Search Documents

By Yuan Zeping

The distributions of impurities in the copper melt, the slag and the gas phase in copper flash smelting process were under study in the Guixi smelter, particularly during operating conditions of high oxygen enrichment with production of high grade matte. Several methods for the removal of impurities such as As, Sb and Bi in the copper smelting process were developed and implemented at the Guixi smelter. This paper described the effects of high oxygen enrichment, elevated matte grade, high temperature and high production rate on the distribution of impurities, methods adopted at the smelter for the removal of impurities, and the associated benefits in the utilization of these removal techniques which include the mathematical model for material blending, high thermal intensity operation at the flash furnace, extended converter blowing, and injection of slag modifiers consisting of Na2CO3 and CaO powder mixture to the converters and anode furnaces.

Jan 1, 1999

By A. Lakschevitz

The Amazon region offers a large potential for gold extraction but its peculiar characteristics such as heavy rains, lacking of roads and general infra-structure, nature of the ore deposits, etc.. do require special care in plant design. REMETÁLICA has developed a know-how is designing leaching plants which have been demonstrated to be profitable under those tropical weather conditions. The solutions adopted are related to general process route, leach liquor distribution and flow pattern, conditioning of solids and effluent treatment. These plants, now operating in South America countries, demonstrate the success for the technology developed. A tipical plant with 800 t/day ore processing capacity, may require an investment of US$ 1.200.000,00, arid have? a pay back period of a few months, depending on ore grade.

Jan 1, 1989

By S. K. Kawatra

"A typical steelmaking facility produced 50,000 tons per year of slag in their hot-metal desulfurization process. This slag had a sufficiently high iron content that it could be beneficiated and recycled in a blast furnace, provided that the slag could be agglomerated into pellets suitable for use as blast furnace feed. In this work, beneficiated slag was agglomerated using both a conventional bentonite binder, and a fly-ash-based binder (FBB) that was formulated by the investigators. The FBB consisted of a combination of highcarbon fly ash with calcium hydroxide activator, allowing the FBB to exhibit binding properties when moistened. It was determined that beneficiated slag agglomerated with FBB had superior compressive strengths compared to slag agglomerated with conventional bentonite binder. The FBB is therefore a satisfactory method of binding the agglomerated slag. Since the fly-ash component of the FBB is commonly discarded as waste, this approach also provides a means for utilizing high-carbon fly-ashes that currently have very little commercial value.IntroductionIn 2006 approximately 72.4 million short tons of fly-ash were produce in the United States [1]. The majority of fly-ash which was used that year was consumed concrete, structural fills, and cement. It is also used in road base, aggregate, and other applications. However, 55.2% of the fly-ash produced in 2006 was not utilized and ended up being sent to a landfill. Essentially all of the land filled fly-ash could be a suitable binder for pelletizing desulfurization slag and other steel plant waste oxide materials. Fly-ash based binders (FBB) have been shown in laboratory studies to be suitable for producing iron ore concentrate pellets of equivalent strengths as those bonded with bentonite [2,3,4]. The utilization of highcarbon fly-ash within the market is important for reducing the volume of currently unmarketable and land filled fly-ashes. FBB would be a much cheaper alternative to the current bentonite binder or organic binders used for iron ore concentrate and would help to reduce pellet costs. Currently, transportation more than doubles the final cost of bentonite since it is produced hundreds of miles from the pelletizing plants, while fly-ash is produced from power plants located nearby pellet plants and steel mills. FBB’s also show promise for use in other high volume applications such as foundry sand mold binders."

Jan 1, 2008

By Peter Brown

The present work involves the study of Chemical Vapor Deposition (CVD) of silicon carbide from the methyltrichlorosilane (MTS) - hydrogen system. A computer program, SOLGASMIX has been employed to calculate the equilibrium compositions of the gaseous and condensed phases in the MTS - H2 system. The results indicate the range of parameters such as temperature, pressure and species concentrations, required to deposit the single phase Sic under thermodynamic equilibrium conditions. A mathematical model for describing the transport phenomena and the rate of deposition of Sic onto a thin rod in a vertically-oriented hot-walled CVD reactor has been developed. Exper iments were conducted using the same operating conditions as those used in the model in order to validate the mathematical predictions. The predicted rates of deposition were found to be in good agreement with those obtained experimentally. The model can be used to study the effects of various operating parameters on the rate of Sic deposition on a fiber.

