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By J. C. Agarwal

Rare earth metal alloys are becoming increasingly important, particularly those of neodymium, because of their magnetic properties. This paper will present a generalized approach to the production economics of the metallic rare earth alloys. With appropriate regard for the chemistry of different rare earths and the large impact of economies of scale, it is possible to make fairly accurate estimates of the production costs of other rare earth alloys as well.

Jan 1, 1989

By Pradip

The selective adsorption of chemisorbing fatty acids at high temperatures together with the addition of soda ash and lignin sulfonate as depressants is the key to the industrial processing of bastnaesite ores. This paper presents the results of a fundamental investigation that indicate that alkyl hydroxamates can be an alternative collector for the beneficiation of bastnaesite ores that contain barite and calcite as the principal gangue minerals. The primary mechanism for providing sites for the chemisorption of hydroxamate on bastnaesite appears to be through dissolution of cations, formation of the respective hydroxo complexes and readsorption at the interface.

Jan 1, 1989

By T. Xin

A vertical grain boundary intercepting a horizontal free surface forms a groove to reduce the combined surface energy of the system. We study grooving by surface diffusion with anisotropic surface energy. A recently developed delta-function model of facets is used to describe the surface energy with three or four fold symmetry. It is found that the groove grows following a similarity law. The self-similar groove profile is solved numerically by a shooting method. Even with strong anisotropy, the groove profile can be smooth if the exposed surface orientations do not include a facet orientation. The smooth self-similar groove shape is the same as an isotropic groove, but the size is reduced by a factor that depends on the degree of anisotropy. This induces a large error on the value of surface diffusivity if the isotropic model is used for an anisotropic system. In this talk. we will describe how to correct for this error.1 I Xin, T. and H. Wong, "Grain-Boundary Grooving by Surface Diffusion with Strong Surface Energy Anisotropy," Acta Materialia 51, 2305-2317 (2003). Keynotes: Grain growth, Surface Diffusion, Surface energy, Anisotropy

Jan 1, 2003

By K. Osseo-Asare

Rate laws for the hydrogen reduction of metal ions are typically of the form: [r = -d[M(II)]/dt = k[M(II)]xPy2H] where k is an apparent rate constant, [M(II)] and PH2 represent dissolved metal concentration and hydrogen pressure respectively, while x = 0 - 1 and y = 0.5 - 2. Half-order dependences have been reported for some M(II)/H2 systems; however, no satisfactory explanations have been offered. In an effort to bridge this gap in our understanding, the published precipitation rate data (for M(II) = Cu(II), Ni(II), and Co(II)) are reviewed (with emphasis on the reported reaction orders) and compared with the corresponding but limited electrochemical polarization data. Based on the available literature on the electrochemical kinetics of the M/M(II) and H2/H+ systems it is demonstrated theoretically that, under certain conditions (e.g., in the presence of electron-conducting solids), the rate of the M(II)/H2 reaction can be expressed as: [-d[M2+]/dt = k[M2+]2/1P2/12H] It is concluded that electrochemical processes probably play an important role in the hydrogen reduction of metal ions, especially for systems that involve heterogeneous catalysis.

Jan 1, 2003

By Songlin Zhang

"The McCoy/Cove mine, located in Eureka-Battle Mountain trend of Nevada, is a gold and silver deposit. Case studies of recoverable reserve estimation for gold and silver were made using multiple indicator kriging and volume variance correction. The grade tonnage distributions of recoverable reserves were constructed and compared with the distributions defined by blast hole assays. Optimal pits were generated by Whittle 4D pit optimization package to analyze the impact of different processing recoveries at different economic cutoffs. The results were compared with ordinary kriging. The study indicates that the proposed method for multi-mineral recoverable reserve estimation is more accurate than kriging in tenns of grade and tonnage. The method of using recoverable reserves for pit optimization will maximize global reserve recovery and revenue, and is more efficient than condition simulation regarding computing power.ABSTRACT ONLY"

Jan 1, 1997

By Pinakin Chaubal

An analysis of the blast furnace and the low-pressure shaft DR furnace is carried out by redefining the reaction zones. The concept of a characteristic reaction gas temperature (CRGT) is introduced and the two reactors are compared and contrasted using some recent process developments with an aim to develop a platform for further synergistic innovations.

