Leaching behavior of metals from limonitic laterite ore by high pressure acid leaching

The leaching behavior of metals from a nickeliferous limonitic laterite ore was investigated by high pressure acid leaching process for the extraction of nickel and cobalt.The effects of sulfuric acid added,leaching temperature,leaching time and liquid/solid（L/S） ratio on metals extraction were examined.More than 97% Ni,96% Co,93% Mn,95% Mg and less than 1% Fe are extracted under optimum conditions.Analysis of the high pressure acid leaching residue by chemical and XRD analysis indicates that the residual iron and sulfur are mainly present in phases of hematite and alunite,respectively.The high pressure leaching process provides a simple and efficient way for the high recovery of nickel and cobalt from laterite ore,leaving residue as a suitable iron resource.

Microwave assisted atmospheric acid leaching of nickel from laterite ore

The recovery of nickel from laterite ore with sulphuric acid under the effect of microwave irradiation was studied.The experimental results indicated that the extraction rate of nickel was influenced by reaction time,sulphuric acid concentration,and temperature,especially by microwave power.The results obtained from the experiments of orthogonal arrays showed that the optimum conditions of sulphuric acid concentration,reaction time,microwave power,and temperature were 25 vol.%,1.5 h,600 W,and 90°C,respectively.Under the optimal conditions,the nickel recovery could reach approximately 90.8%,which was higher than that obtained by conventional water bath heating.Kinetic experiments showed that the leaching of nickel in a sulphuric acid medium was controlled by chemical reaction occurring on the surface of laterite ore.The apparent activation energy was 38.9 kJ/mol.Microwave heating technology is efficient,clean,and easy to control and facilitate continuous processing of materials.

Extraction of molybdenum and nickel from roasted Ni-Mo ore by hydrochloric acid leaching, sulphation roasting and water leaching

To extract molybdenum and nickel from the roasted Ni-Mo ore, a process of hydrochloric acid leaching, sulphation roasting and water leaching was investigated. The results showed that this process could get a high leaching rate of Mo and Ni. Under the optimum conditions of hydrochloric acid leaching （roasted Ni-Mo ore leached with 0.219 mL/g hydrochloric acid addition at 65 ℃ for 30 min with a L/S ratio of 3 mL/g）, sulphation roasting （51.9% sulfiaric acid addition, roasting temperature 240 ℃ for 1 h）, followed by leaching with the first stage hydrochloric acid leaching solution at 95 ℃ for 2 h, the leaching rates of Mo and Ni reached 95.8% and 91.3%, respectively.

Evolution of ferronickel particles during the reduction of low-grade saprolitic laterite nickel ore by coal in the temperature range of 900–1250℃with the addition of CaO–CaF_(2)–H_(3)BO_(3)

The method of producing ferronickel at low temperature(1250–1400℃)has been applied since the 1950s at Nippon Yakin Kogyo,Oheyama Works,Japan.Limestone was used as an additive to adjust the slag composition for lowering the slag melting point.The ferronickel product was recovered by means of a magnetic separator from semi-molten slag and metal after water quenching.To increase the efficiency of magnetic separation,a large particle size of ferronickel is desired.Therefore,in this study,the influences of CaO,CaF_(2),and H_(3)BO_(3) additives on the evolution of ferronickel particle at≤1250℃were investigated.The experiments were conducted at 900–1250℃with the addition of CaO,CaF_(2),and H_(3)BO_(3).The reduction processes were carried out in a horizontal tube furnace for 2 h under argon atmosphere.At 1250℃,with the CaO addition of 10 wt%of the ore weight,ferronickel particles with size of 20μm were obtained.The ferronickel particle size increased to 165μm by adding 10 wt%CaO and 10 wt%CaF_(2).The addition of boric acid further increased the ferronickel particle size to 376μm,as shown by the experiments with the addition of 10 wt%CaO,10 wt%CaF_(2),and 10 wt%H_(3)BO_(3).

Extraction of valuable metals from low-grade nickeliferous laterite ore by reduction roasting-ammonia leaching method

Nickel and cobalt were extracted from low-grade nickeliferous laterite ore using a reduction roasting-ammonia leaching method.The reduction roasting-ammonia leaching experimental tests were chiefly introduced,by which fine coal was used as a reductant.The results show that the optimum process conditions are confirmed as follows:in reduction roasting process,the mass fraction of reductant in the ore is 10%,roasting time is 120 min,roasting temperature is 1 023-1 073 K;in ammonia leaching process,the liquid-to-solid ratio is 4:1(mL/g),leaching temperature is 313 K,leaching time is 120 min,and concentration ratio of NH3 to CO2 is 90 g/L:60 g/L.Under the optimum conditions,leaching efficiencies of nickel and cobalt are 86.25% and 60.84%,respectively.Therefore,nickel and cobalt can be effectively reclaimed,and the leaching agent can be also recycled at room temperature and normal pressure.

