Search Documents

By Shigeo Asai

"Electromagnetic processing of materials is newly proposed to be considered as one of the engineering fields where functions of electromagnetism are utilized for processing electrically conducting materials, such as liquid metals, electrolytes and plasmas. The background requiring this processing and the engineering characteristics supporting it are described. The applicable functions of electromagnetism to material processing are revealed from the view point of magnetohydrodynamics. The existing processes and the proposed ones are classified into utilized functions and engineering applications are discussed. IntroductionElectric energy has been used in the metallurgical field for the processes of melting, refining and solidification. In these cases both the magnetic field which is induced by an imposed electric current, and the electric current are applied on electrically conducting materials such as molten metals. Thus, it turns out that the magnetohydrodynamic (MHD) phenomena have unconsciously been seen in metallurgical processes using electric current. The academic backbone studying MHD phenomena is the Magnetohydrodynamics which is being developed in the fields of plasma physics, astrophysics, fusion research and nuclear energy.The first attempt where magnetohydrodynamics was intentionally applied on metallurgy was a Symposium of IUTAM (The International Union of Theoretical and Applied Mechanics) in titled as ""Metallurgical Applications of Magnetohydrodynamics"" at Cambridge, UK, 1982 [1]. This timely event stimulated a few metallurgists to recognize the importance of ~MHD and was a good warning to the metal societies in the world. Especially in Japan, the Steelmaking Investigative Subcommittee of Research Planning Committee in the ISIJ (The Iron and Steel Institute of Japan) discussed the application of ~IHD to metallurgy and selected it as one of the four major innovative subjects for future steelmaking technology in Japan [2]. Indeed, the term of ""Electromagnetic Metallurgy"" itself was firstly coined by this subcommittee. Upon the request of a report from the subcommittee, the ISIJ has established a committee on ""Electromagnetic Metallurgy"" at 1985, under the author's chairmanship."

Jan 1, 1988

By Rudolf Keller

"EMEC Consultants is developing a process to extract oxygen, aluminum and silicon from lunar anorthositic soil. The process will provide oxygen in space for propulsion, aluminum as a structural material, and possibly silicon for the construction of solar cells.The evolution of the process concept in the course of our present NASA-sponsored SBIR effort is discussed. A molten salt electrolysis producing aluminum and oxygen is the central step; inert anode technology is to be employed. Silicon will be produced by reducing the anorthite, CaAI2Si20S' with aluminum. In a steady-state operation, all components of the ore added have to be removed from the process, and the removal of calcium is a major topic of our experimental studies.Utilization of Lunar ResourcesUtilization of lunar resources may play an essential role in the exploration of the solar system and the conquest of space. High costs are involved in overcoming Earth's gravity to supply missions in space. Even at a low projected cost of $ 300 for transporting a pound of payload into Earth orbit -- today's costs are many times higher -- it appears attractive to use resources in space to produce needed materials. Processing of lunar resources on the lunar surface is an obvious possibility.Oxygen is a product of major interest. It is required for support of human life in space. Even greater quantities may be needed for propulsion, to conduct further missions into space. To satisfy this demand for oxygen through lunar processing requires a quite different solution than to supply oxygen on Earth, where oxygen gas is abundant and easy to extract from air or water. On the lunar surface, solid oxide materials have to be used. Hydrogen reduction of ilmenite and subsequent electrolysis of the resulting water is being studied [1]. Other suggestions include fluorination of lunar soil [2], reduction with lithium and electrolytic decomposition of the resulting lithium oxide [3], and aqueous HF leaching [4]."

Jan 1, 1988

By James C. Barker

Recent investigations of a 55-km long trend of intrusive complexes on southern Prince of Wales Island have identified significant resources of Nb, Y, REE. U, Zr, and a host of potential by-product metals. The northwesterly trend comprises multi-phased sodic alkaline and peralkaline diorite, monzonite, syenite, and riebeckite granite. There are at least three significant deposit types recognized, two of which, 1) pegmatite dikes/vein-dikes that zone laterally from the intrusions and 2) concentrically zoned pegmatites, contain most of the lithophile metals. A third, epigenetic replacement-type mineralization, contains much of the U resource. Other deposit types with minor or unknown resource potential include diatremes, carbonatite, and placers. This report summarizes the deposit evaluations, characterizes the mineralization, and estimates the resources. To date a total of 40.7 million tons of mineralized material is estimated as indicated or inferred. Most of the Y203 plus REO is at a grade exceeding 0.5% and half of the Nb20S exceeds 0.125%. Tonnage estimates would likely be substantially lncreased with additional exploration. Mineralogy is generally fine-grained and complex, and consists of more than a dozen principal REE-Y-Nb-U-Th-Zr phases, the sum of which may compose up to half of the rock. Approximately half of the REE-Y content comprises the heavy yttrium subgroup which is uncommon compared to deposits elsewhere. Although the Alaskan deposits are likely subeconomic at today's metal prices and consumption levels. recent technological advances suggest future demand may increase.

