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By Zdzislaw Miczkowski

At KGHM Polska Miedz S.A, a direct flash smelting process is used for smelting of chalcocite concentrate for the production of blister copper. The paper presents a model of complex oxidation process of single concentrate grains smelted at KGHM. The description covers main chemical reactions, phenomena of heat and mass exchange inside the grains and between a grain and the surrounding space. In the model, two zones describing the course of process inside the grain were distinguished: ? The first one, which moves faster towards the centre of a grain, both organic and carbonate carbon are freed, The process takes place without the presence of oxygen and results in an increase of the temperature in the core of the particle. ?The second zone moves slower into the grain and the rate of the movement is determined by the presence of oxygen, In that zone the sulphur is eliminated and the oxidation of the organic compounds vapours moving from deeper layers of a grain takes place. Based on the results of laboratory tests, the coefficients that describe the oxygen transportation into the grain and decide the progress in the chemical reaction were determined, The paper contains the results of model calculations for single grains reacting in environment of various content of oxygen as well as the results of model calculations for the laboratory reactor system.

Jan 1, 2003

By D. M. Jones

In May 1999 the first campaign of the BHP San Manuel flash smelting furnace (FSF) will be concluded after having set world records for both campaign length and tonnage smelted for an Outokumpu copper flash smelting furnace. This paper reviews planned process and equipment modifications including: The installation of a new 36,000 mt concentrate storage facility; replacement of the existing dryer electrostatic precipitator with a baghouse; modification of the FSF dry charge bin and feed system to achieve mass flow and uniform feed to the concentrate burner; modifications to the FSF and its ancillary cooling systems; modifications to the waste heat boiler and offgas handling system to increase gas handling capacity and improve process efficiency;- and improvements to the FSF fugitive gas collection system. A brief review of the planning and execution of the scheduled 45 day shutdown is also given.

Jan 1, 1999

By Mototsugu Matsuno

A new process has been developed to treat fly ash generated from municipal incinerators, which contains not only toxic metals such as lead and cadmium, but also dioxins. The process includes the following steps; fly ash is formed into green pellets with some additives and the pellets are then roasted to eliminate or stabilize the toxic metals and to decompose dioxins. A pilot plant with a capacity of approximately 100 kg/hr was used to test the process. The tests verified that heavy metals were either volatilized or stabilized and dioxins were decomposed by high-temperature roasting. The pelletized ash was found to be non-toxic, so that it can be recycled as artificial lightweight aggregate. It was also found that volatilized metals collected as secondary ash can be recycled as smelting resources.

Jan 1, 2003

By Kimio Itagaki

The distribution ratios of Ag, Pb, As, Sb and Bi for the Cu2S-FeS or Ni3S2-FeS matte / FeOx SiO2, FeOx-SiO2-CaO or FeOx-CaO slag equilibration in a MgO crucible were determined experimentally at 1523~1573K under controlled partial pressures of S2 and O2 at given PSO2 of 10.1, 50.7 and 101.3 kPa (0.1, 0.5 and 1 atm) and be observed dependency of distribution ratio on the matte grade, SO2 pressure and slag basicity were analyzed on the basis of thermodynamics,

Jan 1, 2003

By Yuan Lu, Yiming Rong, Richard D. Sisson Jr

With the development of quench technology, there is a trend of using gas quench to replace liquid quench for less distortion and residual stress. The fundamental difference between the liquid and gas quench is the heat transfer coefficient, not only the values but also the shape of the curve as a function of temperature. The equivalent heat transfer coefficient for the liquid and gas quench is analyzed by simulations and experiments. Even it may result in the same hardness in the liquid and gas quench, the steel microstructure may be different because of the different cooling processes, and therefore other steel properties, such as toughness, may be different. The cooling process, microstructures and properties such as hardness and toughness should be examined when designing the liquid or gas quench processes.