Transformation and leaching kinetics of silicon from low-grade nickel laterite ore by pre-roasting and alkaline leaching process

The mineralogical phase transformation of a low-grade nickel laterite ore during pre-roasting process and the extraction of silicon during alkaline leaching process were investigated.The results indicate that the reaction activity of nickel ores is effectively improved by pre-roasting at650°C for2h,because of the transformation of lizardite into magnesium olivine and protoenstatite.When finely ground ore samples(44-61μm)pre-roasted firstly react with sodium hydroxide solution(60g/L)with a solid/liquid ratio of1:5at140°C for120min,the extraction of silicon can reach89.89%,and the other valuable elements of magnesium,iron and nickel are accumulated in the solid residues.The leaching kinetics of nickel laterite ore can be described successfully by the diffusion through the product layer control model.The activation energy is calculated to be11.63kJ/mol and the kinetics equation can be expressed as1-3(1-x)2/3+2(1-x)=13.53×10-2exp[-11.63/(RT)]t.

Kinetic study on leaching of nickel from Turkish lateritic ore in nitric acid solution

Dissolution kinetics of nickel from lateritic ore in nitric acid solution was investigated. Experimental parameters used were stirring speed(100-600 r/min), temperature(40-96 °C), nitric acid concentration(0.1-2 mol/L) and particle size(<106 μm). The shrinking core model was applied to the results of experiments investigating the effects of leaching temperature in the range of 40-90 °C and nitric acid concentration in range of 0.1-2 mol/L on nickel dissolution rate. The kinetic analysis shows that the nickel dissolution from lateritic ore could be described by diffusion model. The activation energy(E_a) for the dissolution reaction is calculated as 79.52 kJ/mol.

Synthesis and characterization of Co_3O_4 prepared from atmospheric pressure acid leach liquors of nickel laterite ores

A chemical precipitation-thermal decomposition method was developed to synthesize Co3O4 nanoparticles using cobalt liquor obtained from the atmospheric pressure acid leaching process of nickel laterite ores. The effects of the precursor reaction temperature, the concentration of Co2＋, and the calcination temperature on the specific surface area, morphology, and the electrochemical behavior of the ob- tained Co304 particles were investigated. The precursor basic cobaltous carbonate and cobaltosic oxide products were characterized and ana- lyzed by Fourier transform infrared spectroscopy, thermogravimetric differential thermal analysis, X-ray diffraction, field-emission scanning electron microscopy, specific surface area analysis, and electrochemical analysis. The results indicate that the specific surface area of the Co3O4particles with a diameter of 30 rim, which were obtained under the optimum conditions of a precursor reaction temperature of 30℃, 0.25 mol/L Co2＋, and a calcination temperature of 350℃, was 48.89 m2/g. Electrodes fabricated using Co3O4 nanoparticles exhibited good electrochemical properties, with a specific capacitance of 216.3 F/g at a scan rate of 100 mV/s.

Leaching of magnesium from desiliconization slag of nickel laterite ores by carbonation process

The leaching of magnesium from desiliconization slag of nickel laterite ores by carbonation process was studied.The influence of various parameters was investigated to optimize the conditions and determine the kinetics of the reaction.The results show that with increasing stirring speed,liquid-to-solid ratio and reaction time,and decreasing temperature,the leaching rate of magnesium enhances.The leaching process of the desiliconization slag in the range of 288-298 K is controlled by the surface chemical reaction model.The apparent activation energy is-20.45 kJ/mol,and the kinetics model is obtained.

Leaching of nickel laterite ore assisted by microwave technique

The application of microwave technique in the hydrometallurgy of nickel laterite ores was described.The mixture of nickel laterite ores and sulfuric acid was pre-treated by microwave irradiation.The dissolving of nickel was conducted in hot water at the atmospheric pressure.The effects of factors,such as microwave power,microwave irradiation time,and sulfuric acid dosage, were investigated.In microwave field,the migration of ionic species and/or rotation of dipolar species promote the liquid?solid reaction process due to the increased contact area of reactants and leaching reaction rate constant.Thanks to the strengthening action of microwave,the microwave-assisted leaching process has its advantages,such as higher extracting rate than conventional atmospheric leaching,and no need for high-pressure operation as high pressure acid leaching(HPAL).The ferric iron in leaching solution could be effectively removed by sodium jarosite process with a little loss of nickel in the jarosite precipitate.

