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By Gabriel Zarate

Mantoverde is a heap leach-SX-EW plant that was commissioned in December 1995 at a production rate of 42,130 tonnes of copper per year and 5.4 million tonnes of ore per year. Copper production was steadily increased reaching a maximum of 62,239 tonnes in 2012 for an ore throughput of 10,5 million tonnes. In order to get these production and throughput rates, a number of changes have been made in the metallurgical parameters of the plant operation since the start up, among them particle size, heap height, acid addition distribution in curing and leaching solution, leach cycles and pad type. Most of the modifications have been implemented after carrying out extensive column test work programs. The modifications implemented and the results obtained, as well as the test work programs carried out, are discussed in this paper.

By J. Alberto Vázquez M.

A sensor employing yttria-stabilized zirconia (YSZ) was used to determine the oxygen activity of molten copper at laboratory scale at temperatures of 1200° and 1300 dc. The reference electrode was a Ni-NiO mixture. The amount of the deoxidizing agent (CU3P) ranged from I to 3% of the mass of copper. Thermodynamic analysis of the Cu-O-P liquid system was carried out to predict the required deoxidizing agent and the final composition of the molten copper. Both results, calculated and experimental, show that the oxygen removal is more efficient at lower temperatures. The kinetics of the deoxidizing reaction is very fast in the first minutes of the treatment. A metalography analysis of rapid cooled samples show the oxygen and phosphorus distribution

Jan 1, 2003

By Ralph P. Hackl

Bacterial leaching of the Doe Run Company?s cobalt/nickel-containing copper concentrate at low pH (pH 1.0-1.2) and high redox potential (>750 mV vs. SHE) enabled the cobalt and nickel to be preferentially dissolved over copper and iron due to the rapid passivation of the chalcopyrite component. Selective leaching of the cobalt and nickel was achieved with a mesophilic culture comprised mainly of Leptospirillum-like bacteria and Acidithiobacillus thiooxidans. This finding led to the conception of a novel hydrometallurgical process for passivating chalcopyrite and recovering the cobalt and nickel. The bacterial leaching process was tested extensively at the bench and pilot plant scales during 1997-1998. A pilot plant containing four leaching stages processed 30-40 kg/day of chalcopyrite concentrate continuously for 87 days. The cobalt extraction ranged from 75% to 86% during 6- and 8-day retention times respectively, whereas the copper extraction was limited to about 9%

Jan 1, 2003

By Karin Soldenhoff

Recovery of uranium in conventional ion exchange circuits, using strong base or weak base resins containing quaternary or tertiary amine functional groups, is based on an anion exchange mechanism. In saline liquors, chloride competes with uranium for the active resin sites and reduces resin loading. This results in significant negative impacts on the IX process in terms of plant throughput and operating costs. In this paper we present the results of a study on the recovery of uranium from an acidic in situ leach liquor containing approximately 9 g/L chloride. A range of resins was tested, and a high capacity strong base resin was identified with significantly enhanced loading compared to conventional resins. Other process-relevant criteria such as loading kinetics and elution efficacy are also discussed. The process developed was successfully tested during a recent ion exchange pilot plant operated in conjunction with a field-leach trial.

By V. L. Stolyarova

The high-temperature Knudsen effusion method was used to study partial pressures of vapour species, activities of components and the Gibbs free energies in the DyF3-Dy2O3 system at the temperature (1357±5) K. Partial pressures of vapour species were obtained by the ion current comparison method, with the DyF3 partial vapour pressure over pure DyF3 as a standard. The equilibrium constant of the gaseous reaction DyF3 + DyOF = Dy2OF4 is evaluated. Thermodynamic data obtained are in a agreement with the available phase diagram of the DyF3-Dy2O3 system. Results of the present study illustrate the negative deviations from the ideal behaviour in the system.

