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By Robert G. Bottge, Paul C. Hyndman, Don J. Barnes, Clark A. Roberts

The effect of Federal restrictions on Federal mineral estate in Alaska and the Western States is being addressed by systematic, State-by- State studies. The Bureau of Mines has inventoried and classified 3.5 million sq km (876 million acres) of land, section-by-section, according to 1) mineral ownership, 2) availability for mineral exploration and development as affected by Federal restrictions, and 31, areas containing mines and mineral resources. The availability of Federal land for exploration and development is spatially compared to areas containing mines and mineral resources. The methodology and overall results of the studies are presented.

Jan 1, 1991

Chlorination of organic matter by direct injection of chlorine gas or hypochlorite has been investigated metallurgically worldwide with little understanding of the basic chemistry of the passivation mechanisms in- volved. In this paper, chlorination of carbon is attributed to oxidation-reduc- tions, resulting in surface halogenation of graphitic or amorphous carbon. It is proposed that chlorine and carbon interact to form thin coatings of chioro-carbon complexes that block the adsorption of gold cyanide com- plexes, thus passivating the gold adsorption sites of carbonaceous matter. Analytical, spectrographic, microscopic and electron-optical methods have been applied to demonstrate the proposed mechanism of chlorine-carbon bonding, as well as to evaluate the advantages and limitations of chlorination in the pretreatment of refractory carbonaceous gold ores.

Jan 1, 1991

By William E. Foreman

Editor's Note: For purposes of uniformity throughout this book, Coal Preparation, 5th Edition, the editors have advocated the use of the U.S.A. Sieve Series of testing sieves (see Table 6-2) as the testing sieves of modem choice. The adoption and use of the U.S.A. Sieve Series and its forerunner, the Tyler Standard Screen Scale, has for over seventy-five years introduced uniformity into reports; has simplified the comparison of results; and has provided control for operation of modem coal preparation circuits. While a full explanation of the differences, and more importantly the similarities of these two measuring systems cannot be stated here, it is felt that a brief clarification of terms is in order. The difference between the U.S.A. Sieve Series and the Tyler Standard Screen Scale Sieve Series is the identification method. Tyler Screen Scale sieves are identified by mesh designation with the width of opening varying by the square root of two, or 1.414 times the width of opening in the previous sieve. The U.S.A. Sieves are identified by openings in millimeters or microns and also arbitrary numbers which do not necessarily mean the mesh count; this series uses width of opening variations in the order of approximately the ratio of the fourth root of two, or 1.189. Tyler Standard Screen Scale and U.S.A. Sieves can be used interchangeably, and to avoid confusion the nameplate of all Tyler Screen Scale sieves show the U.S.A. Number, while all U.S.A. Sieves show Tyler Screen Scale mesh equivalent numbers on the nameplate. INTRODUCTION Sizing is the process of separating mixed mineral particles into groups of particles all of the same size, or into groups in which all particles range between definite maximum and minimum sizes. This chapter applies the modem mechanical screen and the liquid-solid cyclone (hydrocyclone) to the process of sizing solid particles as applied to coal preparation. Screening is a mechanical process that separates particles by size. Modem coal preparation is made possible by efficient sizing. Sizing of coal is defined in terms of the opening through which an individual particle will or will not pass, or as two openings, the larger of which passes the particle and the smaller of which retains the particle. Screening accomplishes sizing by passing coal of a wide range of sizes through a series of screens, each of a decreasing size. The individual screen discharges are then directed into different screen products for subsequent sale or processing. Screening in modem preparation plants is done for the following reasons: 1. Removal of fine coal before a size reduction step. 2. Size separation of the coal into a coarse and fine fraction for sized products or for processing in coarse and fine coal circuits. 3. Recovery of heavy media from heavy media coal cleaning circuits.

