Leaching Of Ore Research Articles

Electrochemical reduction and recovery of trace gold(I) from environmentally friendly thiosulfate leaching solutions using carbon electrodes

Efficient recovery of Au(S2O3)23− at low concentrations is a key challenge for the development of environmentally friendly, cyanide-free thiosulfate leaching methods in industry. In the study, carbon materials including activated carbon (AC), graphite, and graphene were used as electrodes for electrochemical reduction and recovery (electro reduction-recovery) of trace gold(I) from thiosulfate leaching solutions (Au(S2O3)23−). The results demonstrated that Au(S2O3)23− could be efficiently recovered in the form of Au0 with nearly 100 % recovery from both simulated and actual gold ore leaching solutions, significantly simplifying traditional recovery and reduction processes. Even in the presence of impurities such as cations and S2O32−, recovery remained high, around 90 %. Among the parameters studied, applied voltage was the most critical for optimizing recovery, as it enhanced ion migration and significantly improved gold reduction. The study investigated the relationship between the intrinsic properties of carbon materials and their electrochemical reduction and recovery capabilities. Rich porosity of carbon materials promoted interactions with Au(S2O3)23−, enhancing the electric double layer capacity, while π–π∗ satellite transitions played a dominant role in the charge transfer, thereby improving the reduction rate. This research offers new insights of the mechanisms behind the recovery of trace Au(S2O3)23− from thiosulfate leaching solutions through carbon electrodes.

Assessment of Metal Enrichment in the Koma Bangou (Niger) Gold Panning Area Soils and Tailings

Artisanal and small-scale gold mining at Koma Bangou (Niger) has been going on since the Sahelian 1984’s drought, with introduction of ore leaching in the year 2009. The use of chemicals in the ore processing results in metal enrichment and pollution at the cyanidation sites. The aim of this work is to assess the metal enrichment of soils and tailings at Koma Bangou. Geochemical data acquired with portable XRF analyzer corrected with ICP-MS data, were used to assess the enrichment level of As, Cr, Cu, Mn, Pb and Zn in the soils and tailings samples using the enrichment factor and soil-geochemical baseline data for the Koma Bangou soils. The metallic enrichment generated by the ore processing was identified in the tailings (cyanidation and acidification waste) and the soils from the cyanidation areas. The perimeter soils (soils outside cyanidation sites) show no metal enrichment. Pb and As are extremely high to very high enriched in the cyanidation waste, with an average enrichment factor value of 44.96 and 34.96 respectively. Zn, Cu, Cr are extremely high to significant enriched in the acidification waste, with an average enrichment factor value of 793.35, 29.46 and 5.22 respectively. Mn enrichment is insignificant in all of the samples with an average enrichment factor value of 1.00 in the perimeter soils. The gold ore leaching activities generate metallic pollution of the soil, water and vegetation around the cyanidation sites.

Iron Separation from Iron-Rich Manganese Ore Leachate: Comprehensive Optimization of Operating Parameters and Economic Viability

In the current electrolytic manganese industry, iron separation and reuse from iron-rich manganese ore leachate (IRMOL) has become one of the most pressing challenges. This study aimed to investigate the optimal conditions for iron separation from IRMOL and to assess the economic and practical advantages of iron separation or removal in industrial manufacturing. To identify more cost-effective and technologically advanced production circumstances, we examined five key elements that weaken Fe(OH)3 colloidal production conditions in enterprises: reaction temperature, pH, crystal species, aging, and reaction time. The screening results showed that when the conditions were optimized, the efficiency of reducing manganese loss decreased from 6.15% to 4.69%. Additionally, the generation of iron-rich electrolytic manganese residue (IREMR) was decreased by 44.32%, and the filtration velocity of IREMR increased from 0.0030 to 0.0220 mL/(s·cm2) compared to the production conditions before optimization at the enterprise. Through multiphase equilibria modeling with Visual MINTEQ, we have determined that raising the temperature and pH levels increases the expenses associated with chemicals and energy usage and results in an elevation of Fe(OH)2+ concentration. This can lead to the creation of Fe(OH)3 colloidal, causing a high water content in IREMR, inefficient filtration, and significant loss of manganese. This strategy is highly significant for the production of electrolytic manganese and the reduction of electrolytic manganese residue.