Jan 1, 2015

By C. Dupuis

Thiourea is a promising reagent for gold extraction especially from refractory ores that cannot be treated by traditional cyanidation route. In this study recovery of gold from thiourea leaching solutions was investigated by direct electrowinning. The electrolysis cell consisted of a carbon flow-through cathode and a lead anode. The anodic and cathodic compartments were separated by a membrane. Galvanostatic mode was chosen for operation of the cell. Factors affecting recovery efficiency such as cathode thickness, linear flowrate, current intensity, thiourea and gold concentrations were investigated. The influence of some species in solution on efficiency and selectivity of recovery was investigated. Gold recovery reached 99% but current efficiency was lower than 10%. The complex formed with ferric ion and formamidine disulfide are reduced before gold-thiourea complex. Thiourea consumption occurred during leaching mainly by oxidation and reaction with dissolved copper.

Jan 1, 1989

By QinGuo, Shenghui Guo, Lei Li, Jinhui Peng, Linqing Dai, Libo Zhang

The ferrous removal process after carbothermic reduction of chromite fines with microwave heating combined with leaching was investigated. Under the following conditions: Reaction temperature: 1150 , Reaction time : 40min, Semi coke ratio: 12% , the iron content of the reduction product : 13.05% . Metallization achieved was 52.7%. Reduced chromite was leached with 8% of H2SO4 and FeCl3 aqueous solution. The results show that: the recovery rate of chromium can reach 88.06%, the mass ratio of chromium to iron is 3.5:1 for leaching 30 minutes with 8% of H2SO4; the recovery rate of chromium can reach 88.91%, the mass ratio of chromium and iron is 2.56:1 for leaching 4h at room temperature with FeCl3 aqueous solution (100g/L). The leaching time of latter is longer but can realize the circulation effectively and reduce the waste liquid processing problem.1

Jan 1, 2016

By Muhammad Abid, Kh. .. S. Karimov

"In this study, design and investigation of biogas digester consisting of methane tank with built-in solar collector to utilize solar energy for the heating of the slurry prepared from the dung and heat exchanger is designed, developed and tested. The digester was laboratory type and consists of cylindrical metallic tank of size of 0.5 m in diameter; 1 m in height and 200 liters in volume. The surface of the digester from outside was covered by thermo insulated material a glass wool, except of south side (in northern hemisphere). This side played the role of built-in collector and was blackened to increase absorption of solar irradiation and covered under 45o by glass. In the blackened side of the digester on the different heights it was installed metallic pipes for the inlet and outlet of the air, connected with heat exchanger installed inside of the digester. The heat exchanger was fixed in the level above of the inlet pipe. The horizontal plane reflector concentrates solar beams to blackened side of the digester. In the winter period, it was found that the retention time of this digester is shorter on 15% and produced biogas volume is larger on 20% with respect of ordinary biogas digester. This digester is used for the demonstrative purposes and as a teaching aid presently and base on the results it may be used for the construction of large volume digesters for use in the farms, especially located in the remote and mountain areas where the climate in the winter period is cold. Introduction At present many experts around the world have focused their efforts to energy crises because energy is one of the most important factors for the development of the society. It is known that consuming energy is proportional to quality or standard of life. There is a close relationship between energy consumption and the Gross National Product (GNP). It is obvious that for further development of the country additional sources of energy is required, which are cheap, safe and environmentally compatible with respect to the action on possible wastes. Utilization of renewable energy is one route to help in solving the above mentioned problems. In particular, biogas as a source of renewable energy is produced by biotechnology and used wide on residential scale [1]. The biogas was produced for the very first time in 1814 by Deivy from organic wastes. In 1900 production of biogas was started in Bombay (India) [2, 3]. Biogas consists of 55-70% methane (CH4) and around of 27-44% carbon dioxide (CO2) and less than 1% H2 and H2S. At present biogas is used widely in some countries for lighting, machines, and vehicles, generators, cooking and heating. Biogas generation is suitable for small to large scale operation and at present is realized in a number of developed and developing countries as USA, Hungary, China, India etc. Since 1990s biogas projects construction in China has developed steadily by the end of 1998, there were altogether 6.88 million household biogas digesters [4]. In Russia biogas digesters are used for processing of hard dung into biogas [5]. Over the last few years the very first biogas digesters were constructed in Tajikistan as well [6,7] and it was found that the digesters can work with sufficiently high efficiency in mountain areas as well ."