Jan 1, 1991

By P D. "Takis" Katsabanis

The phenomenon of sympathetic detonations in blastholes is investigated by comparing experimental observations and numerical modelling results. Numerical modelling using the TDL computer code and Forest Fire decomposition rates for commercial explosives has shown the importance of blasthole diameter, impedance of the stemming and host rock. Comparison with experimental observations has also shown that sympathetic detonations cannot always be treated as shock to detonation transition. Examination of previous results which have been obtained from calibrated low amplitude shock experiments reveal that there is an ignition threshold prior to the detonation threshold. The difference between the two thresholds is more pronounced in the case of air bubble sensitized products. The ignition threshold can be very important under the confinement provided by the blasthole and the conditions of application. It also correlates well with the pressures expected at the gap distances of interest in the practical application. It is suggested that critical energies are used as the criterion for cross initiation in blastholes. Practical suggestions based on the numerical calculations and experiments based on these calculations are also given and discussed.

Jan 1, 1991

By D. A. Norrgran

The term "secondary recovery" has recently brought on a new meaning in view of the depletion of natural resources, energy conservation, plant optimization, and the environmental consciousness that has led to hazardous waste management, recycling, and secondary processing. Many secondary recovery processes are being developed applying mineral processing technology. Gravity separation, magnetic separation, and flotation have all emerged as implicit methods for recovering residual values from various process streams and hazardous constituents from waste streams. Recently, a technique for concentrating metallics has been successfully reintroduced. Although the concept of the eddy-current separator was developed over a century ago, (Patent 400317 issued to Thomas Edison on March 26, 1889) it was not until this last decade that it gained prominent acceptance. The evolution of permanent magnets has provided a cost effective alternative for the generation of high intensity magnetic fields. High energy permanent magnets have substantially reduced the capital and operating costs over the electromagnetic circuits employed in antecedent eddy-current separators. Specifically, in recent years, the strength of permanent magnets has increased several fold with neodymiun-boron-iron rare earth magnets now providing an energy product of 35 million gauss-oersted. Figure 1 shows the evolution in the strength of permanent magnets. The development of these rare earth magnets has led to the design of circuits possessing a magnetic force an order of magnitude greater than that of conventional permanent magnetic circuits.

Jan 1, 1991

By Scott G. Britton

Microcomputeranalysis has long been a technique for engineering professionals to improve the theoretical and practical design of continuous mining systems. Such work has been typically composed of modeling observed events and then introducing a variety of known elements with predicted results to compare against the results of the model. Programs written in BASIC, Cobol, Fortran or other language dominated such efforts. These programs have taken years to develop and prove out. This article explores a new management tool used daily at Tanoma Mining Co. (TMC) to track and improve continuous mining systems through the use of microcomputers and Lotus l-2-3 software. Data provided by section foreman, shift foreman, and maintenance personnel are analyzed against predetermined goals. In this way, new production targets are developed, weaknesses in the current mining systems are identified, and the results of changes are measured. The current results of this system on the productive output of TMC systems is on the order of 10% improvement. Thin seam coal mining is an industry within the broader industry of coal mining. Thin seam mining faces the same cost pressures and engineering problems as its higher-seam competitors without the advantages of moving volume per foot of extracted material to stay at an economic parity with others requires additional creativity within the management teams to extract higher productivity gains from the existing workforce and mining systems. TMC operates a deep mine in Indiana bounty, PA, about one hour northeast of Pittsburgh.

Jan 1, 1991

Detect hazards associated with abandoned mine openings through the use of integrated geophysical technology. Background Many abandoned mines in the U.S. present hazards to the public. The first step in abatement of these hazards usually requires locating the abandoned workings. Recent Colorado legislation resulted in a concerted effort aimed at mitigating the hazards associated with abandoned mine workings. The Colorado Department of Natural Resources-Mine Land Reclamation Division (CDNRMLRD) is responsible for locating and backfilling abandoned mine openings such as shafts, adits and collapsed features. Many shafts and adits can be located by inspection, other openings give little or no surface expression and must be located by drilling, or through the use of geophysical methods. A common method used for locating underground mine workings is to drill throughout the suspected area. However, it is prohibitively expensive to drill holes at the spacing needed to detect backlilled shafts and small voids associated with caving and/or chimneying. It may also be dangerous to move heavy equipment over shallow mined-out workings. Geophysical investigations that employ only a single method have had mixed success in detecting hazardous abandoned mine land cavities.

