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By Corate L. Brierley

Low-grade porphyry copper ores containing chalcopyrite as the primary mineral was leached by two strains of acidophilic, thermophilic microbes belonging to the genus Sulfolobus. Leach tests were conducted in glass columns heated to 60-70° C. Pinto Valley and San Manuel ores sized to -1/2 inch + 50 mesh were effectively leached by the thermophilic organisms, but pinto Valley and Cyprus Bagdad ores sized to -2 inch + 1/2 inch resisted leaching. Aeration did not contribute measurably to bacterial copper extraction, since two columns, one inoculated and one sterilized, having a rest/ leach cycle without recurrent aeration exhibited copper extraction patterns similar to those of the aerated columns. Distilled water can be substituted for 9K medium without diminishing copper extraction. Decreasing the pH of the leachate to about 1.8 enhanced the extraction of copper from pinto Valley ore with the thermophilic microbes. Thiobacillus ferrooxidans was found to be relatively ineffective at copper extraction from pinto Valley ore. Of eleven solvent extraction reagents tested, Adogen 364 and Warsol at concentrations of 0.1% and 0.012 were inhibitory to oxygen uptake by the two Sulfolobus strains. Di-2-ethyhexyl phosphoric acid at concentrations of 0.1%, 0.01% and 0.001% were totally inhibitory to the respiration of both organisms.

Jan 1, 1979

By George A. Snyder

The presence of moderate to high concentrations of colloidal clays in coal preparation plant waters can cause serious operating and economic problems for a coal company. Among the host of possible problems are the following: 1) Poor separation of clays in the plant thickener, resulting in: a) Increased ash in the clean coal. b) Increased specific gravity of the wash water and decreased coal recoveries at the desired quality. c) Increased thickener operating costs in trying to overcome the problem. 2) Decreased solid concentrations in the thickener underflow and increased pumping requirements to meet solids withdrawal requirements.

Jan 1, 1979

By Robert J. Mitchell

A general approach to mine backfill design, including laboratory testing procedures, is outlined in this paper. Relationships between certain design parameters are developed and the effect of other factors is discussed. It is concluded that the inclusion of backfill design calculations at an early stage of mine design can often produce over-all design economies. Not only are the data needed for backfill plant and tailings disposal area design, but also the pillar recovery method and over-all mine stability are dependent on the attainable fill properties.

Jan 1, 1979

By S. L. Crouch

A. C. Dieringt The procedure described by Professor Crouch for the modelling of mining in faulted ground allows the elastic and inelastic deformation to occur simultaneously, that is, fault slip occurs while an element is being mined. The energy release rates (ERR) shown in Crouch's Fig. 10 are apparently calculated from his equation 9 using the i total deformation Din (see the upper load line of Fig. I) Refractories The institute of 'Gesteinsh iittenkunde' of the technical university at Aachen, the Refractories Research Institute at Bonn, and the Verein Deutscher Eisenshiittenleute (VDEh) at Diisseldorf are to hold the XXII International Refractory Colloquium on 27th and 28th September, 1979, at Aachen.

Jan 1, 1979

By J. E. Dutrizac

A pyritic Zn-Pb-Cu ore waspercolation leached with acidified ferric sulphate solutions; zinc and copper were leached, lead was oxidized, but not dissolved, and pyrtte was essentially unattacked. High zinc extractions were achieved after a few months leaching, and substantial zinc solution concentrations could be produced by recycle of the oxidized solution. The leaching rate was generally controlled by the transport of the ferric sulphate oxidant. Zinc extractions increased with increasingferric ion concentration or flow rate, but were essentially independent of the concentrations of sulphuric acid, ferrous sulphate, cupric sulphate or chloride ion. The leaching rates were insensitive to the height of the ore column once a minimum height had been exceeded (0.8-1.0 m). Elemental sulphur was the principal sulphidic reaction product, but variations in the ratio of sulphur to sulphate produced anomalous temperature effects.

