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By C. J. Newman

In January 1999, a redesign of the Kennecott Flash Converting furnace settler was initiated to enhance furnace integrity and extend furnace life. This furnace uses Kennecott-Outokumpu Flash Converting technology to produce copper directly from copper matte. A detailed assessment was made of all technology available around the world before making a decision on the design features to be incorporated in the new design. The new design includes the following: redesign of all sidewall cooling elements to include the latest cooling element technology; redesign of the furnace hearth to include a stadium hearth at the reaction shaft end of the furnace; redesign of the furnace hearth to include a stepped hearth design adjacent to the furnace sidewalls; addition of flat settler roof cooling elements .around the reaction shaft; replacement of reaction shaft transition elements with an improved design and improvements to the furnace cooling element monitoring systems. The Flash Converting furnace was shut down on a planned basis in July 2001 to implement these improvements after 29 months of operation, converting more than 1,000,000 tonnes of matte. During the 30 day shut down, the improvements were successfully completed, with furnace start up in August 2001

Jan 1, 2002

By A. Rawat

The removal of oxyanions of arsenic present in mine process water and drinking water to a regulatory level is a challenging problem. Recently a patented adsorbent lanthanum oxide has been developed which has shown strong specificity for the anions of arsenic. In this paper the kinetic and thermodynamic aspects of arsenic adsorption on to lanthanum oxide are discussed. Adsorption tests were performed at different temperatures using synthetic solutions of arsenic of varying concentrations. From the kinetic data and adsorption isotherms thermodynamic properties such as Gibb's free energy, standard enthalpy of adsorption, standard entropy, isosteric heat of adsorption and activation energy were determined. The results showed that temperature had a positive effect on the rate and degree of adsorption:The activation energy decreased with increase in the initial concentration thus indicating solute-solute interactions in the system. Also, the isosteric heat was found to decrease with increase in the adsorption density implying a heterogeneous adsorbent surface.

Jan 1, 1998

By Allan MacRae

Freeport-McMoRan Inc. operates an ISASMELTTM furnace for the smelting of copper concentrate at the Miami Smelter in Claypool, Arizona. In May 2017, the furnace was restarted after incorporating newly designed copper cooling elements from just above the tap hole to the underside of the roof. The objective of the improved cooling design was to extend campaign life by eliminating existing failure mechanisms with the wall refractory. In addition to upgraded bathline coolers and complete coverage of the gas offtake transition, or ‘kettle’, with plate coolers, a novel arrangement of coolers was installed in the remaining freeboard area. The shell required significant cutting and re-stiffening, as well as extensive modification of the cooling water piping. Based on performance observed to date, it is expected that smelter throughput will be increased due to extended ISASMELTTM refractory campaign life.

By V. I. Lakshmanan

The demand for elements such as nickel, cobalt, titanium and gold in various applications has increased significantly. Innovation to recover these elements now plays a major role in metallurgical processes as established technologies have challenges in treating the types of ores that are available while meeting the increasingly stricter environmental regulations. Alternative chloride based processes have been developed that can be used to recover the value elements from the available feed stocks with potentially lower environmental impact. Chloride-based hydrometallurgical processes have several advantages, including higher leachability of complex ores/tailings and relative stability of chloro-complexes of the metals. Process Research ORTECH Inc. (PRO) has developed mixed-chloride process flowsheets, where innovative solvent extraction process steps are used for the separation of nickel, cobalt, titanium and gold from their respective chloride solutions. This paper will discuss the potential aqueous chloro-chemistry of these metals and separation reaction mechanisms involved in the solvent extraction process.

By K. Alibhai

Greek laterites, which generally had nickel concentrations of < 1 %, are amenable to chemical leaching,. although there is considerable variability in the ease of leaching with different ore types. With low grade ores(< 1 % Ni content); >70% of the nickel was leached in columns with a strong selectivity for nickel over iron. Heterotrophic microbially assisted leaching could be a viable alternative to classical hydrometallurgical and/or pyrometallurgical techniques, with a very high recovery (greater than 80% ) being found with some of these mineral microbial interactions. Critic acid was probably the effective chelating agent.

