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By Stanko Nikolic

The Top Submerged Lance (TSL) technology, developed in the 1970s, is now widely used for the processing of a range of materials. TSL technology for continuous converting was first patented in the 1990s. The process is based on the use of calcium ferrite slag. Although this slag system had been applied elsewhere the phase equilibria had not been thoroughly investigated. This lead to a collaboration between the Process Technology group of Mount Isa Mines, now part of Glencore, and the Pyrometallurgy Innovation Centre (PYROSEARCH) at The University of Queensland. Through multiple research programs this complex system was successfully investigated. The results were then implemented within thermodynamic modelling tools. This combined new knowledge was then applied to the design and industrial implementation of the TSL continuous converting technology, ISACONVERT™. This paper describes the key findings of the research and how this was applied to the industrial implementation of the technology.

By J. Van Boven

The Hoboken plant has continued the program, started in 1973, for monitoring the impact of processes on the environment. Progressive improve¬ments including new installations and equipment have been commissioned resulting in reduced emissions of lead in air. The Hoboken Smelter now fully complies with regulation and observes a yearly mean value of less than 2 micrograms Pb per cubic meter of air in the vicinity of the plant. In addition a new central water-treatment installation permits the discharge of waste water to the River Schelde in accordance with present day regulations. Mention is made of methods used to measure the emissions and immissions at the plant. Results of modifications and new installations recently commissioned are discussed.

Jan 1, 1983

By Valery M. Paretsky

The effect of the degree of nickel oxide reduction and the reaction gas composition on the furnace productivity has been estimated by computations and the established relationship is in good agreement with the practical data obtained in the process of electric smelting at the Severonickel smelter. An increase in the reduction degree within a range of =0.65 - 0.9 results in an increase in the furnace productivity by 19% to 37% and in a decrease in the unit electric power requirement by 16% to 27% depending on the reaction gas composition. The agreement between the computed and practical data has confirmed that the decisive factor for the process of treatment of reduced nickel oxide in an electric-arc furnace under the given conditions is the specific heat absorption, which is dependent on the nickel oxide reduction degree and the reaction gas composition.

Jan 1, 2005

By T. Maruyama

Tamano Smelter of Hibi Kyodo Smelting Co., Ltd. has been operating with one Flash Furnace (FSFE) and three Peirce-Smith Converters since its start-up in 1972. Anode production capacity has increased from 101,000 to 263,000 t/y by the several expansion programs, while converter capacity has increased and stable operation has been established by several improvements as listed below. - Expanding the furnace body (length) - Development of two kinds of automatic scrap charging system for each converter. (Increasing the in-stack time and better control of the melt temperature) - Oxygen enrichment at slag blow and copper blow - Increasing the blowing rate This paper reports the details of these improvements.

Jan 1, 1998

By D. McConchie

Management of caustic red mud wastes at the QAL bauxite refinery uses an innovative approach . involving neutralising the red mud with seawater; solids settle in a Red Mud Dam and residual water (pH = 8.6) is discharged to a tidal inlet. A survey of 18 trace elements in sediment, water, mangroves and molluscs, and an ecological survey of benthic fauna in the inlet, and at near-pristine control sites, revealed no significant trends that were linked to the discharge, except for the concentration of Al which was slightly elevated within 100m of the outfall. Trace element concentrations in water samples were close to, or below, world average seawater values and oysters collected near the outfall were acceptable for human consumption. The impact of discharges is minimised by a high tidal range, >60% flushing of the inlet in each tidal cycle, and the very high trace element binding capacity of sediment in the dam (> 100meq/ 100g dry mud).