Jan 1, 1979

Professor Somasundaran has given an excellent presentation of the numerous problems which remain to be solved before the selective aggregation of fine particulates is likely to see broad commercial application in the beneficiation of mineral fines. However it is useful, I think, to reiterate some of the major problem areas. The over-riding factor which has limited the development of selective aggregation techniques is that processes such as coagulation and flocculation tend to be inherently non-selective. Conditions which favor the aggregation of one kind of fine particles usually favor the aggregation of all kinds of particles. As Professor Somasundaran has pointed out, the state of aggregation of a fine-particle dispersion is primarily determined by the forces of interaction between the individual particles. In most systems, the dominant forces are: 1. van der Waals - London Dispersion forces between the particles themselves 2. electrical double layer forces 3. steric forces between adsorbed layers on the surfaces of the particles. The London Dispersion forces between like particles are always attractive, but for dissimilar particles dispersed in a fluid medium can, in some cases, lead to a net repulsion. Electrical double layer forces always lead to repulsion between like particles but can, again, cause either attraction or repulsion for dissimilar materials. The steric forces, which are by far the least understood of the three types, can also lead to attraction or repulsion depending on condi-

Jan 1, 1979

By Lennart Bergstedt, Olov Fägremo

Boliden Metall Aktiebolag, the prime base metal mining company of Sweden, treats some 10-10.9 t/y (11-12 stpy) of sulphide ore in nine concentrators. During the years considerable effort has been devoted to the development of all phases of the technology of ore prospecting, mining, milling, smelting and refining. This has been necessary due to the complex and low grade ores. The autogenous grinding technique was first studied within the company as early as 1945. Basic test work commenced during the early fifties, whereby the merits of pebble grinding could be evaluated. In parallel with the converting of the rod mill/ball mill grinding systems to rod mill/pebble mill systems, the development work concerning the feasibility of autogenous grinding went on resulting in the installation of a 8 6.7 x 2.1 m (8 22 x 7 ft.) cascade mill at the Vassbo lead mine in 1959. Long term tests at the Vassbo plant together with a number of pilot plant test involving low grade silicious ores and pyritic comples base metal ores successive led to a better understanding of the process of autogenous grinding. Before a two stage autogenous grinding system could be chosen for the expansion of the Aitik copper mine, a carefully planned survey concerning grinding characteristics and variances in the ore and flowsheet was undertaken. The expanded plant went on stream in 1972 and in the beginning of 1973 and since then has performed excellently.

Jan 1, 1979

By A. S. Romaniuk

More than a decade ago, CANMET management recognized the need to make better use of existing technological information in mining and extractive metallurgy-two fields basic to the economic well-being of Canada. There were at that time no indexes or files dedicated to disseminating technical information for the many minerals mined and processed in Canada, including coal. CANMET, with the nation's largest research and library resources in the minerals field, was in a unique position to fill this need. Initial efforts were concentrated on building a mining file, beginning with identification of world sources of published information, development of a special thesaurus of terms for language control and adoption of a manual indexing/retrieval system. By early 1973, this file held 8,300 references, with source, abstract and keywords given for each reference. In mid-1973, operations were computerized. Software for indexing and retrieval by batch mode was written by CANMET staff to utilize the hardware facilities of EMR's Computer Science Centre. The resulting MINTEC file-one of the few files of technological information produced in Canada-is the basis for the national literature search service in mining offered by CANMET. Attention is now focussed on building a sister-file in extractive metallurgy using the system already developed. Published information sources have been identified and a thesaurus of terms is being compiled and tested. The software developed for CANMET's file-building operations has several features, including the selective dissemination of information and production from magnetic tape of photo ready copy for publication, as in a bi-monthly abstracts journal.

