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By R. G. Robins

Metal separations based on the selective precipitation of phosphates have a potential application in many hydrometallurgical processes. This paper reviews the literature on the solubility of a number of both divalent and trivalent metal phosphates and presents the result of some additional experimental measurements. The systems examined have been modelled to obtain free energy of formation data for the various species. Computer generated solubility diagrams which are described can be useful in predicting a variety of metal separations.

Jan 1, 1991

By J. P. Ibáñez

The uptake of copper from extremely dilute aqueous solutions by alginate in the form of protonated dry alginate beads was investigated. Barium was used to cross link the alginate forming the beads. The effect of various experimental parameters such as pH and metal ions concentration on the uptake of copper were studied. The uptake was strongly dependent on the Cu-bearing solution pH up to a value of 4.5. A removal of 100% o was achieved when the initial concentration of copper was as low as 8.0 mg/L. The maximum uptake, i, e., the loading capacity, was found to be 167 mg of copper per g of beads. The mechanism governing the removal of copper was found to be ion exchange between protons of the alginate beads and cupric ions of the solution. For this ion exchange process a molar ratio, d[H+]/d[Cu2+], of 2.0 was determined. EPMA-EDX analysis of the Cu-loaded beads showed a uniform distribution of the ions throughout the structure of the alginate, regardless the solution pH. This may suggest that this sorbent material is a porous ion exchanger having high permeability and capacity. The uptake of copper and of the heavy metals cadmium and zinc by this sorbent is compared.

Jan 1, 1999

By Vaughan R. Voller

In many high temperature processes involving liquid melts the common practice is to solidify a fraction of the melt adjacent to the containment wall; a practice that can provide protection of the structural components of the process. The position, shape and transient behavior of these so called "skulls" and/or "ledges" are directly dependent on the thermal process conditions. This paper presents a model of a generic ledge process that can predict the steady shape of a ledge. Two numerical implementations are presented and compared: (1) based on a space grid of continuously deforming finite elements (2) based on a conjugate grid of fixed control volumes and deforming boundary elements.

Jan 1, 1996

By P. S. Arthur

The ISASMELT? process is a submerged lance smelting technology operating in smelters in Australia, the USA, Belgium, India, Germany, Malaysia and China. Further plants are under construction in Peru and Zambia. Following the invention of the Sirosmelt lance technology Mount Isa Mines recognised the commercial potential in the novel top blown bath smelting process and embarked on a development program that has lasted more than 25 years. After successful operation of pilot plants and demonstration plants producing copper and lead, Mount Isa Mines decided to license the technology to external companies. Since the purchase of Mount Isa Mines by Xstrata in 2003, Xstrata Technology has assumed responsibility for transferring the technology to ISASMELT? licensees. In the 15 years since the first commercial furnaces started operation plants have been constructed (or are under construction) with a combined annual smelting capacity of more than six million tonnes of concentrates or secondary raw materials. Process development continues on the commercial scale plants at Mount Isa and elsewhere. Many of the improvements implemented by plant operators have been passed on to, and adopted by, other licensees. Exchange of ideas and technical improvements occurs through ad hoc visits to fellow licensee sites and through regular licensee workshops arranged by Xstrata Technology. This paper updates the reader on the status of various ISASMELT? plants either operating or under construction. It highlights the important role that the technology provider?s operational experience plays in ensuring that new smelting plants ramp up quickly to nameplate capacity.

Jan 1, 2006

By Barry T. Kilbourn

A dominant characteristic of many derivatives of the lanthanides is stability at high- temperatures. Combine this with novel solid-state behavior under those conditions and there is the potential for new materials that can not only improve existing applications but also help create new technologies. These property themes will be traced through new uses ranging from efficient energy generation and raw material conversion to control of environmental emissions and temperature measurement. Conducting ceramics, methane conversion catalysts, sulfur oxide capture agents and phosphor hosts will be described. Some categories will account in the future for significant lanthanide consumption whereas others will remain commercially negligible but technologically vital. All uses will illustrate the versatility of those elements inappropriately termed rare.

