Use of the flash-reactor principle to recover zinc from steel-mill dusts

Owing to legal restrictions, the disposal of residues, particularly of dusts, is becoming a serious problem. Finding suitable processes for the treatment of Zn-, Pb-, Ni-, Fe-, Cr-, Cl- and F-containing dusts lies at the core of the problem, and both ecological and economic considerations play an important role. These factors make the development of a suitable recycling process that functions within required parameters and that is feasible at an industrial level both a task and a challenge. In this article, a promising process for the recovery of zinc from steel-mill dusts is described. For more information, contact J. Antrekowitsch, University of Leoben, Department of Metallurgy/Nonferrous Metallurgy, Christian Doppler Laboratory for Secondary Metallurgy of Nonferrous Metals, A-8700 Leoben, Austria; +43-3842-402-5203; fax +43-3842-402-5202; e-mail antreko@unileoben.ac.at.     

Iron control in zinc pressure leach processes

The occurrence of zinc in sulfide ore deposits is generally accompanied by various iron minerals. Hence, even the most efficient concentrators generally produce a zinc concentrate with significant iron content. The efficient recovery of zinc metal from zinc concentrates requires the rejection of iron residue in a form that minimizes the zinc entrainment. Careful control of the iron precipitation step is important, so that the iron residue produced is amenable to efficient liquid-solid separation in order to obtain high zinc recoveries. In hydrometallurgical zinc processes, the coprecipitation of minor impurities along with iron precipitation is also important in producing zinc-sulfate solution from which high-purity zinc cathode can be electrowon. The integration of Dynatec’s zinc pressure leach process with existing roast-leach-electrowin plants employing various methods of iron rejection is briefly described in this article, along with the application of two-stage pressure leaching in stand-alone processes. For more information, contact W.D. Vardill, Dynatec Corporation, 8301-113 Street, Fort Saskatchewan, Alberta, Canada T8L 4K7; (780) 992-8190; fax (780) 992-8100; e-mail wvardill@mettech.dynatec.ca.     

Recovering metals from red mud by thermal treatment and magnetic separation

This paper deals with an alternative treatment for recovering metals from goethite red mud (RM), which occurs as a by-product at zinc leaching plants. It is derived from the hydrometallurgical treatment of sphalerite, which involves roasting followed by acid attack and subsequent recovery of the zinc by electrodeposition. The leaching mud contains various oxides and hydroxides of iron plus lesser amounts of sulfates of Pb, Zn, Ca, Cd, Ag, In, Se, and other metals. In recent years, numerous attempts have been made to recover the RM or render it inert, particularly by such processes as vitrification or lithification for the production of glass ceramics. The work reported here proposes a treatment involving reduction and magnetic separation to permit the extraction of pure zinc, a high percentage of a pure magnetite, and a harmless slag containing mixed silicates of zinc and lead as well as oxides of minor elements.     

高压酸浸镍钼矿提取钼和镍

研究一项针对镍钼矿用高压酸浸的方法回收镍和钼的全湿法工艺。采用该工艺避免了传统上艺焙烧镍钼矿（15％～25％s）带来的人量S02和As2O3排放,减小了对环境的污染;与现有的湿法碱浸回收钼工艺相比,本工艺存酸浸过程中回收了儿乎全部的镍和人部分的钼。在氧压环境下,几乎全部的镍和大部分的钼都进入溶液,少部分的钼留在酸浸渣中,睃浸渣进一步用碱（NaOH）浸出。在最佳的实验条件下,97％的镍和96％的钼分别被浸出。     

Iron extraction from lead slag by bath smelting

A new bath smelting process was proposed to recover iron for solid wastes reduction. 99.79% of iron metallization, 99.61% of iron recovery, pig iron with 93.58% Fe, 0.021% S, 0.11% P, 1.38% C, 0.22% Si, 0.01% Pb and 0.031% Zn were achieved after the wastes were smelted at 1575 °C for 20 min under C/Fe molar ratio of 1.6 and basicity of 1.2. The produced pig iron could be used in steel-making. This study provides a way for recycling iron from smelting slag and hydrometallurgical residue.     

Recovery of valuable metals from zinc leaching residue by sulfate roasting and water leaching

Zinc leaching residue (ZLR), produced from traditional zinc hydrometallurgy process, is not only a hazardous waste but also a potential valuable solid. The combination of sulfate roasting and water leaching was employed to recover the valuable metals from ZLR. The ZLR was initially roasted with ferric sulfate at 640 °C for 1 h with ferric sulfate/zinc ferrite mole ratio of 1.2. In this process, the valuable metals were efficiently transformed into water soluble sulfate, while iron remains as ferric oxide. Thereafter, water leaching was conducted to extract the valuable metals sulfate for recovery. The recovery rates of zinc, manganese, copper, cadmium and iron were 92.4%, 93.3%, 99.3%, 91.4% and 1.1%, respectively. A leaching toxicity test for ZLR was performed after water leaching. The results indicated that the final residue was effectively detoxified and all of the heavy metal leaching concentrations were under the allowable limit.     

