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By Ari I. Kogut

Impurity minerals in fluorspar ores and concentrates from a deposit in Southern Africa have been studied by reflected light, transmitted light, and cathodoluminescence microscopy. The principal impurities are quartz, calcite, aegirine, apatite, ankerite, magnetite, goethite, and synchysite [Ca(La,Ce,Nd)(C03l2Fj. Cathodoluminescence microscopy was found to be very useful in studying the character of the fluorite and especially for recognizing the presence of apatite and calcite impurities. Fluorite exhibits blue, calcite shows yellow, and apatite has white, light purple, and pink cathodoluminescence. The cathodoluminescent character of apatite varies with its geological environment and position in the orebody. The results of this microscopic study show that phosphorus present in flUorite concentrates occurs principally in binary locked apatite-fluorite particles. Successive fluorite cleaner concentrates contain progressively smaller amounts of locked apatite-fluorite particles. Free apatite has been effectively partitioned to the final tailings.

Jan 1, 1995

By Jing Lin, Yuan Xu, Qingcai Liu, Dengfu Cheng

"Smelting reduction technology has been developed greatly in recent years. But one of the key problems for this technology is about the refractory that used as lining material in the molten bath. Investigation and test shown that corrosion rate of refractory was much higher and the corrosion mechanism was much more complexity in the molten bath of smelting reduction with iron bath than that of the blast furnace and rotary furnace technology [l-5]. The corrosion behavior and corrosion rate of Al2OrC-ZrO2 series refractory in the melt of smelting reduction with iron bath have been studied by rotary immersion and quasi-static immersion test in this paper. The major factors that affect the interaction between the melt and refractory were investigated. The test results shown that the corrosion rate of AI2O 3-C-ZrO2 series refractory decreased with the ZrO2 increasing when ZrO2 content was from 3% to 10%. Ferrous oxides content, relative moving speed between the melt and refractory and temperature of the molten bath were the important factors that affect the corrosion rate. But the ferrous oxides concentration was the most important one. The corrosion rate was increased as a linear relation with the rising of ferrous oxides content of the melt. The corrosion rate in the quasi-static immersion was much less than that of the dynamic immersion (rotary immersion) for the Al2O 3-CZrO2 series refractory in the same testing condition. The corrosion mechanism of Al2OrC-ZrO2 series refractory is: graphite oxidized in advance, then interaction between the constituents of refractory and melt taken place and deteriorate layer of refractory and new compounds were formed, the properties of refractory was changed.IntroductionSmelting reduction with iron bath is a typical technology [3, 4, 6]. The obvious features of the melt for smelting reduction technology with iron bath are much higher ferrous oxides and much more complexity melt composition and structure than that of the blast furnace technology [2, 5-8]. The properties of the melt were changed dynamicilly and constantly in reduction process. On the other hand, the behavior of the melt depends on the activity and the reduction rate of ferrous oxides in the molten bath[9]. Because of the high concentration of ferrous oxides in slag and high reduction rate in the molten bath, the corrosion behavior and corrosion mechanism of the refractory lining by melt are an important factor in development of the technology of smelting reduction with iron bath. Up to now, improving refractory quality to anti-corrosion of melt and developing high quality and long term refractory used as the lining refractory materials in the molten bath of the final reduction furnace are also the most important questions for developing smelting reduction technology."

Jan 1, 2000

By Dieter Neuschiitz, Pengfu Tan

"In order to understand the sintering phenomena during iron ore sintering process, a CFD model of iron ore sintering has been developed, combining with the kinetics of 15 relevant chemical reactions with the aim of describing the temperature fields and the gas flow patterns in the sintering bed. This CFD model can be used to simulate the concentrations of the gaseous and solid species, temperatures of the gas and solid, melting and molten fractions of the mixture, gas velocities, temperature zones and residence times of the gas in each temperature zone. IntroductionThe off-gas analyses clearly revealed that the off-gas of a sinter strand does not have a composition corresponding to thermodynamic equilibrium, for example, the CO, CO2 and O2 concentrations are not the mutually consistent equilibrium values. Apparently the chemical reactions in the sinter bed are controlled kinetically. Therefore kinetic modeling of sintering reactions combined with CFD modeling is necessary to understand the sintering phenomena during iron ore sintering process.Several models of iron ore sintering have been developed since 1970 [l-l 4l, each being more refined than its predecessor. The models were formulated as a series of differential equations to describe chemical and physical changes occurring at a point in the bed. These equations were solved numerically in a vertical plane along the strand. The present CFD model, based on the Nath's model [14], has been published in the reference [15]. In this work, some new chemical kinetic models of gas-solid reactions are incorporated in the present CFD model. The concentrations of gaseous and solid species, temperatures of gas and solid, melting and molten fractions of solid, velocity of gas, and residence time of gas in each combustion zone can be calculated by this model."