Jan 1, 1992

By Morimasa Ichida

One of the key factors of stabilized blast furnace operation under the conditions of high productivity and high pulverized coal rate is to enlarge the raceway to reduce the dead man area. With a reduced dead man area, the descent area is enlarged and the central gas flow is maintained at the same time. In this study, raceway furnace experiments were conducted with tuyere velocity and coke strength changed both in hot and cold conditions to measure the coke degradation rate. Using the coke degradation rate measurements, we examined the equivalent relation between the coke strength and tuyere velocity for coke degradation in the raceway. In addition, in this paper, we discuss the increase in tuyere velocity in relation to an increase in coke strength.

Jan 1, 2006

By James J. Reilly

This paper recounts a history of the contribution of Dr. Gary Sandrock to the science and applications of metal hydrides from 1974 to 2006. It includes a bibliography that cites selected publications over the course these years and which constitutes an important public record.

Jan 1, 2006

By W. K. Connor, O&apos

The U.S. Bureau of Mines, in cooperation with the Idaho National Engineering Laboratory (INEL), conducted over 30 hours of melting tests to vitrify simulated low-level radioactive wastes from the INEL Radioactive Waste Management Complex (RWMC). Five separate waste compositions were investigated, each consisting of noncontarninated soil from the RWMC and surrogate materials used to simulate the actual buried wastes. The RWMC soil and five waste compositions were melted in a 50-lb, single-phase electric arc furnace with a water-cooled shell. These tests were conducted to determine melting parameters in preparation for a large-scale melting campaign to be conducted in the Bureau's 1-metric ton (mt), water-cooled-wall, 3-phase electric arc fumace. Bulk chemical composition was determined for each of the feed materials and for the slag, metal, fume solids, and offgas furnace products, and distributions were calculated for the key elements. The material balance for the furnace operation indicates that from 63 to 84 pct of the feed reported to the slag. Cerium, used as the surrogate for the radionuclides in the wastes, demonstrated an extremely strong affinity for the slag product. Although slag temperatures as low as 1250° C were recorded when melting the RWMC soil, temperatures in excess of 1600° C were necessary to achieve the fluidity required for a successful slag tap.

Jan 1, 1994

By Xiangru Chen, Qijie Zhai, Haicheng Li, Chao Yang, Zhang Wei

The Nb-rich phase generated by the addition of trace amounts of Nb(<0.1wt%) \ and the effects of different content of Nb on the morphology and distribution of graphite in ductile iron were studied in this paper. The results showed that when the content of niobium less than 0.1wt%, the two-dimensional morphology of Nb-rich phase existed in microalloyed ductile iron were mainly regular pattern such as square, triangle, polygon etc. Besides, Nb-rich phase in large size distributed in the matrix with a certain distance from graphite. With the increasing amount of niobium, the dispersion degree of graphite diameter, average diameter and roundness increased slightly, and the number of graphite decreased slightly.

Jan 1, 2015

By S. S. Bogomolov

The relationship between the magnetic properties and micro- structures of Pr-Fe alloys rapidly quenched by melt-spinning and highly undercooled by containerless processing in the Cambridge drop-tube was studied. The maximum measured coercivity, Hc, of as-cast samples was 4450 Oe for Pr-2 wt.%Fe. However, rapid quenching or melt undercooling decreases coercivity for hypo- eutectic alloys (<10 wt.%Fe) and increases Hc for hyper-eutectic systems.

Jan 1, 1992

By Lucas Barbosa de Souza Martins, Frederico Muylaert Margem, Nathalia Carneiro Garcia Rosa, Sergio Neves Monteiro

