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By Zhijing Zhang, Ramana G. Reddy

"The viscosity of molten oxides is one of the important physical properties since viscosity has a decisive influence on fluid flow. The knowledge of the viscosity of molten oxides is essential for modeling and controlling of metallurgical process. In the present study, viscosities of high basic Na2O-B2O3 and Na2O-SiO2 binary melts and viscosities of Na2O-SiO2-B2O3 ternary melts were measured as a function of temperature and composition. Experiments were carried out using rotary viscometer and graphite components. Our experimental results were compared with those in literature. Based on the current experimental data, the previously developed viscosity model was modified. The characteristic features of viscosities of these melts have been discussed. The predicted viscosity results are in excellent agreement with the present experimental data in the temperature range with molten state samples. IntroductionThe viscosity of molten oxides is one of the important physical properties since this property has a decisive influence on fluid flow, and is one of key factors to be taken into consideration in process modeling. The manufacturing operations require the viscosity of molten oxides to be within certain ranges. Although, some viscosity measurements on borosilicate systems have been carried out [1-4], the viscosity data in literature are available only for a few temperatures and cover small composition ranges. The agreement between the results of these works is not satisfactory [I-4]. Even the viscosities of binary systems Na2O-B2O 3 and Na2O-SiO2 generally are well studied, the available viscosity data in literature are only found in the composition range of O to 0.333 mole fraction ofNa2O. The aim of the present study is to provide a base with accurate experimental data for reliable model extrapolation."

Jan 1, 1999

By Michael Zinigrad

The quality of metallic materials depends on their composition and structure and these are determined by various physico-chemical and technological factors. To effectively prepare materials with required composition, structure and properties it is necessary to carry out a research in two parallel directions: Comprehensive analysis of thennodynamics, kineties and mechanisms of the processes taking place at the solid-liquid-gaseous phase interface during welding processes and development of mathematical models of the specific welding technologies. We have developed unique method of mathematical modeling of phase interaction at high temperatures. This method allows us to build models taking into account the thennodynamic characteristics of the processes, the influence of the initial composition and temperature on the equilibrium state of the reactions, the kinetics of heterogeneous processes, the influence of the temperature, composition, hydrodynamic and thennal factors on the velocity of the chemical and diffusion processes. The model can be implemented in the optimization of various technological processes in welding, surfacing, casting as well as in manufacturing of steels and non-ferrous alloys, materials refining, alloying with special additives, removing of non-metallic inclusions.

Jan 1, 2003

By Basant L. Tiwari

An electrolytic process, based on a three-layer concentration cell, to extract magnesium from commercial aluminum alloy scrap has been examined. The process was repeatedly tested at 1025 K with two cells of d1fferent sizes, 0.6 kg and 5 kg feed aluminum, to have a better understanding of the opera ting parameters and evaluate the scale-up potential. In both cells, the magnesium content of the scrap was selectively reduced ?from 1. 1 to less than 0.1 wt.% at anodic current dens-Hy as high as 1. 1 A/cm2 with current efficiency exceeding 85%. Magnesium was recovered in the form of salt coated globules. Comparison of performances for the two cells suggests that the process can be scaled up. With further development, this process could become a viable alternative for demagging secondary aluminum.

Jan 1, 1985

By N. Menad

Thermal treatments of five different types of non-ferrous metallurgical wastes, under controlled atmosphere, were carried out at temperatures lower than 800 °C. The aim of these treatments was to reduce the toxic elements content and to increase that of valuable metals in the residue. <Best results were obtained by their treatments in air or hydrogen or successively both of them. Simple treatments using air or hydrogen of three samples allowed the elimination of more than? 95 % of their toxic elements and&apos; almost doubled their valuable metals&apos; concentration. For the rest two samples, combined treatment was necessary for their efficient decontamination and the concentration of valuable metals, in the treatments residue, to a reasonable value. Most of the solids issued from these treatments can be recycled in .the current non-ferrous metallurgical processes.

