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By Nobuaki Sato

For decontamination of SO2 containing waste gases from industries such as ferrous and non-ferrous metal companies, desulfurization with hydrogen production by the reaction of Br2 and SO2 was proposed as bromine-sulfur (BS) process. In this process, SO2 is fixed as H2SO4 in the presence of Br2 and H2O forming H2SO4 and HBr. Then hydrogen is produced by the decomposition of HBr and Br2 as byproduct is recycled. The reaction of Br2, SO2 and H2O was found not to occur in liquid phase but to occur in vapor one. The production ratios of H2SO4 and HBr showed a maximum at temperatures around 60 oC. The highest production ratio was obtained at 70 oC with a mixing ratio of Br2:SO2:H2O=1:1:10. The experimental results were discussed with thermodynamic consideration.

Jan 1, 2006

By I. Barin, G. Eriksson, F. Sauert

Computer-aided calculations using data bases and program systems are more and more needed for the rational development and optirnization of high-temperature processes. The calculation of mass and energy fluxes between different process steps as well as the determination of the chemical equilibria will be discussed, giving examples from nonferrous metallurgy. The simulation of a waste-material treatment process including high-temperature combustion and gas-cleaning systems will also be demonstrated.

Jan 1, 1988

By Gavin K. W. Freeman

The efficient separation of cobalt from nickel is a fundamental objective in the refining of cobalt. Based on recent experience at the Corefco refinery in Fort Saskatchewan, the identification of a novel process for the selective precipitation of cobalt from aqueous ammonia leach liquors is described. The addition of calcium sulphate, CaSO4.2H2O (gypsum), to an aqueous solution containing cobalt(III) hexammine sulphate, [Co(NH3)6]2(SO4)3, will result in the precipitation of a sparingly soluble double salt having the stoichiometry, [Co(NH3)6]2(SO4)3.2CaSO4.xH2O, where x = 4 or 6. Leach residues, which may contain a significant quantity of cobalt associated with the cobalt calcium double salt, can be washed with process solutions that contain ammonium carbonate. After contact with ammonium carbonate, the cobalt is recovered into solution, while the calcium is re-precipitated as the insoluble carbonate. The simplicity of this elemental separation and its high selectivity for cobalt, as well as the demonstrated usefulness in improving cobalt recoveries, are the basis for the potential applications of this process.

Jan 1, 2003

By Kamal Adham

Hydrochloric acid is used as lixiviant in such hydrometallurgy processes as synthetic rutile production and nickel extraction. The intermediary metal chloride is normally roasted to release gaseous HCl and a solid metal oxide. A large amount of fuel is required for this thermal regeneration, mainly to vaporize the water content of the feed solution. To conserve fuel, some energy recovery from the off-gas is currently achieved, but the fuel costs can further be reduced by process optimization and energy recovery from the gaseous, aqueous and solid products of the regenerator. Here, first the existing limitations to fuel efficiency in the industrial scale HCl regeneration roasters are described. Then, for the case of a dilute feed solution, options for pre-evaporation and fuel minimization are modeled and compared. Finally, energy recovery technologies including heat pumps, acid heat exchangers and solid waste heat boilers are described, and their potentials as the heat source for pre-evaporation of the feed are evaluated.

Jan 1, 2003

By Florian Kongoli

The overall productivity and efficiency of sulfide smelting plants depends considerably on the productivity and efficiency of each unit furnace operations. Furthermore, the efficiency and productivity of each furnace affects and dictates to a certain degree the process of managing the flow of materials from one unit to another. A furnace with low productivity, several technical problems or high frequency of accidental shut downs can easily become a temporary or a permanent bottle neck in the entire flowsheet and can be the cause for a low productivity and efficiency of the entire plant. As a result, controlling, optimizing and automating the individual furnace operations in order to assure a stable process but at the same time to increase productivity is an indispensable need. In this paper, the authors discuss their recent work in effectively controlling acute industrial furnace problems such as magnetite build-up and accretions, eliminating unnecessary slag foaming, decreasing slag losses etc. as well as the intensification, optimization and automation of a series of furnaces in sulfide smelting through a unique physical process modeling that correctly simulate the industrial furnace operations and avoid guessing and uncertainties. The advantages of this new approach have been discussed.