Jan 1, 1991

By Vadym Drozd, Yongzhou Sun, Shah Najiba, Jiuhua Chen, Andriy Durygin

"Phase transitions of the potential hydrogen storage compound, ammonia borane (NH3.BH3), was investigated using Raman spectroscopy and a diamond anvil cell at high pressures up to 9.5 GPa and low temperatures down to 90K. At room temperature, ammonia borane has three phase transitions in this pressure range. Upon cooling, four new phases were discovered through changes in characteristic Raman spectra. This result provides information about the stability of new bonding characteristics of this potential hydrogen storage material at low temperature and high pressure region.IntroductionDevelopment of hydrogen technology requires the safe, efficient and environmental friendly materials for hydrogen storage and hydrides have attracted much attention as hydrogen storage media. Among chemical hydrides, ammonia borane (BH3NH3) stands out due to its high gravimetric and volumetric hydrogen density ' "". Despite high hydrogen content, this compound is very stable. It releases hydrogen in several steps by thermal decomposition in the temperature range of 100°C to 500°C. Direct thermal decomposition also causes toxic borazine emission. Recent research interests on ammonia borane include destabilizing this compound to lower the dehydrogenation temperature with an enhanced hydrogen release rate using different techniques, e.g. the nanoscaffolds'', ionic liquids"" and acid'"" or transition metal catalysts' ""'. As a molecule of ammonia borane consists of protonic (NH) and hydritic (BH) hydrogens bonded by the polarized dative bond, thermal or catalyzed decomposition requires breaking of N-H and B-H bonding. Still now, the detailed information about the bonding characteristics of ammonia borane is not sufficient to understand details about its phases and structures. The development of methods to enhance hydrogen discharge rate from ammonia borane requires a detailed study about the structural and dynamical properties that control the stability and the intermolecular interactions of this material. This study is motivated to investigate the stability of the existing phases and also to explore the existence of any new phases at different temperatures and pressures which may have enhanced hydrogen release and uptake properties."

Jan 1, 2012

By Wenjun Duan, Zongliang Zuo, Qingbo Yu, Qin Qin, Junxiang Liu

Moving bed has been widely used in the field of heat and mass transfer and reaction between solid particles and gas. In order to enhance the heat exchange coefficient, there will be tube banks inserted in the moving bed. In the process of drying ammoniates particles or heat recovery from high-temperature particles with moving bed, the particles flow behavior around the tube banks is significant. In this paper, the particles flow behavior around the tube banks is investigated, and all the results can provide guidance for the design and operation of a moving bed.

Jan 1, 2016

By Patrick R. Taylor

A non-transferred arc thermal plasma assisted cyclone reactor has been designed, built and operated to evaluate its use in vitrification of wastes. Simulated waste (liquid, slurry or fine particulate) is injected near the plasma flame, where nearly instantaneous dehydration and calcination reactions happen. A non-transferred arc plasma torch was attached tangentially to the cyclone and is utilized as both an enthalpy source and to provide the gas velocities required to generate the cyclonic gas flow patterns. The closed top cyclone flow sends the solid particulates to the wall, where they are captured by a thin film of molten glass that is injected as a powder at a position lower in the reactor. The molten glass is then collected in a crucible. The feasibility of simulant injection directly into the flame zone and its effect on electrode lifetimes has been studied. Several candidate refractory systems have been evaluated for their suitability for extended use under the demanding conditions present in the cyclone reactor.

Jan 1, 2002

By Kandipati Sreenivasarao

Ion and precipitate flotation involve adding an appropriate collector to aqueous solutions containing metal ions, to form hydrophobic metal-collector complexes or precipitates that can be removed by flotation. With a better fundamental understanding of the effects of physical, engineering and chemical parameters on the performance, ion and precipitate flotation techniques could usefully complement techniques now available for removing metal ions from dilute solutions. The removal of Cu(II), Pb(II), Cd(II), Cr(III) and Cr(V1) has been studied, using different types of collector, according to the nature of the metal-bearing species. The effects of collector/metal ion ratio, and solution and froth height on the flotation kinetics, bubble coverage by the metal-collector complex, recovery of metal and effluent quality are reported. The observed behavior is related to the solubility products of the metal-collector complexes, which were also determined.

