Determining silica solubility in bayer process liquor

The efficient precipitation of dissolved silica from Bayer process liquor is essential for the production of high-quality alumina and the reduction of excessive scaling in the heat exchangers in the evaporation building of Bayer processes. The accurate prediction of silica solubility in Bayer liquor is one of the key parameters in improving the design and operation of the desilication process. Previous findings, particularly with respect to the influence of temperature and concentrations of caustic soda and alumina on the solubility of silica, are inconclusive. In this article, experimental results are presented over a wide range of temperature and alumina and caustic soda concentrations. Attempts are made to utilize artificial neural networks for identifying the process variables and modeling. The radial basis function neural network architecture was used successfully to generate a nonlinear correlation for the prediction of the solubility of silica in Bayer process liquor. The resulting correlation can predict the present data and the control data of other investigators with good accuracy. M. Jamialahmadi earned his Ph.D. in chemical engineering at Aston University in 1983. He is currently a professor and dean of the Petroleum Industry Research Center, Ahwar, Iran. H. Müller-Steinhagen is currently a professor and head of the School of Engineering in the Environment, University of Surrey.     

拜耳液中铁的行为研究

本文对拜耳液中铁的行为进行了研究.考察了保温时间、过滤温度、过滤介质和铝土矿中的硫对拜耳液铁含量的影响;铝土矿中硫含量高是引起拜耳液中铁含量高的主要原因;对含Na2S的碱液中的铁化合物进行了粒度和ze协电位的测定,证明了胶体态铁化合物的存在.     

Recovering gold from copper concentrate via the HydroCopper™ process

HydroCopper? technology comprises a chloride-leaching method for copper sulfide concentrates and copper production up to semi-products. As compared with the commonly used sulfate solutions, brine solutions offer aggressiveness and stability of the copper(I) ion and, consequently, a lower energy consumption in leaching. Copper(II) ions and oxygen are used as oxidants. Iron reports to the leaching residue as oxide and sulfur as elemental sulfur. Gold is dissolved and recovered in the third stage of the counter-current leaching when the redox potential reaches higher levels.     

The cuprex metal extraction process: Recovering copper from sulfide ores

The Cuprex? metal extraction process produces cathode-grade copper using a hydrometallurgical process based on chloride leaching of sulfide ore concentrates. The process incorporates several novel steps to overcome the major problems associated with earlier chloride-based processes, including mild leaching conditions using ferric chloride as leachant and solvent extraction of copper usinga novel reagent. This produces a highly concentrated cupric chloride electrolyte from which cathode-grade copper is electrowon in the Metclor cell. The technical viability and robustness of the core technology have been proven in a series of large-scale pilot trials. More recent work has concentrated on supplementary processes to convert the copper powder product to an article of commerce and to recover valuable by-products. A fully integrated scheme is now being developed with updated cost estimates.     

联合法提镓工艺研究

针对联合法氧化铝厂循环母液含镓的特点 ,提出采用化学法和树脂吸附法相结合的方式从烧结法拜耳法循环母液回收镓的新工艺 ,并通过小试和扩大试结果分析 ,从技术和经济诸方面阐述了该工艺的可行性     

Recovering lead from batteries

Over the past 20 years, a significant number of processes have been developed to recover lead from scrap batteries. These processes recover lead via hydrometallurgical processing of the paste component of the battery followed by electrowinning. A number of pilot plant operations have been conducted, but thus far none of the processes have become operational.     

Recovering metals from hydrometallurgical residues

Experimental results and a method for recovering Cu, Zn, Cd, and Co from a solid hydrometallurgical residue are presented. A series of leaching, oxidation, and solvent extraction stages are the keys to the process.     

常压混合脱硅工艺生产种分精液

本文介绍了碳分、种分工艺对精液硅量指数A/S的不同要求,认为种分精液单独生产是很有必要的.本文从理论上分析了目前所应用的脱硅工艺,提出了一种常压生产种分精液的方法-常压混合脱硅工艺,并对某厂采用此工艺进行种分精液生产的情况进行了简单的介绍.     

高铝粉煤灰生产氧化铝过程中镓提取工艺研究

鉴于粉煤灰潜在的应用价值,粉煤灰循环再利用为兼顾经济和环保效益提供了绝佳的机会。本文全面的阐述了从预脱硅碱石灰烧结法生产氧化铝过程中提取镓的生产工艺。采用螯合离子交换树脂从铝浓度较高的种分母液中选择性分离低含量的镓,并对吸附数据进行了玻尔兹曼分布拟合及分析。文中还对工艺中孔蚀问题和玻璃鳞片的防腐性能进行了研究。     

Recovering Silver from Photographic Process Wastes

Spent color bleach-fix solution (CBFS), a product of photographic processing operations, is a potential source of silver. Of the extraction reactors used in recovering this silver, the rotating cylindrical electrode (RCE) has an advantage in that it provides improved mass transfer with an extended effective surface area. In addition, the application of a potentiostatic technique allows the silver deposition reaction to take place preferentially, without the formation of silver sulfide. The process consists of prior physical treatment, subsequent chemical reduction of the ferric-EDTA (ethylene diamine tetra-acetic acid) complex present in the CBFS with sodium dithionite (monitored by measuring the redox potential of Fe³⁺/Fe²⁺ couple), followed by electrodeposition of silver in a divided cell using a cation exchange membrane. The combined procedure results in increased current efficiency and reduced electrolysis time.     

