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By F. A. Schinner

The present study has investigated the leachability of cadmium sulfide minerals by Thiobacillus ferrooxidans and the electrochemical reactions involved in the process. Using a cyclic voltammetric technic and carbon-paste-CdS electrodes, it was found that the bio-oxidation of semiconductor cadmium sulfide minerals consisted of a number of intermediate electrochemical reactions. The overall reaction was found to be controlled by solid state diffusion as suggested by the chrono-amperometric and chrono-potentiometric measurements. The activation energy of solid state diffusion was determined by the Sand's method to be AE=24.3 kJ. A generalized mechanism was proposed for the bacterial oxidation of cadmium sulfide by T. ferrooxidan and an explanation given for the importance of high redox potential of leach solution versus the decomposition potential of the sulfide mineral. Furthermore, the effects of n-type or p-type character of CdS substrates relative to their bioleachability was discussed.

Jan 1, 1993

By Marco Olper

The CX-EW technology, developed by B.U.S Engitec, is improved introducing besides the battery paste electrowinning, the direct electrorefining of metallic lead (grids and poles) obtained from CX breakers. This new concept of electrorefming the antimonial lead scrap is aimed to the production of 99.99 lead and of slimes with high antimony content, avoiding gaseous emissions in melting lead scrap, and expensive and pollutant thermic refining operations. In this way, practically all lead content in the battery is available as 99.99 lead, hence with a wider market for the lead recyclers. This paper will describe the tests performed on a pilot plant scale with special reference to the relatively low energy consumption of the process.

Jan 1, 1993

By K. J. Sollman

As a class, silicate minerals have likely found the broadest, if not largest volume, use in combination with polymeric binders of all industrial minerals. Among the silicates, calcium metasilicate, wollastonite, enjoys a front runner position in a near universal sense. It is a viable and desirable part of composites ranging from thin films to large moldings; from a common filler/extender for paint for your garage to a reinforcement for the exterior surfaces of a luxury vehicle affordable to very few. This article is focused upon the variations in particle morphology and the surface characteristics which, by way of commercial examples and discussion of active research programs, make this environmentally benign mineral so unique.

Jan 1, 1993

The Mahakipawa gold deposit is located 21 km northwest of Blenheim. It became the site of a small hardrock gold rush in 1889 following nearby alluvial gold discoveries in 1888. The study investigates the geology of the area of hard rock mining in the vicinity between Cullens and Waikakaho Creeks. The Marlborough Schist which hosts the gold depos, it consists of polydeformed greenschist facies quartzofeldspathic psammitic, pelitic and volcanigenic schist.

Jan 1, 1993

By J. A. Madonna

Universities and colleges in three countries, Australia, Canada and the United States, recognized the need to establish and/or reorganize geoscience programs at the vocational and two-year technical levels. To accomplish this goal, a cooperative study with industry in one state or province from each country was initiated. These include 1) Tasmania, Australia, 2) British Columbia, Canada and 3) Alaska, United States. Over one hundred mineral industry organizations cooperated in the study by providing information regarding their specific training needs for support personnel. The data gathered has been used to identify training areas for semi-skilled, skilled and technical personnel in geochemical mineral exploration, including, but not limited to, geological skills, geochemical skills, environmental skills and computer skills. With the areas of major educational need defined for geochemical exploration, an educational field skills model has been developed for the three levels of training. The depth of each level of education and the training objectives for the work force at each level will be discussed.

