby affect the length of the frost penetration.

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  • 9.
    Andrén, Anna
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. The Swedish Transport Administration, Borlänge, Sweden.
    Dahlström, Lars-Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Field Observations of Water and Ice Problems in Railway Tunnels from a Maintenance Perspective2023In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 13, no 1, p. 11-54Article in journal (Refereed)
    Abstract [en]

    During the winter season, ice causes major problems in many Swedish railway tunnels. Ice, rock and shotcrete in the roof and on the walls may come loose and fall down, installations and cables can break due to ice loads and the tracks can become covered with ice. To maintain safety and prevent traffic disturbances, many tunnels require frequent maintenance. The removal of ice, loose rock and shotcrete is expensive and potentially risky work for the maintenance workers. To reduce maintenance costs, it is important to improve our knowledge of frost penetration inside tunnels and investigate the effect of ice pressure and frost shattering on loadbearing constructions. The aim of this investigation was to gather information about the problems caused by water leakage and its effect on the degradation of a rock tunnel when subjected to freezing temperatures. There are many factors that determine whether frost or ice formations will appear in tunnels. To collect information on ice formation problems, field observations were undertaken in five of Sweden’s railway tunnels between autumn 2004 and summer 2005. For one of the tunnels, follow-up observations also took place in March during the years 2005, 2006 and 2007.

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  • 10.
    Andrén, Anna
    et al.
    The Swedish Transport Administration, Borlänge, Sweden.
    Dahlström, Lars-Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Temperature Flows in Railway Tunnels: Field Measurements of Frost Penetration2020In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 10, no 5, p. 161-194Article in journal (Refereed)
    Abstract [en]

    Even though extensive pre-grouting is carried out during the construction of tunnels, certain leakages and drips remain. These remaining leakages are remedied by a combination of post-injection and drainage measures with, for example, frost insulated drain mats, whose function is to prevent the cold tunnel air from reaching a leakage spot and causing water to freeze. Despite these measures, some water may still enter the tunnels and cause problems during winter with ice formations and frost shattering. Icicles, ice pillars and ice-covered roads and railway tracks require constant maintenance. If ice occurs in the fracture network close to the tunnel contour or in the interface between the rock and shotcrete, it can cause degradation of the load-bearing capacity of the tunnel and fall-outs of both materials. In tunnel sections with water leakage problems it is common to protect the load-bearing structure from freezing with insulated drainage systems. To determine where along the tunnel efforts must be made to prevent ice formation, the temperature conditions of tunnels must be investigated. This article presents parts of the results from field measurements in two Swedish railway tunnels. The measurements involves monitoring of air and rock temperatures, air pressure and air velocity.

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  • 11.
    Arredondo, Cesar
    et al.
    University of Chile.
    Montes Atenas, Gonzalo
    University of Chile.
    Kampmann, Tobias Christoph
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Casali, Aldo
    University of Chile.
    Valencia, Alvaro
    University of Chile.
    Firsching, Markus
    Fraunhofer Development Centre X-ray Technology EZRT, Fürth, Germany.
    Valenzuela, Fernando
    University of Chile.
    Insights on the application and evaluation of ore sorting technologies in mining operations: A critical review2021In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444Article in journal (Refereed)
  • 12. Arvanitidis, Ioannis
    et al.
    Nyberg, Ulf
    Ouchterlony, Finn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Diameterns inverkan på detonationsegenskaperna hos emulsionssprängämne E682 i cylinderprovet2004Report (Other academic)
    Abstract [en]

    Cylinder expansions tests with 4 different diameters ranging from 40 to 100 mm have been conducted on the generic emulsion explosive E682, both pure and with 20 % ANFO content. The work capacity is expressed in terms of the Gurney energy EG, which equals the sum of the kinetic energy of the copper tube and the radial kinetic energy of the gases. The purpose was to study the effect of charge diameter on the explosive's work capacity expressed as the Gurney energy and to supplement earlier work done by Nie (2001). The radial expansion has been measured as well as the velocity of detonation in 11 copper tubes. The effect of ANFO granules were tested by making a mixture of E682 with 20% ANFO. The ANFO used in the present study is Anolit from Dyno Nobel, which basically is the same product as the Prillit A used by Nie. The average density of pure E682 was 1130 kg/m3 and that of E682 with 20% ANFO 1200 kg/m3. The results from the new batch of E682 show similarities with the old batch regarding VOD as function of inverse charge diameter but the trend of the Gurney energy is different from the first experiments carried out by Nie. This could be due to previous tolerance variations in the tube dimensions. The Gurney energy seems to be independent of the charge diameter between 40-100 mm in the new experiments. The measured Gurney energy for pure E682 was 1.77 ± 0.06 MJ/kg and that of E682 with 20% ANFO 1.71 ± 0.07 MJ/kg which is somewhat lower. The use of 20% ANFO in E682 results in the same volume based Gurney energy as for pure E682 however. The overall average is 2.02 ± 0.02 MJ/dm3. The energy utilisation ratio is 0.58 ± 0.03 for pure E682 and 0.53 ± 0.03 for E682 with 20% ANFO. This is slightly lower than for the Titan 6000 series gassed bulk emulsion but higher than for pure ANFO. The detonation pressure decreases with the charge diameter however and this indicates that a smaller hole diameter in rock blasting leads to a lower detonation pressure without loosing work energy when keeping the powder factor constant.