Jan 1, 1991

By H. F. Hennigar, D. L. Pawson, E. J. Foell

Results of an analysis of abyssal benthic megafauna based upon review of nearly 250 hours of videotape and 2149 bottom photographs are presented, and the utility and limitations of such analyses in deep sea biological studies are discussed. The images were acquired at depths of 4400-4800 m during a resource assessment cruise aboard the RV Prospector using a unique, deep-towed, television telemetry system coupled with 35-mm photography. The data review was carried out in support of NOAA efforts to provide adequate environmental baseline information before industrial exploitation of nodule deposits and concurrent monitoring begin.

Jan 1, 1991

By Lewis PJ, Halfpenny R, Craighead GA

Exploration drilling by Joint Venture partners CRA Exploration Pty Ltd and Elders Mining PNG Pty Ltd has discovered a signif- icant copper and gold deposit at the Wafi River prospect, 60km WSW of Lae in Papua New Guinea. An indicated resource of 18Mt at 2.5g/t Au using a lg/t cutoff has been delineated in Zone A. No estimate has been determined for the separate copper occurr- ence at Rafferty's Zone but the copper will be significant to the project. Metallurgical studies on the gold indicate that the primary ore is refractory to direct cyanidation giving a highly variable and inadequate response. All conventional refractory ore oxidation techniques perform well on both ore and pyrite concentrate and oxidation occurs rapidly. No metallurgical studies on the copper mineralisation have been undertaken. Hypogene covellite and chalcocite copper mineralisation is associated with an intensely quartz-stockworked, and quartz and alunite-altered intrusive. Economically significant gold mineralisation occurs in distal subhorizontal lenses, within a sedimentary host, that plunge toward the intrusive. These lenses are sandwiched between overlying quartz and alunite-altered zones and underlying quartz and smectite zones in a mixed zone of quartz, dickite, kaolinite and illite alteration. The alteration and mineralisation is classified as a high sulphidation, epithermal style resulting from the influx of hot, acid magmatic fluids. Preliminary land ownership, road access, power supply and mine infrastructure studies are in progress. The project is currently at an advanced exploration stage.

Jan 1, 1991

By Rowley M, Bradford P

Plutonic Resources Limited (formerly known as Pioneer Mineral Exploration Limited) delineated, developed and operates the Plutonic Gold Mine located 180 kms northeast of Meekatharra, Western Australia. Gold mineralisation was discovered in the Marymia greenstone belt by Great Central Mines NL (GCM) in 1988. There was no previous, recorded gold mining activity in the area. In May 1989, Plutonic Resources Limited (PRL) entered into an agreement to acquire a 51 per cent interest in the three Mining Leases containing the Plutonic deposit from GCM. Subsequently in December 1989, PRL acquired the remaining 49 per cent interest in the Mining Leases. PRL and GCM are also involved in a 51:49 regional joint venture on extensive Exploration Licences in the vicinity of the Mining Leases. Following due diligence validation, reserve delineation and testwork, a feasibility study was undertaken in conjunction with JR Engineering Services, which led to the financing and development of the project for operation in August 1990.

Jan 1, 1991

By Alastair C. Torrance

"A brief review of the Australian mining industry is given followed by a more detailed treatment of a study of the influence of primer Size on explosive performance. This is based on a joint research programme conducted by BHP Central Research Laboratories and Dyno Wesfarmers Ltd and examined the effect of the size of cast primers on the run up and steady state detonation velocitiesof ammonium nitrate based explosives as a function of blasthole diameter. The field trials examined a numter of the Dynamo 'Westfarmers HDF series of primers in conjunction with ANFO, emulsion and watergel explosives. Results indicate that the iun up velocity of 187 mm diameter ANFO charges is negligible using cast primers as small as 150g. However, emulsion and watergel explosives did exhibit run up in both 187 and 3:1mm diameter blastholes, independent of the size of primer. This could last from 7 to 10 blashole diameters"

