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By Ovidiu Pasca

The Phelps Dodge Miami Smelter utilizes four Hoboken converters to process molten matte from the Isasmelt vessel. This paper presents past and present improvements in operation, maintenance and process optimization, based on data collection, which has led to increased converter campaign life and copper throughput.

Jan 1, 2005

By Xuemei Zheng, Aiyuan Ma, Chao Liu, Guojiang Li, Chenyu Sun, Jinhui Peng, Libo Zhang, Yongguang Luo

In this paper, the removal of fluorides and chlorides from blast furnace dusts by water vapor enhanced microwave roasting was investigated, combined with the advantages of microwave selective heating and based on a thermodynamic analysis of zinc and lead halides. According to proposed reactions in the process, detailed experiments were systematically conducted to study the effect of roasting temperature, holding time, air flow, water vapor flow rates, and stirring speed on the efficiency of the removal of F and Cl. The results show that 97.26% of F and 64.23% of Cl could be separated when the condition of the roasting temperature of 650°C, stirring speed of 80 rpm, holding time at 60 min, air flow of 350 L/h and water vapor flow rate of 8 mL/min was optimized.

Jan 1, 2016

By Alex Del Castillo

The mineral processing industry has followed the development of database control systems, and various systems have been installed in existing and new plants. The goal is to improve product quality, raise productivity and lower production costs. Improvements in different units for mineral .processing .have been applied. This has led to increasing information for the operators. To support the operators and for an easy overview of the process, a complete concept for an integrated process-control system is required. This paper describes the plant-wide [process control system for the Collahuasi copper project located in northern Chile. The total investment for the project was $1,700,000,000 and included a port area and two copper processing plants, an oxide plant with a cathode production of 50 tons per year and a sulfide plant with a concentrate production of 330 kilotons per year. The main characteristics of the plant-wide process control system include a 200- kilometer long redundant control network and a 24-kilometer long redundant serial network providing coverage for the entire plant. The plants are located around 4,700 meters above sea level, serial communication lids allow the integration of over 2,700 SCADA data units, and the system handles over 7,500 physical signals plus the SCADA data integration. The main equipment consists of 39 different sized controllers, 16 operator stations, 5 engineering stations, 2 information management systems and 4 X- terminals. The project management, control configuration, factory acceptance test, system integration test, training, commissioning and start-up were carried out in close cooperation with the customer. The result was completely satisfactory for the customer.

Jan 1, 1999

By B. Mishra

Several reactive metal purification processes using molten salts generate effluent from which significant quantities of metal can be recovered prior to discardinglrecycling the salt. A Salt-scrub [SS] process has been applied where the reactive metals are recovered as a metal-gallium alloy by calciothermic reduction of the metal compounds. The SS alloy compositions were produced by mixing, pressing and sintering the metal-powders. Measurement of metal recovery has been studied for cerium, silver, tin and lead. The process has been optimized for variables such as the metal quantity per kg of effluent salt, amount of excess calcium over stoichiometry, stirring rate and time and holding time at reduction temperature. Over ninety-seven percent metal recovery has been obtained under optimized conditions. The development of an alloy for efficient Salt Scrub processing reduces a major contaminated waste disposal problem as well as recovering the valuable reactive metal. Surrogate metals have been used in this work to study the behavior of plutonium.

Jan 1, 1994

By Vinod K. Sikka, René Cooper

"Cohoes, New York 12047 Intermetallics are an attractive class of advanced materials. The aluminide intermetallics offer advantages including: (1) lower density, (2) oxidation resistance, (3) carburization resistance, and (4) interesting mechanical properties because of their ordered crystal structure. Even though the attractive properties of the aluminides and other intermetallics have been known for nearly four decades, their practical applications have not been developed for two reasons: (1) the poor ductility (in some cases, both ambient and high temperatures) and (2) the lack of processability into meaningful components. Recent advances such as ductilization of Ni3Al by small additions of boron and the knowledge that environmental effects are the major cause of poor ductility in Fe3Al and FeAl systems have brought the intelmetallics into the forefront of research and their commercial applications. This paper has described a method for melting Ni3AI-based alloys that successfully utilize the exotherrn for the formation of NiAl from the elemental materials. The reaction-synthesis method has also been utilized for the production of NiAI and NiAI-based alloy powders from the elemental powders. The reaction-synthesized powders of NiAI and NiAI-based alloys were consolidated by hot extrusion and evaluated for tensile properties over a temperature range from room temperature to 1050ºC. The powder-processing conditions have been found to have more influence on the ductile-to-brittle transition temperature of NiAI than the powder-production method.IntroductionIntermetallics are an attractive class of advanced materials [1-11]. The alum in ide interrnetallics offer advantages including: (1) lower density, (2) oxidation resistance, (3) carburization resistance, and (4) interesting mechanical properties because of their ordered crystal structure. Even though the attractive properties of the aluminides and other interrnetallics have been known for nearly four decades, their practical applications have not been developed for two reasons: (I) the poor ductility (in some cases, both ambient and high temperatures) and (2) the lack of processability into meaningful components. Recent advances such as ductilization of Ni3Al by small additions of boron and the knowledge that environmental effects are the major cause of poor ductility in Fe3Al and FeAl systems have brought the intermetallics into the forefront of research and their commercial applications. The paper will briefly review the processing techniques being pursued for the commercial applications of Ni3Al-based intermetallics. The major emphasis of the paper will deal with synthesis of Ni3Al and NiAI intelmetallics."

