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By A. S. Usrnani

Due to both turbulence and the highly variable geometry of castings, a realistic numerical simulation of the metal flow is prohibitvely expensive with current technology. However, when the chief purpose is to achieve realistic thermal fields a precise How simulation is not necessarily required. In this paper we assume a laminar flow regime and obtain the flow field by solving the incompressible Navier-Stokes Equations using a velocity-pressure segregated semi-implicit finite element method. The free metal surface is predicted by advecting a pseudo-concentration function via the computed How field. This involves an explicit finite element solution of a pure advection equation. The thermal field is calculated by solving the convective-diffusive energy equation by an explicit finite element method using the computed flow field and the location of the free surface. All the advection terms are discretized using a Taylor-Galerkin method. The interface between the metal and mould is modelled using special interface elements. The model is demonstrated by solving practical example problems. The results show that a sharp thermal front is maintained during the course of filling without excessive diffusion. The heat diffusion in the mould can be controlled by varying the metal mould heat transfer coefficient.

Jan 1, 1994

By Ho-Sang Sohn

The kinetic study on desulfurization of copper matte by gas bubbling was designed under the presumptions of lower FeO activity and of no slag formation, Copper matte with 59% Cu and 22.6% S in weight was oxidized at 1523K by bubbling of Ar + O2 gas through a submerged nozzle. The effects of oxygen partial pressure and flow rate of gas on the oxidation rate of matte were discussed. The desulfurization rate and the evolution rate of SO2 gas of copper matte were significantly influenced by the oxygen partial pressure, but the dependence on gas flow rate was rather complicated. The desulfurization rate and evolution rate of SO2 gas of copper matte were described by the mass transfer rate through the gas film around the rising gas bubbles. Thermodynamic correlation equations between the partial pressure of gaseous species and matte composition were incorporated to the kinetic calculation, The present model shows that the reaction path starts to transiently cross over an isobar line of PSO2 to asymptotically approach to the particular isobar line drawn in a matte composition plane of %S and %O.

Jan 1, 2003

By A. Deneys

An experimental technique has been devised for studying the reaction kinetics of the reaction: ZnO + 2Fe0 = Zn(g) + Fe203, by which zinc evolution can occur from a molten slag bath in the absence of a carbonaceous reductant. When studying the reaction kinetics by heating from room temperature, solid state reactions and poorly defined melting points may obscure the starting point of the reaction. In order to eliminate this problem, an experimental technique was devised whereby two molten slags could be melted independently, and then mixed, to provide a well defined starting point from which to begin taking measurements. Two crucibles were mounted in a vertical reaction cylinder. The upper, mild steel, crucible had a bottom pouring plug which was sealed by a steel stopper rod. A fayalite mixture was contained in this crucible. The lower crucible contained an A12O3-CaO-SiO2-ZnO solution. Once the two slags had been melted, the steel stopper rod was removed from the upper crucible. The upper, reduced slag (fayalite in equilibrium with the upper steel crucible), drained into the lower crucible where the two slags were mixed by submerged argon stirring. Dip samples were taken to measure the zinc content of the final mixture as a function of time. The experimental procedure will be described, as well as results of experiments which were conducted on synthetic slags. The system investigated was similar to the lead blast furnace slag which is produced by the primary lead smelters of Missouri, USA.

Jan 1, 1997

By Ahmet Geveci

[Generally accepted formula related to sulfur slag-metal distribution ratio is given by the following equation: [ ] According to the above equation it can be deduced that sulfur distribution between slag and metal is governed mainly by metal composition (?s term), slag composition (slag basicity and in turn sulfide capacity), oxygen potential of the system (ao¬¬ term) and temperature(related to equilibrium constant, K). In this study, the results of ladle furnace operations conducted in Erdemir-Iron and Steel Works Co. (Turkey) in relation to sulfur removal, have been given. Typical ladle furnace slag analyses of 4937K quality steel have been presented. Activity coefficient of FetO,?FetO, have been calculated with the relation obtained fromthe literature. Activity calculations have been performed with the program written in Mathcad. The changes in activity of aFetO in the slag phase,, have also been studied in relation to the sulfur removal: The relation between % Decrease aFetO and %DeS (measured)have been investigated for 4937K runs and someother types of steel produced in the Erdemir Plant. Related to ladle operations %desulfurization defined as [(%Sinitial-%Sfinal)/S%initial]*100 values have been presented for different steel qualities.]

