References of "Gaydardzhiev, Stoyan"
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See detailCEReS Deliverable 4.3: Extractive Metallurgy Unit Development Report
Arinanda, Muhammad ULiege; Gaydardzhiev, Stoyan ULiege

Report (2019)

WP4 Char Leaching aims to demonstrate the feasibility for utilisation of the acidic leachates (biolixiviant) generated from coal wastes bioleaching (WP3) as leaching agent for extraction of the base and ... [more ▼]

WP4 Char Leaching aims to demonstrate the feasibility for utilisation of the acidic leachates (biolixiviant) generated from coal wastes bioleaching (WP3) as leaching agent for extraction of the base and high-value metals contained in the char originating from the pyrolysis of PCB’s (WP2). The main tasks of this WP consist of three components: 1) investigation on the suitable reactor design and its working parameters for treating such material, which is unique compared to conventional materials treated in (bio)hydrometallurgy reactors, e.g. mineral ores, PCBs, etc., 2) exploring the option to extract metal(s) of interest and recover it/them to obtain a high-purity product, and 3) exploring the option to valorise the residue and excess iron in the char treatment system. Stirred-tank reactor (STR) is the most commonly employed since the early days of biohydrometallurgy campaigns, ranging from lab-scale to industries, treating from mineral ores to electronic wastes and residues. The main advantage of this type of reactor is achieving the desired levels of mass transfer, mixing, and agitation, in which STR outperforms other types of reactors. Due to that, STR has been given priority during WP4 of CEReS project. Despite the advantages, STR faces the challenge linked to the char’s special physical characteristics. The disintegration of fibres followed by their suspension inside reactor needs a careful hydrodynamic design to maintain sustained mixing and mass transfer. Moreover, the high shear stress of impeller rotation may harm the presence of biofilm, risking the elimination of microorganisms from the biolixiviant. As an alternative, leaching performance of rotary-drum reactor (RDR) has also been studied in this WP4. Step-leaching has also been studied in order to outline the possibility to increase the kinetic rate of copper dissolution by doing the leaching in several successive steps. Different from mineral ores, char (or pyrolyzed PCBs) contains various metals and elements, oftentimes in high grades. More often than not, the leaching of the char is non-selective, meaning that other than metals of interest, the un-desired ones should also be dissolved at high concentration. This is proven to be problematic for recovery stage, thus highlight the importance of extraction stage as intermediate between leaching and recovery. The solvent extraction stage consists of two steps; extraction step to transfer metal ions from solution (aqueous) to extractant (organic), and stripping step to transfer metal ions back from organic to aqueous. Concentrated metal ions in the aqueous phase are then transferred to recovery stage to produce metal product with high purity. This report will subsequently summarize the result on investigation of solvent extraction to produce concentrated electrolyte solution, followed by the results on recovery stage by electrowinning to produce metal product. The treatment of residues came after the char leaching and solvent extraction-electrowinning occurred. The residue from char leaching still contains fairly high grade of precious metals (gold, silver) as well as platinum group metals (PGMs). Although the processing of such by-products is not in the scope of CEReS, the possibility of such treatment has been explored in relation to CEReS applying the concept of biohydrometallurgy. The bleeding of iron from the system is important to maintain balanced level of accumulative iron from overall process, and has been explored by performing jarosite precipitation. [less ▲]

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See detailEffects of operational parameters on the bio-assisted leaching of metals from pyrolyzed printed circuit boards
Arinanda, Muhammad ULiege; van Haute, Quentin; Lambert, Fanny ULiege et al

in Minerals Engineering (2019), 134

End-of-life printed circuit boards have been subjected to proprietary pyrolysis resulting in a copper-rich char. This study details their downstream processing by hydrometallurgy for copper recovery. The ... [more ▼]