Jan 1, 1993

By D. W. McDonald, N. A. Duke, R. L. Hauser

"Abstract- The NERCO Con Mine is situated in the amphibolite facies aureole of the Western Plutonic Complex overprinting the Yellowknife Greenstone Belt. Metamorphic grade of the upright monoclinal basaltic succession decreases from hornblende-amphibolite facies along the border of the batholith to greenschist facies. Metamorphic isograds, subparalleling the faulted margin of the batholith, transect volcanic stratigraphy and coincide with major gold­ bearing shears.Gold mineralization is confined to north-striking, west-dipping shear zones where hanging­ wall amphibolite facies mineral assemblages retrogress to chlorite-carbonate-sericite-sulfide bearing schists hosting multiple generations of quartz-ankerite veins. The gold-producing portions of the Con and Campbell Shears occur where these structures transect an east trending thermal corridor. The corridor is defined by granitic plugs and a number of related breccia bodies, that can be traced outwards from the batholith across the greenstone belt.Prograde reactions of greenstone during amphibolitization effectively liberate fluids that partition metals. With retrograde reactions at shear zones, gold is precipitated with quartz due to the destabilization of sulfide and arsenic complexes. The coupling of regional prograde metamorphic and restricted retrograde metasomatic overprints suggest mineralization is temporally related to emplacement of the Western Plutonic Complex. Economic gold concentrations within the intrusive corridor indicates enhanced metamorphic overprint of hornfelsed greenstones enveloping satellite intru sives peripheral to the main batholith."

Jan 1, 1993

By D. M. Larsen

Since start-up in 1985 the Cannon Mine has produced and shipped a 170 g Au/tonne (5 oz Au/ton) flotation concentrate to various smelters for gold and silver recovery. Several processed have been investigated to economically produce dore' at the mine site from the refractory concentrate. This paper describes recent laboratory and pilot scale test work utilized in the process design and engineering feasibility study of a 73 tonne/day (80 ton/day) pressure oxidation and CIL facility. The designed pressure oxidation circuit utilizes a series of vertical autoclave units operating at 170°C (338"F) and 1.4 MPa (200 psig). Projected operating costs are discussed.

Jan 1, 1993

By Samuel J. Kosa

The Monotube is a uniformly tapered high-strength steel shell pile manufactured for friction pile applications. The Monotube pile was developed in the early 1920's in Canton, Ohio. Its first commercial installation was an Ohio railroad trestle in 1926. The Monotube has been manufactured in the same Canton plant since its inception. The Monotube is produced in four diameters, 12, 14, 16 and 18 inches, with U. S. Standard Gage wall thicknesses of 9, 7, 5 and 3. The uniformly tapered Monotube section can be manufactured in one of three rates of taper.

Jan 1, 1993

By J. H. Meza V

La Caridad operated at only 65% of design capacity during the first five years of operation. After the first major shutdown and repairs to the furnace in mid- 1992, the smelter quickly reached 95% of design capacity. Converter operation is now more efficient; blowing times have decreased from about 1.7 to 1.2 min/ton of matte. Anode copper production is now 15000 tons/month. The increased efficiency provided by better coordination and scheduling ensures La Caridad's ability to operate at present and expanded production capacity while simultaneously meeting environmental control standards.

Jan 1, 1993

By R. B. Hopler

Explosives R&D has historically been motivated by coal mining. Whether to solve safety problems or to improve productivity and cost, the result has been the same: better explosives products and initiation systems. This process continues at an accelerated pace today due to the tools presently available to the explosives and mining industries.

Jan 1, 1993

The demand for minerals will grow strongly to satisfy the needs of an increasing world population for materials and energy. The technical problems involved in producing these minerals will be daunting and the engineers who will have the responsibility for designing and controlling the mineral production processes must have a high level of skills. This will place a heavy responsibility on the education system. A small number of large, well equipped university departments dedicated to mineral processing and having a close working relationship with the mineral industry, and an international orientation, will be much better placed to meet the needs than a large number of small ill-equipped departments which find it difficult to remain viable in modem universities. Courses in mineral processing must be designed to meet the scientific and technological needs of industry and full use must be made of innovative educational techniques such as video conferencing in delivering the courses. The concept of a major international network of major mineral processing departments which is designed to make best use of scarce academic resources is important and should be considered by the International Committee of the IMPC.

