Effect of pre-roasting on leaching of laterite

The effect of pre-roasting on leaching of the gamierite laterite ore, obtained from Yunnan province, China, was investigated in this study. The phase transformation of laterite minerals roasted at different temperatures was investigated with X-ray powder diffraction (XRD). The roasting experiment results show that there are two phase transformation processes of dehydroxylation of goethite and lizardite at roasting temperatures of 277 °C and 610 °C, respectively, which accord with the result of DTA–TG analysis. Pre-roasting of the laterite not only alters its mineralogical composition but also increases its porosity and surface area, thus making it more amenable to leaching. Compared to the leaching result of raw ore and ores roasted at different temperatures, it indicates that increasing roasting temperature up to 300 °C appears to provide the optimum nickel recovery and further heating appears to be detrimental to the nickel recovery.     

Pressure acid leaching of a Chinese laterite ore containing mainly maghemite and magnetite

The high pressure acid extraction of nickel and cobalt from a Chinese laterite containing mainly maghemite and magnetite was studied. X-ray diffraction (XRD) and scanning electron microscopy/X-ray energy dispersive spectroscopy (SEM/EDS) were employed to characterize the residues. The factors influencing the dissolution of maghemite and magnetite, nickel and cobalt extractions and iron precipitation were investigated. The results show that after 75 min at 270 °C with an acid/ore ratio of 0.55, maghemite and magnetite completely dissolved, liberating 98% Ni and 88% Co into the leach liquor. EDS analysis reveals that some nickel may be associated with the amorphous silica and/or basic ferric sulfate, resulting in a minor loss of nickel. The presence of a cobalt-containing phase in the residues, believed to be ringwoodite, is mainly responsible for the incomplete extraction of cobalt. Both maghemite and magnetite dissolved gradually with the increase in temperature from 200 to 270 °C. Maghemite dissolved more slowly than magnetite at 270 °C which also produced ferrous sulfate in the leach liquor and increased the total iron extraction. Increasing temperature and/or agitation accelerated the hydrolysis of ferric sulfate. The leaching of maghemite and magnetite corresponds to a dissolution-precipitation mechanism. In both high and low acidic environments, the precipitation of ferric sulfate proceeds through the initial formation of basic ferric sulfate and its conversion to hematite. The extent of conversion depends largely upon residual acidity and reaction time.     

Atmospheric acid leaching of nickel laterites review: Part I. Sulphuric acid technologies

This review examines the atmospheric leaching (AL) of nickel laterite ores with sulphuric acid, specifically the limonite, smectite (clay) and saprolite fractions. The kinetics and mechanism of leaching of the key minerals are reviewed together with methods for enhancing nickel recovery. Existing and developing AL processes for extracting nickel and cobalt from these ores are then considered with comparison to high pressure acid leaching (HPAL) technology. This review also provides an overview of the emerging hybrid HPAL/AL and heap leaching technologies.     

Intensification of sulphation and pressure acid leaching of nickel laterite by microwave radiation

The microwave is a clean and environmentally acceptable energy and various microwave-assisted metal extraction processes have been developed. The novel application of microwave irradiation for sulphation of the nickel laterite ore prior to pressure sulphuric acid leaching has been investigated. Under optimum conditions, about 92% of nickel can be extracted from the ore and above 90% of the iron precipitates as hematite with the residual acid content in the leachate lower than 31 g/L. The microwave sulphation proceeds rapidly and a relatively low leaching temperature and low mass ratio of sulphuric acid to ore can be used in the subsequent pressure leaching to achieve a satisfactory nickel extraction. This may potentially reduce the subsequent heavy capital and operation cost of the pressure acid leaching process.     

