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By M. K. Mohan

During the processing of metals like Cu, Ni, Co, large quantities of solutions, which contain co- products such as Sb, Cd, Pb etc. are generated. These solutions if processed to recover the metals help in conservation of metals as well as environment preservation. The present study was taken up to recover antimony from process solutions using zeolites. The effect of pH of the solution, time and type of zeolite viz., chabazite, mordenite, erionite and clinoptilolite on the sorption of antimony was investigated. Rate of sorption increases with pH and about 77-pct. antimony sorption was observed with chabazite at a pH of 6. Optimal conditions were established for the maximum recovery of antimony fiom process solutions. The mechanism of sorption for Sb was proposed in terms of adsorption and intraparticle diffusion. The calculated adsorption constants from Langmuir and Freundlich equations indicated that the adsorption of antimony on chabazite was strong.

Jan 1, 1999

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 Vaughan R. Voller

"Solidification systems from conduction controlled freezing of a pure material through to alloy phase change that include flow and segregation processes are described. The components in a general solidification model-variables, governing transport equations, and local scale relationship-are outlined. A central focus is the presentation of an explicit procedure for coupling between macroscopic and local scale variables.IntroductionSince the seminal work of Byres et al.[!] in the 1940's there has been a steady progress in modeling solidification systems with increasing levels of complexity. The object of this paper is to track the evolution of these solidification models and present a general modeling approach that applicable to a wide range of the solidification systems of current interest.Solidification SystemsIn a broad sense the underlying physics in a solidification process occur at two distinct length scales:1. The macroscopic scale of the process over which the governing transport equations of heat, mass and momentum hold.2. The local scale at the solid-liquid interface where the solidification phenomena are operative."

Jan 1, 1999

By Bora Derin

The partial pressure ratios of sulfur and oxygen for several copper flash smelting plants were derived using the Reddy-Blander (RB) model and predicted dissolved sulfur contents available in the literature. The sulfide capacities (Cs) of six different flash smelting plants (FeO-CuOo.5- CaO-MgO-FeOu-AlO15-SiO2) slags were calculated. The log (PO2/PS2) versus matte grades of various industrial processes was determined. The PO2/PS2 ratio increased with an increase of copper grade. The calculated partial pressure ratios for the copper flash smelting are in good agreement with those of the experimental data.

Jan 1, 2003

By Giulio R. Altoé, Sergio N. Monteiro, Ygor M. Moraes, Rômulo L. Loyola, Frederico M. Margem, Gabriel O. Glória

The tensile properties of DGEBA/TETA epoxy matrix composites reinforced with different amounts of PALF fibers were evaluated. Composites reinforced with up to 30% in volume of long, continuous and aligned PALF fibers were tested in an Instron machine at room temperature. The fracture was analyzed by SEM. This one revealed a weak fiber/matrix interface, which could be responsible for the performance of some properties. The results showed significant changes in the mechanical properties with the amount of PALF fibers.

Jan 1, 2015

By M. D. Stephens

A new, one-step process for extracting titanium from titaniferrous materials has been demonstrated. In the process, depleted uranium tetrafluoride (DUF 4), a solid, is mixed with ilmenite (FeTi03) and heated to 900°C. Titanium is extracted in the vapor phase as titanium tetrafluoride (TiF4) and the DUF4 is converted to uranium-iron oxide. The process has been found to selectively fluorinate the titanium in ilmenite and is capable of producing high purity TiF 4 with very low iron content. TiF 4 can be collected by condensation or through reaction with a fluoride salt such as NH4F, KF, or NaF. The TiF4 produced from the process can be used to make titanium metal, titanium oxide, or fluorotitanate compounds. Since the fluorination process is highly selective for titanium, it avoids many of the separations and waste issues common to other titanium extraction processes.

Jan 1, 2001

By K. M. Parida

The kinetics of dissolution of manganese dioxide in dilute sulphuric acid solution have been investigated using iron pyrites as a reductant. The dissolution rate of manganese is independent of the speed stirring but depends upon temperature, particle size, specific surface area of manganese ore, acid concentration, Fe(II) concentration and amount of pyrite. The activation energy is 43.6 KJ/mol and the linear relationship between the rate of dissolution and lido indicates that the reaction is chemically-controlled. The redox reactions of MnO2 with iron pyrites and Fe(II) are the rate-controlling reactions.