  • 13.
    Asghari, M.
    et al.
    University of Tehran, Tehran, Iran.
    Noaparast, M.
    University of Tehran, Tehran, Iran.
    Shafaie, S. Z.
    University of Tehran, Tehran, Iran.
    Ghassa, S.
    University of Tehran, Tehran, Iran.
    Chelgani, Saeed Chehreh
    University of Michigan, Ann Arbor, USA.
    Recovery of coal particles from a tailing dam for environmental protection and economical beneficiations2018In: International Journal of Coal Science & Technology, ISSN 2095-8293Article in journal (Refereed)
    Abstract [en]

    Considerable amounts of coal particles are accumulated in the tailing dams of washing plants which can make serious environmental problems. Recovery of these particles from tailings has economically and environmentally several advantages. Maintaining natural resources and reducing discharges to the dams are the most important ones. This study was examined the possibility to recover coal particles from a tailing dam with 56.29% ash content by using series of processing techniques. For this purpose, gravity separation (jig, shaking table and spiral) and flotation tests were conducted to upgrade products. Based the optimum value of these processing methods, a flowsheet was designed to increase the rate of recovery for a wide range of coal particles. Results indicated that the designed circuit can recover over 90% of value coal particles and reduce ash content of product to less than 14%. These results can potentially be used for designing an industrial operation as a recycling plant and an appropriate instance for other areas to reduce the environmental issues of coal tailing dams.

  • 14.
    Asimi Neisiani, A.
    et al.
    Department of Mining and Metallurgical Engineering Yazd University, Yazd 89195-741, Iran.
    Saneie, R.
    Department of Materials Engineering, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
    Mohammadzadeh, A.
    School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran.
    Wonyen, D. G.
    Department of Material Science and Engineering (Mining and Mineral Processing Engineering), African University of Science and Technology Abuja, Nigeria.
    Chelgani, Saeed Chehreh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Biodegradable hematite depressants for green flotation separation – An overview2023In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 199, article id 108114Article, review/survey (Refereed)
    Abstract [en]

    Due to environmental issues and the restrictions imposed on mineral flotation separation, the use of biodegradable and environmentally friendly reagents has gained widespread international attention. So far, several investigations have been conducted regarding the eco-friendly flotation separation of iron oxide ores for moving toward sustainable development and cleaner production. Yet, no critical review is specified on the green and eco-friendly depression reagents through their reverse flotation beneficiation. Therefore, this study will comprehensively discuss the previously conducted works in this area and provides suggestions for future assessments and developments. This robust study explored various adsorption aspects of natural-based depressants (polysaccharide-, polyphenolic-, and lignosulfonate-based) on iron oxide minerals (mainly hematite) to create a possible universal trend for each biodegradable depressant derivative. The laboratory and industrial experiments indicated that these depressants (except lignosulfonate-based) could selectively depress hematite at alkaline pHs and enhance its reverse flotation separation from their gangue phases (especially silicates as the main gangue phases). Although these eco-friendly depressants showed promising metallurgical results, several gaps still need to be addressed, notably in surface analyses and their adsorption mechanisms.

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  • 15.
    Asimi Neisiani, Ali
    et al.
    Department of Mining and Metallurgical Engineering, Yazd University, Yazd, Iran.
    Chehreh Chelgani, Saeed
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Biodegradable acids for pyrite depression and green flotation separation–an overview2023In: Critical reviews in biotechnology, ISSN 0738-8551, E-ISSN 1549-7801Article, review/survey (Refereed)
    Abstract [en]