Jan 1, 1994

By A. Shemi

Tungsten carbide scrap (WC–Co) is material generated from the tungsten carbide manufacturing process and worn out or used carbide parts from industry. Tungsten (W) ores contain about 3 wt% WO3 and their W concentrates about 10– 75 wt% WO3. Tungsten carbide scrap typically contains 40–95 wt% W. The high intrinsic value of W and the fact that the least valuable scrap contains more W than the average tungsten ore makes tungsten carbide scrap a worthy material for re-use. This study has investigated the selective dissolution of the cobalt (Co) binder phase, and recovery of tungsten monocarbide (WC) and Co using an acid leach process. The Co component was selectively leached leaving the WC solid particles intact. Further investigation using a complexing agent-aided acid leach process that takes advantage of organic chelating agents that form a soluble tungsten complex in place of the passive insoluble tungsten oxide is envisaged. The optimal dissolution of the Co binder phase using an inorganic acid in conjunction with an organic complexing agent is a novel approach with the potential of reduced leaching times and possibility of regenerating the unreacted organic acid.

By Jose R. Parga

In mining operations, cyanidation is the ,predominant method by which gold and silver are recovered from their ores and it is recognized that cyanide consumption can be a major factor that contributes to the operating costs for such operations. Also after extraction and recovery of precious metals a certain amount of cyanide is delivered to the tailings pond and must be considered with respect is environmental problems due to the toxicity of cyanides. In this regard, the Air-Sparged Hydrocyclone (ASH) has been used as a reactor for the treatment of cyanide solutions in two ways; first for cyanide recovery by acidulation using the Mexican modification of the Mills-Crowe process and second for cyanide destruction by oxidation with the use of chlorine dioxide (ClO2). In both cases, excellent performance can be achieved using the high capacity ASH system.

Jan 1, 1998

By T. Nagano

Mitsubishi Metal Corporation started the development work of a new process for continuous production of copper in 1961. After a series of experimental and semi-commercial operations, the first commercial plant of the Mitsubishi Continuous Copper Smelting and Converting Process was put into operation in March, 1974. The new plant, which has a design capacity of 4,000 metric ton copper per month, was built within the premises of Naoshima Smelter, replacing the old No.1 reverberatory smelter there. The SO2-rich exhaust gas from this new plant is blended with the off-gas of the No.2 reverberatory furnace for production of sulfuric acid and the overall emission of sulfur at Naoshima has been greatly reduced. The operation of the continuous plant has been satisfactory and several advantageous features of the Mitsubishi Process have been proven on a commercial scale. This paper first gives a brief description of the history of the development work and the characteristic features of the process. The paper then describes the new commercial plant and operating data obtained so far.

Jan 1, 1976

By M. El Ganaoui, P. Bontoux

"A computational model to investigate solid/liquid phase change transitions for binary alloy under directional solidification is presented. Conservation equations are developed by using an homogeneous formulation. A second order accuracy method of time and space based on finite volume approximation has been evaluated by comparing results to spectral solution for time-dependent solutal convection developping in a melted alloy. For extended model to solid/liquid interface effects time amplification of solutal perturbation injected near the interface is described before considering solutal convection is melt.IntroductionThe enthalpy method gives a front fixing approach for energy equation without introducing coordinate transformation. The interfare position is recovered a posteriori [1]. A number of authors have extended this approach so as to include the convection phenomena within the two phase 'mushy region' [2, 3, 4, 5, 6].We have developed a time-dependent enthalpy-porosity formulation for directional solidification [4, 6, 8]. The interaction between solid and liquid phases is modelised by a Darcien type force in the phase change area. The behaviour of the melt is similar with the flow of an incompressible fluid in a porous medium. This force is proportional to the relative phase velocity. It corresponds to a damping force depending on the anisotropic permeability of the 'mushy zone'. The permeability depends on the liquid fraction and on the size of·solidification microstructures. An informative discussion of a new slant on the general approach of continuum mechanics needed to analyze the formation of mushy zone is given in [12]. The method is extended to the presence of species diffusion: the solutal Stefan condition which expresses the solute incorporation or rejection across the interface is accounted implicitly in a species equation valid in all the domain [14, 15]."

Jan 1, 2001

By Florian Kongoli

The behavior of cobalt as a by-product in the NilCu smelting and converting processes effects directly the quality of the final products as well as the revenues gained from the overall process. An effective way to evaluate and predict this important behavior is thermodynamic modeling which reduces the time and the cost of experimental investigation. In this work a thermodynamic model of cobalt-containing matte phase in NilCu smelting and converting processes is presented. The model predicts a priori the thermodynamic properties and phase relations of the ternary and multicomponent matte based solely upon the optimized parameters of the binary systems. This model can be used with other models such as those of slag, metal, gas etc. to predict various aspects of cobalt behavior such as matte- slag, metal-slag distribution, etc.

