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By J. E. Wey

Extraction of cobalt from cobalt sulfide and cobaltite flotation concentrate from the Blackbird Mine, Idaho, was investigated using an adapted strain of Thiobacillus ferrooxidans. Cobalt extractions as high as 100% were realized in the inoculated experiments, whereas only 4% extraction was obtained in the sterile run. The influence of pulp density on the rate and extent of cobalt extraction was also determined. It was found that the extraction of cobalt followed predominantly the indirect mode of bacterial activity. In this process, ferric iron oxidizes cobaltite to cobalt sulfate and ferric arsenate while being reduced to its ferrous state; the bacteria continuously re-oxidize ferrous to ferric iron. Electrochemical measurements using cyclic voltammetry suggested that cobaltite oxidation involved a number of intermediate reactions.

Jan 1, 1993

Many of the deeper ore reserves in current gold operations as well as new gold deposits consist of refractory ore types. As process development for these mineralizations remains time-consuming and costly, minimization of exploratory testwork and the early identification of feasible process routes is critical. Since most of the processing parameters are related to the mineralogy of the ore (Marsden & House, 1992), thorough mineralogical analyses during exploration and development phases have become a technical and economical requirement. The determination of mineralogy-related processing parameters and especially the gold mineralogy is even more important for these ore types because refractory gold ores consist of many transitions from partially leachable to totally refractory. In addition to sulfide and gangue encapsulation, various other refractory conditions may exist. Together with accessory mineralogical detriments (e.g., alteration/ slimes, reagent consumers, scale formation, mineral preg robbing) they may complicate process selection and hamper optimal plant operation.

Jan 1, 1993

By M. K. Gangal, E. D. Dainty

CANMET/MRL has been contributing to an industry/government program to assess the quality of air in mines, and improve the working environment for Canadian miners. The ultimate aim of this program is to recommend a sampling methodology and appropriate concentration limits for both the soot (diesel particulate matter - DPM) generated by diesel equipment, and respirable combustible dust (RCD) as measured underground. The program was conceived by the Canadian Adhoc Diesel Committee, which consists of representatives from seven major Canadian mining companies, three provincial inspectorates, one union representative, two manufacturers of diesel equipment, and CANMET, a Federal Canadian research agency. This paper describes the modification and laboratory confirmation of an existing methodology for the sampling and analysis of DPM/RCD, including: sampling problems, filter selection, filter efficiency, DPM size distribution, the approximate performance of fractionating devices, and it reports the results of current ambient measurements of exposure levels in Canadian underground mines. Because of the concern about the health impact of DPM/RCD on mine workers, North American agencies are in the process of establishing limits for these aerosols. So far, the Province of British Columbia is the only jurisdiction in North America to legislate the maximum exposure level of RCD in its underground mines, i.e. 1.5 mg/m3 interim level recommended by the Adhoc Diesel Committee. It has also recommended the use of the CANMET/ADHOC RCD sampling protocol.

Jan 1, 1993

By V 9. 0 / 300 dpi

In the time period from the early 1980's to the present, longwall roof support technology has evolved tremendously. Chock supports and caliper shields were replaced by 2-leg or 4-leg lemniscate shields. The lemniscate linkage for which the support is named offers numerous advantages to the sup-port both as a fabricated structure and to its performance in the mining application. The hydraulic system, which is the dynamic element of the roof support, was essentially unchanged in early lemniscate shields with the exception of the complexity of additional hydraulic circuits to power a canopy tilt cylinder and canopy side-seals. The control of these fluid-powered functions was provided by direct manual control of valves energizing individual functions onboard the roof-support or the adjacent roof-support. This control valve-gear was comprised of multiple individual valves arranged in a "bank" or integrated into a single hydraulic distribution block with a single operating handle to select any independent function.

Jan 1, 1993

By D. A. Norrgran

The recent development of rare earth permanent magnets has revolutionized the field of magnetic separation. The advent of rare earth permanent magnets in the 1980's provided a magnetic energy product an order of magnitude greater than that of conventional ferrite magnets. This has allowed the design of high-intensity magnetic circuits operating energy free and surpassing the strength and effectiveness of electromagnets. New applications and design concepts focused on the mineral and metal processing industries have evolved. This technology also led to the development of various magnetic separators specifically designed for mineral processing applications. Applications which were not previously considered are now being applied to primary mineral upgrading and recycling and secondary recovery.