Effect of Cu~(2+)ions on bioleaching of marmatite

The effect of Cu~(2+)ions on bioleaching of marmatite was investigated through shake leaching experiments.The bacteria inoculated are a mixed culture ofAcidithiobacillus ferrooxidans,Acidithiobacillus thiooxidans and Lepthospirillum ferrooxidans.The results show that zinc is selectively leached,and the addition of appropriate content of Cu~(2+)ions has positive effect on the bioleaching of marmatite.SEM and EDX analyses of the leaching residue reveal that a product layer composed of iron sulfide, element...     

Extraction of indium from indium-zinc concentrates

1Introduction The typically traditional process for extracting indium from In-Zn concentrates includes the following steps.Firstly,ferric is removed by the method of jarosite,and indium goes into jarosite residues[1?4].In order to recovery indium from the…     

Identifying nanoscale ferrihydrite in Hydrometallurgical residues

The identification of a disordered nanoscale material such as ferrihydrite in a heterogeneous sample environment, as is typically the case in a hydrometallurgical residue, requires a rigorous multifaceted characterization approach. An example of this is the identification of ferrihydrite in paragoethite process residues generated in zinc refining. In a pure-form ferrihydrite, a poorly crystalline iron(III) oxyhydroxide possesses a characteristic powder x-ray diffraction profile consisting of very broad low-intensity reflections. However, in coexistence with crystalline material, the diffraction profile may be masked, lost in the background noise, and easily overlooked. By using several characterization approaches in combination, ferrihydrite can be identified in a hydrometallurgical residue with a higher degree of confidence than can be achieved by the application of a single technique.     

Recovering in,Ge and Ga from zinc residues

A novel solvent extraction process has been developed to selectively recover indium, germanium and gallium from the cement residue sulfuric acid leach solutions in a hydrometallurgical zinc plant. The key work was to determine a special organic molecule for gallium and germanium extraction. Continuous countercurrent tests on the mini-pilot plant level were performed successfully with 90.7%, 94.2% and 92.9% yield from cement residue to metals, for indium, gallium and germanium, respectively.     

Recovery of scandium from bauxite residue——red mud:a review

Red mud is a slimy caustic residue generated from alumina production. Taking into account the relatively considerable content and availability of scandium, red mud can be viewed as an important and promising scandium resource rather than a solid waste. This paper is primarily to review the investigations of scandium recovery from red mud based on the most widely used hydrometallurgical processes including acid leaching, solvent extraction and ion exchange adsorption. It is thought that recovery of scandium from red mud should be considered as a direct objective rather than a by-product in the development of overall flowsheet. In order to achieve environmentally-friendly processes with high scandium recovery and low cost, more attention is required to be paid to optimizing the selective leaching of scandium to decrease mineral acid consumption and alleviate pollution, and developing new solvent extraction systems and novel ion exchange adsorption materials with high selectivity and recognition for scandium.     

Hydrometallurgically treating antimony-bearing industrial wastes

In many instances, by-products or wastes containing antimony are generated during metallurgical processes. Although these materials pose environmental, recycling, and marketing challenges worldwide, the use of antimony hydrometallurgical leaching principles and technologies may provide a remedy. This paper outlines techniques for treating antimony-containing wastes and offers examples of applications for those wastes and by-products. For more information, contact C.G. Anderson, Montana Tech of the University of Montana, the Center for Advanced Mineral and Metallurgical Processing, Room 221 ELC Building, Butte, Montana 59701; telephone/fax (406) 496-4794; e-mail: CAnderson@mtech.edu.     

锌湿法冶金工艺概述

介绍现有硫化锌精矿焙烧-浸出、硫化锌精矿直接浸出、氧化锌矿和氧化锌烟尘直接酸浸出三大湿法冶金工艺及其它炼锌工艺的不同方法,并比较分析其优缺点。     

Recovery of zinc and lead from Yahyali non-sulphide flotation tailing by sequential acidic and sodium hydroxide leaching in the presence of potassium sodium tartrate