Bromic acid-thiourea synergistic leaching of sulfide gold ore

Abstract Bromate–thiourea coordinated leaching of gold sulfide ore for gold sulfide ore as leaching object. The effects of leaching reagent, stirring speed, and leaching time on gold leaching were investigated in this article. The results showed that the optimum leaching conditions were potassium bromate 0.1 M, thiourea 0.6 g·L−1, hydrochloric acid 0.2 M, agitation speed 250 rpm, ratio of liquid to solid 4, and leaching time 10 min. Under these conditions, high efficiency and rapid leaching of gold can be achieved, and reagent consumption is reduced. The research results have theoretical and practical significance for expanding new green gold extraction technology.

Environmentally sound geotechnologies for leaching metals from polymetallic ore processing wastes and wastewater

Global challenges (increased consumption of georesources, climatic changes, limited reserves) increase the relevance of the problems of growing waste accumulation and environmentally-sound modernization of mineral extraction. In this regard, the existing approaches to the design of geotechnologies for metal mining need to be improved based on a concept of so-called circulation waste management and ecologization of technological processes. The paper is devoted to the issue of formation of conceptual bases and directions of ecologization of geotechnologies at leaching metals from polymetallic ore processing wastes and wastewater. The study presents recommendations for improving in-situ leaching of ores in blocks, allowing to determine the optimal conditions for increasing the completeness of subsoil use and reducing environmental damage. It was revealed that at metal extraction with solution circulation through brine chambers the content of Na, Cl, SO4 and Ca ions in dialysate was low, while without circulation through brine, it significantly exceeded corresponding MPCs. This proves the fundamental feasibility of controlling natural leaching processes by enhancing the oxidizing potential of natural solvents through the addition of industrial oxidizing agents. It was found that increasing the duration of agitation leaching (both with and without mechanoactivation) leads to a uniform expansion of the local maximums of Pb yield from the pulp when the minimum NaCl concentration decreases from 11–12 to 7% at H2SO4 concentration of 0.6%. One of key results of the study is justifying the expansion of the use of disintegrators to realize targeted activation of tailings. The practical significance of the obtained results lies in the proved feasibility of optimizing the flow sheet of electrochemical extraction of metals from wastewater on the basis of the obtained regularities of the use of brine circulation through brine chambers. In addition, the totality of the obtained results of using a disintegrator for reextraction of lead from geomaterials will allow developing a methodology for calculating the parameters of mechanoactivation action to increase the degree of metal recovery from the tailings of North Ossetia-Alania’s (Zgidskoe, Sadonskoe, Arkhonskoe deposits) polymetallic ores beneficiation. The most promising way for further research is to substantiate methods of using underground space for complete removal of wastes (wastewater and tailings) after their multistage treatment.

HPAL of a lateritic nickel ore: An investigation on the relationship between nickel and cobalt extraction and acid consumption

Nickel and cobalt raw materials have become essential in industries like batteries such as robotics, and drones, which are considered as future technologies due to their expanding applications and diversity. Research towards the development of environmentally friendly and relatively low-cost alternative methods for extracting nickel, particularly from low-grade deposits, is becoming increasingly crucial. Laterite ores processing is plagued by high reagent consumption and scale formation. This study focused on investigating the relationship between Ni and Co extraction and acid consumption in the high-pressure acid leaching of lateritic ore, as well as the characterization of leach residue. Analysis has shown that the lateritic ore contains 1.05 % Ni, 0.05 % Co and 21.94 % Fe. In the acid leaching tests based upon a Box-Behnken Design, the initial acid concentration and leach time have a beneficial effect on the Ni extraction (70–94 %). Cobalt extractions ranged between 93 % and 96 %. To facilitate Fe dissolution and increase Ni extraction, cuprous ions were added into the leach solution. Moderate level copper addition (0.025 M) resulted in a significant improvement in Ni extraction, whereas high levels of cuprous addition (0.050 M) did not have further benefit. It has been noted that adding cuprous ions significantly reduces the amount of scale that forms in the autoclave. The lowest Ni extraction was obtained under two different test conditions that did not include copper ions. Increased acid addition was correlated with the increase in Ni leaching and decreased Fe content in residue. There will exist an optimal situation where the acid addition is enough to enhance Ni dissolution and the Eh condition, leading to minimal dissolved Fe.

