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By Michael L. Sorokin

The metallic nickel production by converting of nickel matte is analysed from the thermodynamic point of view using earlier developed thermodynamic models for sulphide, metal and slag phase. Three-suffix Margules equations are used to calculate thermodynamic properties of melts. Potential diagrams of Ni-FeS-OSiO2 system are calculated for various temperatures and Fe to Ni ratios. The diagrams used for consideration about possibilities of the direct one-stage metallic nickel production.

Jan 1, 1995

By J. Murphy

The economics of microbial coal desulfurization are affected significantly by the proper selection of the plant site and by maintenance of variables at suitable levels. High sulfur coal particles below 200 mesh show sulfate production rates triple those with 150 mesh coal but grinding costs are greater. Slurry solids density increases from 5% to 20% reduced the rate constant by a factor of 10. Coal added to a batch reactor in the stationary phase resulted in a sudden second exponential sulfate production phase indicating feasibility of lower cost continuous operation. Successful operation in the absence of beef broth, yeast or added nutrients at non-sterile conditions enhanced projected economics. Finally, the need for adequate agitation and aeration was well established.

Jan 1, 1985

By Victor Bredykhin

The reasons of formation low quality cathode deposits and conditions of the anode passivation in electrorefining of copper silver alloys with increased (more then 5%) silver content in electrolyte, g/l: Cu - 40; H2SO4-50; 150 and 250; T= 401C have been investigated. As it is shown, increased acidity, anodic current density and silver content in anodes favor passivation. The assumption is made that the ingress of silver on cathodeis the most probable reason of growing dendrites on cathode. We have determined that addition of ethylene carbonic acid to electrolyte in the amount of 3,5 ÷ 10 ml/l suppresses the dendrite formation.

Jan 1, 2006

By Donald R. Sadoway

Fused salt electrolysis is used extensively in the primary extraction of metals (electrowinning), in the refining of metals (electrorefining), and in the formation of coatings (electroplating). In the case of rare earths, fused salt electrolysis competes with nonelectrochemical processes to make the same products. However, fused salt electrolysis has the potential to produce these metals in a variety of technologically useful forms: thin films and epitaxial layers, powders, and a variety of nonequilibrium structures. The theory and practice of fused salt electrolysis as it applies to the extraction, refining and plating of rare earth metals are described. The potential of fused salt electrolysis to synthesize advanced materials containing the rare earth elements is assessed.

Jan 1, 1989

By Vinay Kumar, Jae-Chun Lee, Rakesh Kumar, Manis Kumar Jha, Archana Kumari, Pankaj Choubey

Present work is a part of developing novel recycling technique for waste printed circuit boards (PCBs) i.e. the liberation of metals from PCBs by organic swelling followed by the treatment of resin to remove/ recover hazardous soldering materials. In order to recover the hazardous metallic constituent lead from the liberated resin, initially the leaching studies were made using fresh solder containing 63.9% Pb and remaining tin. Experimental results obtained in different conditions viz. time, temperature and acidity showed -97.20% of lead dissolution with 6M HNO3 at solid to liquid (S:L) ratio 1:10 (g/mL) and temperature 90°C in 75 minutes. The result of the studies validated with crushed PCBs shows that almost total lead and tin was leached out with 6M HNO3 and 6M HC1 respectively at S:L ratio 1:10 (g/mL) and temperature 90°C within 50 minutes. The results will be useful for the treatment and safe disposal of PCBs resin.

Jan 1, 2011

By R. P. Rao

In rare earth (RE) based phosphors, high luminous efficiency is possible due to their restricted emission limited to specific narrow bands. In general, these phosphor materials consist of RE ions as activators/sensitizers and/or hosts. Development of various phosphor host matrices such as alkaline earth chlorophosphates, aluminates and silicates activated by Eu(2+) as blue component, borates and phosphates of lanthanides and alkaline earth aluminates doped, with Ce/Bi and Tb as green component and Eu(3+) activated yttrium oxide and vanadate as red component has been described. Luminescent characteristics, color coordinates and suitability of these phosphor materials in high efficiency new generation lamps are presented and discussed.

Jan 1, 1989

The physico-chemical principles of chloride hydrometallurgy are reviewed to rationalise the complex chemistry in chloride-based processes for metal sulphides in terms of the predicted Eh-log[Cl-] relationships, measured changes in activity of H+, Mz+, Cl- and solubility of Ag(I), Cu(I), Cu(II), Pb(II), Ni(II), Au(III), Sb(III) and Bi(III). These changes reflect the nature of chemical speciation, competing effect of hydration/hydrolysis and chloro-complexation,composite effect of increasing acid and/or salt concentration and decreasing water activity. Rate data for the dissolution of PbS and ZnS in HCl containing Fe(III) or Cu(II) are compared and contrasted to highlight the effect of acid and chloride concentration, water activity, and the nature of oxidant. It is shown that LiCl, NaCl and HCl influence the kinetics of oxidative PbS leaching based on their effect on solubility of PbCl2 co-precipitated with elemental sulphur on the mineral surface. Evidence for the beneficial effect of Cu(II) in sulphide leaching is discussed.