The recovery of zinc and lead from Yahyali non-sulphide flotation tailing using sulfuric acid followed by sodium hydroxide leaching in the presence of potassium sodium tartrate was experimentally investigated. In the acidic leaching stage, the effects of pH, solid-to-liquid ratio and temperature on the dissolution of zinc from the tailing were explored. 82.3% Zn dissolution was achieved at a pH of 2, a temperature of 40 °C, a solid-to-liquid ratio of 20% and a leaching time of 2 h, whereas the iron and lead dissolutions were determined to be less than 0.5%. The sulfuric acid consumption was found to be 110.6 kg/t (dry tailing). The leaching temperature had no beneficial effect on the dissolution of zinc from the tailing. The acidic leach solution was subjected to an electrowinning test. The cathode product consisted of 99.8% Zn and 0.15% Fe. In the alkaline leaching stage, the Pb dissolution increased slightly in the presence of potassium sodium tartrate. More than 60% of Pb was taken into the leach solution when the leaching temperature increased from 40 to 80 °C. The final leach residue was analyzed by XRD and XRF. The XRD results indicated that the major peaks originated from the goethite and quartz while minor peaks stem from smithsonite and cerussite. The XRF analysis demonstrated that the residue contained 70.3% iron oxide. Based on the sequential leaching experiments, the zinc and lead were excellently depleted from the flotation tailing, leaving a considerable amount of iron in the final residue.     

氧压酸浸处理锌焙砂中浸渣的新工艺研究

锌焙砂一般采用中性-低酸-高酸三段浸出工序,该工艺在酸浸出中浸渣的过程中,铁也大量浸出进入到溶液中,加重了净化电积前除铁的负担。通过将传统锌湿法冶金工艺与氧压酸浸新工艺相结合,研究了氧压酸浸处理中浸渣的氧气压力、硫酸浓度、温度、浸出时间、粒度、液固比和分散剂等相关因素的影响。实验结果表明该工艺不仅提高了锌的浸出率（〉98％）,降低了铁的浸出率（〈50％）,缩短了生产周期,降低了生产成本,具有良好的经济效益;而且还具有环境友好和资源利用率高等优点,实现了简化工艺和节能减排的目的,为工业化生产提供了参考．     

焙烧氰化尾渣中金、银和铁的回收利用研究进展

焙烧氰化尾渣是黄金生产排放的一类危险固体废物,其中的金、银和铁等有价金属元素仍可作为二次资源利用。系统总结了国内外在回收焙烧氰化尾渣中金、银和铁的研究进展,分析了磁化焙烧法、硫脲浸出法、氯化浸出法、高温氯化焙烧法、强酸预浸-氰化浸出法、直接还原焙烧法和细磨法在资源综合回收利用中的优缺点,指出焙烧氰化尾渣的资源化、减量化和无害化的发展方向。     

RECOVERY OF CADMIUM AND NICKEL FROM SCRAP Ni-Cd BATTERIES

1. Introduction Portable electricity has become a part of daily living. Batteries literally empower many kinds of portable electric and electronic devices, such as telephones, computers, radios, compact disks, tape recorders, cordless tools, and even electric cars. But at end-of-life they can come back to haunt us. Now, how to handle the niillion-tons of scrap Ni-Cd batteries is a big problem to all the countries[111]. 2. Ni-Cd Battery Applications and Effects on the Environment Profess…     

硫化锌银精矿富集银的工艺研究

基于国内外硫化锌矿处理的火、湿法研究进展,对含锌银精矿采用硫酸化焙烧、稀硫酸浸出工艺脱除锌、富集银,考察了焙烧和浸出过程中的主要影响因素。结果表明,硫酸配比为150%,在300℃焙烧90 min,以5%稀硫酸为浸出剂,液固比8:1,搅拌转速200~300 r/min,85℃浸出120 min,最终锌的浸出率可达到98%以上,浸出渣中银含量为7.24%,银被富集7倍。     

不锈钢粉尘的粒度与元素分布对回收利用的影响

本研究对不锈钢粉尘粒度作了分析,并对不同粒度的不锈钢粉尘进行分组,按照不锈钢粉尘的粒度大小进行观察和分析。其中采用X射线能谱4E（EDS）分析了不锈钢粉尘的形貌、元素组成。结果表明不锈钢粉尘中较大颗粒较多,而且不锈钢粉尘中的颗粒均为多个细小粉尘颗粒的聚合物。不锈钢粉尘中较大颗粒中含有的铁元素较多,而粒径较小的颗粒中含有的cr和Ni较多,若作为不锈钢回收利用,可将不锈钢粉尘筛分之后,采用粒度较小的不锈钢粉尘作为原料。本研究结果可为不锈钢电弧炉粉的处理及综合利用提供数据。     

Processing of Zinc Oxide Fume at Flin Flon,Manitoba

The hydrometallurgical processing of an impure zinc oxide fume is described. Flowsheet includes roasting for fluorine elimination and countercurrent leaching to produce a neutral sulphate solution. This solution is combined with zinc sulphide leach solution for subsequent purification and electrolysis. Novel to the neutral leach step is the use of automatic pH control.