Jan 1, 2006

By Moto Goto

Onahama Smelter of Onahama Smelting & Refining Co., Ltd. has two green- charge reverberatory furnaces; the old furnace was constructed in 1965 and the new one in 1973. This paper discusses the use of oxygen-oil burners in a green-charge reverberatory furnace and also compares the copper loss in slag between the two furnaces at Onahama Smelter. During the past ten years of operation, no shutdowns of the old furnace were necessary and the smelting capacity was increased by 25% by the use of two oxygen-oil burners. These burners are suitable for a green-charge reverberatory furnace to in- crease the smelting capacity without causing an increase of the exhaust gas volume and refractory erosion. After two years of operation of the old furnace, a bottom build-up in the charging zone of approximately 50 centimeters was experienced, and this build-up has stayed at this level since then. In 1973, a new additional reverberatory furnace was put into operation. Copper content in slag of the new furnace was lower by approximately 0.15% than that of the old one during the first several months after the start-up. Investigations were then made on the effect of the bottom conditions in the charging zone on the copper content in slag.

Jan 1, 1976

By Jilai Xue, Jun Zhu, Baisong Li

"TiB2-C/C Function Gradient Materials (FGM) is used in cathode materials to improve aluminum wettability and melt penetration in aluminum electrolysis. In this investigation, FGM was tested for use as part of the cathode materials, where a 10 mm thick TiB2-rich layer was on the top as an Al-wettable surface, the TiB2-C layers in the middle as a gradient layer and the carbon on the bottom as a base. Electrical resistances ofFGM were determined in the temperature range of25- 9600C in argon atmosphere. The results show that the present of TiB2-C gradient layer can reduce the open porosity and the electrical resistance of the cathodes materials at elevated temperatures. The cathode samples after aluminum electrolysis usually demonstrates an increase in electrical resistance, but the application of FGM layer can compensate such an increase for certain extend due to less variation in porosity and lower the level of melts penetration.IntroductionCarbon is still used for aluminum reduction cathodes dominantly, but it has a poor wetting properties by liquid aluminum and the anode-cathode distance has to be kept about 4-5cm with an additional 1.3-2.0 V voltage drop [l]. TiB2 has better wettability by liquid aluminum with higher electrical conductivity and stronger chemical resistance to the electrolyte attack. And the wettability ofTiB2-C composites cathode on liquid aluminum can be also improved, while liquid aluminum can completely wet the cathode surface ifTiB2 content exceeds 27% [2-4]. However, during the process of TiB2-C composites cathodes preparation and aluminum electrolysis, the deformation by temperature variation or sodium penetration are great disparity between TiB2 and carbon due to their physical properties difference. This will accelerate the cathodes cracking and deterioration."

Jan 1, 2013

By Theodore Ineich

The “BIOMOre” project aims to prove the technical feasibility of indirect in situ bioleaching of sulfide minerals contained in a deep underground deposit, by bringing together the disciplines required to make a success. The underground location in Poland was provided by project partner KGHM inside an operating copper mine. Key components of this project were the design and construction of a pilot plant, and its operation in an underground environment. This project also included a ∼250 t (100 m3) fragmented rock reactor hydraulically connected to the pilot plant. The pilot plant consisted of several tanks and pumps, a fluidised bed ferric iron generating bioreactor containing immobilised acidophilic iron oxidation biomass, and all the required instrumentation and utilities. Before the bioleaching phase could start, the rock reactor had to be flushed continuously firstly with water to remove chloride salts that are corrosive and also harmful for the bacteria used in the bioreactor, and secondly, with sulfuric acid solution to react with the carbonates present in the ore matrix. This paper summarizes the design, construction, commissioning, and operation of the pilot plant.