"A natural banana fiber extracted from the plant pseudostem has shown values of density and mechanical strength with potential for uses in engineering applications such as automobile interior parts and floating components. Moreover, natural fibers can also be used as insulating materials in packaging and building panels. In this case some thermal properties are required. Therefore, the objective of this work was to evaluate the thermal behavior of the banana fiber by means of TGA, DTG and DSC analysis. The TGA curves revealed weight loss related to release of humidity and molecular structure decomposition. Peaks in the DTG curves indicated two intervals in temperature associated with different decomposition processes. The only endothermic DSC peak found was attributed to the lignocellulosic water of hydration being lost around 121°C.IntroductionIn recent times, environmental aspects related not only to pollution caused by non-degradable synthetic leftovers, specially polymeric wastes, but also to climate changes as a consequence of industrial activities, are motivating the use of natural materials. A particular case is fibrous composites, like the fiber grass composites. These synthetic materials, made from non-renewable polymers, are practically non-degradable and contribute to global warming by the CO2 emission associated with the energy required for the fabrication process. In spite of these environmental shortcomings, fiber materials are essential for the production of many items such as insulating chests, automobile cushion, construction panels, etc. An environmentally correct alternative to replace synthetic fibers composites is the naturally existing ones extracted from plants such as ramie and sisal. These have some environmental advantages of being renewable and degradable, these banana plant provide a negative contribution to C02 emission by absorbing greenhouse gas during the plant life cycle. Banana fibers have been used since long time in simple items such as ropes and rugs. Today they are used in engineering applications related insulation in building panels [2] and finish parts in automobile interior components [3]."

Jan 1, 2012

By J. G. Reid

Nickel is second only to aluminium, of all non-ferrous metals, in energy required to convert the ore to metal. Nickel Laterite ores, which constitute the feed source for approximately 40% of world nickel production, are at a particular disadvantage because of the absence of sulphur, as an energy source, in the ore and because lateritic ores general 1 y are not amenable to beneficiation. The dramatic escalation of oil prices which commenced in 1973 and continued for a decade meant that Nickel Laterite refineries using oil as a primary energy source were placed at a distinct disadvantage relative to refineries utilizing nickel sulphide concentrate feeds. By the late 1970&apos;s the continuing large difference in oil and coal prices caused Greenvale to consider converting certain high oil consuming areas of the refinery to coal. These investigations confirmed that the areas of ore drying and power generation, which together consumed 50% of total Plant oil requirements, could be economically converted from oil to coal firing. Construction of the coal conversion facilities commenced in October 1980 and the first ore drying air heater came on line in August 1981. Construction was completed with the commissioning of the coal fired boiler in June 1982. This paper outlines the additions required to receive and utilize coal in ore drying and power generation and how the changeover was completed with minimal process disruption.

Jan 1, 1988

By C. J. Beyke

The U.S. Bureau of Mines has developed a process for the selective recovery of Pb metal from a mixed Pb-Zn concentrate. The concentrate was leached in recycled H2SiF6 at atmospheric pressure and 95° C with a redox potential of 570 mV (Eh). Eighty-five pct of the Pb was selectively leached from the concentrate while 87 pct of the Zn remained in the residue. Pressure leaching of the concentrate was slightly less successful, with 78 pct of the Pb leaching from the concentrate and 80 pct of the Zn remaining in the residue. Pure Pb metal was successfully electrowon from a purified PbSiF6-H2SiF6 solution with 96 pct current efficiency and 0.69-kW.h/kg energy consumption.

Jan 1, 1991

By C. O. Bounds

The magnetic properties of (NdDy)15Fe78B6 sintered magnets have been evaluated using powder prepared by Inert gas atomization. The atomized powder had a particle size distribution from 1 to approximate 1000 microns. The as atomized powders have been sieved into, coarse, intermediate, and fine fractions; magnetic properties were evaluated for the as produced powder and each fraction. A B, of 11.7 kG, a Hci of 11.0 kOe and a BHmax of 32.5 MGOe was -obtained on a sintered magnet made from the as-atomized powder. The magnet made from coarse powder exhibited a slightly higher B, of 12.1 kG, while that from fine powder showed a decrease in B, to 11.2 kG. Hydrogen decrepitation has been utilized to study its effect on the magnetic properties. Finally, cast ingots with a definite columnar structure have also been used to compare the magnetic properties of magnets of the same nominal, composition but of different alloy preparation process. Hydrogen decrepitation does not appear to improve the magnetic properties of magnets made from thin cast ingots. However, it does show a significant improvement in the Hci of magnets made from the atomized powders. Possible causes for the differences in the magnetic properties on magnets made from each process have been discussed in the paper.