Jan 1, 2003

By Cyro Takano

This paper is a contribution to fundamentals data on the equilibrium metal/slag for refining silicon in relation to Ca and Al as impurities. Silicon containing 0.1% Al and no Ca was placed in contact with a slag of various contents of CaO, SiO2 and Al2O3. Slag Al2O3 contents were 11.4%, 25.1% and 29.6%, keeping the ratio %CaO/%SiO2 constant and equal to ~0.53. The experiments were conducted at 1550oC, in a graphite crucible with argon atmosphere. The equilibrium was observed with low and medium content of Al2O3. The derived activities coefficients of Ca and Al in dilute solution of Si presented good correlation with those of the literature. Parallel reactions with formations of SiO(g) and CO (g) were also observed.

Jan 1, 2006

By L. A. Barta

A new process for the leaching of chalcopyrite concentrates has been developed and tested in miniplant campaigns and locked cycle testwork carried out between 1996 and 1999. The process involves pressure leaching in a sulphuric acid solution, e.g. raffinate from copper solvent extraction. Iron in the feeds is precipitated predominantly as hematite in the autoclave, simultaneously with copper extraction. Gold and silver in the pressure leach residue are recoverable by conventional cyanidation, following flotation to remove elemental sulphur by-product. The results of recent miniplant tests and batch locked cycle tests are provided.

Jan 1, 1999

By Corby G. Anderson

Today, with a stringent economic and environmental climate prevailing in the copper business, there is increased interest in evaluating new processing alternatives for production. Hydrometallurgical pressure oxidation of copper concentrates is one of the more viable approaches and several technological candidates have emerged. Of these, an overlooked but industrially proven methodology utilizing nitrogen species catalyzation in the oxidizing pressure leach system may prove to be a feasible process alternative for the future. In this paper, the history of the system and its application to chalcopyrite concentrates will be outlined. In particular, a methodology for effective treatment of precious metals bearing chalcopyrite concentrates via partial oxidation at low temperatures and pressures will be discussed. Finally, the perceived economics of this unique industrially proven process will be delineated.

Jan 1, 1999

By Takeshi Yoshikawa

For the development of low-cost silicon refining process for solar cells, the present authors have been studying the low temperature refining technique, ?solidification refining of Si with Si-Al melts at 1173 ? 1273K?. In the present work, we have investigated the B removal in that refining, utilizing the segregation effect and also the effect of Ti addition to the melt. Segregation ratio of B between solid Si and Si-Al melt was measured by the temperature gradient zone melting technique and it indicated the B removal fraction would be as much as 90%. Titanium addition to the melt was found to produce the TiB2 precipitation with soluble B in that melt and bring the effective B removal of refined Si to its content of 1ppma.

Jan 1, 2006

By Henry Freiser

For the last several years, a systematic investigation of the equilibrium extraction behavior of selective tervalent lanthanides with representative chelating extractions of a variety of chelating agent families has been undertaken for the purpose of learning how to obtain chelating extractants of improved selectivity for separating individual lanthanide ions. The equilibrium extraction data (expressed as log Kex) for each reagent system are linearly related to the reciprocal ionic radius of the tervalent lanthanide ions. The role of adduct formation, steric hindrance, as well as the nature of the bonding atom in the chelate ring, represent some of the factors affecting selectivity arising out of our database of over 200 individual extraction systems, which will be discussed.

Jan 1, 1989

By V. M. Paretsky

Recent developments made in the Gintsvetmet Institute in the field of autogenous smelting processes have confirmed that autogenous smelting continues to be the main prospective technology for pyrometallurgical processing of sulfide raw materials. This technology ensures energy conservation and environmental safety conforming to the current world standards for production of heavy non-ferrous metals. Two alternative processes of single-stage autogenous smelting producing white metal as well as high-basic ferrite-calcium slags have been developed and can be recommended for technical modernization of Russian copper smelters.

Jan 1, 2002

By Stephan Mulch, Christian His, Patrick M. Stephan, Thibault Champion

"When fuel costs increase dramatically, waste to energy (WTE) conversion technologies become a good alternative to produce energy. The potential energy available in domestic wastes, in developed countries, could be upwards of 4% of their total energy needs. Due to low energy recovery and low level of treated domestic wastes in many countries, the energy coming from waste is generally less than 0.5% of the country needs.Domestic waste incineration can convert heat to electricity for industry and housing and allow waste volume reduction in countries where land fills are a scarce resource.There is a request to improve existing combustion technology by increasing energy recovery with better heat transfer in the boiler and also by increasing lining durability with more resistant materials and technologies.The knowledge of corrosion phenomena and material performance allows Saint-Gobain Group to develop and propose high performance refractory lining solutions.IntroductionThe interest in alternative energy has been growing dramatically in the two last decades due to several combined factors, such as global energy demand, fuels prices evolution (e.g. crude oil, Figure 1) or environmental and geopolitics factors"