Jan 1, 1995

By L. I. Rosato

A novel hydrometallurgical process for the recovery of silver and gold from neutral leach residue that is based upon leaching with thiourea, is described. Laboratory and pilot plant studies have shown that 80-90% of the silver and 60-70% of the gold can be recovered by:? ( i) leaching zinc calcine with &apos;Spent electrolyte at pH 2.0-3.0 to generate a precious metal-bearing zinc ferrite residue, (ii) leaching of the thickened zinc ferrite with 3-5 g/L thiourea in a six stage carbon-in-pulp circuit, (iii) elution of silver and gold from the loaded carbon with a thiourea- butanol solution, (iv) thermal regeneration of the stripped carbon and (v) recovery of the precious metals from the pregnant eluate by cementation with zinc dust. The reasons for adopting the thiourea CIP leach and the preferred operating parameters for each process step are presented. The requirements for the destruction of any thiourea transferred to the zinc circuit are outlined, and the results of an integrated one tonne/day pilot plant operation at Canadian Electrolytic Zinc are given.

Jan 1, 1990

By D. M. Hausen

Applications of process mineralogy to the exploitation of molybdenum ores begins with early exploration and continues through the evaluation of mineralized prospects, to amenability testwork and pilot plant studies, to the development of a mineable orebody and to the development of a viable process for recovery. After plant construction, a broad range of products from a wide selection of sampling locations, i.e. grinding circuit, flotation cells, smelters and roasting kilns. etc., are evaluated analytically and microscopically, followed by periodic troubleshooting of problem points. The various crystalline phases of molybdenum that occur naturally and throughout various hydrometallurgical and pyrometal1urgica1 processes are identified and characterized by a variety of instrumental methods, including XRD-XRF, optical and electron microscopy, infrared spectrographic and differential thermal analysis.

Jan 1, 1989

By Richard B. Diver, Mark D. Allendorf, Daniel E. Dedrick, James E. Miller, Roy E. Hogan, Andrea Ambrosini, Eric N. Coker, Anthony H. McDaniel, Nathan P. Siegel, Gary L. Kellogg

"Converting carbon dioxide and water to hydrocarbons is an attractive option for storing solar energy and, coupled with appropriate CO2 capture technology, for recycling carbon and impacting atmospheric CO2 concentrations. For any process, high solar-to-fuel efficiency is necessary for large scale viability and favorable economics. Thermochemical approaches for solar-to-fuel conversion are potentially highly efficient as they avoid the inherent limitations of photosynthesis and also sidestep the solar-to-electric conversion necessary to drive electrolytic reactions. Solar-driven two-step metal-oxide-based thermochemical cycles for producing the components of syngas, CO and H2, from CO2 and H2O are the basis of the “Sunshine to Petrol” project. Multi-cycle production of both H2 and CO has been demonstrated over several iron- and cerium-based compositions fabricated into monolithic pieces both in the laboratory and at the National Solar Thermal Test Facility. These compositions are being developed for deployment in a unique and continuous solar-driven reactor prototype, the counter-rotating-ring receiver reactor recuperator or CR5.IntroductionThe interconnected challenges posed by increasing global competition for petroleum and the increasing concentration of atmospheric carbon dioxide are now widely recognized. Meeting these challenges requires recognition that although hydrocarbon fuels are ideal energy carriers, they can no longer be thought of as primary energy sources. It is necessary to take the realistic view that our conventional fossil fuels are in fact “stored sunlight” in the form of “sequestered carbon.” This view leads to a search for options to use and store sunlight more directly.Sunshine to PetrolIn combusting hydrocarbons we unlock the energy for utilization, but we also release the carbon to the atmosphere. However, nature teaches us that with an appropriate persistent energy source, e.g. solar irradiation, it is possible to effectively reverse the combustion process and “reenergize” CO2 and H2O back into hydrocarbon form."

Jan 1, 2010

By V. Jiricny

There is a growing need to process galvanized steel scrap from automobiles, etc., in order to remove the zinc coating that otherwise causes problems in remelting of the scrap in electric arc furnaces. One approach that has moved to the pilot plant stage is that of Metal Recovery Technologies, Inc., of East Chicago (MRI). That company leaches the zinc fiom the scrap with a sodium hydroxide solution. The leached and washed scrap can then be returned to the steel industry. What is left is a sodium hydroxidelzincate solution which must be processed to recover the zinc and the NaOH. Presently, this is done by MRI using electrodeposition on planar electrodes at moderate current density and the resulting zinc is in the form of fine powder which is hard to process into, say, zinc for galvanizing. MRI has supported an investigation of a novel electrode, the spouted bed electrode (SBE), for zinc electrodeposition. In laboratory cells, zinc particles with low porosity have been grown up to 3mm in size. Microanalysis of the deposited zinc showed low level of impurities. DC energy consumption values were usually in the range of 2-2.5 kWg which is well below the energy consumption of the existing cells (and of present-day cells for electrowinning from acid sulfate electrolytes). These results were achieved at current densities (few thousand A/m2) that are much higher than possible with conventional electrodes. Discussion is provided of the scale-up of the cell to a commercial scale.

