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By Yanhui Liu, Xuewei Lv, Chenguang Bai

A thermodynamic model for determining the surface tension of molten slag by considering the surface tension and molar volume of the pure oxide component, and their ionic radii was extended to the slag bearing high TiO2 (varying from 80 to 67%) at 1973 K. The iso-surface tension curves for the FeO-TiO2-Ti2O3 ternary system at 1973 K are almost parallel to the FeOTi2O3 line. TiO2 plays a role of surface-active solute, and its surface-active effect is attenuating with increasing the TiO2 content. The iso-surface tension curve shifts away from the TiO2 corner, indicating that the surface tension of the ternary slag decreases along with the addition of SiO2. The reasons include the addition of SiO2 with lower surface tension and the decrease of the total ion moment at the surface. Both CaO and MgO can bring about that the iso-surface tension curve shifts towards the TiO2 corner, indicating that the surface tension of the ternary slag increases along with the addition of CaO or MgO. CaO has a more pronounced effect on increasing the surface tension of the ternary slag than MgO at an equimolar amount addition. The increase of the surface tension results from both the compositional change and the variation of the slag structure.

Jan 1, 2015

By Robert D. Rogers

The demand for phosphate will continue into the future, because phosphate is currently irreplaceable as a plant nutrient and in many chemical applications. Phosphate is not recycled, so the supply must be replenished through a process of mining and purification. Numerous microbial isolates. obtained from the environment were screened find those which demonstrated the greatest promise of solubilizing PO4 from the ore of interest. Screening was accomplished in a step wise manner an agar plate bioassay, shake flask studies, and semi continuous growth conditions. It was found that with the proper conditions of nutrient supply and solution pH; the bacteria and. fungus used in the semicontinuous process were able to solubilize in excess of 80% of an Idaho rock phosphate ore (RP) within nine days. A significant amount of solubilization occurred within the first six days. There was a 'reasonable correlation between the occurrence of soluble Ca and PO.4 during the processing of the RP thus providing evidence that the RP was being disintegrated by the organisms. In all cases, HPLC analysis of the solutions in which PO4 had been. extracted from RP showed that organic acids, which have been implicated as the mechanism of solubilization, were present.

Jan 1, 1991

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 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 Run-sheng xu, Hai-yang WANG, Di ZHAO, Teng-fei SONG, Jian-Liang Zhang

This paper was mainly focused on the different semi-cokes and charcoal which could be new fuels for blast furnace injection. Through the comparative study with bituminous coal and anthracite coal, the properties of semi-cokes and charcoal were presented in this research. 10 indexes of different fuels were obtained by different standard experiment, including proximate analysis, ultimate analysis, igniting point, explosivity, transportation characteristic, ash properties, grindability, calorific value, combustibility and reactivity with CO2. According to the data analysis, it provided a theoretical basis for rational utilization of various blast furnace fuels, and helped to broaden the scope of the blast furnace injection fuels. This research could contribute to energy conservation, emissions reduction, and sustainable development of iron and steel enterprises.

Jan 1, 2015

By Baptiste Laubie

Agromining is a phytotechnology aiming at producing commercial metal compounds from low-grade ores thanks to hyperaccumulating plants. The fern Dichranopteris dichotoma is a rare earth element (REE) hyperaccumulator, which naturally grows on former mine tailings in China. It accumulates up to 0.35% of REEs in its aerial parts. Different hydrometallurgical processes are currently developed to recover these elements directly from the biomass or from ashes after combustion. The process presented here consists of a direct extraction by EDTA solution, followed by precipitation with acid oxalic. Optimal precipitation pH and influence of organic matter are determined by modelling and by experimental studies. The final solid contains 4.3% of REEs, with calcium as the main cationic impurity (0.45% of the precipitate). The recovery yield is similar for major REEs and is around 70%. After optimization, upscaling of the process will allow the agromining development to recover REEs from secondary resources with more environmentally friendly techniques.

By M. E. Myers

An experimental program is being carried out to determine the thermodynamic characteristics of zinc solubilization in high-temperature iron and iron-carbon alloys. Two versions of an isopiestic technique are being used, with zinc at a lower temperature being equilibrated with pure iron foils or molten iron-carbon alloys at a higher one. The lower temperature sets the partial pressure of zinc vapor, and thus the activity relative to a given reference state. Initial results show Henrian behavior for dilute zinc solutions in austenite and a molten 4.6% C alloy, with unit-pressure solubilities in pure Fe that closely match the predictions of Wriedt.

