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By Philip Arthur

The ISASMELT process is making a significant contribution to the global metals industry. ISASMELT furnaces are now operating successfully in eight different countries and treating approximately 3 million tonnes of concentrates and secondary materials per year. The process is currently used in both lead and copper smelting. The most recently commissioned plants were in Germany and China, one for treating scrap copper and the other treating low-grade copper concentrates. The Copper ISASMEL T furnace ("CIF") at Mount Isa Mines Limited ("MIM") has continued to set new operational records, with throughput of more than I million tonnes of concentrate per year and very low operating costs. This paper summarises the latest operational data from the Mount Isa Copper ISASMELT plant and outlines the successful approach to industrial R&D taken by MIM in the development of the ISASMEL T process.

Jan 1, 2003

By V. D. Tathavadkar

Chromite ore is of immense importance for the extraction of metallic chromium and chromium chemicals. The mineralogy and crystal structure of chromite phase are therefore important part of our investigation on the extraction chemistry of chromium species. In this investigation, we have studied the effect of the processing parameters, i.e., the temperature and the oxygen potential on the microstructure and composition of mineral phases formed in the Cr2O3 ?Al2O3 -FexOy -MgO system. In particular the importance of the spinodal decomposition reaction is emphasized in the extraction of chromium as sodium chromite and sodium chromate. Experiments were carried out in order to study the differences in the crystallography of different chromite minerals. Phase equilibria in natural chromite minerals were investigated by calcining chromite mineral in air, argon, and 5% hydrogen + argon atmospheres over a temperature range from 200 to 1200 °C. The effect of the oxygen partial pressure and temperature on the phase constituents of the calcined product has been discussed. The microstructural changes were examined using scanning electron microscope (SEM) and the changes in elemental composition in different phases were analysed by electron probe micro analyser (EPMA). The results obtained from EPMA studies were used to calculate lattice parameter of the spinel lattice, and these values were compared with the values obtained from X-Ray powder diffraction data. On the basis of the experimental data, the mechanism of the spinodal decomposition of complex spinel phases is described under the influence of oxygen partial pressure and temperature.

Jan 1, 2000

By lchiro Aoi, Hideo Nakae, Makoto Yoshida, Makoto Ishino

"The influence 6f gravity on the microstructure of unidirectionally solidified Cu-Pb monotectic, Ag-Si and Fe-C eutectic alloys is studied. In order to examine the influence of gravity in a lg environment, both the upward (opposite to direction of gravity) and downward (direction of gravity) unidirectional solidifications are carried out. The results are as follows: (1) For the upward solidified Ag-Si eutectic alloy, the eutectic Si continuously grows. On the other hand, in the downward solidified Ag-Si alloy, the Si grows discontinuously and disperses into the ex-Ag matrix. (2) No morphological difference in the eutectic growth is observed between the upward and downward solidified Fe-C eutectic alloys. (3) In the case of the upward solidified Cu-Pb monotectic alloy, a banded structure, which consists of Pb-rich layers and Cu-rich layers, is observed. However, such a banded structure -is not observed in the downward specimen. (4) The banded structure is not found in the upward solidified Cu-Pb-0.05 mass % Al and Cu-Pb-0.1 mass % Al alloys. In the Cu-Pb-0.05 mass% Al alloy, a fibrous -L 2 phase grows continuously parallel to the growth direction at low growth rate. Only 500 mass ppm addition of aluminum induces the morphological change of the monotectic L2 phase.IntroductionThe influence of gravity on the solidification of eutectic and monotectic alloys has been investigated in microgravity environments [l-9]. The purpose of these studies was to obtain a homogeneous microstructure of eutectic or monotectic alloys, most of which alloys tend to solidify with macro-segregation under gravity. However, in most of the previous experiments, e.g., in free fall systems, in aircraft or in space laboratories, the growth rate was too high to realize a planar solid/liquid interface. This would be due to the limited time for solidification. Thus, it was difficult to examine the influence of gravity on the planar coupled growth of the eutectic or monotectic alloy. In this study, both the downward U.D.S. (unidirectional solidification by gravity) and upward U.D.S. (opposite direction to gravity) are carried out in order to examine the influence of gravity on the coupled growth in a lg environment [l0, 11]. In the case of the downward U.D.S. using the current Bridgman method, the molten alloy must be confined between the crucible and the solid."