Jan 1, 1988

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 I. Iwasaki

Flotation characteristics of pyrrhotite by itself and in complex sulfide ores are reviewed with respect to the effects of oxidation, grinding media and other electroactive minerals.

Jan 1, 1988

By Susanne Pignolet-Brandom

QEM*SEM is an automated scanning electron microscope/computer system that characterizes samples with regard to mineral modal abundances, mineral grain and particle sizes, mineral associations, and particle surface areas. Additional information, based on the classification of particles according to the area percentage of a mineral of interest, can be obtained for samples of particulates. QEM*SEM is capable of analyzing a wide variety of materials although it was originally developed for applications to the minerals industry.

Jan 1, 1988

By David M. Davidson

Seven intrusive phases have been mapped to date in the 1 b.y. Red Bluff Granite Complex (RBGC) near El Paso, Texas. This batholith is 20 km2 in area and intrudes older supracrustal units as well as a trachyte ignimbrite cap. Two early microgranite sills are spatially separated 6 km from a porphyritic, three-phase "ring complex" by a tin-bearing, biotite granite which cores the RBGC. These units are intruded, in turn, by a riebeckite granite which locally exhibits lineated and pegmatitic textures as well as exceptionally high light REE and Zr values (800 ppm La; 3,000 ppm Zr). The riebeckite granite is exposed in three separate occurrences within the Franklin Mountains. REE values in the RBGC are depleted in HREE and show distinct negative Eu anomalies. Typical La/Yb ratios are 5:1-2:1 with Eu values ranging from 10-80 ppm. The mineral source of the high REE values in the riebeckite granite has not yet been specifically identified, but is believed to be zircon.

Jan 1, 1988

By L. G. Wiseman

The raw materials processed, highlights of technology used, and products produced at INCO's Copper Cliff Nickel Refinery in Ontario, Canada, are described in this paper. INCO's Bessemer matte separation process yields various nickel and copper products and intermediates. The latter presents the main supply of raw materials for the Refinery. Key features in the Refinery are Top Blown Rotary Converters and the INCO Pressure Carbonyl (IPC) process. Process improvements made since the commissioning of the Refinery in 1973 are also discussed. The Refinery produces a variety of nickel products, including nickel powders. Residue after carbonylation presents an important intermediate enriched in precious metals and cobalt that serves as feed to downstream operations for recovery of the residue's metal values. Also discussed are detection, measurement and control procedures which ensure safe operation.

Jan 1, 1988

By Roger Agnew

Sulphide ores mined by Inco Limited in the Sudbury District contain small quantities of cobalt. During beneficiation, cobalt distribution to various streams is similar to nickel. After smelting, nickel is selectively extracted by carbonyl refining and the cobalt remains in the carbonylation residue. This residue is processed in a specialized hydrometallurgical plant to produce precious metal residues, copper cathodes, and a nickel- cobalt carbonate intermediate product. The nickel-cobalt is shipped to Port Colborne where the cobalt is separated as cobaltic hydroxide and refined to metallic cobalt. This paper deals specifically with the recently constructed Electro Cobalt Refinery. The cobaltic hydroxide is dissolved and residual zinc, copper and nickel are removed by ion exchange and organics by a carbon column. The purified cobalt solution is fed to the electrowinning circuit where cobalt rounds are produced on stainless steel mandrels. In the design and construction of the refinery, special attention was directed to materials of construction both for the process equipment and the physical plant, operating control and flexibility, and the quality of the working environment. The end result is an efficient and clean operation which yields a product of excellent quality.