    Exponential increasing demands for base metals have made meaningful processing of their quite low-grade (>1%) resources. Froth flotation is the most important physicochemical pretreatment technique for processing low-grade sulfide ores. In other words, flotation separation can effectively upgrade finely liberated base metal sulfides based on their surface properties. Various sulfide surface characters can be modified by flotation surfactants (collectors, activators, depressants, pH regulators, frothers, etc.). However, these reagents are mostly toxic. Therefore, using biodegradable flotation reagents would be essential for a green transition of ore treatment plants, while flotation circuits deal with massive volumes of water and materials. Pyrite, the most abundant sulfide mineral, is frequently associated with valuable minerals as a troublesome gangue. It causes severe technical and environmental difficulties. Thus, pyrite should be removed early in the beneficiation process to minimize its problematic issues. Recently, conventional inorganic pyrite depressants (such as cyanide, lime, and sulfur-oxy compounds) have been successfully assisted or even replaced with eco-friendly and green reagents (including polysaccharide-based substances and biodegradable acids). Yet, no comprehensive review is specified on the biodegradable acid depression reagents (such as tannic, lactic, humic acids, etc.) for pyrite removal through flotation separation. This study has comprehensively reviewed the previously conducted investigations in this area and provides suggestions for future assessments and developments. This robust review has systematically explored depression performance, various adsorption mechanisms, and aspects of these reagents on pyrite surfaces. Furthermore, factors affecting their efficiency were analyzed, and gaps within each area were highlighted.

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  • 16.
    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.

  • 17.
    Atta, Khalid Tourkey
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Euzébio, Thiago
    Instituto Tecnológico Vale.
    Ibarra, Haroldo
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Silva Moreira, Vinicius
    Vale S.A..
    Johansson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Extension, Validation, and Simulation of a Cone Crusher Model2019In: 18th IFAC Symposium on Control, Optimization and Automation in Mining, Mineral and Metal Processing, MMM 2019: Stellenbosch, South Africa, 28–30 August 2019 / [ed] Lidia Auret, Elsevier, 2019, p. 1-6Conference paper (Refereed)
    Abstract [en]

    This work presents an extension and validation for a control oriented model of cone crushers. Compared to earlier work, the aspect of energy consumption was added to the model. Validation was carried out using measurement data from two different crusher models and was based both on laboratory data and field experiment data. Using the results from the field trials, a plant simulator for a secondary crushing circuit has been implemented.

  • 18.
    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.

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  • 19.
    Bengtsson, Margaretha
    et al.
    Svenskt stål AB, SSAB, Oxelösund, Sweden.
    McPhail, Alex
    G. W. Wilkinson & Sons Ltd, Leeds, England.
    Karlsson, Gunder
    Royal Institute of Technology, Stockholm, Sweden.
    Olsson, Marianne
    SUPRA AB, Landskrona, Sweden.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Carlson, Roy
    Vattenfallsverket, Stockholm, Sweden.
    The Importance Of Coal In Swedish Iron Production1980In: Jernkontorets annaler med Bergsmannen : JkA : tidskrift för nordisk bergshantering, ISSN 0348-6559, Vol. 164, no 3, p. 61-61Article in journal (Refereed)
  • 20.
    Bergamo, Pedro A. de S.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Izart, Caroline
    Metso Outotec Oy, Rauhalanpuisto 9, 02230 Espoo, Finland.
    Streng, Emilia S.
    Aalto University, 02150 Espoo, Finland.
    Rosenkranz, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Ghorbani, Yousef
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Use of Kirkpatrick evaluation model in simulation-based trainings for the mining industry - A case study for froth flotation2022In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 188, article id 107825Article in journal (Refereed)
    Abstract [en]

    Trainings play a vital role in the transference of knowledge between skilled and novice operators in the mineral industry. Evaluation is an important part of those trainings, but many trainings rely solely on the trainees’ feedback. This paper presents how technology enhancement can help produce more effective training evaluations to the mineral industry. It describes a case study involving a froth flotation simulator-based training, including details of the simulation, user interface, and the training program. The training was delivered to sixteen mining operators and evaluated by both the traditional method (trainee&apos;s feedback) and with the simulation&apos;s learning evaluation. The feedback evaluation showed a high level of satisfaction with the learning results, while the learning evaluation showed a very different training outcome, putting established evaluation methods such as Kirckpatrick&apos;s “Four levels” into question. Correlations between the learning results and the operators’ personal information such as process work, and academic experience are also presented.

  • 21.
    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. 

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  • 22.
    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
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  • 23.
    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.

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  • 24.
    Bjartell, Erik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Karlsson, Per
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Salvdimensionering för vibrationsalstrande undermarksprojekt: Framtagning av beräkningsark och standardrapport2021Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [en]

    Blasting is often performed during tunnel projects and as a result, ground vibrations will occur. These vibrations depend upon several factors and can be experienced as disturbing for the surrounding area and may cause damage to buildings nearby. The guidelines published by the Swedish Institute for Standards determine the permitted magnitude of such ground vibrations, by imposing a maximum oscillation speed for any blasting works that take place in proximity of buildings. To predict vibrations during blast work, scaled factor relations can be applied. There are different kinds of scaled factor relations, but what they have in common is that they estimate the maximum oscillation speed as a function of distance between the round and measuring point, and charge per delay. As a first step, the measured vibration value has been analysed and drawn up with respect to rock foundation and tunnel nearby. Based on the dimensions of the drillhole and the density of the explosive, the charge per delay can be calculated and compiled whit the oscillation speed at a specific measuring point. Based on these values, empirical constants have been produced through regression analysis, and therefore predictions for ground vibrations at buildings on different types of rock foundations and nearby tunnel can be determined. Given these predictions, a calculation sheet and a standard report have been produced which together form a basis for future underground projects.