End-of-life printed circuit boards have been subjected to proprietary pyrolysis resulting in a copper-rich char. This study details their downstream processing by hydrometallurgy for copper recovery. The pyrolysed PCBs were reacted with two different bioleaching solutions containing mixed mesophilic microbial consortia and a synthetic chemical solution for comparative purposes. The influence of char pre-treatment, reactor type, working temperature, and the origin of leaching solution on the dissolution of the zero valent copper was studied. It was found, that the type of reactor had a more pronounced effect than the origin of bacterial solution in bringing copper in solution. Characterisation of the leached char confirmed the importance of the pre-treatment step. Other than ferric iron concentration and temperature, the leaching effciency and kinetics were largely influenced by the bacterial activity. The fact that copper was brought into solution by ferric iron at starting concentrations well below the stoichiometric requirement, implies bacterial regeneration of the ferric iron and its cycling in the system. [less ▲]

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See detailEffects of operational parameters on the bio-assisted leaching of metals from pyrolyzed printed circuit boards
Arinanda, Muhammad ULiege; van Haute, Quentin; Lambert, Fanny ULiege et al

in Minerals Engineering (2019), 134

End-of-life printed circuit boards have been subjected to proprietary pyrolysis resulting in a copper-rich char. This study details their downstream processing by hydrometallurgy for copper recovery. The ... [more ▼]

End-of-life printed circuit boards have been subjected to proprietary pyrolysis resulting in a copper-rich char. This study details their downstream processing by hydrometallurgy for copper recovery. The pyrolysed PCBs were reacted with two different bioleaching solutions containing mixed mesophilic microbial consortia and a synthetic chemical solution for comparative purposes. The influence of char pre-treatment, reactor type, working temperature, and the origin of leaching solution on the dissolution of the zero valent copper was studied. It was found, that the type of reactor had a more pronounced effect than the origin of bacterial solution in bringing copper in solution. Characterisation of the leached char confirmed the importance of the pre-treatment step. Other than ferric iron concentration and temperature, the leaching effciency and kinetics were largely influenced by the bacterial activity. The fact that copper was brought into solution by ferric iron at starting concentrations well below the stoichiometric requirement, implies bacterial regeneration of the ferric iron and its cycling in the system. [less ▲]

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See detailCoupling mineralogy with physicochemical parameters in view copper flotation efficiency improvement
Naumov, Dejan; Stamenov, Lachezar; Gaydardzhiev, Stoyan ULiege et al

in Physicochemical Problems of Mineral Processing (2019)

The Chelopech epithermal arsenic bearing high-sulphidation, copper-gold deposit located in Bulgaria is often considered as the richest European gold deposit. Selected physicochemical parameters have been ... [more ▼]

The Chelopech epithermal arsenic bearing high-sulphidation, copper-gold deposit located in Bulgaria is often considered as the richest European gold deposit. Selected physicochemical parameters have been measured at key flotation streams inside the processing plant. Sampling campaign has followed with samples being submitted to chemical analysis and MLA. Quantitative analysis has enabled to link copper flotation response to the type of copper bearing minerals and physiochemical parameters such as Eh, DO, EDTA extractable Cu and Fe. Data from mineral liberation analysis have highlighted an important process-relevant information explaining the variable floatability in different particle size ranges. The low chalcopyrite recovery can be linked to the non-sufficient amount of dissolved oxygen inside the copper selective flotation. Given the finely-disseminated copper bearing minerals, copper losses due to particle locking could be suggested as well. [less ▲]

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See detailInversigation on the flotation recovery of copper sulphosalts through an integrated mineralogical approach
Rincon Gamero, Jonathan Jose ULiege; Gaydardzhiev, Stoyan ULiege; Stamenov, Lachezar

in Minerals Engineering (2019), 130

Investigation on the flotation behaviour of enargite (Cu3AsS4) and tennantite ((Cu, Fe)12As4S13) during selective copper flotation was performed using an integrated mineralogical approach. To this end ... [more ▼]

Investigation on the flotation behaviour of enargite (Cu3AsS4) and tennantite ((Cu, Fe)12As4S13) during selective copper flotation was performed using an integrated mineralogical approach. To this end, samples taken from a production block at the Chelopech mine were subjected to a laboratory scale flotation and products characterized through multi-element chemical analyses and mineral mapping using a SEM-based automated mineralogy. Chemistry, modal mineralogy, copper-sulphosalts’ liberation and associations were quantified. Principal component analysis (PCA) was employed to look for relationships between mineralogical features and flotation recovery. High variability in head copper grade was observed in the studied block, with deportment results attributing it to the varied content of enargite and tennantite. Chalcopyrite content was low in the majority of the samples. The close association and the frequently observed interlocking of pyrite and Cu-sulphosalt grains can explain pyrite (and gold) recovery during copper cleaner flotation. Linear equations based on PCA results allow the prediction of Cu-sulphosalts’ recovery with a root mean square error of ±1.32%. [less ▲]