Jan 1, 2006

By P. G. West-Sells

Recovery of gold from thiosulfate leachates can be accomplished by adsorption of the gold thiosulfate complex by a strong base resin. Two of the most significant impurities that can decrease this gold adsorption are tetrathionate and trithionate, which are produced as oxidation products of thiosulfate during gold leaching. This paper investigates gold adsorption on a strong base resin (Purolite A500C) as a function of the concentration of these impurities. It is shown that concentrations of tetrathionate and trithionate as low as 150 mg/L can decrease gold loading by an order of magnitude, and that of the two ions, tetrathionate has a stronger detrimental effect. The resin and solution gold concentration profiles were successfully fit using a Freundlich isotherm, which further shows the strong effect of tetrathionate. To counteract the decrease in gold adsorption by tetrathionate, a novel process was proposed. Sulfite was added to the solution to oxidize tetrathionate to trithionate, and a nitrogen blanket was added to ensure that no further oxidation of thiosulfate could take place. It is shown that by incorporating this process, gold adsorption was doubled from both synthetic and real gold thiosulfate leachates.

Jan 1, 2003

By Leonard J. Friedman

There have been considerable changes in systems, equipment design and materials used in the modern Sulfuric Acid process. Many of these will shape the metallurgical sulfuric acid plant for the year 2000 and beyond. Advances have come from all over the world, and include new scrubbing area designs, catalyst contacting devices, silicon stainless alloys for unlined acid systems, energy recovery from acid heat, stainless converters and heat exchangers, etc. This paper describes each of the process "advances" and presents a review and analysis indicating advantages, operating experience and limitations.

Jan 1, 1988

By R. Menge, N. Basin, M. Sibony, J. Lecadet, S. Schmidt

In 1996, Metaleurop replaced its conventional sintering and blast furnace lead smelting activity in Nordenham, Germany by Sirosmelt/Ausmelt technology. Following some alterations to the process and the equipment, the bath smelting plant reached its design capacity for the treatment of lead concentrates, lead sulphate paste from spent batteries, secondaries and internal by-products. A reliable metallurgical process has been established, and thus higher process stability has been achieved, increasing simultaneously the refractory life. Nevertheless, improvements are needed to control the process with a better automation system and reliable expert-systems, because of the intensity of the smelting process. The introduction of the Sirosmelt process for the pyrometallurgical production of lead instead of the prior conventional process has also demonstrated the following advantages: reduced emissions of heavy metals and gaseous compounds, reduction of the specific energy consumption, minimization of residues and a reduction of staff and maintenance costs. The environmental performance of the plant meets the requirements of the German regulations.

Jan 1, 2000

By Robert W. Bartlett

Hazardous metal contaminants in liquid and solid wastes and from ground spills are important environmental problems in many metallurgical production operations. Acid rock drainage, from mines and huge quantities of permeable mine waste, is probably the most ubiquitous example. Fixing mine waste contaminants in situ has been practiced, using sulfate reducing bacteria (SRB) and organic reagents as electron donors to create anaerobic conditions and precipitate metal sulfides. Aqueous solutions of sugar and alcohol have been percolated into mine wastes with good results. However, maintaining anaerobic conditions permanently is unlikely, as these solutions are eventually washed out of solid waste and contaminated ground by inflow of either groundwater or meteoric water, allowing re-oxidation from entering air. Emulsions of inexpensive, non-aqueous organic microdroplets dispersed in water provide earth wettablility equal to aqueous solutions and easy percolation into both the ground and mine waste. Subsequent breakdown of the O/W emulsion provides permanent retention of the organic phase, attached to earth particles, that secures lasting anaerobic conditions, precipitates metals as sulfides and prevents re-oxidation of these sulfides. This process and its optimization are described, including experiments with sand-filled columns representing a vertical section through solid waste. Results of organic and metal retention in solid waste are provided from analyses of acid mine water drainage before and after waste treatment.

Jan 1, 2006

By Leszek Blacha

Since several years aog there is noted an increasing importance of the metallurgical vacuum technologies. This refers mainly to the extra furnace steel treatment processes, melting of steel and special alloys in the induction and arc vacuum furnaces, as well as refining processes of nonferrous metals. In the presented work, there is discussed a phenomenon of evaporation of volatile components of metal bath under reduced pressure with description of kinetics of this process. In this article are presented are the evaluation of the mass transfer coefficients in the melt and gaseous phase. Based on results of our own research on removal rate of impurities from liquid copper (bismuth, lead) in vacuum refining process, it is determined the thickness of hypothetical boundary layer in the gas phase. This allowed to formulate a general kinetic equation defining the evaporation rate of gaseous components from metal bath. The values of mass transfer coefficients determined from this equation were compared with experimental results by other authors working on the evaporation effect of melt components of metal alloys.

Jan 1, 2006

By D. G. C. Robertson

Counter-current staged reactors offer several advantages over batch reactors for mass transfer between two phases. Several metallurgical reactor designs have utilized the counter-current principle, e.g. the WORCA and QSL processes. But before the principle can be widely adopted, it will be necessary to overcome several significant problems. These include the need to minimize longitudinal mixing in a single reactor or to use several separate staged reactors and to carry out different reactions in sequence, e.g. phosphorus oxidation and sulfur reduction. Theoretical and experimental approaches to these problems will be discussed in the paper.