Jan 1, 1997

By Toshihiro Kuzuya

A hydro metallurgical process has been developed for the recovery of metal values such as Co, Ni and rare earths from the electrode materials of spent nickel metal-hydride(Ni-MH) secondary battery. MmNis_xCo. (Mm : Misch metal) intermetallic compound could be separated from the electrode materials mixture by sedimentation. A typical chemical composition of MmN5-xCox was approximately, in mass%, 56.0%Ni, 13.4%Ce, 10.6%La and 7.9%Co. The time dependency of leaching intermetallic compound with sulfuric acid solution was examined with processing factors such as sulfuric acid concentration, temperature and agitation intensity, The leaching of rare earth metals proceeded very rapidly, reaching completion in less than 1.8ks. On the other hand, the slow leaching of nickel was observed. The percent of nickel leached at 328K could only reach about 70%.

Jan 1, 2003

By C. A. Silva

The kinetics of chlorination of titanium-bearing raw materials has been investigated. For comparison purposes pellets of controlled macro-porosity, made of analytical grade TiO2 and anatase concentrate (Brazil) , have been exposed to different combinations of gas composition - CO, CO2, C12 -, gas flowrate and temperature. A thermogravimetric technique and an adapted grain model have been used in order to assess the influence of the several experimental parameters upon the chlorination behavior.

Jan 1, 1997

By Wei Yu, Tiejun Chun, Jian Pan, Deqing Zhu

In this paper, the technology of producing fluxed pellets by using hydrated lime as binder instead of bentonite was carried out. Green balls with 0.8% bentonite and others with 2% hydrated lime were obtained under the same conditions of 1.5% coke, 1.45 basicity and balling at 8.5% moisture for 13 min in disc pelletizer. The properties of two types green balls were as follows: drop numbers of 4.8 to 5.0 times/0.5m, compressive strength of 19.7 to 24.2 N/pellet and thermal shock temperature of 280 to 385?, respectively. Comparing with bentonite as binder, the compressive strength of fired pellets with hydrated lime is elevated by 13.8% and climbs up to 3113 N/pellet under the following conditions: preheating at 1050? for 10 min and firing at 1300? for 15 min. The hydrated lime also improves the metallurgical performance of fired pellets. The reduction index was enhanced from 68.6% to 70.6%, RDI+3.15 increased from 90.1% to 98.8% and reduction swelling index dropped from 22.4% to 7.4%, respectively. Therefore, hydrated lime can not only replace bentonite as binder to enhance the firing behaviors of green balls, but also effectively improve the metallurgical performance of fluxed pellets which can be used as high quality feed for blast furnace.

Jan 1, 2011

By Katie Schumacher, Greg Roset, Dayle Flynn

The Columbus Processing Complex of the Stillwater Mining Company began operations at Columbus, Montana in 1990 based on electric furnace smelting treating a precious metals concentrate from the nearby Stillwater mine and mill. Since that time, the smelter plant has been expanded in stages in order to treat recycled materials in addition to the concentrate. This paper describes a number of changes made at the plant to effectively handle recycled materials.

Jan 1, 2014

By Alfonso Nájera

Turbulent flow of liquid steel and its control is studied using different geometries of turbulence inhibitors. Four designs of turbulence inhibitors were characterized through experiments of tracer injection I a water model and mathematical simulations using the Reynolds Stress Model (RSM) of turbulence. Geometries included octagonal-regular, octagonal-irregular, pentagonal and squared. A layer of oil was used to model the behaviour of tundish flux during steel flow. Fluid flows in a tundish using these geometries were compared with that in a bare tundish. Experimental and simulation results indicate that the flow in the bare tundish and a tundish using turbulence inhibitors open large areas of oil due to strong shear stresses at the water-oil interface but the squared inhibitor. These phenomena are explained by the high gradient of the dissipation rate of the turbulent kinetic energy using the squared inhibitor. Using this device the kinetic energy reports a high gradient from the tundish floor to the free bath surface as compared with other geometries.