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    Beräkningsark
  • 25.
    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.

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  • 26.
    Botelho, Anneliese H.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Zhang, Ping
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Dineva, Savka
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Velocity amplification of obliquely incident s-wave through fractures near free-surface2019In: Rock Mechanics for Natural Resources and Infrastructure Development - Full Papers: Proceedings of the 14th International Congress on Rock Mechanics and Rock Engineering (ISRM 2019), September 13-18, 2019, Foz do Iguassu, Brazil / [ed] Sergio A.B. da Fontoura; Ricardo Jose Rocca; José Pavón Mendoza, Taylor & Francis, 2019, p. 1487-1494Conference paper (Refereed)
    Abstract [en]

    The rockfall risk due to mining-induced seismicity reduces by installing appropriate rock support to absorb the kinetic energy from a seismic event, which is calculated by assuming the mass of ejected rock and its ejection velocity. Estimation of ejection velocity is normally based on scaling laws that do not consider the effect of the excavation free-surface and existing fractures near the excavation free-surface. Field monitoring studies have shown that the peak particle velocity on the free-surface can be much larger than the velocity in deep solid rock. The interaction between the fractures and the free-surface under incident S-wave is investigated by using a two-dimensional UDEC model with fractured zone characterized as one, two, three and four sets of parallel fractures with varied intersecting angles. The results show that wave amplification factor varies according to the incident wave angle, the number of fracture sets and fracture spacing.

  • 27.
    Botelho, Anneliese H.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. CNPq - Brazil.
    Zhang, Ping
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Effects of parallel fractures near a free surface on velocity amplification of S-wave2017In: Proceedings of the Ninth International Symposium on Rockbursts and Seismicity in Mines / [ed] Javier Vallejos, Santiago do Chile: University of Chile , 2017, , p. 337Conference paper (Refereed)
    Abstract [en]

    When rock support is designed in a seismically active underground mine, it is important tochoose the right ejection velocity and calculate corresponding kinetic energy. Field monitoringand back-analyses have shown that ejection velocity of the order of 10 m/s and higher can resultfrom seismic events of moderate magnitude. Such velocities are much higher than those predictedusing peak particle velocity (PPV) obtained from scaling laws. Many researches have reportedthe amplification of particle velocity near excavation surface. Velocity amplification of P-wavetravelling through fractured rock near a free surface was recently studied. The amplification ofseismic waves on the skin of excavation is of interest in case of large seismic events. Seismic eventswith large magnitude are often associated with slip along weaknesses or shear fracturing of intactrock, which according to observations radiate much stronger S-wave as compared to P-wave.In this paper, velocity amplification of S-wave was investigated by modelling the dynamicinteraction between fractured rock and a free surface using a 2D discontinuum-based numericalprogram, UDEC (Universal Distinct Element Code). A 1D model with a fractured zone wasused to represent the fractured rock in this investigation. It is found that the shear stress ratio,wave frequency, fracture stifness, fracture spacing and thickness of fractured zone afect thevelocity amplification, in which the shear stress ratio is the most crucial factor influencing wavetransmission. The results have proved that the interaction of the seismic wave and multiplefractures near the free surface strongly influences the ground motion.

  • 28.
    Bu, Xiangning
    et al.
    School of Chemical Engineering and Technology, China University of Mining and Technology, Jiangsu, Xuzhou, 221116, China.
    Taghizadeh Vahed, Amir
    EPosture AB Luleå, Kvartsstigen 6, SE-977 53, Sweden.
    Ghassa, Sina
    School of Mining, College of Engineering, University of Tehran, Tehran, 16846-13114, Iran.
    Chelgani, Saeed Chehreh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Modelling of coal flotation responses based on operational conditions by random forest2021In: International Journal of Oil, Gas and Coal Technology, ISSN 1753-3309, E-ISSN 1753-3317, Vol. 27, no 4, p. 457-468Article in journal (Refereed)
    Abstract [en]

    Coal consumption is one of the critical factors in the economy of China. Flotation separation of coal from its inorganic part (ash) can reduce environmental problems of coal consumption and improve its combustion. This investigation used random forest (RF) as an advanced machine learning method to rank flotation operations by variable importance measurement and predict flotation responses based on operational parameters. Fifty flotation experiments were designed, and performed based on various flotation conditions and by different variables (collector dosage, frother dosage, air flowrate, pulp density, and impeller speed). Statistical assessments indicated that there is a significant negative correlation between yield and ash content. Experiments indicated that in the optimum conditions, yield and ash content would be 80 and 9%, respectively. Variable importance measurement by RF showed that frother has the highest effectiveness on yield. Outcomes of modelling released that RF can accurately be used for ranking flotation parameters, and generating models within complex systems in mineral processing.

