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By Mao Chen, Baojun Zhao, Xiangfeng Cheng, Zhixiang Cui, Leonel Contreras, Anh Nguyen

Smelting is an important process in copper production to produce matte and slag.The slag,containing about 1–12% Cu can be further processed to recover the copper contaminated, but recycle of the slag concentrate reduces overall productivity and efficiency of the operation. The best solution is to minimize the copper loss to the slag. The entrained matte droplets in copper smelting slag may originate from a few sources. The present study aims to investigate possible copper matte loss mechanisms by visualization of room temperature experiments and high-temperature examination. It is believed that the gas bubbles from the matte phase disperse the matte droplets into the slag causing entrained matte in slag. Analyses of quenched slags from industrial operation and laboratory experiments confirmed that matte droplets in the slag are extensively associated with the gas bubbles. Water model is used to simulate the procedure and the bubble behaviors at the liquid-liquid interface are observed experimentally with a high-speed camera.

Mar 1, 2017

By N. M. Komkov

The main operation of obtaining zinc from sulfide raw materials by hydrometallurgical technologies is the oxidation roasting of zinc concentrates in fluidized bed furnaces. The technical-economic parameters are determined by the parameters of the roasting process, which depend on the composition of the initial raw materials, the temperature of the bed and on other factors. The predetermined roasting temperature is maintained due to the change of specific efficiency as well as to the quantity of the heat removed from the bed. The efficiency of caissons depends at a high degree on the composition and the thickness of the accretion formed on the surface of the caissons. Forecasting the roasting results is impossible unless we know the mechanism of the accretion formation. The aim of the present paper is the thermodynamic analyses of the behavior of the charge compositions under roasting and the determination of the potential mechanism of the accretion formation. The thermodynamic analyses show that under conditions of the oxidation roasting the thermodynamic probability of the formation of zinc sulfate is higher than the probability of the oxide formation until a temperature of873 OK is reached. The thermodynamic probability of the formation of the lead sulfate is higher than the probability of oxide formation in the entire temperature range of roasting. The probability of formation of ferrites and silicates of zinc decreases only insignificantly the sulfate stability. The results of the investigation of the accretions composItion formed under roasting of concentrates with particle sizes less than 0.02 J..lm (60%), containing 65% of sphalerite (ZnS), 12% of pyrite and chalcopyrite (FeS2 and CufeSz) each, 3% of galenite (PbS), 7% of silica and other non-ore minerals, have shown that the composition of accretion varies depending on the depth of the accretion layer. The accretions on the caissons and the thermo-siphons consist mostly of zinc sulfate (more than 50%). The accretions of forehamber consist mostly of zinc oxide. They also contain ferrites and silicates. The formation of the sulfate zinc accretion in the cold parts of the fluidized bed furnace (the caissons and thermo-siphons) may be explained by a lower temperature on the surface and probably by a catalytic influence of the present oxides in the formation of S02 and sulfates. The nature of the structure of the accretion in the hotter parts of the furnace may supposedly be explained by the formation of elemental vaporous zinc during roasting.

Jan 1, 2003

By Chen Song

Cobalt basic carbonate particles were precipitated from 1.0mol cobalt nitrate or cobalt sulfate solution with ammonia carbonate. By controlling the zeta-potential of the particles and the ionic strength of the solution, the uniform particles with ellipsoid or rod shapes were obtained. During the precipitation process, the interface tension was diminished to the minimum and therefore the Ostwald ripening and secondary nucleation were both inhibited. The morphology and the size control by zeta-potential seem to be the result of thermodynamics rather than classical crystalline kinetics. The particle sizes were in the range of 0.4-0.6, 0.3-0.4 micrometer. After thermolysis, the spinel-type C0304 particles were produced. The morphologies of C0304 particles were similar to that of their precursors.

Jan 1, 2003

By G. Roderick Eggert

Material criticality reflects the degree to which a raw material is both necessary and subject to supply-chain risks. This study compares the criticality of selected raw materials from the differing perspectives of the manufacturing sectors of China, the European Union, Japan and the United States.

