Hydrometallurgical processing of Platreef flotation concentrate

Platinum producers are evaluating hydrometallurgical process routes to extract platinum group metals (PGM) and base metals (BM) from flotation concentrate that are alternative to conventional pyrometallurgical matte smelting treatment of flotation concentrates. This approach would attract several potential benefits to the cost-effective processing of lower-grade and high-chromium concentrates. Ivanhoe Nickel and Platinum Ltd. wished to investigate this option on samples arising from their Platreef project in the northern limb of the Bushveld Complex in South Africa, from concentrate containing 1.5 g/t Pt, 2.5 g/t Pd and 0.5 g/t Au, as well as 1.5% Ni and 1.2% Cu. Other PGMs assayed rather low grades in the concentrate (Rh 128 ppb; Ru 153 ppb; Os 18 ppb; Ir 31 ppb) so the focus was on Pt, Pd and Au in this study. Some twenty-two hydrometallurgical process flowsheet variants were considered for evaluation in a testwork programme combining several conventional and proprietary unit process technologies.The testwork outcomes suggested that a hydrometallurgical flowsheet alternative to smelting (the patented Kell Process) is potentially a practical, environmentally benign and energy-efficient approach for treating low-grade Platreef concentrate with relatively low risk. This process broadly comprises selective leaching of base metals by pressure oxidation, followed by leaching of PGMs after a roasting pretreatment step shown to render PGMs and particularly Pt amenable to leaching. The process embodies separation of the value metals (PGM and base metals) into separate chloride and sulfate solution streams, respectively, and impurity elements (Fe, Al and gangue) into a tailings product. Key elemental deportments from the un-optimized process were Ni 96%, Co 94%, Cu 94%, Pt 96%, Pd 94% and Au 87%.Preliminary work indicated that further improvements in value metal recoveries, impurity separations and reagent consumptions may be gained from further optimization of the individual unit processes. Moreover, the recycle of key reagents uses existing proven technologies, rendering the process more economically and environmentally favourable. Initial assessment suggests that the Kell Process should offer both economic and environmental benefits over conventional pyrometallurgical matte smelting treatment of Platreef flotation concentrate.     

从热滤渣中富集贵金属的实验研究

针对含贵金属热滤渣物料的物相及元素组成, 提出了氧化焙烧脱硫-硫酸选择性浸出贱金属铜和镍富集贵金属工艺, 讨论了物料粒度、焙烧时间、焙烧温度、硫酸浓度、浸出时间、浸出温度等因素对贵金属富集比的影响。获得最佳工艺参数为: 热滤渣粒度0.080~0.106 mm, 焙烧时间6 h, 焙烧温度700 ℃, 硫酸浓度45%, 浸出时间5 h, 浸出温度95 ℃。在此条件下, 脱硫率达到98.89%, 铜、镍浸出率分别为98.33%和98.12%, 硫酸浸出渣中Au含量1 198.60 g/t, Ag含量1 807.79 g/t, Pt含量1 801.27 g/t, Pd含量1 937.66 g/t。从原料到硫酸浸出渣, 贵金属富集比达到14.19倍。该工艺流程操作简单、富集比高、回收率高、成本低, 可为从热渣中富集贵金属提供借鉴作用。     

Microwave caustic leaching of electric arc furnace dust

Electric arc furnace (EAF) dust is a waste product which is generated when steel scrap is melted in an electric arc furnace. It contains high concentrations of iron, zinc and lead. Numerous pyrometallurgical and hydrometallurgical processes have been developed to treat this material. Only a limited number of these have reached commercialization and the majority have been pyrometallurgical. However, the hydrometallurgical processes, such as caustic leaching, offer some potential advantages.In the present research, the application of microwave radiation at 2.45 GHz was employed, as the energy source, in the hydrometallurgical caustic leaching process for EAF dust treatment. The variables which were investigated were: leaching time, microwave power, caustic concentration and the solid to liquid ratio. The experimental results showed that the zinc recovery from the dust increased with a decrease in the solid to liquid ratio and an increase in the microwave power. The optimum caustic concentration for the maximum zinc recovery was 8M. The rates of zinc recovery were significantly higher under microwave conditions as compared to those observed with conventional leaching. Some possible mechanisms to explain this behaviour are discussed.     