Jan 1, 1994

By Sylwia Zymankowska-Kumon, Rafal Danko, Mariusz Holtzer, Artur Bobrowski, Michal Kubecki

"Moulding sands with furan resin constitute constantly growing part in technologies of producing castings from iron alloys. Due to the presence of harmful substances in resins such as furfuryl alcohol, phenol and formaldehyde, using those mould sands may be hazardous to the natural environment and workers. The general assessment of harmfulness of sands used for molds and cores encompasses 2 basic points: emission of hazardous substances during processes of preparing sands, pouring mold with liquid metals (high temperatures), cooling and shaking-out; possibility of washing out hazardous substances from used sands to the environment, during storage or economic use outside foundries. We present the results of research on the assessment of harmfulness of mould sands with furan resin in the scope of the above points. The research was conducted according to the original method prepared by the authors, which has been used for years in cooperation with various foundries (Poland, abroad).IntroductionSands are used by the foundry industry to create metalcasting moulds, where the individual sand grains are typically bound using bentonite clay and carbonaceous additives or resins. During the casting process, the moulds can be exposed to temperatures as high as 1500°C depending upon the metal being poured. The molten metal causes thermal decomposition of carbonaceous additives or resins, which results in the formation of potentially hazardous organics that are emitted to the atmosphere and condense in the moulding sand [1]. The moulding sands are reclaimed within the foundry, but part of them are eventually discarded in landfills, because it is not longer suitable to make metalcasting molds [2, 3]."

Jan 1, 2013

By Jorge Gibson, P. Chris Pistorius, Megha Jampani

"The main reason for the significant carbon intensity of integrated steelmaking (approximately 1.8 tons of CO2 per ton of steel) is the use of carbon-based reductants in blast furnace ironmaking. Several changes to blast furnace ironmaking have been proposed as ways to reduce carbon intensity and cost. A conceptually simple two-zone blast furnace mass and energy balance can be used to quantify the expected impact of such process changes on coke rate, carbon intensity, and productivity. Examples to be discussed include top gas recycling, combining lower blast temperatures with increased coal injection to produce a rich top gas, using prereduced feed, and tuyère injection of natural gas. The use of the operating window – which illustrates how allowable flame temperatures and top-gas temperatures constrain feasible oxygen enrichment levels – is illustrated. Increased use of natural gas would lower the carbon intensity of blast furnace ironmaking.IntroductionBecause of the significant carbon intensity of steelmaking (approximately 1.8 tons of CO2 emitted per ton of steel produced) and the high production rate of steel (more than 1.4 billion tonnes per annum), steelmaking is responsible for a large percentage, approximately 6.7%, of world anthropogenic CO2 emissions [1]. By far the largest input of the carbon into conventional steelmaking is as coke, which is essential to blast furnace ironmaking. A typical fuel rate for blast furnace ironmaking is 450 kg of fuel per tonne of hot metal (THM). (""Fuel"" includes coke and injectants which partially replace coke; pulverized coal and natural gas are typical injectants.) Assuming the fuels to contain 90% carbon on average, and since nearly all of this carbon exits the steel plant as CO2, a fuel rate of 450 kg is equivalent to a CO2 intensity of 1485 kg/THM – by far the largest part of the total CO2 intensity of steelmaking.Blast furnace ironmaking is expected to remain the main source of new iron units; this paper gives some estimates of the extents to which further reductions in carbon intensity from blast furnace ironmaking is possible. A recent European assessment suggested that blast furnace process intensification options such as increased pulverized-coal injection or natural gas injection would yield only modest energy savings [2]. However, if the focus is on CO2 emissions rather than on total energy use, there would be an advantage to using fuels – such as natural gas – which have lower carbon contents relative to energy content."