Jan 1, 2004

By Hideharu Fukunaga, Jin Pan

"The recognition of Metal Matrix Composites (MMCs) as a means of providing high specific strength, high specific stiffness, excellent wear resistance, low thermal expansion and improved high temperature properties has led to a number of new processing, not previously used for plastic and ceramic matrix composites. As a primary fabricating process, the liquid methods are the major ones, which are reviewed briefly from the view of processing terminology. One of them, squeeze casting process is the most traditional and well-developed, because it is rapid, versatile and near-net shape production of materials. Two of new squeeze casting processes are presented to offer the hardness· controlled MMC and the· functionally graded MMCs as well as a newly developed whisker preform.I .IntroductionA large number of liquid processes and techniques including semi-solid liquid process are proposed. The most primitive process is ''pressure infiltration casting” of liquid metal into the fiber preform. It is called as follows depending on pressure and its source squeeze casting (1-4) by hydraulic ram, gas pressure infiltration casting (5, 6), vacuum infiltration, centrifugal casting (7), Lorentz-force-driven infiltration (8). The pressurizing on the liquid metal requests a large and stiff equipment, so pressureless infiltration technique has been developed using K2ZrF6 flux (9,10) while the mechanical properties are not high enough, and using H2 gas with Mg alloying element called pressureless infiltration casting (11-13), spontaneous infiltration process (14) and PRIMEX (15). In those processes, no severe reaction occurred between the reinforcement and matrix molten metal. In early l 990's, the reactive processing with pressure or without pressure, in which one material is totally transformed into another of the required shape, eq. assisted oxidation, has been developed, called reaction squeeze casting (16,17), DIMOX (18) reactive infiltration casting (19,20), and in-situ process (21,22). Die casting of SiCp/Al alloy (23,24) and thixocasting of SiCp/Mg alloy (25) are also applied to produce the machine component of MMCs."

Jan 1, 2000

By M. B. Sizgoric

Quantitative mineralogy is used in a study done on an Inco Metals Company nickel sulfide occurrence from 'the Thompson area in Northern Manitoba. The study included: a) determination of the variations in chemical composition of the ore minerals; b) determination of the liberation of the ore minerals for the various types of ore and for different feed grinds; c) assessment of the preliminary mill test results by comparing the mineral distribution in the different tailings. Preliminary mill test results had outlined three main problem areas: 1) unacceptabiy low grade concentrate with, 2) very high weight recovery and, 3) low pyrrhotite rejection resulting in a high sulfur concentrate. The mineralogical study readily explained these results by showing that: 1) between 20 and 40% of the nickel in the feeds and 55 and 75% of the nickel lost in the tailings is associated with pyrrhotite. This accounts in part for the low grade of the concentrates obtained at high recoveries: 2) hexagonal nonmagnetic pyrrhotite constitutes over 90 percent of pyrrhotite. Since hexagonal pyrrhotite floats more readily than monoclinic pyrrhotite, this could be part of the reason for the undesirable high pyrrhotite recoveries into the concentrates. Further test work to establish both the optimal grind and the best conditions for pyrrhotite rejection is therefore mandatory.

Jan 1, 1981

By T. K. Bundtzen

Placer gold in the Iditarod and Innoko mining camps of western Alaska is derived from a suite of comagmatic, Late Cretaceous to Early Tertiary, alkali-calcic, meta-aluminous. volcanic-plutonic complexes and peralumi-nous rhyolite sills that intrude Mesozoic flysch. Heavy-mineral concentrates from 42 mining operations and streams draining known mineralized areas in the igneous complexes contain placer gold and a variety of ore minerals derived from epithermal to hypothermal conditions of formation. The minerals include cassiterite, ilmenorutile, samarskite, cinnabar, scheelite, chromite, stibnite, silver sulfosalts, monazite, and zircon. Results of the study show that 1) cinnabar. stibnite, and quartz formed with the bulk of the placer gold in an epithermal lode environment, 2) chromite appears to have originated in mafic phases of monzonite plutons and alkalic basalts, and 3) niobium-tin-tungsten-uranium-silver values may have been derived from stockwork accumulations in cupolas of monzonite plutons.