Jan 1, 1992

By Dinesh P. Amalnerkar, Nagegownivari Munirathnam, Tirthalli Prakash, Katia Vutova, Vania Vassileva, Veliko Donchev

"A time-dependent model for electron beam melting and refining (EBMR) of different metals and alloys is developed. The model is 3D axi-symmetrical and an adapted numerical scheme of Pismen-Rekftord type is applied. The developed computer program computes the thermal fields in the metal ingots during EBMR process as well as the dynamics of the thermal streams and the geometry of the molten metal pools. Calculated results for different regimes of EBMR of titanium are obtained and discussed in the paper. Experiments are performed and impurities' concentration data are presented. Simulation results are compared with experimental data and are used for optimization of the EBMR process in the case of Ti.IntroductionElectron beam melting and refining (EBMR) has an important role in the special electrometallurgy[ 1-6] and it is approved for obtaining of pure titanium [7]. EBMR of metals and alloys is being recognized as a competitive and even the single method for obtaining new materials for all areas of human activity.The principal scheme of the EBMR drip process is shown in Fig.1. A thin layer of molten metal is formed on the front part of the feeding rod during the e-beam processing and generated droplets fall into the molten pool in the crucible where the ingot is formed. The refining is mainly realized at the boundary liquid metal - vacuum. There are three zones in EBMR (Fig.1) - on the front part of the feeding rod (zone I in Fig.1 ), on the surface of the generated droplets (zone II in Fig.1) and the surface of the molten pool in the water-cooled copper crucible (zone III in Fig.1)."

Jan 1, 2013

By Gabriel Plascencia

Copper was oxidized in the temperature range from 300 to 1000 °C under different pressures of oxygen, In the range from 300 to 500 °C, copper oxidizes following the logarithmic rate law; while in the range from 600 to 1000°C oxidation follows the parabolic rate law. Transition from logarithmic to parabolic growth occurs at about 525°C. X-ray diffraction was performed on oxide scales to account for the CuO/Cu2O ratio at different temperatures. Activation energies found in this work are in good agreement with reported values.

Jan 1, 2003

By Gabriel Plascencia

Copper was oxidized in the temperature range from 300 to 1000 GC under different pressures of oxygen. In the range from 300 to 500°C, copper oxidizes following the logarithmic rate law; while in the range from 600 to 1000°C oxidation follows the parabolic rate law. Transition from logarithmic to parabolic growth occurs at about 525°C. X-ray diffraction was performed on oxide scales to account for the CuO/Cu2O ratio at different temperatures. Activation energies found in this work are in good agreement with reported values.

Jan 1, 2003

By T. Shibaraki

A new larger, more efficient and economical Mitsubishi furnace line at Naoshima was put into operation in May 1991. Naoshima Smelter had produced previously about 230,000 mtpy anode copper with two smelter lines, i.e., a conventional reverberatory furnace line and Mitsubishi furnace line, which had been shutdown at the same time of the start up of the new smelter. At the beginning of the operation, there were several initial problems at the area of off gas trains and feeding system. By overcoming them now the process has been continuing satisfactory operation at the design rate. The paper describes about the design concepts and the actual operation of the new smelter.

Jan 1, 1993

By Honglei Zhang, Wuguo Xiang, Xinhao Huang, Guotao Xu, Xilai Chen

"The service behavior of refractories used in hot air pipeline for hot air stoves in a 3200 M3 blast furnace of WISCO was analyzed. The damage factors can be concluded as the poor quality of and alusite based bricks, the severe thermal shock damage, the more porosity in structures, loose bonding capability, and the unreasonable choice of materials and design of bricks. By analysis, the service life of hot air stoves can be enhanced by the measurements such as the reasonable choice of materials and their match, the use of light-weight refractories, the improvement of brick type, etc. Thereafter, the normal production operation of hot air stoves is guaranteed.IntroductionThe No.7 blast furnace of WISCO has been used for about 5 years and it was mid-repaired in March, 2012. The top phenomena of worn hot air pipelines are brick drop, breakage, severely local wear and deformation, existing hidden danger, so the worn hot air pipelines were renewed. Investigations have been done on the stove damage and design [1,2]. In order to clarify the wear mechanism, the used refractories for hot air pipelines were sampled and analyzed, the properties and structures of worn materials and reused materials are relatively studied."