  • 29.
    Bu, Xiangning
    et al.
    Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China.
    Zhou, Shaoqi
    Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China.
    Sun, Meng
    Fengxian Power Supply Co., Ltd., State Grid Jiangsu Electric Power Co., Ltd., Fengxian, Jiangsu 221700, China.
    Alheshibri, Muidh
    Department of Basic Science, Deanship of Preparatory Year and Supporting Studies, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31441, Saudi Arabia; Basic & Applied Scientific Research Center, Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31441, Saudi Arabia.
    Shakhaoath Khan, Md.
    ARC Research Hub for Computational Particle Technology, Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia.
    Xie, Guangyuan
    Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education, School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China.
    Chelgani, Saeed Chehreh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Exploring the Relationships between Gas Dispersion Parameters and Differential Pressure Fluctuations in a Column Flotation2021In: ACS Omega, E-ISSN 2470-1343, Vol. 6, no 34, p. 21900-21908Article in journal (Refereed)
    Abstract [en]

    Flotation separation, which is the most important mineral beneficiation technique, is dependent on gas dispersion (hydrodynamic conditions). Thus, many investigations have focused on the precise determination of hydrodynamic conditions such as Reynolds number of the bubbles, bubble velocity, and bubble diameter. However, few studies have examined their relationships with pressure fluctuations in a column flotation. This study introduced the differential pressure fluctuations as an actual variable that could be considered to determine the collection zone’s hydrodynamic conditions in a cyclonic microbubble flotation column. In general, the outcomes indicated that superficial gas velocity had the most substantial relationship with the differential pressure fluctuations among other flotation factors (such as pump speed, superficial gas velocity, superficial water velocity, and frother dosage). Furthermore, a high coefficient of determination (R2 > 0.77) for the equation generated to assess the relationships demonstrated that differential pressure fluctuations could be used as a promising tool to determine the hydrodynamic parameters’ characteristics in the flotation columns. 

  • 30.
    Burnett, Mark
    et al.
    AMC Consultants Limited, UK.
    Zhang, Steven E.
    PG Techno Wox (SmartMin).
    Ghorbani, Yousef
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Bourdeau, Julie E.
    PG Techno Wox (SmartMin).
    Steiner, Benedikt M.
    Has 11 years of global experience in project generation. He has an MSc from the Royal School of Mines, London, and a PhD from the University of Exeter. He is currently Director of the Master's Programme in Exploration and Mining Geology at the, Camborne School of Mines, UK.
    Barnet, James S. K.
    St Andrews, Scotland.
    Nwaila, Glen T.
    University of the Witwatersrand.
    Development of mineral supply and demand from 1950 to 2020: Cold War and consumerism2022In: Routledge Handbook of the Extractive Industries and Sustainable Development / [ed] Natalia Yakovleva; Edmund Nickless, Taylor & Francis Group, 2022, p. 34-60Chapter in book (Other academic)
    Abstract [en]

    The supply and demand of minerals from 1950 to 2020 is examined by focusing on known causal relationships and historical drivers such as the Cold War, and how these have impacted the supply and demand of minerals. The complex, and often fascinating, events that have influenced supply and demand in the minerals market, including geopolitics, environmental policy, high-tech modernization, and the COVID-19 pandemic are reviewed. The examples we provide, focus on the primary consumers in the minerals market, including America, the European Union (EU), and the BRICS (Brazil, Russia, India, China, and South Africa) nations. Fundamental drivers such as sustainability, national defence, and technology are also discussed. This chapter begins with an integrated highlight of the major developments from 1950 to 2020 and then expands on the subject matter in a decadal fashion, providing additional context and detail on the forces and events which have influenced mineral supply and consumption trends.

  • 31.
    Chelgani, S. Chehreh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Nasiri, H.
    Department of Computer Engineering, Amirkabir University of Technology, Tehran, Iran.
    Alidokht, M.
    Tabas Parvardeh Coal Company (TPCCO), Birjand, Iran.
    Interpretable modeling of metallurgical responses for an industrial coal column flotation circuit by XGBoost and SHAP-A “conscious-lab” development2021In: International Journal of Mining Science and Technology, ISSN 2095-2686, Vol. 31, no 6, p. 1135-1144Article in journal (Refereed)
    Abstract [en]

    Surprisingly, no investigation has been explored relationships between operating variables and metallurgical responses of coal column flotation (CF) circuits based on industrial databases for under operation plants. As a novel approach, this study implemented a conscious-lab “CL” for filling this gap. In this approach, for developing the CL dedicated to an industrial CF circuit, SHapley Additive exPlanations (SHAP) and extreme gradient boosting (XGBoost) were powerful unique machine learning systems for the first time considered. These explainable artificial intelligence models could effectively convert the dataset to a basis that improves human capabilities for better understanding, reasoning, and planning the unit. SHAP could provide precise multivariable correlation assessments between the CF dataset by using the Tabas Parvadeh coal plant (Kerman, Iran), and showed the importance of solid percentage and washing water on the metallurgical responses of the coal CF circuit. XGBoost could predict metallurgical responses (R-square > 0.88) based on operating variables that showed quite higher accuracy than typical modeling methods (Random Forest and support vector regression).