Study of extraction and purification of Ni, Co and Mn from spent battery material

In spent battery material, there are plenty of valuable metals, such as copper, nickel, cobalt, manganese. Recovery of valuable metals from spent battery material not only protects the environment but also improves the utilization of resources and decreases the cost of battery material. In this study, hydrochloric acid is used as lixivant with characteristics of faster leaching rate and being recycled easily. The optimal conditions are that hydrochloric acid concentration is 6 mol/L, reaction temperature is exactly 60 °C, liquid/solid ratio is 8:1, (H₂O₂)_mol/(MeS)_mol = 2, and the leaching time is 2 h, the results show that the dissolution yields of Ni, Co and Mn can be 95 wt.% at least. The basic purification concept of the leaching solution includes that copper is removed through replacement by iron powder followed by iron precipitation in goethite method. The results show that Cu and Fe can be removed 99 wt.% at the least. At the same time, the loss of Ni, Co and Mn is not beyond 2 wt.%, 3 wt.％ and 2 wt.%, respectively. This method makes the preparation of pure Ni_xCo_yMn_z ternary system precursor economical. The process seems to be able to claim base metals from waste in a reliable and feasible way.     

A novel recovery process of metal values from the cathode active materials of the lithium-ion secondary batteries

A novel process was conducted with experiments which separated and recovered metal values such as Co, Mn, Ni and Li from the cathode active materials of the lithium-ion secondary batteries. A leaching efficiency of more than 99% of Co, Mn, Ni and Li could be achieved with a 4 M hydrochloric acid solution, 80 °C leaching temperature, 1 hour leaching time and 0.02 gml^− 1 solid-to-liquid ratio. For the recovery process of the mixture, firstly the Mn in the leaching liquor was selectively reacted and nearly completed with a KMnO₄ reagent, the Mn was recovered as MnO₂ and manganese hydroxide. Secondly, the Ni in the leaching liquor was selectively extracted and nearly completed with dimethylglyoxime. Thirdly, the aqueous solution in addition to the 1 M sodium hydroxide solution to reach pH = 11 allowed the selective precipitation of the cobalt hydroxide. The remaining Li in the aqueous solution was readily recovered as Li₂CO₃ precipitated by the addition of a saturated Na₂CO₃ solution. The purity of the recovery powder of lithium, manganese, cobalt and nickel was 96.97, 98.23, 96.94 and 97.43 wt.%, respectively.     

Properties of electrolyte solutions relevant to high concentration chloride leaching. II. Density, viscosity and heat capacity of mixed aqueous solutions of magnesium chloride and nickel chloride measured to 90 °C

Results of density and viscosity measurements for aqueous solutions of MgCl₂ (0.5–3.5 mol L^− 1) and MgCl₂ + 10% NiCl₂ (0.5–3.5 mol L^− 1) at temperatures of 25, 60 and 90 °C show an almost linear increase in density with total concentration, while low nickel contents and temperature have comparatively small effects. Viscosities of MgCl₂ solutions rise sharply at 25 °C but are significantly lower at 90 °C. The viscosity of 3–4 mol kg^− 1 MgCl₂ at 90 °C is similar to water at 25 °C. Nickel has no significant effect on the viscosity of these solutions.Results of heat capacity measurements for aqueous solutions of MgCl₂ (0.5–3.5 mol L^− 1) and MgCl₂ + 10% NiCl₂ (0.5–3.5 mol L^− 1) at temperatures of 60 and 90 °C show that the heat capacities of these solution decrease significantly with total concentration, while the effects of low nickel contents and temperature are again comparatively small.     

印尼某红土矿硫酸加压浸出矿物组成变化研究

印尼苏拉威西岛La-paopao矿区红土镍矿储量约7326万吨,含镍约为1.25%,以此红土镍矿为对象,系统分析了矿样中主要矿物的种类、赋存状态及产出特征。结果表明:矿样含Fe(40.15%),Ni(1.42%),Co(0.15%),Mg(0.37%),SiO₂(6.92%)(质量分数),是典型的褐铁型红土镍矿;组成矿物主要为针铁矿、水针铁矿、高岭石、硬锰矿等;镍钴主要以类质同象或在结晶过程中以机械夹杂形式分布于褐铁矿中,其次分布于硬锰矿中,还有部分以独立矿物镍钴土矿形式存在。基于矿物特征,采用硫酸高压浸出工艺处理该红土镍矿,在最佳工艺条件下,镍浸出率超过96%,钴浸出率在97%以上,铁浸出率小于1%,实现了镍钴选择性提取。最后分析了渣中残余镍、钴未能浸出的原因以及各金属的浸出行为。未浸出镍钴部分可能存在于锰土矿中,另一部分则在Fe³⁺和Al³⁺高温水解沉淀过程中被夹带进入浸出渣。在高温下Fe³⁺强烈水解并释放出酸,Al³⁺大部分水解并释放出酸,并沉淀入渣。     