Particle Shape-Based Evaluation of the Leaching of Sphalerite Ore in Dilute Acid Solutions

In this study, the effects of changes in particle shapes on dissolution efficiencies in zinc (Zn) recovery from a lead-zinc (Pb-Zn) ore by acid leaching method were investigated. In the experiments with nitric acid (HNO3), sulfuric acid (H2SO4), and hydrochloric acid (HCl), particle size (75-106-150 µm), solids ratio (5-10-15-20-25%), leaching time (30-60-120-180-240 min), acid dosage (0.25-0.5-1-2-5 M) and pulp temperature (30-40-50-60-70 oC) parameters were analyzed. Optimum results were obtained under the conditions of 75 µm particle size, 15% solids ratio, 120 min leaching time, 0.5 M acid dosage, and 50°C pulp temperature for H2SO4; 106 µm particle size, 25% solids ratio, 60 min leaching time, 0.5 M acid dosage, and 70°C pulp temperature for HCl; 75 µm particle size, 20% solids ratio, 60 min leaching time, 1 M acid dosage, and 50°C pulp temperature for HNO3. As a consequence of the tests performed under these optimized conditions, 97.32%, 96.38% and 96.06% Zn dissolution efficiencies were obtained. Within the context of particle shape factor research, microscope images of the leaching residues were obtained from the experiments in which the pulp temperature, acid dosage, and leaching time parameters were examined. The samples obtained from the experiments with all three acids were compared with the ore samples, and the impacts of changes in circularity, roundness, and solidity values on dissolution efficiencies were interpreted.

A strategy for treatment of low-grade ore: Efficient separation and purification of iron

The gradual depletion of mineral resources has led to the emergence of a new engineering challenge in the field of mineral processing: the effective treatment of low-grade ores. In this study, the low-grade titanium ore leaching solution was employed as the raw material. The extraction ability of a series of hydroxyl extractants for the most common metal iron in minerals was investigated. As a result, a new high-quality processing system for low-grade ore with branched-chain octanol as the core component was constructed. In the treatment of mineral leaching solution, branched-chain octanol has high selectivity and large capacity (111.7 g/L) for iron. It was capable of efficiently removing a significant quantity of iron ions in low-grade ores that were not anticipated to be present. By employing quantum chemical (QC) methodologies, the mechanism for the high selectivity of branched-chain octanol for Fe(Ⅲ) has been elucidated by analyzing the frontier molecular orbital (FMO) energy of acid salts of common metals in minerals. Combined with spectral analysis and slope method, the structure of the extracted complex was confirmed to be [n-R8-OH]2·H·FeCl4. On the basis of system optimization, a three-stage countercurrent extraction and three-stage countercurrent stripping was employed to remove all the Fe(Ⅲ) in the mineral leaching solution. And after detecting, the purity of the obtained Fe(III) solution was greater than 99.5 %. In the treatment of low-grade minerals, especially those containing key metals, the branched-chain octanol extraction system demonstrates high selectivity and reliability, which is a effective means to improve the quality of mineral leaching solution.

Sulfuric Acid Leaching of Carbonatite ore with High Calcite Content in Lugiin Gol under Ambient Condition

AbstractCarbonatite bearing rare earth elements are rich sources of rare earth elements and play a critical role in the global supply chain. While carbonatite deposits are less accessible compared to ion adsorption clays, their mineral composition makes them essential for rare earth element extraction. Extraction of rare earth elements from carbonatite ore involves acid leaching, a process that we aim to explore in this study using the carbonatite ore from Lugiin gol. Characterization of the raw material and solid residue post‐leaching was conducted using X‐ray diffractometry, inductively coupled plasma optical emission spectroscopy, and a zeta potential analyzer. These analytical techniques were utilized for kinetic modeling, assessing the influencing factors of leaching, and determining metal recovery in the pregnant solution. The results of the study highlight the significant role of surface charge formation on target particles during milling in the acidic leaching process. This finding shed light on the importance of understanding the surface properties of the particles in the extraction of rare earth elements from carbonatite ores. The surface of particles in the supernatant of rare earth elements’ ore was negatively charged, with the median zeta potential of the 0.025 mm fraction being at its minimum of −60.6 mV.

Kinetics of regeneration of oxidative Cu(II) and Fe(III) species in aerated acid chloride leaching solutions at 75 °C