Jan 1, 1990

By B. Wasmund, K. Adham, K. O'Keefe, C. Lee

"Metal chlorides (e.g. iron and nickel) can be pyrohydrolysed at elevated temperatures to yield an HCl rich off-gas and a metal oxide product. Typically, the high energy requirement for pyrohydrolysis is provided by the combustion of a hydrocarbon fuel with air. Here, it is demonstrated that the use of oxygen-enriched combustion can result in lower fuel requirements and higher HCl concentrations. In addition, the oxygen enrichment can result in a smaller volume of off-gas and thus, smaller and less expensive process equipment. This new concept can be applied to both the spray roaster (SR) and the fluidized bed reactor (FBR). Similar to the aircombustion case, the oxygen-enriched process can use a direct contact venturi scrubber, to recover energy from the roaster off gas, but at a higher efficiency. The new process also uses an absorption tower for capturing HCl from the roaster off-gas, but generates a stronger HCl solution than is possible with pyrohydrolysis in air.BackgroundIn recent years, the metallurgical industry has become increasingly involved with developing methods for extracting metals, upgrading products or cleaning metallic products by using hydrochloric acid. These applications of chloride metallurgy often result in metal chloride solutions, which should be processed to regenerate HCl for reuse, and to recover the metal value as a product or by-product oxide [2, 3, 4].The pyrohydrolysis of metal chloride solutions has been done in two types of air roasters: spray and fluidized bed. The existing roasters burn a hydrocarbon fuel in air, to provide the required energy for evaporating the feed solution and to provide an elevated temperature for the chloride pyrohydrolysis to occur, according to the following reactions:"

Jan 1, 2011

By Robert Mensah-Biney

The loading characteristics of gold-tetrabromide species onto a weak-base resin, PAZ-4, were evaluated using a completely mixed batch reaction system. The time. to attain equilibrium loading was substantial, on the order of several days. However, abnormally high loading capacity values of 15 to 20 meq Au/g dry resin (1000 to 1300 kgAu/tonne) were attainable in 24 hours. The loading of gold-bromo species by P AZ-4 was visualized as consisting of two processes: (i) the rapid adsorption of [AuBr4r species by simple ion exchange mechanisms and (ii) reduction of [AuBr4r to metallic gold by an electron exchange mechanism. Elution of gold from loaded resin was feasible provided the resin had not been loaded to high capacity values. If loading is carried to high levels, complete elution becomes impractical and the gold may be recovered by ashing the loaded resin. For the high loading capacities observed this option would appear to be cost effective.

Jan 1, 1991

Heap leaching with thiosulfate is only used in one location for the treatment of a refractory preg-robbing gold ore initially pre-treated with bio-oxidation. The chemistry of thiosulfate leaching is complex. Further work is required to develop a better control of the system. A mild refractory gold ore containing pyrite and chalcopyrite was used in this study to investigate the use of thiosulfate as an alternative heap leaching technology. Preliminary bottle rolls tests indicated that similar gold extraction was obtained with cyanide and thiosulfate. In the column leach test, effects of thiosulfate, copper and ammonia concentrations, and their ratio on both gold extraction and reagent consumption, were assessed. The range of reagent concentration were: 0.1 - 1.0M (NH4)2S2O3, 0.03 - 0.10M CuSO4*5H2O, 1.0 - 6.0M NH4OH. The solid-liquid ratio was in the range of 0.83:1 to 5: 1. Best results showed that 72% of gold was extracted in 50 days with 0.3M (NH4)2S2O3, 0.05M CuSO4*5H2O and 6M NH4OH or a combination of 1.0M (NH4)2S2O3, 0.03M CuSO4*5H2O and 3M NH4OH. The reagent consumption at solid/liquid ratio of 3:1 was 37 - 48.6 kg/t (NH4)2S2O3 and 0 - 0.62 kg/t CuSO4*5H2O. The results of thiosulfate leaching were also compared with cyanide leaching.

Jan 1, 1999

By Miguel Barron

Recently, a new lance design for BOF steelmaking has been proposed in the literature. This lance, in addition to six peripheral inclined supersonic nozzles, contains a vertical centered nozzle whose oxygen flow is independent from the main oxygen supply. The above authors affirm that their lance maximizes the droplet generation without causing spitting. In this work, the performance of a lance with four peripheral nozzles and one vertical centered nozzle is numerically modeled by means of Computational Fluid Dynamics software. Transient two dimensional computer simulations were carried out considering two phases, namely molten steel and gaseous oxygen. Numerical results confirm that bath agitation and droplet generation are enhanced as a result of the vertical centered nozzle, however a proper performance of this lance, related to a conventional one, strongly depends on the Mach number of the oxygen jets and the lance height.