Jan 1, 1998

By Richard D. Hagni

The techniques of reflected light microscopy and cathodoluminescence microscopy are uniquely suited to the study of the products from many important industrial problems. Ref1 ected 1 ight microscopy provides the means to rapidly identify the mineralogy of an industrial sample, determine the abundance of each phase, and examine the mineral intergrowths or textures. Cathodoluminescence microscopy is a relatively new instrument that provides the means to cause many minerals to cathodoluminescence under the microscopy. The cathodoluminescence of a mineral allows it to be readily distinguished from other phases that differ in cathodoluminescence but are similar in optical properties. Cathodoluminescence microscopy is especially useful to detect cathodoluminescence minerals that are present in only small quantities. Reflected 1ight microscopy and cathodoluminescence microscopy have been successfully applied in studies of beneficiation products, prediction of beneficiation and leaching problems, phosphatic iron ores and mill products, pyrometallurgical products, roasted refractory gold-bearing sulfides, ceramic build-ups, electric arc furnace and smelter dusts, and other industrial products.

Jan 1, 1993

By Mukesh K. Agarwala

Alloy composite parts were made from powders by Selective Laser Sintering (SLS). SLS is a rapid prototyping process that uses data from CADICAMICAE systems to guide a laser beam and rapidly form 3-D prototype parts from powders without any part specific tooling. In this study, Bronze-Nickel parts made by SLS were studied for their mechanical properties. To make the parts structurally sound, SLS parts were further processed by conventional isothermal sintering, without loss of shape. The resultant densification and mechanical properties were studied and related to microstructures and P/M densification models. These results were then correlated to the SLS processing parameters.

Jan 1, 1994

By Qingchun Yu, Baoqiang Xu, Yongnian Dai, Bin Yang, Fulong Zhu

"In this paper, the mechanism of the carbothermic reduction-chlorination process to extract aluminum from alumina in vacuum was investigated. The carbon monoxide (CO) content of the gas, phases of the reduction slag, surface morphology of the reduction slag and the product aluminum were measured by means of gas chromatography (GC), XRD, and SEM. The experimental results indicated that the content of CO in the gas decreased, but Al4C3 increased with time at 1773K during the carbothermic reduction process of alumina. AlCl(g) and graphite (C) were produced by the reaction between Al4C3 and AlCh(g) at 1773K, and then aluminum beads generated after the decomposition of AlCl(g). It implied the mechanism of alumina carbothermic reduction-chlorination process in vacuum involves three steps as follows: the carbothermic reduction of A}z03 to produce Al4C3, the chlorination of Al4C3 by AlCh(g) to produce AlCl(g), and the decomposition of AlCl(g) to produce Al(l).IntroductionAluminum is the basic raw material for many industries [1], and it is used extensively because of various excellent properties such as light weight, good malleability, high strength, excellent thermal conduction, high corrosion resistance and so on [2]. Industrial production of aluminum currently includes refining alumina and electrolytic aluminum processes. However, its development has been effected by some factors such as high energy consumption and heavy environmental burdens [3]. In the past several decades, there had been numerous attempts to produce aluminum by new methods. Extracting aluminum from alumina or bauxite directly by carbothermic reduction-chlorination process had been studied [ 4-6]. Although the alumina carbothermic reduction process [7~9] had been studied, the mechanism of the carbothermic reduction-chlorination process had not been systematically elucidated.In order to investigate the mechanism of the carbothermic reduction-chlorination process in vacuum, GC, XRD and SEM techniques will be used to determine the CO content and to characterize the surface morphology and composition of the slags at various temperatures."