Microwave pretreatment for enhanced selective nitric acid pressure leaching of limonitic laterite

As clean energy,the microwave is commonly used to pretreat various ores.In this work,the microwave dielectric properties of limonitic laterite ore were measured by resonant cavity perturbation technique and the effects from microwave were systematically investigated.Results indicated that limonitic laterite had high microwave absorbance.After microwave pretreatment,the microstructure of the laterite became less aggregated and more porous and the main phase transformed from goethite to hematite that improved leaching in nitric acid(1.2 kg HNO3/kg ore);Ni,Co,Fe,and Mg extraction ratios were 95.2%,98.1%,1.8%and 15%,respectively,after leaching for 60 min at 200°C and 500 r/min.Furthermore,in the process of goethite to hematite by microwave pretreatment,the nickel-containing mineral is activated,which makes nickel be leached easily.The leaching process has high Ni extraction ratio compared to that without microwave(82%)and conventional pretreatment(90.4%).Therefore,microwave pretreatment of limonitic laterite before nitric acid pressure leaching is an effective way to improve the selectivity and extraction of the leach.

Dissolution of lateritic nickel ore using ascorbic acid as synergistic reagent in sulphuric acid solution

The dissolution of nickel and cobalt from Caldag lateritic nickel ore using the combination of sulphuric and ascorbic acids was investigated. The use of other organic acids, namely citric, maleic and stearic acids, as synergistic reagents was studied for comparison. The results revealed that the use of ascorbic and citric acids markedly improved the dissolution of cobalt compared to the other two organic acids that only showed slight synergistic effect on the leaching rate. In terms of nickel dissolution, ascorbic acid is the most effective synergist, followed by citric, maleic and stearic acids in descending order. Under the most optimized conditions found in this study, i.e., using 1 mol/L of sulphuric acid with the presence of 4 g/L of ascorbic acid at 80 ℃and solid-to-liquid ratio of 1/10, more than 99% and 98% leaching rates of cobalt and nickel, respectively, can be achieved within 4 h of leaching. In addition, the leaching performance is relatively insensitive to the change of ascorbic acid concentration from 2 to 4 g/L which is highly desirable from operational perspective.

Pressure nitric acid leaching of alkali-pretreated low-grade limonitic laterite

The pressure nitric acid leaching of alkali-pre- treated low-grade limonitic laterite, as well as removing impurity AI（III） and preparing intermediate product of nickel/cobalt sulphide from leaching liquor were investi- gated. After pretreatment, iron exists in the form of amorphous iron oxides, while nickel is adsorbed on the surface of iron oxides in the form of nickel oxide. The preferable pressure leaching conditions are determined as follows： leaching temperature of 458 K, leaching duration of 60 min, initial acidity of nitric acid of 1.90 mol.L-~ and liquid to solid ratio of 3：1 （volume to mass ratio）. Under these conditions, the leaching efficiencies of Ni, Co and A1 are 95 %, 88 % and 55 %, respectively, and that of Fe is less than 1%. The loss rates of Ni and Co are 1.8 % and 1.5 %, respectively, during the step of removing impurity AI（III）. The sulphide precipitation process produces the interim production of nickel/cobalt sulphides, recovering greater than 99 % of Ni and Co in the purified solution. The iron-rich （〉60 %） pressure leaching residue with low Cr, S can be further reclaimed as the raw materials for iron making.

Nickel extraction from low grade laterite by agitation leaching at atmospheric pressure

This research work deals with the extraction of nickel from a low grade nickel laterite ore, taken from a deposit located in southwestern of Iran, through agitation leaching at atmospheric pressure. The assaying and mineralogical studies carried out on the nickel laterite sample, showed the 0.88% Ni, and principally consisted of oxide and silicate crystalline phases i.e. dolomite, quartz, magnetite, and goethite. Among numerous factors affecting such process, four major parameters i.e. temperature, agitator speed(r/min), leaching agents and their concentration were considered in a two-level full factorial experimental design. The agitation leach tests showed that the ore could be leached at atmospheric pressure with sulfuric acid while citric acid was almost unpromising. Analysis of variance(ANOVA) using DX7 software was employed to identify effective parameters. Sulfuric acid concentration and temperature were the most effective parameters on Ni extraction. Furthermore, the factorial models for experiment responses were developed. The results showed 83% Ni extraction after 4 h leaching, under optimized conditions i.e.temperature at 95 ℃, acid concentration at 5 N and agitator speed at 1000 r/min. This study revealed that factorial experimental design can be implemented to identify effective parameters on the agitation leaching process of nickel laterite.