By Deepak Gupta, R. Kageyamat, J. W. Evans

"In electromagnetic casting, a liquid metal pool is partly supported by electromagnetic forces resulting from the interaction between induced currents and an alternating magnetic field. Stability of the metal surface is of paramount importance if the cast ingot is to be free from surface defects. Prior work by Garnier and Moreau had suggested that the magnetic field has no influence on the surface stability, but a more complete analysis at Berkeley suggested that surface perturbations are destabilized by the magnetic field once a critical magnetic field is exceeded. More recently we have employed a modified version of the software SOLA to compute the behaviour of a melt surface in the presence of an alternating field. The computed results support the theoretical analysis in predicting an unstable surface. Experimental work is now in progress to examine the stability of a mercury pool in the presence of an alternating field. Introduction and Previous InvestigationsElectromagnetic casting (EMC) is a technique widely employed in the aluminum industry to produce ingot for subsequent rolling. It is a ""continuous"" casting technique (illustrated in Fig. 1) producing ingots several meters high (and perhaps 1m by 2m in horizontal dimensions) at a casting speed of one or two mm. per second. The technology has gained acceptance because the metal is solidified without contact with a mold. Consequently the surface finish of the ingot is usually smooth and the ingot can be fed directly to rolling without machining, the surface (""scalping""). Scalping is necessary with alternative technologies (e.g., DC casting) where a mold is used. Consequently any disturbances that result in surface imperfections of EMC ingot are a serious matter. One type of imperfection is waviness on the surface of the ingot; a line drawn along the crest of a wave would run horizontally around the ingot. This imperfection may be caused by waves on the surface of the metal pool. As the waves reach the solidification line at the periphery of the metal they cause alternate outward and inward bowing of the meniscus at that point with attendant small (but significant) changes in ingot width. Elimination of building vibrations and similar disturbances minimize the occurrence of these surface waves but it is interesting to speculate whether there are disturbances of the metal pool that arise from the electromagnetic forces supporting the liquid metal. These forces are generated by the interaction of currents induced in the melt and the magnetic field produced by the current imposed on the inductor surrounding the melt. The present investigation has been concerned with whether the alternating magnetic field destabilizes the melt surface."

Jan 1, 1994

By Robert D. Pehlke

"Current continuous casting processes are going through a rapid evolution of advances and new developments. At the same time, intense efforts are being directed to the development of radical new technologies such as continuous casting of thin slabs and strip steel.Traditionally, the casting processes for steel have been anticipated by the development and implementation of processes in the non-ferrous industry. This trend is reviewed and what it may portend for steel is described.IntroductionThe continuous casting of steel has been a widely adopted process in the production of steel. The concepts for this processing go back into the early and mid 1800's; however, commerical development was delayed for a variety of reasons until the mid twentieth century.Beginning in the early 1960's, adoption of continuous casting was initiated and continues at this point in time to be accelerated. In Japan, more than 90% of the steel produced is continuously cast (1). More than 50% of the steel produced in the United States is continuously cast and this fraction continues to rise (2). Numerous examples can be cited of installations costing well over $200,000,000 which have provided a payoff in less than a year and a half. As this process has continued to be applied and its technology to increase, computer control systems have been installed. In particular, in the larger plants producing slabs, sophisticated computer systems involving the integration and networking of mini-computers, micro-computers, and mainframe including back-up systems at all levels are being utilized. Pehlke (3), and Harabuchi and Pehlke (4) have described the structure of these systems."

Jan 1, 1988

At its Copper Cliff Smelter, Inco Limited processes a bulk copper-nickel concentrate in two Inco oxygen flash furnaces. The furnace matte is converted to low iron matte for further processing, and the molten converter slag is recycled to the flash furnaces. The flash furnace slag is discarded. Natural gas or coke supplies a minor proportion of the process heat requirements, thus limiting the flash furnace matte grade to the target 45% CuNiCo. Coke addition to the furnace offers a potential means of establishing a reducing barrier on the surface of the molten bath. Such a practice would be conducive to producing sulfur deficient (partially metallized) matte. At the same iron content, the iron activity of sulfur deficient matte is higher than that of regular matte. A supernatant coke barrier could, therefore, be expected to lead to higher nickel and cobalt recoveries, reduction or even elimination of magnetite furnace bottom build-up and increased sulfur elimination as SO2 in the flash furnace. Preliminary experiments were conducted in a mini plant flash furnace to investigate the effect on process metallurgy of the suggested modified scheme. This paper presents the experimental results and discusses key aspects of the possible operation of the Inco flash furnace with a coke barrier separating the freeboard from the molten bath.

Jan 1, 2003

By P. A. Rusin

Many manganiferous silver deposits remain undeveloped because standard chemical extraction methods yield poor recoveries or are ' environmentally unacceptable. Biotreatment of such ore deposits in our laboratory resulted in manganese and silver recoveries of greater than 90%. Ore and sediment samples were collected from mining sites in Colorado and Arizona. Portions of samples were incubated in a semi-solid mineral salts medium amended with 20 mM glucose mid manganese dioxide (Mn medium). The cultures were incubated at 3(fC until manganese reduction was detected by a .color change fr:om .black to clear. Bacteria from these cultures were purified on Tryptic Soy Agar and individual isolates were retested for Mn reduction by an agar overlay method. Bacteria were identified according to Bergefs Manual ?of Systematic . Bacteriology. Most of the Mn-reducing bacteria are Bacillus species. Bacterial manganese reduction kinetic experiments were performed in 52 ml mineral salts broth supplemented with manganiferous silver ore instead of manganese dioiide. These cultures were incubated with agitation for 16 d. Aliquots were removed periodically and analyzed for solubilized manganese by atoniic absorption (AA). Cyanide (1,0 M) Vias added to the remaining ore-medium mixture for a 24 h bottle roll. The supernatant was analyzed for soluble silver by AA. Similar experiments were conducted on a larger scale using 15% pulp density. After bfotreatment of the ore, standard bottle rolls were performed. The pregnant solutions and the residues were analyzed for manganese and silver?using AA or fire assay as appropriate. In sterile. controls-which received no biotreatment, manganese and silver recoveries were 0.3% and 10% respectively; During biotreatment, total manganese solubilizatiori was as high as 99.8%. The reduced manganese could . be stripped from ?the growth medium using hydrometallurgical techniques. Silver recovery vaned from 70% to 92.5%. Microbial treatment of refractory mangairlferous ores can result in high recoveries of manganese and silver. Retention time varies depending upon the relative concentrations of manganese, silver, and other metals in the ore with only two days required in some cases, The biotreatment of ore is environmentally' acceptable while the use. of chemicals such as sulfur dioxide is less so.