Jan 1, 2006

By Yoshisada Michiura, Junko Umeda, Katsuyoshi Kondoh

Rice husks or straws, one of the main agricultural wastes in South-east Asia, have a large possibility to be employed as usefully renewable resources to produce energy and high-purity silica (SiO2), because they consist of about 70% organics such as cellulose or hemi-cellulose, and 20% amorphous SiO2. The former is utilized as bio-mass energy; for example, thermal or electric energy, and bio-mass ethanol. High-purity silica can be used as raw materials in the industrial uses. It would be possible to extract silica elements from rice husks and straws by burning them in air because their main contents are organics. In the previous studies, a strong acid leaching treatment on rice husks before burning was carried out by using H2SO4, HCl and HNO3 to prepare high-purity silica materials. This was available to accelerate the hydrolysis of celluloses and hemicelluloses contained in rice husks, and remove the above metallic impurities. A strong acid leaching treatment, however, is significantly hazardous to environment and human life, and causes an increase of the process cost. In this study, the environmentally benign, harmless to human and economically effective process to produce high-purity amorphous SiO2 materials from rice husks has been established without using strong acids. From a viewpoint of the harmless influence on human body, the carboxylic acids were used in the leaching treatment on rice husks. TG-DTA measurement and GCMS analysis indicated that the leaching was effective for the hydrolysis of celluloses and hemicelluloses contained in rice husks at 473K~873K, which produced the same results in using the conventional sulfuric acid. The metallic impurities could be also removed from the husks via a chelate reaction between carboxyl groups (-COOH) and the metal elements. In particular, it was clarified that cadmium (Cd) were completely removed from rice straws by this reaction. Concerning the burning conditions of rice husks after the acid leaching, it was necessary to supply a suitable amount of air to completely combust organics; for example it required air supplement of 50 ml/min. or more. The burning temperature should be less than 1273K to obtain amorphous structured silica. High-purity amorphous silica materials with 99% or more were prepared from rich husks by applying the citric acid leaching treatment and burning process at 1073K in air.

Jan 1, 2008

By Guo-Sen Zhu

Research on the formation mechanism and control of corner transverse cracks was carried out. The optical microscope and SEM were applied to analyze the characteristics of cracks. It is found that the cracks occur at the relatively lower temperature due to unbending strain and have almost nothing to do with the mold cooling and powder. The keys to prevent corner transverse cracks are to optimize the corner temperature of slab and maintain the good state of casting machine. Increasing casting speed and decreasing the cooling water flux at the corner in the unbending segments, resulting in mild cooling, were applied during investigation to control corner temperature above the upper limit temperature of the No.3 brittle zone of Nb-contained steel tested by Gleeble-1500 system. As a result, corner transverse cracks were minimized, but centerline segregation got worse. And then increasing the cooling water flux at the corner (intensive cooling) was applied to make corner temperature below the lower limit temperature of the No.3 brittle zone. Great diminution of both corner transverse cracks and centerline segregation was achieved finally.