  • 32.
    Chelgani, Saeed Chehreh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Estimation of gross calorific value based on coal analysis using an explainable artificial intelligence2021In: Machine Learning with Applications, ISSN 2666-8270, Vol. 6, article id 100116Article in journal (Refereed)
    Abstract [en]

    Developing fuel resources is strategically crucial for Armenia. Far more than any other fossil fuel resource, coal roughly generates half the nation’s electricity. Although coal could play a critical role, no vast data is available about Armenia coal properties. Using robust modeling of energy indexes such as coal gross calorific value (GCV) by considering trivial existing datasets could be an essential clue for ensuring sustainable development. For the first time, this investigation is going to model GCV for Armenia coal samples. For this purpose, SHAP (SHapley Additive exPlanations) as a novel explainable artificial intelligence will be introduced. SHAP enables understanding the magnitude of relationships between each individual input record and its representative output and ranks input variables based on their effectiveness. SHAP was coupled by extreme gradient boosting (xgboost) as the most recently generated powerful predictive machine learning tool (SHAP-Xgboost). SHAP-Xgboost could accurately (R2=0.99) model GCV based on proximate and ultimate variables of Armenia coal samples. These significant outcomes open a new window for developing high interpretability models to assess coal properties and pinpoint the influential parameters.

  • 33.
    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.

  • 34.
    Chelgani, Saeed Chehreh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Hadavandi, Esmaeil
    Department of Industrial Engineering, Birjand University of Technology, Birjand, Iran.
    Hower, James C.
    Center for Applied Energy Research, University of Kentucky, Lexington, KY, USA.
    Estimation of heavy and light rare earth elements of coal by intelligent methods2021In: Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, ISSN 1556-7036, E-ISSN 1556-7230, Vol. 43, no 1, p. 70-79Article in journal (Refereed)
    Abstract [en]

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

  • 35.
    Chelgani, Saeed Chehreh
    et al.
    University of Michigan, Ann Arbor, USA.
    Hart, B.
    University of Western Ontario, Ontario N6G0J3, Canada.
    Explaining surface interactions for common associated gangues of rare earth minerals in response to the oxalic acid2018In: International Journal of Mining Science and Technology, ISSN 2095-2686, Vol. 28, no 2, p. 343-346Article in journal (Refereed)
    Abstract [en]

    In the flotation of rare earth minerals (REMs), oxalic acid is reportedly acting both as a depressant and pH modifier. Although results of testing have established the significance of oxalic acid in the flotation process, its specific role in either the recovery or selectivity of REMs over their common gangue minerals is not well understood. Pulp pH reduction trials with alternative acids have not shown the same effect on the REMs recovery or the depression of gangue phases. This work studies the effect of oxalic acid on the surface of common REMs gangue minerals (quartz and carbonates (dolomite and calcite)) in a series of conditioning tests. Gangue surface analyses by time of flight secondary ion mass spectroscopy (TOF-SIMS) indicate that oxalic acid inhibits the transfer of secondary ions generated during the conditioning process from one mineral to another. In this regard, the oxalate anion acts to fix ions in solution through chelation, limiting their participation in surface adsorption.

  • 36.
    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.

  • 37.
    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.

  • 38.
    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.

  • 39.
    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.

  • 40.
    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.

  • 41.
    Chelgani, Saeed Chehreh
    et al.
    University of Michigan, Ann Arbor, Michigan, USA.
    Hower, James C.
    University of Kentucky, Lexington, USA.
    Estimating REY content of eastern Kentucky coal samples based on their associated ash elements2018In: Journal of Rare Earths, ISSN 1002-0721, E-ISSN 2509-4963, Vol. 36, no 11, p. 1234-1238Article in journal (Refereed)
    Abstract [en]

    Coal and coal combustion byproducts can be considered as an alternative source of rare earth elements and yttrium (REY). The study of relationships between REY and other main coal properties could have several advantages such as estimating REY content of coal particles and designing beneficial extraction method. In this investigation, inter-correlations between REY content with coal parameters (proximate and ash elements) for a wide range of eastern Kentucky coal samples (708 records) were explored. Results demonstrate that zircon and monazite are the main source of heavy and light rare earth elements (HREE and LREE), respectively. Zr has the highest correlation with Y and Th has the strength relationship with Ce and La. In general, LREE have higher interaction with coal ash content in comparison with HREE. Results indicated that REY can be estimated quite satisfactorily by using their associated elements in coal ash.