Jan 1, 1991

By Charles F. Herbert

The waves of prospectors who struggled across the wide Alaskan wilderness between 1898 and 19 10 came close to but did not actually find the rich copper/zinc/silver deposits strung out along 161 km ( 100 miles) of felsic schist in the remote Brooks Range of northwestern Alaska. They had heard rumors of gold in the valley of the Kobuk River, so they skirted the Arctic ice pack in the Chukchi Sea and, in a force at least 800 men strong, ascended the Kobuk River in 1898. Twenty-eight placer mining camps were established but only a handful survived for more than a few years. One of the placers that died rapidly was Ruby Creek. A map showing the location of Alaskan mineral deposits is given in Fig. 1. The Ruby Creek miners, disappointed with the scarcity of gold in that creek, followed copper-bearing float to two places where the float was especially plentiful. Pits, a short adit, and a shallow shaft uncovered copper carbonates, bornite, and chalcopyrite in fractured limestone but the remoteness of the district blocked efforts to sell the claims or to raise capital for development. Shortly after 1906, the copper prospects were abandoned and, except for an account published in 1913 by the US Geological Survey, they were forgotten, as were the names of the prospectors.

Jan 1, 1991

By Jeffrey B. Osmint

The Bureau of Mines Information and Analysis Directorate collects worldwide data on virtually every commercially important nonfuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. The Bureau's data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 329), which placed the collection of mineral statistics on an annual basis. The most recent authority fur the Bureau of Mines survey activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96479, 96th Congress), which strengthens protection fur proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1991

By John L. Stauffer, Allan Lipton, Kim Leitzel, Lesley Gaydos, Laurence M. Demers, Douglas C. Kuhn

Eicosanoids and cytokines produced by the alveolar macrophage (AM) are key mediators of pulmonary inflammation and fibrosis resulting from occupational exposure to mineral dust. In order to determine if eicosanoid and cytokine production are altered by chronic inhalation of coal dust, we compared the production of prostaglandin E2 (PGE2), thromboxane A2 (TxA2), leukotriene B4 (LTB4), interleukin 1 (IL-1), tumor necrosis factor (TNF) and platelet-derived growth factor (PDGF) by cultured AM from non-smoking normal human volunteers and coal miners. Inhibitors of eicosanoid biosynthesis were administered to AM from coal miners in order to determine if a link between eicosanoid and cytokine production exists in these cells. Basal PGE2, TxA2, TNF and IL-1 production by AM from active miners was increased compared to AM from normal volunteers. However, the production of these eicosanoids and cytokines by AM from former coal miners was reduced compared to control AM. Administration of the cyclooxygenase inhibitor, suprofen, and the lipoxygenase inhibitor, nordihydroguaiaretic acid, reduced PGE2 and TxA2 production in miners' AM but had no effect on LTB4, IL-1 or PDGF production. Specific inhibition of thromboxane synthase by UK38,485 was associated with a significant reduction in TNF production in active miners' AM but had no effect on PGE2, LTB4 or IL-1 production. The prostacyclin analogue ZK96,480 also specifically inhibited TxA2 production in active miners' AM. The results of these studies suggest that coal dust exposure is associated with alterations in AM eicosanoid and cytokine production which may be relevant to the development of pulmonary inflammation and fibrosis. In addition, the lack of effect of inhibitors of PGE2 biosynthesis on IL1 production in miners' AM suggests the production of these intercellular messengers may not be linked in AM chronically exposed to coal dust.