Jan 1, 1993

By Kal V. S. Sastry

Conventional iron ore balling circuits exhibit undesirable surging behavior which is known to result from uncontrolled occurrence of the mechanisms of nucleation, coalescence and layering. This study was undertaken to investigate the mechanism of pellet growth by layering. Several laboratory experiments have been carried out to delineate the effect of feed moisture content and feed quantity. This paper presents an analysis of the experimental results and a simple model to describe the layering process.

Jan 1, 1993

By J. E. Urosek

In October, 1990, a fire started in a large underground coal mine in Western Pennsylvania. During fire-fighting activities, an explosion occurred and all personnel were evacuated. Safe re-entry into the mine was not possible and the mine was sealed. Recovery efforts began in January, 1991 and continued until March, 1991, when permanent underground seals were installed between the fire area and the mine openings. This paper describes an extensive atmospheric monitoring program conducted by the Mine Safety and Health Administration (MSHA), Pittsburgh Safety and Health Technology Center (PS&HTC) including the analysis of mine fire gases, natural ventilation, fan pressure and air quantity distribution.

Jan 1, 1993

By J. H. Hill

The globalization of mineral markets and intense competition in downstream mineral-consuming industries such as transportation, agriculture, and construction are requiring raw materials suppliers to innovate, improve quality, invest in new technology, and control costs. Mineral specifications are becoming more refined, and pressure to improve products is felt from increasing numbers of competing producers, substitute materials, customers, and regulators. As a result, engineered mineral products are becoming more like manufactured ones in terms of cost structure, differentiation, and the importance of market driven, customer specific product development. Engineered mineral products are defined as those where the costs of refining and upgrading outweigh those of conventional mining activities (blasting, crushing, classification, haulage etc.), and where close control of physical and chemical parameters is required for customers' processing and manufacturing applications. This includes industrial minerals such as calcium carbonate, kaolin, mica, specialty oxides, talc, and some metal powders. It excludes most metals and bulk commodity materials such as gypsum, lime, sulfur, and soda ash. Engineered mineral products are utilized in common household goods, and are at the forefront of industrial materials engineering in plastics, ceramics, composites, glazes, coatings, and construction materials. As a group, they introduce interesting questions to the minerals firm. Advanced materials or basic? Diversify or specialize? What are the implications of advanced materials and for mineral markets, and most importantly, where can the producer look for long-term value, volume, and profits?

Jan 1, 1993

By James L. Hendrix, R. Y. Wan, David W. Kappes, Jinrong Zhang, M. C. Fuerstenau, Terence E. Albert

A sulfidic flotation tailings ore, containing 1.14 gpt Au and 242.53 gpt Ag, was treated by low temperature chlorination roasting followed by cyanide or chloride leaching. Eighty per cent of Ag was recovered by cyanide leach when the ore was roasted at 350°C with 50 kg/ton calcium chloride. About seventy per cent of Au was made cyanide amenable by chlorination roasting at 400°C. A better Ag recovery, ninety per cent or over, was achieved by chloride (NaCl+HCl) leach. However, Au recovery was very poor by chloride leach. Ferric chloride, calcium chloride, and cupric chloride were compared as chlorinating agents for their effect on Au and Ag recovery. The study found that low temperature chlorination roasting is very effective for recovering Ag associated with stibnite and stannite. The best chlorinating agent for the test ore was found to be calcium chloride. Parallel roasting-leaching tests indicated that chlorination roasting was far superior over oxidation roasting for both gold and silver recovery.