Jan 1, 2011

By P. N. Anyalebechi

The effects of application of steady and pulsed electric current on the cast microstructures of ingots of a 7050 type aluminum alloy have been experimentally investigated over a solidification rate range of 0.1-10 K/s. This involved the application of an electric current of 465-930 mA/cm2 of melt surface area to laboratory-size ingots solidified in a unidirectional manner. Within the ranges of electric current density and solidification rate investigated, the applied electric current reduced the average dendrite, grain, and second-phase particle size. It also made the size distribution of the second-phase particles more uniform. The mechanism for the observed refinement of the cast microstructure by the applied electric current is not well understood. The potential effects of heat-induced local convections, shear stress-induced fragmentation of dendrites, increased temperature gradient due to Joule heating and the thermal and constitutional supercooling engendered by Peltier, Thompson, and Joule heating are discussed.

Jan 1, 2009

By E. Oshima

The only one reverberatory furnace smelting in Japan has been alive in Onahama Smelter, Onahama Smelting and Refining Company. The fuel for the reverberatory furnaces had been changed from bunker C-oil to mainly coal and partially waste tires to reduce the energy cost. The steam, recovered by the waste heat boilers of the reverberatory furnaces, has been utilized fully for the power generation to save the purchase power. Copper concentrate has been smelted also by injection through tuyeres in the P.S. converters since 1983. The amount of concentrate, treated in the converters, was increased by the construction of small oxygen plant in December, 1990. In the paper, the current practice and improvements in the reverberatory and converter operations are described.

Jan 1, 1993

By C. Takano

The integrated iron and steelmaking industry generates large amounts and many types of solid dusts and sludge, at different phases of the production. Within these are: sludge of the Blast Furnace; coke fines; fine and coarse fractions from oxygen converters; sludge from water treatment at rolling mill unit; and others. In this paper the above dusts and sludge were physically and chemically characterized. The obtained results allowed defining self-reducing pellets using these materials. The high temperature behavior of the pellets were evaluated. Good results, with no decrepitation and swelling, and high yield of reduction, show that it is feasible to recycle them, as self-reducing pellets, in oxygen steelmaking converter.

Jan 1, 2001

By H. Y. Sohn

"The nonferrous production industry has gone through a remarkable transformation in recent years in terms of developing and adopting new technologies. Technology innovations have largely been driven by the need for greatly improved environmental protection in addition to increased productivity. One of the most notable aspects of the new technologies is their ability to reduce the emission of sulfur and other pollutants to extremely low levels.The current industry trends towards more environmentally friendly technologies are bringing about additional benefits of developing more efficient, technically advanced, and continuous processes in closed reactor vessels. Key aspects of these modem trends include the use of increased oxygen enrichment in the process gas, better process control, reduced manpower requirements, and plant operations with more skilled personnel.Computer simulation and modeling of complex processes have become more reliable, realistic, and thus increasingly useful in metal production. Some of the notable examples are reviewed.Finally, the need and advantages for value-added production in the nonferrous industry are discussed.I. IntroductionMost recently commissioned technologies for nonferrous metals production have been developed largely in response to environmental concerns. One of the most remarkable improvements made by the nonferrous industry in the last decade has been the rapid increase in sulfur capture. Before the start of the last decade, 90% capture of sulfur was considered good. Since then, strict emission regulations have become the norm in advanced societies, although smelters in many parts of the world still operate with limited pollution control. Other emissions and discharges have also been substantially reduced, resulting in much improved working conditions and worker hygiene in addition to the overall environmental protection. The development of the more environmentally friendly technologies has accompanied other advantageous advances made in the nonferrous industry, i.e., the trend towards more gas-tight, continuous processes and larger plants. This has increased the competitive edge enjoyed by the industry in the industrial countries, offsetting the higher costs of labor and pollution abatement that they have to overcome in those countries. Experience has shown that clean technology often leads to a profitable business, because its adoption forces the concomitant advancement of related technologies in addition to the avoidance of penalties imposed by the public on pollution-prone industries. Needless to say, there are other driving forces for new technologies such as reduction of operating and capital costs, improved product quality, and energy considerations in terms of reduced consumption and utilization of readily available sources."

Jan 1, 2000

By A. M. Strachan

Capper Pass & Son Limited Was, until its recent closure, the world&apos;s largest producer of tin from secondary materials including solder drosses, non-ferrous smelter flue dusts, tin based metal alloys, residues and slags. Polonium-210, an alpha emitting radionuclide, was present in varying concentrations in some of the numerous feed materials processed by the smelter and refiner. The polonium-210 followed a complex path through the process flowsheet. This paper discusses the behaviour of polonium, both from its arisings in other smelters&apos; process streams and through the entire Capper Pass smelting and refining circuit. The consequential personnel safety and environmental precautions necessarily taken in some areas of the process operation are outlined.