Jan 1, 1999

By John W. Ahlrichs

Microscope, electron microprobe and x-ray diffraction have been used to provide quantitative evaluation of products from the mill, smelter, refinery and other metallurgical processes. Phase compositions and their quantities are necessary for an adequate understanding of the various products obtained throughout an operation and in laboratory testing. By careful evaluation, important information can be gained in improving recoveries and increasing grades at various stages of processing. Four case histories are discussed in this paper. Quantitative microscopic counting techniques are applied to mill products to determine degrees of locking and liberation of the economic minerals. Rapid, but accurate evaluation aids the metallurgist to develop or improve the grinding and flotation circuits. In the smelter, the identification and quantification of the phases are important for predicting reaction mechanisms and kinetic trends. Mineralogic techniques have been applied to conventional smelter products, and to those obtained in laboratory tests for newly developed innovations to smelting. Small, but important, values of gold occurrences in ore are difficult to determine. Evaluation of gold usually requires special separations into various mineral concentrates, followed by assays and mineralogic determinations of the products. Numerous occurrences of solid solution constituents can be treated as by-products, but often they are deleterious to metallurgical treatment. Most solid solution problems can be unraveled by the mineralogist&apos;s tools.

Jan 1, 1981

By A. Hasko

Phytoremediation is a new low cost alternative technique for remediation of contaminated soils from heavy metals that are emitted by ferrous and nonferrous mining and extracting processes. It is based on the possibility to use several plants that accumulate high level of metals in order to remove metallic pollutants from soils and render them harmless. Phytoextraction is an adjacent new technique that uses these hyper-accumulator plants in order to extract the metals from them using even the conventional smelting or refming processes. In our previous work, an extensive investigation of about 150 plants have been carried and several species were identified that could be used for nickel phytoremediation and phytoextraction because of their high accumulation of nickel. It has been found that five taxa from Alyssum genus specie had the highest ability to accumulate nickel with concentrations more than 10000 ug/g (dry weight) or 1%. The taxa showing the highest accumulation of this metal is Alyssum murale var. chlorocarpum with 28 600 ug/g or 2.86%, a good candidate for Phytoextraction. In this work, in order to optimize the phytoremediation and phytoextraction processes further Absorption Spectrometry measurements and biological studies were carried out to determine the parts of the plants that accumulate the highest amount of nickel and the best biological cycle during which they accumulate the highest amount. The results show that the greatest accumulation of nickel occurred in the leaf material (2.86%) and the least in the roots (0.43%). The investigation of the biological cycle of the genus Alyssum showed that: (1) the seeds germinated between 50 C to 30 0 C and more in 25 0 C; (2) 62.9 % of seeds germinated at A.m. var. chlorocarpum; (3) the emergence is almost continue from March to April; (4) the anthesis occurs from May to July; (5) the ripening of the fruit takes place 30 days after flowering; (6) the dissemination of fruits occurs from September to October. Due to these special characteristics it is reaffirmed that Alyssum murale var. chlorocarpum, as a nickel hyperaccumulator, is the most promising plant to be used for feasible phytoremedation and phytoextraction purposes. Keywords: Key words: Phytoextraction, PhytoRemediation, Nickel accumulators, Alyssum sp., Biological cycle

Jan 1, 2003

By H. Jiang, S. Yang

"The main processes for nickel metallurgy in China consist of electric arc furnace smelting to produce low grade nickel matte and converter to high grade nickel matte, grinding and flotation to separate nickel sulfide from copper sulfide and direct electrolysis of nickel matte. Systematic studies on the properties of electric furnace slag, smelting process for nickel matte, anodic process of nickel matte, cathodic process of nickel electrolysis have been done in our labs. In addition, an approach to a new hydrometallurgy process for nickel matte has been done. The feature of the new process is one stage acidic leaching of high grade nickel matte. The leaching solution could be purified by deposition way or by solvent extraction way. There are two leaching rate-determing steps, chemistry reaction-determing one at temperatures below 600C and diffusion-determing one at temperatures higher than 600 c. The acidic leaching fraction reacted dvaties with leaching time t according to the equation 1-(1- a ) 1/3=kt. The experimental data also show that the leaching reaction rate varies with concentrations of H+, Cl-, and it is also effected by copper sulfide and Cu++. The Cu++ ion can retard the leaching reaction due to forming a copper sulfide layer on the matte surface and the equation 1- 2/3 a. - (1- a: ) 2/3 akt can be used for the case. However the copper sulfide added into nickel matte can facilitate the leaching process. The research work for nickel metallurgy done by others in China has also been mentioned in this paper.Large scale production of nickel in China started in 1960s.The main processes consist of electric arc furnace smelting to produce low grade nickel matte and converter to high grade nickel matte grinding and floatation to separate copper sulfide from nickel sulfide and direct electrolysis of nickel matte.To reduce nickel loss in slag a reseaech group organized by Jinchuan Company and Central South Institute of Mining and Metallurgy (now the Central South University of Technology) measured the viscosity surface tention density conductance melting point and structure of the slag(I).lt has been found that the physico-chemical properties of the slag depend on the components SiO2 ,MgO and FeO but FeO in the slag is too high and the statistic analysis of data from industry gave an equation to correlate the content of Ni in slag with the content of Ni in matte and the composition of slag again it was pointed out that the content of FeO in slag effected the loss of Ni in slag very much (2). The ratio (FeO+MgO) to SiO2shouid be less than 1.13 and the content of Fe3O4should be as low as possible but the reaction"

