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By Joseph E. Worthington

The present-day Northumberland gold mine is one of the deposits generally characterized as a Carlin-type occurrence. It lies at the crest of the Toquima Range in Nye County near the center of Nevada. Gold mineralization occurs in two modes, in argillaceous and in silicified limestones, and is generally very fine-grained or micron gold. The Northumberland district has had a history that is typical of many western gold districts: minor production prior to World War II and intermittent exploration thereafter until a combination of geological insight, improved economics, and the advent of heap leach technology created the Northumberland gold mine. Nye County, Nevada, was sparsely populated and little explored in the early years of the settlement of the west; the Northumberland district was not established until 1866. Initial interest was in silver and the district operated as a very small producer for the next seventy years. The disseminated gold occurrences in silicified limestones were recognized and Northumberland Mining Co. was organized to develop the property in the late 1930s. Northumberland Mining Co. actually conducted drilling operations (over 200 drill holes) and mined from small open pits in the silicified limestones. They ultimately produced almost 936 kg (33,000 oz) gold before being shut down by War Production Board Order L-208 in 1942. After World War II gold mining activities were essentially nil for over a decade due to the poor economics of gold production. The property was, however, a known gold producer and attracted recurrent exploration attention. About 45 holes were drilled under the direction of Peter Joralemon for private interests between 1959 and 1963. Next Kerr McGee drilled about 25 holes during 1963 and 1964. Some- what later, in 1968, Homestake drilled 20 holes. The property was then acquired by Idaho Mining Co. which drilled about 30 more holes between 1972 and 1974. By this time the Northumberland mine was becoming somewhat shopworn with over 300 holes drilled. Interest in gold prospects was increasing substantially in Nevada, how- ever, due to rising gold prices in late 1974, and several companies were interested in continuing exploration at Northumberland. In 1975 Cyprus Mines Corp. was successful in obtaining a joint venture arrangement with Idaho Mining Co. for further exploration and development of the property. The overall Cyprus exploration program was under the direction of James G. Hansen, Vice President Exploration. The geologist recommending acquisition of Northumberland was Peter E. Chapman who reported to Joseph E. Worthington, Manager of U.S. Exploration for Cyprus. The basis for selection of the Northumberland mine as an exploration target for Cyprus by Chapman was essentially prior knowledge of regional and 16cal geology and of the mine. Exploration for the next few years was directed by Chapman under the supervision of Worthington. During 1975 and 1976 rotary and check core drilling were conducted that indicated that a substantial Carlin-type or disseminated, low-grade gold deposit occurred in two separate bodies. Drilling was based on geologic mapping and rock chip geochemical sampling. Both ore zones were reflected at the surface as gold and arsenic anomalies in rock chips. Heap leach tests attempted in 1977 were aborted by a flash flood, but were completed in 1978. Engineering studies occupied the next couple of years until the property achieved production in the fall of 1981. It is now producing by open-pit mining with gold recovery by heap leaching and cyanide extraction at a rated capacity of approximately 2722 t/d (3000 stpd) ore. Metal recovery has been projected (probably conservatively) at 5 10 kg/a (18,000 oz per year) gold and 1.6 Mg/a (59,000 oz per year) silver. Reserves are reported to be adequate for ten to fifteen years of production. REFERENCES Anon., 1981, "Gold in Nevada," Span Magazine, Vol. 21, No. 3, Standard Oil Co., pp. 6-9. Koschman, A.H. and Bergendahl, M.H., 1968, "Principal Gold- producing Districts of the United States, Professional Paper 610, US Geological Survey, p. 193. Kral, V.E., 195 1, "Minerals Resources of Nye County, Nevada, Bulletin, Vol. 45, No. 3, Geology and Mining Series 50, Nevada University.