Jan 1, 2013

By Ryosuke O. Suzuki

A new cell concept for calciothermic reduction is proposed in which the titanium dioxide instead of TiCl4 is used as the raw material for reduction, Metallic calcium is needed as the reductant of a thermochemicaily stable oxide, such as TiO2. CaCl2, is selected as the solvent of Ca and simultaneously as the solvent of CaO. The reduction system consists of a single cell where both the reduction reaction and the electrolytic reaction for recovery of reducing agent coexist in the same molten CaCl2 bath. A few mol%Ca dissolves in the melt and gives the media a strong reducing power. Sufficiently deoxidized metallic titanium deposits and forms a slightly sintered granular sponge. Both mechanisms of the halide flux deoxidation and the electrochemical deoxidation work efficiently for these fine precipitates, The reducing agent is in situ recovered by electrolysis of CaO because the molten CaCl2 he a relatively large solubility for CaO Some cell designs and modifications are proposed for industrial applications.

Jan 1, 2003

By George Oprea, Tom Troczynski, Joe A. Rigby, Waiman Lo

The refractory lining of the tuyere line in Peirce Smith converters have usually much shorter life in service than the rest of the lining, above or below it. There are already recognized chemical, thermal and mechanical factors which contribute to the wear of the lining. Our study presents the experimental results on microstructural changes occurring on these tuyere line bricks in a nickelcopper converter. The experimental bricks, after use at the tuyere line, were investigated using SEM/EDS and XRD techniques, to identify the mineralogical changes due to interactions with the nickel-copper matte or fayalite type slag at the process temperatures. The microstructural changes were correlated with physical and mechanical properties of the brick before and after use and a wear mechanism was suggested. Although the matte does not theoretically react with the mineralogical components of the brick, a partial oxidation of the Ni-Cu sulphides was identified using a line analysis by SEM/EDS in the densified layer at the hot face, which allows for mineralogical changes at the matte-refractory interfaces, with a high probability of microcrack formation due to the thermal cycling during use. These microcracks were also identified to open through inter-granular fractures parallel to the hot face, which appeared to be the main cause of lost lining during use. The reactions between the fayalite slag and refractory brick could eventually play a role in chemical dissolution of the brick only in the superficial layer at the hot face, as no slag components were identified deep into the brick.

Jan 1, 2009

By H. Y. Sohn, S. PalDey

"A new chemical synthesis process for the preparation of intermetallic compounds has been developed. It involves the vapor-phase reduction of mixtures of constituent metal chlorides by magnesium vapor to produce intermetallic compounds in the form of fine powder. The advantages of the process include (a) the use of inexpensive raw materials, (b) low reaction temperatures, and (c) products in the form of fine particles. Titanium and nickel aluminides were prepared by this method. The effect of AlCl/TiCl3 partial pressure ratio on the formation of different titanium aluminides was studied. A two-phase mixture containing 80 mol % of TiAl and 20 mol % of TiA13 formed at an AlC13/TiC13 ratio of 10. The amount of TiA13 was maximized to 72 mol% at an AlC13/TiC13 ratio of 16. The maximum conversion of the limiting chloride TiCl3 was 94 % . In the case of nickel aluminides, NiAI, NiAl3, and Ni2Al3 were formed by reducing mixtures of NiC12 and A1Cl3 vapors. The effect of the partial pressure ratios AlCl3/NiC12 and Mg/NiC12 on the formation of nickel aluminides was studied. The maximum content of NiAl obtained was 98 mol % . At the AlC13/NiC12 ratio of 19, a two-phase mixture of 17 mol% of NiAl and 83 mol% of NiA13 was produced. The product particles were very fine in the size range of 0.05 to 0.2 µm.A. IntroductionIntermetallic compounds are attracting much attention [1]. Titanium and nickel aluminides have attracted a great deal of attention from the aerospace as well as automobile industries because of their potential for high-temperature application (e.g., low density, good oxidation resistance, and high-temperature strength retention [2, 3]). Gamma TiAl and two-phase (TiAl and Ti3Al) alloys [4] are used for gas turbine engine rotational components as well as automobile exhaust valves. TiAl3 is one of the most extensively investigated aluminum-rich intermetallics. Nickel aluminides are attractive because of their low densities, relatively high melting point and good high-temperature strength properties. For example, Ni3Al shows increasing rather than decreasing yield strength with increasing temperature [5]."