In the leaching of copper sulfide ores or refractory gold ores in chloride solutions, the regeneration of oxidative agents such as Cu (II) and Fe (III) is a key aspect for a sustainable process over time. This regeneration is carried out from the oxidation of Cu (I) and Fe (II) with O2, which helps to maintain a conveniently high oxidative potential in solution and a high leaching efficiency. In this context, Cu (I) and Fe (II) oxidation are affected by the accumulation of Cu or Fe species resulting from sulfide dissolution during the process. Therefore, a good understanding of the interaction mechanism of O2 with Cu (I), Cu (II), Fe (II), and Fe (III) species is necessary to describe the oxidation kinetics in this complex environment. The present work reports a study of the Cu (I) and Fe (II) oxidation at 75 °C in solutions containing 4.0 M NaCl and 0.1 M HCl. The solutions used in the experiments contained different initial concentrations of Cu (I), Cu (II), Fe (II), and Fe (III) with values in the range of 0.0001 – 0.1 M. Experiments were conducted in a thermostatized reactor containing 0.5 L solution agitated with a magnetic stirrer at 450 rpm, while oxygenated by air bubbling at 3.5 L/min. The evolution of the concentration of Cu (I), Cu (II), Fe (II), and Fe (III) during oxidation was determined by an electrochemical method, which was mainly based on Eh measurements of solution over time. A reaction mechanism was proposed for the oxidation of Cu (I) and Fe (II) with O2 in the presence of Cu and Fe species, which described very well the results obtained in the oxidation experiments under various conditions. Based on the proposed mechanism, a kinetic model was developed that could predict the concentration of Fe (II), Fe (III), Cu (I), Cu (II), O2, HO2–, H2O2, OH– and H+ in acid aerated chloride solutions satisfactorily. These proved to be a valuable tool to approach the modeling of chloride-leaching reactors.

Electrokinetic-enhanced sulfuric acid leaching of uranium from sandstone uranium ores

Solute transport in conventional acid leaching of sandstone uranium ores is limited by diffusion and convection, resulting in extended leaching cycles. This study described an electrokinetic-enhanced method for leaching sandstone uranium ore with sulfuric acid and was intended to investigate the impacts of potential gradients on leaching efficiency. Electrokinetic horizontal column leaching experiments were conducted on sandstone uranium ore. After 20 h of leaching, the uranium leaching efficiencies were 54.90 %, 56.36 %, 68.33 %, and 82.04 % for potential gradients of 0, 0.5, 1.0, and 2.0 V/cm, respectively. The uranium leaching efficiency of sandstone at a 2.0 V/cm potential gradient was 27.14 % greater than that at a 0 V/cm potential gradient, and the leaching time was decreased by approximately 40 % at the same uranium leaching efficiency. Analyses of the chemical fraction of uranium, XRD and SEM-EDS showed that the applied potential gradient facilitated solute transport during leaching, thus accelerating the leaching efficiency of adsorbed uranium, tetravalent uranium, and uranium encapsulated in lattices of silicates and primary and secondary minerals in sandstone uranium ores. Therefore, electrokinetic action is excellent for enhancing the effectiveness of sulfuric acid leaching of sandstone uranium ores and has broad application prospects.

Efficient Acid Leaching of Low Carbonate Copper Oxide Ore: A Focus on Impurity Minimization

Efficient Acid Leaching of Low Carbonate Copper Oxide Ore: A Focus on Impurity Minimization

The Effect of Various Parameters in the Sulfuric Acid Leaching of Low Grade Zinc Oxide Ore of Niğde-Türkiye

The aim of this study was to investigate the main parameters affecting the leaching of low grade zinc oxide ores with sulfuric acid. The influence of leaching time (5 to 480 minutes), sulfuric acid concentration (25 to 125 g/L), leaching temperature (25 to 90 °C), particle size (-104 µm, -82 µm, -60 µm, -49 µm) and solid/liquid ratio (1/10, 1/7.5, 1/5, 1/4) was investigated. The effects of these process parameters were studied with to achieve maximum zinc extraction with minimum iron extraction and acid consumption. The optimum parameters for sulfuric acid leaching of zinc ore were determined to be 60 min leaching time, 75 g/L sulfuric acid concentration, 80 oC leaching temperature, 1/10 solid/liquid ratio and -60 µm particle size. Under these optimum conditions, Zn extraction (%), Fe extraction (%) and acid consumption (ton H2SO4/ dissolved ton Zn) were obtained 88.68%, 25.83% and 5.47 ton H2SO4/ dissolved ton Zn respectively.