Jan 1, 2006

By Fatma Arslan

Alada (Kayseri-Turkey) lead-zinc sulfide-oxide ores contain 10.17% Pb, 10.98 %Zn, 164 g/t Cd and 57 g/t Ag. During the laboratory scale flotation tests of these ores, it was found that almost all zinc was remained in the tailings that contain 12.31% Zn, 1.35%Pb, 198.3 g/t Cd, and 22.3%Fe. Three different methods were studied such as basic (NaOH) leaching, roasting+acidic (H2SO4) leaching and direct acidic (H2SO4) leaching for recovering metals that these tailings contain. In the direct acidic leaching, which gave the best results, dissolution efficiencies of 91.5% zinc, 78.2% cadmium, and 14.3% iron were reached at the optimum leaching conditions while Pb remained in the leach residues and the acid consumption was 422.3 kg/ton of tailings.

Jan 1, 2006

By G. J. Shiflet

This paper will review work done in our laboratory on the formation, thermodynamics and crystallization of aluminum based metallic glass with the addition of rare earth elements. The results demonstrate that the metallic glasses are truly amorphous and not microcrystalline and that they are unusual in their formation because the alloys contain 90 at. % aluminum and there is no deep eutectic present in the phase diagram. Tensile strengths that exceed 900 MPa are obtained for several of the compositions and exceed 1000 MPa after partial crystallization.

Jan 1, 1992

By Christian Hecker

An Eh-pH electrochemical sensor developed for on-line pH and redox potentials copper sulphide flotation process control was studied. The electrochemical sensor cell includes two metallic platinum electrodes, a metallic antimony electrode and a high impedance reference cell which are polarized with a potentiostat. For pH and redox potential determinations, the Sb and platinum electrode potentials are measured, respectively, against the polarized electrochemical reference system. The behaviour of this electrode configuration has been investigated in a laboratory scale. An electrochemical sensor device has been succesfully installed and checked in El Teninte Colon Concentrator's SAG line feeding the copper flotation rougher circuit.

Jan 1, 1999

By Chang-hong Peng

Solubility phase equilibrium in the ternary system of Me2+-NH4+-SO42--H2O (Me2+ represented Mn2+, Zn2+ and Fe2+) was studied by the isothermal method at 298K and physicochemical properties of the saturated solution such as density, refractive index and pH were also investigated. The experimental results show that the solubility isothermal phase diagrams of these systems consist of three invariant branches, two invariant points and three crystallization fields. Corresponding to the three crystallization fields, there have three phases of solid, that is MeSO4?nH2O, (NH4)2SO4 and (NH4)2Me(SO4)2?6H2O, respectively. At the eutectic point, the concentration and the refractive indexes of the saturated solution change evidently. Otherwise, the pH value change slowly in all the systems. The calculated results of the density and refractive index agree with the experimental results.

Jan 1, 2006

By Larry Southwick

This paper covers technical and other developments during the first 20 years of Peirce-Smith converting. There were numerous mechanical and process ideas and concepts already being developed and used by others that had possible application within the converter that Peirce and Smith were moving ahead with. There were also other converter configurations in which the basic lining and larger size concepts could function. Finally, as awards and honors began to accumulate, there were those who felt that contributions of other early workers were being ignored. The working out of these conflicts and differing directions will be described.

Jan 1, 2009

By Todd S. Fayram

The Gordonsville Operation of Pasminco US Inc. along with the Center for Advanced Mineral and Metallurgical Processing (CAMP) at Montana Tech studied, developed and implemented a pilot scale hydrometallurgical facility for the industrial recovery of germanium and gallium. This paper describes the joint testing and engineering program that culminated in this successful process.

Jan 1, 2003

By M. A. Llavona

The study of the formation and components of copper patina and its conservation has assumed great importance. The changing environment has accelerated the processes of patinas degradation; thus, the exhaustive study of factors capable of affecting the patina formation, growth and durability has assumed great importance for the industrial activity of copper. The main components of the patina, oxides, chlorides, nitrates and sulfates, have been determined; the effect of physical, chemical and microbiological factors on patina formation, particularly the influence of acid rain, natural organic matter, particles and microorganisms have been defined. The effect of different electrolytic solutions that accelerate the formation of copper patinas has been determined, and a review of the state of knowledge of the formation and evolution of metal patinas has been made.

