硝酸常压浸出红土镍矿特性及镍浸出动力学

采用ICP和XRD分析手段研究了某红土镍矿的元素及物相组成.采用硝酸常压浸出该红土镍矿.通过单因素条件实验和综合实验探究了硝酸浓度、固液比、搅拌转速、浸出时间、浸出温度在常压条件下对红土镍矿中Ni、Co、Fe和Mg浸出的影响,并求解了镍的浸出动力学.结果表明,该红土镍矿为硅镁型,在硝酸浓度5 mol/L、固液比(g/m...     

Gangue–reagent interactions during acid leaching of uranium

During the acid leaching of uranium, gangue–reagent interactions have both negative and positive consequences. Gangue dissolution increases reagent costs, and in some cases can prevent the economic acid leaching of an ore, but can also increase uranium mineral exposure and improve recoveries. Due to rapid dissolution kinetics, the acid consumption characteristics of the various carbonate species are readily predicted, however the same is not true of silicate gangue. Due to factors including slower leach rates, incongruent dissolution, parabolic kinetics, and surface area, pH and temperature dependence, the gangue acid consumption characteristics of silicate minerals are significantly more complex. A detailed mineralogical investigation and acid leach tests were conducted on sandstone-hosted uranium ore samples. The dissolution characteristics of the more common gangue phases were determined. The study demonstrated that gangue–reagent interactions can be predicted from mineralogical data, thus reducing technical risk during processing.     

Acid leaching and rheological behaviour of a siliceous goethitic nickel laterite ore: Influence of particle size and temperature

This study investigates the isothermal, batch, H₂SO₄ acid leaching behaviour of siliceous goethitic (SG) nickel (Ni) laterite ore and its links to pulp rheology. Specifically, the effect of feed ore particle size (−0.2 vs −2.0 mm), leaching temperature (70 vs 95 °C) and pulp rheology on Ni and pay metal, cobalt (Co) extraction kinetics and yield was studied for 4 h on 40 wt.% solid dispersions at pH 1. The leaching behaviour was distinctly incongruent, reflecting the disproportionate proliferation of major gangue mineral’s constituent elements (e.g., Fe, Al, Mg, Na, Si) alongside Ni and Co in the pregnant leach solution. At 70 °C, Ni/Co extraction rates were notably lower (<20%) in contrast with 95 °C where a significant increase in Ni/Co extraction to 78/77% and 74/77%, respectively, for the −0.2 and −2.0 mm feeds occurred. The slurries displayed a non-Newtonian, shear thinning Bingham plastic rheological behaviour of which the viscosity and shear yield stress increased markedly in the course of 4 h leaching. The pulp viscosity and shear yield stress were greater at lower temperature than at higher temperature and they were also greater in slurries with finer than coarser feed particles. The dynamic pulp rheology, however, had no marked effect on the overall Ni/Co extraction rates. Whilst the feed ore particle size had no remarkable impact on overall Ni/Co extraction, it led to noticeably higher acid consumption and enhanced slurry rheology in the finer sized ore. The mechanism of leaching the SG ore followed a two-stage, first order chemical reaction-controlled shrinking core model, the kinetics of which gave higher rate constants and lower activation energies for the release of Ni, Co, Fe and Mg in the first stage. A faster leaching process involving more reactive minerals during the first 30 min is envisaged to be followed by leaching of the more refractory minerals.     

High pressure acid leaching of a refractory lateritic nickel ore

This paper describes the experimental findings of the extraction of nickel and cobalt by high pressure acid leaching (HPAL) of a refractory limonitic nickel laterite ore from the Gördes region of Manisa in Turkey. By optimizing the basic HPAL process parameters: leaching at 255 °C with 0.30 sulfuric acid to ore weight ratio with a particle size of 100% −850μ for 1 h of leaching, it was found that 87.3% of nickel and 88.8% of cobalt present in the ore could be extracted into the pregnant leach solution (PLS). However, these extraction results were found to be relatively low compared with other similar studies. In order to understand the possible reasons for this relatively lower extraction, further investigations have shown that together with a problem related to the kinetics of the dissolution reactions, a persistent acid resistant refractory mineral present in this sample also limited the leaching process. Attempts were made with different additives to solve this problem. The effects of chemical additives such as HCl, Na₂SO₄, FeSO₄, Cu⁺ and sulfur were tested and the effect of each addition on the degree of extraction of nickel and cobalt was determined.     