Jan 1, 2006

By Tugba Basargan Çagatay Morall, Gülhayat Nasun-Saygili

"The aim of this study is to prepare the apatitic material using colemanite mineral (2CaO.3B2O3.5H2O) which was obtained from Eastern Anatolia, Turkey. For this purpose, colemanite mineral was reacted with different phosphate sources, namely, dipotassiumhydrogen phosphate, ammoniumhydrogen phosphate and ortophosphoric acid at various temperatures and time periods. Experiments were run in batch system. The apatitic material was prepared by a wet method and followed by heat treatment at various temperatures. Structure of the samples was analyzed by XRD, FTIR, XRF and SEM. The particle size analysis was also made for the result product. The experiments showed that reaction temperature, contact time and heating temperature are important parameters to transform the colemanite into apatitic structure. Reaction of colemanite with dipotassiumhydrogen phosphate and ammoniumhydrogen phosphate results in amorphous, non-stoichiometric hydroxyapatite type structure, while acid based phosphate source gives brushite and monetite type product before and after heat treatment, respectively.IntroductionBoron which has properties intermediate between metals and non-metals is a member of semiconductor group of elements. Its atom is very small and has three valence electrons. Boron exists in Earth's crust (from 5 mg/kg in basalts to 100 mg/kg in shale) and in the oceans (4.5 mg/l) [1]. Turkey has 60% of world's boron reserves which is mostly in the form of colemanite (2Ca0.3B203.5H20). Colemanite is the most important calcium containing commercial borate mineral with 5 mol of crystal water [2].Calcium phosphate cements are very useful for bone repair applications because of its chemical structure. They are injectable, easy to shape and can be maintained locally. Because of those reasons calcium phosphate cements are very effective to fill bone defects with an irregular shape [3]. Hydroxyapatite (Ca10(PO)6(OHh) is the major component of the bone (70 wt%). However, hydroxyapatite stoichiometry, composition and crystallinity differ in human skeleton system [4, 5].The main objective of the present work was to study the transformation of colemanite to apatitic material using different phosphate solutions at several time spans and temperatures. The experiments were run in a batch system, change in pH and also weight loss were measured after the experiments. Several analysis methods were used to investigate the chemical and structural changes."

Jan 1, 2012

By Jiechao Liu, Lijian Luo, Yubao Ma, Bo Zhang, Yanfeng Yang, Xin Hong, Luming Liu, Jienan Liu

Reduction kinetics of stainless steel slag in iron bath smelting reduction was studied at the temperature of 1500℃ ~ 1650℃. It was concluded that the reduction process consisted of two parts. That is to say smelting reduction was controlled by stainless steel slag melting initially and by interface reaction later. In order to increase smelting reaction rate, the melting point of slag should be decreased at the first stage and adjust the liquidity of slag at later stage. Smelting reaction rate will be accelerated by means of optimize the slag content. The optimal reduction result that all most all of the chromium in slag been recovered was obtained in temperature was 1500℃, basicity of slag was 1.0~1.2, the value of Al2O3+MgO was 25%.

Jan 1, 2015

By Li Zhang

A novel green technology to recovery Titanium compounds from Ti-bearing blast furnace slag under the dynamic oxidation condition was developed and tested. Air was blown into the molten slag as oxygen resource through a lance during the dynamic oxidation process, in which six important results were found: (1) The TiC, (Ti2O3), Fe and (FeO) in the slag were oxidized; (2) The temperature of slag temperature rapidly increased; (3) The viscosity of slag decreased; (4) The coalescence, growth and drop of the metallic Fe droplets in the molten slag were carried out under an air agitation condition; (5) The dispersed Ti components were selectively enriched into the perovslite phase, and the perovskite phase could be selectively precipitate and grow. And also, the perovskite phase can be separated by the dressing method. The oxidation of molten slag gives off a large amount of heat, which helps chemical reactions proceed, improve the rate of chemical reactions, and promote the precipitation and growth of the perovskite phase. The features of the technique are clean, low cost and a great capacity to deal with a large quantity of slag. It was confirmed by experiments that the precipitation of the perovskite (CaTiO3) in molten slag is obviously affected by operation factors such as temperature, chemical composition, heat-treatment, additives and so on. The precipitating kinetics and mechanism of the perovskite phase from molten slag during the dynamic oxidation processes were also investigated.

Jan 1, 2006

By Cevat Serdar Kucukkaragoz

The kinetics of prereduction of Chromite by carbon was studied under argon atmosphere at temperatures between 1000°C and 1300°C . The compacted and agglomerated specimens were reacted by using a TGA system. The mixing characteristics and the degree of compaction of the chromite and coke particles were the main parameters influencing the reduction kinetics. The reduction rate increased with temperature reaching to 81% reduction at 1300°C. The metallization started as the metallic nucleation around the particles which was first observed at 1100°C. The particles were surrounded by the metallic phase at approximately 40 % reduction obtained at 1200°C. At 1300°C, the reduction proceeded with a high rate during initial stages and with a low rate at final stages. The reduction was found to proceed in the sequence of Fe3+to Fe2+, Fe2+ to Fe(metal) and Cr3+to Cr(metal) with the formation of carbides.