Study on the role of microbial metabolites in in-situ noncontact bioleaching of ion-adsorption rare earth ore

Ion adsorption rare earth ore nearly satisfy global market demand for heavy rare earth elements (HREEs). Bio-leaching has important potential for the clean and efficient extraction of ion-adsorption rare earth ore. However, the complexities of in-situ mining restrict the use of contact/direct bio-leaching, and non-contact/indirect bio-leaching would be the best choice. This study explore the potential of fermentation broths prepared by Yarrowia lipolytica (ATCC 30162) for the bio-leaching of ion-adsorption rare earth ore, and three typical metabolites (potassium citrate (K3Cit), sodium citrate (Na3Cit) and ammonium citrate ((NH4)3Cit) of Yarrowia lipolytica were further evaluated in simulated bioleaching (non-contact bioleaching) of ion-adsorption rare earth ore, including leaching behavior, seepage rule and rare earth elements (REEs) morphological transformation. The column leaching experiments shown that direct leaching of REEs using fermentation broths results in incomplete leaching of REEs due to the influence of impurities. Using the purified and prepared metabolites as lixiviant, REEs can be effectively extracted (leaching efficiency >90%) at cation concentration was only 10 % of the commonly used ammonium sulfate concentration (45 mM). Cation type had less effect on leaching efficiency. During the ion-adsorption rare earth ore leaching process, rare earth ions form a variety of complex chelates with citrate, thus transferring rare earth elements from the mineral surface to the leachate. Experimental results showed that pH and concentration together determined the type and form of rare earth chelates, which in turn affect the leaching behavior of REEs and solution seepage rule. This study helps to provide a theoretical basis for the regulation and enhancement of ion-adsorption rare earth ore non-contact bioleaching process.

Untargeted metabolomics reveals the mechanism for leaching rare earth elements from ion-adsorption rare earth ores using a composite lixiviant

Rare earth elements (REEs) are an important strategic scarce resource, and how to mine and utilise them efficiently and greenly is a difficult problem. In this study, to reduce the use of chemical reagents in the leaching process, Bacillus thuringiensis fermentation broth and magnesium acetate were used as composite lixiviants to leach REEs from ionic rare earth ores via biochemical synergy. The effectiveness of composite lixiviant for leaching REEs was studied, and the optimum leaching conditions were determined. In addition, untargeted metabolomics was used to explore metabolite differences and metabolic pathway profiles before and after leaching with the composite lixiviant. The interaction between the composite lixiviant and the rare earth minerals was also investigated by combining various characterisation tools. The results showed that the leaching rate was 96.3 % when the concentration of magnesium acetate in the composite lixiviant was 0.3 mol/L, the pH was 4, and the liquid–solid ratio was 2:1. Metabolomics analysis showed that lipids and lipid-like molecules, benzenoids, and organic acids, and derivatives contained in the fermentation broth of the complex leach play an important role in the leaching process. This study provides a new composite lixiviant for leaching ionic REEs, which can reduce the dosage of chemical reagents, provide a reference for the biochemical synergistic leaching of ionic rare earth ores, and help guide environmentally friendly and efficient leaching of ionic rare earth ores in the future.

Copper sulfide precipitation from alkaline monosodium glutamate solutions

Recent studies of metal leaching using monosodium glutamate have shown promising results of this being an alternative to conventional leaching reagents. However, limited information is available covering the treatment of leaching solutions and the final recovery of metals. In this regard, this article presents an experimental study on the precipitation of copper from glutamate solutions using sodium hydrosulfide (NaHS), as a simple and efficient route for the processing of leaching solutions from this new system. Synthetic pregnant leach solutions (PLS) with varying copper total concentrations [CuT] and glutamate concentrations were used. The effects of [CuT], [CuT]:[NaHS] molar ratio and glutamate concentration on the particle size distribution and copper recovery were investigated. The results revealed that higher [CuT] led to smaller particle sizes, with the P90 decreasing from 106 µm to 60.7 µm and 73.2 µm for Cu concentrations of 1 g/L, 2.5 g/L, and 5 g/L, respectively. The [CuT]:[NaHS] molar ratio reduced the P90 particle size, from 60.7 µm to 56.4 µm and 7.44 µm as the molar ratio increased from 1:0.8 to 1:1 and 1:1.2, respectively. Copper recovery from glutamate solutions increased with higher molar ratios, achieving values of 70.95 %, 88.24 %, and 99.55 % for molar ratios of 1:0.8, 1:1, and 1:1.2, respectively, agreeing with copper recovery values of other chemical systems. The glutamate concentration had minimal impact on particle size but affected copper recovery, with a decrease from 88.24 % to 85.83 % when increasing the glutamate concentration from 0.5 M to 1 M. X-ray diffraction (XRD) analysis confirmed the presence of pure covellite with hexagonal phase in the precipitates. These findings contribute to understanding copper precipitation dynamics from glutamate solutions using NaHS and have implications for optimizing copper recovery processes in the perspectives of the advent of alkaline leaching of copper ores.