Jan 1, 2000

By M. D. Stephens

A new, one-step process for extracting titanium from titaniferrous materials has been demonstrated. In the process, depleted uranium tetrafluoride (DUF 4), a solid, is mixed with ilmenite (FeTi03) and heated to 900°C. Titanium is extracted in the vapor phase as titanium tetrafluoride (TiF4) and the DUF4 is converted to uranium-iron oxide. The process has been found to selectively fluorinate the titanium in ilmenite and is capable of producing high purity TiF 4 with very low iron content. TiF 4 can be collected by condensation or through reaction with a fluoride salt such as NH4F, KF, or NaF. The TiF4 produced from the process can be used to make titanium metal, titanium oxide, or fluorotitanate compounds. Since the fluorination process is highly selective for titanium, it avoids many of the separations and waste issues common to other titanium extraction processes.

Jan 1, 2001

By Fathi Habashi

The recovery of uranium from wet process phosphoric acid was applied on industrial scale in the 1940's by using octylpyrophosphoric acid as an extractant. Later, more efficient reagents were used, e.g., di(2-ethylhexyl) phosphoric acid and actylphenyl phosphoric acid. In the 1970's the rare earths in Kola phosphate were recovered in Finland and recently (1997) in Norway using HNO, as a leaching agent and di(2-ethylhexyl) phosphoric acid as solvent. It was demonstrated later on laboratory scale that both uranium and rare earths could be extracted from the rock by tributyl phosphate but at different pH values provided that the rock is leached with nitric or hydrochloric acids instead of the commonly used sulfuric. This new concept opens the way to the possibility of treating phosphate rock by in-situ, dump, or vat leaching for the recovery of phosphate values as well as uranium and the rare earths. Another solvent extraction process is used industrially for the purification of phosphoric acid using butyl and amyl alcohols.

Jan 1, 1998

By H. A. F. de Souza, Dana S. Mills, P. E. Burgener

"ICP-MS has moved from a laboratory curiosity to a functional analytical tool. This paper discusses how ICP-MS has been used to solve difficult analytical problems encountered when analyzing various mine materials. Comparisons between analytical techniques applied to the analysis of gold and the platinum group metals illustrate the advantages and problems of ICPMS when. applied to trace levels of some metals iri the presence of ore grade metals. Interferences and matrix effects are compared to ICP, AA and Neutron Activation. The necessity to select chemical extractions which are compatible with ICP-MS are also discussed.The ICP-MS techniques explained in the examples on Au and precious group elements (PGE) have validity in analytical problems encountered in testing of trace metals in the presence of major elements found in mine materials. Exploration and environmental testing are other areas that require the same analytical approach to quantify trace levels in the presence of major interfering elements normally associated with mining environments."

Jan 1, 1999

By Mingming Zhang, Mallikharjuna R. Bogala, Ramana G. Reddy

Steelmaking desulfurization slag samples were characterized using chemical, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) methods. The objective of this work is to investigate the occurrence of sulfur and phosphorus components in the slag samples and to identify their origin and associations with the iron phases. Thermodynamic calculations results confirm the presence of phosphorus and sulfur components in the slag sample at high temperatures (1400 to 1800oC). The main constituents of slag include Ca3SiO5 (28.1%), MgO (9.31%), Ca3(PO4)2 (9.18%), CaS (8.39%) and CaO (5.68%). The major phosphorus and sulfur components of the slag are Ca3PO4 (99.2%) and CaS (79.3%) respectively. Characterization studies indicate the presence of microparticles of different sizes and shapes in the slag sample. Elemental analysis of these particles confirm the presence of major elements (O, Mg, Al, Si, S, Ca and Fe) in the slag sample.

