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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 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 Rivera Jose Antonio Ore

Top Submerged Lance (TSL) smelting technology is currently used in a wide range of applications in the non ferrous and waste product treatment industries. The use of TSL technology for tin concentrates smelting has been successfully applied at the Minsur Tin Smelter and Refinery at Pisco, Perú. The process is based on the air-cooled top entry submerged Sirosmelt lance, developed by Dr. John Floyd at the CSIRO division of Mineral and Process Engineering in the 1970?s. Advantages of the process include flexibility to operate the lance, main burner of the Sirosmelt furnace, with different levels of combustion stoichiometry which allows us to get from highly reducing to highly oxydising atmospheres in the smelting reactor according to the type of feed we are processing, ability to utilize cheap energy sources such as natural gas, low capital cost and an environmentally friendly operation. This presentation summarises the application of the Submerged Sirosmelt technology for smelting tin concentrates and a variety of tin containing materials like iron dross, copper dross, tin residues, low tin/antimony slags by applying recent metallurgical developments at the Minsur smelter. The impact of new feed conditions and level of impurities on reactor performance with features of process and operation control are described. As a result of these recent advances in tin smelting using TSL technology, the Minsur Tin Smelter and Refinery improved its overall tin recovery, substantially reduced tin inventories and became the second largest tin smelter in the world, currently producing more than 40,000 metric tones of refined tin per year.

Jan 1, 2006

By Nobuaki Sato

The electrical conductivity, k, of pure and sodium doped sulfur melts was measured with and without ultrasonic waves at temperatures ranging from 140 to 340° C by the two probe method using an ultra high resistance meter. The II: value of the pure sulfur melt with irradiation jumped at around 170°C by an order of 102 after which it monotonically increased from 10-5 to 10-4 (omega) 1cm-4 with an increase of the temperature. The addition of the sodium metal to the sulfur melt was found to cause a larger jumping in the II: value. The II: value increased with the increase of Na proportion in the melt. For a 10 mol% Na doped sulfur melt it was as high as max. ~30 (omega) 1cm-1 above 180°C under the irradiation of ultrasonics.

Jan 1, 2003

By Angus Hellawell

The application of the common tangent principle to free energy - composition surfaces is considered. It is shown that the construction requires that single phase surfaces on either side of a two phase volume must always exhibit the same sign of curvature - contrary to that shown in many published phase diagrams. In general, these curvatures will be such that the surfaces are mutually concave towards the more stable phase. A number of examples are discussed.

Jan 1, 1991

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 Jian-Xun Fu, Hong-Qiang Liu, Si-Yu Liu

The production of zinc-bearing solid dust is up to 4%~8% of total crude steel in steel plant, which is difficult to be recycled in traditional methods. To fully utilize the resources and reduce environmental pollutions, Chinese steel plants are using rotary hearth furnace (RHF) process to recycle solid dust. A consequential life-cycle inventory was carried out to assess the impact of dust recovery on greenhouse gas emissions based on the local production status. In the study system, the selected steel plant named which have 10.5 million tons of Crude steel productivity and 0.48 million tons solid dust come out meanwhile. To research, a RHF production line of 0.3 million tons directly reduced iron (DRI) a year was established to recycle the solid dust. The DRI will be obtained from RHF and sent to the blast furnace as raw materials to reduce the demand for iron ore and coke in steelmaking processes. By researching on the life-cycle inventory in the system, the steelmaking process with RHF was 2299.3kgCO2/ton steel. It’s a little higher while compared with the process without RHF, which data is 2297.0 kgCO2/ton steel. The small production of DRI make a small difference to reduce the carbon footprint of steelmaking process, the added carbon footprint of RHF process is more than BF and other steelmaking processes reduced. It is concluded that dust recovery has no contribution to the greenhouse gas emission reductions in the technic condition of Chinese steel plants currently.

Jan 1, 2016

By Lucas Nana Wiredu Damoah, Lifeng Zhang

"The use of electromagnetic field to remove suspended particles from metals such as aluminum by pushing to the boundary has been well studied. However, the potential of this method is yet to be exploited for the removal of inclusions from silicon. Considering the increasing amount of Top-cut SoG-Si scraps year upon year, there is the need to harness all the potentials of technologies to recycle this materials to ensure sustainability. This study investigates, and discusses new results on the effect of processing parameters such as composition, coil current, and frequency on the removal of inclusions from silicon under high frequency AC electromagnetic field.IntroductionThe solar cell silicon making industry requires pure and clean silicon in order to maximize the conversion potential of the solar cell material. The conversion efficiency of solar cells is limited by minority carrier recombination at dislocations and those intra-granular defects such as impurities, small clusters of atoms, or precipitates [1]. Recent global developments in the energy sector with a drive for the production of clean, reliable, and affordable energy have stirred a rapid growth in the production of photovoltaic (PV) cells.[2] Thus over the years, silicon based PV cells has seen a lot of growth as it has a PV market share of over 90 % [3] either as single-crystalline silicon, or multi-crystalline Si (MC-Si), or amorphous Si [4]. MC-Si produced by directional solidification of solar grade silicon melt dominates the silicon PV market. During the directional solidification process, SiC and Si3N4 particles within the melt are pushed by the solidification front to the top of the ingot which is the last to solidify. Therefore the top of the ingot is cut generating what is known as top-cut solar silicon scraps. The Si3N4 particles are mainly from the coating material at the inside surface of the silica crucible and from the air absorption during solidification process. The SiC particles mainly stem from the carbon reduction process of the primary production of silicon [5]. For sustainability the silicon in the top-cut silicon scraps must be recovered. Therefore methods for removing non-metallic particles, such as SiC and Si3N4, from the silicon are important in order to recycle the top-cut scraps to a useful feedstock for the silicon solar cells manufacturing."