Jan 1, 1996

By Yu Hu, Gabriella Tranell, Song Zhang, Eivind Johannes Øvrelid

"In the present research, recycling feedstock of silicon for Photovoltic (PV) application is investigated. Whether these recycling feedstocks are reliable in the future use is discussed in this work to assess the properties of the crystal silicon ingot, which is commercially pulled from top-cuts of casted multicrystalline ingot via one kind of Czochralski method - FerroTech. Dopant is the acceptor type Boron (B) and growth direction was <100>. Crystal diameter and the length were 190mm and about 1700mm, which were controlled by the temperature and the pulling speed, then cut to 156mm * 156mm wafers with 2000um and 200um thickness. Resistivity measurements of these wafers by Four Point Probe (FPP) are in good agreement to the calibrated profile after Rapid Thermal Process (RTP). In this work, the Minority Carrier Lifetime MCI, shown by Carrier Density Image (CDI) and Quasi Steady State Photo Conductance (QSSPC), gives the mapping results on the cross section and the relationship to the injection level, increases in an arrange from 40us to 90us along the ingot height, which is abnormal distribution compared to the standard ingot. Then Oxygen and other metal impurities distributions, measured by Flourier Transform Infra - Red (FTIR) respectively, account for the novel phenomenon of the continuously increased MCI. Various types of heat treatments were performed on these wafers (different ingot and different positions) in N 2 and 0 2 mixture atmosphere. Before and after heat treatment, micro-defects were revealed by copper decoration and etching work. Solar cells are fabricated by Energy Research Center of the Netherlands from the experimental ingot, and processed under an industrial standard line. Compared to results of the reference mono-crystalline and multi-crystalline silicon solar cells, the performances of experimental ones show excellent efficiency values up to 18.5%, and Jsc values up to 37mA/cm2.IntroductionThe PV industry has gone through rapid development, with a high growth rate resulting in an increasing demand for silicon feedstock. In addition, costs in production need to be reduced such that solar energy can compete other conventional and renewable energy. Searching low cost, reliable and efficient feedstock is one promoting way to improve and enhance the competitiveness of the PVindustry.More and more researchers start searching new raw materials for PV application [1]-[4]. The key to make full use of low cost raw materials is to control the distribution and effect of impurities, such as Carbon, Nitrogen, and other metal contamination [5]."

Jan 1, 2013

By Roberto Parra

The classic criteria of the preparation of the charge for the smelting of copper concentrates in at flash furnace considers the mass and energy balance from the chemical and mineralogy composition of the concentrates. The operation parameters fixed with this method don&apos;t assure the stability of the operation and the critical problems of the slag quality and dust formation occurs very often. This paper presents the results of a laboratory test that allows the prediction of the behavior of concentrates blends in the view of the minimization of the dust formation and the magnetite control in the slag. The combustion of different copper concentrates and blends were done in a drop tube furnace The results show that the magnetite and dust formation don&apos;t have a linear behavior with the weight proportion of the blend and some optimal blends of 2 or 3 types of concentrates can be identified. From the reasonable hypothesis that the qualitative behavior of blends in the drop tube represents the real behavior in the burner, the preparation of the charge with this approach could help to solve those operational problems.

Jan 1, 2003

By Junji Shibata

Waste solution from the Ni non-electric plating process contains 4.0 kg/m3 Ni, 0.1 kglm3 Fe, 0.0 I kg/m3 Zn, 48 kg/m3 S042-, 98 kg/m3 HP032-and 31 kg/m3 laetic acid as a typical composition. Solvent extraction, cementation, ion exchange resin and precipitation methods are possible to use for the treatment of this kind of solution. In this study, solvent extraction of Ni was investigated using two kinds of extractants to clarify the relation between extraction percent and pH for various extractant mixtures. As Ni ion has an octahedral structure with ligands, the synergistic effect for Ni extraction is considered to take place in solvent extraction using two types of extractants. The investigation of the synergistic effect for Ni extraction was carried out in case of various extractant systems.

