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By Eugene Jak

Copper sulphide processing technologies face increasing pressures associated with decreasing concentrate grade leading to increasing thermal inefficiency and lower productivity. Impurity concentrations are on average increasing, creating potential environmental risk and additional treatment costs. In copper flash smelters dust, partially oxidised materials and fume formed from the condensation of volatile impurities, are routinely recycled to the feed. In the converting stage the heat balance is maintained by charging anode reverts and other inert materials. In both cases, the thermal energy available from sulphide oxidation is not fully utilised or optimised. The productivities of both smelter and converter stages can be potentially increased through the addition of a high copper, low iron, low impurity precipitated copper product. Calculations are carried out for fayalite smelter and calcium ferrite converter slags using an optimised FactSage thermodynamic database. The potential for significant increases in smelter and converter productivities using existing technologies are predicted.

By Zhenyang Wang, Yiran LIU, Xiangdong Xing, Jianliang Zhang, Zhengjian Liu

Basic characteristics of marine placer were systematically studied by chemical analyze, scanning electron microscope and X-ray diffraction in this paper. It could be found that the marine placer mainly consists of titanomagnetite and titanohematite. A series of experiments were performed to investigate reduction-magnetic separation for Fe and Ti from the marine placer. Effects of reduction temperature, reduction time, carbon ratio, magnetic density, and grinding fineness on the reduction-magnetic separation process were investigated. And the optimal process parameters were obtained as follows: the reduction temperature 1300, the reduction time 30 min, the carbon ratio 1.1, the magnetic density 50mT, and the grinding fineness of 0.074μm 86.34%. Under such conditions, the metallization rate, iron grade of magnetic substance and iron recovery reached to 94.23%, 97.19% and 90.28% respectively, and the titanium grade in non-magnetic substance and recovery of was 57.94% and 87.22% respectively. The effective separation of iron and titanium could be achieved in reduction-magnetic separation process.

Jan 1, 2015

By Asmo Vartiainen

The viscosity of liquid Fe-O-SiO2 -slag at copper smelting conditions was investigated using a rotational viscometer. The studied parameters were oxygen partial pressure (10" °-10"6 bar ); composition of slag (Fe/SiO2 ratio), and temperature (1250-1400°C). The viscosity values are presented as a function of Fe/SiO2 ratio and as isoviscosity curves in ternary FeO-Fe2O3-SiO2 diagrams. The increase in viscosity at high silica contents can be accounted for the polymerisation effect of SiO4/4- -anions. At high ferric iron contents, higher oxygen partial pressure, the viscosity values increase especially near the magnetite saturation. The viscosity values are highest at the double saturation of silica and magnetite. At lower silica and ferric iron contents the viscosity values are more uniform in the homogenous liquid slag area. The viscosity values were lowest at high temperatures and highest at low temperatures.

Jan 1, 1998

By A. D. Zunkel

Increasing amounts of electric arc furnace dust (EAFD) are being generated worldwide as more steel is produced from electric furnace melting of galvanized steel scrap. In most countries, the management of this material is a costly technical, economic, and legal problem for minimill steelmakers. Many technologies and processes are being developed and implemented worldwide to manage this material to recover contained zinc, lead, and iron values and render it nonhazardous. These processes are pyrometallurgical, hydrometallurgical, or hybrid in nature. Some produce zinc oxide, some zinc metal, some lead metal, and some lead cement. Some are successful, some have failed, many are dormant. or abandoned, and others continue to be developed and emerge. This paper updates the current status of 20-30 processes in various stages of commercial application and development used worldwide to manage EAFD and recover its nonferrous, particularly zinc and lead, and ferrous values.