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See detailCoupling comminution indices and mineralogical features as an approach to a geometallurgical characterization of a copper ore
Rincon Gamero, Jonathan Jose ULiege; Gaydardzhiev, Stoyan ULiege; Stamenov, Lachezar

in Minerals Engineering (2019), 130

A production block of the underground mine exploiting the Chelopech high sulphidation epithermal copper-gold deposit was subjected to geometallurgical modelling. This study details the used procedure ... [more ▼]

A production block of the underground mine exploiting the Chelopech high sulphidation epithermal copper-gold deposit was subjected to geometallurgical modelling. This study details the used procedure based on traditional comminution and mineralogical indices. Drop weight and batch grinding tests were performed on representative samples to yield parameters related to Axb and operating work OWi indices. These were further correlated with the ore mineralogical features using principal component analysis. Modal mineralogy data processed by a set of linear equations has enabled the estimation of the aforementioned indices with a deviation of ±2.4 for Axb and ±9.08 kWh/t for OWi respectively. Based on ore textural characteristics and non-sulphide gangue (NSG) minerals content, two geometallurgical domains were identified as a first approach to modelling of the studied block [less ▲]

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See detailInfluence of various mechanical preparation methods of LCD on the leachability of critical elements
Nagy, Sandor; Bokanyi, Ljudmilla; Üveges, Valeria et al

in Bokanyil, Ljudmilla (Ed.) Proceedings 4 Waste Recycling XXI International Conference (2018, November)

As various electrical and electronic equipment pieces are frequently replaced due to technological development or changes, the recycling of the generating in huge amount e-wastes is of outstanding ... [more ▼]

As various electrical and electronic equipment pieces are frequently replaced due to technological development or changes, the recycling of the generating in huge amount e-wastes is of outstanding importance. The research in this field is inevitable in the spotlight of creating the circular economy. The recycling strategy is generally aiming at the recovery of materials like plastics and metals, as well as of valuable, even critical elements and compounds along with the satisfactory treatment of toxic ones. For this sake the mechanical treatment is combined with the chemical/bio/thermal techniques. Due to the numerous elements used for their manufacturing, LCD (Liquid Crystal Displays) display panels provide a wide range of valuable and critical, but also toxic elements. Thus, instead of disposal of waste LCD panels, the recovery of such elements can not only prevent possible environmental hazards but endorse the utilisation of secondary raw materials. It was proved that the mechanical pre-treatment is an important step, first of all, to recycle materials like plastics and common metals. Furthermore, the chemical mass transfer is governed by the concentration gradient, the area exposed and the retention time. Nevertheless, the presence of the “alien” components in the mass transfer can dramatically decrease the concentration gradient, the contact surface, as well as the diffusion rate. And finally, the lower the material flow to be submitted for the chemical processing, the lower the specific reagents requirement and, therefore the costs of the process (Bokányi, 2014). Thus, the mechanical removal of LCD polarizing film seems to be highly advisable; however is not easy, needs 200-250 °C high temperature as well. At the same time, the ITO (Indium-Tin-Oxide) surface layer at favourable conditions can be exposed for the diffusion even without removing polarizing foil. Therefore, one experimental series of our current research was focused on the comparison of acidic leaching of the stripped and ground LCD panel with and without the polarizing film. Another experimental series was devoted to the effect of fineness on the leachability of indium, tin and other elements. Thereafter, ground LCD was produced with different fineness in Retsch ZM 200 centrifugal mill. Based on the data obtained, important conclusions were drawn [less ▲]

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See detailPurification of a Norwegian ilmenite ore to produce synthetic rutile
Mwase Malumbo, James ULiege; Gaydardzhiev, Stoyan ULiege; Stefanescu, Eduard et al

in Chanturia, Vladimir (Ed.) Purification of a Norwegian ilmenite ore to produce synthetic rutile (2018, September 17)