Jan 1, 2014

By R. M. Taylor

Lime addition to acid mine drainage (AMD) leads to precipitation, predominantly of metal hydroxides and calcium sulfate, and is the benchmark for remediation by precipitation. Geo2 Limited of Melbourne, Australia has developed and patented a novel alternative precipitation scheme based on the formation of mixed valency, M(I1)-M(III), hydroxide sulfate salts. When the composition of AMD is appropriate, the Green Precipitate Process provides a useful and more effective alternative to conventional liming. The characteristics and utility of the Green Precipitate Process are described in terms of the underlying chemistry, and a case study where the Green Precipitate process outperforms conventional liming. A mobile pilot pipe reactor rig which was built by Geo2 to demonstrate the process, and used successfully in both Australia and the United States, is described.

Jan 1, 1998

By Francois Barthelat, Sam Goroshin, David Frost, Alexander Cappozi, Atefeh Nabavi

"In this study, a novel chromium–chromium sulfide cermet was produced by self-propagating high-temperature synthesis (SHS). Conventional techniques for manufacturing metal sulfides are complex, environmentally harmful, and not suitable for producing complex-shape articles. To overcome these disadvantages, a new method for the preparation of the metal-sulfur precursor charge is proposed, which can be described as reactive casting. The first cermet samples produced with the SHS process were found to be very porous, brittle, and have low mechanical strength. The possible sources for the generation of porosity were identified and analyzed and the process for manufacturing the cermet was modified. By improving the manufacturing process, the porosity inside the produced cermets was reduced from 70% to 12%.IntroductionMetal sulfide composites are in high demand in the chemical, metallurgical, and electrical industries because of their valuable characteristics such as hardness, semi-conductivity, electroluminescence, infrared transparency and catalytic properties. Current manufacturing methods for metal sulfides usually involve one of two different principal methods, including a complex multistage wet chemical process involving the precipitation of the corresponding salts from an aqueous solution with hydrogen sulfide, or hot sintering of the respective elemental reactant powders in a resistive furnace in a high-pressure inert or hydrogen-sulfide atmosphere [1, 2]. These conventional methods for synthesizing ceramic metal composites are complex, extremely time and energy consuming, environmentally harmful, and rarely able to manufacture articles with complex shapes. Therefore, in order to overcome these disadvantages, self-propagating high-temperature synthesis (SHS) was considered as an alternative method that offers significant improvements over the traditional cermet manufacturing methods [3]. SHS, which is a relatively new and attractive method for producing a wide range of advanced materials, is based on the self-sustaining feature of the highly exothermic reactions of the reactants. The SHS process results in high product purity, since the high temperatures generatedin the reaction cause any impurities to volatilize [4, 5]. SHS has low energy consumption and doesn’t require an external energy source and complex equipment, and it is self-contained [1, 5]. Since combustion synthesis has low power requirements, it is one of the few methods of materials synthesis that is feasible in outer space. Also, the process has a low cost and is capable of directly synthesizing articles with the desired shape, size and structure [5, 6]. The chemical reactions associated with SHS are typically completed in a few seconds leading to the formation of the condensed product. The high reaction rates and relatively rapid cooling in SHS reactions can avoid undesirable grain growth in products which often occurs with the conventional sintering method [3, 5, 7]. The traditional method for sample preparation in the SHS technique is to compact the reactant mixture powders in a steel die by a press to a typical density of about 80% of the theoretical maximum value, before igniting the mixture [8]. This method requires a large compression force to increase the green density and to minimize any pores in the green compact. To overcome these disadvantages, a new method for the preparation of the precursor charge in metal-sulfur by SHS is proposed which can be described as melt casting of a reactive mixture, or reactive casting in short."

Jan 1, 2012

By Ivan Imris

The common problem of new and conventional technology of copper production is the copper losses in the slags, which may be divided into mechanical and physico-chemical losses. In the first group can be included particles of mechanically entrained or floated unsedimented matte particles which coexist with slag. On the other hand, the physico-chemical losses are caused by solubility of copper in the slag in the form of sulphide and oxide. The copper losses in the slags from different processes has been predicted by calculation from thermodynamic data and compared with those determined by microscopic examination and quantitative electron microprobe analysis. Depending on the forms of copper losses in the slag the reduction of copper losses in the slag or the slag cleaning process could be suggested.

