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By Batric Pesic

Dissolution of gold with sodium bromate solutions of various compositions was studied by using a rotating disc technique. The role of bromide ion, acid and externally added bromine was examined. It was found that sodium bromate could not dissolve gold in the absence of either acid or bromide ion, or both. When acid was absent, no bromine necessary for gold dissolution could be produced. When bromide ion was absent, formation of soluble gold bromide species, AuBr,-, was not possible. Bromate concentration had a complex effect, and it was dependant on bromide ion concentration. For fixed initial bromide ion concentration, gold dissolution rate increased with sodium bramate concentration increase until certain level, beyond which further increase of bromate concentration decreased the gold dissolution rate. The negative effect of bromate was explained by the depletion of necessary bromide ion. Sulfuric acid concentration effect was a function of initially present bromine.

Jan 1, 1992

By M. K. Ghosh, B. C. Tripathy, A. Baral

Present work is focused on the recovery of Mn as a value added product from the leach liquor of scrap lithium-ion batteries (LIBs) of mobile phones by the method of precipitation. The LIBs were crushed and bene ficiated by wet scrubbing method to separate cathodic material, plastic and metallic parts. The cathodic material was found to contain 11.3% Mn, 10% Co, 2.4% Cu and 2.4% Li. The cathodic material was processed for leaching under the optimized condition developed by our group at CSIR-NML. Solvent extraction method was used to extract acid using organic extractant Tris(2-ethylhexyl)amine (TEHA) in order to reduce the consumption of alkali required during precipitation studies. The acid free leach liquor was subjected to puri fication for removal of Fe, Li, Cu and Co as precipitate at different pH. Systematic precipitation studies were carried in batch and continuous mode to recover Mn as Mn(OH) 2 at pH *10 which was further roasted at 450 °C for 4 h to get pure Mn 3O4.

Mar 1, 2018

By M. K. Mohan

Lead recovery from process solutions contributes not only to the conservation of resources but also clean environment. Zeolites are natural aluminosilicates, which finds applications as catalysts and in wastewater treatment. In the present investigation, studies were taken up on the processing of Pb from process solutions by zeolites. Effects of pH of the solution, time and type of zeolite viz. chabazite, mordenite, erionite and clinoptilolite on the removal of Pb from solutions was investigated. Rate of sorption was found to depend on the pH of the solution and about 99 pct. recovery was observed at pH 6. Optimal conditions were established for the maximum recovery of lead from process solutions. Possible sorption mechanisms were proposed. The calculated adsorption constants calculated from Langmuir and Freundlich equations showed that the adsorption of lead on chabazite was strong.

Jan 1, 1999

By F. -Z. Ji

Carbon injection into metallurgical slag is important in electric arc furnace (EAF) steelmaking for foamy slag practices and in nonferrous slag cleaning operations. The current publication presents kinetic data for coal injection into EAF slag to understand the interaction between injected carbon and metallurgical slag. Coal particles were injected into EAF slag and the kinetics were followed by gas and slag analysis. The results were analyzed, in terms of fundamental rate equations for each possible reaction step, as a function of temperature and slag composition.