Elevated-pH bioleaching of a low-grade ultramafic nickel sulphide ore in stirred-tank reactors at 5 to 45 °C

This study is a continuation of previous work designed to assess the effect of elevated-pH bioleaching on a low-grade ultramafic nickel sulphide ore from Manitoba, Canada. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as lizardite, making processing of the ore difficult with conventional pyro- and biohydrometallurgical techniques. This work has two objectives: to maximize nickel extraction, and to minimize magnesium mobilization. Five-week stirred-tank bioleaching experiments were conducted with finely ground ore (− 147 µm) at three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C). The initial rate of nickel extraction from pentlandite was observed to be inversely correlated to acidity at all temperatures, while the final extraction of nickel after 5 weeks was determined to be moderately correlated to acidity at high temperatures and negatively correlated to acidity at low temperatures. The advantage of elevated-pH bioleaching was most evident at 5 °C, in which the final extraction of nickel at pH 5 was approximately 250% greater than at pH 3. Electron probe X-ray microanalysis of the post-leach residues revealed that the un-reacted lizardite was enriched with nickel during experiments conducted at pH 5, and that the extent of enrichment was a strong function of temperature. The undesirable extraction of magnesium exhibited a strong negative pH–temperature interaction and the consumption of sulphuric acid directly tracked the extraction of magnesium over all experimental conditions. Bioleaching at elevated pH substantially increased the ratio of nickel to magnesium in the leachate, and resulted in a substantial reduction in sulphuric acid consumption.     

Leaching behavior of metals from a limonitic nickel laterite using a sulfation–roasting–leaching process

The leaching behavior of metals from a limonitic laterite was investigated using a sulfation–roasting–leaching process for the recovery of nickel and cobalt. The ore was mixed with water and concentrated sulfuric acid followed by roasting and finally leaching with water. Various parameters were studied including the amount of acid added, roasting temperature and time, sample particle size, addition of Na₂SO₄ and solid/liquid ratio in leaching process. More than 88% Ni, 93% Co and < 4% Fe are extracted under the determined conditions. Simultaneously, about 90% Mn and Cu, 70% Mg, 45% Al, 25% Zn, 4% Cr and Ca are extracted respectively. The pH of the leach solution is about 2. The leaching efficiency is independent of sample particle size due to decomposition of ferric sulfate formed during roasting. The roasted mass was characterized by various physico-chemical techniques such as DSC/TGA, XRD and SEM. This process provides a simple and effective way for the extraction of nickel and cobalt from laterite ore.     

Studies on the leaching of an arsenic–uranium ore

Preliminary leaching studies were carried out to develop a suitable method for the recovery of uranium and the elimination of arsenic from a low grade carbonate/silicate ore containing 64 ppm U and 2446 ppm As, as well as some Cu, Pb, Ni and Zn. An examination of the mineralogy found mostly uranium(VI) minerals, such as uraninite, and various base metal sulfides and arsenates in veins and fissures. Roasting the ore at 500–800 °C to volatilize arsenic proved to be unsuitable. Therefore, the ground ore was subjected to direct leaching with sulfuric acid, sodium sulfide and ferric chloride at 80–90 °C with a liquid to solid ratio of 1:1. With sulfuric acid at a concentration of 180 kg/t ore, complete recovery of both uranium and arsenic was achieved giving undesirable arsenic in the leach liquor. The maximum recovery of uranium and arsenic by leaching with sodium sulfide was only 20% and 18%, respectively. However, 3 M ferric chloride leached approximately 92% U(VI) and precipitated arsenic as ferric arsenate. Therefore, maximum uranium can be extracted and arsenic eliminated as impurity by selective leaching with ferric chloride.     