Recovering flake graphite from steelmaking kish

As part of its research efforts to encourage conservation and reuse of natural resources, the U.S. Bureau of Mines has developed a process to produce high-quality flake graphite from the steelmaking waste known as kish. The kish produced by current steelmaking practices is a mixture of graphite, desulfurization slag, and iron that is skimmed from the molten iron feed to the basic oxygen furnace. Kish was treated by a combination of screening and hydraulic classification to produce a concentrate containing more than 70% graphite. Acid leaching of the concentrate gave a graphite product with 95–99% purity and a flake size ranging from 10 mesh down. Industrial graphite users indicated that kish graphite is a suitable substitute for natural graphite material for most uses.     

Recovering recyclable materials from shredder residue

Each year, about 11 million tons of metals are recovered in the United States from about 10 million discarded automobiles. The recovered metals account for about 75 percent of the total weight of the discarded vehicles. The balance of the material, known as shredder residue, amounts to about three million tons annually and is currently landfilled. The residue contains a diversity of potentially recyclable materials, including polyurethane foams, iron oxides, and certain thermoplastics. This article discusses a process under development at Argonne National Laboratory to separate and recover the recyclable materials from this waste stream. The process consists essentially of two stages. First, a physical separation is used to recover the foams and the metal oxides, followed by a chemical process to extract certain thermoplastics. The status of the technology and the process economics are reviewed here.     

Recovering selenium from copper refinery slimes

The selenium contained within copper refinery slimes may be recovered advantageously by roasting at about 600°C. While roasting in air is inefficient, roasting in a sulfating atmosphere enables practically complete selenium recovery. Based on laboratory tests, a new selenium recovery process was adopted at Outokumpu Copper Refinery. In this process, sulfation is achieved by feeding sulfur dioxide and oxygen into the roasting furnace.     

Recovering precious metals from electronic scrap

This article characterizes electronic scrap in terms of origin and composition and describes the steps in preliminary processing: sorting, calcination, combustion, shredding, and sampling. Hydrometallurgical and pyrometallurgical process technologies for the concentration and recovery of precious-metals values in scrap are reviewed, and some downstream processing options are outlined. The article concludes with some caveats concerning the risky but potentially profitable business of recovery of precious metals from electronic scrap.     

Recovering cobalt from secondary sources in India

In the latter half of this decade, the demand for cobalt in India has increased sharply—from 55 tonnes in 1995 to more than 500 tonnes in 1998. As India does not have domestic cobalt feedstock sufficient to meet most of this demand, it imports and processes considerable secondary cobalt resources. To most effectively deal with these secondary materials, Indian laboratories have developed a variety of customized approaches for recovering cobalt values. Radhanath P. Das earned his Ph.D. in metallurgy at the Pennsylvania State University in 1974. He is currently head of the hydrometallurgy and electrometallurgy division at Regional Research Laboratory in Bhubaneswar, India.     

Recovering cobalt from primary and secondary sources

Cobalt is designated as a minor metal in the marketplace. Apart from a few exceptions, it is produced as a by-product of either nickel or copper and is used in a wide range of specialist applications. This article outlines a number of the processes used for extracting cobalt from nickel and copper ores and highlights the differences in terms of chemical composition and physical form in the cobalt produced. The suitability of the different types of cobalt for particular end-use applications is discussed, as are some of the techniques utilized in industry to allow greater flexibility in the choice of cobalt. M.J. Hawkins earned his Ph.D. in physical metallurgy in 1973. He is currently general manager at the Cobalt Development Institute. Dr. Hawkins is a member of TMS.     

从氧化锌矿浸出渣中回收锌

低品位氧化锌矿酸浸后,浸出渣中夹带3%以上的锌,采用水洗-P204萃取可回收酸浸渣中的水溶性锌,得到的反萃液经过净化后可电积沉锌.该工艺可与湿法炼锌工艺相结合处理低品位氧化锌矿.     

从氧化锌矿浸出渣中回收锌

低品位氧化锌矿酸浸后,浸出渣中夹带3％以上的锌,采用水洗-P204萃取可回收酸浸渣中的水溶性锌,得到的反萃液经过净化后可电积沉锌。该工艺可与湿法炼锌工艺相结合处理低品位氧化锌矿。