The study is focused on investigating the production of synthetic rutile of 95% purity or higher from a Norwegian ilmenite ore concentrate. This was to be achieved using a sequential process involving ... [more ▼]

The study is focused on investigating the production of synthetic rutile of 95% purity or higher from a Norwegian ilmenite ore concentrate. This was to be achieved using a sequential process involving oxidative-reductive roasting at 975°C, followed by magnetic separation to further concentrate the sample and finally leaching with 20% HCl to remove mostly Fe-based impurities leaving behind synthetic rutile. The key process parameters considered were roasting time (1 and 2 hrs), leaching temperature (100, 125 and 145°C), pulp density (15 and 25wt%) and leaching time (3 and 6 hrs). The option of directly leaching the concentrate without pre-treatment was also evaluated. Test work was conducted using samples screened to a size fraction of 105-212 µm. Samples were leached in a 1 L glass autoclave. The reactor was hermetically sealed and thus the resulting pressure was not controlled but was dependent on the process temperature. The product from leaching was calcined and analysed via XRD and SEM to determine the purity of the product. The magnetic separation step was found to be ineffective and discontinued early in the study. Thus far a product with 97% synthetic rutile purity as analysed by SEM has been produced by directly leaching the concentrate at a temperature of 145°C, pulp density of 25wt% and leaching time of 6 hrs. [less ▲]

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See detailHSC SIM® simulation model of the assarel copper flotation circuit based on process mineralogy and metallurgical testing
Korolev, I.; Remes, A.; Stoilov, V. et al

in Chanturia, Vladimir (Ed.) Proceedings of the 29 International Mineral Processing Congress (2018, September)

The process modeling and simulation studies aim for better process operation and favorable environmental impact. The objective of this work is to set up a simulation model of the Assarel copper flotation ... [more ▼]

The process modeling and simulation studies aim for better process operation and favorable environmental impact. The objective of this work is to set up a simulation model of the Assarel copper flotation circuit for planning and optimization of the process with the aim of increased metal recovery. The model is parameterized based on laboratory flotation tests of ore samples from the Assarel mine together with mineralogical studies by X-ray diffraction (XRD) and Mineral Liberation Analysis (MLA). A combination of several techniques allows reliable identification of mineralogical composition of the selected samples. The changes in the proportion between sulfide minerals in various products along the circuit have been also documented. Further, this information is used in the simulation model and in data reconciliation procedures for establishing mass balance. The simulation accuracy is studied by comparing the simulations with the plant survey based mass balance. Constructed simulation model can be used to run alternative process scenarios. As an example, the flotation circuit performance with different reagent regimes is simulated based on data from batch flotation tests. Two reagents were considered for this purpose, dithiocarbamate-based one and xanthogen formate/mercaptan blend. It has been revealed that these reagents do not have the same influence on the selective flotation. The one improves flotation of gold and overall recovery but without notable selective action. In contrast, the other showed better selectivity towards copper, rejecting more gangue and lowering gold recovery. The model is also applicable for process optimization studies with different feed compositions, flowrates and circuit configurations. © IMPC 2018 - 29th International Mineral Processing Congress. All rights reserved. [less ▲]

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See detailInvestigation on Ilmenite Placer Ore as a Precursor for Synthetic Rutile
Mwase Malumbo, James ULiege; Gaydardzhiev, Stoyan ULiege; Guillet, Aurelie et al

in EMPRC 2018 European Mineral Processing and Recycling Congress Proceedings (2018, June 25)

Faced with diminished reserves of natural rutile, synthetic rutile has become an important source oftitanium used in paint and paper pigments. The study explores the influence of temperature (50, 75and ... [more ▼]