Jan 1, 2003

By N. L. Piret

Primary and secondary copper smelting dusts are being generated in varying quantities with very dissimilar characteristics due to the different compositions of feed materials and the type of process utilized. After categorizing the multitude of dust types, the criteria for on-site and off-site recycling of smelter dust in terms of type and concentrations of the accompanying elements are established. Thereby, consideration is given to the important aspects of: ? optimization of copper recovery ? quality of copper product ? valorization of accompanying elements ? elimination and disposal of deleterious impurities ? minimization of impact on operation ? effects on operating costs ? environmental impact of dust treatment on overall process Existing commercial, emerging and proposed copper smelting dusts, pyrometallurgical as well as hydrometallurgical, treatment schemes are reviewed and evaluated technically, economically and environmentally in an attempt to streamline the vast number of proposed options. Thereby, the high selectivity achievable in hydrometallurgical dust processing due to it being complementary to the smelting process is expected to be given increased consideration.

Jan 1, 1995

By I. M. Richardson, M. Janssen, W. Geerstma, I. J. Bennett, V. A. Popovich

Avoiding wafer breakage is a big challenge in the photovoltaic silicon industry, limiting production yield and further price reduction. Special fracture strength tests suitable for thin silicon solar wafers and solar cells, to be used in combination with Weibull statistics, finiteelement (FE) modelling and digital image correlation have been developed in order to study the mechanical stability of solar wafers. The results show that removal of the saw damage significantly increases the strength of crystalline silicon wafers. Furthermore, it was found that silicon crystallinity and the location where the wafer is extracted from the cast Si ingot have a significant effect on the strength, namely samples taken from the bottom of the ingot are 30% stronger than those taken from the top. The study also showed that there is a decrease in fracture strength when an anti-reflective SiNx coating is applied, which is caused by high thermal stresses.

Jan 1, 2015

By Lenny Winkel

With the aim to develop a solar-driven process for the extraction of copper from sulfide concentrates research on the decomposition of copper sulfides under inert atmospheres has been initiated. Thermogravimetric measurements on chalcocite,(Cu2S) revealed that copper is formed already at 1823 K. Chalcopyrite (CuFeS2) also disintegrates at this temperature, although at a lower rate. Copper and iron have been identified in the solid residue. The results confirm the feasibility of copper extraction by direct decomposition of sulfides under atmospheric pressure. The decomposition under inert atmosphere prevents generation of SO2, it also alters the behavior of volatile impurities during decomposition of copper sulfide concentrates. Chemical equilibrium calculations for chalcopyrite contaminated with enargite (Cu3AsS4) have shown that the absence of an oxidic slag allows for a complete evaporation of arsenic and subsequent separation from intermediate sulfides. The need to better assess the potential of direct sulfide decomposition has prompted the development of an experimental setup for studying the decomposition reactions. The experiment has been devised such that data on the decomposition kinetics and on impurity removal can be obtained at temperatures up to 2500 K.

Jan 1, 2003

By Ronald Erdmann

Today the BOF filter dusts and sludges are mainly dumped due to their zinc contents. By typically ranging from 2 to 5 % they prevent the filter dusts and sludges from beeing recycled via the blast furnace route. Based on the different discharge kinetics of Iron and zinc during the main blowing period In a bottom stirred BOF a simple and efficient system for recovery allow zinc fractions has been developed. The obtained material Is suitable for recycling without nsc of shell formation In the blast furnace. Different subsequent development steps have been performed. By starling with a very simple lime dependent model the sludge from the BOF off gas cleaning system was collected in two different sludge channel systems. This model based an the fact that most of the scrap based zinc Is discharged from the melt within the first eight to ten minutes of the BOF process. To Improve the system a spectroscope zinc sensor was Installed at the hot section of the off gas cleaning system to get more reliable informations on the actual zinc concentation of the BOF dust. By use of the system up to 50 % of the BOF sludge can be recycled.

Jan 1, 1995

By Lloyd Robert Nelson

The historical progression in installed electric furnace smelting capacity of some 1650 calcium, chromium, manganese, nickel and silicon ferro-alloys furnaces is reviewed. Key increases in the inherent installed electrical capacity, often achieved through uprating furnaces, are identified. Possible factors facilitating such advances are explored, including: specific process engineering and pyrometallurgical enhancements (e.g., improved control over the consistency, size and chemical form of raw materials, extents of preheating and pre-reduction delivered into the furnace; and patterns of feed distribution); furnace electrical configuration (AC or DC; immersed, submerged-, shielded- or open-arc); form of electrode (graphite, self-baking or composite); furnace configuration (circular or rectangular; closed or open and 1-, 3- or 6- electrodes); better engineering and equipment designs (e.g., high-intensity cooling) and state of furnace electrical and metallurgical control systems. A view is presented on the prevailing state of evolution of the Mega-scale in ferro-alloy smelting and opportunities for still further improvements.