Jan 1, 1979

By E. L. Reed

This paper addresses the state and federal permit- ting requirements and regulatory constraints associated with the development of new "grass roots" surface coal mines in the Western United States. Since a major portion of new coal development in the West will be on federally leased coal in Wyoming, my comments are directed towards that geographical area. This will give the reader some insight into the current regulatory framework within which western mining companies must operate-i.e., the major applicable state and federal laws and regulations, the more important state and federal regulatory agencies, and the major construction and operating permits that are required. Before discussing the impact of the regulations on our business, I would like to tell you something of my company and then briefly discuss Exxon's forecast of the long range outlook for coal. Carter Mining is an Won affiliated surface coal mining company. Exxon became interested in the coal business in the mid 1960's with the recognition of the future need for alternative fuel sources. Since that time, it has acquired coal reserves located in Wyoming, Montana, North Dakota, Arkansas, Texas, Illinois and West Virginia. Carter's first surface mine, the Rawhide Mine, located north of Gillette, Wyoming began production in August, 1977. Our second surface mine, Caballo, located just south of Gillette, began operating last October. We have a third block of federally leased coal just east of Gillette. By 1985 we anticipate Carter's western surface mines will be producing at an annual rate of 30 million tons, subject, of course, to successful market development efforts and regulatory considerations. Rawhide will ultimately have a permitted capacity of 24 MM tons per year. The coal at Rawhide is in two seams; one 80 feet in thickness and the other 20 feet (including a 6 to 10 foot parting). A large shovel is used to remove the overburden, and a similar shovel and dragline are used to mine the coal. Caballo has a 75 foot seam; otherwise it is similar in design and operation to the Rawhide Mine.

Jan 1, 1979

This chapter summarizes data on crude mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are tables that show the principal mineral commodities exported from and imported into the United States and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of volume I and in the State chapters of volume n of this edition of the Minerals Yearbook. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in this chapter is what is normally termed "mine output!' It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the production of auxiliary processing at or near the mines.

Jan 1, 1979

By Kerstin Malmqvist

Simulation technique has been used for a feasibility study of a deep exploration project for massive, sulphides in an old mining district, the Skellefte field. An interactive computerized mathematical model of an ore field and a drilling procedure has been constructed. It is possible to represent varying geological structures. The model also takes in consideration economical factors such as drilling costs and ore values. On this model Monte Carlo simulations and probability calculations are done in order to estimate the outcome of different drilling strategies under varying geological assumptions. Under the specific conditions of the well known Skellefte field, it is found to be possible to even calibrate the mathematical model.

Jan 1, 1979

By V. K. Karra

A mathematical model for the performance of a vibrating screen is developed in terms of an oversize partition curve. This is a normalized curve for any assemblage of particles presented for screening when their size is normalized with respect to the 50 per cent passing size (d50 ) under the prevailing screening conditions. Based on the throughfall aperture (hT) of the wire mesh on the deck, the effects of oversize (% >hT), half-size under (% <0.5 hT), deck location and feed rate were evaluated using the existing screen sizing information. All these variables and also the near-mesh (1.25 hTx 0.75 hT) content (%) of the feed affect the d50. Performance data from different decks of a double-deck screen with various feed rates, size distributions and screen apertures were used to evaluate the near-mesh factor. Effects of wet screening and material bulk density are also incorporated in the model. This generalized model is useful for the simulation of a multiple-deck screen. It furnishes the sieve analysis information of all the deck output streams and therefore has a potential use in the over-all circuit evaluation when used in conjunction with relevant crushing and grinding performance models. An example illustrating the prediction capabilities of the model is given.

Jan 1, 1979

A viable mineral economy requires availability of economic deposits, the ability to exploit then, and protection of the public interests. The natural tendency for each party to consider only its legitimate self interests can lead to delays or deadlocks. The paper presents several viewpoints aimed at opening each party&apos;s mind to the ideas of others in the hope that negotiations might be more reasonable and rapid for the benefit of all concerned.

Jan 1, 1979

By Richard G. Sandberg

The Bureau of Mins, U.S. Department of the Interior, is investigating a hydrometallurgical procedure to conserve cobalt, nickel, and copper by recovering the metals from the matte byproducts of smelting Missouri lead ores. For want of adequate processing technology the mattes are now either unmarketable or marginally so. The procedure involves leaching with manganese dioxide and sulfuric acid to obtain copper, nickel, cobalt, lead, and manganese sulfates, and elemental sulfur as expressed by the following reaction: MS + MnO2 + 2H2SO4 ? MSO4 + MnS04 + S° + 2H2O, where M = Cu, Ni, Co, and Pb. The leach solutions, containing near theoretical amounts of sulfuric acid and manganese dioxide at 85° to 100° C, convert up to 98 pct of the cobalt, nickel, and copper in the mattes to sulfates in less than 2 hr. As they are formed, the cobalt, nickel, and copper sulfates are dissolved leaving a residue of lead sulfate, lead, sulfur, and gangue. The soluble metals are recovered from the leach solutions by caustic and sulfide precipitation, and the residue returned to the smelter for lead recovery. The manganese can be reclaimed from the spent leach liquor as manganese oxide and recycled to leaching.