Jan 1, 2006

By F. Tailoka

In order to decrease the voltage required for electrorefining, a recessed electrode cell has been developed in which the anode and cathode have recesses machined into their faces. The anode and cathode plates are separated by a thin refractory cloth and the cell is filled with fused salt. Bismuth containing 10 to 90 % lead with copper and silver as minor impurities has been electrorefmed at a current density of 10,000 to 20,000 Am-2. The cell voltage was between 285 and 635 millivolts and the bismuth was refined to a purity of 99.9 %. Flow patterns were observed in a room temperature model of the recessed channel cell using water and mercury to simulate molten metal and the fused salt electrolyte. The flow in the electrode recesses is characterized by discrete droplets when the liquid flow rate is low and thin streams and rivulets at higher flow rates.

Jan 1, 1995

By Shize Jin

Effect of four polyols, namely ethylene glycol (EGL), glycerol (GCL), propanediol (PDL), butanediol (BDL) and three organic acids, namely oxalic acid (OA), malonic acid (MA) and succinic acid (SA) on the current efficiency (CE) and the cell voltage during zinc electrowinning was studied. Galvanostatic polarization was conducted in a supporting electrolyte (SE) containing 180 g dm-³ H2SO4, 60 g dm-³ Zn2+ and 8 g dm-³ Mn2+ at 38°C with magnetic stirring. The imposed current density was 50 mA cm-². The anodes were made of a Pb-Ag alloy and the cathodes were made of an aluminum alloy. The results showed that all the polyols tested in this study decreased the current efficiency and the cell voltage, but the decrease of the cell voltage was not important. Oxalic and succinic acids decreased the current efficiency to a less extent than the polyols, but did not decrease the cell voltage much. The only compound that increased the current efficiency was malonic acid, and its capacity of decreasing the cell voltage was the highest within the seven tested organic compounds.

Jan 1, 2003

By M. I. Kalashnikova

Gipronickel Institute has developed the technology of treatment of difficult to concentrate sulphide Pb-Zn concentrates (Zn-19,9%, Pb-8,4%, Cu-0,34%, Fe-8,8%, Ba-6,8%, S-18,7%, Ag-106 g/tonne). The technology consists of pressure leaching, impurity removal from leaching solution, electrowinning and Pb-Ag containing cake treatment. Despite low zinc content in initial concen-trate the technology allows production of solution which is suitable, after standard procedure of impurity removal, for electrowinning with production of zinc grade SHG. Comparing to the standard technologies the flowsheet developed provides the lesser expenses per zinc unit because of decreasing of liquid to solid ratio at pressure leaching stage. The initial concentrate is characterized along with low content of principal metals by high con-tent of barite, which makes flotation of pressure leaching residue more difficult. That is why in this case the hydrometallurgical treatment was chosen. At optimal parameters of chloride leach-ing found during laboratory experiments the principal components extraction was 99.5% for Pb and up to 92% for Ag.

Jan 1, 2006

By M. Arenas

A corrosion study of a bonded NdFeB permanent magnet materials alloyed with titanium carbide additions has been undertaken. The materials were produced by rapid solidification by melt spinning. Commercial epoxy was used as a bonding medium. The corrosion results were compared with those of a near stoichometric unalloyed NdFeB. Anodic polarization and potentiostatic techniques in 0.9 M Na2SO4 solutions were used to characterize corrosion behavior. It was found that the addition of 6 a10 Tic resulted in superior corrosion resistance, as indicated by lower corrosion currents and less iron dissolution at fixed potential.

Jan 1, 1997