  • 42.
    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.

  • 43.
    Chelgani, Saeed Chehreh
    et al.
    Helmholtz Institute Freiberg for Resource Technology, Freiberg, Germany.
    Leißner, T.
    TU Bergakademie Freiberg, Freiberg, Germany.
    Rudolph, M.
    Helmholtz Institute Freiberg for Resource Technology, Freiberg, Germany; TU Bergakademie Freiberg, Freiberg, Germany.
    Peuker, U. A.
    TU Bergakademie Freiberg, Freiberg, Germany.
    Study of the relationship between zinnwaldite chemical composition and magnetic susceptibility2015In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 72, p. 27-30Article in journal (Refereed)
    Abstract [en]

    This study investigates the relationship between chemical analyses and magnetic susceptibility of zinnwaldite through magnetic separation of various size fractions. Statistical analyses were used to increase information about magnetic properties of this mineral as a future source of lithium. Statistical modeling indicated that magnetic susceptibility (as a main factor of magnetic separation) accurately can be predicted based on cations content of zinnwaldite. However the size of particles had a significant effect on magnetic susceptibility. The small difference between the estimated and measured values for the non-linear relationship of this prediction (less than 1 (10−8 m3/kg)) shows that these accurate theoretical techniques can be also applied to estimate magnetic properties of zinnwaldite in other resources, and in-situ analysis.

  • 44.
    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.

  • 45.
    Chelgani, Saeed Chehreh
    et al.
    University of Michigan, Ann Arbor, USA; Islamic Azad University, Islamshahr, Iran.
    Matin, S. S.
    University of Michigan, Ann Arbor, USA; Islamic Azad University, Islamshahr, Iran.
    Study the relationship between coal properties with Gieseler plasticity parameters by random forest2018In: International Journal of Oil, Gas and Coal Technology, ISSN 1753-3309, E-ISSN 1753-3317, Vol. 17, no 1, p. 113-127Article in journal (Refereed)
    Abstract [en]

    Gieseler fluidity provides thermoplastic information and the compatibility of blended coals for the cokemaking. A novel soft computing method, random forest (RF), for prediction of the softening temperature (Ts), the temperature of maximum fluidity (Tf), resolidification temperature (Tr) and maximum fluidity (MF) [Gieseler parameters (Gp)] was conducted based on the coal proximate analysis. Variable importance measurements were performed by RF to select the most effective variables for the prediction of Gp. Selected variables have been used as an input set of RF model for the modelling and prediction. Results of models indicated that RF can provide a satisfactory prediction of Gp with the correlation of determination R2: 0.64, 0.82, 0.90, and 0.86 for Ts, Tf, Tr and MF, respectively. Based on these results, it can be proposed that RF as a reliable non-parametric reliable predictive tool can be used for modelling of complex relationships in the fuel and energy investigations. 

  • 46.
    Chelgani, Saeed Chehreh
    et al.
    University of Michigan, Ann Arbor, Michigan, USA.
    Matin, S. S.
    Islamic Azad University, Tehran, Iran.
    Hower, James C.
    University of Kentucky, Lexington, Kentucky, USA.
    Explaining relationships between coke quality index and coal properties by Random Forest method2016In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 182, p. 754-760Article in journal (Refereed)
    Abstract [en]

    In this study was shown that random forest (RF) can be used as a sensible new data mining tool for variable importance measurements (VIMs) through various coal properties for prediction of coke quality (Free Swelling Index (FSI)). The VIMs of RF within coal analyses (proximate, ultimate, and petrographic analyses) were applied for the selection of the best predictors of FSI over a wide range of Kentucky coal samples. VIMs assisted by Pearson correlation through proximate, ultimate, and petrographic analyses indicated that volatile matter, carbon, vitrinite, and Rmax (coal rank parameters) are the most effective variables for the prediction of FSI. These important predictors have been used as inputs of RF model for the FSI prediction. Outputs in the testing stage of the model indicated that RF can predict FSI quite satisfactorily; the R2 was 0.93 and mean square error from actual FSIs was 0.15 (had less than interval unit of FSI; 0.5). According to the result, by providing nonlinear inter-dependence approximation among parameters for variable selection and also non-parametric predictive model RF can potentially be further employed as a reliable and accurate technique for the determination of complex relationship through fuel and energy investigations.