加压氧化浸出处理硫化砷渣

回顾了一些处理硫化砷渣的湿法冶金工艺，介绍了硫酸铜置换和硫酸高铁浸出工艺。文中详述了北京矿冶研究总院开发的加压氧化浸出处理硫化砷渣的新工艺，给出了工艺参数和试验结果。与其他工艺相比，加压氧化浸出法具有流程短、砷浸出率高、浸出时间短等优点     

矿浆电解法处理铜镍高冰镍

介绍了一种钢镍高冰镍湿法处理新方法。采用矿浆电解技术直接浸出电解高冰镍矿浆,产出海绵铜和硫酸镍溶液,贵金属保留在浸出终渣中,使有价金属得到有效分离和提取。该方法具有流程简单、金属回收率高、成本低等优点。     

Direct leach approaches to Platinum Group Metal (PGM) ores and concentrates: A review

Platinum Group Metals (PGMs), often with associated gold, have very few occurrences where they are present in an ore deposit at economically extractable levels. They are classified as both precious and critical metals due to their scarcity and their wide industrial use. With deteriorating socio-political environments in most primary PGM producing countries, PGM deposits that are smaller but in less risky jurisdictions have to be evaluated. However, the lower PGM grades, increased mineralogical complexity of the ores, capital intensity and strict environmental regulations in other international jurisdictions, limit the implementation of conventional metallurgical processing options, particularly smelter-based operations. The conventional smelter-based process options are justifiable for high grade, low chromite, large resource and long life-of-mine operations.In the present paper, we review some of the most recent literature on the predominantly hydrometallurgical approaches to PGM extraction. A number of metallurgical processes that generate either a PGM rich leachate or a residue containing metal values, and the various methods in use for their recoveries from pregnant rich solutions are reviewed. Sixteen process flowsheet variants combining conventional and proprietary unit process technologies are provided, and their process chemistries and key technical operating parameters are compared. Where appropriate, the key thermodynamic and kinetic factors are given and compared.     

The effect of flotation and parameters for bioleaching of printed circuit boards

Waste electrical and electronic equipment (WEEE) is currently one of the fastest growing waste streams in the world. Typical for WEEE is the high content of valuable and precious metals, as well as harmful contaminants like halogens, flame retardant chemicals and plastics. Currently, WEEE treatment and metal recovery methods are imperfect, polluting and energy intensive. In this paper, novel treatment possibilities are outlined for printed circuit boards (PCB) utilizing both the flotation separation technique and acid bioleaching. Flotation, conducted after crushing and sieving of PCB, produced two fractions: metal-rich concentrate, which is more suitable for pyrometallurgical treatment than untreated PCB, and metal-poor froth suitable for acid bioleaching. It was seen that especially low pH (1.6), high initial Fe²⁺ concentration (7.8 g/l) and low PCB froth concentration in the bioleaching solution (50 g/l) were beneficial for the rapid and selective dissolution of copper. With these parameters, 99% of copper was solubilized from PCB froth in bioreactor treatment, with Cu (6.8 g/l) and Fe (7.0 g/l) being the only major metallic elements in bioleaching solution.     

铅阳极泥湿法预处理综合回收新工艺

研究铅阳极泥湿法预处理综合回收新工艺：铅阳极泥经过自然堆放氧化后,在硫酸介质中控电位氧化氯化浸出,能有效地实现贵金属与非贵金属的分离。浸出液经过冷却结晶,析出部分砷,其他有价元素留在溶液中。后通过控电位的方法还原沉碲,碲的回收率为96.52%。将沉碲后液依次进行水解沉锑、铁粉还原沉铋铜,锑、铋、砷的回收率均大于91%。该工艺流程简单,无废气产生,中间产物渣不产生堆放污染,可直接进入株冶原有火法系统进一步精炼回收有价金属,终端还原后液可循环使用。     

红土镍矿酸浸沉镍后液中镁资源化的研究进展

红土镍矿的加压酸浸、常压酸浸、堆浸工艺分别适用于褐铁矿型红土镍矿、过渡层和硅镁镍矿型红土镍矿,两种或两种以上的湿法联合处理工艺对矿石适用范围更广。在红土镍矿酸浸过程中,Mg和Ni、Co等同时被不同程度的浸出进入溶液,浸出液沉淀富集Ni、Co后产生大量的含镁废水。若不对其进行有价回收,不仅造成了资源的浪费,还会污染环境。本文综述了红土镍矿酸浸沉镍后液中Mg资源化工艺的研究进展及工业化情况,其中包括沉镍后液中Mn(II)的净化,并对今后的研究发展方向进行了展望,以期为红土镍矿中Mg的综合回收提供技术参考。     