Jan 1, 2000

By Marco A. S. Aguiar, Luis G. S. Sobral, Vânia Mori, Paulo A. Medeiros da Silva

"Copper occurs in the crust of the earth, predominantly, as sulphides. Among the copper sulphide minerals, the chalcopyrite is the most abundant and the most refractory to the conventional oxidative processes. This work aims at developing an electrolytic process for treating a copper sulphides flotation concentrate, more precisely chalcopyrite (CuFeS2) and bornite (Cu5FeS4) in the percentages of 70 and 30%, respectively.This paper presents a low-cost operational electroleaching process for treating copper sulphides flotation concentrates, with a high chalcopyrite content. This research practical work aims at improving the copper extraction from that sulphide mineral, in a relatively short time with low-operating cost taking into consideration the influence of a cationic surfactant. The electrolyte of the electrolytic reaction system was a 2,0 mol.L-1 NaCl solution containing CTAB, a cationic surfactant. The electroleaching system contains one DSATM (dimensionally stable anode) anode and two nickel or copper foams (threedimension electrodes. During the electroleaching process the chloride ions are oxidized to chlorine at the anode surface, which in contact with the aqueous phase generate enough hypochlorite ions to oxidize chalcopyrite.The copper ions released from the chemical oxidation process are reduced at the cathode surface as metallic copper."

Jan 1, 2008

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 Susana Caballero, Lourdes Yurramendi

Air Pollution Control (APC) ashes from Municipal Solid Waste Incineration (MSWI) plants need to be treated prior to landfilling due mainly to their heavy metals content. This research evaluates the capacity of the APC residues to sequester carbon dioxide, while the ash becomes stabilized for storage. It has the benefit of using two wastes, with no addition of any raw material. APC samples from different MSWI plants were treated by gas/solid accelerated carbonation at different temperatures and carbon dioxide concentrations to evaluate the residue behaviour to the process. The extent of carbonation was evaluated by means of weight gain upon carbonation and by the measurement of the final carbonate content. The APC residues were analyzed before and after the treatment in order to know their composition and their leaching behaviour according to the criteria for the acceptance of wastes at landfills established by the European Council Decision 2003/33/EC.

Jan 1, 2008

By Lucas Barbosa de Souza Martins, Frederico Muylaert Margem, Nathalia Carneiro Garcia Rosa, Sergio Neves Monteiro

"A natural banana fiber extracted from the plant pseudostem has shown values of density and mechanical strength with potential for uses in engineering applications such as automobile interior parts and floating components. Moreover, natural fibers can also be used as insulating materials in packaging and building panels. In this case some thermal properties are required. Therefore, the objective of this work was to evaluate the thermal behavior of the banana fiber by means of TGA, DTG and DSC analysis. The TGA curves revealed weight loss related to release of humidity and molecular structure decomposition. Peaks in the DTG curves indicated two intervals in temperature associated with different decomposition processes. The only endothermic DSC peak found was attributed to the lignocellulosic water of hydration being lost around 121°C.IntroductionIn recent times, environmental aspects related not only to pollution caused by non-degradable synthetic leftovers, specially polymeric wastes, but also to climate changes as a consequence of industrial activities, are motivating the use of natural materials. A particular case is fibrous composites, like the fiber grass composites. These synthetic materials, made from non-renewable polymers, are practically non-degradable and contribute to global warming by the CO2 emission associated with the energy required for the fabrication process. In spite of these environmental shortcomings, fiber materials are essential for the production of many items such as insulating chests, automobile cushion, construction panels, etc. An environmentally correct alternative to replace synthetic fibers composites is the naturally existing ones extracted from plants such as ramie and sisal. These have some environmental advantages of being renewable and degradable, these banana plant provide a negative contribution to C02 emission by absorbing greenhouse gas during the plant life cycle. Banana fibers have been used since long time in simple items such as ropes and rugs. Today they are used in engineering applications related insulation in building panels [2] and finish parts in automobile interior components [3]."

Jan 1, 2012

By H. Kurama

In this paper, utilization of fly ash as a value added product in areas such as novel materials, waste management, fillers and agriculture is reviewed with the aim of helping the expand of the usage of fly ash and reduce the environmental and economic impacts of disposal. The used unburned carbon benefication/treatment methods such as low temperature combustion, froth flotation, partical size classification and electrostatic separations to remove unburned carbon particles from fly ash are also discussed.