  • 47.
    Chelgani, Saeed Chehreh
    et al.
    University of Michigan, Ann Arbor, Michigan, USA.
    Matin, S. S.
    Islamic Azad University, Tehran, Iran.
    Makaremi, S.
    McMaster University, ON, Canada.
    Modeling of Free Swelling Index Based on Variable Importance Measurements of Parent Coal Properties by Random Forest Method2016In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 94, p. 416-422Article in journal (Refereed)
    Abstract [en]

    Coke quality has a critical role in the steelmaking industry. The aim of this study is to examine the complex relationships between various conventional coal analyses using coke making index “free swelling index (FSI)”. Random forest (RF) associated with variable importance measurements (VIMs), which is a new powerful statistical data mining approach, is utilized in this study to analyze a high-dimensional database (3961 samples) to rank variables, and to develop an accurate FSI predictive model based on the most important variables. VIMs was performed on various types of analyses which indicated that volatile matter, carbon, moisture (coal rank parameters) and organic sulfur are the most effective coal properties for the prediction of FSI. These variables have been used as an input set of RF model for the FSI modeling and prediction. Results of FSI model indicated that RF can provide a satisfactory prediction of FSI with the correlation of determination R2 = 0.96 and mean square error of 0.16 from laboratory FSIs (which is smaller than the interval unit of FSI; 0.5). Based on this result, RF can be used to rank and select effective variables by evaluating nonlinear relationships among parameters. Moreover, it can be further employed as a non-parametric reliable predictive method for modeling, controlling, and optimizing complex variables; which to our knowledge has never been utilized in the fuel and energy sectors.

  • 48.
    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.

  • 49.
    Chelgani, Saeed Chehreh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Nasiri, H.
    Department of Computer Engineering, Amirkabir University of Technology, Tehran, Iran.
    Tohry, A.
    Mining and Metallurgical Engineering Department, Yazd University, Yazd, Iran; Research and Development Unit, Rahbar Farayand Arya Company (RFACo), Tehran, Iran.
    Modeling of particle sizes for industrial HPGR products by a unique explainable AI tool- A “Conscious Lab” development2021In: Advanced Powder Technology, ISSN 0921-8831, E-ISSN 1568-5527, Vol. 32, no 11, p. 4141-4148Article in journal (Refereed)
    Abstract [en]

    High-Pressure Grinding Rolls (HPGR), as a modified type of roll crushers, could intensively reduce the energy consumptions in the mineral processing comminution units. However, several problems counted for their operational modeling, especially in the industrial scales. Expanding a conscious laboratory (CL) as a recently developed concept based on the recorded datasets from the HPGR operational variables could be tackled those complications and fill the gap. Moreover, constructing such a CL base on explainable artificial intelligence (EAI) systems would be an innovative point for the digitalizing powder technology industries. Using a robust EAI model as a strategic approach could significantly improve system transparency and trustworthiness to convert any complicated black-box machine learning to a logical human basis system. This study introduced the SHapley Additive exPlanations (SHAP) and extreme gradient boosting (XGBoost) as the latest powerful EAI tool for the CL modeling of the particle sizes produced by an industrial HPGR (P80) in the Fakoor Sanat iron ore processing plant (Kerman, Iran). SHAP precisely assessed multivariable relationships between the monitored operational variables and correlated them with the HPGR P80. SHAP values showed relationship magnitudes among variables and ranked them based on their effectiveness on the P80 prediction. The working gap demonstrated the highest importance for the P80 prediction. XGBoost could precisely predict the P80 and showed higher accuracy than typical machine learning methods (random forest and support vector regression) for constructing the CL of HPGR. These significant outcomes would open a new window for robust consideration of the EAI models within powder technology.

  • 50.
    Chelgani, Saeed Chehreh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Nasiri, H.
    Department of Computer Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran.
    Tohry, A.
    Research and development unit, Rahbar Farayand Arya Company (RFACo), Tehran, Iran.
    Heidari, H. R.
    Deputy of the operation and production, Rahbar Farayand Arya Company (RFACo), Tehran, Iran.
    Modeling industrial hydrocyclone operational variables by SHAP-CatBoost - A "conscious lab" approach2023In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 420, article id 118416Article in journal (Refereed)
    Abstract [en]

    Undoubtedly hydrocyclones play a critical role in powder technology, which can considerably affect the plants&apos; process efficiency. However, hydrocyclones were rarely modeled on an industrial scale, where a model can be used to train operators and minimize potential scale-up errors and lab costs. The novel approach for filling such a gap would be using conscious lab "CL" as a new concept that builds based on an industrial dataset and explainable artificial intelligence (XAI). As a novel approach, this study developed a CL and explored the interactions between hydrocyclone variables by the most recent XAI method called "SHapley Additive exPlanations (SHAP)", and a novel machine-learning model, "CatBoost". The hydrocyclone output and the particle size of the plant magnetic separator were modeled by SHAP-CatBoost. SHAP could successfully model all the relationships, and CatBoost could predict the O80 and K80, where outcomes had a higher accuracy (R2 similar to 0.90) than other conventional AIs.

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