Jan 1, 2003

By Y. Kumagai, F. A. Souza

"Electroless plating process has been used in many fields such as automobile and electronic industries. Solutions used in these processes must be disposed or treated. Commonly, in these solutions metal ions, organic materials and others chemicals are in very high concentration. It is very difficult to keep the environmental regulations for disposal of these materials, and the cost of the plating process becomes higher.The objective of this study was to investigate the recovery of components of those baths in order to decrease the cost of the plating process as well as to meet the environmental regulation.In this study the recovery metal ions, sulfate ions, phosphite ions and organic compounds were investigated. Organic compounds used in electroless plating solutions are the organic acids. In this work the solvent extraction of the most used organic acids included citric, lactic, succinic, tartaric and malic was studied. The solvent phase considered in these studies was ethyl acetate.About 95% of the metal ion was recovered by chemical plating onto mica powder. The hypophosphite remained is oxidized to phosphite and with the sulfate ion, both are recovered as calcium salts by selective precipitation in pH 7 and 2 respectively. Organic acids were recovered by solvent extraction using ethyl acetate as solvent phase and the best results were for lactic acid and succinic acid.Along with this study, was developed the analytical parameters to perform wastewater analysis by using Ion Chromatography, High Performance Liquid Chromatography (HPLC), Fourrier Transform Infrared Spectroscopy (FTIR). Ion chromatography was used to perform analysis of sulfate and phosphite ions in liquid matrix, HPLC was used to perform analysis of organic acids in liquid matrix and FTIR was used for characterization of the solids obtained in the recovery processes."

Jan 1, 1997

By Guanghui Li

In the paper, the recovery technology of gallium from zinc-leaching residue by cold-bonded coal-based direct reduction process following magnetic separation was developed. The results show that the scattered metal Ga can be concentrated obviously after the reduction of zinc-leaching residue briquette and magnetic separation of reduced product. At the same time, the volatilization of Zn in the residue is enhanced during the reduction. When the residue, bear¬ing 18.60% Zu.21.18% Fe and 527 g/t Ga, was reduced with coal at 1100°C for 150 min, the results of Zn volatilization of 9842% and Ga recovery of 89. 10% were obtained in reduction. After magnetic separation of the reduced product, the concentration of Ga in sponge iron is 2164 g/t, and the separation recovery of Ga reaches 92.42%. The enriched mechanism of Ga during reduction -separation process was studied by using electron microscope, scanning elec¬tron microscope, energy spectrum and mineralogical analysis. The investigations show that there is no formation of independent phase of Ga during reduction process. The Ga occurs mainly in metallic iron phase (the concentration of Ga in metallic iron phase is 0.04%-0,4%), in addition, there exists a little Ga in poorly crystalline sulphide (o.08%-0./5Y& Ow). But Go does not exist in most of glass and silicate phase. The affinity of Ga for metallic iron is the enrichment basis of Go in reduction, and it is also in favor of recovering Go during magnetic separation. Key Words: Gallium Zinc-leaching Residue Cold- Bonded Direct Reduction

Jan 1, 2003

By R. G. Reddy

Viscosities of alkaline metal oxide-silicate melts were estimated using our previously developed mathematical model. The structural based model considers depolymerization effects and related breakdown of the silicate network structure, on the addition of metal oxides to the melt. The developed expression: n =4.9x10 9 NO 0 T ½ exp(E/RT) poise was used to calculate the viscosities of various binary silicate systems such as, CaO-SiO,, MgO-SiO, and MnO-SiO,, as a function of temperature and composition. Excellent agreement was obtained between the calculated and experimentally determined viscosities.

Jan 1, 1991

By M. A. Neri

A lead-free solder alloy Sn-57.5Bi-0.5Ag has been developed by mechanical alloying and foundry processes, and has great potential as a lead-free solder system, to low temperature applications. The mechanical alloying powders show a microstructure different to the microstructure obtained by the foundry process for the same alloy. Its melting point of 142°C is slightly higher than that of eutectic tin- bismuth solder. Examination of the microstructure revealed that eutectic microstructure is refined by the mechanical alloying process Ag additions. The lamellar structure of tin-bismuth gradually disappeared with the process of mechanical alloying, while intermetallic compounds AgaSn phase was formed. The Cu-Sn intermetallic compound layer formed at solder-copper interface is the Cu6Sn5 phase. Keywords: Lead-free solder, Microstructure. Mechanical alloying