Jan 1, 1992

By D. L. Yopps

Platinum-group metal (PGM) flotation .. concentrate from the Stillwater Complex, MT, was subjected to biooxidation using Thiobacillus ferrooxidans in an effort to break down the sulfide minerals and liberate the ? associated PGM&apos;s for subsequent chemical leaching. Bacterial treatment oxidized up to 94 pct of the sulfide present, destroyed the PGM-bearing pentlandite [ (Ni,Fe),9Ss) mineralization, and dissolved most of the nickel in the concentrate. Results showed that increased sulfide oxidation during the biological stage led to improved PGH recovery in the subsequent. chemical leaching stage. cyanidation at 80° c proved to be the best chemical leachant tested. It removed 7.6 pct of the palladium, 94 pct of the rhodium, 97 pct of the gold, but only 34 pct of the platinum from the biooxidized concentrate.

Jan 1, 1991

By Donghai Li, Cheng Pan, Pan Chen, Xuewei Lv, Mei Liu

"Chromite concentrate after beneficiation can not be directly used in the electric furnace. Therefore sintering is one of the effective way to agglomeration, by which the chromite concentrate can be utilized and the power cost of ferrochrome smelting can be reduced. The properties of raw materials and the sintering process of chromite concentrate were studied in this work. The results showed that chromite concentrate used can hardly granulated alone, while chlorite addition can improve the effect of granulation. Moisture plays an important role in sintering process. The granulation effect is optimal when the amount of water addition is 12%. Strength and abrasion index are the evaluation indexes of sinter quality. It was found that the strength of sinter increased with coke dosage increasing to 12%, and then decreased when it continuously increased. Opposite regularities were found for the abrasion index of the sinter.1 IntroductionChromium is a very important metal element which is mostly used in the production of stainless steel. In the earth, it is always formed compound with iron as ferrochromium spinel (FeO.Cr203), and its mineralogical name is chromite.[1] Currently, the global production of chrome ore is about 20 million tonnage every year , in which fine ore (less than 8 mm) accounted for about 80% [2] Although the price of the fine ore is cheaper than the lump one, too much fines will lead to the poor permeability and causes increased electricity consumption while producing ferrochrome. Therefore, the agglomeration process of chrome ore is one of the effective measures to increase the usage ratio of fine ore."

Jan 1, 2013

By Sabine Knott

The thermodynamic properties of four liquid ternary zinc alloys, Au-Sn-Zn, Ag-Sn-Zn, AI-Sn- Zn and Cu-In-Zn were measured with an electromotive force (emf) method at three or four cross-sections with an constant X:Sn or Cu-In ratio. At the Au-Sn-Zn and AI-Sn-Zn system calorimetric measurements were also carried out in order to compare the integral enthalpy of mixing from the direct measurements with the data of the emf measurements, which were derived by Gibbs-Duhem integration.

Jan 1, 2003

By U .. C. Rojas, J .. C. Gomez

"Fire Refined Copper (EI Teniente Three Stars) has been produced at Caletones Smelter of Codelco Chile since almost the beginning of its operations.Due to changing features of the copper market, together with the targets on technical efficiency and productivity, it has become more and more relevant for copper industry to reach both, good final product quality and a proper environmental control.At present, copper refining process at Caletones Smelter takes place in two cylindrical tilting furnaces, where solid fluxes are injected through horizontal tuyeres into the molten bath. (Fig. N2 1)Solid reagents are pneumatically conveyed and injected into the liquid copper bath attaining excellent solid - liquid contact, so the impurities removal efficiencies are found to be high. Same injection tuyeres are used to introduce both oxidising agent (normal air) and reducing agent (reformed gas) into the molten bath. Air or nitrogen is used as conveying gas for solid reagents, depending on the process stage.This pap~r gives a fundamental description of the process and industrial results related to the injection of blend of sodium and calcium carbonates to remove arsenic and antimony, silica and granulated reverberatory slag to remove lead and a mixture of calcium carbonate and mineral coal to reduce the selenium content of the fire refined copper."

Jan 1, 1996