Jan 1, 2003

By Shenghui Guo, Ying Lei, Wei Li, Jinhui Peng, Libo Zhang, Yu Li

"In this work, the Panzhihua low grade ilmenite and graphite were milled for 1, 2, 4 and 8 h firstly, then the temperature rising behavior of milled sample in microwave field were studied. The average heating rate of samples milled for 1, 2, 4, 8 h were 1.86, 4.08, 2.82, and 2.32 K/s; Before optimize the microwave reduction process, several experiments were conducted in order to confirm the parameters range. After milled for 4 or 8 h and reduced above 930 oC, the Fe metallization are higher than 90%; Then the optimization was investigated by using response surface methodology (RSM), the significance of predict model and each terms were analyzed, and the optimization parameters were given as: milling time is 4 h; reduction temperature is 1001 or 1070oC; the holding time is 37.5 or 26.9 min. Under these conditions, the Fe metallization given by predict model is 91 or 92 %.IntroductionThere is about 9.66 billion tons of Vanadic Titan-magnetite deposits in Panzhihua, China. In this reserve, there is about 8.73×108 t of TiO2, accounting for 90.54% of the Chinese reserves, and 35.17% of the international reserves and ranking first in the world. [1] Titanium mineral deposits are classified into Rock type and Placer type. Rock type is the igneous mineral, which have high content of FeO (Relative to Fe2O3) and gangue. The Panzhihua ilmenite is a typical rock type ilmenite ore. The higher contents of MgO, CaO, SiO2 and the complex mineralogy are making its direct reduction progressively more difficult."

Jan 1, 2011

By Ali Nadir Khan

Depleting copper resources and advancing technologies have challenged industries to develop more viable, adaptable and cost efficient processes using also secondary raw materials in copper production. This study is targeting to that goal by dynamic modelling of flow and heat transfer coupled with chemical kinetics in an industrial scale flash smelting furnace settler using commercial CFD software ANSYS Fluent. First, different physical phenomena occurring inside the settler, for example, settling and separation of the matte/slag phases, and heat transfer between slag/matte phases and settler walls are studied. Secondly, reaction kinetics between matte and slag, and between slag/matte and settler walls, and impurity element distribution will be studied. This would also include phase changes phenomena due to these reactions and the flow of the reaction gases inside the settler. Settling of polydispersed droplets, their coagulation, breakage, and WEEE particle behavior are further targets of the modelling work.

By Raymond E. Healy

Mercurian e1ectrum (Au-Ag-Hg alloy) is the principal Au-bearing phase in the massive sulphide ores at Trout Lake, Manitoba. The average composition of this phase (in wt %) is 49.2 % Ag. 38.7 % Au and 11.0 % Hg, with ranges of 17.34 to 76.47 % Ag, 1.62 to 79.86 % Au and 1.29 to 30.87 % Hg. Compositional variation reflects solid solution in the a-phase of the Ag-Au-Hg system. Backscatter electron imagery reveals systematic zoning and suggests a general crystallization sequence from metamorphic pore fluids of progressively Ag-rich compositions. Investigation of the occurrence of gold in mill products demonstrates that mercurian electrum accounts for over 90 % of the Au in Trout Lake ore. I Invisible" gold in pyrite (x = 0.72 ppm Au) and arsenopyrite (x 30.2 ppm Au) is confirmed by SIMS analyses, and accounts for 7-10 % of the Au in the ore, and 35 % of the Au lost to the tailings. The remaining 65 % of the Au lost to the tailings consists principally of mercurian electrum locked with pyrite. No significant losses of mercurian electrum in the size range amenable to flotation and/or regrinding is indicated.

Jan 1, 1989

By Yuri Gelfgat

"This paper presents some results of the investigation of the steady magnetic field influence on hydrodynamics and heat/mass transfer in processes of semiconductor single crystal growth (Si, Ge, InSn). The investigation employed mathematical and physical simulation techniques of relevant processes and full-scale experiments on growth facilities. A number of additional MHD phenomena have been found generated in the melt due to the rearrangement of flow pattern, the formation of specific convective cells, and the origin of MHD boundary and shift layer.IntroductionMagnetohydrodynamic (MHD) means of creating forces by contact-free methods in liquid conducting media have been widely used in the production of volume semiconducting single crystals. The goal of this method is to control convective transfer processes in the melt volume and on the crystallization front [1-3]. This is due to the sufficiently high conductivity of semiconductor melts (s = 104 /106 O1m-1 ) and an obvious relationship between the hydrodynamics in the melt and at interfaces and the conditions of formation of single crystals and their quality [ 1].All types of MHD effects rest upon the generation of volume electromagnetic forces in the melt by various means as well as on the possibility to direct them arbitrary in space and to adjust easily their absolute values. Fig. l presents different means how to implement MHD phenomena during single crystal growth. It should be emphasized that in all the modifications given in Fig. l additional energy introduced into the melt cannot influence directly the crystallization process since it is incomparable to the energy of molecular forces. Both the influence and efficiency of MHD means are determined solely by the change of motion, heat and mass transfer characteristics."