Jan 1, 1985

By Q. G. Liu

New solid-state electrochemical sensors 1;.1sing Li2SO4-Ag2SO4 electrolytes have been developed to measure SO2 and/or SO3 in gas mixtures. Silver embedded in part of the electrolyte is used as the reference electrode. Although single-phase electrolyte sensors yield accurate results for one to two days, a two-phase electrolyte cell exhibits excellent long-term chemical stability. For example, stable and accurate potent iometric responses have been obtained over a six mo.nth period. The. advantages of the two-phase electrolyte ( 23 mol% Ay 2SO4 ) cell include excellent mechanical strength on temperature cycling and an insensitivity to compositional variations in the electrolyte and to temperature fluctuations. Experimental tests have shown excell.ent results in SO2-air. mixtures with the SO2 concentration ranging from 3 to 10,000 ppm (vol). However, the SO2 concentration range was limited by a lack of standard gas mixtures, and our sensor cells can be used to measure S02 concentrations significantly less than or larger than our experimental range. Results also indicate that the presence of significant concentrations of CO2 and H2O in the gas mixture has no effect on the sensor response. Thus the two-phase electrolyte ( 23 mol% Ag2S04) sensor has exceptional selectivity, reliability and long-term chemical and mechanical stability.

Jan 1, 1985

By L. B. Hale

"Introduction This paper will discuss the current operations of Westar Mining Ltd. and give a brief history of the company and of the Crowsnest Pass area. Westar is an integrated company involved in mining, processing and marketing coal from its mines in southeastern British Columbia and shipping coal from Westshore Terminals at Roberts Bank, located just south of Vancouver, B.C. It is two-thirds owned by the B.C. Resources Investment Corporation and one-third owned by the Mitsubishi Corporation of Japan and a consortium of Japanese coal consumers. Operations in southeast British Columbia consist of four coal mines and two processing facilities (Fig. 1). The Elkview Coal Processing Plant near Sparwood, B.C. receives its raw coal from Balmer operations (Harmer open pit), Balmer South (Panel 6) an underground hydraulic mine, and Balmer North an underground room-and-pillar mine. The fourth mine, Greenhills, an open-pit operation, is located near Elkford, B.C. and has its own processing plant. The Balmer mining and processing complex is the largest metallurgical coal facility in Canada producing up to 7 .5 million tonnes of clean coal per year. The Greenhills operation, completed in mid-1983, has a capacity of 2.8 million tonnes. The high-grade metallurgical and thermal coal produced is primarily for export markets. The major customers are Japan, Korea, Brazil, Pakistan, Chile and Taiwan.Our coal and that produced by other mines in Alberta and British Columbia is shipped to the international markets through Westshore Terminals Ltd., a wholly-owned subsidiary. Westshore will have an annual capacity of 22 million tonnes of coal and accommodate ships of up to 250,000 dead weight tonnes by 1984 when its current expansion program is completed."

Jan 1, 1985

By Norman L. Weiss

The full importance of tailings disposal is yet to be realized by the mining industry, but our awareness of its present and future implications is growing faster, perhaps, than any single phase of ore processing. Few engineers can look very far into the future because of the complexity of the problems that may confront us if we project from the general indifference of past years through what we are already being expected to correct in existing operations, to confrontations with new statutes and an awakened public in any new plants hence- forth. The mistakes of the past have not been limited to the United States nor even to other countries of the Western Hemisphere. Indeed, all continents and subcontinents have suffered from myopia in releasing the tailings without retaining responsibility. However, the US as one of the world's great leaders in technology has a particularly unimpressive record. It may be safely generalized that the degree of control applied to the tailings of a milling operation has depended upon several factors more important than national boundaries. Thus in arid and semiarid climates no incentive was needed other than the scarcity of water to create a permanent and stable lodgment for mill tailings. On the other hand. where water has been plentiful. the temptation to let the tailings run into a river or lake or ocean (at least at certain times of the year) was often irresistible. So we find that modem tailings disposal in the southwest deserts of this country, with one or two notable exceptions where very serious breaks seem to occur at regular intervals, is satisfactory according to the standards of the 195QF and 1960s. while in various operations in Idaho, Michigan, western Colorado. Newfoundland, and elsewhere the record has been less praiseworthy. In the same way, cyanide plants which did not concern themselves about leakage, seepage, spillage, or wastage of tailings pulps with solutions containing toxic levels of free or combined cyanide soon heard a demand for better control. In consequence the industry has seen a growing use of cyanide regeneration of tailings or wash solutions, elimination of leakage, and careful structuring of tailing dams. The chemical and thermal qualities of tailing waters have occasionally been a spur to good tailings management. Some tailings disposal problems for example, the southeastern Florida phosphate clays and the Bayer red muds-have been given the intensive study they merited, but not always with much success.