Jan 1, 2012

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 N. J. Tannyan

Laboratory bath smelting tests were conducted to determine the feasibility of smelting nickel- copper concentrate directly to a low iron matte in one step. Concentrate, air/oxygen and a silica flux were fed to a matte-slag bath kept in MgO crucibles at I 300°C. Various oxygen enrichments and smelting rates were used to maintain 0.5 to 2 wt% iron in the product matte. The slag losses are comparable to those obtained under similar industrial conditions. Due to the highly oxidizing conditions required to produce mattes with low iron contents, it is not recommended to target iron contents below about 2% in the matte. The specific bath smelting rates were equal to or higher than those in various industrial bath smelting processes.

Jan 1, 2003

By C. W. Vierrether

Mineralogical analysis contributes directly to the selection of applicable beneficiation techniques for a given site. Tentative remediation methods for use on the Sharon Steel tailings in Midvale, Salt lake County, UT, were determined in part by mineralogical characterization. A systematic characterization scheme was employed to identify mineral species, mineral associations, and grain size. This paper presents the mineral content and distribution data collected for site characterization. This data was used to determine areas that were representative of the total tailings at the Sharon Steel site. Although this was the main focus of characterization, other useful information was obtained. The approximate location of "old jig tails" was identified and insight on possible arsenic, mobility through the pile was also obtained from the mineralogical study.

Jan 1, 1991

By A. N. Aposhian

The electronics industry generates tin/lead bearing by-products that can be recycled for their metal value. This paper will cover the processes used to recycle these tin/lead bearing byproducts from the plating, circuit-board fabrication and assembly industries. Though these processes are well known to the companies who do the recycling, few outside the industry including the generators of the by-products, understand the processes or needs of the industry. This paper will give a broad overview of these processes, and describe the services provided by this industry. The paper will also touch upon the future of the recycling industry, including the legislative and environmental push for the elimination of lead from electronics.

Jan 1, 2000

By Huaming Yang

Infrared materials are a special kind of material widely used in military, biological engineering and chemical industry. However, the problems associated with them such as unstable properties, high cost and a high thermal expansion coefficient seriously restrict the development and the wide application of the traditional infrared materials with the SiC or ZrSiO4 matrix. The ultrafine quartz powder is normally used to prepare the infrared materials by hot-pressing technology. The aim of the paper is to investigate the thermal expansivity, the effect of the SiO2 size and the addition of Al2O3 or Fe2O3 on the infrared emissivity of the quartz matrix of the infrared material (QMIM) in a 8-25um wavelength range. The results indicate that 89% of infrared emissivity and 0.4x 10-5/°C of thermal expansion coefficient of QMIM can be obtained. The affecting mechanism of A1203 and Fe2O3 on the infrared emissivity of QMIM were also discussed.

Jan 1, 2003

By A. V. Tarasov, V. M. Paretsky

"The design is based on the thermal processing of the wastes in· the intensively bubbled melt in the Vanyukov furnace at the relatively high temperatures (1350- 1450 °C), In this case: -the secondary wastes are not formed; - the especially toxic substances at the outlet from the furnace are absent. The technology was tested on a large scale (on semicommersial bases). Technical and economical basis show profitability of recovery complex for processing of hard garbage waste (HGW) using this technology: the period of capital, investments refunding for the, recovery, complex construction with process annual capacity of 240 thousands tons of wastes is 1,5-2,5 years,"