Jan 1, 1993

By Robert W. Waytulonis

Miners working in underground mines where diesel equipment is used are exposed to exhaust pollutants. These include carbon monoxide (CO), carbon dioxide (CO,), nitric oxide (NO), nitrogen dioxide (NO2), sulfur dioxide (SO2), hundreds of different hydrocarbons (HC) and particulate matter. Evidence from animal inhalation studies and limited epidemiological investigations have led the National Institute for Occupational Safety and Health (NIOSH) to recommend that ‘... whole diesel exhaust be regarded as a potential occupational carcinogen ...’ NIOSH further stated that ‘... the excess cancer risk for workers exposed to diesel exhaust has not yet been quantified, but the probability of developing cancer should be decreased by minimizing exposure…’ The International Agency for Research on Cancer(IARC) reached a similar conclusion, saying that ‘... diesel engine exhaust is probably carcinogenic to humans.’ Before these declarations, there was insufficient evidence concerning the carcinogenicity of diesel exhaust. It was well known, though, that diesel exhaust caused less severe problems, such as headache, eye irritation and unpleasant odors. In 1988, a milestone was reached in the Mine Safety and Health Administration (MSHA) regulatory process. An advisory committee recommended a three-tier approach to regulating diesels used underground-approval of diesel equipment, safety and health. Diesel particulate matter may be specifically regulated. In addition, ambient air quality standards are being proposed that will establish a new standard for CO2 and lower the permissible exposure limits for the NO2, CO, SO2 and formaldehyde emissions that originate from diesels and other sources. Additional safety and emission restrictions are also proposed for diesel engines in coal mines. The goal of the US Bureau of Mines (USBM) diesel engine research program is to minimize the health and safety problems associated with underground diesel equipment use. Part of this program is focused on reducing exhaust emissions from diesel-powered equipment used in underground mines.

Jan 1, 1993

By T. R. A. Davey

Previous publications on the application of EIETSIM include the modelling of an electrolytic zinc plant and a copper flash smelter. In the present case METSIM has been used to model the desilverising of lead by the reagent zinc, whereby a silver-zinc intermetallic compound is formed, and floats out of the lead. This compound has a variable composition, depending upon the ratio of dissolved zinc/silver in the lead bath. Its solubility in lead decreases with falling temperature. A number of variations and modifications of the Davey Desilverising Procedure are modelled, and applied to a wide range of silver contents in lead bullions at several plants. METSIM uses both feed- back and feed-forward controls to simulate plant conditions, and a logic control to distinguish between different phases in the Zn-Ag system. Use is made of extensive (previously unpublished) fundamental data on the ternary Pb-Ag-Zn system, and of plant data, to establish certain operating parameters.

Jan 1, 1993

By S. Yabe

The reinforcement of the annual copper production capacity to 330,000 metric tons has been attained at Saganoseki Smelter & Refinery in 1991, which is one of the largest and most efficient custom smelters in the world. Many operational improvements and technology developments have realized the increase of smelting and refining capacity without adding main facilities to the existing process. The blister copper refining and anode casting process is composed of two 400 tonnes anode furnaces and one double-wheeled casting machine with the capacity of 80 tonnes per hour. The great innovations in this process such as the finding of essential issue on the extending of anode-mould life and the development of a new anode-mould casting machine have raised the operation efficiency by 14% Now, the process is producing 38,500 tonnes per month of best quality anode in well- controlled working condition, and anode productivity per worker increased by 52%. The progress in extending anode-mould life, the mechanism of the new anode-mould casting machine and the increase of efficiency in butane reduction, that were the principal parts of many technological improvements, are described in the present paper, including some operation results.

Jan 1, 1993

By Larry J. Hulbert, Louis J. Cabri, John L. Campbell, Gilles Laflamme, Chris G. Ryan, Soey H. Sie, Rolando Lastra