Jan 1, 1988

By David Langberg

Recovery of dissolved copper from discard slags is a critical consideration affecting the economics of copper smelting. Slag cleaning is frequently carried out in electric furnaces, however reduction by injection of natural gas in a holding furnace may offer a lower cost alternative in some circumstances. As the residence time of the injected gas is short, the factors controlling the rate of reduction need to be clarified in order to optimise the design of the slag cleaning furnace. A series of medium scale (200 kg) reduction tests to investigate the rate of reduction of copper-containing slags by injection of natural gas-nitrogen mixtures between 1150-1250C was carried out by CSIRO Minerals. The composition of the gas in the top-space of the reactor was found to be significantly more reducing than the slag, indicating that thermodynamic equilibrium was not established between the slag and the gas in the bubble plume. An apparent first order rate law was observed between the rate of oxygen elimination from the bath and the magnetite concentration of the bath. The dissolved copper concentration was closely correlated with the oxygen potential of the slag, suggesting a partial equilibrium between the dissolved components of the slag. The utilisation efficiency of the natural gas decreased as the natural gas flow rate was increased. The results of the tests tend to indicate that the rate is controlled by a mixed reaction kinetics/ mass transport mechanism. The work was supported by Xstrata Copper ? Mt Isa Mines.

Jan 1, 2006

By Wolfgang Baum

Remediation work on thermal process dusts and slags has been primarily based on chemical analyses. These data offer little information for the assessment of treatability and reuse potential. In addition, the lack of mineralogical residue characterization has frequently caused time-consuming and inefficient waste management. This paper will outline the cost-effective, and sucessful use of process-oriented mineralogical analyses for treatment and beneficial reuse of various thermal residues. These include a patented process for detoxification of Pb-contaminated bottom ash, the pyrometallurgical treatment of K 061, the reprocessing of lead smelter slag as well as various power plant residues.

Jan 1, 1992

By R. W. Lawrence

A high rate biological reduction technology has been developed to provide low cost hydrogen sulphide for various uses in water treatment and metallurgical processes. Commercial operations produce sulphide safely at a fraction of the cost of chemical sulphide. The biologically produced H2S is used for treatment of acid wastewater and selective metal recovery whereby metals present in wastewater streams are recovered in high grade metal sulphide concentrates that are sold to smelters. The combination of biological H2S production and selective metal recovery is currently marketed under the process name BioSulphide-Thiopaq. The process can be applied on a stand-alone basis or in conjunction with a conventional lime water treatment. Process advantages include: reduced lime treatment costs, reduced volume of waste sludge free of toxic metals leading to reduced long term environmental liabilities, selective recovery of metals and, in some cases, net profit from water treatment achieved through the sale of metal concentrates. Three case studies are presented to provide examples water treatment and metal recovery: the Caribou Mine, New Brunswick; the Phelps Dodge Bisbee operations, Arizona; and Falconbridge?s Raglan nickel mine in Quebec. A fourth case study is presented to highlight environmental control for treatment of ARD in the Leadville mining district of Colorado. Process flowsheets, capital and operating costs are presented for the four case studies

Jan 1, 2003

By Mike Santaluce

Smelting furnace rebuild projects often require a significant capital expenditure and an extended smelter outage. Smelter operators are increasingly searching for methods and initiatives to shorten furnace rebuild schedules, maintain manageable cost levels, enhance furnace performance and achieve excellent safety results. This paper describes the ?MEPC? Model for furnace rebuilds; a project driven approach which Auburn has developed in response to the need for improving furnace rebuild project outcomes. The ?MEPC? (Management, Engineering, Procurement and Construction) approach better addresses the unique challenges presented by furnace rebuild projects when compared to the traditional EPCM (Engineering, Procurement, Construction Management) model widely in use for these projects today. One key feature of the MEPC model is that a dedicated project management team with representation from all of the major project stakeholder groups is put in place at the onset of the project. The project management team has ownership and accountability for meeting overall project goals over the entire lifecycle of the furnace rebuild project. A second key aspect of the model is emphasis on project management as a completely separate project function with its own specific skill sets, techniques, tools and best practices. These features of the MEPC model offer several advantages in terms of improved planning, coordination, communication and alignment with project goals which contribute to the overall success of furnace rebuild projects. Similar MEPC concepts have been used to deliver excellent project results in other industries and the MEPC approach has been successfully utilized on furnace rebuild projects.