Jan 1, 1991

By K. Adham

For use in many existing and emerging applications, the purification of natural graphite is required to achieve +99.9% carbon content with minimum metallic impurities. Currently, the hydrofluoric acid process is used, which carries certain environmental and workplace health and safety impacts. While thermal purification of graphite at temperatures over 2500 °C is a known alternative, such high-temperature furnaces are expensive to build and operate. Using chlorine at lower temperatures to purify graphite is also known and patented, but is currently limited to treating solid synthetic graphite shapes in small-scale batch furnaces. Chlorine treatment of natural flake graphite resources can be used commercially, if certain drawbacks are addressed through process improvements that can be helped with the use of fluidized bed reactor technology.

By R. Padilla

A thermogravimetric study has been conducted to follow the decomposition and volatilization of arsenic from enargite concentrate in nitrogen and slightly oxidizing atmospheres. Temperature has a large effect on the rate of volatilization of arsenic. Fractional volatilization of arsenic as high as 98% were obtained in less than 60 min at 650°C in nitrogen atmosphere, while in slightly oxidizing atmosphere the same volatilization could be achieved in 30 min. It was found that arsenic volatilizes as sulfide in nitrogen atmosphere and as 4xture of sulfide and oxide in atmospheres containing 1% oxygen. By using the pore blocking and the first order kinetic models, apparent activation energies of 213 and 200 kJ/mol for the temperature range of 780 - 900 K and 205 and 184 kJ/mol for the temperature range of 900 - 985 K were determined for enargite and copper concentrate, respectively.

Jan 1, 1997

By Bin Zhu, Mingmei Zhu, Hong Zhou, Xiaofei Dou, Bin Xie, Yu Wang, Tiancheng Lin

In this study, the formation of 2CaO·SiO2 and 3CaO·P2O5 solid solution (nC2S-C3P) in hot metal dephosphorization process is discussed. The variations of CaO and SiO2 mass, both in nC2S-C3P solid solution phase and liquid slag phase with increasing P2O5 mass in CaO-SiO2-FetO-P2O5 slags were calculated using Factsage software. CaO-SiO2-FeOt-P2O5 slag containing up to 18 % P2O5 was melted at 1823 K then cooled to 1673 K. The contents of CaO and SiO2 both in the solid solution phase and liquid slag phase of quenched samples were observed and analyzed by SEM/EDS. Both the calculated and experimental results show that the contents of CaO and SiO2 in the solid solution phase decreased, just opposite in the liquid slag phase, with increasing P2O5 content in the slags. Formation mechanism of nC2S-C3P solid solution in the slags was derived based on the ionic structure theory of molten slag. The SiO4 4- in the nC2S-C3P solid solution can be replaced by PO4 3- in the liquid phase resulting in the increasing of free Ca2+ and SiO4 4- in liquid phase.

Jan 1, 2015

By Y. Z. Zhang

Electrochemical oxidation of arsenopyrite in ferric sulphate media in the absence and presence of bacteria T jerrooxidans has been investigated for the purpose of understanding the dissolution chemistry of arsenopyrite and the bacteria attack mechanism. Mixed potential, polarization resistance measurements, polarization curve, cyclic voltammetry experiments were conducted in a ferric sulphate medium of 10g/L FeH, temp.25-35°C, pH 1.5-2.5 in the absence and presence of bacteria Tjerrooxidans, respectively. For the anodic process, a two-step reaction sequence is suggested by the electrochemical measurements. The initial step at a low potential is described by:

Jan 1, 1996

By André Laplante

The mineralogy of the Joe Mann mine differs from that of other deposits of the Chibougamau area that are exploited by Les Mines Camchib Inc.. It is characterized by very fine first generation gold and very coarse second generation electrurn. Successful milling required adjustments of the processing flowsheet, which includes gravity, flotation, and cyanidation. A study of coarse gold liberation in the gravity/grinding circuit is described. Modifications to the flotation circuit and the reconditioning of a small capacity cyanidation circuit are presented. As a result of the circuit modifications, gold recovery increased from 65 to 81% in flotation and cyanidation. Overall gold recovery increased from 77% to 88-89%. These improvements are mostly attibutable to the recovery of -10 urn gold, whose presence in the Joe Mann ore and original circuit tails had been identified by process mineralogy.

Jan 1, 1989

By Hong Yong Sohn

A novel flash ironmaking technology is under development at the University of Utah under the support of U.S. Department of Energy (DOE) and American Iron and Steel Institute (AISI). The history of the development from the conception of the idea to the current status will be discussed. The flash ironmaking process produces iron directly from fine iron ore concentrates without requiring cokemaking and pelletization/sintering, which will enable the technology to significantly reduce energy consumption and carbon dioxide emissions compared with blast furnace ironmaking. Unlike other gas-based ironmaking processes, this technology will not suffer from the problems of solid sticking and fusion. Current work is focused on the method of supplying the energy required to maintain the necessary temperature, as an intermediate step to determine the scalability for larger, industrial-scale pilot trials.

Jan 1, 2014

By José R. de Tenorio

The aim of the present work was to investigate the reduction process of MnO~FeO-Si02 slags by carbon-saturated liquid iron. The effect of the initial Mn content in the bath was explored. The initial Mn content was in the range of 0 up to 40 wt. %. The MnO content in the slag was kept constant at 40 wt. %. Tests were performed in laboratory apparatus. Samples of slags and bath were taken. In the first 5 minutes, it was observed a very strong reduction of FeO. This first step promoted a MnO-Si02 enrichment of the slag and a formation of CO bubbles, which increases the slag level. The increase ofMn content decreases the MnO reduction rate.

Jan 1, 1996

By Charles A. Sorrell

Two red muds, two fly ashes, and several aluminosilicate minerals were subjected to direct treatment with concentrated H2SO4 at temperatures of 175°C and below. X-ray analysis showed that virtually all the sulfate reaction products remained in the solid residue because of their low solubilities in x SO Substantial portions of the Al2O3 Fe2O3TiO2, Na2O, and K2O components of the materials reacted to form water soluble sulfates, which were then removed by H2O leaching at 55°C. The solid residue after water leaching consisted largely of amorphous silica and, in lime bearing compounds, CaSO4, The reaction and leaching processes were effective in removing all or nearly all the Al2O3. Fe2O3, TiO2, Na2O, and in lime components in the fly ashes, red muds, china clay, bentonites, the nephelioe fraction of nepheline syenite, and a plaster insulating brick composed of anorthite and mullite. Reaction with potassium feldspar and petalite took place, with formation of alkali aluminum sulfates, but the reaction rates and yields were extremely low. Potassium feldspar can be heated with Na2O and x O in air at 700°C for 24 hours, or with CaO at 1000°C for 24 hours, after which the reaction product kaliophilite, nepheline, and leucite-like phases, prove to be very susceptible to H2SO4, reaction and H2O leaching, providing yields near 100% of the Al2O2 content. An alternative method of H SO treatment consists of heating the sample in a silica tube and passing H2SO4 vapor over it. Preliminary results indicate that this method can be effective in enhancing the kinetics of reaction with the Al O component of potassium feldspar and offer the possibility that formation of Al2 (SO ) Fe2(SO4)3 and TiOSO4 can be accomplished selectively by taking advantage of the fact that the upper stability limits of the respective sulfates in the presence of H2SO4 vapor will be different.

Jan 1, 1982

By C. S. Griffith

Lithium Australia NL (ASX:LIT) and ANSTO Minerals have been working together since 2015 on the development of halide accelerated leaching for the extraction of lithium from lithium-bearing micas, spodumene and clays. This technology has been termed SiLeach® process. The driving force behind development of the SiLeach® process, initially, was to develop a hydrometallurgical process to extract lithium from micas and spodumene without the need for the energy intensive, high temperature processing conventionally applied to lithium extraction. This driving force remains today and continues to hold promise in realising the value of previously under-utilised lithium resources. A comprehensive understanding of the technology and its applicability to the processing of micas and spodumene currently exists, and the flowsheet has been rigorously piloted. Production of battery grade lithium carbonate has been demonstrate