Kinetics of saprolitic laterite leaching by sulphuric acid at atmospheric pressure

Mineralogical analyses of the saprolitic laterite material have been characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermal analysis, scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDAX). Results showed that the saprolitic laterite material consists mainly of nickel-substituted lizardite showing the pebble-like morphology and traces of magnetite and phlogopite. Leaching results showed that as much as 84.8% nickel could be leached under the experimental conditions of 10% (v/v) H₂SO₄, 90 °C reaction temperature, leached within 5 min, particle size d₅₀ = 25 μm, stirring at 500 rpm and liquid to solid ratio 3:1. The kinetics of nickel and magnesium leaching from the saprolitic laterite material have been investigated in a mechanically stirred reactor and the activation energies were determined to be 53.9 kJ mol^?1 for nickel and 59.4 kJ mol^?1 for magnesium respectively, which are characteristic for a chemical reaction controlled process. The similarity of the activation energies of nickel and magnesium leaching from the saprolitic laterite material by sulphuric acid means that nickel in lizardite is loosely bound within the octahedral layer and almost all of the nickel could be leached simultaneously with magnesium but without complete decomposition of the silicate structure.     

輝锑矿浸出动力学的研究

本文针对目前湿法炼锑工艺过程研究的需要,对类似于辉锑矿浸出过程的液-固间歇式多相反应动力学模型进行了推导。用实际高价氯盐浸出辉锑矿的实验数据进行了验证。结果表明模型能较好地反映出实际过程的规律,并可以表示为:φ(R)=Kt。     

红土镍矿硫酸焙烧—浸出溶液中铁、镍回收的研究

以红土镍矿硫酸焙烧-浸出所得浸出液为原料,利用氨水调节溶液的pH值,进行铁、镍的分离与回收研究。通过探索温度、pH值对浸出液中铁、镍、镁离子沉淀的影响,得出沉淀铁离子的适宜条件为:温度30℃,pH=4.0,铁的沉淀率可达到99%以上,镍、镁沉淀率小于4%;沉淀镍离子的适宜条件为:温度60℃,pH=7.0,镍的沉淀率可达到95.5%以上,镁沉淀率低于10%。本研究所提出的分步水解法分离、回收有价金属的工艺将为红土镍矿硫酸法浸出液的综合利用提供技术指导。     

Innovative technology for processing saprolitic laterite ores by hydrochloric acid atmospheric pressure leaching

An innovative technology for processing saprolitic laterite ores from the Philippines by hydrochloric acid atmospheric leaching and spray hydrolysis is proposed. The factors that affect the hydrochloric acid atmospheric leaching of the laterite ores and spray hydrolysis of the atmospheric acid leach solution are investigated. Experimental results show that the leaching of Ni, Fe, and Mg is 98.9 wt%, 97.8 wt%, and 80.9 wt%, respectively, under optimal acid leaching conditions. The hydrolysis of Ni and Fe by the atmospheric acid leach solution approaches 100 wt% at the temperature range of 450–500 °C. Characterization results show that a serpentine mineral, nominally Mg₃Si₂O₅(OH)₄, is the major component and goethite, FeO(OH), is the minor one in the laterite ores. Treatment by hydrochloric acid atmospheric leaching breaks the mineral lattices of the laterite ores and makes amorphous silica the primary product in the atmospheric acid leach residue. The grade of Ni in the hydrolyzate increases to 4.55%. The hydrolyzate with high Ni content can be utilized for ferro-nickel production.     

红土镍矿酸浸渣综合利用进展

近年来随着不锈钢及新能源用镍需求的增长,红土镍矿湿法提镍工艺得到更多应用,相应的红土镍矿酸浸渣堆存量也迅速增加,对此类固废进行科学消纳和资源综合利用迫在眉睫。针对红土镍矿酸浸渣有害元素硫、有价金属铁含量高的特点进行综合利用新技术、新装备研究对红土镍矿湿法冶金工业的持续发展具有重要的理论和现实意义。本文主要介绍红土镍矿酸浸渣的湿法冶金形成过程及其成分组成和物理化学性质,较为系统地梳理了红土镍矿酸浸渣在尾矿坝堆积、地下压滤回填和深海填埋等直接处理方法,提取利用铁、铬、铝、稀土等有价金属资源,消纳制备硅藻土、陶粒、矿物纤维等建筑材料、制备锂电池电极、沸石等高附加值材料综合利用技术上的研究进展,展望了红土镍矿酸浸渣流态化降硫提铁技术及装备的发展前景。     