By Denise Corrêa de Oliveira

Common dry batteries use zinc as the negative electrode. Producers commonly use additives such as mercury to prevent corrosion and to increase the mechanical resistance of the zinc anode. Alkaline batteries also contain it, as an anti-corrosive agent. When mixed with the common municipal solid waste, heavy metals as zinc and mercury pollute soil and ground water supplies, moving to the food-chain and affecting human health. Due to these possible damages, this kind of waste must be properly disposed, or recycled. Thus, even in low amounts (ppm) in batteries, mercury has to be eliminated or, at least, its content should be reduced. This work presents the use of pyromettalurgical processes, to reduce mercury content and recover zinc. The tests involved batteries treatment at temperatures from 300° to 1000°C. Mercury is eliminated up to 650°C, and zinc is evaporated at higher temperature treatment. C

Jan 1, 2001

By Albert W. Spitz

Profitably recovering copper and precious metals from copper bearing scrap is a demanding and frustrating combination of art, science and economics. With fluctuating markets, varying raw materials and increasingly stringent environmental regulations requiring process revisions, practically everything is changing. The volatile copper market constantly shifts the percentage of copper in the scrap that can be economically processed. Scrap that has value one day may incur a disposal cost the following day. Also with less copper in the scrap, more residuals, slag, fume, etc. are generated which frequently present disposal problems and infrequently generate income. The ever increasing amounts of electronic scrap add value to the copper produced by virtue of the precious metals present. Printed circuit board materials create more slag and organic off gases which must be treated. Finally, the emphasis on reducing emissions of organics and other metals, especially lead, is a continuing challenge. Stack gases, fugitive emissions and ambient air quality all demand constant surveillance.

Jan 1, 1997

By José Roberto de Oliveira

In a smelting reduction process the reduction reaction occurs predominantly in the liquid state. The main reduction agent is the carbon from the carbon saturated iron bath. The aim of the present work was to determine the velocity equation and the rate constant of the reduction rate of MnO content in a Mn0-SiO2-Fe0 slag by iron saturated carbon and the carbon dissolution rate in a Fe-Mn bath. The manganese content in the iron bath was in the range of 5 to 15 wt.%. It was observed that the rates of carbon dissolution in all Fe-Mn baths are faster than the rates of MnO reduction by the carbon saturated liquid iron.

Jan 1, 1999

By Patrick R. Taylor

Coatings of TiCIFe have been produced by Reactive Plasma Spraying using ilmenite ore concentrate as the feedstock powder and methane as the reactive gas. A free energy minimization analysis of the ilmenite-methane system is presented. The coatings have been characterized by x-ray diffraction and SEM. The microstructure of the coatings indicates good interparticle cohesion. The composition of the coating is deficient in iron compared to the initial Fe to Ti ratio found in ilmenite.

Jan 1, 1998

By Naixiang Feng, Shaohu Tao, Zhihui Wang, Yuezhong Di

"A novel vacuum aluminothermic reduction lithium process was developed in present work which used lithium carbonate, alumina and calcium oxide as raw material. The process mainly contained three steps. The first step is that LiA102 clinker is prepared in ambient environment, then metal lithium is vacuum extracted from LiAl02 clinker with aluminum power as reducing agent, and the last step is that alumina is leached from the reduction residue with a mixture of sodium hydroxide and sodium carbonate. The results show that the lithium reduction ratio can be over 95% under the conditions of reduction temperature 1423K, reduction time 3h, and aluminum excess 20%. The main components of reduction residue are CaO· Al203 and 12Ca0·7Alz03. The alumina leaching rate of calcium aluminate in residue is over 80%. High-whiteness aluminum hydroxide can be obtained by carbonation precipitation of the reduction slag leaching solution.IntroductionWith a density about half of water, lithium is with the lowest density of all solids, mere 0.5 g/cm3 at 20 °C [l]. Lithium is widely used in aerospace, aviation, nuclear-generated power and electric battery industry. Nowadays, over 90 % of the world's primary lithium is produced by molten salt electrolysis [2-4]. But the development of molten salt electrolysis will be effected by some factors: cost, environment, and so on. Vacuum thermal reduction may be used extensively in future because of its low-energy consumption, high-purity and short-cycle."