Jan 1, 2015

By R. E. Sundell, S. M. Correa

"A mathematical model is developed for the fluid flow in tungsten-inert gas weld pools. The fluid is taken to be incompressible, viscous, electrically conducting, and confined within a pool of specified shape. The flow is driven by surface-tension gradient (thermocapillary), electromagnetic, and buoyancy forces generally in this order of importance. Analysis indicates that the electromagnetic field may be calculated a priori and so decoupled from the nonlinear fluid mechanics and heat-transfer problem. The resulting set of equations is solved numerically by a line relaxation process. Computational errors caused by truncation in finite-difference schemes and by inadequate grid distributions are considered. The model is used to study several cases of differing heat and current input to the pool with and without surfactant-induced thermocapillary forces. The principal conclusions are that the thermocapillary flow, when present, is dominant with surface velocities on the order of 1 m/s. The heat transfer, as deduced from isotherms within the pool, is crucially dependent on the flow. Also, flow velocities and weld-pool surface temperatures were measuredand agree well with the model.2. IntroductionThe requirements of improved control and of automation in the TIG (tungsten-inert gas) welding process have led to the development of mathematical models for the heat transfer to the workpiece. It is now widely recognized that the fluid flow in weld pools sufficiently distorts the conduction heat transfer pattern to warrant inclusion in a process model. The experiments of Woods and Milner (1), among others, demonstrated that TIG weld pools could be driven by the electromagnetic J x B body forces present, J being the current distribution and B the induced magnetic field. Atthey (2) calculated that in typical pools the buoyancy force was about an order of magnitude less important - despite the large temperature gradients present - and neglected it in a computational study of the magnetohydrodynamic (MHD) flow. This work also reviewed many earlier studies of MHD flow caused by a source of current at a fluid surface, including analytical studies by Shercliffe (3), Sozou (4), and Sozou and Pickering (5), and a numerical study by Andrews and Craine (6). These works establish the importance of the electromagnetic force in the weld-pool flow."

Jan 1, 1986

By Rodney L. Williamson

Optimal estimation theory has been applied to the problem of estimating process variables during vacuum arc remelting (V AR), a process widely used in the specialty metals industry to cast large ingots of segregation sensitive and/or reactive metal alloys. Four state variables were used to develop a simple state-space model of the V AR process: electrode gap (G), electrode mass (M), electrode position (X) and electrode melting rate (R). The optimal estimator consists of a Kalman filter that incorporates the model and uses electrode feed rate and measurement based estimates of G, M and X to produce optimal estimates of all four state variables. Simulations show that the filter provides estimates that have error variances between one and three orders-of-magnitude less than estimates based solely on measurements. Examples are presented that verify this for electrode gap, an extremely important control parameter for the process.

Jan 1, 2001

By P. C. Chaubal

The overall kinetics of oxidation of single partic1es of chalcopyrite have been studied for temperatures up to 1273 K. The experiments were conducted in a stationary bed reactor using a non-isothermal technique. Any mass and heat transfer effects on the kinetics of oxidation were eliminated by using a high-enough gas flowrate. Up to temperatures of 873 K, pore-bl1ocking kinetics were applicable, whereas above 873 K, power-law kinetics gave a satisfactory fit of the data. The activation energy was 215 kJ/mol below 754 Kand 23.7 kJ/mol above 1,060 K. Predominance area diagrams were constructed at various temperatures and used in conjunction with X-ray analyses of partially oxidized samples to determine the intermediate phases formed during the reaction. The analysi1s also provides a justification for the kinetic models used. The results indicate that the reaction rate is first order with respect to oxygen concentration and inversely proportional to the square of the particle size throughout the ranges of temperature studied.