Jan 1, 1987

By Ho-Sang Sohn

The kinetic study on desulfurization of copper matte by gas bubbling was designed under the presumptions of lower FeO activity and of no slag formation, Copper matte with 59% Cu and 22.6% S in weight was oxidized at 1523K by bubbling of Ar + O2 gas through a submerged nozzle. The effects of oxygen partial pressure and flow rate of gas on the oxidation rate of matte were discussed. The desulfurization rate and the evolution rate of SO2 gas of copper matte were significantly influenced by the oxygen partial pressure, but the dependence on gas flow rate was rather complicated. The desulfurization rate and evolution rate of SO2 gas of copper matte were described by the mass transfer rate through the gas film around the rising gas bubbles. Thermodynamic correlation equations between the partial pressure of gaseous species and matte composition were incorporated to the kinetic calculation, The present model shows that the reaction path starts to transiently cross over an isobar line of PSO2 to asymptotically approach to the particular isobar line drawn in a matte composition plane of %S and %O.

Jan 1, 2003

By François Larouche

Since their commercialization in the early 1990s, lithium-ion batteries (LIBs) have become ubiquitous for powering a myriad of portable electronics. Their usage now extends to the automotive industry and stationary energy storage market. With an average life of 6.2 years and the strong demand, the volume of spent LIBs has increased exponentially, making recycling mandatory. Currently, recycling/ recovery of spent LIBs is limited in comparison to all other types of batteries. The current processes focus mainly on the recovery of the most valuable metals such as cobalt and nickel, leaving lithium and phosphate in a low value end-product. It is necessary that new advanced recycling technologies are developed for the recovery of spent LIBs both from an economic and environmental perspective. In this paper, the current R&D status of LIBs recycling is reviewed with the emphasis placed on hydrometallurgical processing opportunities for Li-ion and Li-solid state batteries.

By E. James Quinn

Solvent extraction technology using EHEHPA (2-ethylhexyl phosphonic acid, 2-ethyhexyl mono ester) is the norm for industrial separations of rare earth elements. This process has some shortcomings, including a large number of stages compared to most SX processes and high acid requirement for stripping of the heavy rare earths. In this work, we examine a number of alternative mixed solvent extraction systems: (i) Mixtures of organophosphonic and phosphinic acids such as EHEHPA/Cyanex 272 or Cyanex 572; (ii) Ionic liquid mixtures of EHEHPA with quaternary ammonium chloride (Aliquat 336); and (iii) Mixtures of carboxylic acids for yttrium/lanthanide separations. We discuss and compare the efficacy of these systems with reference to the Nd/Sm separation, which is of industrial significance. Based on the extraction chemistry and the use of modelling tools to define the counter-current solvent extraction circuit, we present a techno-economic analysis of a separation plant and discuss the impact of various solvent systems on the capital expenditure (CAPEX) and operating costs (OPEX).

By Torma A. E.

Biotechnological processes are considered to be cost effective especially for situations where the recovery of metals from 'Very large volumes containing trace metal concentrations (less than 10 ppm) is concerned. Microorganisms, alive or dead, or their products can be highly efficient and selective biosorbents for metal concentration. It is important that the metal bound to the biosorbent can be stripped by suitable agent(s) and regenerated for repeated use. The stripped solution should be concentrated enough to be introduced into the common metal recovery circuit. The industrial acceptance of biosorption processes is dictated by increased competitive advantage over other processes. This paper reviews the pertinent literature?, regroups the information, and points out future possibilities for the mineral and metal processing industries.

Jan 1, 1992

By Michael J. McGuire

Rostoker, Inc. has developed a process to smelt solid hazardous/non-hazardous inorganic wastes. Near seven hundred experiments were performed. Actual industrial wastes as well as reagent grade chemicals were used. By mixing a multiplicity of these wastes to proper formulations, then furnacing them, it was determined that saleable end products could be reclaimed; metal, fume and slag. The slag, due to its siliceous structure was tested to be leach resistant (40 CFR). This formed the essence of our patent, #5,180,421 "Method and Apparatus for Recovering Useful Products from Waste Streams". What is unique is that a HTMR (High Temperature Metal Recovery) process has been developed that can treat a multiplicity of wastes within the same furnace. The discussion will include a list of waste streams we have treated, details of proper waste formulation and experimental results.