Jan 1, 1985

By T. R. A. Davey, J. W. Sherman, B. J. DiSanto, G. Bjorling, G. S. Stacey, J. T. Cullom, R. L. Bird, S. E. Woods, J. C. Blair, Jorma Honkasalo

Most pyrometallurgical processes take place at high temperature with rapid chemical reactions when the elements and compounds are usually liquid or gaseous. Smelting. The classical method of obtaining a metal from its ore or concentrate is to smelt it in a furnace. The initial letter "s" of this word implies that, in addition to the physical process of melting, a chemical change also occurs. This is usually the reduction of metal oxide to metal by carbon or through a series of processes involving oxidation and reduction. Since solid-solid contact would not be sufficient to give a high rate of reaction, most smelting reactions occur by medium of two reactions involving solid-gaseous contact: where M represents a metal. The commonly preferred unit for carrying out these reactions is the blast furnace,1 which is a vertical shaft of refractory brick or water-cooled steel in which lumps of metal oxide and coke are fed at the top, and an air-blast is injected through tuyeres (water-cooled pipes) in the bottom. Molten metal is withdrawn from a pool at the bottom of the furnace, while N2, CO, and CO2 gases leave the top of the furnace, carrying some fine dust or fume with them, which

Jan 1, 1985

By Frank Martonhegyi

"The objective of this paper is to review the coal basins in the Canadian part of the Western Cordillera to aid their understanding, and to aid in finding and proving places of economic coal mining potential. Coal occurs in eugeosynclinal basins in the Western Cordillera which evolved through three stages: -from systems of volcanic arcs in the Late Jurassic to mid-Cretaceous; -through an intermediate stage with deposition in increasingly restricted successor basins in Jurassic to Early Tertiary; -to a continental stage by the Eocene. Minor coal seams occur usually in late volcanic arc stage sediments bur they can be locally thick as they are on Queen Charlotte Islands. Successor basins usually show a marine-paralic-limnic evolurion. Signijicanr coal deposits occur in the tarter two sequences in the Whirehorse (Tantalus) and Bowser (SkeenaSusrur) basins. Currenr activities are intensive in the more accessible Bowser Basin, for example at Telkwa, Susrut River and on the Groundhog coal field. On Vancouver Island major coal seams occur in cyclic sediments, but the more accessible deposits are mined our. Exploration renewed recently in the less accessible northern part of the Island, for example Quinsam, for surface mineable coal. The Western Cordillera is a mosaic of allochtonous tectonic blocks. They originated from the south and were displaced northward by several hundred kilometres. Many Tertiary coal basins are related to strikeslip transcurrent faults along which the later part of displacement took place, for example the Dawson coal area in the Tintina Trench. Tensional and dipslip normal faulting also created or enhanced sites for thick peat accumulation. For example at Hat Creek 280 m of coal occur in a 550 m section. Secondary structures are often better exploration targets than the main fault zones. Pluvial and alluvial fan environments away from the main drainage are usually the favourable sites for thicker and cleaner coal deposition."

Jan 1, 1985

By Thomas O. Glover

The mining industry of Cameroon continued to be dominated by crude petroleum. Crude petroleum production has become the most important facet of Cameroon's economic development. Oil production was estimated to be 6.3 million tons in 1983 compared with 5.2 million tons in 1982 and 4.3 million tons in 1981. Over two-thirds of its export income was attributed to crude oil. The country's only refinery, dedicated in 1981, has a production capacity of 2 million tons. Cameroon has become self- sufficient in petroleum products since commissioning the refinery. The oil sector contributed approximately 13.5% to Cameroon's gross domestic product in 1982-83. Oil production was expected to rise from 125,000 barrels per day in 1983 to 156,000 barrels per day in 1985 when output peaks. Cameroon's ultimate recoverable reserves have been calculated at 100 million tons, or 750 million barrels of oil.