Jan 1, 1992

By F. Mucciardi

While flash smelting and converting are capturing a greater share of the market, injection through circular injectors will remain with us for the foreseeable future. The use of top lances for injection is a key feature in several processes (e.g. Mitsubishi, Ausmelt). Tuyeres, on the other hand, are incorporated into a number of processes (e.g. Noranda, Peirce-Smith). To date no lances or tuyeres are cooled by an external source. The reagent provides the bulk of the cooling. With limited cooling, it is normal to have substantial wear on the nozzles - especially in the case of lances. To overcome the issue of wear, a new patented injector (lance or tuyere) has been developed by Noranda and McGill University. This novel unit is based on heat pipe technology. It can operate for an extended period of time without wearing. Enhanced lance/tuyere life is achieved by operating the injector at a low enough temperature that promotes the formation of a thin frozen layer on the outer body of the unit. The vaporizing and condensing substance within the unit acts to cool' the high heat flux portions and dissipate the heat to areas of low heat flux outside the vessel. A fairly large number of tests have been conducted with a prototype unit. The tests have shown that the heat pipe lance is a viable unit. In this paper is detailed a test which illustrates how the lance functions when pure oxygen is injected into copper matte. In addition, the findings from a basic study of a heat pipe in high heat flux environments are also presented.

Jan 1, 1999

By G. Azimi

Calcium sulphate precipitation, mainly as gypsum, during neutralization of acidic hydrometallurgical process solutions can lead to excessive scaling problems. In this work, a self-consistent fundamental chemical model is presented based on the OLI software platform. The model employs the new Mixed Solvent Electrolyte (MSE) activity coefficient model of OLI. A thermodynamic database has been developed and calibrated on experimental data from metal sulphate solutions. The model predicts very well the solubility of calcium sulphate within a wide temperature range and can be used to assess the scaling potential of a particular process stream composition. The effect of temperature, acidity, and divalent metal concentration on the solubility of calcium sulphate in multi-component process streams is also simulated and discussed.

Jan 1, 2006

By A. V. Tarasov

The lack of technology for processing of sub-grade ore concentrates and intermediate products for extraction of Zn, Pb, Cu and precious metals at the metallurgical stage was a constraint for an increase in the production of these metals. The technology developed in the Gintsvetmet Institute is based on an improved electrothermal smelting process for treating calcined charge, ensuring thereby a reduction in power requirement and improving the environmental performance of the process. Electric smelting of sub-grade polymetallic concentrates produces lead bullion, to which the bulk of gold and silver reports, as well as well segregated matte and slag concentrating the bulk of zinc. Lead bullion and matte are commercial-grade products; zinc is recovered from high-grade (15% Zn) slag by slag fuming process. Reduced loss of precious metals in slag ensured by the given technology is attributed to the fact that the slag contacts with matte with low contents of gold, silver and lead, rather than with lead bullion. Limited amounts of off-gas typical of electrothermal processes ensure cost-effective operation of dust recovery devices and a reduction in emissions of harmful pollutants into the ambient air.