Jan 1, 2006

By Yahui Feng, Zhiwen Wu, Chen Chen, Xin Hong

Large amounts of copper slag containing about 40 wt% iron is generated during the process of producing copper. Recovery of iron from the copper slag is very essential not only for recycling the valuable metals and mineral resources but also for protecting the environment. The purpose of this study was to investigate the possibility of separating fayalite by oxidation-reduction process into Magnetite and silicate phases in intermediate temperature condition. Experimental results show that when the oxidation reaction at 1000℃ for 120min and the oxygen flow is 0.1L/min, most fayalite decompose to hematite, less part of magnetite and silica. And then, the mixture of carbon and oxidation product is pressed into blocks and reduced to magnetite and silica at 900℃ for 90min. A magnetic product containing about 57.9wt% iron was obtained from the magnetic separation under a magnetic field strength of 100 mT.

Jan 1, 2015

By Takashi Nakamura, Kenji Oosumi, Kazuhisa Fujisawa, Takayuki Kogishi

"Recycling of used aluminum beverage cans(UBCs) is one of the important issues for aluminum manufacturer presently. The direct re-melting of UBCs shows two problems. One is a reduction in molten aluminum recovery and the other is a contamination of other metals such as Ti and Fe from paints. Both problems are caused by paints coated on the surfaces of aluminum cans. Removal technique of the paints, therefore, has been required. Although roasting and shot blast techniques have been developed, both were not successful in removing the paints effectively. A swell-peeling method has been applied to remove them using a methylene chloride solution with acids and it works very well. Small laboratory scale tests have been carried out to develop the commercial process and clarify the mechanism of the swell-peeling method in the present study.When the surface area of UBC is more than 10 cm2, peeling time is independent of the surface area, about 60 seconds, because swelling phenomenon is controlled by the penetration of the liquid through the fine pits on the surface of the paint. This is good for a commercial process. Peeling takes place when the swelling force generated by methylene chloride exceeds the adhesion force between the film and the surface of aluminum, that is weakened by the coexisting acid, especially halogenated acetic acid."

Jan 1, 2000

By Peng Bing

Stainless steelmaking dust is classified as a hazardous waste due to higher than acceptable heavy metal leachabilities such as zinc, lead, cadmium and chromium. In addition to being an environmental hazard, the flue dust is also an economical concern to stainless steelmakers as it contains large amounts of valuable alloying elements, especially for iron, chromium and nickel. A new technology of direct recycling of stainless steelmaking dust has been developed to recover the metals from the dust. But it was found that zinc was accumulated in the dust collection system in practical run of direct recycling. This study focuses on the effect of the operating parameters such as temperature, dust feed rate and the ratio of CO to dust on the reduction of zinc oxides present in the dust. The mathematical model for the reduction process was setup based on the experimental research. According to the mathematical model, the temperature has obvious effect on the reduction of zinc. It is benefit to the process of zinc reduction to increase the temperature. But the temperature will not be the main factor for the reduction process after 1228C. It will promote zinc reduction to decrease the dust feed rate and control the ratio of dust to CO. It was also found from the experiments that ZnFe2O4 in the dust could be decomposed at high temperature. Decomposing ZnFe2O4 in the dust increases the recovery of zinc from the dust distinctly.