Jan 1, 2008

By P. Myllykoski, J. Nylander

"A commercial program package called Crownoff for the simulation of temper rolling in four high mills has been verified against measured data. The agreement between measured and calculated transversal strain distributions of the strip was found to be good. Effects of the strip crown and work roll bending force on the strain distribution were simulated. The results showed that when a single ground camber of work rolls is used for all strip widths; the strip crown should be parabolic, excluding the edge drop. An increase or decrease of the strip crown by 30 % during a coil can be compensated by a 2 to 5 t change in the work roll bending force. The ability to control the strip crown by work roll bending was insensitive to strip width. IntroductionCold rolled steel strips are usually temper rolled after recrystallization annealing, which follows cold rolling. The purpose of temper rolling is to suppress the yield point, finish the strip surface and correct possible flatness errors. The presence of a yield point might otherwise cause problems during subsequent forming processes. The in homogenous yielding in non-temper rolled steels leads to the formation of Lüders bands in the strip surface.The rolling force is influenced by the rolling speed and changes in frictional conditions in the roll bite. Therefore it is very important to plan carefully the mill settings and control algorithms during rolling. The purpose of mill control algorithms is to ensure constant reduction and the best possible strip flatness during the entire coil.Correctly predicting the rolling force is important for determining the mill presettings. Torque, forward slip and power requirements are not usually critical, if the reductions are small. However, the large elastic deformations occurring in the roll bite make the physical description of the process difficult. Physical rolling models developed for cold rolling contain assumptions that lose their validity as the reductions decrease to the level of one per cent."

Jan 1, 1994

By Susumu Okabe, Etsuji Kimura

"The Mitsubishi Continuous Copper Smelting and Converting Process is the typical applications of injection metallurgy to nonferrous metallurgical operation, where the top blowing multiple lance system is employed for the continuous feeding of the raw materials and reaction gases into the molten bath. This results in an effective dispersion of the reactants into a strongly agitated bath. These are considered as the major advantage of the process with respect to the high production efficiency. On the other hand, however, the strong agitation may cause a considerable amount of refractory wear, and the melt splash generated by the lancing may also have negative effects on the productivity, i.e. the increase in the refractory wear, the metal loss, the heat loss, and the accretion growth, etc. Therefore, the optimization of the blowing condition as wen as furnace design is very important to achieve a stable and efficient operation, and fundamental understanding of the injection, agitation, and splashing is badly needed.In this paper, fundamental aspects of the Mitsubishi Process regarding injection, especially splashing phenomena, are discussed. The splashing on a vertical plane caused by the top blowing gas injection onto liquid surface was investigated through physical model study. As a result of the study, the splashing rate on the furnace wan was wen correlated with the physical properties of the bath materials, gas velocity, cavity shape, lance/wall distance and ceiling position. Obtained equations were compiled in a computer program and have been successfully applied to the evaluation of the furnace design. IntroductionInjection metallurgy is an application of gas/solid-in-liquid dispersing operation to the metallurgical processing, and has been widely adopted in various fields in order to improve their efficiency or productivity. The dispersed small particles of gas or solid materials in the liquid phase result in increased interface area, and injected momentum causes an agitation and enhanced heat and materiel transfer. Typical examples of injection metallurgy are LD converter for steel making, PS converter, Noranda process, Isasme1t for copper making, and Mitsubishi Material's continuous copper smelting and converting process, and so on."

Jan 1, 1996

By Timothy W. Ellis

This paper presents the basic theory of operation, physical chemistry and phase equilibria which allow the development of liquid-liquid extraction circuits based on metallic solvents. The incorporation of reduction and reduction/diffusion processes into the process 'scheme is discussed and a detailed description of ,several liquid-liquid extraction schemes are developed. A synopsis of experimental results obtained using this: method to separate rare earth and other metal based materials will be given.

Jan 1, 1996

By Thomas Niehoff, Yin Qing, Wei Zhongling, Liu Yongguo, Zhang Deliang, Tang Le

The gold ore of Shandong Gold Mining (Xinhui) was a refractory ore, which contained multi metallic sulfides (ZnS and PbS etc.) and carbonaceous. The gold ore concentrate came into leaching process and thickener and zinc replacement to recover gold. In order to improve gold recovery, the GOLDOX™ hydrometallurgy process was studied in Shandong Gold (Xinhui) by bench scale and 6 month plant scale test supported by Linde Gas. It was shown that the process promoted the leaching kinetics and improved gold recovery. The residue grade reduced 0.22 g/t in average after oxygen was applied. This indicates an operating profit increase 850,000 yuan/a in the plant. It was setting a good example for similar gold mine plant and would promote the oxygen application in Chinese gold mining industry.