Jan 1, 1998

By K. Robinson

Following the longest Smelter campaign in BCL?s history it was planned to completely rebuild the flash smelting furnace in 1987. This was the fourth major overhaul and the most extensive so far attempted. Detailed planning took place over several year$ preceding the shutdown and implementation was completed in 54 days. The key to minimising shutdown time was the method designed for installation of the new uptake shaft and reaction shaft. Major repair work was also undertaken in the waste heat boiler and electric furnaces. Both of these activities had an impact on the critical path of the flash smelting furnace overhaul.

Jan 1, 1993

By B. Thompson

"1. AbstractMagnesium alloys have been successfully recycled for decades and have won acceptance for use by die casters and most of the automotive industry. As the supply chain for magnesium and magnesium alloys continues to change, due to the consolidation of producers, it is essential that quality control methods be closely examined with each new supplier added. An examination of the various process steps that are needed to assure quality in the final product will be discussed thus giving a basis for the auditing of new magnesium suppliers.2. IntroductionMagnesium recycling in the past has been somewhat limited due to its use more as an alloying agent for aluminum based alloys and as a desulfurization agent in iron and steel than in more readily recycled structural products. Recycling efforts continue to improve as more production is finding its way into automotive structural components, hand tools, and a variety of computer and cellular telephone applications.With the closure of several large North American primary magnesium production facilities over the past decade we have only recently witnessed a tightness in supply that is driving magnesium prices significantly higher, nearly doubling the price in the last year alone. The rapid escalation in pricing will provide additional economic incentives to fully utilize recycling for the recovery of an even greater percentage of both old and new sources of magnesium scrap. Political pressure continues to intensify towards the secondary recovery of any and all recoverable resources of which magnesium recycling readily applies.Economics will also likely drive the development of new sources of magnesium production, both from primary and secondary production. As new sources of magnesium are offered to the marketplace the potential for product quality issues may increase. When considering any new raw material supplier a decision must be made as to the impact of defective material on the intermediate or finished product. Quality defects in magnesium ingot can result in a variety of appearance, corrosion, and even adverse structural effects in the finished product. The potential severity of the impact of defective raw materials on the finished product will determine and often justify a close look at any new supplier. An on-site audit of a new supplier of a critical raw material is often justified to ensure that an adequate quality assurance system is in place. We will now look at a number of key production points that should be examined during an on-site audit that have can have an impact on the overall quality of the finished product."

Jan 1, 2008

By M. Cloete, C. MacLagan, A. Newall

This paper initially gives a brief overview of Zinc Corporation of South Africa Limited (Zincor). The original design parameters of the Zincor roasters are compared to the current operation, and the requirements for efficient roasting are listed. Roaster operational problems experienced during the early to mid 1990's are outlined. A description of the investigation and the outcome to increase overall roaster availability are given. The history and the development of the use of oxygen at the Zincor roaster operation, with an account of the associated operational experiences, are explained.

Jan 1, 2000

By Charles L. Richman

The effect of the addition of Silver Sulfide on the rate of Chalcopyrite (CP) of Sulfuric acid (H2SD4 leaching is discussed, Although Ag2S in an expensive addition, a theoretical explanation of it's use will aid in the development of a economic substitution. We have used cyclic voltammography to show the presence reaction species at different potentials. Cyclic Voltammography maps the surface reaction current peaks on CP, to regions on the CP Phorbaix diagram. AC Electro-lmpedance spectroscopy (EIS) models the surface impedance properties, which control the rate of electron and ion transfer, and the surface kinetic reactions, with and with out light. EIS and other measurements show that AgCuS u Photo-reactive material- The EIS results are compared with the SEM and EDXA results to show the presence of diffusion pores, and diffusion controlled reactions during CP leaching without the addition of silver sulfate. We hypothesize that AgCuS is an ionic conductor like Ag2S. EIS shows an imposed negative leaching rate greatly. Our theory shows how the formation of Silver Copper (1) sulfide layer at open circuit potential gives an effect similar to negative potential, that is enhanced with illumination. We verify that AgCuAS is an N-type semiconductor that forms a diode type junction with the electrolyte with the Mott-Schoottly relation.

Jan 1, 2001

By Krishna Parameswaran

This paper discusses sustainability considerations in primary copper smelting using selected examples of practices at ASARCO LLC, an integrated U.S. primary copper producer. Using the classic Brundtland Commission definition of sustainable development, i.e., “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper discusses how copper mining and smelting practices can be made sustainable. The examples used to illustrate sustainability considerations include: (1) adoption of flash smelting; (2) emission reduction and process improvement associated with anode refining of blister copper and the converter retrofit project, and (3) preliminary research findings on alkali treatment of copper smelting slags and copper mine tailings.