Jan 1, 1998

By Judy Che, Steven Ceccio, Gretar Tryggvason

"A detailed understanding of drop deformation and solidification is essential for quantitative predictions of geometry and properties of parts made by ballistic particle manufacturing processes. Axisymmetric results of towers built by the deposition of multiple drops are presented. In these computations, fluid flow, heat transfer, and phase change are fully coupled throughout the drop deformation and solidification process. The solution method is based on a single set of conservation equations written for all phases simultaneously. The phase boundaries are treated as imbedded interfaces by adding the appropriate source terms to the conservation equations. A parameter study demonstrates the effect of Weber number, Peclet number, and drop deposition frequency on the final shape of the structure. Numerical results show that most successful method of building uniform towers is when two conditions are met. First, each drop solidifies at the same time in the deformation cycle. Second, the cooling rate is slow enough to allow for good adhesion between drops. The ability to predict the final shape of deposited drops will greatly reduce the amount of experimentation necessary to select the desired set parameters for any artifact.IntroductionMaterial deposition techniques based on layering small molten metal drops holds the promise to build small, coherent three-dimensional structures. In this process, numerous 20-100 µm diameter drops are deposited onto a substrate with a low impact velocity (on the order of 5 mis). Both the momentum and trajectory of each drop are controlled precisely to build up complex parts. This material layering technique differs from processes such as spray forming and splat quenching which involve high impact velocities (on the order of 100 mis) and high frequency deposition with little control over individual drop placement. This process of layering small drops can produce parts with near net shape accuracy, while spray forming produces slabs of material which must then be worked to make a usable part. The ability to computationally predict final drop shape and cooling rate has the advantage of allowing the user to select parameters to produce parts with desired shape and mechanical properties. However, the development of such predictive methods requires a thorough understanding of both drop deformation and solidification"

Jan 1, 1999

By Peng Fan

Liquid phase tends to migrate from an aggregate of solid particles immersed in a liquid phase into another aggregate composed of the same solid particles and liquid but with smaller particle sizes and/or lower volume fraction of the liquid phase. This type of liquid migration in a two phase system can be attributed to the driving force for the system to decrease its total interfacial energy. With liquid migration pressure as a convenient measure for the total interfacial energy of a solid-liquid two-phase system, liquid migration can be attributed to the existence of liquid migration pressure gradient in the two-phase system. The kinetics of liquid migration is of great practical importance for many industrial processes, one of which is the liquid phase sintering of functionally graded WC-Co composite materials. During liquid phase sintering, WC-Co composite forms a typical solid-liquid two-phase system where solid particles of WC are immersed in liquid Co. For a sample composed of two layers of WC-Co with the same Co content but different WC particle size, Co gradient will be formed during liquid phase sintering; while for a sample composed of two layers of WC-Co with the same WC particle size but different Co content, the Co gradient will be eliminated during liquid phase sintering. The formation and elimination of Co gradient are controlled by the liquid migration pressure gradient. This paper describes a numerical simulation of the kinetic process of the formation and elimination of cobalt gradient.