Jan 1, 1985

S.L. Barua and Y.C. Kim M. Armstrong's paper is very interesting and can be regarded as a pioneering work of applying geostatistics on washed coal. The density levels used in her study are uniformly spaced, which facilitated curve fitting through a proper experimental design. Most of the existing coal washing plants in the US, however, gather washability data at non-uniform intervals which, in turn, affects the goodness of curve fitting. We would like to emphasize the importance of having a proper experimental design, if a similar geostatistical application is to be conducted on washed coal. We, at the University of Arizona, tried the variogram on recovery (Kim, Barua, and Baafi, 1982, SME preprint 82-143) which showed a similar pattern as Fig. 4 of Armstrong's paper. In both cases, the first experimental variogram value is invariably and inexplicably higher than the second variogram value. Although Armstrong ignores the first point because of "small number of sample points," we did not do so because there were 17 sample pairs. As a consequence, we concluded that the obtained experimental variogram was unsatisfactory and that further research is warranted. In other words, this disagreement in variogram interpretation between M. Armstrong and the University of Arizona begs the question whether the experimental variogram of Fig. 4 truly reflects the spatial correlation in washed coal, assuming there is such a correlation. Finally, we wish that Armstrong could have done a similar study on clean sulfur, which is a vital interest to the coal mines in the US. Her implied remark on sulfur in the concluding section of the paper may turn out to be incorrect because our experimental variograms on clean sulfur at different density levels were even less satisfactory than those on recovery.

Jan 1, 1985

By J. P. Hansen

The Bureau of Mines has investigated the S02 leaching of MgO from high-MgO-bearing Florida phosphate concentrates. The S02 was effective in leaching some of the MgO from three phosphate concentrates; flow rate of the S02 and leach time were major factors in determining the amount of MgO leached. Calcining the samples, then grinding to minus 200 mesh, and elevating the leach temperature gave only small increases in the amount of MgO leached. The research also showed that some of the MgO was so intimately associated with the phosphate mineral that it could not be removed by S02 leaching. This amounted to about 0.6, 0.7, and 1.0 pct MgO in three leached residues. The calculated heads for the three concentrate samples averaged 1.4, 1.1, and 1.5 pct MgO, respectively, before leaching.

Jan 1, 1985

By Wallace W. Roepke

Research to evaluate the lubricity effects achieved by spraying water on the cutting bit of a mining machine or spraying water on the coal during cutting has shown that neither practice affects cutting forces, as had been believed. However, when water was supplied to the cutting zone axially through the bit at 3,000 to 5,000 psi pressure, tangent'ial cutting forces were reduced an average of 30 pct at a I-in depth of cut while normal bit forces were reduced an average of 65 pct. Lower normal forces mean reduced bit wear, faster advance with greater depth of cut, and fewer coal fines.

Jan 1, 1985

A laminar-flow furnace technique was used to study the combustion of 37-53 µm size fraction of Woodlawn copper concentrate containing 7.4 per cent zinc, 5.0 per cent lead and 22.5 per cent copper. Factors studied included the effect of time, temperature and the distribution of volatile elements between the panicles and the fume. Air was used for most of the work but a few tests were carried out using 1 per cent oxygen in nitrogen. Chemical analysis, X-ray diffraction, and scanning electron and optical microscopy of polished sections were used to characterize the reaction products.When the concentrate was combusted at low temperatures (800-900°C), the fume was rich in lead. At higher temperatures, this was diluled by increasing amounts of zinc and copper. 70 per cent of the zinc, 60 per cent of the lead and 40 per cent of the copper were found in the fume after oxidation at 1400°C. Lead, zinc and copper were present in the fume as anglesite (PbSO4), zincite (ZnO) and cuprite (Cu2O) respectively. The major phases present in the panicles were magnetite (Fe3O4) and/or cuprospinel (CuFe2O4), with some zincite and cuprite.Elemental copper was found in the particles oxidized in 1 per cent oxygen. Possible vapour species responsible for the vaporization are discussed.