Jan 1, 1994

By Ross W. Smith

Microorganisms are increasingly finding use in mineral processing and hydrometallurgy both for the enhancement of mineral engineering operations and for the remediation of mineral industry wastes. Some of the applications, such as biologically assisted leaching of sulfide ores and biooxidation of refractory sulfide gold ores, are established commercial processes. Others, such as the use of organisms for the removal of heavy metal ions from dilute aqueous streams, are nearing commercial application. Other uses of microorganisms are potentially possible. These include use of microorganisms in leaching non-sulfide ores, the flocculation or flotation of minerals and remediation of toxic chemicals discharged from mineral engineering operations.

Jan 1, 1993

By Stavros A. Argyropoulos

Exothermic mass transfer takes place in various areas involving metallic systems, ranging from liquid metal processing operations to the growth of thin films in microelectronics. The formation of intermetallic compounds plays an important role in the exothermic mass transfer of metallic systems. Two types of exothermicity are identified , namely , Microexothermicity and Macroexothermicity. The former is encountered when small amounts of metals are mixed, while the latter is exhibited when a solid metal in a lump form is added into liquid metal. In this paper two types of exothermic mass transfer in metallic systems will be presented and reviewed. Mathematical modelling work for these types of exothermic mass transfer will be analyzed.

Jan 1, 1993

By Denis Shishin

The pyrometallurgical production and recycling of non-ferrous metals involves the use of complex feed stocks, having awide range of chemical compositions from sources that include mineral sulphide concentrates, high value obsolete materials and process wastes. The commercial viabilities of these operations hinge on the ability to extract value from these materials. Increasingly, modern computer-based tools are used to describe and predict process outcomes, including mass and heat balances, the partitioning of elements and phase equilibria. At the heart of these predictive tools are thermodynamic databases that describe the fundamental chemical properties of a system and all the components present. A comprehensive research program has been established to develop an accurate, self-consistent thermodynamic database describing all gas-slag-matte-metal-speiss-solid phases in the system Cu2O-PbO-ZnO-Al2O3- CaO-MgO-FeO-Fe2O3-SiO2-S-(As-Bi-Sb-Sn-Ag-Au). The database can be used in conjunction with the FactSage computer platform. The accuracy of the database and its application to industrial practice is demonstrated.

By J. Phillip Mackey

A whole new group of non-ferrous pyrometallurgical processes with the ability to utilize tonnage oxygen and capture sulphur dioxide were developed and commercialized over the period 1940s–1980s. Many of these earlier process developments were undertaken with limited knowledge of the process chemistry and influence of key process variables; in many cases, piloting helped provide much new physico-chemical data, but gaps remained. The second generation versions of these technologies of today provide all the primary copper, nickel and lead produced worldwide by pyro-metallurgical smelting. Further, process development has continued and a new generation of copper and lead smelting technologies have also been developed in China since the 1990s. The older reverberatory and blast furnaces have been progressively replaced by the newer technologies—a good example being the introduction in 1992 of the copper IsaSmelt technology at the Mt. Isa smelter in Australia where the former fluid bed roaster and reverberatory furnaces were replaced by a single new smelting unit, together with an acid plant for sulphur dioxide collection. The development of these new technologies was made possible by investment in fundamental and applied research. The lesson for the future is, in order to sustain these improvements, continued investment in research and development capability is required—to do otherwise is to risk obsolescence and lack of competiveness in the world market. Dr. Peter Hayes at The University of Queensland is one of the many researchers and process engineers who have contributed to the fundamental understanding of metallurgical processes over this period of rapid change in technologies. The present paper briefly outlines some of the many contributions Peter Hayes has made to the understanding of kinetics, mechanisms and phase equilibria in metallurgical systems, and metallurgical process development.

By Bryn Harris

Chesbar Resources Inc.1 is developing a nickel-cobalt laterite project in Guatemala, Central America, by applying existing atmospheric chloride technology to a known resource. The tropical laterite project has an inferred resource of 133 million tonnes grading 1.51% nickel, which represents ~20% of Chesbar?s land holdings in Guatemala. Within its boundaries, the Sechol area has a measured resource of 14 million tonnes grading 1.46 % nickel and 0.08% cobalt, and an indicated resource of 23 million tonnes grading 1.34% nickel and 0.08% cobalt. Notwithstanding the impressive overall resource, the company has taken an innovative approach to a laterite project and is concentrating on El Inicio, a high-grade starter pit with five million tonnes grading 2.1% nickel and 0.08 % cobalt. The process flowsheet is based on atmospheric chloride leaching in a slightly acidic magnesium chloride brine, solution purification by recycled magnesia, precipitation of a mixed nickel/cobalt hydroxide intermediate product, and lixiviant regeneration by modified pyrohydrolysis technology. Initial results suggest that >90% of the contained nickel and cobalt in the non-magnetic fraction of the feed can be recovered, with <5% of the iron leaching. A metallurgical scoping study has established preliminary capital and operating costs for a production facility at a proposed rate of 20,000 tonnes per year of nickel as the intermediate mixed hydroxide. A preliminary assessment of producing a magnesium oxide by-product has also been carried out. This paper reports on the current development of the project and highlights the advantages of working in a chloride medium at atmospheric pressure and slightly elevated temperatures.