Jan 1, 2008

By J. L. Delplancke

During copper electrowinning in sulphate electrolyte, intense oxygen evolution takes place at the anode. Lead alloy anodes are progressively replaced by dimensionally stable anodes in order to avoid the cathode contamination by dissolved lead. The electroactive coating of these anodes has to be as cheap as possible, adherent to the substrate, electrochemically stable and has to be efficient at high current density and high temperature. This requirement is even demanding in case of copper electrodeposition for the production of thin copper foils for the electronic industry. The production of thin (20 µm thick) copper foils for the printed circuit boards requires high purity copper electrodeposited at a current density as high as 7,000 A/m2. The choice of a long term coating composition is driven by economics. The purpose of this paper is mainly to review the anode compositions suitable for copper electrowinning and for copper electrodeposition at high current density. A short description of preliminary results obtained with a new anode coating on a titanium substrate is also presented.

Jan 1, 1999

By L. L. Ludwig, S. E. James, B. L. Motycka

Significant modifications to the electrolytic zinc plant operated by Big River Zinc Corporation were made at the end of the 1990's resulting in increased capacity and improved efficiencies. A new cell room, with the innovative use of acid-resistant concrete cells and a modern ventilation system, was installed to raise the capacity from 80,000 tonne/y to 106,000 tonne/y of finished zinc. Improvements to the leaching section include the conversion from a single to a two-step process, with associated equipment changes, to improve the quality of the residues produced. Another key change is the construction of a facility to allow the use of zinc oxides from secondary sources as a feed to the plant. This paper describes these improvements and the current operations.

Jan 1, 2000

By Jung-Ah Kim

Precipitated Calcium Carbonate (PCC) is obtained through calcination, hydration, and carbonation. Thus, the change in each process condition determines the particle size or morphology of PCC. To date, studies on precipitated calcium carbonate have mainly focused on process manufacturing PCC, aimed matter. Still, few studies on calcination or hydration have been conducted. Therefore, this study sought to investigate the effect of hydration condition on the synthesis characteristics of aragonite PCC. Results showed that the particle size of calcium hydroxide changed based on the variation of the initial hydration temperature. In particular, higher initial temperature resulted in the larger particle size of calcium hydroxide used in synthesis. The particle size and yield of aragonite also increased when calcium hydroxide made at high temperature was used. The water/solid ratio or total amount at the hydration time had no effect on the manufacturing process of aragonite, however.

Jan 1, 2006

By Peter J. Hancock

The pyrometallurgical .processing of non-ferrous, complex materials and wastes will be surveyed. Pyrometallurgy offers the most versatile way of processing a large variety of such materials because of its high temperatures, closely-controlled oxidation potential and the availability of commercially-proven reactor configurations. Some current industrial applications will be reviewed and possible new applications as well as future trends will be outlined.

Jan 1, 1994

By V. A. Shumsky, I. P. Polyakov, N. M. Ospanov, M. A. Lyamina, N. N. Ushakov

Studies on the kinetics of the competitive processes of PbS volatilization and PbS oxidation, as applied to the heat and mass transfer conditions in the flame of the Kivcet furnace, revealed that the rate-determining factor is the supply of heat. Therefore, low yields of fume in the autogenous flash smelting of lead sulphide feeds are noted despite the high volatility of PbS at 1,300-1,400°C. Dust formation in the autogenous flash smelting of Kivcet-smelters does not exceed 5-7%, of which fumes amount to ~ 80%. Using extra fuel during autogenous smelting involves the mismatch of the sulphide oxidation rate and the release of heat in the flame, and increases the fume yield. This is a major cause of the high dust formation in pilot plant trials. The analysis of dust formation in the Kivcet smelting of oxidized lead feeds in an industrialscale smelter shows an overall increase of dust formation (up to 10% of the feed), with fumes constituting ~ 80% of the dust. A pronounced increase of the zinc component of the fumes is also noted. Lead

Jan 1, 2000

By Sharon K. Young

What might an ideal leach-to-cathode/product system look like in the next century? The paper looks at the synergies of the 60's and 70's that led to the highly effective copper leach SX-EW system of the 90's. Standing in the year 2020 focuses on what breakthrough technologies might make possible a next generation leach/extraction/metal recovery system. Many of the pieces of such a technology have been developed, even piloted: in situ leaching, enhanced bioleaching, heap leaching of fine particles, resin in pulp, ion exchange, alternate anode reaction electrowinning, novel anode coatings. With nearly non-existent research on the part of individual large companies, the greatest challenge may not be inventing the technologies but rather inventing an industry "will to create."

Jan 1, 1999