湿法冶金过程中除铁工艺研究进展

除铁是湿法冶金过程的关键工序.铁杂质的去除,不仅可以提高产物的品位,而且有利于实现铁元素的回收利用.文章综述了湿法冶金中几种典型的湿法除铁的工艺,并将其分为浸出法(直接浸出、焙烧-浸出)、沉淀法(氧化沉淀、磷酸盐沉淀、水热水解赤铁矿、FeSx-CuS共沉淀法)、萃取法和离子交换法四大类,分析了不同工艺的原理、过程及优缺点,提出了湿法沉铁的发展方向.     

The use of ion exchange resins for the treatment of cyanidation tailings part 1––process development of selective base metal elution

This work investigates the use of oxidative acid eluents for the elution of base metals from strong base ion exchange resins. Eluents composed of a mixture of H₂O₂ and H₂SO₄ were tested for eluting base metals from resins loaded with mixtures of base and precious metal cyanides. This process removed 100% of Cu and Zn loaded on the resin, without affecting the precious metal loading. It was found that copper could be removed separately from the other base metals. The elution technique was not effective for removing iron from the resin. Cyanide associated with base metals was recovered as NaCN. Some oxidation of cyanide was noticed, subject to the elution conditions.This oxidative acid elution process could be used in commercial operations for the selective elution of base metals from a strong base ion exchange resin bed operating in alternative adsorption/base metal elution cycles. Thus, virtually all metal cyanide species could be recovered from cyanide leached solutions or slurries to give relatively clean tailings without compromising precious metal recovery efficiency. The process also caters for cyanide recovery and recycling.     

Operation of the Las Cruces ferric sulphate leach pilot plant

As part of the Feasibility Study for the Las Cruces copper deposit, Rio Tinto Technology carried out an in-depth evaluation of two hydrometallurgical processes. The two options examined were mild pressure leaching and atmospheric ferric sulphate leaching. Both were proved technically viable at pilot plant scale. The atmospheric ferric leach pilot plant was designed, constructed and operated by Rio Tinto Research & Technology Development (R&TD), Melbourne in order to evaluate areas of technical uncertainty, to generate process design data and establish the department of elements in the various process streams. This paper provides a review of the pilot plant operation and presents some of the results generated from this work.     

Recovery of heavy metals from MSW molten fly ash by carrier-in-pulp method: Fe powder as carrier

Municipal solid waste (MSW) molten fly ash is classified as a hazardous waste because it contains considerable amount of heavy metals, which pose environmental concern due to their leaching potential in landfill environment. This study proposes carrier-in-pulp (CIP) method as a new hydrometallurgical route to extract and recover Pb, Zn, Cu, and Cd from molten fly ash before landfilling. In this method, a carrier material, which recovers the extracted metals, is added simultaneously with fly ash to a leaching solution and is harvested from the pulp by physical separation method, such as magnetic separation or sieving.To demonstrate the effect of the CIP method, shaking flask experiments were conducted under various conditions using NaCl solution, iron powder as carrier, and molten fly ash. More than 99 wt% Pb, Zn, and Cd, and 97 wt% Cu were extracted from the ash. However, only Pb and Cu were recovered (96.3 wt% Pb and 94.3 wt% Cu) by the iron powder through cementation, leaving behind Zn and Cd ions in the solution phase. The leaching test conducted on the treated fly ash residue revealed that the CIP method suppressed the solubilization of Pb to a value below the landfill disposal guideline.     

辉钼精矿加压湿法冶金技术研究进展

为了使辉钼精矿湿法冶金从业者对氧压煮法的认识更全面、更系统,从而促进氧压煮技术的发展,总结了国内外加压湿法冶金技术在辉钼精矿处理领域的研究进展,介绍了加压酸浸和加压碱浸技术从辉钼精矿中提取钼的物化原理、工艺流程和生产实践概况,指出了不同加压浸出工艺的优缺点。高温高压下酸浸辉钼精矿常以硝酸盐或硝酸作催化剂,具有反应速度快、投资效益大、钼转化率高等特点,但存在设备腐蚀严重、难以精确控制反应条件以及氮氧化物污染等问题;与加压酸浸相比,加压碱浸工艺具有金属回收率高、反应介质对设备腐蚀性小、反应温和、浸出液中杂质含量少等优势,然而,加压碱浸工艺存在氢氧化钠消耗量大、产生的大量硫酸钠较难处理等不足。通过对现有氧压浸出工艺的分析,指出了辉钼精矿加压湿法冶金技术发展需解决的问题和努力的方向。     