"Abstract- The mineralogy of samples from the Wellgreen Cu-Ni-Pt-Pd deposit, Yukon Territory, is complex and the metals of interest are contained within fme-grained minerais which vary in size and mineral associations from sample to sample.The major Ni carriers are pentlandite and violarite; the major Cu carrier is chalcopyrite. About 700Jo of the major Ni carriers and 78% of the major Cu qmier will be liberated at a grind of 80% -'}f,.7 J.Uil (-500 mesh) for typical low-grade gabbro (West zone, sample No. 1). For typical ""clinopyroxenite"" (West zone, sample No. 2) and typical ""clinopyroxene-rich peridotite"" (East zone, sample No. 3) the liberation would be 71""lo and 65% for Ni, 74% and 60% for Cu, respectively. Fine grinding, however, cannot liberate the Ni contained in silicates and pyrrhotite, estimated to total24.5% for typicallow-grade gabbro (West zone, sample No. 1), 15% for typical ""clinopyroxenite"" (West zone, sample No. 2), and 12% for typical ""clinopyroxene-rich peridotite"" (East zone, sample No. 3).The principal Pt carrier (sperrylite) varies considerably in grain-size between samples and fme grinding, required to liberate the major Ni and Cu carriers, may be counterproductive in samples where sperrylite is relatively coarse-grained, as sorne would then be unrecovered (e.g. sample No. 1). In addition, sperrylite in samples No. 2 and No. 3 is closely associated with magnetite.Palladium occurs in diverse ways. It occurs in the form of several Pd minerais (e.g. sudburyite, testibiopalladite, merenskyite), as a replacement for Ni in several tellurides, antimonides and tel­ lurantimonides (e.g. melonite), or as very low concentrations in pentlandite (up to 34 ppm), chal­ copyrite (up to 9 ppm), and pyrrhotite (up to 5.6 ppm). Palladium minerais and Pd-bearing minerals are strongly associated with chalcopyrite in sample No. 1 and will thus report to a Cu concentrate. However, 22% of the total Pd is in solid solution in pentlandite in this sample and will thus report to the Ni concentrate. In samples No. 2 and No. 3, less Pd occurs in solid solution in pentlandite, and the PGM are distributed mainly among pentlandite, chalcopyrite, and magnetite in sample No. 2, and among pentlandite, pyrrhotite, chalcopyrite, and magnetite in sample No. 3. Therefore, the feasibility of magnetic concentration should be investigated for samples like No. 2 and No. 3, in order to improve Pt and Pd recoveries.Rhodium was found to occur as rare hollingworthite, in sparse cobaltite (up to 2.7%) and, as low concentrations in chalcopyrite (to 10 ppm) and pentlandite (to 12 ppm) by proton microprobe. Iridium occurs in hollingworthite (up to 7.8%) and very rarely as the native metal or in an undefmed Re-Ir-Os-Ru alloy. Ruthenium was determined by proton microprobe analyses to occur in pentlandite (up to 13 ppm) and chalcopyrite (up to 10 ppm), in addition to rare laurite and Re alloy."

Jan 1, 1993

By R. E. Johnson, W. Kat, B. R. Palmer, van Sandwijk A., G. Van Weert, S. Honingh

In-plant recycling of dust from iron making BF's creates undesirable circulating loads of volatile trace elements such as zinc and lead. Disposal of such dusts creates environmental problems, hence a separate treatment is indicated. Since the bulk of the zinc and lead compounds occurs in the fine dust fraction; hydrocycloning the slurry from the BF gas cleaning operation results in upgrading the material for treatment. A process has been proposed, whereby the zinc and lead are solubilized from the fine fraction with spent hydrochloric acid from steel pickling. The stoichiometry of this autoclave oxidation process is adjusted to simultaneously precipitate, by oxyhydrolysis, most of the iron for recycling to the BF's. Lead and zinc are successively recovered from the filtrate as low chloride precipitates. This paper describes additional testwork, leading to the design of a pilot plant which was planned to begin operation in 1992.

Jan 1, 1993

By F. F. Peng

Fine Coal Cleaning Processes including froth flotation, aggregative flotation or oil agglomeration, depend upon the wettability of coal particles in the aqueous solution. The wettability of coals of various ranks, hydrocarbon oil treated coals and oil-agglomerates have been measured using film flotation, induction timer, and froth flotation. Various hydrocarbon collector dispersion techniques are used to alter the surface wettability of coal particles. Change in wettability behaviors, measured by flotation responses, due to various ranks with or without of hydrocarbon collector modification are explained in terms of surface chemistry modifications as analyzed by induction time, film flotation as well as DRIFT Spectroscopy. The relationship between the wettability of coals and collector treated coals, and floatability are discussed.

Jan 1, 1993

By David G. Dixon

A general, unsteady-state model for leaching of one or more solid reactant species from a non- reactive, porous, spherical pellet is derived in dimensionless form for the interpretation of leaching data, and for use in the design of coarse-ore leaching processes. The effects of diffusion rate, chemical reaction rate, variable reaction order, and competition between multiple solid reactants are examined using the concept of the effectiveness factor. It is shown that the model is capable of simulating both "reaction-zone" and "heterogeneous" kinetics, depending on the choice of three dimensionless parameters. Results of batch leaching tests of artificial ore pellets are presented, and their relationship to the model is discussed.