Jan 1, 2014

By Wenzhou Yu, Cong Zhang, Wenhui Ma, Gang Wang, Kuixian Wei

"A novel technique was successfully developed for nickel further purification by vacuum directional solidification. The removal effect of impurities in nickel was studied based on theoretical analysis and experiments. High removal efficiency of impurities in nickel can be realized according to theoretical analysis. The experimental results show that the vacuum directional solidification treatment could increase the nickel purity from 99.96% to 99.996%. Since vacuum directional solidification could effectively remove the impurities from nickel with low contamination and low cost, it is a potential route to obtain high-purity nickel for commercial application.IntroductionNickel is widely used in metallurgy, machinery, petroleum industry, chemical industry, construction industry, light industry, and other industries for its ductility, medium hardness, ferromagnetism and high chemical activity. Nickel-based alloy is an important material for the key parts of aircraft, tanks, submarines, radars, nuclear reactors and aerospace fields [1-5]. Generally, nickel contains Si, P, S, Fe, Cu, Zn, As, Cd, Sn, Sb, Pb, Bi, Al, Mn, Mg and other impurity elements, which may hinder the commercial application of nickel. Therefore, it is necessary to refine the crude nickel for the high purity nickel."

Jan 1, 2014

A modified Cuprex Metal Extraction Process (CMEP) leach process was used to extract Cu. Ni and Co from a complex sulphide concentrate. The standard leach was modified to a two-stage countercurrent leach which provided emf control of the copper SX feed and minimized iron dissolution. A flowsheet was developed to recover the base metals and silver from the leach solution and gold and platinum group metals from the leach residue which was predominantly elemental sulphur. Techniques required to maintain an iron balance in the system including pressure oxidation and solvent extraction are described.

Jan 1, 1996

By Xiang-yang Zhou

Keywords: Low-Grade Dolomite, Low CaO Content, High Specific Surface Area, MgO. A low energy consumption preparation technology of magnesium oxide with low calcium oxide content and high specific surface area from low-grade dolomite has been investigated. The optimum technical conditions for the preparation of magnesium oxide are the followings: dolomite is partially calcined at 750-800° for 2 h; the optimum solid-liquid ratio range in calcined dolomite slurry is 20-30 g?l?1; carbonation temperature, carbon dioxide pressure and end point pH value of carbonation are less than 40°, 0.4-0.6 MPa and 7 respectively during carbonation process; decomposition temperature of Mg(HCO3)2 solution is near 100°; calcination temperature of the precursor (i.e. precipitated basic magnesium carbonate) is less than 850°. More than 90% of magnesium can be extracted by the technology. The MgO product (CaO < 0.38%) with a specific surface area of near 50 m2?g?1 also can be obtained by the technology.

Jan 1, 2005

By Asmo Vartiainen

Background of Direct-to-Blister Flash Smelting is discussed; especially slag chemistry relating to copper solubility, slag fluidity and impurity behavior. In December, 2000, Mini-pilot Flash Smelting test runs were carried out at Outokumpu Research Oy to produce blister copper from Chilean concentrate and white metal and from a mixture of them. Tested slag types were iron silicate slag, ferrous calcium silicate slag and calcium ferrite slag with different slag compositions and different concentrate/white metal ratios. The test runs were successful. The fluxing effect of copper oxide was clearly demonstrated and ferrous calcium silicate slags remained fluid on a very wide liquidus range. The distribution of arsenic between ferrous calcium silicate slag and blister copper is much higher than between iron silicate slag and blister copper. This successful test run with the new slag type offer new possibilities in Direct-to-Blister process design.

Jan 1, 2003

By Y. Pokhvisnev, S. Vandariev, A. Yatshenko-Juk, V. Valavin, V. Romenets

The technology of the liquid-phase reduction process known as Romelt was developed in the Moscow Institute of Steel and Alloys in 1979. The pilot plant was constructed at the Novolipetsky Steel Works (Russia) in 1984. Investigations into processing zinc-containing blast oxygen furnace dust and slag from the Lead and Zinc Works at the pilot Romelt plant proved the perspective of using this technology for processing zinc and lead-containing materials. In this article, the description of Romelt technology, basic technological information of trials at the Romelt plant using zinc-containing materials, compositions of charging materials, metal, slag, gas and dust are presented. The influence of flue gas composition on the composition of zinccontaining dust is shown.

Jan 1, 2000