Jan 1, 1993

By Michel Jebrak, Claude Bellehumeur

Regional and orientation geochemical stream sediment surveys were carried out by the Quebec Department of Energy and Resources in southwestern Quebec, over a part of the Mont Laurier Terrane of the Grenville Province. The area contains some small stratiform zinc deposits. The response of Zn mineralization to geochemical surveys is weak; the known mineralization is not dermed by anomalous samples and consistent patterns. This study uses a technique that increases the geochemical signature of Zn mineralization in filtering out geochemical background components related to lithologies and surficial conditions. The background variations were modelled using principal component analysis, and the filtering technique consists of the partial reconstruction of the data matrix from results of principal component analysis. The filtering procedure considerably enhances the Zn anomalies located in the catchment basins of Zn deposits, and defines some new anomalies in proximity to the marbles of the Mont-Laurier Terrane, the principal metallotect of Zn mineralization.

Jan 1, 1993

By Dani J. Alldrick, Alastair J. Sinclair, Colin I. Godwin

"Abstract - The Stewart mining camp has a long history of precious and base metal mining. The camp is abundantly mineralized, with more than 200 widespread, varied, vein prospects, deposits and orebodies. These show wide variations in the mineralogy of ore, gangue and alteration assemblages, and wide variations in textures and structural settings. This report establishes the timing of the different metallogenic epochs and suggests a specific exploration application for systematic lead isotope analyses.Galena lead isotope ratios from a range of mineral occurrences indicate that all these varieddeposits formed during two main mineralizing events. Lead isotope data from the Stewart mining camp do not provide absolute ages for the formation of mineral deposits, but the relative distributions of data are consistent with dates determined in other studies. One ore-forming episode occurred in the Barly Jurassic and the other in the Middle Eocene. Both metallogenic epochs were brief, regional-scale phenomena. Sorne deposits from the younger mineralizing episode were em­ placed adjacent to or superimposed on the older deposits.Field and laboratory studies show that the two metallogenic epochs are characterized by different base and precious metal suites: Barly Jurassic gold-silver-zinc-lead-copper; and Middle Eocene silver-lead-zinc. Therefore, showings of different ages have different base and precious metal potentials and deserve different exploration emphasis. Lead isotope studies provide a reliable, cost-effective method for evaluating the age and commodity potential of small or recently discovered mineral showings and for setting exploration priorities on properties with several varied mineral occurrences . The determination of the age and metal potential of a prospect at an early stage of exploration may govern the urgency, intensity or even the necessity for further exploration work."

Jan 1, 1993

By Lawrence K. Nordell, Vinit Sethi

Published standards and specifications do not adequately cover engineered class pulleys for modern high strength steel cord belt conveyors. This paper discusses the Conveyor Dynamics, Inc. (CDI) design criteria and stress analysis techniques emphasizing the finite element method (FEM), fatigue failure criteria, design limits and manufacturing requirements to ensure successful and safe pulley installations.

Jan 1, 1993

By R. L. Nyirenda

The use of ammoniacal ammonium carbonate (AAC) leaching for the treatment of carbon steelmaking EAF dust has been investigated on a laboratory scale. The experiments have been conducted on dust samples obtained from three European steelmaking companies. As received, the dusts were found to be toxic when tested according to current EPA toxicity testing procedures. Toxicity was on account of the leachability of one or more of the following elements: Ag, Hg, Pb, and Cd. Leaching experiments with concentrated AAC solution at 40 " C showed that zinc oxide present in the three dust samples, 60-80% of the total contained zinc, was rapidly solubilized. Data on the dissolution characteristics of Cd, Fe, Pb, Mg, and Mn are also presented. Toxicity tests conducted on residues of the leaching experiments found these to have leachates below past and current EPA toxicity threshold limits.