Jan 1, 2006

By Xavier Kleber, Aude Lamontagne, Veronique Massardier, Daniele Mari

"The thermoelectric power (TEP) technique was used to determine with high accuracy the strain ageing kinetics in heavily cold drawn pearlitic steel. Because of the very high sensitivity of the TEP to solute atoms, this technique allowed the strain ageing to be followed from the very first moments. The kinetics were followed during isothermal ageings performed between 20°C and 200°C for different strains. In order to avoid any ageing at room temperature, the samples were kept at -80°C immediately after cold drawing. TEP evolution versus strain highlights cementite decomposition occurring during cold drawing. During the ageing, a redistribution of the dissolved carbon atoms in ferrite occurred. The TEP increase with the ageing time was attributed to the departure of carbon atoms from ferrite (segregation to dislocations and/or carbide precipitation). The kinetics were analysed using the Johnson-Mehl-Avrami-Kolmogorov approach which enabled to determine activation energies associated with carbon atoms redistribution.IntroductionHeavily cold drawn pearlitic steel wires are commonly used as structural materials for their high strength and their acceptable ductility. However, several previous studies highlight the microstructural destabilization of pearlite mainly due to cementite decomposition during the drawing process, which induces changes of mechanical properties [1, 2]. This phenomenon was detected by several experimental techniques such as Mossbauer spectroscopy [3, 4, 5], themomagnetic analyses [6, 7], TEM [8, 9, 10] or atom probe tomography [9, 10, 11]. Nevertheless, the mechanism of cementite decomposition is still unclear. Several hypotheses were proposed in the literature. The first hypothesis relies on a strong interaction energy between carbon atoms and dislocations involving higher binding energy than that between carbon atoms and iron atoms in cementite [3]. The second hypothesis is the increase of the free energy of the interface between cementite and ferrite due to the fragmentation of cementite during deformation (Gibbs-Thomson effect) [8]. Some authors even suggest that the dissolution of cementite occur during a post-deformation ageing [12, 13]. It is worth"

Jan 1, 2013

By T. Goda, H. Kiuchi, M. Iguchi

"IntroductionThe utilization of silver in the electronic industry has been increasing in recent years. It is desirable that valuable metals are recovered from the used scraps of these industrial goods. Condensor chips, for example, contain silver, palladium, and Ag-Pd alloy. The dissolution behavior of silver was studied assuming that scraps such as used condensor chips in which Ag-Pd paste is used are subjected to wet treatment.ExperimentalIn this study the powder, granules, and flakes of silver were used in these nitric acid leaching experiments. The nitric acid solution was agitated in a glass reactor with a magnetic stirrer and heated to the required temperature. The experiment was started by putting the silver sample in the solution. After the leaching, the solution was filtered and the concentration of silver in the filtrate was analyzed by ICP.ResultsIn dilute nitric acid of less than 5 N, silver powder dissolved easily with increase in the concentration of nitric acid and temperature. However, the more intensive the stirring of the solution was, the lower the dissolution quantity became. Fig. 1"

Jan 1, 2000

By Chenhui Liu, Ka-ma Huang, Hong-ying Xia, Bingguo Liu, Hua Chen, Jinhui Peng, Libo Zhang

"The rising popularity of microwave heating in mineral processing has fuelled the need for knowledge concerning dielectric properties of minerals. Dielectric property and microwave absorption property of anthracite were measured over a temperature range of 20-100°C at 2.45GHz by using an open-ended coaxial sensor measurement system. The results show that the dielectric constant, loss factor and loss tangent increase with temperature rising at 2.45GHz. Microwave absorption properties of anthracite are highly dependent on temperature and frequency. At frequency of 2.45GHz frequency used in microwave metallurgy, anthracite is suitable for reducing agent to achieve fast elevation of temperature then returning to original state. The research will be helpful in explaining the thermal running of microwave dielectric heating the anthracite.IntroductionThe application of microwave heating in minerals processing and treatment has recently attracted great interest from the metallurgical industry. Compared with conventional heating methods, the advantages of microwave heating include rapid and selective heating, uniform distribution, high efficiency, fast on and off switching as well as flexible and modular design[l-3]. As a result of these advantages, microwave heating has been applied in a variety of mineral processing and extractive metallurgy, such as microwave-assisted ore grinding, microwave heating for carbothermic reduction and acid leaching of ilmenite ore, microwave drying, microwave-assisted roasting and smelting of sulfide concentrate, microwave-assisted spent carbon regeneration and microwave-assisted waste management [ 4-6]. Though the application of microwave heating in the metallurgical industry is promising, further studies on the interaction between microwave radiation and minerals and its effects are highly desired to develop innovative techniques for minerals processing and ore treatment using microwave heating [7]."