Jan 1, 2008

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 S02 in the flash furnace. Preliminary experiments were conducted in a miniplant 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 Jayagopal Ucbil, M. Krishna, V. T. Vijayalakshmi

"The pitting susceptibility of aluminium metal matrix composites reinforced with garnet particles has been examined using static weight loss method by exposing the metal matrix composites (MMC) specimens to the action of IN HCI acid at laboratory temperature for different time intervals. It was found that the corrosion rate decreased with increase in weight percentage of reinforcement while the corrosion rate was a function of the matrix alloy but not of the reinforcement material. Further, it was found that the rate of corrosion was dependent on the interface region formed between the reinforcement and the matrix. A comparison of the base matrix with the corresponding composite when subjected to heat treatment for varying periods of 4, 8, and 12 hours respectively was made. The comparison revealed that corrosion resistance of the composite increased with the duration of heat treatment and this has established a considerable improvement in corrosion resistance of the composite when compared with the base matrix.IntroductionMetal matrix composites (MMCs) offer designers many added benefits, as they are particularly suited for applications requiring good strength at high temperature, good structural rigidity, dimensional stability, and light weight [1-5]. The trend is towards safe usage of the MMC parts in the automobile engine, which work particularly at high temperature and pressure environments [6-7]. Particles reinforced MMCs have been most popular over the last two decades. Among the MMCs, the most popular families are represented by aluminium reinforced with ceramic particles. Although the incorporation of the second phase into a matrix material can enhance the physical and mechanical properties of the base metal, it could also significantly change the corrosion behavior."

Jan 1, 2000

By C. Kathryn Sole

The close proximity of cobalt and nickel on the Periodic Table and their frequent occurrence together in nature means that their separation in primary hydrometallurgical flowsheets is not only often necessary, but requires the use of innovative chemistry to achieve high selectivity. Today, increasingly stringent demands for the high-purity cobalt and nickel salts required for battery applications in consumer electronics, electric vehicles, and solar applications are again challenging the state of the art. The evolution of cobalt–nickel separations is traced from the basic precipitation technologies employed in 1960s, through commissioning of the first cobalt solvent-extraction plant in South Africa in 1974, to the commercialisation of organophosphinic-acid extractants (which provided a step-change improvement in selectivity) and their eventual widespread use in the 1980s and ’90s. This was followed later by their sulphur analogue, which enabled different possibilities for laterite processing in the new millennium. Separations in chloride media, which take advantage of the different speciation chemistries, and nickel extraction by oximes in ammoniacal systems are also discussed. More recently, chelating and solvent-impregnated resins have added further dimensions to the possibilities for flowsheet design and enabled higher purity products to be attained from both primary and secondary sources. Selected case studies and flowsheets are described.

By Zdzistaw MiGzkowski

At KGHM Polska Miedi S.A. a direct flash smelting process is used for smelting of chalcocite concentrate for the production of blister copper. The paper presents a model of complex oxidation process of single concentrate grains smelted at KGHM. The description covers main chemical reactions, phenomena of heat and mass ex-change inside the grains and between a grain and the surrounding space. In the model, two zones describing the course of process inside the grain were distinguished: ? The first one, which moves faster towards the centre of a grain, both organic and carbonate carbon are freed. The process takes place without the presence of oxygen and results in an increase of the temperature in the core of the particle. ? The second zone moves slower into the grain and the rate of the movement is deter-mined by the presence of oxygen. In that zone the sulphur is eliminated and the oxidation of the organic compounds vapours moving from deeper layers of a grain takes place. Based on the results of laboratory tests, the coefficients that describe the oxygen transportation into the grain and decide the progress in the chemical reaction were determined. The paper contains the results of model calculations for single grains reacting in environment of various content of oxygen as well as the results of model calculations for the laboratory reactor system.