Faced with diminished reserves of natural rutile, synthetic rutile has become an important source oftitanium used in paint and paper pigments. The study explores the influence of temperature (50, 75and 100 °C), pulp density (5, 15 and 25 wt.-%), stirring speed (360 and 530 rpm) and process conditions(oxidative and reductive leaching) on the purification of synthetic rutile from a Malaysian ilmenite placer deposit. The study is aimed at determining the best combination of parameters that will produce a product of 95.5% synthetic rutile. A number of processes exist to obtain synthetic rutile from ilmenite ores. These are sulphate, alkaline and chloride based. However, the HCl treatment route was chosen for this study. This process exhibits fast kinetics, excellent impurities removal and the potential to regenerate the acid makes it sustainable and environmentally friendly. Samples of the ore screened to a 106 – 212 µm size fraction were treated with 700 mL of 18% (5.5 M) HCl. Leaching was conducted in 1 L reactor vessels with one suited for atmospheric pressure and the other for highpressure operations for a duration of 4 hours each. It was concluded that temperature was the main parameter influencing the level of purification for the synthetic rutile obtained. The pulp density was found to influence the amount of titanium and iron released in the leachate solution. However the objective of purifying the ilmenite ore to 95.5% synthetic rutile was not achieved. The highest purity achieved was 77 % with the process conditions of 100 °C, 15 wt.-% and 360 rpm. SEM analysis showed that the temperature and pulp density were intrinsically linked to the formation of a product layer around the ilmenite grains during the HCl treatment. Despite being effectively observed through SEM, this and other available data could not be conclusively used to validate a suitable kinetic model for the HCl treatment. The data did however show that the HCl purification ofthe synthetic rutile occurred in two phases. In the first phase, governed by chemical reactions, theacid permeates the particles facilitated by porosity and fractures of the grain and dissolves both ironand titanium. When a certain amount of titanium accumulates in the leachate solution it precipitatesand forms a layer around the grains. From this point on, a second phase begins in which kinetics are now governed by diffusion of iron through this layer which prevents any further penetration of acid into the grains. [less ▲]

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See detailCEReS Deliverable 4.2: Char PLS Treatment Unit Options
Arinanda, Muhammad ULiege; Gaydardzhiev, Stoyan ULiege

Report (2018)

Work Package 4 Char Leaching aims to demonstrate the feasibility for utilisation of the acidic leachates (biolixiviant) generated from coal wastes bioleaching (Work Package 3) as leaching agent for ... [more ▼]

Work Package 4 Char Leaching aims to demonstrate the feasibility for utilisation of the acidic leachates (biolixiviant) generated from coal wastes bioleaching (Work Package 3) as leaching agent for extraction of the base and high-value metals contained in the char originating from the pyrolysis of PCB’s (Work Package 2). After metals being leached from the char and accumulate in pregnant leach solution (PLS), the next task is to extract metal(s) of interest and recover it to obtain a high-purity product. Different from mineral ores, char (or pyrolyzed PCBs) contains various metals and elements, oftentimes in high grades. Most of the time, the leaching of the char is non-selective, meaning that other than metals of interest, the un-desired ones should also be dissolved at high concentration. This is proven to be problematic for recovery stage, thus highlight the importance of extraction stage as intermediate between leaching and recovery. The solvent extraction stage consists of two steps; extraction step to transfer metal ions from solution (aqueous) to extractant (organic), and stripping step to transfer metal ions back from organic to aqueous. Concentrated metal ions in the aqueous phase are then transferred to recovery stage to produce metal product with high purity. This report will subsequently present the result on investigation of solvent extraction to produce concentrated electrolyte solution, followed by the result on recovery stage by electrowinning to produce metal product. [less ▲]

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See detailCEReS Deliverable 4.1: Char Leaching Reactor Type
Arinanda, Muhammad ULiege; Gaydardzhiev, Stoyan ULiege

Report (2018)

Work Package 4 Char Leaching aims to demonstrate the feasibility for utilisation of the acidic leachates (biolixiviant) generated from coal wastes bioleaching (Work Package 3) as leaching agent for ... [more ▼]