Jan 1, 1985

By Tapio Ahokainen, Asmo Vartiainen

"Outotec's portfolio contains a wide variety of smelting solutions for non-ferrous metals. Some of these include flash smelting for primary copper and nickel, flash converting for copper, Ausmelt technology for primary and secondary copper, nickel, tin, lead, and zinc residues and waste, Kaldo technology for secondary copper, lead, and precious metals recovery. Outotec also offers slag cleaning technologies and much more.Company provides complete process solutions tailored to each customer's individual needs. Decades of experience have resulted in extensive metallurgical know-how that ensures the most profitable process choice and optimal performance. Outotec's life cycle technology partnership with their customers spans from the early stages of process solution design through the supply and commissioning of the entire process chain. They include integrated process control and holistic service and support concepts. Continuous research and development ensures that the customer is provided with the latest advancements in process and equipment solutions.IntroductionOutotec develops and provides technology solutions for the sustainable use of the Earth's natural resources. Solutions are ranging from various processes and special equipment needed for metallurgical extraction and mineral processing of ores to the production of refined metals and minerals. The processes include not only the grinding and physical separation of ores but also the smelting and leaching of base metals and precious metals. The company provides engineering services for whole projects as well as life cycle services on the equipment and products that they supply."

Jan 1, 2012

By Qiang Zhong, Bin Xu, Qian Li, Yong-bin Yang, Tao Jiang, Yan Zhang

The occurrence of different ringing behaviors in oxidized pellet kiln for two kinds of coal (A and B) with similar properties, is difficult to explain based on the relationship between kiln ringing and coal properties. In this paper, the interaction of coal ash with pellet scrap powder was considered by studying the cohering behavior of powders consisting of them. The results showed that the cohering briquette strength of pellet scrap powder increased considerably when mixed with a small amount of coal ash; a maximum could be reached when the mass percent ratio of coal ash was 1.5%; the strength of powder mixed with coal B ash was always higher in same firing system. This obviously illustrated that coal B caused a more serious ringing problem. The relevant mechanism was that the stronger reactivity of coal B ash made cohering briquette have a more perfect crystallization and a more compact structure.

Jan 1, 2015

By James P. Bennett

EAF slag chemistry and its control have been recognized as important in producing quality steel at a low price for a number of decades_ EAF steel producers make lime and dolomite additions to furnaces, controlling the CIS ratios and sulfur pickup from the steel. Existing phase diagram data at 1600°C for CaO, MgO, FeO, SiO2, and Al2O3 was used to write a computer model optimizing slag chemistry for slag foaming and reduced refractory wear. The model, its development, and its use in an industrial steelmaking environment will be discussed along with how the model can improve energy efficiency. The importance of EAF mass balance to account for critical materials like Si in scrap and refractory wear using the model will also be emphasized_

Jan 1, 2003

By James P. Bennett

EAF slag chemistry and its control have been recognized as important in producing quality steel at a low price for a number of decades. EAF steel producers make lime and dolomite additions to furnaces, controlling the CIS ratios and sulfur pickup from the steel. Existing phase diagram data at 1600°C for CaO, MgO, FeO, SiO2, and Al2O3 was used to write a computer model optimizing slag chemistry for slag foaming and reduced refractory wear. The model, its development, and its use in an industrial steelmaking environment will be discussed along with how the model can improve energy efficiency. The importance of EAF mass balance to account for critical materials like Si in scrap and refractory wear using the model will also be emphasized.