Jan 1, 2003

By Selvin Yesilay, Guray Kaya, Bekir Karasu, Asli Cakir

"In this investigation, the wastes of Eti Maden Kirka Boron Company of Turkiye were evaluated in the production of diopside and anorthite-based glass-ceramic glazes suitable for porcelain tiles fast and single-fired under industrial conditions. First of all, high wear resistant frits were produced with the use of concentrator and derivative borax wastes. Second of all, pre-engobed porcelain tile bodies were coated with the standard and newly produced frit-based glazes and industrial fast single-firing was employed. Final products were undergone to the certain standard tests to determine their Vickers hardness, wear resistance, thermal expansion coefficient values, gloss and coloring parameters. The micro-structures and phase formations of the fired glazes were also studied. Consequently, it was confirmed that the utilization of borax solid wastes in fast single-fired porcelain tile glass-ceramic glazes is possible. Introduction Porcelain tiles were introduced at the end of 1980s by Friandre, one of the leading Italian porcelain manufacturers. The American National Standard Specifications for Ceramic Tile defines porcelain tiles as: dense, smooth, impervious (with water absorption value less than 0.5 %) and stain resistant [1]. The excellent technical performances for ceramic tiles, such as mechanical, wear, frost and chemical resistance that make their use possible in indoor and outdoor building applications [2-3]. In the last decade, the growth rate of the global production of porcelain tiles increased more than those of other ceramic products; in fact, the technical properties of porcelain tile, coupled with even more improved aesthetic appearance, gave it a prominent role on the tile market [2]. Glass-ceramics are composed materials of one or more crystalline phases immersed in a residual glassy phase [4-5]. Glass-ceramic technology is based on controlled nucleation and crystallization of bulk glass [6]. The concepts of controlled crystallization of glass designate the separation of a crystalline phase from the parent glass in the form of tiny crystals. Their growth rate and final size are controlled by a suitable heat treatment [7]."

Jan 1, 2008

By Sepideh Abolghasem, Juan Pablo Casas Rodriguez, Juan Camilo Osorio

Predicting flow stress at high strain-rates is a desirable practice for material behavior characterization. Sub-grain size has shown a huge influence in cutting forces and the workpiece surface finish determination during orthogonal cutting process. Hence, a prediction of flow stress as a function of thermomechanical conditions and sub-grain size is of great important which is studied in this work for OFHC copper. The principal thermomechanical conditions being strain, strain-rate and the accompanying temperature rise are characterized in Plane Strain Machining (PSM) and the resulting microstructure, sub-grain size, is quantified. Material maximum flow stress (a constitutive model) as a function of thermomechanical conditions and sub-grain size is predicted considering a saturated state in microstructure using optimization algorithms for reaching the validated temperature rise based on modified Hahn’s model. Evaluated models suggest a major influence of strain-rate and dislocation in temperature rise estimation and flow stress prediction leading to consideration of mechanical failure phenomenon involved in machining-based manufacturing processes.

Mar 1, 2018

By W. R. McDonald

The U.S. Bureau of Mines investigated treatment of gold and silver refractory ores and concentrates that respond poorly to conventional cyanidation techniques due to the complex mineralogy of the ore. Three types of ores were investigated: gold locked placer sands, gold locked in sulfides, and gold that is robbed from the pregnant cyanide solutions by minerals in the ore. Ore treatment included grinding, flotation, cyanidation, air oxidation, pressure oxidation, hypochlorite oxidation, roasting, and carbon in leach.

Jan 1, 1991

By H. Y. Sohn, M. K. McCarter, Bradley C. Paul

"A computer model was constructed for bacterial leaching of the major sulfides found in porphyry deposits, including bornite, chalcocite, chalcopyrite, covellite, cubanite, enargite, native copper, pyrite, and pyrrhotite. The model incorporates equations for the sulfide minerals dispersed in the rock matrix. Leaching occurs by reactions with ferric ion diffusing into the rock fragment: Ferrous ion is resenerated to ferric with oxygen by bacteria at a temperature dependent rate. The model keeps track of the net acid generated, oxygen consumed by the bacterial oxidation of ferrous ion, heat generated, jarosite and hematite precipitated, and copper leached. The model was used to predict the rate of copper recovery, heat generation and oxygen demand for a variety of run-of-mine sized porphyry ores. These results were used in the design of a ventilation system and the economic analysis of a modified in situ extraction method that may be cost competitive with conventional copper production involving open pit mining.IntroductionA study was undertaken at the University of Utah to evaluate the technological and economic feasibility of mining copper by a method referred to as Flood Drain Leach Cell (FDLC) mining. Cells 60 by 75 meters in plan and 70 meters in height are created throughout the ore body by a modified Vertical Retreat Mining technique that includes the removal of 25% swell material. The swell material is leached in finger dumps on the surface while the cells underground are bulkheaded, flooded, drained, and artificially aerated to promote bacterial ferric sulfate leaching. Solutions are cycled through several cells to reach pregnant grade of 1 gram copper per liter of solution. These solutions are then fed to an underground solvent extraction plant and then a surface electrowinning tankhouse."