Jan 1, 2003

By P. M. Swash

The determination of the heavy minerals in beach sand samples is highly dependent on the preparation technique used. In this paper a simple reproducible method for the quantification of "recoverable" ilmenite, zircon, rutile and leucoxene by magnetic separation, is described. The procedure recommended yields information relevant to the metallurgical processing of the ore rather than to the total heavy minerals present in the samples. Finally the determination of mineral reserve estimations and grade assessments is greatly facilitated when this "mineral assay" method is employed. An assortment of other mineralogical methods are described including SEM, EMPA, XRD, XRF, Image analysis, Mossbauer. clerici and perm roll separations. The methods are briefly examined and the practical information that can be gained by using such techniques are reviewed. Experience has shown that an understanding of the relationship between the physical and chemical properties of the heavy minerals can contribute to the prediction of mineral particle behaviour. Such information may ultimately help reduce the prospect evaluation period and minimise expenditure on metallurgical testwork.

Jan 1, 1991

By Jianhui Wu, Jing Zhan, Chuanfu Zhang, Zhijian Wang, Chu-ping Xia

"A novel technology about interactive roast of complex bismuth sulfide ore with low grade and Pyrolusite was put forward using the low-grade bismuth sulfide ore and pyrolusite as raw materials. The predominance diagram of Bi-Mn-S-O system was drawn by thermodynamic calculations. Stable coexistence area ofBizO3 and MnSO4 and its control condition was obtained. The interactive roast conditions including roasting temperature, roasting time, the ratio of n(MnO2)/n(S), ventilation rate and so on are investigated systematically. The results show that the sulfur-retained ratio reaches about 98%, in which formation rate of MnSO4 was 94.04%, most of the residual sulfur in the ore exist in the form of BhsO32(SO4)10 in the roasting products The optimum roasting conditions were as follows: roasting temperature of 650°C, roasting time of2h, 1.4 for n(MnO2)/n(S) and 140L/h for ventilation rate.IntroductionBismuth is a ""green"" rare metal with the characteristics of safe, nontoxic and low melting point[l].The use of bismuth and its oxides is extending from traditional fields such as pigment, fusible alloy, bismuth class of drugs and metallurgical additives to the high-tech fields such as semiconductor, high-temperature superconducting materials and nuclear power and so on. Bismuth is one of the precious advantageous resources in China which owns the most abundant bismuth resources in the world. Bismuth metallurgical process is divided into the pyrometallurgy and hydrometallurgy [2-4]. Hydrometallurgy for bismuth is mainly used for the processing oflow-grade complex bismuth ore, whose key steps are oxidative leaching process of the bismuth sulfide ore by strong oxidants(FeCb, Clz, HNO2 etc) in hydrochloric acid system. Therefore, the corrosion of strong oxidants, high demand for equipments and poor operating environment are its inherent disadvantages. Pyrometallurgy for bismuth is mainly used for the processing of high-grade bismuth raw materials or concentrate, which is the main method for bismuth metallurgy at present."

Jan 1, 2013

By Frank M. Kimmerle

Spent Potlining (SPL) contains recoverable chemical elements (C, F, Na and Al) which are lost in stabilization or immobilization processes primarily aimed at eliminating cyanides and reducing leach rates of soluble fluorides prior to landfiling. They can be recovered in a variety of mineral forms for recycling in the aluminum industry and elsewhere. Alcan has developed a cost-effective hydrometallurgical route, combining a number of proven unit processes to destroy cyanides, recycle the chemical values and provide a zero-discharge process. Pilot plant studies of this Low Caustic Leach and Liming (LCL&L) Process prove that the fluoride scan be converted to acid grade fluorspar, while the sodium and aluminum are recovered as a sodium aluminate and caustic feed to the Bayer Plant operations. The remaining brick and carbon fraction constitutes a high ash solid fuel which meets TCLP leach criteria and whose reduced sodium content enhances its value as a chemical reducing agent.