Jan 1, 1999

By Peter J. Hancock

The pyrometallurgical .processing of non-ferrous, complex materials and wastes will be surveyed. Pyrometallurgy offers the most versatile way of processing a large variety of such materials because of its high temperatures, closely-controlled oxidation potential and the availability of commercially-proven reactor configurations. Some current industrial applications will be reviewed and possible new applications as well as future trends will be outlined.

Jan 1, 1994

By T. J. Weitz, J. E. Micheletti

"Pegasus Gold's Beal Mountain Mine is located near the Continental Divide, SW Montana. Conventional surface mining utilizes crushing, heap-leaching, carbon absorption/desorption, electrowinning and refining to produce approximately 60,000 oz gold annually. A leach pad sits at 2,300 meters (7,500 ft) elevation. Winters are long and cold with average snow accumulations ofl-2 meters; temperatures fall below minus 40'C and wind chill temperatures below 70°C. The Beal Mountain staff has developed special tools and procedures for burying drip emitter lines, and managing the heap and process solutions to allow for uninterrupted gold recovery during the winter season. Management of water balance and spring runoff is critical to the operations' success, due to mountainous terrain, high precipitation and proximity to a fishery and elk herd. The mine has an extensive network of land application disposal (LAD) and stormwater control systems to assure environmental protection and regulatory compliance.ABSTRACT ONLY"

Jan 1, 1997

By Mark F. Vancas

Virtually every new process plant project goes through the ?Feasibility Study? phase before actually being built. The Feasibility Study is used by the owners and the bankers to evaluate the economics of the project and determine whether or not the proposed investment meets their respective investment guidelines. With a positive result, the project is approved and goes to construction and operation. Then, the actual costs are incurred and these actual costs may or may not agree with what the Feasibility Study predicted. Just how good have Feasibility Studies been? This paper looks at various projects and compares predicted to actual results and also gives information on how to spot a poor feasibility study.

Jan 1, 2003

By Ali Unal, Ali I. Kahveci

Alcoa developed a fractional crystallization process some 30 years ago as a method to purify aluminum. Depending on the purity of feed metal, it has been commercially used to make 3N7-6N purity aluminum. As an extension of this technology, Alcoa has experimented with purifying various aluminum alloy scrap for the purpose of recycling. Purified aluminum alloy scrap can be reused for making the same alloy. This presentation will discuss Alcoa fractional crystallization technology and its application to alloy scrap processing. Process capabilities and the partitioning of eutectic and peritectic impurities during fractional crystallization will be discussed for the alloy systems investigated.

Jan 1, 2000

By Robert F. Jenkins, King G. Robertson

This paper presents a practical approach for utilizing a computer model to determine the mass balance for a typical UBC recycling complex - starting with raw materials input, through scrap preparation, delacquering, melting, alloy adjustment and casting. This model is especially concerned with metal unit losses throughout the recycling complex with emphasis on metal losses at the melting furnace. The model also addresses the application of hardener alloys, metallurgical salts, chlorine for demagging, and reagents for acid gas emissions control. Other issues addressed are dross generation, acid gas emissions and dirt and fines to landfill. One benefit of the model is the conversion of annual production objectives to hourly production rates and resource requirements taking into account production schedules, maintenance downtime, and operations inefficiencies.

Jan 1, 2000

By Mark E. Schlesinger

A substantial database exists for the thermodynamic properties of many antimonide compounds, but these have rarely been compiled or critically discussed. An abbreviated version of a full?scale review of the thermodynamic properties of binary antimonide compounds is presented, focusing on the choice of experimental techniques.

Jan 1, 2006

By Wenshan Zhang

This paper described the present status of China electrolytic manganese industrial production. Electrochemical reactions on cathode and anode, the major technological process, technical requirements on the production and technical index and quality control of the products and the ways of increasing current efficiency during Manganese electrolytic process have been expatiated.

Jan 1, 2006