Jan 1, 2003

By Akira Yazawa

The similarities and differences in copper, nickel and lead smelting processes are discussed based on the sulfur-oxygen chemical potential diagrams and the free energy minimization assessments using a thermodynamic software. The prominent features of copper smelting are ascribable to the fact that copper has a strong affinity for sulfur but weak for oxygen and the liquid phase immiscibility between Cu and Cu2S. During the oxidation of sulfides, nickel metal is not stable except at temperatures higher than 1500°C, well miscible with its sulfide, and is oxidized more easily than copper. Metallic lead looks as stable as copper during the oxidation of the concentrate but Pb and PbS. are much more miscible with each other and the vaporization loss is considerable. In the reductive smelting of oxides, the effects of oxygen potential and temperature on the copper contents in slag are not significant due to the monovalent character of copper and the reduction of copper content in slag is not easy in practice. The effect of the slag compositions on the oxidic metal contents of slag is much more significant for lead than either copper or nickel. Due to the immiscible nature between Pb and Fe, high grade lead bullion is easily obtained and lead is more tolerant to impurities.

Jan 1, 1998

By Ing. R. Geutskens

Zinc-bearing dust from blast furnace gas-scrubbing operation is a well known environmental health problem in the iron and steel industry. Hoogovens IJmuiden (The Netherlands) developed processes to solve this problem. 90% of the zinc is concentrated in 25% of the dust (the fine particle fraction) by means of slurry-hydrocyclonage. The resulting fine particle fraction is treated in a pressure leaching process. Hydrochloric waste pickle liquors have been used as a leaching liquor. By creating optimal leaching conditions more than 98% of the zinc is brought into an acid' solution, whereas nearly all the iron remains in the residue. The zinc can be separated selectively from the solution. The residue can be reused in the blast furnace (via the sintering plant). In the article information is given about the research work and -results of the pressure leaching process as well as the possibilities of the process for solving comparible problems.

Jan 1, 1990

By Metehan Erdogan, Ishak Karakaya, Fuat Erden

"Mg-Ni system draws attention due to the promising hydrogen storage properties of Mg2Ni. The proposed method involves the use of NiO and MgCl2 in an electrochemical cell to from Mg-Ni intermetallics directly. The electrodeoxidation of NiO was followed by combination of Mg and Ni in molten salt electrolytes. The products were characterized by XRD analysis and SEM examinations. The quantitative results from Rigaku supported by Rietveld Refinement method conducted by Maud showed that more than 50 percent of the input Ni was converted to Mg-Ni intermetallics.INTRODUCTIONIt is well known that fossil fuels are the most common energy producing materials throughout the last century although, they are not renewable and their usage cause critical environmental problems [1, 2]. Hydrogen, on the other hand, is known as a clean, renewable energy carrier and instead of fossil fuels; usage of hydrogen for energy production will be the benefit of mankind. However, there are problems that hinder more common usage of hydrogen such as hydrogen storage [3]. Mg2Ni is known as Mg based hydrogen storage material with high hydrogen storage capacity [3-6]. Common Mg2Ni production methods are; mechanical alloying [8-11], vacuum induction melting [12, 13], vacuum arc melting [14], combustion synthesis [15], melt spinning [16], repetitive rolling [17] and isothermal evaporation casting [18] were also used. However, in all of these, pure Mg and Ni are required to be produced previously. Therefore, difficulties arise during handling, preparation and combination of Mg and Ni due to highly reactive nature of especially magnesium (i.e. oxidation of Mg) [11, 17, 19, 20]. Although hydrogen desorption dynamics can be significantly improved with usage of nanostructured Mg2Ni [7], it is difficult and it requires very long processing durations to produce nanostructured Mg2Ni by above processes."