Jan 1, 2002

By Tao Li

The development of DP(Dual Phase) steels and TRIP(Transformation Induced Plasticity) steels has received much attention in recent years due to their high strength and simultaneous good ductility, which provides the potential for weight reduce and resource savings on certain components in automobile or other industries. So a controlled rolling process was simulated in the present study by thermomechanical simulator (Gleeble 1500) for producing DP steels on a kind of low carbon steel containing a small amount of Si and Cr. F+M dual phase microstructures have been obtained during continuous cooling processes of a wide cooling rate range from 10°C /s to 60°C /s. The grain size of the dual phase steel developed can be refined to less than 5 m through the mechanism of deformation induced ferrite (DIF) transformation. The ultrafine ferritic grains are equiaxed with high-angle boundary, and the martensite islands of an average size less than 5m disperse uniformly in the ferrite matrix. The ultrafine martensite islands not only inhibit the growth of ultrafine ferritic grains and improve the bonding of F/M interface, but also increase remarkably the strain hardening rate in the processing of the present Dual-Phase steel. As a result, the tensile strength of ultrafine grained Dual-Phase steel reaches higher than 1000 MPa. The result shows that an ultrafine grained Dual-Phase steel of low carbon and low alloy is promised to exhibit desired F+M microstructure by means of this new TMCP process.

Jan 1, 2006

By Daniel Kim, Justin McAllister, Shijie Wang

"At the Kennecott Utah Copper Refinery, impurities in the electrolyte are being precipitated in the circulation system and form a hard scale in the piping. This scale must be removed periodically for proper electrolyte flow. Distinct layers of differing composition form as the operating conditions of the tank house change. Scale samples from the inlet and outlet pipes were analyzed to discover the nature of the precipitates. Each sample was sectioned and examined under optical microscopy and SEM. The composition of the scale was analyzed using ICP, XRD, and SEM/EDX mapping. The rate of deposition was determined by measuring the amount deposited on new pipes after elapsed time intervals. In order to determine how to minimize the formation of the scale, the mechanism was studied and the results are presented in this paper.IntroductionIn copper electrorefining, impure copper anodes are refined into pure copper cathodes. The impurities from the anodes are either insoluble and report to the slimes or soluble and dissolve concentrating in the electrolyte. These impurities are controlled by bleeding electrolyte from the system. Over time, the impurities combine to precipitate a hard scale on the surfaces contacted by the electrolyte. The scale causes problems with tank house circulation systems. In order for the refinery to operate properly, the scale must be removed periodically from the walls of the pipes. The first step to control the buildup of scale on the pipes is to understand the composition and the phases that are present in the scale."

Jan 1, 2012

By P. D. Navarro

The behavior and operability of LIX 1104SM extraction was studied at laboratory scale on the Solvent Extraction at Sb3+, from high concentration sulfuric acid. In order to evaluate the reactant batch tests were made at laboratory scale as well for extraction as for re-extraction of Sb3+. Experiences achieved were: extraction kinetics, temperature effects, selectivity tests and re-extraction selectivity. A extraction kinetics was found, reaching equilibrium in 2 min, high selectivity of Sb3+ extraction in front of Cue , existing As5+ co-extraction and Fe3+ At the re-extraction stage, equilibrium was reached in 3 min, getting high Sb3+ re-extraction efficiency with HCl concentrations within 6 and 8 M. A high selectivity was achieved on Sb3+ re-extraction in front of As+5, existing Fe+5 re-extraction.

Jan 1, 1999

By Jens Kristen Laursen

In 1999, Molymex S.A. de C.V. (Molymex), Mexico. (a company wholly owned by Molibdenos y Metales S.A. (Molymet), Chile) decided to install the Haldor Topsrae Wet gas Sulphuric Aicd (WSA) process for cleaning of the 4-5% SO2 off-gas from their molybdenum sulphide master in Cumpas, Mexico to produce sulphuric acid. The decision to install a WSA plant was based on the successful operation of a WSA plant at Molymet's molybdenum sulphide roaster in Santiago, Chile since 1993. This paper describes the process layout of the Cumpas plant, the operating experience of the Santiago plant, and the, differences in. process design between the two plants. It will furthermore summarise the applications of the WSA process for other roasting plants and smelters within the non-ferrous. metals industry producing metals such as copper, lead, and molybdenum.