Jan 1, 1993

By F. Gonzalez, A. Zambrano, J. Schwoebel, S. Kravits

Significant lost time delays were experienced by Carbonifera de Nueva Rosita, S.A. de C.V. ("CNR") during mining development of the Pasta de Conchos Mine ("the Mine") near Nueva Rosita, Coahuila, Mexico. Furthermore, methane gas concentration in the return air course had exceeded 1.0 percent. Resource Enterprises, Inc. ("REI") was contracted by CNR to recommend an approach to reduce methane emissions at the Mine. In order to recommend a degasification approach, REI and CNR obtained geologic and reservoir characteristics of the Double coal seam, Olmos Formation. A vertical core hole was drilled to obtain core samples to determine gas content (average 8.4 cm3/gm) and to conduct a slug test to estimate permeability (34 md). This information was used to simulate gas productivity and drainage effectiveness. The simulation indicated that underground horizontal boreholes would remove significant quantities of gas in advance of mining in a reasonable period of time. Based on the results of the simulation study, an underground degasification drilling program was initiated at the Mine. In a six month period, five long in-mine degasification boreholes were drilled in advance of CNR's three to five years mining projections. Peak gas production from the five boreholes (approximately 2,750 cumulative meters) had exceeded 45,000 m3/D. Results to date have indicated a general reduction in methane concentration in the return air course below 0.8 percent.

Jan 1, 1993

By E. Açma

Sivas-Divrigi flotation plant has a capacity of 90,000 tpy. Beneficiation of the tailings of iron ore magnetic separator seems to be attractive, because of its Cu, Co, and Ni contents. In the experimental work, sulfidic flotation concentrate is produced from these tailings. A roasting-leaching-H2S precipitation procedure is used to treat this concentrate, containing 0.55% Cu, 0.51% Co, 0.74% Ni, and 0.027% Zn. Sulfatizing roasting is carried out in a rotary furnace at 690°C. Roasted product is leached with 10 gpl HzSOl at 70°C and 30% pulp density. For the precipitation of desired metal, H2S is bubbled through the concentrated solution of repeated leaching, under controlled temperature and pH. Final metal recoveries of 91% Cu, 91% Co, and 50% Ni, and 92% Zn are attained. Roasting gases with their 13% SO2 content are suitable for H2SO4 production and the leach residues can be integrated with the iron ore processing plant as they contain 57.4% Fe and very low non-ferrous metals.

Jan 1, 1993

The metallogenic map of New Zealand shows the distribution of metallic mineral deposits, according to type and size, in relation to their geological setting. The major purpose of the map and accompanying 200-page monograph is to summarise the distribution, modes of occurrence and origins of the metallic mineral deposits of New Zealand. The map demonstrates the prospectivity of New Zealand for metallic minerals, particularly gold, silver, iron, and titanium. Information on each deposit is summarised in index tables based on major geotectonic units or deposit/commodity type. The mineral deposits are arranged and discussed in relation to tectonostratigraphic and tectonomagmatic units or terranes, under broad geotectonic divisions of the Paleozoic to Mesozoic Western Province, the late Paleozoic to Mesozoic Eastern Province, the mid Cretaceous to early Tertiary rifting phase, and the late Cenozoic Kaikoura Orogen. Regions or areas of marked concentration of mineralisation are recognised as metallogenic subprovinces or districts, namely: eastern Northland (Hg), the Hauraki Goldfield (epithermal Au-Ag-Pb-Zn-Cu), the west coast of the North Island (shoreline placer Fe), east Nelson (podiform Cr), west Nelson (porphyry Mo), the West Coast of the South Island (shoreline placer Ti), west Nelson-Westland (placer Au), Reefton (mesothermal Au-quartz veins), and Otago (placer Au and mesothermal Au-W quartz veins).

Jan 1, 1993

By S. J. Jung

The prime criteria in the design of underground openings with complicated geological structures is ground control. Stability of underground openings for deep mines is critical because incorrect orientation or geometry of shaft, stope, and accessways often results in the failure of openings due to high stress conditions. Current design procedures for complicated orientation and geometry of mines are rapidly becoming inadequate as mines are being developed. In this study, finite element method has been used with optimization criteria to design more stable and safe underground openings.

Jan 1, 1993