Jan 1, 1985

By Stuedel J

Starting from comprehensive programme systems for monitoring tasks of any kind, this paper follows the steps of the programme system hierarchy from top to bottom. The monitoring and control centres for entire production units, the subordinate centres, i.e. district control centres, the microcomputer based autonomous control systems, and data input by mobile terminals are discussed. To an increasing extent, the main emphasis is shifted from monitoring and control of individual machinery to optimized operation of extremely complex comprehensive systems. Network displays, for instance displays of production, transport, supply- and evacuation-networks as well as of safety systems, gain increasing importance. Personnel deployment systemsand planning networks as well as stocktaking and accounting are more and more closely linked with the above-mentioned networks. In order to keep development and application (purchasing) costs low, and to assure compatibility, the use of standard modules is to be assigned particular importance. New module developments are introduced, and the design of standard interfaces for computer and module coupling are discussed.For conclusion, a short view is given on the opinion of the line manage-ments on how future hierarchic systems should be featured in terms of individual units and overall systems, and used.

Jan 1, 1985

By D. C. Rance

"The Quintette Coal Limited property is located in the north east coal area of British Columbia. A basic agreement with the Japanese steel industry was ex ecuted on January 27, 1981 for the sale of 69.5 million tonnes of Quintette metallurgical coal over a 14.5-year period. This contract period can be extended by Jive years by mutual agree ment. Sale agreements have also been signed for the sale of 19.4 million tonnes of oxidized coal over a 15-year period. Work started on site development in the late summer of 1981, and at present, two of the four eventual pits-the McConkey and Frame-are under development. The pits are currently in a pres/ripping phase. These pits are notable for the stripping volumes that have to be removed from relatively small pit areas. in order to provide for the required detailed rapid short-range planning of these pits, engineering will be computerized, as will the truck dispatch system. The mining area lies 21.1 km from the plant site by road and the transport of raw coal LO the plant is by means of a highspeed conveyor system which has a total length of 13.4 km with a vertical drop of 740 m. The surface plant facility was designed on a modularized basis to facilitate maintenance, and is designed to enable the use ofgravity flow ofraw coal and heavy media in the plant to minimize the use of pumps. The construction of the plant and mine site facilities is on-going, and the first coal production is scheduled for early December 1983. Introduction Quintette Coal Limited is a Canadian company incorporated in the province of British Columbia in 1971. Denison Mines Limited is the manager of Quintette's activities. Equity in Quintette Coal Limited is held by several shareholders, with interests as follows: Denison Mines 'Limited, 500Jo; Charbonnages de France International S.A., 120Jo; and Japanese interest, 38%. The project will develop almost 120 million tonnes of coal for marketing during its first 20 years of production. All of the planned production tonnage has been committed to Japanese markets. Most of the coal will be metallurgical grade, and the remainder will be a high-quality thermal coal. The Mcconkey and Frame pits, which will initially provide the mine's production, will commence production in early December 1983 and will, in 1985, reach the full annual production of 5 million tonnes clean metallurgical coal and 1,380,000 tonnes of clean thermal coal."

Jan 1, 1985

By S. C. Termes

To help develop the basis for new fine-particle separation methods, the Bureau of Mines has investigated the use of cross-linked starches containing four chelating groups--carboxylate, iminodiacetate, dietha-nolamine, and xanthate--as flocculants for selected metal oxide and hydroxide mineral fines. It was found that those starches capable of interacting with the mineral surface by a chemisorpti,on mechanism (as indicated by zeta potential measurements) produced the highest recover-ies and'grades of the metal oxide or hydroxide when flocculated from a binary mixture with quartz. The effects of pH, dispersing agent, stirring rate, stirring time, and starch dosage on selective flocculation were studied for binary mixtures of hematite and chromite with quartz. Floc strength becomes important in achieving maximum recoveries by mechanical postflocculation separations.