Jan 1, 1992

By F. M. Doyle, K. Sreenivasarao

Copper and cadmium metal has been recovered from dilute (3 X 10-4 mol/dm3 ) chloride solutions by ion flotation with dodecysulfate, followed by electrolysis. This approach should facilitate treatment of effluents too dilute for effective direct electrolysis. . The adsorption density of metal dodecylsulfate complexes on bubble surfaces was estimated from surface, tension data, and compared well with experimentally-observed metal removal kinetics, and ultimate recoveries. Copper and cadmium were recovered by electrolyzing the foamate, using steel wool cathodes and a graphite anode. The stability constants of the copper and cadmium dodecysulfate complexes are estimated, and used to analyze the thermodynamics of electrolysis. Dodecysulfate was unaffected by the electrolysis process, and hence could be recycled to ion flotation. A conceptual flowsheet for an overall effluent-treatment process is presented.

Jan 1, 1997

By Christian Ludwig, Virginie Silberstein, Rizlan Bernier-Latmani, Simona Regenspurg

"Residues from waste incineration (bottom ashes) form large amounts of heavy metal-rich waste. Theoretically, heating and the addition of chloride to the ashes could remove these metals by formation of volatile metal chlorides. The remaining heavy metal-poor ashes could be used, for example, as cement additives. In the proposed process of our study we used bypass dust from the cement industry as chloride additives to the bottom ashes. We aim to determine experimentally the optimal conditions to remove heavy metals from ashes and to simulate this process by thermo- chemical modeling. In our experiment we investigate heavy metal flows by heating of differently composed mixtures of bottoms ash and bypass dust in dependence of different furnace temperatures (500-1200 °C). Furthermore, we investigate the reactivity (leaching characteristic) of the resulting product in order to predict if secondary residues can be landfilled in agreement to Swiss regulations for inert materials.IntroductionThe incineration of garbage is generally considered as the most environmentally friendly method for the reduction of municipal solid waste. This is because, compared to traditional storage of waste on landfills, incineration produces less greenhouse gases and destroys toxic organic compounds. The released exothermic energy can be recuperated and the residues from the combustion chamber (bottom ash) are strongly reduced in volume. However, they still form about 600 kt of waste per year in Switzerland, which needs to be landfilled. However, these residues could be potentially used as construction materials after mechanically recovering ferrous and non-ferrous metals. However, the resulting ashes (discharged dry or wet) still contain increased amount of heavy metals (exceeding state regulation) requiring them to be finally deposed on a hazardous waste site. A thermal treatment of these ashes could enable both, to separate and recuperate the remaining heavy metals and an inorganic heavy-metal poor material. The evaporation of metals depends on temperature and can be lowered by addition of chlorides, which would lower the boiling point of most metals by formation of metal chlorides (table 1). 745"

Jan 1, 2008

By Christian Ludwig, Virginie Silberstein, Rizlan Bernier-Latmani, Simona Regenspurg

"Residues from waste incineration (bottom ashes) form large amounts of heavy metal-rich waste. Theoretically, heating and the addition of chloride to the ashes could remove these metals by formation of volatile metal chlorides. The remaining heavy metal-poor ashes could be used, for example, as cement additives. In the proposed process of our study we used bypass dust from the cement industry as chloride additives to the bottom ashes. We aim to determine experimentally the optimal conditions to remove heavy metals from ashes and to simulate this process by thermo- chemical modeling. In our experiment we investigate heavy metal flows by heating of differently composed mixtures of bottoms ash and bypass dust in dependence of different furnace temperatures (500-1200 °C). Furthermore, we investigate the reactivity (leaching characteristic) of the resulting product in order to predict if secondary residues can be landfilled in agreement to Swiss regulations for inert materials.IntroductionThe incineration of garbage is generally considered as the most environmentally friendly method for the reduction of municipal solid waste. This is because, compared to traditional storage of waste on landfills, incineration produces less greenhouse gases and destroys toxic organic compounds. The released exothermic energy can be recuperated and the residues from the combustion chamber (bottom ash) are strongly reduced in volume. However, they still form about 600 kt of waste per year in Switzerland, which needs to be landfilled. However, these residues could be potentially used as construction materials after mechanically recovering ferrous and non-ferrous metals. However, the resulting ashes (discharged dry or wet) still contain increased amount of heavy metals (exceeding state regulation) requiring them to be finally deposed on a hazardous waste site. A thermal treatment of these ashes could enable both, to separate and recuperate the remaining heavy metals and an inorganic heavy-metal poor material. The evaporation of metals depends on temperature and can be lowered by addition of chlorides, which would lower the boiling point of most metals by formation of metal chlorides (table 1)."