Jan 1, 1988

By P. M. Tyroler

At INCO's Copper Cliff Nickel Refinery, nickel is extracted by using the INCO Pressure Carbonyl (IPC) process. The resulting IPC residue containing copper, nickel, cobalt, iron, sulphur, precious metals, selenium and tellurium is further processed at a hydrometallurgical plant. This plant treats approximately fifty metric tons per day of IPC residue. The components of the feed are separated in a number of steps and a precious metals concentrate, nickel-cobalt carbonate, a selenium-tellurium intermediate and copper cathodes are produced. An iron-arsenic waste stream is also produced and discarded to tailings. The hydrometallurgical processes include pres- sure leaching, cementation, precipitation, thickening, filtration and electrowinning. This paper describes in detail the individual steps of the flowsheet.

Jan 1, 1988

By Forsén. O.

In this ?paper practical solidification of anodes containing nickel, arsenic, antimony and bismuth is compared with the equilibrium? diagrams and kinetic ?factors. In order to clarify the distribution of the impurity elements in the anode the structures were studied after the solidification and also after the electrolysis of anodes. This examination was carried out with optical microscope, scanning electron microscope and electrochemical measurements. All the nickel is remaining metallic in the copper matrix during the solidification and therefore nickel is dissolved in the electrolysis at all oxygen contents, when the nickel content is 0.25 wt-% or less in the anode. The practical .solidification mechanism of the anodes, when the nickel content exceeds 0.25 wt-%, proceeds by the crystallization of nickel oxides. In oxygen containing copper anodes nickel oxide is verified to crystallize together with antimony in certain conditions and to form a micaceous compound (3Cu2O?4NiO?Sb2O5), which may build up a very harmful floating slime in the electrolyte. Arsenic is strongly enriched along the phase boundaries in oxygen free copper anodes. An intermetallic compound Cu3As is formed when the amount of arsenic in the anode. exceeds 0.7 wt-%. This compound is more noble than the copper matrix. This means 'that a selective dissolution of copper-arsenic compounds takes place. The copper matrix dissolves more strongly than the grain boundaries. The solidification structures of oxygen free bismuth containing copper anodes show clearly the influence of bismuth. Thin bismuth films which are less .noble than the metallic copper matrix, are formed during the solid1ficatton process. As a result of this the?grain boundaries are dissolved faster than the copper matrix.

Jan 1, 1987

By Richard D. Hagni

Ore microscopy is a useful technique to detect and study the ore minerals that are associated with sediment-hosted and volcanic-hosted deposits of finely disseminated gold and silver. Ore microscopy can be used to determine the: 1) precious metal-bearing minerals in some ores, 2) associated ore minerals that may form geochemical exploration halos, 3) character of iron sulfide grains, 4) extent of sulfide oxidation, 5) character of oxidized iron minerals, 6) character of original sulfide grains from a study of the hypogene and supergene oxidized ores, 7) relative time of oxidation, 8) character of organic matter, 9) minerals that may consume excessive amounts of cyanide solution, 10) extent of silicification and silica encapsulation, and 11) possibility of salting.

Jan 1, 1987

By J. H. Puffer

The copper mineralization of the Mesozoic Passaic Formation of New Jersey is typical of copper deposits in eastern North American Mesozoic sediments. Most such deposits are located at the base of the first of several basalt flows that are interbedded with continental, red-bed sediments. The copper mineralization is similar in most respects to that of the Keweenawan Basalts of the Lake Superior area. The first basaltic flow units of the eastern North American Mesozoic basins, and the Keweenawan Basalts, are continental quartz tholeiites of similar chemical composition and copper contents. The copper minerals and associated zeolite facies metamorphic mineral assemblages of these two rock units are also approximately the same. Stoiber and Davidson (1959) suggested that Keweenawan copper was mobilized and concentrated during metamorphism. The evidence pertaining to the Mesozoic copper deposits of New Jersey is consistent with such an interpretation and also with DeVore's (1955) suggestion that ore fluids commonly arise as a result of the mobility of metals under metamorphic conditions. There is additional evidence that final metamorphic concentration of Mesozoic copper was preceded by an initial stage of hydrothermal precipitation related to fluids emitted by basaltic magma.