Jan 1, 2014

By Stephen Gale, David Clarry, Edmund Smith, Jon Feldman

"In 2006, a Canadian steel maker embarked on an ambitious initiative to become “Best in Class in Energy Management”. This initiative provides the framework for this paper, with some augmentation from other energy management projects carried out by Hatch. The initiative focused on identifying energy/GHG management improvements leading to low-cost implementation of energy savings or GHG emission reduction. The key components of the approach were:• Review site energy management practices and benchmark internationally.• Review best technical practices and benchmark against public energy intensity data.• Conducted a site-wide Energy Assessment and physical review of operating areas.• Facilitation of on site-workshops with staff to prioritize savings opportunities, as well as identify and remove implementation barriers.• Development of an Energy Management Action Plan for implementation of improvements.Most organizations can produce, with relative ease, a list of ideas for saving energy, implementing them is the challenge. This paper addresses these issues as well as the profitability of the energy efficiency improvements and the consequences for GHG emissions.IntroductionWhen one of the authors was an undergraduate engineering student at the University of Cape Town in South Africa, the technical drawing instructor made a statement that was both humorous, and mildly profound. He claimed that the most successful engineer is one who is both lazy and diligent. Lazy, in the sense that the engineer is constantly on the lookout for an easier, more efficient, way to do something. Diligent, in the sense that the engineer will work tirelessly to come up with a good technical solution for the easier way. This paper, somewhat of an anomaly in a compilation of technical proceedings, hopes to break the mould a little, and to show a “lazy-diligent” way of reducing the carbon emissions from an industrial facility, using a steel plant as an example."

Jan 1, 2008

By J. L. Holman

The Bureau of Mines is investigating recovery of Ni, Co, Cr, and other metals from mixed contaminated supera110y scrap. The scrap is melt-refined and cast into anodes for electrodeposition of recyclable Ni-Co alloy. Melt oxidation using roasted superalloy grinding sludge as oxygen source can divert the Cr to the slag but with excessive Ni-Co loss. Melt oxidation-carburization or direct melt carburization retains -95 pct of the Ni-Co in the anode alloy. With direct carburization, -90 pct or more of the Cr and other refractory metals report to the anode alloy, largely as carbide phases insoluble in electrolysis. Electrorefining data relate parameters such as controlled cathode potential, Fe and Cr impurities, pH, and compartmented cell use, to current efficiency and Ni-Co deposit quality. Recovery of -90 pct of the Ni-Co in the scrap can be achieved. Preliminary experiments to recover Cr, W, and other metals from the anode sludge and other byproducts are discussed. 347

Jan 1, 1987

By F. F. Aplan, G. Simkovich

"A review is given of the effects of solid state point imperfections upon a number of mineral benefication processes and a metal extraction process. It has been found in numerous flotation studies that small amounts of aliovalent impurities (dopants) in binary compounds may show major effects upon flotation behavior. Both semiconducting and ionic conducting compounds are affected. These effects are also seen in hydrometallurgical studies as well as in electrostatic operations. Additionally, de-copperization of lead melts appears to be strongly influenced by similar defects. It is hypothesized that the effects observed in these studies are present in actual operations and should be considered in designing processes. A few speculations concerning future efforts are advanced. IntroductionImperfections [point (e.g., vacancies, interstials, quasi-free electrons, electron holes, impurity ions), line (e.g., dislocations), two dimensional (e.g., grain boundaries) and three dimensional (e.g., 2nd phases) defects] are generally present in solid materials and these imperfections may, and often do, have important effects upon a variety of properties and processes. In general, one may, in most cases, attain elimination of three dimensional defects by a separation process of one type or another (e.g., gravity, electrostatic, magnetic, flotation, hydrometallurgical etc.,). Thus, this type of defect has rarely been investigated in a systematic fashion. Two dimensional defects are always present in non-single crystal materials but have also escaped systematic studies in processes primarily because the control of such defects is not easily attained. Line defects are non-equilibrium entities which are present in ill-defined quantities so that they present a variable that cannot be easily controlled although through careful systematic experiments one can attain some reproducible relations pertaining to this type of defect.Contrary to the lack of studies concerned with the effects of 1, 2 and 3 dimensional types of defects there has been some activity concerned with point defects and their effects upon a number of mineral/metallurgical processes, especially flotation processes. Thus, this article will present a review primarily of point defects in relation to their effects upon flotation although other processes and defects will also be mentioned."

Jan 1, 1988