某红土型镍矿中镍钴的赋存状态对其回收的影响

褐铁矿型红土镍矿是一种富含镍、钴、铁的重要资源,综合利用价值巨大。探究红土型镍矿中镍和钴的赋存状态,以深入了解赋存状态对镍和钴回收利用的影响。通过详细的工艺矿物学研究,明确镍和钴主要赋存于褐铁矿、锰的水合氧化物和锰镍矿中,根据该红土型镍矿特征判断最佳冶炼回收方法为高压酸浸工艺。研究为红土型镍矿的资源高效利用提供了重要参考,为相关工业应用和环境保护提供了有益启示。     

红土镍矿加压浸出工艺残积型红土镍矿中和试验研究

残积型红土镍矿是一种重要的红土镍矿,镁元素含量较高(10％～27％),在红土镍矿加压浸出项目中,通常用来中和加压浸出的矿浆,矿浆中硫酸浓度通常为30 ～ 50 g/L.但残积矿用量对镍、钴浸出率有较大影响,为了更好地利用残积型红土镍矿,本文进行了常规浸出试验和还原浸出试验.试验结果表明:随着残积矿用量的增加(液固比降低...     

红土镍矿微波水热法浸提镍钴

采用微波水热盐酸浸出方法对腐泥土型红土镍矿提取镍钴进行了研究,详细探讨了焙烧预处理、微波水热浸出温度和浸出时间对镍钴浸出率的影响.对于300℃焙烧预处理后的红土镍矿,微波水热温度为50℃,浸出时间为1 h时,镍的浸出率高达93.65%,钴的浸出率为87.86%.红土镍矿的微波水热浸出体系与普通水热浸出体系相比,镍和钴的浸出效果更好.研究表明,扩散过程是镍、钴浸出过程的主要限制环节.      

Pressure leaching of copper converter slag using dilute sulphuric acid for the extraction of cobalt, nickel and copper values

In our earlier studies [1–4], conditions were optimized for leaching converter slag with ferric chloride/dilute sulphuric acid for the recovery of cobalt, nickel and copper. By using both leachants most of the copper, nickel and cobalt values could be solubilized. Subsequent treatment of the leach liquors for separation and recovery of metals was difficult due to the presence of large quantities of iron in relation to other metal concentrations. In the present work, an attempt has been made to develop a process based on pressure leaching of the slag with dilute sulphuric acid in which iron contamination could be minimized by oxidation and hydrolysis. Various parameters including leaching time, pulp density, particle size, concentration of acid and oxygen partial pressure were studied to optimize the solubility of metal values. Under optimum conditions about 90% copper and more than 95% each of nickel and cobalt could be extracted with only 0.8% extraction of iron.     

Extraction of vanadium from black shale using pressure acid leaching

The extraction of vanadium from black shale was attempted using pressure acid leaching. The effects of the several parameters which included reaction time, concentration of sulfuric acid, leaching temperature, liquid to solid ratio and concentration of additive (FeSO₄) upon leaching efficiency of vanadium were investigated and a two-step counter-current leaching approach was developed. The results showed that the leaching efficiency of vanadium in the two-step process could reach above 90%. Vanadium was effectively separated and enriched by solvent extraction after leachate pretreatments, including the reduction of Fe³⁺ and adjustment of pH value. The extraction and stripping yields of vanadium were both > 98%. Ammonia was added to a stripping liquor to precipitate vanadium and then the ammonium poly-vanadate produced was calcined at 550 °C for 3 h to produce the high purity V₂O₅ powder. The overall yield of vanadium through all process stages was about 85%.     

Properties of electrolyte solutions relevant to high concentration chloride leaching. III. Solubility of pertinent solids and iron(III)/iron(II) redox potential measured in concentrated magnesium chloride solutions

Results of solubility measurements of nickel chloride, manganese chloride, iron(II) chloride, hematite and akaganeite in aqueous solutions of MgCl₂ (0.5–3.5 mol L^− 1) at temperatures of 60 and 90 °C are reported. Solubilities of metal(II) chlorides decrease almost linearly with MgCl₂ concentration due to the common ion effect. Nickel chloride and iron(II) chloride solubilities are very similar, while manganese chloride is about 30% more soluble.Hematite is more stable (i.e. less soluble) than akaganeite under all conditions investigated in this study, while ferrihydrite is considerably less stable. In other words, there is no change in the relative stabilities of these phases effected by the presence of high magnesium chloride concentrations. The solubility of all of these phases decreases with temperature and, for each temperature, the solubility constants increase linearly with the MgCl₂ concentration. The present results allow the prediction of the iron concentration as a function of the H⁺ and MgCl₂ molality at equilibrium with hematite or akaganeite.The Fe(III)/Fe(II) redox behaviour has been characterized in concentrated aqueous solutions of MgCl₂ (1.5–3.5 mol L^− 1) at a temperature of 25 °C. Standard redox potentials are ca. 100 mV lower than at infinite dilution and change linearly by only 13 mV in the range 2–4 mol L^− 1 MgCl₂.     