Identification of processes in Cu-ore heap leaching using Cu isotopes and leachate chemistry at Tschudi mine, northern Namibia

Copper isotopic fractionation (in δ65Cu) and leachate characterization were studied in the context of heap leaching at the Tschudi copper mine in northern Namibia. The leached solution is of Mg-SO4 type with high Al and Fe concentrations. The source of Mg and Al in the leachate can be from the alteration of micas such as Mg-bearing muscovite confirmed by X-ray diffraction and scanning electron microscopy; however, the source of Mg cannot be determined with certainty. The principal secondary minerals identified in the leached ore are gypsum and jarosite. The value of pH in leachate is ∼1.21 and the concentration of dissolved Cu, occurring mostly as CuSO40 and Cu2+, is about 2 g/L. In comparison with unleached ore (avg. δ65Cu −1.47 ‰), leached ore exhibits lighter isotopic values (avg. δ65Cu −6.01 ‰) with apparent isotopic fractionation Δ65Culeached ore-unleached ore of about −4.54 ‰. In contrast, there is isotopic enrichment of leachate in heavier 65Cu isotope (leachate δ65Cu 0.34 ‰) with apparent isotopic fractionation Δ65Culeachate-unleached ore value of +1.81 ‰. These results are in good agreement with Cu isotopic fractionation and depletion in heavier 65Cu isotope reported for dissolution experiments in laboratory and groundwater linked to the porphyry copper ore deposits around the world. The leaching of heaps can be considered an analogy of upper part of gossans, but here the supergene enrichment zone is missing due to extremely low pH and oxidizing conditions.

Copper leaching from complex chalcopyrite-rich ores: Utilizing mechanical activation and wastewater-based sulfuric acid system

Complex chalcopyrite-rich ore is crucial in global copper resources, but is highly refractory in conventional sulfate leaching system. In this paper, we explore the leaching of complex chalcopyrite-rich ores employing a mechanically activated pretreatment combined with wastewater with high concentrations of chloride. The investigation delves into various parameters, including reaction temperature (60 to 90 °C), sulfuric acid concentration (0.005 to 2.0 M), chloride concentration (0 to 1.5 M), liquid/solid ratio (0 to 200), stirring speed (100 to 580 rpm), leaching time (0 to 4 h) and grinding time (0 to 7 h), to evaluate their impact on copper recovery from complex chalcopyrite-rich ores. Furthermore, a comprehensive kinetic analysis of copper leaching behavior was studied, encompassing specific surface area, amorphization degree, grain size, and microstrain. In the sulfuric acid system utilizing wastewater, the presence of mechanical activation and chloride content enhances copper leaching while mitigating the passivating effect of elemental sulfur. Notably, following a leaching period of 4 h at 80 °C, the copper leaching efficiency remarkably reached 89.46 %. In addition, kinetic analysis of copper leaching at temperatures ranging from 60 to 90 °C via a shrinking core model with R2 > 97 %, indicates that the leaching process of copper is primarily governed by solid product layer diffusion, with an activation energy of 54.32 kJ/mol. These findings highlight the efficacy of the proposed approach in optimizing copper recovery from complex chalcopyrite-rich ores, offering insights into the underlying mechanisms driving the leaching process.

Heap leaching of primary and complex copper ore with activation pre-oxidation

Heap leaching of primary and complex copper ore with activation pre-oxidation

Investigation of the effect of mechanical activation on nickel and cobalt extraction from laterite at atmospheric pressure by kinetics and leach residue analysis

ABSTRACT Nickel and cobalt extraction from laterite has been studied for years but has not been investigated enough by leach residue analysis. Also, the kinetic approach and leach residue analysis become important when mechanical activation improves nickel and cobalt extraction. Various kinetic assumptions were applied to understand the dissolution behaviour of Ni, Co, and Fe. The ore was activated mechanically in a planetary ball mill as a pre-treatment. The effects of liquid-to-solid ratio, acid ratio, leaching time, and temperature on the leaching of non-activated ore were studied to fix the parameters for the leaching of pre-treated ore. Leaching efficiencies of activated ore for 15 and 60 min exhibited better results at lower temperatures and shorter times than non-activated ore. Nickel extraction has 70% efficiency for 5 min leaching at 95°C in mechanically activated ore. Besides higher dissolution efficiency, apparent activation energy (Ea) decreased. Dissolution of metals from non-activated and activated ore was found to be mixed-controlled. Two different diffusion-controlled mechanisms that differ in the diffusion coefficient-time relationship were detected. An analysis of leach residue supported this finding.