Assessing the energy and greenhouse gas footprints of nickel laterite processing

The energy and greenhouse gas footprints of some of the various technologies that are used for processing nickel laterite ores have been assessed using life cycle assessment methodology based largely on publicly reported inventory data. The results of the study were used to identify opportunities to improve the energy and greenhouse gas impacts of the various processes and to examine how they might be affected under different future scenarios such as falling laterite ore grades and the possible imposition of a carbon tax. The opportunities identified included the use of biochar as a fuel and reductant, along with slag waste heat recovery in ferronickel smelting, and the use of the emerging bath smelting technology for ferronickel production instead of the rotary kiln/electric furnace process. As a significant amount of the life cycle-based greenhouse gas emissions from the hydrometallurgical acid leaching processes are generated by acid neutralisation with lime or limestone, there may be opportunities to reduce these emissions by utilising other neutralising agents or possibly by considering non-acid leaching systems. Improving the energy efficiency of the electrowinning stage used to recovery nickel metal from the leach liquor is another possible way in which the sustainability of hydrometallurgical production of nickel from laterite ores could be improved.     

含铟锌浸渣中铟浸出动力学研究

本文以含铟锌浸渣为对象,研究其在硫酸溶液中的浸出动力学。考察了搅拌转速、硫酸浓度、三价铁浓度、反应温度和矿物粒度等实验条件对铟浸出速率的影响。结果表明：其浸出过程可用没有固体产物层生成的“未反应核收缩模型”描述;浸出反应的表观活化能为 J/mol;对硫酸浓度与三价铁浓度的表观反应级数分别为0.985与-0.096;含铟锌浸渣的浸出过程受化学反应控制。     

褐铁矿型红土镍矿硫酸高压浸出的研究

研究了褐铁矿型红土镍矿硫酸高压浸出过程中浸出温度和时间、硫酸用量对镍、钴、锰、铁、铝、镁、硅、铬浸出的影响。在浸出温度为250℃,浸出压力3.9 MPa,浸出时间为40 min,硫酸用量240kg/t干矿的优化条件下,镍,钴,锰的浸出率分别为96.8%,96.6%,98.7%,铁、铝、镁、硅的浸出率分别降低到2.6%,16.9%,61.8%,1.9%,铬的浸出率降低到0.7%,浸出液中的铬以Cr~(3+)的形式存在,浸出液中没有Cr~(6+)。静置分离试验表明,在此浸出条件下的浸出矿浆固液分离效率较高。扫描电镜分别对30、40、60 min浸出渣相微观形貌的分析表明,浸出30 min时针铁矿中Fe~(3+)绝大部分溶出并经过水解重新沉淀,延长浸出时间只是使铁相的等粒-圆粒状颗粒分布趋于均化。浸出渣相的主要成分为Fe_2O_3,(H_3O)Al_3(OH)_6(SO_4)_2,KAl_3(SO_4)_2(OH)_6及Si O_2。     

Agglomeration and column leaching behaviour of goethitic and saprolitic nickel laterite ores

Processability of complex, low-grade nickel (Ni) laterite ores via heap leaching is very limited due to some intractable geotechnical and hydrological challenges such as poor heap porosity/permeability and structural stability. This work presents some investigations on laboratory batch drum agglomeration and continuous column leaching behaviour of saprolitic (SAP) and goethitic (G) Ni laterite ores as part of the quest for an effective ore pre-treatment process for enhanced heap leaching. As a focus, the effect of ore mineralogy/chemistry on the agglomeration and column leaching behaviour of −2 mm (crushed from −15 mm run-of-mine) G and SAP Ni laterite ores was examined. To produce ∼5–40 mm agglomerates in <15 min, the SAP ore required a higher H₂SO₄ (30 wt.%) binder dosage compared with the G ore, although both ores displayed substantially similar, coalescence-controlled agglomeration mechanism. The resulting G agglomerates were more robust than the SAP ones based upon their compressive strength and acidic solution soak test measurements. However, over 100 days of continuous column leaching, the structural stability of the SAP agglomerate bed was slightly greater than that of G agglomerates, reflecting a lesser slump of the former. The pregnant leach solution analysis revealed greater Ni/Co extraction rates from the SAP than the G agglomerates. Whilst the total mass of acid consumed per ton dry ore processed was greater for the SAP ore, the total kg acid per kg Ni extracted was markedly lower. Incongruent leaching of gangue minerals’ constituent elements (e.g., Fe, Mn, Mg, Al and Si) occurred and contributed significantly to the overall acid consumption. The findings show the relevance of agglomeration and column leaching tests for providing useful information for plant designing and optimization of Ni laterite heap leaching operations.     