Activation pretreatment of limonitic laterite ores by alkali-roasting using NaOH

Activation pretreatment of Cr-containing limonitic laterite ores by NaOH roasting to remove Cr, Al, and Si, as well as its effect on Ni and Co extraction in the subsequent pressure acid leaching process was investigated. Characterization results of X-ray diffraction （XRD） and scanning electron microscopy/X-ray energy dispersive spectroscopy （SEM/XEDS） show that goethite is the major Ni-bearing mineral, and chromite is the minor one. Experimental results show that the leaching rates of Cr, Al, and Si are 95.6wt%, 83.8wt%, and 40.1wt%, respectively, under the optimal alkali-roasting conditions. Compared with the direct pressure acid leaching of laterite ores, the leaching rates of Ni and Co increase from 80.1wt% to 96.9wt% and 70.2wt% to 95.1wt% after pretreatment, respectively. Meanwhile, the grade of acid leaching iron residues increases from 54.4wt% to 62.5wt%, and these residues with low Cr content are more suitable raw materials for iron making.

褐铁矿型红土镍矿中有价金属的酸浸工艺

镍是一种战略性稀有金属,从低品位红土镍矿中生产单质镍或镍的合金是解决镍铁合金需求的主要途径。采用盐酸选择性浸出印尼褐铁矿型红土镍矿中的有价金属,结果表明:当盐酸浓度10 mol/L,原料粒度74μm,浸出温度353 K,固液体积比1∶4,浸出时间120 min时,镍、钴、锰、铁和镁的浸出率分别为34.3%、90.67%、64.23%、76.46%和48.12%,且盐酸作为常见的工业副产品,易回收再生。镍、钴、锰的浸出动力学研究可知,其浸出过程不符合广泛采用的收缩核模型,而用Avrami方程进行拟合具有很好的线性,根据Arrhenius公式求得浸出过程中镍、钴和锰的表观活化能分别为7.96、4.00kJ/mol和4.98 kJ/mol,三者浸出的活化能值均介于4~12 kJ/mol范围内,且浸出温度对反应速率常数的影响并不明显,判断出镍、钴和锰的浸出过程受扩散条件控制。本研究结果可为褐铁矿型红土镍矿的高效开发利用提供理论参考。

褐铁型红土镍矿硫酸高压浸出矿物结构变化

菲律宾某矿区典型褐铁型红土镍矿的工艺矿物学分析表明,矿样中主要的矿物为针铁矿、铬尖晶石、石英及其他黏土质矿物,镍、钴主要赋存在铁矿物中。基于矿物特性,选择采用硫酸高压浸出工艺对该矿物进行处理,在100 g矿酸用量29 g、温度250℃、液固比3 mL/g、反应时间30 min的条件下,镍、钴浸出率均超过95%,铁浸出率低于1%,实现了镍、钴的选择性浸出。浸出渣的工艺矿物学分析表明,浸出过程中,原矿中的针铁矿矿相被破坏,赋存在其中的镍、钴被浸出进入溶液,未被浸出的镍、钴赋存于铬尖晶石中,这是镍、钴浸出不完全的主要原因。浸出渣中主要的含硫物相是铝水解生成的明矾石和铁水解夹带的部分硫酸镁等硫酸盐,二者均与铁矿物结合较紧密。

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。

高铁低品位红土镍矿酸浸工艺研究

研究了用硫酸从印尼某高铁低品位红土镍矿中加压酸浸镍、钴、铁,并探讨了浸出渣中铁品位变化及常压、加压下的浸出动力学。结果表明:在酸矿比260 kg/t、温度250℃(对应水蒸气压力4.0 MPa)、液固体积质量比3/1、搅拌速度300 r/min、粒度100目、反应时间1 h条件下,镍、钴、铁浸出率分别为98.1%、98.3%、4.7%,铁品位可达51.3%;加压和常压下,镍、钴浸出过程均符合界面化学反应控制的收缩核模型,加压下反应活化能分别为116、91 kJ/mol,常压下反应活化能分别为41、53 kJ/mol;常压下主要是针铁矿的浸出,高压下主要是铬铁矿、磁铁矿等矿相的浸出。

红土镍矿高压酸浸技术优化研究

近年来,印度尼西亚掀起高压酸浸项目投资热潮,多个项目已投产或处于规划中。项目一般由中方背景主导,技术成熟,装备可靠,单位投资较低,建设速度较快,运营经验丰富,爬坡期较短,单线产能大,装备国产化趋势明显。高压酸浸(High Pressure Acid Leach,HPAL)技术优化涉及4个重点,一是提高原矿浆浓密底流浓度,二是预热方式优化,三是一段沉镍钴流程优化,四是沉镍钴沉淀剂优化。高压酸浸技术主要有5个发展方向,即尾渣综合利用、关键设备国产化替代、增加高压釜长度、配矿和锰综合回收利用。本文结合近年来红土镍矿高压酸浸技术的发展特点,分析高压酸浸技术优化重点,指出高压酸浸技术发展方向,为新建项目的规划和运营提供有效指导。