Work Package 4 Char Leaching aims to demonstrate the feasibility for utilisation of the acidic leachates (biolixiviant) generated from coal wastes bioleaching (Work Package 3) as leaching agent for extraction of the base and high-value metals contained in the char originating from the pyrolysis of PCB’s (Work Package 2). The challenge of this Work Package is to find or design the suitable reactor for treating such material, which is unique compared to conventional materials treated in (bio)hydrometallurgy reactors, e.g. mineral ores, PCBs, etc. Stirred-tank reactor (STR) is the most commonly employed since the early days of biohydrometallurgy campaigns, ranging from lab-scale to industries, treating mineral ores to electronic wastes and residues. The main advantage of this type of reactor is the achievement of the desired levels of mass transfer, mixing, and suspension, in which STR outperforms other types of reactor. Due to that, STR has been given priority during Work Package 4 of CEReS project. Despite the advantages, STR faces the problem of char’s special physical characteristics. The disintegration of fibres followed by their suspension inside reactor needs a careful hydrodynamic design to maintain sustained mixing and mass transfer. Moreover, the high shear stress of impeller rotation may harm the presence of biofilm, risking the elimination of microorganisms from the biolixiviant. As an alternative, leaching performance on rotary-drum reactor (RDR) has also been studied in this work package. [less ▲]

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See detailProcess Oriented Characterization in Bioleaching Co-Cu Minerals
Nkulu, Guy; Gaydardzhiev, Stoyan ULiege

in DONATI, Edgardo (Ed.) HEAVY METALS IN THE ENVIRONMENT - Microorganisms and Bioremediation (2018)

This chapter presents the results from mesophilic bioleaching of high purity carrollite interpreted in view of the various interaction patterns between the microorganisms and the mineral substrate. The ... [more ▼]

This chapter presents the results from mesophilic bioleaching of high purity carrollite interpreted in view of the various interaction patterns between the microorganisms and the mineral substrate. The results outline the role which bacteria play in bringing cobalt and copper in solution. During the early bioleach stages, up to day 10, a pronounced attachment of the microorganisms on the mineral surface takes place which facilitates leaching reactions. SEM observations show evidence of contact bacteria-substrate which provokes release of ferrous ions in solution and formation of biofilm, the ferrous ions being subsequently oxidized by the “planktonic” bacteria. Two types of “fixed” bacteria are investigated: transiently-bound (reversibly detachable) and strongly-bound. The results suggest that when the mineral is in intimate contact with bacteria (“fixed” case) an enhanced oxidation takes place, in contrast to when bacteria are met in solution only (“planktonic” case). [less ▲]

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See detailElectro dynamic fragmentation of printed wiring boards as a preparation tool for their recycling
Martino, Rémi; Iseli, Cedric; Gaydardzhiev, Stoyan ULiege et al

in Minerals Engineering (2017), 107

The use of Electro Dynamic Fragmentation (EDF) enables selective fragmentation of materials through generating electrical discharges as a means of fracturing. Liberated materials can be thus processed ... [more ▼]

The use of Electro Dynamic Fragmentation (EDF) enables selective fragmentation of materials through generating electrical discharges as a means of fracturing. Liberated materials can be thus processed downstream in a more efficient way especially when value-added End-of-Life (EoL) electronic equipment is recycled. The aim of this study was to assess the benefits of the EDF technology towards processing of EoL printed wiring boards (PWBs) in view their recyclability. Printed wiring boards were comminuted using EDF at three different settings and with a hammer mill for comparative experiment. The products coming out were characterized by optical microscopy, SEM and liberation oriented leaching. Subsamples from the various EDF stages were inspected to investigate the progress of cracks and degree of copper layers exposure. The different energy levels used during the EDF processing have resulted in different degrees of PWBs damages, starting from components removal to entire structure perturbation and size reduction. EDF has resulted in generation of a lesser amount of fines, however the optimal approach in view energy efficient post-processing of the studied PWBs was the combination between single-stage EDF for components removal only with subsequent shredding of the depopulated boards. [less ▲]

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See detailCharacteristics of EoL Printed Wiring Boards processed by ElectroDynamic Fragmentation
Martino, Rémi ULiege; Iseli, Cedric; Gaydardzhiev, Stoyan ULiege et al

in Chemie Ingenieur Technik (2017), 89(1-2), 1-10

The ElectroDynamic Fragmentation (EDF) is an innovative technique which enables selective fragmentation of material. Its inherent selective breakage principles enable liberation while avoiding fine ... [more ▼]