硅镁型红土镍矿脱羟基相变过程动力学研究

镍具有优良的物理化学性质,应用领域广泛,镍资源主要存在于硫化镍矿和红土镍矿中,目前红土镍矿正逐渐成为主要的镍提取原料,由于红土镍矿含水量大,在冶炼过程中通常要对矿石进行高温预处理,目的是为了去除矿石晶格里的羟基水以及预先还原部分金属,但这部分羟基水的脱除需要消耗大量能量,并且产生物相变化,对预还原及浸出都会产生影响,因此探究红土镍矿脱羟基过程的物相变化及动力学条件对后续加工作业具有重要的研究意义。本文利用热力学分析软件模拟计算了红土镍矿加热过程中可能发生的化学反应,并采用热重-差热分析及 XRD 分析研究了硅镁型红土镍矿加热过程的物相变化,从室温到1400°C范围内进行了5种升温速率的非等温动力学实验,在256.8°C、582.8°C和823.0°C 处有三个特征峰,分别对应褐铁矿脱羟基、蛇纹石脱羟基以及硅酸盐矿物的相变。采用非等温动力学模型求解来确定反应的表观活化能及指前因子,使用Flynn-Wall-Ozawa 法和Kissinger-Akahira-Sunose 法计算了蛇纹石脱羟基过程的活化能,并利用Satava-Sestak法对常用的30种机理函数进行拟合,保留符合条件的机理函数,确定 Avrami-Erofeev 方程的A1/3函数符合脱羟基过程,其积分形式为G(α)= [-ln(1-α)]3,求得蛇纹石脱羟基反应的活化能为258.71 kJ·mol-1, lnA为28.94 S-1,平均线性相关系数为 0.9951,蛇纹石脱羟基过程符合随机成核及随后生长模型。     

The effects of mineralogy on the biological leaching of nickel laterite ores

The amenability of limonite ore, the iron rich nickel laterite phase, was observed to be less than saprolite, the silicate rich phase, when subjected to biological leaching with heterotrophic microorganisms. To understand this difference, controlled leaching of the various nickel laterite minerals was conducted using citric acid to mimic the chemical action of the organisms and subsequent characterisation of the leached residues. The raw ore and the leached mineral residues were examined using high-resolution synchrotron based X-ray diffraction and optical microscopy. The possible contribution of electrosorption and solid porosity was also considered. The results suggest that although electrosorption contributes to nickel and cobalt losses, it is the structural changes induced by the acid in the minerals which effects the recovery of the metals. Citric acid was found to dehydroxylate saprolite minerals resulting in an unstable nickel oxide and thus making it susceptible to acid attack. This behaviour was not observed in the limonite ore, which was found to be poorly leached by citric acid.     

Enhanced hydrochloric acid leaching of nickel

Dissolution rates of nickel in hydrochloric acid with and without the presence of thiourea have been studied by means of rotating disc methods with solution analysis. In the absence of thiourea an apparent activation energy value of 61.1 ± 12.1 kJ. mol⁻¹ was determined. Such a high value is inconsistent with a diffusion controlled process and this was supported by the lack of dependency of the dissolution rate on rotational speed. A reaction controlled process is indicated. In 8.4 mol. dm⁻³ hydrochloric acid the thiourea concentration range producing optimum dissolution rates was 10⁻³ to 10⁻² mol. dm⁻³. At 70° C the rate of leaching was enhanced by some 105 %. Tests using radiochemical labelling of the sulphur and of the carbon separately in the thiourea molecule confirmed previous proposals, for cobalt dissolution, that hydrogen sulphide is produced as a by-product of the cathodic depolarisation reaction involving the thiourea and is adsorbed on the metal surface in the molecular state, forming activated anodic sites which enhance anodic dissolution. At the 10⁻¹ mol. dm⁻³ thiourea concentration level stimulation of the nickel dissolution process gave way to its partial inhibition with a maximum diminution at 30°C of 50 %.     