Jan 1, 1994

By Christoph Zschiesche

Managing complex material streams within a lead smelting/reduction process has a long history at Aurubis. After modernization of the secondary lead smelter in 1991, Aurubis operates an electric furnace and a Peirce Smith converter to process complex secondary materials. This process links the copper and the lead metallurgy allowing Aurubis to properly combine primary and secondary process lines to optimize the processing of complex raw materials and smelter intermediates. However, combination of copper and lead metallurgy processing requires a continuous evaluation as raw material quality and composition varies. This paper describes Aurubis lead smelter processing and provides some fundamental considerations to optimize the lead processing, in particular with aspects related to speiss formation

By C. L. Lin

Transformation of linear grade distribution to volumetric grade distribution has been used to estimate the actual mineral liberation during wet, batch, ball mill grinding of a copper ore. The degree of liberation based on the multicomponent-multisize grinding liberation model using volumetric grade is lower than the apparent degree of liberation estimated from using King's linear intercept model.

Jan 1, 1987

By Roger Agnew

Sulphide ores mined by Inco Limited in the Sudbury District contain small quantities of cobalt. During beneficiation, cobalt distribution to various streams is similar to nickel. After smelting, nickel is selectively extracted by carbonyl refining and the cobalt remains in the carbonylation residue. This residue is processed in a specialized hydrometallurgical plant to produce precious metal residues, copper cathodes, and a nickel- cobalt carbonate intermediate product. The nickel-cobalt is shipped to Port Colborne where the cobalt is separated as cobaltic hydroxide and refined to metallic cobalt. This paper deals specifically with the recently constructed Electro Cobalt Refinery. The cobaltic hydroxide is dissolved and residual zinc, copper and nickel are removed by ion exchange and organics by a carbon column. The purified cobalt solution is fed to the electrowinning circuit where cobalt rounds are produced on stainless steel mandrels. In the design and construction of the refinery, special attention was directed to materials of construction both for the process equipment and the physical plant, operating control and flexibility, and the quality of the working environment. The end result is an efficient and clean operation which yields a product of excellent quality.

Jan 1, 1988

By Guohua Bai, Yuanbo Zhang, Guihong Han, Zijian Su, Daoyuan Zhang

"Specularite ores have poor hydrophilicity and ballability as well as inferior high-temperature reactivity, which restrict the large-scale application of them in the pelletizing and sintering production. Modified humic acid (MHA) organic binders are firstly used for pellet preparation from specularite in this paper. The results show that the drop strength of green pellets is 3.7 times/0.5m and compression strength is 12.5 N/P by using 1.0 wt% MHA as binder. Under the optimal experimental conditions of preheating temperature 980 °C, preheating time 12 min, roasting temperature 1280 °C and roasting time 10 min, the preheated pellets have the compression strength more than 400 N/P, and that of roasted pellets is 2747 N/P. The strength of finished pellets meets the requirements of blast furnace iron-making. MHA is a kind of more effective organic binder for specularite pellets compared with the inorganic bentonite.IntroductionAcid Pellets have advantages of good strength, uniformity particle size, high iron grade and good reducibility, which can be used as high-quality burdens for blast furnaces [1]. With fast development of Chinese iron and steel industry domestic magnetite concentrates with high grade of iron and good firing performances become shortage.Imported specularite ores have advantages of low price and high grade of iron (generally above 67 wt%), so the application of them in pellets is an effective way for sustainable development of pellet industry in China. However, the specularites have not been utilized in pelletizing and sintering at present because of the poor ballability and high-temperature reactivity [2, 3]. Most of the pellet plants use bentonite as binders, the amount of which is about 2~3 wt%. The pellet production practice shows that 90 wt% bentonite is still residual in finished pellets and reduces the iron grade [3]. Developing a new organic binder instead of bentonite is very important to the high-quality pellet production. On one hand, the consumption of bentonite is obviously reduced, resulting in decreasing the ironmaking coke ratio and slag discharge; On the other hand, the iron grade of finished pellets are improved, which brings the benefit for the ironmaking production."