Jan 1, 1988

By D. E. Karvelas

Argonne National Laboratory is conducting research to develop a cost-effective and environmentally acceptable process for the separation of high-value plastics from discarded household appliances. The process under development has separated individual high purity (greater than 99.5%) acrylonitrile-butadiene-styrene (ABS) and high-impact polystyrene (HIPS) from corruningled plastics generated by appliance-shredding and metal-recovery operations. The process consists of size-reduction steps for the commingled plastics, followed by a series of gravity- separation techniques to separate plastic materials of different densities. Individual plastics of similar densities, such as ABS and HIPS, are further separated by using a chemical solution. By controlling the surface tension, the density, and the temperature of the chemical solution, we are able to selectively float/separate plastics that have different surface energies. This separation technique has proven to be highly effective in recovering high-purity plastics materials from discarded household appliances. A conceptual design of a continuous process to recover high-value plastics from discarded appliances is also discussed. In addition to plastics separation research, Argonne National Laboratory is conducting research to develop cost-effective techniques for improving the mechanical properties of plastics recovered from appliances.

Jan 1, 1996

By Ben Bowman

For certain ferroalloy furnaces, such as ferrochrome or ferromanganese, there is still doubt about the mechanisms operating under the electrode tips. In this paper a model is built that does not call upon an arc. The medium is best described as an electrically conducting slurry, a mixture of liquids, solids and gas. There are two sources of propulsion, the Lorentz force within the conducting part and buoyancy generated by CO bubbles, creating two opposed poloidal circulation loops, downward below the electrode axis and upward further out.

Jan 1, 2014

By Yan Beygelzimer, Alexander Spuskanyuk, Victor Varyukhin

"A cellular model of the plastic deformation of polycrystalline aggregate is proposed and comprehensively described. Representative volume element (RVE) of a solid body, that is being deformed, is described as a population of interconnected units that, in turn, can consist of lower scale level units. Sliding along the various allowed sliding systems deforms simple units, which do not have an internal structure. For consideration of stress distribution within the limits of components, the approach of self-consistent field is used. Rotation of units and moment stresses connected with it are taken into account. Results of computer experiments are analyzed.1. IntroductionMicromechanical models of polycrystals are a link between the research of plastic deformation on micro and macro levels. Computer simulation of inelastic strain of polycrystals has found a great deal of interest as well. Despite the fact that this approach does not allow to obtain macroscopic constitutive relationships that are used in deformed solid body mechanics, it clarifies essential features of the phenomena in many aspects. First of all, it concerns effects stipulated by interdependence of micro-level and macro level of plastic deformation processes. Also, with the computing mechanics, instead of constitutive relationships, the adequate computer models can be used. Broad possibilities for computer simulation of various processes are opened by cellular automata approach. By means of numerical experiments, the cellular automata allows to study the macro behavior of the whole ensemble of cells depending on the local microscopic laws that define evolution of each cell and its interaction with the closest environment.We propose a mathematical model of a polycrystalline aggregate (the cellular model) based on a self-consistent scheme and on the interaction law similar to the one by Berveiller and Zaoui [1]. Our original solution is the self-similar structure of cellular automata that allows modeling of the fractal nature of real materials (Figure 1). The goals of this work are to present the major structures and relations of cellular model of polycrystal and to test this model for its adequacy as for describing known effects and dependencies. Identification of the model and its application for studying of concrete polycrystals are put aside for the future research."

Jan 1, 2001