Jan 1, 1991

By Rayner J. G, Leckie J. F, Moorehead C. F

The Coronation Hill gold-platinum-palladium prospect is located in the valley of the South Alligator River (latitude 13'35'S, longitude 132'36'E), about 80 kilometres east of Pine Creek in the Northern Territory. Coronation Hill was one of thirteen sites in the South Alligator Valley at which uranium was mined between 1955 and 1964 after initial discovery by the Bureau of Mineral Resources in 1953. Most of the mines were operated by United Uranium No Liability. The Sleisbeck mine 25 kilometres south of Coronation Hill was operated by North Australian Uranium Corporation and the group of mines at Rockhole about 20 kilometres to the north-west of Coronation Hill was operated by South Alligator Uranium No Liability. The uranium mine at Coronation Hill produced about 26000 tonnes of ore averaging 2.6 kg/t U308 with an estimated average gold grade of 10.4 g/ gold. Gold was commonly associated with the uranium mineralisation and was recovered at the gravity treatment plant at El Sherana. Gold was also recovered in 1986 by Pacific Gold Mines Limited by treating the tailings from the Moline and Rockhole uranium leach plants at a CIP plant at Moline. With the completion of uranium contracts in 1964 mining in the South Alligator Valley ceased. Exploration for uranium continued in the area during the 1960s and 1970s with no success. The Coronation Hill Joint Venture (BHP Gold Mines Limited 45 per cent, Pioneer Minerals (Gold) Pry Ltd 45 per cent, Notgold Limited 10 per cent)carried out the first exploration specifically targetted at gold in 1984 with the drilling of five vertical drill holes which indicated high potential for a substantial gold resource at Coronation Hill with no associated uranium. The Joint Venture has sub- sequently drilled about 25000 metres of diamond drill holes at Coronation Hill alone. Analytical results from 1985 drilling established that platinum and palladium were associated with gold. An indicated resource of 3.49Mt at 5.12g/t Au, 0.21g/t Pt and 0.56g/t Pd has been calculated using a lg/t Au cut off.

Jan 1, 1991

By P. N. Bradbury

The coal companies of today have to make all of their in-the-field managers MAINTENANCE PRODUCTION MANAGERS. By using a computer application to monitor all aspects of the daily production as well as the maintenance, a company can immediately effect a cost reduction by studying the down-time and delay trends on an everyday basis. This paper will outline how a company can use a program to not only put a stop to the increasing supply and maintenance costs but start trimming each of these cost centers while actually increasing the efficiency and productivity of the current work force.

Jan 1, 1991

The optimisation of human resources provides the path to improving productivity. British Coal has the goal of competitiveness with a quality product in ensured supply. High class skilled professional management teams will analyse job definition and selection procedures for posts, as well as objectives for and delivery of effective management training.Some fundamental changes in attitudes towards training as a means of achievement may be by managers at all levels self-examining their abilities to improve their styles, and by moving training more into the world of high technology techniques. The resulting improvements to management and training with attendant cost benefits will be enjoyed by the companies responding most effectively to these challenges.

Jan 1, 1991

By Hendrix J. L, Nelson J. H

A study was conducted to examine how pretreatment of carbon-bearing gold ores with chlorine enhances gold recovery by cyanidation. It is hypothesized that metal species (including iron and copper) dissolved during chlorination adsorb on the carbon surface hindering the adsorption of dissolved gold. To test the hypothesis, samples of several sulfide minerals were subjected to reaction with sparged chlorine gas to determine which, if any, dissolve faster than gold under these conditions. Then, a synthetic carbonaceous refractory gold ore containing pyrite, chalcocite, activated carbon, and gold was subjected to gas sparging. The results of these experiments showed that chalcocite and arsenopyrite dissolve so that metal (copper and iron) is put into solution slightly faster than gold under the same chlorination conditions. Also, it was observed from the experiments that gold adsorbs on activated carbon during chlorination, but is replaced by copper and iron as the chlorination process dissolves more of the chalcocite and pyrite. The study concluded by investigating ferric chloride addition prior to chlorination to hinder gold adsorption on activated carbon.

Jan 1, 1991

By Gordon R. S. Smith

This paper is in two parts. The first part describes Membrane Back-Pulse Filtration and the effects of very short filter downtimes on cycle filtration rates. Part II describes the use of Membrane Back-Pulse Filtration for combined thickening and polishing soda ash thickener feed material followed by a description of computer modeling of CCD circuits by Iterative solver.

Jan 1, 1991

By E. G. Noble

Microbial leaching is being investigated as a method for recovering the metal values from a domestic low-grade manganese wad ore. Early work showed that heterotrophic microorganisms present in the ore solubilized manganese when cultured in a glucose-mineral salts medium. More recent shake-flask tests using molasses as the sole nutrient source extracted 97 pct of the manganese from minus 300- µm ore in 4 weeks. Column bioleaching with the molasses medium solubilized 99 pct of the manganese from minus 6.3-mm ore in 50 weeks. The results of flask, column, and lab-scale heap bioleaching studies are presented.

Jan 1, 1991