Jan 1, 2008

By N. Choi

The distribution behavior of cobalt, gold, and silver in nickel sulfide smelting was investigated between 1250-1300 °C under inert gas atmosphere. The distribution coefficients of these elements between nickel-copper-iron matte and silica-saturated iron silicate slag were determined as a function of matte and slag compositions. The effect of slag additives such as CaO, MgO, and Al2O3 on the solubility of cobalt, gold, and silver in slag was also investigated. It was observed that the distribution coefficients of these &nor elements were strongly dependent on matte grade. For cobalt and silver, the distribution coefficients decreased as the matte grade increased. However, the distribution coefficients of gold increased as the matte grade increased. The solubility of these minor elements in iron silicate slag was considerably decreased by the addition of basic oxides. Temperature dependence of the distribution of the minor elements will also be discussed.

Jan 1, 1995

By Y. K. Rao

The direct reduction of lead sulfide with carbon in the presence of lime was investigated at several temperatures and under two different inert gas atmospheres. The catalyzed reduction kinetics were determined both with a nitrogen atmosphere and a helium-rich helium-nitrogen atmosphere. The reduction kinetics under the latter were d-ecidedly superior to those under the former. The differences-were interpreted in terms of faster diffusion rates in a helium medium and-synergistic effects.

Jan 1, 1983

By B. Boryczko, J. Norwisz, Jose Escobedo Bocardo, Z. Kolenda, A. Holda

"Classical thermodynamic analysis of any thermal and chemical process is usually based on the first law of thermodynamics. Such an approach is not sufficient when deeper understanding of the nature of each elementary process is required. The use of the first and second law of thermodynamics together is necessary to solve practical process more effectively. Enthalpy and exergy balances allow to enhance our understanding of thermal processes especially when cumulative consumption of energy and exergy is calculated. To ensure reliability of such an analysis the least squares method for adjustment of mass balances of principal chemical elements has been applied and described in detail. Numerical analysis has been carried out to compare two different processes of copper production – shaft furnace and flash smelting.IntroductionClassical thermodynamic analysis of any technological process is usually based on the First Law of Thermodynamics in the form of energy (enthalpy) balances. Such an approach is useful in engineering practice as it makes analysis easier in the global scale neglecting modeling of the elementary processes, allows calculation of the thermal efficiency and makes possible to control quality of the measurement results. Additionally, graphical presentation of the energy balance is simple in the form of Sankey diagram.In the case of aluminum electrolysis process, design of the new electrolyzer or its modernization is always based on the enthalpy balance.However, deeper thermodynamic analysis leads to the conclusion that such an approach is not sufficient. The First Law of Thermodynamics guarantees the exact equivalence of the various forms of energy (allowing all forms to be measured in the common unit such as joules) but it does not guarantee interconversibility. Thermal energy (heat) is in a peculiar and unique position, for whereas all other forms can be completely converted into thermal energy, the reverse process id impossible, only a portion of the heat can be converted into mechanical energy. Explanation comes from application of exergy balances. As we know exergy expresses the amount of mechanical work necessary to produce a material in its specified state from components common in the natural environment, in a reversible way, heat being exchanged only with environment [1]. Consumption of exergy connected with the fabrication of some considered product appears not only in the plant manufacturing the product, but also in all plants delivering raw materials for the final production process"

Jan 1, 2008