Jan 1, 2003

By Liow Jong-Leng

A survey of the interactions of large gas bubbles formed from top and bottom injection of gases into melts was carried out. Spherical cap bubbles were found not to produce much splash when they break through the bath free surface except for that formed by plunging of the-spout at its edges. In contrast, the bursting of balloons produces cavities which give rise to liquid jets being ejected from the bath free surface. The position of the balloons relative to the bath free surface is an important parameter in the formation of the liquid jet. It is found that the interactions of multiple bubbles close to the free surface is important in determining the splash behaviour of gas injected systems.

Jan 1, 1996

By S. Abe

An extensive study has been carried out to determine the true cause of floating slimes precipitation which sometimes occurs and badly affects the quality of copper cathodes. Soluhilities of floating slime compounds systematically measured for the ternary system As-Sb-Ri added solely or in combination with conventional copper electrolyte (63°C) and bench scale electrorefining experiments done by varying electrolyte composition, have shown conclusively that the level of Sb(V) ions plays a substantial role in the precipitation mechanism. It was, therefore, speculated that controlling the level of the less soluble S b ( V ) ions below a certain critical level should result in a complete elimination of the undesirable precipitation. This can be easily achieved, for instance, by the addition of a reducing agent such as SO2 gas and the simultaneous employment of a certain type of cheating agent that effectively removes excessive Sb and Bi from the contaminated electrolyte. Long-term pilot testing conducted in line with the above speculation has confirmed the SO2/chelating resin scheme to be industrially very attractive and feasible.

Jan 1, 1987

By L. R. Verney

About 75% of the market economy countries&apos;s supply of cobalt is produced in Central Africa by Zafre and Zambia. Zafre alone accounts for more than 55% and has the resources and capacity to increase output significantly at any time so its dominant position is unlikely to be challenged in the foreseeable future. Other producers from domestic resources are Canada, Australia and South Africa; and Cuba, probably the most important producer outside of the Market Economy countries. Belgium, Norway, France, Japan and Finland produce cobalt from imported materials. While there are "cobalt ores", inMorocco, USA, Canada and the USSR, the mineralisation is complex and cobalt extraction is costly. In ZaPre and Zambia cobalt is a by-product of copper; in Canada, Australia, France, and Cuba it is a by-product of nickel; and in South Africa it is a by-product from the production of Platinum Group Metals. Thus the levels of cobalt production are inevitably related to the production of other primary metals. While some cobalt is produced by predominantly pyrometallurgical methods most of the world&apos;s cobalt is produced hydrometallurgically. The existence of large hydro-electric power plants and the mineralogy of the copper and cobalt concentrates encouraged research and development in Zafre of the recovery of copper and cobalt by electrowinning from sulfate solutions; much pioneering work was carried out, which lead to construction of the two largest copperlcobalt hydrometallurgical plants in the world, at Shituru and Luilu. Similar systems were adopted in Zambia. In Canada high pressure hydrometallurgical processes based on the sulfate system were developed and adopted in Australia, the Philippines, Finland and South Africa. Meanwhile developments in chloride hydrometallurgical extraction of nickel and cobalt lead to its use in the extraction of cobalt in Norway, France and Japan.

Jan 1, 1988

By Filippos Patsiogiannis

Laboratory size (4.5 kg) low carbon steel melts were deoxidized using Al and FeAl (33% Al), with and without synthetic fluxes, in alumina and zirconia crucibles. The dissolved oxygen, total oxygen, soluble aluminum, insoluble aluminum, silicon and carbon contents in the melt were determined as a function of refining time and temperature. It was observed that the reaction between aluminum and oxygen in solution closely follows thermodynamic equilibrium. Silica present in the alumina crucibles was found to be a source of oxygen for the melt, while this was not the case for zirconia crucibles. Reoxidation of the melt occurred through oxygen pick-up from the atmosphere. The extent of this reoxidation was found to be a function of oxygen content of the bath and the slag cover on the surface of the melt. The effectiveness of calcium-aluminate based fluxes in protecting the melt from the reoxidation and in increasing the rate of removal of inclusions was evaluated.

Jan 1, 1992