Atmospheric leaching characteristics of nickel and iron in limonitic laterite with sulfuric acid in the presence of sodium sulfite

Atmospheric leaching of nickel from limonitic laterite ores is regarded as a promising approach for nickel production, despite its low nickel recovery and slower leaching rate than high pressure acid leaching. Sulfur dioxide can enhance the sulfuric acid leaching of laterite, but its behavior for enhancing atmospheric sulfuric acid leaching was uncertain due to SO₂ losses and emission. In this study, sodium sulfite was used as a substitute for SO₂ gas in the leaching and the sulfuric acid leaching characteristics of Ni and Fe from a limonitic laterite in the presence of sodium sulfite were investigated. A linear correlation exists between the extraction of Ni and Fe, indicating the difficulty in selective leaching of Ni over Fe. Most nickel is isomorphically substituted within the goethite and it is difficult to dissolve in a high oxidation–reduction potential solution environment, resulting in a low nickel recovery. SO₂(aq) generated from the reaction of sodium sulfite in sulfuric acid solution, lowers the potential for the reducing reaction of FeOOH to give Fe²⁺, accelerating the iron extraction and nickel liberation from goethite.     

新疆某铀矿石浸出试验

为了给新疆某铀矿采用地面堆浸和井下原地爆破堆浸的采矿新方法恢复生产提供依据，对该矿矿石进行了试验室搅拌浸出和柱浸试验。试验结果表明，该矿矿石氧化剂耗量少、浸出时间短、酸耗较低，属易浸矿石。矿石粒度对浸出率影响较大，当粒度从-5mm增加到-20mm时，矿石的柱浸渣计浸出率从88.7％下降到75．2％。氧化剂可提高浸出液铀浓度，但提高幅度不大。     

Sulphuric acid leaching of mechanically activated copper sulphidic concentrate

In this study, the effect of mechanical activation was evaluated on the leaching efficiency of copper sulphidic concentrate in 0.5 M sulphuric acid medium. The mechanical activation of samples was performed by a high energy planetary ball mill under the atmospheric conditions. The results showed that there was an optimum time of MA, about 6 h, in which the leaching efficiency reaches its maximum value (42% for 7 h of leaching). The improvement of leaching efficiency due to mechanical activation can be attributed to the significant decrease of the size of particles and the intense structural disordering of particles.     

An experimental evaluation of the leaching kinetics of PGM-containing Ni-Cu-Fe-S Peirce Smith converter matte, under atmospheric leach conditions

In a first stage atmospheric leach in a typical Sherritt Ni-Cu matte leach process, a Ni-Cu-Fe-S Peirce Smith converter matte is contacted with recycled copper spent electrolyte (an aqueous copper sulphate/sulphuric acid solution) at 85 °C with the purpose of dissolving nickel, while simultaneously removing copper from solution. In the PGM industry, copper removal is also important because it serves as a leading indicator in the removal of Ir, Rh, and Ru from the spent electrolyte. The matte mainly consists of heazlewoodite, chalcocite/djurleite, a Ni-Cu alloy phase and inert spinel minerals (magnetite and trevorite). Nickel is leached from the matte by two mechanisms: (i) leaching by sulphuric acid and oxygen; and (ii) an anaerobic metal exchange reaction (cementation and metathesis) between cupric ions in solution and nickel in the matte, which is also responsible for the removal of copper from solution.This study investigates the oxidative and non-oxidative leaching of converter matte in a laboratory batch reactor, with attention specifically being given to the effects of initial copper and acid concentrations and their effects on leaching kinetics. Experimental conditions were varied based on a 2^N experimental design. The availability of oxygen for acid-leaching reactions was found to be the most important factor influencing copper removal and nickel extraction. A 63% nickel extraction could be achieved during oxidative tests vs. 22% in a non-oxidative test. This also indicates that cementation did not take place to a significant degree and that nickel leaching mostly took place via leaching by acid and oxygen. It is suspected that the low degree of copper removal can be attributed to the solids/reactants ratio was employed in tests. The initial copper and acid concentrations did not have a significant effect on the rate of nickel extraction or the total amount of nickel extracted. The rate of copper removal was not significantly influenced by the initial copper concentration, but copper removal was affected by the initial acid concentration. In oxidative tests with high initial acid concentrations, the rate at which copper was leached from the matte was faster than the rate of cementation. The results suggest that operating under high initial acid conditions could interfere with copper removal with no significant benefit in terms of nickel extraction. The results allow the regression of rate expressions.