Jan 1, 2000

By Kouji Mimura, Tamas Kekesi, Yongfu Zhu, Masahito Uchikoshi, Minoru Isshiki

"The formation and anion exchange sorption of chloro complex ions can offer a great potential to be utilized for the separation and purification of metals in aqueous solutions. Available stability data were primarily used to estimate the predominance of chloro complex species, indicating the feasibility of such separations. Anion-exchange sorption functions, describing the equilibrium distribution of a number of important elements have been determined by the batch equilibrating method in the practical HC1 concentration range. Various oxidation states were stabilized by the addition of appropriate agents. Tendencies in oxidation, complex formation and anion exchange sorption were confirmed by spectrophotometric investigations. Based on the fundamental results, anion exchange processes have been developed for the purification of iron, cobalt, copper and zinc. The efficiency of separation was assessed and the procedure optimized by the analysis of experimental elution curves. Results have demonstrated that by properly controlling the oxidation states and HC1 concentrations, practically all the impurities can be eliminated. Computer programs have been developed to estimate complex formation and redox equilibria, to screen and correct analytical data, to determine distribution coefficients and to evaluate efficiencies of separation.IntroductionBase transition metals have long been used as the staple materials in various fields of industry. In general, there has been an increasing tendency in purity requirements but recent advances have created a rapidly increasing demand for ultra-high purity metals. To give a few examples, ultra high purity copper can be used as bonding wire and interconnection in integrated circuits, or as material for superconductor stabilizing, high-field magnets, beside its use in cryogenics and ultra high vacuum technology [1]. Iron holds promises as a constituent element in the ß-FeSi2 material to be applied in new opto-electronic devices [2] and it is currently used, together with chromium and manganese, in the production of special magneto-optical materials for digital recording. The use of ultra high purity manganese and chromium in semiconductor technology is evolving. Although not considered a transition metal, zinc is also treated here because of the major significance in compound ZnSe semiconductors [3], and the possibility to purify it by the anion exchange method."

Jan 1, 2000

By W. F. Whittaker

Systematic control of process parameters during electrorefined copper cathode production and final product inspection ensures high quality of produced "ORC brand copper. Since 1986, substantial increases in tankhouse productivity have been achieved by a number of technological and process control changes. This paper reviews the changes implemented to achieve higher productivity and cathode quality.

Jan 1, 1992

By Sung Wng Kim

The binary antimonide compounds with the skutterudite structure have a potential for thermoelectric applications because of the high carrier mobility, high thermoelectric power, and relatively low thermal conductivity due to the complex crystal structure. However, the room temperature thermal conductivity of these skutterudite materials is as high as about IOW/mK with an estimated 80-90% contribution from the lattice thermal conductivity. Because the lattice thermal conductivity of related ternary skutterudite compounds can be substantially reduced due to the additional phonon scattering, a study of thermoelectric properties of these compounds is of interest. The binary IrSb3, ternary Ir1.xRuxSb3 and Ir(MxSb1.x)3(M=Ge, Sn) compounds were prepared by hot pressing of pre-reacted powders. We have measured the electrical resistivity, thermoelectric power, and thermal conductivity, in a temperature range from room temperature to 973K. The binary IrSb3 compound is found to have P-type electrical properties exhibiting a good Seebeck coefficient (up to 225µV/K around 773K), electrical resistivity(5x10-5Ohm M around 933K), and relatively low thermal conductivity(6W/mK around 950K). The lattice thermal conductivity, K[2] was calculated from the Wiedemann-Franz relationship.

Jan 1, 2002

By Richard Hollis

The Mount Isa copper smelter was expanded in 1998 to a capacity of over 250000 t/y anode copper. This tonnage will be produced from a single stream consisting of an Isasmelt smelting furnace, and four Peirce-Smith converters - one of which was installed as part of the expansion project. During the course of the expansion project Mount Isa Mines Limited (MIM) signed an agreement with WMC Fertilizers Ltd (WMCF) to supply sulphur containing smelter gases over the fence to a new sulphuric acid plant to be built by WMCF. This will result in a further increase in copper production by reducing the time when smelting is curtailed by Air Quality Control restrictions. As well as the need to modify the primary gas system to connect to the acid plant, the hoods and crossover ducts and their support structures on the original three converters required replacement, and secondary ventilation was also needed to improve converter aisle hygiene. Each of these areas was addressed by the project. Preliminary ideas for carrying out the modifications were found to have a serious impact on converter aisle operations, and would have led to a production loss of over 50000 tonnes of copper. Following benchmarking in other copper smelters, a suitable construction plan was developed and carried out to minimise this loss. This paper describes the methodology and construction plan adopted.

Jan 1, 1999

By S. I. Sobol

The results of the study of the mechanism of a cathode process of cobalt electrolysis to explain disagreements in a form of kinetic equations of autoclave reduction of nickel and cobalt have been used.

Jan 1, 1993

By Andreas Ludwig, Abdellah Kharicha, Menghuai Wu

"In order to demonstrate how CFD can help scientists and engineers to better understand the fundamentals of engineering processes, a number of examples are shown and discussed. The paper will cover (i) special aspects of continuous casting of steel including turbulence, motion and entrapment of non-metallic inclusions, and impact of softreduction; (ii) multiple flow phenomena and multiscale aspects during casting of large ingots including flow induced columnar-toequiaxed transition and 3D formation of channel segregation; (iii) multiphase magneto hydrodynamics during electro-slag remelting; and (iv) melt flow and solidification of thin but large centrifugal castings.IntroductionSince the Bronze and the Iron Ages, material processing, and here especially metallurgy, has got a global importance for the economic well-being of the societies. It is thus understandable that metallurgy has changed from arts and crafts into an engineering specialty, where the knowledge of centuries has lead to an enormous commercial and technical efficiency. However, increasing competition and the necessitation of energy and CO2 reduced manufacturing methods requires the improvement of existing techniques and even the development of new, alternative production technologies. On the other hand, the opacity of liquid and solid materials and the involved high temperatures makes the experimental penetration of metallurgical processes and with that the attainment of detailed process knowledge quite difficult."

Jan 1, 2012