Jan 1, 1979

Graded macadam slag base has been used successfully by the Department of Main Roads, N.S.W., in the construction of Expressways. However, the use of graded macadam in urban conditions introduces problems which can be avoided by the use of material meeting the specification outlined in M.R. Form 744. This paper outlines the rationale behind the technical requirements of the specification for the "Supply of natural gravel or crushed rock for road pavement (bitumen surfaced) M.R. Form 744". A blend of materials produced from slag is proposed as a potential solution for the production of slag base which would be suitable for use in urban construction or maintenance of roads.

Jan 1, 1979

By R. K. Davey

Subsequent to the determination of an ultimate pit and ore reserves for metallic and nonmetallic deposits, it is necessary to develop the most profitable long-range mining sequence for the deposit. Long-range planning is a dynamic process because product prices and costs change, additional assay and metallurgical data become available, mining technology and operating prices and requirements change. The three case studies included in this subsection present different techniques for dealing with the objectives of long-range planning. To be able to forecast production, profitability, and capital requirements, it is essential to have a long-range mining plan.

Jan 1, 1979

By J. T. McLendon

As part of its research project in developing improved refractory materials for metallurgical applications, the Federal Bureau of Mines obtained hot modulus of rupture data at 1,500°,1,550°, and 1,600° C on samples of 13 refractory periclase materials produced from seawater, lake brines, and natural magnesite. The periclase samples also were characterized to establish chemical and mineralogical composition and microstructure. The results indicated that a high MgO content does not necessarily assure good hot strength and that an optimum and varying CaO-Si02 ratio exists for each individual periclase sample.

Jan 1, 1979

By Thomas P. Oxford

The impact of recent legislation on Florida phosphate industry operations has been dramatic. The most significant influences are described: the National Environmental Policy Act of 1969; the Federal Water Pollution Control Act Amendments of 1972; and implementation of the Florida Environmental Land and Water Management Act of 1972. Further discussion includes: critical examination of the recently completed EPA Areawide EIS; potential effects of the Resource Conservation and Recovery Act of 1976; the Surface Mining Control and Reclamation Act of 1977; current local and state laws; and summary of studies on radiochemical effects of mining, seepage from gypsum ponds, and dewatering of waste clays.

Jan 1, 1979

By E. K. Stanek

This volume describes software developed for programmable calculators that is useful in the analysis and design of mine electrical power systems. The programs are equally useful for any industrial or commercial power system. All programs are written for both the HP-97 and the TI-59 programmable calculators. Listings of both versions of the twelve programs that were developed appear in the report. The programs that were developed can be broken into two groups. The first group encompasses design-oriented programs. The second group encompasses analysis programs. For each program the following items are provided: a description of the program&apos;s capabilities, the solution technique used, instructions on how to use the program, a worked out example with data and results and, finally, listings of the programs for the HP-97 and TI-59 programmable calculators. Typical problems that can be attacked with these programs include ground bed design, selection of contactor size, fuse size, relay settings, instantaneous overcurrent trip settings for trailing cables, allowable cyclic cable loading, short circuit analyses, prediction of transient voltages and others.

Jan 1, 1979

Four engineering products and three consumer products have received awards in the 1978 Shell Design Awards competition organized by the Design Institute of the South African Bureau of Standards. Norman Hanson Visiting Fellowship The Norman Hanson Visiting Fellowship, supported jointly by the National Development Fund for the Building Industry (inaugurated by the Building Industries Federation (8.A.)), the Institute of S.A. Architects, the Association of S.A. Quantity Surveyors, and the National Building Research Institute of the CSIR exists to finance fully or wholly visits by eminent authorities from overseas to South Africa for the purposes of seminars, informed discussions, consultation, and possible active participation in scientific, technological, and development projects of importance to the building industry.

Jan 1, 1979