Jan 1, 1993

By Charles P. Lazzara, Alex C. Smith, Mark W. Ryan

The U.S. Bureau of Mines conducted a study to evaluate the effect of ventilation on the performance of automatic sprinkler systems in extinguishing wood crib fires. Experiments were conducted at airflows of 0, 0.76, 1.5, 2.5, and 4.1 m/s. Two experiments were conducted at each airflow, using 74° C fast response pendent sprinklers in one experiment and 74° C fast response horizontal sidewall sprinklers in the other experiment. In the experiments at airflows of 0 and 0.76 m/s, sprinklers were located directly above the fire and 2.4 m upstream and downstream of the fire. The sprinkler directly above the fire was the only sprinkler to operate with no discernible difference in the suppression capability of the pendent and horizontal sidewall sprinklers. In the experiments at airflows of 1.5 and 2.5 m/s, sprinklers were located directly above the fire and 2.4 and 4.8 m downstream of the fire. The sprinkler located 2.4 m downstream was the only sprinkler to operate with the horizontal sidewall sprinkler being more effective in extinguishing the wood crib fire. The average response times of the sprinklers at airflows of 0.76, 1.5, and 2.5 m/s were 3-1/2 times the average response time of the sprinklers at 0 m/s. The results of this study will help enhance the safety of the nation's miners.

Jan 1, 1993

By Chaves AP, Delboni H. Jr

Thermal comminution is an industrial process specially suited to very abrasive material, when contamination with Fe from wearing parts of conventional crushing and grinding equipment must be avoided. It involves an initial step of heating the material to be comminuted, followed by sudden cooling (quenching) and finally by a conventional mechanical process to disassemble the particle aggregates. The thermal step is, in fact, a pre-fracturing process. The heating operation causes changes in phase of the minerals and changes in volume of these minerals and other substances included in pores and cracks. The cooling operation causes thermal shock reversions or the phase transformation and consequent generation of internal stresses, high enough to fracture the solid.

Jan 1, 1993

By R. L. Derick

The Orchard Valley Mine, a large underground coal mine located in western Colorado, experienced a major mine fire during an idled Sunday on June 1, 1986. This mine had extensive problems with spontaneous combustion near the coal outcrop. Spontaneous combustion has been determined to be the probable cause of that fire. Preparing for a mine emergency was an on-going task. Once the emergency occurred, much of the preparation work was implemented and aided in controlling the situation. Later, the successes and shortfalls that arose from that emergency were analyzed for future course of action. This paper summarizes the activity that led up to the major fire, the handling of that emergency, the lessons learned, and the changes implemented.

Jan 1, 1993

By Harry Deitzer

Within the industrial marketplace barium sulfate has an established role as a filler or extender pigment for use in a wide array of applications. The focus of this paper is to outline a number of these applications and in each one characterizes those features of barium sulfate which provide value. Following this is a discussion of the process techniques which have been used to develop value from a selected class of barite ores found in southern Missouri. It is appropriate to define some terms which may help in clarifying some concepts as presented. Use of the term barium sulfate refers broadly to the chemical compound BaSO4 Barite will generally refer to the naturally occurring barium sulfate ores and their properties. Barytes, whether bleached or not, will refer to barite ore made suitable for industrial applications.

Jan 1, 1993

By J. D. Miller

Air-sparged hydrocyclone (ASH) flotation is a high-capacity flotation technology originally developed in the Department of Metallurgical Engineering at the University of Utah for processing mineral resources. However, the technology has been found to be useful in industrial waste processing, in the recycle of secondary resources, and in remediation of environmental problems. For example, areas in which the ASH technology is expected to have potential application include cleaning of waste coal fines, air stripping to remove volatile organics from drinking and process water, water disinfection by ozone or chlorine sparging, dispersed oil removal from water, and contaminated soil remediation. Recently, the ASH has been studied extensively for deinking flotation in the wastepaper recycling industry and has been shown to have excellent efficiency/capacity. In fact, a 20-million-dollar plant has been in operation since June 1992. The ASH technology can provide a specific capacity hundreds of times more than that which can be achieved with conventional flotation equipment and in certain instances is expected to provide superior separation efficiencies when compared to other technologies. The design and principles of ASH flotation are described. Experimental data for fine coal flotation, volatile organics stripping, and deinking flotation for paper recycle are presented and discussed. Finally, other potential areas of application for environmental technology are considered.

Jan 1, 1993