Jan 1, 2006

By Wang Haibei

China is the important country in terms of Ga, Ge reserves and products. These elements usually associate with lead and zinc ores such as in Fankou, Dachang and Lanping mines. Until now these metals could not be extracted from zinc residues effectively. The main reason is that it is difficult to separate zinc and iron. BGRIMM has carried out considerable research on this subject and some hydrometallurgical processes were developed. Zinc residues were pressure leached with a reducing agent such as zinc concentrates or SO2 at 110~130C. The final concentrate of H2SO4 was 30~50g/L. The metals such as Zn, Fe, Ga and Ge were dissolved into solution. In the leaching residue Pb and Ag could reach 20% and 2000g/t. The feed of solvent extraction was prepared from the leaching solution by pre-neutralization ? precipitation of Ga, Ge and acid dissolving. Then Ga and Ge were extracted by solvent extraction through P204 and G315 produced by BGRIMM. After stripping, metallic Ga was produced by electrowinning. GeO2 was produced by precipitation. The iron in raffinate was removed by the hematite process. The solution after removal of iron came back at the zinc neutral leaching stage. In 2003-2004, pilot tests were finished in BGRIMM in cooperation with Fankou Lead and Zinc Mine Ltd. And the extraction rate of Ga and Ge in the leaching stage was 94% and 83% respectively. The total recovery rate was 90% and 80%. It is estimated that the technology has a wide commercial use in the coming five years.

Jan 1, 2006

By Gordon Holcomb, George R. St. Pierre, Robert A. Rapp

Carbon/Carbon composites offer promise as high-temperature structural materials. A primary limitation on their application is the need to provide protection against oxidation in hot oxidizing environments. Silicon carbide conversion coatings have been shown to provide extended protection at temperatures of 1600°C. SiC coated C/C components have been used in several aerospace applications. In the present paper, the preparation of carbon fibers and their treatment during subsequent processing into coated components are discussed with particular emphasis on the processing variables that can result in improved oxidation resistance. In particular, the influence of substrate inhibitors and selective sealants for cracks in coated C/C components are analysed.

Jan 1, 1988

By J. P. Rodier

Despite the good years that the non-ferrous business is now enjoying, one should not forget that in this business growth rates are low, fixed assets are high and prices are more cyclical than in other businesses. Increasing environmental concern puts the industry under pressure. Lead and zinc companies are now profitable and profitability in the next ten years will depend on size of units, location, and choice between new technology and upgrading current ones. Implementation of Metaleurope was a strategic move. It produced a company of sufficient size to achieve new steps in cost cutting and yet remain flexible enough to deal with rising variety of primary and secondary raw materials.

Jan 1, 1990

By Krishna Kumar

"Growth of electronics waste (e-waste) and lack of appropriate disposal mechanism are the great concern for developing countries like India. The domestic generation of e-waste in India is rapidly growing with the development. The imported substance is also substantially contributing to the e-waste inventory. Recycling of e-waste is mainly carried out in unorganized units in India. The primitive recycling technique used by the unorganized sector is a great threat to the environment and the health of the operators involved in these profession. Therefore, improvement of technology used by these units towards a cost effective, environmental friendly alternative could be the solution to the present crisis. Few initiatives of recycling have, however, come up in recent years in organized units. The precious metals are still recycled in the developed countries. This report discusses the inventory, technology status, legal legislative and existing practices of e-waste management in India.1. INTRODUCTIONInnovation, research and development in the field of electronics and information and communication technology (ICT) lead to convenient, independent human life. Consumption of electronics and hardware products has enhanced by manifold. Electronics and hardware sectors have, thus, become the fastest growing sector in the world. Faster obsolescence of these products is forcing users to replace products with an advanced technology. Life cycles of these products are few years. Discarded electronics products are, therefore, accumulating alarmingly in our society. Electronics waste (e-waste) is a crisis not only due to its volume but also for presence of its toxic ingredients, like heavy metals (e.g. lead, mercury, cadmium, hexavalent chromium) and flame retardants such as poly brominated biphenyles and poly brominated diphenyles ether. These substances create potential occupational and environmental health hazardous."

Jan 1, 2011

By J. M. Brupbacher, D. C. Nagle

"The XD TM * approach to producing metal matrix composites employs an in-situ precipitation technique for the formation of the reinforcement directly in the matrix of interest. Key features include: thermodynamically stable reinforcement; clean particle/matrix interfaces, single-crystal reinforcement; size, chemistry, and shape control; uniform distribution; compatibility with conventional ingot techniques; and grain refinement.Using XD~ technology it is possible to simultaneously introduce a number of different reinforcements in a given matrix, thus allowing for designing the microstructure to meet a specific material need. Thus, XD1l'1 technology is a very useful technique for achieving ""designer"" or ""engineered"" microstructures. XD TM technology has been applied to a number of systems including AI, NiAI, TiAI and Cu. Materials property and processing benefits will be discussed."

Jan 1, 1988