Jan 1, 2013

By Gerhard Bayer

X-ray and thermoanalytical studies were carried out on the formation and stability of Ca-, Mg-and Mn-tungstate, and of the corresponding minerals scheelite and wolframite. The tungstates were synthesized by different methods: precipitation from solution, solid state reactions, displacement reactions with solutions and in the solid state. The reactivity of natural scheelite and wolframite with different salt solutions and in mixtures with other minerals was investigated.

Jan 1, 1989

By Akihide Nagao

The behavior of impurity hydrogen that is contained in starting material or picked up during processing has been little investigated up to now. The hydrogen microprint technique is applied to determine the microscopic location of impurity hydrogen during deformation in aluminum without hydrogen charging. Three kinds of pure aluminum of 99.99% are prepared, in which hydrogen content is varied by changing the atmosphere when they are melted and heat-treated. After rolling, tensile specimens with a gage size of 4 x 4 rnm and 0.5 mm in thickness are stamped out from these three kinds of aluminum sheets. These specimens are covered with a liquid nuclear emulsion of silver bromide crystals, stretched by 5,10 and 15 percent plastic strain or fractured, developed and fixed. SEM micrographs reveal a number of silver particles on the slip lines and on the grain boundaries. Also shown is that the more hydrogen present in the specimen, the more silver grains appear on the slip limes and on the grain boundaries. Consequently, it is concluded that impurity hydrogen is transported to the surface with gliding dislocations during deformation.

Jan 1, 1998

By Sen-xiang Yang, Xin-teng Liang, Gui-jun Li, Jian-hua Zeng, Yong Chen

"This research is based on PANSTEEL 120t steelmaking converter technology to have the quantitative description of the time needed in uniform mixing of molten steel in the converter with the computer. In present work, the numerical simulation approach is used to analyze oxygen lance nozzle, the flow condition of oxygen and flow status of molten steel in the converter. The various oxygen jet flows that come out from different angles and the flow status of all kinds of jet flows in the converter have also been simulated. All of the simulation parameters are based on the specifically practical conditions according to the physical conditions of PANSTEEL 120 t steelmaking converter. Through numerical simulation, the angle parameter of the oxygen lance nozzle is 16 °. The optimized oxygen lance 536-16 has a good performance in industrial application. This kind of phenomenon shows that the ways and processes of numerical simulation in this research are right.IntroductionThe oxygen lance system is the significant process in semi-steel making converter. It's related to whether the converter or even the whole system can function well. While in actual production, many problems emerge in the process of using the former oxygen lance, such as re-drying, slopping, high lance position, dead burning and even blowing out. In continuous fast-paced process, the unstableness of oxygen lance will lead to speed droop or even stop pouring. Analysis shows that all these problems are not only related to the raw materials but also the design of oxygen lance. Bad oxygen lance's scorification kinetics condition and low content of FeOn in early slag are the direct factors that we cannot easily control in steelmaking at present [l]. Therefore, the good scorification kinetics condition which is related to nozzle has good influence on BOF steel making."

Jan 1, 2013

By Takaaki Ishikawa

The distribution equilibria of lead, zinc and copper between CaO-Si02-Ah03 melts and liquid copper were measured at 1623K under a controlled H2-C02 atmosphere. The distribution ratios were plotted against the oxygen partial pressure, and reasonable oxide forms dissolved in the melts were estimated from the slopes of the plots. The activity coefficients of zinc oxide (ZnO), lead oxide (PbO) and cuprous oxide (CuOQs) increased with increasing slag basicity, defined by Xcao /XSiO, The temperature dependence of the activity coefficients was also measured.

Jan 1, 2003

By Richard D. Hagni

Reflected light microscopic examination of particles from laboratory experimental copper flash furnaces operated under varied furnace conditions shows that the particles exhibit a wide range in mineral compositions and mineral abundances that correlate with partial pressure of oxygen and concentrate/oxygen ratio. Chalcopyrite, bornite, and digenite are more abundant under low oxygen conditions. With increasing oxygen, metallic copper, delafossite and cuprite become increasingly abundant. The extent of particle agglomeration during flight varies with the furnace. Those products from the larger furnaces exhibit the greater degree of agglomeration. Significant particle fragmentation also is evidenced by cracking and brecciation of some particles.