Jan 1, 2002

By Shadia J. Ikhmayies

"Cadmium sulfide thin films were prepared on glass substrates by the spray pyrolysis technique at a substrate temperature of 490°C. Some of the films were etched by HC1 in distilled water, others were heat treated in nitrogen atmosphere, and another set of films was first etched by HC1 and then annealed. Room temperature impedance spectroscopy measurements on the films were performed using coplanar geometry in the dark and in room light in the frequency range 20 Hz to 1 MHz. The experimental data were represented by complex plane diagrams and showed one well-defined semicircle in the high frequency region. Hence the equivalent circuit that models the CdS: In thin films was found to be a single RC circuit, which indicates the bulk conduction through the grains. The influence of treatments on the electrical properties was investigated.IntroductionCadmium sulfide (CdS) is a brilliant II—VI semiconductor material with a direct band gap of 2.42 eV at room temperature. It has many outstanding physical and chemical properties, which have promising applications in multiple technical fields including photochemical catalysis, gas sensor, detectors for laser and infrared, solar cells, nonlinear optical materials, various luminescence devices, optoelectronic devices and so on [1]. There are different methods to prepare undoped and doped CdS films, such as rf sputtering [2] chemical bath deposition (CBD) [3], pulsed laser deposition (PLD) [4], and spray pyrolysis (SP) [5-11]. Of these methods, spray pyrolysis represents the less expensive option, and can produce large area high-quality low cost thin films [12]."

Jan 1, 2012

By W. G. Davenport

The paper "Copper Smelting to the Year 2000" was presented at the CIM Conference of Metallurgists in Sudbury, August 1979. That paper predicted, in part, that high matte grade, high oxygen smelting - particularly in flash furnaces - would dominate copper smelting until the beginning of the next millennium. The present paper re-evaluates that prediction and examines the changes that have occurred and will occur in copper extraction in the 1990's. Of particular interest is the question as to whether major competitors are on the horizon for flash smelting and Peirce-Smith converting. Recent results with direct-to-blister smelting, lance smelting and submerged-tuyere smelting are reviewed and their roles in future copper smelting are predicted. Requirements for H2SO4 plants which handle the off-gases from modern smelting/converting processes are also examined.

Jan 1, 1993

By H. Dijkman

The PAQUES Bio Systems' core technology, marketed under the name THIOPAQ®, consists of various high-rate biological processes for metal-sulfur-water systems, complemented with common solid/liquid and gas separation steps. Sulfur species are converted to sulfide, which is a valuable component as it can be used for metals reduction and precipitation. Selective recovery of valuable metals can be employed, leading to revenue from metal values. In this paper, biotechnological systems for the treatment of metal sulfate solutions and dilute SO, gases are described. These installations can be designed to either produce predominantly aqueous (NaHS) or gaseous (H2S) sulfide. The emphasis here is on hydrogen sulfide gas. The main case history discussed is the demonstration plant that ran on hydrogen gas at Kennecott Utah Copper. Three years of operating experience clearly show that sulfate reduction with hydrogen gas is a viable option. Furthermore, the selective recovery of copper from leach water with the hydrogen sulfide produced was shown to be very effective.

Jan 1, 1999

By I. Sofia Fernandez del Rio

This paper describes a process for the treatment of the dusts generated during the operation of blast and reverberatory furnaces in the lead smelter, to remove zinc, cadmium, arsenic and halides from the circuit. The process consists of a Pefloles' developed leaching/purification stage and a solvent extraction process developed by Lurgi. The plant capacity is 5,000 tonnes Zn/year. The feed to solvent extraction contains 8 g/1 Zn. Impurities such as copper, iron, arsenic and cadmium are removed by conventional cementation processes. The cadmium product is 99.99 % pure. The solvent extraction process consists of two extraction stages, one washing stage and two stripping stages. D2EHPA is used as the extraction agent and 25% ammonia as the neutralizer. The rich-zinc solution is sent to the electrolytic zinc plant for zinc recovery. The raffinate produced, which is a mixture of ammonium sulfate and chloride, is used for agricultural applications.