The ElectroDynamic Fragmentation (EDF) is an innovative technique which enables selective fragmentation of material. Its inherent selective breakage principles enable liberation while avoiding fine grinding. In this study, the specific effects of the EDF on End-of-Life Printed Wiring Boards have been assessed. A novel methodology for their EDF processing has been developed and compared with hammer mill shredding. Various energy inputs and treatment stages have resulted in fragmentation degrees ranging from removal of components to structure delamination and subsequent size reduction. [less ▲]

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See detailElektrodynamische Fragmentierung von Elektroschrott
Iseli, Cédric; Streicher-Porte, Martin; Martino, Rémi ULiege et al

Poster (2016, November 11)

Untersuchungen dazu werden in diesem Bericht am Beispiel von WEEE und speziell an Leiter-platten aufgezeigt. Die Versuche zeigen, dass EDF für verschiedenste Arten von Elektroschrott eingesetzt werden ... [more ▼]

Untersuchungen dazu werden in diesem Bericht am Beispiel von WEEE und speziell an Leiter-platten aufgezeigt. Die Versuche zeigen, dass EDF für verschiedenste Arten von Elektroschrott eingesetzt werden kann. Verschweisste Kompaktgeräte können zum Beispiel so weit geöffnet werden, dass die ge-wünschte Komponente freigelegt und entfernt werden kann. Leiterplatten haben die Eigenschaft, dass bei kontinuierlich steigendem Energieeintrag zuerst die aufgebrachten Komponenten abgetrennt werden, bevor die Cu-Bahnen freigelegt werden. Bei noch höherem Energieeintrag wird die Leiterplatte schlussendlich zerkleinert und vollständig zer-stört. Durch diese Entfrachtung der Leiterplatte kann ein metallreiches Konzentrat hergestellt werden. [less ▲]

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See detailMalachite and heterogenite behavior during the locked-cycle recycling of process water in flotation of copper-cobalt oxide ores
Shengo, Michel; Gaydardzhiev, Stoyan ULiege; Kalenga, Pierre

in International Journal of Mineral Processing (2016), 157

The behavior of malachite and heterogenite was investigated during the process water recycling in flotation of copper-cobalt oxide ores from the deposit of Luiswishi located in Haut-Katanga province (DRC ... [more ▼]

The behavior of malachite and heterogenite was investigated during the process water recycling in flotation of copper-cobalt oxide ores from the deposit of Luiswishi located in Haut-Katanga province (DRC). A synthetic mill wastewater (SMWW) was utilized as feed water alone and in mixture with water recovered from the flotation tails in view to achieve at the laboratory scale the locked-cycle recycling of the industrial mill wastewater (IMWW). To simulate the chemical species presence in the pulp and their effects on the flotation of malachite and heterogenite, calcium, magnesium and bicarbonate ions were added to the feed water and the recoveries of copper and cobalt followed during the roughing flotation stage. The concentrate XRD and SEM analysis together with the floated minerals microanalyses by EDX spectroscopy, leaching tests of mono-minerals followed by the Pourbaix diagrams construction and DRIFT spectroscopy analyses, have enabled identifying changes in the surface properties of malachite and heterogenite interfering on the recovery of copper (40 %) and cobalt (58 %) with a significant drop in their concentrate grades (7.3 % Cu and 2.7 % Co). The deterioration of the concentrate characteristics results also from the gangue minerals entrainment. A better description of the valuable minerals behaviour in the SMWW presence could enable designing strategies in view enhancing their floatability during the locked-cycle recycling of water. [less ▲]

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See detailThe role of bacteria and the addition of pyrite during leaching of Co(III) from heterogenite
Zeka, Leon; Gaydardzhiev, Stoyan ULiege; Frenay, Jean ULiege et al

in Proceedings of the XXVIII International Mineral Processing Congress (IMPC 2016) (2016, September 11)

Reductive leaching of cobalt (III) from a heterogenite bearing ore has been performed. Pyrite was added to the system and simultaneously bioleached in order to provide ferrous iron as reducing agent ... [more ▼]