Jan 1, 1991

By Takaaki Ishikawa

The distribution equilibria of lead, zinc and copper between CaO-Si02-Ah03 melts and liquid copper were measured at 1623K under a controlled H2-C02 atmosphere. The distribution ratios were plotted against the oxygen partial pressure, and reasonable oxide forms dissolved in the melts were estimated from the slopes of the plots. The activity coefficients of zinc oxide (ZnO), lead oxide (PbO) and cuprous oxide (CuO0.5) increased with increasing slag basicity, defined by XCao/Xsio2 The temperature dependence of the activity coefficients was also measured.

Jan 1, 2003

By J. Méndez-Nonell

The thermodynamic and chemical properties of SrSO4 and SrS in a gaseous flow of CO and CO2 at high temperature are discussed. The thermodynamic analysis of the system was made using data from the literature. The results obtained from the thermodynamic analysis were experimentally verified using the thermogravimetric technique. The experimental results suggest the formation of a complex compound between SrO and SrSO4. It was also found a change in the chemical mechanism of the process between SrSO4 and CO-CO2 and in the chemical mechanism of the process between SrS and pure CO2.

Jan 1, 1995

By M. H. Staia

A Venezuelan ilmenite concentrate has been chlorinated at a temperature of 700" C by carbon tetrachloride. In the experimental rig, built at laboratory level, the direct chlorination process yielded a TiCI, recovery of approximately 85% after 280 minutes processing. The partial pressure of carbon tetrachloride was nearly atmospheric (0.94 atm). Product vapors from the reactor were fractionally condensed in a condenser which was maintained at a temperature of 250°C meanwhile TiCl, vapors were condensed in refrigerated coils at a temperature of -20°C. The concentrate used in this investigation was obtained by applying gravitational and magnetic concentration methods to the black sands. The experimental results have shown the need to asses the influence of the weight ratio of ilmenite to carbon tetrachloride on the resultant products. The equilibrium of the heterogeneous system has been calculated taking into account the initial experimental conditions.

Jan 1, 1995

By Sarel Johannes Francois Gates, Ida Kero, Yan Ma, Gabriella Tranell

During the tapping and casting of manganese ferroalloys, fumes are generated and released to the working environment. The fumes are mostly composed of metallic oxides generated due to reaction between high temperature molten metal and ambient oxygen in the air. From an environment perspective, it is important to limit these emissions. However, to do so, it is important to understand fuming mechanisms and kinetics as well as fume compositions, i.e. element behavior during the oxidation process of liquid manganese ferroalloys. Silicomanganese alloys are composed of aminimum of 65 wt% Mn and 17 wt% Si, 2 wt% C as well as minor and trace elements. These elements include Fe, Mg, Al and other elements originating from ores and reductants. Trace elements behavior in fume from liquid silicomanganese generated under an impinging air jet in the temperature range of 1450–1700 °C has been investigated in this work. The thermodynamic and kinetic conditions governing the generation mechanisms are discussed.

Mar 1, 2017

By Jianhua Xin, Min Chen, Lei Xu, Haohua Deng, Nan Wang

A mathematical model of converter slagging and steelmaking process by replacing part of lime with limestone is established. The rate equations of oxidation reactions and lime dissolution in converter under the limestone substitution proportion increasing from 25 to 50% can be obtained and the effects of limestone substitution proportion on the variations of the composition of hot metal, slag and converter gas during the steelmaking process are investigated. In the process of converter slagging and steelmaking by replacing part of lime with limestone, increasing the hot metal temperature and the lance height could be favor to increase the content of FeO in the slag and accelerate the limestone decomposition and dissolution. With the limestone substitution proportion increasing from 25 to 50%, the maximum of oxygen supply ratio increases from 10.7 to 19.7% and the temperature drop of converter bath is 8–60 °C.

Mar 1, 2018

By C. J. Lewis

This presentation concerns calcium oxide-better known as high calcium quick lime High calcium quicklime is produced by calcining high calcium limestone, mostly in the many rotary kilns located throughout the United States and Canada. This paper presents suggestions on the handling of lime based on field experience. The subjects covered are chemical analyses, transporta¬tion, lime storage, lime slaking to form a water slurry of calcium hydroxide solids, slurry transportation, slurry viscosity, and scaling of lime slurries. It is hoped that the comments on the foregoing areas will be of use to those designing or operating lime systems.

Jan 1, 1992