Jan 1, 1988

By XING Xiangdong, Zhang Jianliang, MA Jinfang, WANG Zhenyang

The non-equilibrium reflux reaction behavior of phosphorus was studied with synthetic slags formed by using the AR chemical reagents and changing the initial condition of basicity, FeO, MgO and Al2O3. Due to increase of viscosity, the dephosphorization slag with high basicity inhibits the full contact of slag with iron, which leads to the low reaction rate in the early stage. However, since the high basicity improves the activity coefficient of CaO, the dephosphorization rate and phosphorus capacity goes up in late reaction stage. FeO promotes the increase of reaction rate in early dephosphorization stage. But the polarization force of Fe2+ is stronger than Ca2+, which hinders the reaction between phosphate ion and CaO and reduces the stability of PO4 3-. Thus, high content of FeO will adversely impact on dephosphorization reaction. In addition, MgO has a promoting effect to the dephosphorization, whereas Al2O3 has a negative influence.

Jan 1, 2016

By Lv Guozhi, Niu Liping, Liu Yan, Zhang Zhiqi, He Jicheng, Zhang Ting’an, Dou Zhihe

"CuCr alloy can be extensively used as contact materials in integrated circuit, electrodes, electric contact and high strength conductor. We proposed thermit reduction-electroslag remelting method of preparing the large scale CuCr alloy. But there are pores and oxide inclusions in CuCr alloy prepared by thermit reduction process. This paper studied mainly the effects of ratio of reactant and additive on the inclusion type and their occurrences in CuCr alloy. The slags and CuCr alloy were characterized respectively by XRD and SEM. The results show that when the additive is Na3AlF6, the slag consist of Al2O3 and Cr. When the additive is CaF2, the slag consist of Al2O3, Cr, CaF2 and CaAl4O7. The inclusions in CuCr alloy are mainly Al2O3 and pores which disperse in Cu-rich zone and Cu-Cr phase interface. When 5% CaF2 and 5% KClO3 are added, there are fewer pores and inclusions, and the more better microstructure.1 IntroduceCuCr alloy is the contact terminal material with an eximious properties[1,2], which gradually replaces CuBi alloy becoming the first choice for contact terminal material in the medium and high power vacuum switch after the 1970s. The traditional preparation methods of CuCr alloy mainly contain powder metallurgy, infiltration process and vacuum electric arc melting methods. But the above methods exist some shortcomings, such as poor product quality, high cost of production, processes complex ect[3-9]. CuCr alloy is made by the thermit reduction self-propagating method, which uses CuO, Cr2O3 and Al as raw material to get the high-temperature melt, and then casts to manufacture CuCr alloy ingot, which response equation follows as:"

Jan 1, 2012

By A. Rojo, N. J. Ramirez, J. E. Salgado

"This work aims to characterize the plastics used in a handgrip located in the car interior body in order to improve its design process and be able to predict its behavior when the part is subjected to impact test involving human casualties.Through stress analyses at high speeds and a video camera set up (front and side view), the reduction of area of specimen was obtained from image analysis, allowing to get the stress-strain real curve of the material.Continuing the characterization process a set of impact test was developed, where standard lzod configurations were used in unnotched specimens. From these tests were gotten displacement curves and absorption energy estimations.The proposed testing procedure allowed the acquisition of force and displacement data through time at various strain rates which are indispensable for the characterization of dynamic events. Using a specimen with a special configuration has shown a more detailed dynamic behavior resulting into more accurate numerical analyses within the design process.IntroductionIn the design process, one of the many analyses which take place is the impact test of the designed part. Nowadays there are many software capable to do these kind of analysis and each industry use the one they think it is convenient for them, but also the selected software has mathematic models that help to find the solution and the simulation of the case of analysis. These are not the only considerations that a company has to take into account, other one is the type of information and data necessary to feed the software. For this study we are going to focus on the acquisition of these data.The mail reason of this work is that generally the supplier gives the card of the material with all the characteristics and information requested by the buyer, but all of that information is acquired by standard methods, but it is inconvenient when the materials are polymers."

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