Jan 1, 2015

By Tao Zhang, Wen-tao YU, Hai-bin ZUO, Jian-Liang Zhang

Sintering-pot tests and metallurgical performances of sinter with 4 kind of different Al2O3 contents are experimented in this paper. Results show: when the Al2O3 contents increase from 2.0% to 3.5%, acicular calcium ferrites in mine phase will be gradually replaced by plate-like iron calcium. The increase of Al2O3 contents will lead to the addition of liquid viscosity and the reduction of permeability of sinter bed. Sintering time will be prolonged. The rate of yield is stable basically but production is low; besides, the increase of liquid viscosity will decrease of drum strength. The change of permeability of the material layer will make RDI +3.15 decrease first and then increase when Al2O3 contents changed from 2.0% to 3.5%. RI of sinter shows a contrary trend because many open voids are formed by deterioration of liquidity first and then pores closed.

Jan 1, 2015

By Cheryl S. Lim

New technologies such as direct reduction and smelting reduction processes are increasingly being used in iron-making and steel-making in addition to conventional blast furnace technology. Critical parameters for control of these processes include the degree of metallization, degree of pre-reduction, and carbon and silica levels. On-line monitoring of these parameters is difficult because measurements often need to be made on hot ores (at or higher than -1000'C) in circumstances where representative sample streams are not readily accessible. A nuclear analyser has been developed which provides continuous, non¬intrusive, real-time measurements of iron, oxygen, carbon and silicon levels in hot ores undergoing reduction. The analyser has been tested in a plant using a direct smelting process on pre-reduced feed to the smelting vessel-, accuracies of 1% relative, 0.5 w'.96 (25% relative) and 1.0 wt.% (9% relative) were obtained for the degree of pre-reduction, carbon and silica respectively. The underlying method, capabilities and potential applications of the analyser will be discussed.

Jan 1, 2001

By Shuqiang Guo, Dingsheng Tan, Weizhong Ding, Zunyu Hu

"The mixture of hydrochloric acid and magnesium chloride is a good lixiviant for leaching of laterite. The solution can enhance the leaching ability because of the proton activity deviated positively from ideal. Otherwise, the existence of magnesium chloride in the lixiviant affects the dissolution behavior of magnesia, which may be an advantage of the process with less hydrochloric acid consumption. An investigation of magnesia particle dissolved in strong hydrochloric acid solution has been conducted. Influences of concentration of the magnesium chloride and hydrochloric acid and temperature on magnesia dissolution were studied. The dissolution mechanism was also discussed in this paper.IntroductionThere has recently been much interest in the use of hydrochloric acid leaching processes for recovering metal from ores or secondary resources [l-41_ Compared with sulfuric acid, the use of hydrochloric acid as lixiviant offers significant advantages including faster leaching kinetics even at atmospheric conditions, higher leaching rate and greater solubility for most metal chlorides [5-61 .With the gradual decline of the nickel sulfide supply, the extraction of nickel from laterites has become increasingly attractive [7-s1. Nickel may be co=ercially recovered from laterites both by pyrometallurgical and hydrometallurgical processes. The drawbacks of pyrometallurgical processes include the requirement of high grade ores, substantial energy input and loss of cobalt bound within ores. The extraction of Ni from lower grade nickel laterites ores is suited by hydrometallurgical routes, which play an increasingly important role with depletion of higher grade deposits."

Jan 1, 2014

By Baozhong Zhao

Experimental results have shown that fluxing with soda ash (Na:zC03) can remove As and Sb from molten copper at the rate of As>Sb, but is relatively ineffective in removing Hi. The rate of impurity removal is controlled by impurity mass transfer in the metal phase. In this paper, a mathematical model was developed to describe the impurity removal phenomena. The model incorporates the effects of molten bath mixing intensity, soda ash feeding rate, oxygen content in the molten copper and soda ash fluxing by surface addition and injection. The model predictions are in good agreement with experimental results and may be used in designing large scale tests.

Jan 1, 1996

By Frederico Muylaert Margem, Giulio Rodrigues Altoé, Glenio Daniel, Pedro Amoy Netto, Sergio Neves Monteiro, Maria Carolina Andrade Teles

The environmental concern is creating pressure for the substitution of high energy consumption materials for natural and sustainable ones. Compared to synthetic fibers, natural fibers have shown advantages in technical aspects such as flexibility and toughness. So there is a growing worldwide interest in the use of these fibers. Fique fiber extracted from fique plant, presents some significant characteristic, but until now only few studies on fique fiber were performed. This work aims to make the analysis of the tensile strength of polyester composites reinforced with fique fibers. The fibers were incorporated into the polyester matrix with volume fraction from 0 to 30%. After fracture the specimens were analyzed by a SEM (scanning electron microscope).

Jan 1, 2015