Leaching of a limonitic laterite in ammoniacal solutions with metallic iron

The leaching of a limonitic laterite (containing approximately 1% Ni, 0.1% Co and 50% Fe) was studied in ammoniacal solution. The laterite was leached in the presence of metallic iron which acted as a reductant. The kinetic parameters studied included the effect of temperature, metallic iron concentration, total ammonia concentration and ammonium sulphate to ammonium hydroxide ratios. Tests were performed in a batch cell with temperature ranging from 50 to 80 °C at atmospheric pressure. The kinetic behavior for nickel and cobalt extraction was observed to be different. Cobalt extraction was initially faster than nickel and it showed good extractions at lower temperatures, however, after reaching a maximum value of approximately 80%, extraction decayed by as much as 50%. This was likely due to cobalt co-precipitation and/or adsorption into iron and/or manganese oxides and hydroxides which could form during the process. Cobalt losses tended to increase with temperature, total ammonia concentration, ammonium hydroxide to ammonium sulphate ratio and metallic iron concentration. Nickel extraction was increased by higher temperature, total ammonia concentration and metallic iron concentration up to a maximum of roughly 70% after 48 h at 80 °C.Through feed and solid residue analysis, by X-ray diffraction and SEM, it was possible to characterize and understand how the feed mineral reduction occurred. The main phases present in the feed and residue were goethite and magnetite, respectively. Results suggest that the reduction occurs through two main reactions. First, the reaction between goethite and metallic iron produced Fe(II) ammines. The Fe(II) ammines are capable of reducing goethite and producing magnetite. The Fe(II) ammines play an important role because they accelerate the reduction and favor the extraction kinetics of nickel. The main advantage of using metallic iron as a reducing agent is the possibility of generating an autocatalytic system.     

Leaching of chalcopyrite with Brønsted acidic ionic liquid

A Brønsted acidic ionic liquid 1-butyl-3-methyl-imidazolium hydrogen sulphate ([bmim]HSO₄) and its aqueous solutions were used for the leaching of chalcopyrite concentrate at ambient pressure under air in the temperature range of 50 to 90 °C. Copper extraction increased from 52% to 88% as the ionic liquid concentration in solution increased from 10% (v/v) to 100%. Copper extraction was very low at temperatures below 70 °C, but increased significantly at temperatures from 70 to 90 °C, suggesting a high activation energy for the chemical reaction. Elemental sulfur formed a solid layer surrounding the surface of unreacted core during the leaching to affect the reagent diffusion and limit the leaching rate. Hydrogen ion, released by the ionic liquid, and dissolved oxygen were determined to be foremost responsible for the oxidative leaching of chalcopyrite. Compared with leaching of chalcopyrite in acidic aqueous sulphate solutions, the pure ionic liquid and its aqueous solutions exhibited easier leaching of chalcopyrite at higher temperatures which is attributed to increasing the oxygen solubility and transfer of dissolved oxygen to speed up the oxidation reaction.     

Reductive leaching of manganese from low-grade manganese ore in H2SO4 using cane molasses as reductant

Manganese extraction from a low-grade ore was investigated using cane molasses as a reducing agent in dilute sulfuric acid medium. The effects of concentrations of cane molasses and sulfuric acid, leaching temperature as well as reaction time were discussed. The results showed that high manganese recovery with low Fe and Al extraction yield could be obtained by analyzing the leaching efficiencies of Mn, Fe and Al during the leaching process. The optimal leaching condition was determined as 1.9 mol/L H₂SO₄ and 60.0 g/L cane molasses for 120 min at 90 °C while using particles smaller than 0.147 mm. The leaching efficiencies were 97.0% for Mn, whereas 21.5% for Al and 32.4% for Fe, respectively.