废旧锂电池正极材料中有价金属的回收工艺研究进展

随着新能源汽车、电子产品等产业的迅猛发展,其核心元件锂离子电池的需求量提升明显,但废旧锂离子电池带来的环境污染和资源浪费问题也日益严重。因此,对废旧锂离子电池的无害化处理和对其中稀缺的有价金属的有效回收利用已经成为国内外科研院所研究的热点及重点。本文综述了从废旧锂离子电池正极材料中提取有价金属的工艺:湿法回收工艺、火法焙烧-湿法冶金联合回收工艺、生物浸出回收工艺以及其他回收工艺。主要阐述了各种方法的原理及优缺点,指出了回收工艺的未来发展方向。      

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。     

Bio hydrometallurgical recovery of metals from Fine Shredder Residues

The leaching step of an integrated hydrometallurgical process for the selective recovery of metals from polymetallic concentrates has been investigated. This concentrate has been produced by physical treatment of Fine Shredder Residues derived from a shredding plant processing a mixed feed of metallic scraps, waste electric equipments and end-of-life vehicles. Bacterially assisted leaching experiments have been carried out using a copper-adapted consortium of mesophilic bacterial strains. The influence of various operating conditions such as stirring speed, temperature (25-50 °C), pulp solids density (5-20%) and initial iron concentration (0-15 g/L) has been studied. Temperature and stirring speed have proved to be the most influential parameter regarding copper dissolution kinetics, while pulp solids density and initial iron concentration have been found to have a subordinate importance. In optimum conditions, 95% extractions of zinc and copper were achieved within 48 h. Bacterial presence has been found beneficial in terms of catalysing copper dissolution.     

低冰镍加压酸浸工艺研究

本文研究了低冰镍湿法冶炼工艺流程,详细进行了低冰镍加压酸浸-萃取脱铜-中和除铁-中和沉镍的工艺研究。在优化试验条件下,加压浸出镍、铜的浸出率分别为91.56%,99.08%。浸出液经萃取脱铜-中和除铁-中和沉镍工艺使有价金属分别得到回收富集。     

从某富料分离碲和贵金属的试验研究

"富料"是铜阳极泥经分铜富集作用产生的一种富含碲和贵金属的混合物。本文提出了从富料中分离碲和贵金属,在几乎不氧化贵金属的前提下,有效地回收碲和贵金属的工艺方法。用Na2CO3与富料均匀混合,在300℃下焙烧7 h,然后在NaOH溶液中浸出碲,整个过程贵金属几乎不被氧化而留在渣中。在最佳条件下,碲浸出率达95.0%,从而为实现碲和贵金属有效回收打下基础。     

Extraction of precious metals from technogenic placers of primorye

Intensive development of gold placer deposits in the South Far East of Russia has produced numerous technogenic placers (concentration dump tailings) that contain fine free and bound gold and the platinum group metals. The secondary processing of these technogenic placers makes it possible to extract the whole set of precious metals from the concentration tailings.The authors have elaborated the low-waste technology of extraction of useful components using the methods of gravitation, magnetic and electromagnetic separation, hydrometallurgy, and extraction. Usually, precious metals are leached with cyanide solutions that significantly deteriorate the ecological situation. Instead of them we propose to use thiocarbamide, thiocyanate, and mixed thiocarbamide and thiocyanate solutions in the process of utilization of the technogenic placers. Introduction of thiocyanate ions into the thiocarbamide leaching solutions increases the indices of gold extraction into a leaching solution. Efficiency of the precious metal extraction into leaching solutions is 94 ,- 96 ,.Our investigations showed that liquid extraction of gold and silver from the leaching solutions permits the precious metals to be extracted with additional separation from admixtures and essential decrease of specific thiocarbamide consumption. Comparatively inexpensive tributyl phosphate and diphenyl thiourea that are manufactured in production quantities, are used as extragents.Utilization of the technogenic placers of Primorye will produce the raw material for repeated extraction of precious metals and will be favorable for the ecological situation in the populous districts of the region where the placers exist.