Jan 1, 2013

By Qingwei Qin, Ping Xue, Guangqiang Li

Ausmelt furnace slag contains about 0.9% Cu (mass %). With increasing the amount of Ausmelt furnace slag, the recovery of copper from it will produce an enormous economic yield. The recovery of copper by floatation from slow cooled Ausmelt furnace slag was studied in this paper. The phases and composition of the slow cooled slag were analyzed. The factors which affected the copper recovery efficiency such as grinding fineness, pH value of flotation medium, different collectors and floating process were investigated. It was shown that the size distribution of the primary grinding and secondary grinding of middling were 75% for particles less than 0.074mm and 82% for particles less than 0.043mm respectively. The closedcircuit experimental results with butyl xanthate as collector in laboratory showed that the copper grade reached 16.11% and the recovery rate of copper reached 69.90% and the copper grade of tailings was only 0.2%.

Jan 1, 2015

By P. Barrios

Over a period of one year, an in-depth investigation was carried out in a conventional copper refinery to understand the behaviour of silver in copper electrolysis. The increase in silver content in the cathodes increases almost linearly with the duration of electrolysis, and the silver content of the electrolyte between the electrodes shows similar behaviour. The silver content of the cathode deposited daily depends directly on the silver concentration of the electrolyte and this, in turn, is strongly influenced by its internal temperature. The average temperature between the electrodes rises from the first to the second and to the third crop, because of the increase in the distance between the electrodes and the heat generated by the passage of the current. The mechanism of dissolution of silver from the anode, and its passage to the cathode, are discussed. Following the change to the Isa system, it was proved that the results and conclusions are analogous. Based on these results, a reduction of more than 20% in silver losses in the cathodes was achieved.

Jan 1, 1999

By Keith E. Forrester

This paper presents results of bench scale laboratory evaluation of a processes developed by FESI and Brookhaven National Laboratories for the extraction and recovery of Pb and other heavy metals from incinerator ash which was subsequently modified by FESI for the extraction and recovery of Pb from soils excavated from a FESI client scrap yard and battery breaking operation facility. The specific waste matrix presented within the paper is a battery acid contaminated surficial soil at 0" to 12" depth. The extraction method was found to be highly successful on the bench scale in generating a final post-extracted soil matrix which passed TCLP Pb regulatory limits and retained minimal Pb after aggressive extraction application. The paper findings at this time are brief, as a majority of the research results are currently being compiled and additional efforts are underway based upon initial screening findings.

Jan 1, 1995

By Marcelo Jimenez Bustos

The Chagres Smelter was the first in Chile to follow environmental regulations to control sulfur dioxide emissions. Because of this, the operation and development plans have had to incorporate environmental planning as part of its policies for almost three decades. The present article shows the development of the environmental standards applied to its operations, investments and operational improvements carried out to meet the regulations and improve competitiveness. Results to-date and future plans are outlined, as well as their impact on operations and the environment.

Jan 1, 1993

By Torben L. Edens

Norddeutsche Affinerie is the largest copper producer in Europe. Two sites are in operation for the production of refined copper: primary copper production is located in Hamburg and secondary copper production in Lünen. A total of just under 560,000 tonnes of copper cathodes is produced annually at the two sites. Primary copper production using the flash smelter furnace has been in operation in Hamburg since 1972. Over the years, the capacity of the flash smelter has been increased in three expansion projects from 120,000 t to almost 500,000 t of anode copper p.a. The anode sector consisting of two anode furnaces and a 24 mould casting wheel still features just about the same equipment as in 1972. The paper describes the most important steps taken to optimise operation which have put NA in a position to cast meanwhile more than 500,000 t of anode copper annually with the two anode furnaces and 24 mould anode casting wheel.

Jan 1, 2006