Jan 1, 2011

By Sang Han Son

The vapor pressures of FeCL2 and ZnCL2 in the FeCL2?ZnCL2 system were measured by the transpiration method at 873K and 9I7K, The vapor pressure data were interpreted to indicate the formation of complex ions in the FeCL2?ZnCL2 melts, It is presumed that the complex molecule FeZnCl4 as well as FeCL2 and ZnCL2 exists in the vapors in equilibrium with molten FeCL2-ZnCL2 mixtures, The activities in the FeCL2-ZnCL2 system are shown a negative deviation from Raoult's law. These results suggest the formation of complex ions such as ZnCL14 in molten FeCI2?ZnCL2 mixtures.

Jan 1, 2003

By Shengli Wu, Mingyin Kou, Laixin Wang, Zhe Wang, Xinliang Liu

The sticking behavior of iron ores in the shaft furnace is one of the most important problems in the COREX melting progress, which directly influence the smooth operation and productivity of shaft furnace. Therefore, it is of great importance to study the sticking behavior of pellets in COREX shaft furnace. The results showed that porous metallic iron produced at the interface of pellets samples was the main reason for the sticking of pellets in the COREX shaft furnace. The SI (sticking index) and metallization rate increased with the reduction temperature and gas flow, and decreased with melting rate. However, the SI of pellets in the COREX shaft furnace could be decreased by the proper match of melting rate and reduction temperature, reduction temperature and gas flow, while the metallization rate of pellets were kept at a certain level. Furthermore, the matching of melting rate and reduction temperature was more effective than the matching of reduction temperature and gas flow.

Jan 1, 2016

By Prakash Venkatesan, Yongxiang Yang, Seshadri Seetharaman, Aida Abbasalizadeh, Jilt Sietsma

Electrolytic production of metallic neodymium is carried out in fused fluoride salts containing neodymium oxide. Two major challenges pertaining to neodymium production are (a) low oxide solubility and (b) possible fluorine gas evolution. A novel iron-based reactive anode is proposed and tested to overcome fluorine gas evolution during electrolysis of neodymium oxide in molten fluoride salts.

Mar 1, 2017

By Baozhong Ma, Qian Li, Yonggang Wei, Shiwei Zhou, Bo Li, Chengyan Wang, Hua Wang

The magnesium-rich nickel oxide ore (w (Ni) =1.09 %, w (MgO)=29.08 %) mixed with 6 % and 8 % anthracite were roasted at different temperatures. XRD and SEM/EDS techniques were utilized to characterize the phase and microstructure transformation of the ores. The results show that lizardite and chrysotile of raw ore were converted into forsterite and enstatite during reduction roasting process. Simultaneously, iron and nickel oxide were reduced and migrated from the initial magnesium silicate. Fe3Si were formed when the roasting temperature went up to 1300 ℃ and 1350 ℃, and a small amount of Ni was observed in it. Temperatures got too high were not benefit to the polymerization of ferronickel.

Jan 1, 2015

By Shengqin Zhang, Yousef Mohassab, Feng Chen, Hong Yong Sohn, Mohamed Elzohiery, Amr Abdelghany

The kinetics of hematite concentrate reduction by mixtures of hydrogen and CO of various compositions has been investigated as part of the development of a flash ironmaking process at the University of Utah. This process produces iron directly from iron oxides concentrates by the gas-solid flash reaction based on the partial oxidation of natural gas, resulting in a significant reduction in energy consumption and greenhouse gas emission. The reduction kinetics of hematite concentrate of an average particle size 21.3 μm by the above mentioned gases in the temperature range 1423 to 1623 K (1150 to 1350 ºC) was investigated. Hematite concentrate particles can be reduced to > 90% by any of these reductants in several seconds of residence time typically available in a flash reactor. The activation energy ranged from 214 kJ/mol for hydrogen to 231 kJ/mol for CO.

Jan 1, 2016