Jan 1, 1987

By E. C. T. Chao

Micro-optical and synchrotron radiation-induced X-ray fluorescence (SXRF) techniques have been used to study unoxidized and oxidized samples of Carlintype sedimentar,y rock-hosted disseminated gold ore. In these samples, Where much of the gold is submicroscopic, the SXRF technique, which has a spatial resolution of about 20 ~m and a minimum detection limit (MDL) in the ppm range, is an ideal and necessary tool for precisely locating gold-rich areas in a sample. Gold-rich areas pinpointed by SXRF were later studied in detail by micro-optical methods, principally optical microscopy and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). In two unoxidized and one oxidized ore samples, SXRF analyses have shown gold to be present predominantly in discrete clay-rich and silicified areas. Gold was not detected by SXRF in association with pyrite or carbonaceous materials. SEM-EDX examination of the gold-bearing areas in the unoxidized samples succeeded in identifying only two free gold particles, 0.2 and 0.5 ~m in size. In the oxidized sample, gold particles appear to be larger (but still submicroscopic) in average size and more evident in micro-optical examination after SXRF location of goldbearing areas. The findings of these studies may help to improve the efficiency of processing and recovery of gold from unoxidized ores.

Jan 1, 1987

By G. Barbery

The models for particle composition prediction that have been put forward are limited to simple textures and lead to an independance of grade with respect to particle size in broken ore. A presentation is made of a modification in texture description; binary textures, in which each subeonstituent has its own breakage characteristics are introduced. The calibration of the textural model can be made using heavy liquid separation results. The application to the case of coal is presented. Coal washability data present spe¬cial difficulty due to the distribution in the specific gravity of coal, which must be taken into account. Coal s.g. distribution is taken as a generalized exponential distribution. Model calibration is then possible and is shown to be in good agreement with experimental data.

Jan 1, 1987

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 Walter E. Dean

Twenty six samples of carbonaceous gold ores and associated rocks from outcrop and mine localities in northcentral Nevada were analyzed for concentrations of major. minor, and trace elements, total sulfur, and organic carbon. Q-mode factor analysis was used to define six distinctive carbonate, organic, and detrital associations of elements, and to group samples based on these associations. The trace metals that have clearly enriched the organic-carbon-rich samples are V, Zn, Ni, Cu, Cr, and Mo, although few of the samples could be considered "metal-rich" when compared to other organic-carbon-rich black shales. Rock-Eval pyrolysis was used to evaluate thermal maturity and hydrocarbon yield of the samples. Unfortunately, most samples were too thermally altered to be suitable for routine organic geochemical characterization of organic matter. The 813C values of organic carbon in rocks from different deposits have a trimodal distribution, but there is no clear distinction between the three groups of deposits that can be related to age, thermal history, or depositional environment.

Jan 1, 1987

By D. S. Barr

Mineralogical, lithological, and metallurgical studies were conducted on various gold ore deposits currently controlled by Freeport-McMoRan Gold Company. Ore samples were first lithologically and mineralogically categorized, then subjected to chlorination, roasting, and autoclaving pretreatments to determine their effects on gold recovery in a subsequent alkaline cyanide carbon-in-leach extraction. The studies indicate that, while organic carbon and sulfide sulfur are the primary refractory components, their effect on process response must be interpreted with respect to the deposit's geology and mineralogy. This approach has proven to be an effective method for evaluating metallurgical alternatives and fore-casting future mill performance.

Jan 1, 1987

By K. Knuutila

The behaviour of thiourea, animal glue and chloride ions in the electro¬lysis of copper has been investigated by various different electrochemical experiments, i.e. polarization curves with stationary copper electrodes, long-time galvanostatic electrolyses and Hull cell experiments. Polarization curves with stationary copper electrodes show that animal glue has a polarizative effect on the deposition potential. Small thiourea contents affect depolarizatively when high concentrations retard the copper deposition. The microstructures of the deposited copper after the long-time electrolyses show that animal glue favours a basis oriented deposition structure. With thiourea the field orientated structure was evident. It was also observed that the deposited structure depended much on the grain structure of the starter sheet. The chloride ion concentration has a drastic effect on. the crystal size of the deposited copper as it was found out in Hull cell tests. Chloride ions flattened the the crystals and the deposition became smoother when the chloride ions were added. The cathode copper quality is discussed according to the literature. Special attention is paid on the codeposition of thiourea and the origin of sulphur impurities in copper cathodes.

Jan 1, 1987

By T. A. Edison

A distinct hydrocarbon maturation anomaly coincides with the Gold Acres open pit, Nevada (Figure 1). Both atomic hydrogen to carbon (H-C) ratios and reflectance measurements of contained organic matter indicate significantly higher maturity in samples collected within the confines of the open pit than in samples from the surrounding region (not shown in Figure 1).

Jan 1, 1987