Jan 1, 2006

By Yukihito Sasaki

Sumitomo Metal Mining Co. Ltd. planned an expansion program for the Toyo smelter and refinery in order to increase the production capacity of electrolytic copper to 450,000 tpy in 2007. Regarding the flash smelting furnace, a drastic increase in the average concentrate smelting capacity from 2,300 tpd to 3,950 tpd was required to achieve the plan. It was necessary to examine the performance of the Sumitomo concentrate burner when the feed rate was considerably increased. The authors developed a mathematical model to describe the combustion phenomena in the Toyo flash smelting furnace. This model was developed incorporating the fluid flow, heat and mass transfer, and chemical reactions of the copper concentrate and ancillary fuel. The copper concentrate was considered to mainly comprise chalcopyrite (CuFeS2). The reaction of CuFeS2 was assumed to consist of two steps, namely, the decomposition of CuFeS2 and the oxidation of the resulting pyrrhotite (FeS) and sulfur (S). The combustion phenomena in the furnace at the increased feed rate were predicted using this model. It was found that the Sumitomo burner was capable of enhancing the smelting capacity. This is attributed to the wide dispersion of the concentrate particles caused by an increase in the particle mass and a long residence time in the reaction shaft; this is due to the low temperature of the reaction air. However nonuniformity of the reaction in the reaction shaft was enhanced with the increased feed rate. In order to improve the nonuniformity of the reaction, an increase in oil-burner oxygen and an enlargement of the diameter of the dispersing cone were useful. By combining the expertise of the Toyo smelter staff and the calculation results, the concentrate smelting capacity of the Toyo smelter has been stably increased to 3,600 tpd thus far, and further improvements of the smelting performance are still being carried out.

Jan 1, 2006

By De-qing Zhu, Jian Pan, Tie-jun Chun, Dong Chen, Yu Cui

"A study of processing pyrite cinder and metallurgical slag using “one step” technology in strand grate - rotary kiln is presented, which aims to efficiently recover the valuable metals of iron, lead, zinc and copper. The effect of chloridizing roasting parameters including roasting time and temperature on the removal rates of nonferrous metals was investigated. It is shown that copper and zinc are difficult to remove and lead is removed more easily. The preheated pellets were reduced in a rotary kiln, where zinc and lead can be removed easily and high iron grade and good metallurgical performance prereduced pellets can be obtained. Furthermore, the chlorination and the reduction mechanisms of copper, lead and zinc are discussed. It is revealed that the phases of copper, lead and zinc in slag are complex and ferrite and silicate of metals are difficult to remove.IntroductionAs two kinds of significant secondary resources, metallurgical slag and pyrite cinder contain not only abundant iron but also considerable copper, lead, zinc and so on. Several tens of millions of tons of metallurgical slag and pyrite cinder are discharged in nonferrous metal and chemical industries annually in China [1, 2]. In addition, the accumulated waste slag in storage is more than one hundred million tons, which not only occupies much land but also pollutes the environment [3]. However, because the metallurgical slag and pyrite cinder are treated by high temperature processing, the properties are distinctly different from the properties of natural ores, and iron is in close association with copper, lead and zinc. So, metallurgical slag and pyrite cinder are difficult to efficiently utilize and only a small amount is used as additives in cement, paving, brickmaking and auxiliary additives [4-7]."

Jan 1, 2011

By Riyad N. Ahmad-Bitar, Shadia J. Lkhmayies

"CdSi-xTex thin films were prepared by first producing CdS:In thin films by the spray pyrolysis (SP) technique and then annealing the films in the presence of Te vapor in nitrogen atmosphere. X-Ray diffraction (XRD) measurements showed that the films are polycrystalline with the wurtzite structure. Transmittance measurements were recorded at room temperature in the wavelength range 400-900 nm and used to deduce the absorbance. The first derivative of the absorbance was calculated and used to find the values of the bandgap energy, where more than one bandgap was obtained for each film. These results show that the films are inhomogeneous or the composition differs with location. The photoluminescence (PL) was recorded at T = 60 K and a deconvolution peak fit was performed for each spectrum. The results of the PL spectra are consistent with those obtained from the first derivative and confirm the inhomogeneity of the films.IntroductionPolycrystalline thin film CdS/CdTe solar cells are promising candidates for low cost and high efficiency photovoltaic applications. The CdS/CdTe interface plays an active role and a detailed knowledge of its properties is crucial for thorough understanding of the device. High efficiency devices have been obtained in spite of the large lattice mismatch (9. 7%) between hexagonal CdS and cubic CdTe. Interdiffusion at the CdS/CdTe interface is considered to affect the performance of the devices [1]. The formation of a mixed crystal or a graded layer at the interface causes a reduction in the lattice mismatch at the CdS/CdTe junction [2] and then a reduction in the number of interfacial states and recombination centers, thus enhancing the solar cell performance [3, 4].The objective of this work is to investigate the transmittance, photoluminescence (PL) and structure of CdSi-xTex thin films prepared by annealing the spray-deposited CdS:In thin films in the presence of tellurium vapor. X-ray diffraction (XRD) was used for exploring the structure. Transmittance is used to deduce the absorbance where its first derivative was used to find the bandgap energy which varies with composition. The evolution of the PL spectra as functions of tellurium concentration was evident and it confirmed the inhomogeneities of the films."