Reductive leaching of cobalt (III) from a heterogenite bearing ore has been performed. Pyrite was added to the system and simultaneously bioleached in order to provide ferrous iron as reducing agent. Within such arrangement the iron ions are continuously re-circulated inside a Fe3+/ Fe2+ loop. As a result Co(III) is solubilized in the presence of Fe2+ ions in concentrations well below the stoichiometric requirement. The ore has been initially subjected to acid pre-leaching in order to guarantee that the available Co (II) has been entirely removed. Two technological parameters have been studied to show influence on the degree of cobalt leaching: concentration of ferric iron in the inoculum and the presence of bacteria. The bacterial role could be mainly viewed in supplying ferric ions in the system which chemically react with the pyrite to generate ferrous ions used as Co(III) reducing agent. Co(III) dissolution has been less efficient when the concentration of total iron in the system was low, but also when microorganisms were absent. SEM observations on leached heterogenite have evidenced bacterial attack on the mineral; however the precise role of bacterial presence on cobalt (III) leaching is still to be elucidated. [less ▲]

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See detailGeometallurgical Modelling of Low-Grade Itabirite Iron Ores from the Iron Quadrangle, Brazil
Martino, Rémi ULiege; Correa de Araujo, Armando; Gotelip Barbosa, Marcela et al

in Proceedings of the XXVIII International Mineral Processing Congress (IMPC 2016) (2016, September 11)

The Iron Quadrangle district is a world-class iron ore mining district in the region of Belo Horizonte, capital of Minas Gerais state, in Brazil. Many mining companies have been mining high-grade hematite ... [more ▼]

The Iron Quadrangle district is a world-class iron ore mining district in the region of Belo Horizonte, capital of Minas Gerais state, in Brazil. Many mining companies have been mining high-grade hematite ores for decades throughout the region. The mines reserves often include itabirite ores which are available in high volumes, but have lower iron grades than hematite ores and require elaborated mineral processing to meet the requirements of downstream steelmaking. Itabirite ores have acquired importance, with the depletion of high-grade hematite reserves due to their intensive mining. The objective of this paper is to propose a geometallurgical model for the processing of itabirite ores from an Iron Quadrangle deposit, which will allow predicting the behaviour of ores throughout the deposit, according to their local variations. An initial step consists in characterizing representative samples of the different ores to acquire mineralogical and textural data. Then, itabirite ores of known characteristics are processed with different techniques, in order to extract the trends and key parameters upon which the geometallurgical model is developed. At first, the model takes into account the particle size distribution and its shift during mining and screening, as well as the chemistry and mineralogy of the material. Then, using the previously identified key parameters such as iron recovery, the model predicts the composition of the processing products. Finally, this data is used to model the mineralogy and mass recovery of the products. The geometallurgical model is of great importance, as it is able to model the processing of any sampled ore throughout the deposit. The incorporation of the results in a mining block model will assist mine planning and opens new opportunities for an optimized mining schedule. [less ▲]

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See detailProcess oriented characterisation of oolitic iron concentrate during dephosphorisation by roasting and leaching
Ionkov, Krassimir; Gomes, Otavio; Neumann, Reiner et al

in Proceedings of the XXVIII International Mineral Processing Congress (IMPC 2016) (2016, September)

Phosphorus in iron ores is considered as a deleterious component to iron making reflecting in cold shortness of the produced steel. The present study investigates the phosphorus migration pattern ... [more ▼]

Phosphorus in iron ores is considered as a deleterious component to iron making reflecting in cold shortness of the produced steel. The present study investigates the phosphorus migration pattern resulting from thermal treatment of an oolitic-type iron concentrate with and without additives. To this end focused mineralogical and microscopic observations were performed. The results have shown that roasting with alkaline additive drives phosphorus outside the hematite hosting mineral, however it remains evenly distributed inside the volume of the oolites. It penetrates inside the newly formed cementing phases of Al-Na-Si-Fe-type and also fills the interstices between the crystals. Other than phosphorus, aluminum, calcium and iron tend also to migrate towards the amorphous-type cementing phase. Finally, the possibilities for P removal by means of magnetic separation and acid leaching of the roasted concentrate were evaluated. The obtained final product presents a standard iron concentrate suitable for steelmaking with its phosphorous being dropped from 0.71% to 0.05% and iron grade of a nearly 66% being reached. [less ▲]

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