Jan 1, 2000

By James R. Myers

A source of clean gas containing sulfur dioxide and sufficient oxygen for conversion to sulfur trioxide is essential to the production of sulfuric acid. SO2 containing gases obtained from roasting sulfide ores are heavily contaminated with inorganic dust and volatile impurities. If not removed, these contaminants will reduce product acid quality, foul the catalyst beds and mist eliminators, and accelerate equipment corrosion. This paper reviews conventional gas cleaning systems for metallurgical acid plants, followed by a discussion of modern systems utilizing DynaWave Scrubber technology. This technology is based on a unique approach togas scrubbing that can concurrently accomplish several gas cleaning/processing tasks. Scrubbing liquid is injected into the gas stream to create a "Froth Zone". This is a region of extreme turbulence, with a very high rate of liquid surface renewal. It efficiently removes both particulate matter and gas contaminants, and is also a cost effective quenching device for gases as hot as 1250 o C.

Jan 1, 1992

By Aichun Zhao, Rui Wang, Yihong Li, Yanping Bao, Yafeng Ji, Jiansheng Liu, Xiao Hu, Qingxue Huang

The slag entrapment under different conditions of 80t blowing argon ladle furnace was investigated by physical simulation. The water was used to simulate liquid steel and liquid paraffin was for slag. The processing of slag entrapment under different blowing structures was analyzed and the critical velocity and critical droplets diameter of describing it was obtained. Based on the experiments, the relationship between the interface flow velocity and the critical blowing rate CBR was deduced. In the real process, it is suggested that the bottom blowing rate is from 40 L/min to 180L/min when the interface tension is 0.12~1.2 N/m during the soft argon blowing.

Jan 1, 2016

By Jin Liu

The mechanism and rate of carbon reduction of each of the phases that are formed in the flash flame, i.e. sulfide (matte) and oxysulfide, was investigated. Graphite-slag reduction was conducted for comparison purposes. The objective of these tests was to measure the rate of solid graphite reduction of respectively matte, oxysulfide, slag, and matte+slag mixture at different temperatures. More in particular, these tests were expected to permit understanding and explaining the reduction mechanism of each material by comparing the respective reaction rates, product reaction gas compositions and CO/CO2 ratios, reduced material assays, activation energies, and other relevant parameters. Direct visual inspection of the test crucibles would provide additional information.

Jan 1, 2006

By Jin-Chun Kim

Nanosized W based powders (W, WC, WC-Co) were produced by chemical vapor condensation (CVC) process. Two different solid W(CO)6 and Co2(CO)8 metal-organic materials were used as precursors. CVC experiment was conducted in the temperature range of 400-1100. As-CVC WC1-x powder which had non-stoichiometric composition was carburized by using of the CH4-H2 mixed gas in temperature range of 750-850. The CVC W and WC1-x powders showed loosely agglomeration structure, and the Co powder had intricate long stand structure because of intrinsic magnetic properties of Co phase. Carbon content of the CVC powders controlled by gas-phase carburization was well matched with theoretical WC stoichiometry (6.13wt%).

Jan 1, 2006

By Gus Van Weert

This paper describes the results of autoclave testwork where ferric nitrate was hydrolysed in the presence of certain cations and anions and the resulting hematite analyzed for foreign constituents. For the cations Zn++, Ni++, Cu++, and AI+++, selectivity factors of over 107 were found. Magnesium gave 3.106. These factors are calculated as Me/Fe in solution over Me/Fe in the hematite; Me representing the metal in ion added. As-a result of the testwork at Delft University of Technology, BUDELCO (the Netherlands electrolytic zinc producer) ran a series of ferric nitrate hydrolysis tests in the presence of 10 additional trace elements. Impurity levels were prejudiced on Me2 EPHA extraction of iron from their zinc circuit, followed by HNO3 stripping. Good selectivity against base metals was confirmed, but trace elements forming anions (As. Sb) and sulphate were incorporated in the hematite. These BUDELCO results are also presented.

Jan 1, 1995