Jan 1, 2011

By Di Yang

The influence of high density (104 -105 A/cm2) electric current pulses (70 us duration) and continuous DC (~103 A/cm2) on the flow stress and ductility in tension of a high carbon steel wire were determined at 204°, 427° and 649°C. Electropulsing (100 pulses per second) with an effective current density of 100-200 A/cm2 gave a 10% enhancement in the uniform elongation of the wire at 204°C, but had no effect at 427°C and 649°C. In contrast, continuous DC either had no significant effect on the ductility or gave a decrease. The electropulsing per se decreased the flow stress only slightly at 204° and 427°C, but gave a significant decrease at 649°C. Continuous DC increased the flow stress at all three temperatures. The present results along with those by others suggest that the enhanced ductility by electropulsing and the reduction in flow stress may be further increased by raising the effective current density through increases in either the pulsing frequency, maximum current density of each pulse or pulse duration. This could conceivably increase the reduction per pass during wire drawing or the number of passes between anneals.

Jan 1, 2001

By Hu Long

In this, the first systematic study of the oxidation of orpiment (As2S3) in sulfuric acid solution under oxygen pressure at temperatures above 170°C, the effects of retention time, temperature, particle size, oxygen partial pressure, the concentration of sulfuric acid and pulp density were evaluated. The effects of cupric and ferric ions on the oxidation rate of As(III) to As(V) were also examined. The products of oxidation are As(III), As(V), SO42- and elemental sulfur. At temperatures ranging from 170 to 230°C, most of the arsenic was found to be in the trivalent state, and oxidation to As(V) with oxygen was very slow. This was confirmed by attempting to oxidize a synthetic arsenious solution. However, the rate of oxidation of As(III) to As(V) is rapid in the presence of ferric ion. Elemental sulfur was found at all temperatures investigated, which can be further oxidized to sulfate at high temperature.

Jan 1, 1999

By Tiejun Chun, Marcus Emrich, Jian Pan, Deqing Zhu, Vinicius Mendes

"Joint projects of studies of hematite acid pellet have been implemented to develop technological solutions for using Vale hematite pellet feed in Chinese palletizing plant. Beneficial improvements on the pellets quality were achieved by adjusting the blends composition and using new technology of pre-treating the blended pellet feed with HPGR (High Pressure Grinding Roller) on rotary kiln pellet technology. The drop strength of green balls increased from 3.4 to 6.0 times from 0.5m height, at the same time, the bentonite dosage decreased from 1.5wt% to 0.7wt%. The compressive strength of roasted pellets reaches 2500 N/pellet. The reduction swelling index of roasted pellets is below 15%.IntroductionWith the fast development of steel industry in China, the production of pellets has been further expanded. Pellets are used as a high quality charge for blast furnace and the annual output is around 80Mt pellets [1]. According to the developmental trend, sinter will be replaced by pellets due to the larger environmental impact of sintering plants when compared to pelletizing plants. For example, the specific CO2 emission in sintering process is around 2.5 times higher than in pelletizing process. However, the steel industry of China has been confronted with a serious shortage of domestic pellet feed due to the low iron grade of Run-of-Mine ore despite of huge reserves of iron ores [2]. Therefore, more pellet feed, mainly hematite, has been imported to make pellets."

Jan 1, 2011