Jan 1, 1985

The Morley Coal Measures (Upper Cretaceous) at Ohai Coalfield were deposited in an intermontane basin alluvial environment of entirely terrestrial aspect. Within this regional setting, three distinct types of depositional environment are recognised; these are: (i) a sand-dominated (South Saskatchewan type) braided river system characterized by channel-bed dunes and possibly compound bars; (ii) a well-drained floodplain environment frequently subject to crevasse-splay and overbank-flow sedimentation; and (iii) a poorly-drained, commonly peat-accumulating backswamp environment locally traversed by tributary drainage systems and occasionally inundated by crevasse splays and overbank flows. All major coal seams of the Morley Coal Measures originated within forest moors under predominantly telmatic (periodically inundated) conditions. The peat-forming vegetation comprised largely arborescent forms (dominantly conifers), in addition to pteridophytes and bryophytes. In-seam vertical variations in coal type indicate groundwater levels initially decreased and then increased during the lifetime of a particular peat swamp, possibly in response to a change in the migration direction of an adjacent fluvial system. The proposed depositional model for the Morley Coal Measures has the potential to be utilised during exploration programmes and mine development to impart greater objectivity to predictions concerning seam geometry and continuity, trends in coal type and quality, and likely roof and floor conditions.

Jan 1, 1985

By R. V. Ramani

This volume is the first of a four-volume final report on research carried out under a contract from the U.S. Bureau of Mines on the development of a computer simulation model for surface mine reclamation planning. The other volumes are titled as follows: Volume II: Dragline Model, Volume III: Mine Coordinate Generator System, and Volume IV: User's Manual for OPMHS/2. This report deals with the development of a geological model for surface mine planning. The most common orebody modeling techniques are described. A brief review of geostatistical theory and concepts is presented. A geostatistical option for orebody modeling is developed and validated. Computer programs and sample outputs are appended.

Jan 1, 1985

By C. E. Brechtel

This project describes the design and testing of large face ventilation systems for oil shale mining. A design data base was generated by reviewing general industry practice, oil shale industry planning, and technical literature. Conceptual designs for seven different systems were developed and evaluated for suitability. A large, free-standing, jet fan and reversible fan with rigid duct were selected for fabrication and testing. The two systems were field tested in a dead-end heading 55 ft wide by 30 ft high and 320 ft long. System performance was optimized using measurements of air flow direction and air velocity. Total system performance was then measured using SF6 tracer gas released to simulate blast fumes, hot diesel exhaust, methane layering and methane from a blasted muckpile. Field testing indicated that both systems delivered similar performance. The jet fan offered some clear advantages because of its mobility, ease of oper-ation and lower power requirement. It also offered some functional advantages in ventilating for methane because of it high average velocity.

Jan 1, 1985

By William W. Aljoe

This report summarizes the Bureau of Mines noise-control research program from 1972 to 1982. Each segment of the mining industry--under- ground coal, underground hardrock, surface mining, and processing plants--has different noise-control problems because of vast differences in working procedures, equipment, and workplace design. The Bureau has identified the most serious noise problems in each segment and has developed strategies for attacking these problems. This publication points out the need for noise control in the mining industry, discusses Federal regulations governing worker exposure to noise, and describes the Bureau's overall approach to mining noise- control research. It traces the history of noise overexposure in each segment of the mining industry and discusses the major noise sources. It provides detailed information on noise-control research efforts in the Bureau's major areas of emphasis, including the results of these efforts. Finally, the report discusses the Bureau's future role in research on mining noise control, emphasizing the need to expend more effort on long term in-house investigations into the noise problems that have been identified in past programs as the most serious ones.

Jan 1, 1985

By W. L. Cooley

A significantly different method of evaluating mine ground system safety is investigated. The method measures touch and step potentials around ground beds and grounded equipment resulting from a series of extremely small simulated faults. The values are then scaled for a full-scale fault. The method should be particularly useful for large ground beds and under conditions where the ground bed cannot be isolated from the rest of the ground system in order to make traditional ground bed resistance measurements. Instrumentation for making the alternative measurements is evaluated under rigorous field conditions. A step-by-step procedure is proposed for evaluating a surface mine ground system. This procedure was subject to several field tests at eastern metal/non-metal mines. The final evaluation procedure is written as a stand-alone document for use by MSHA inspectors and mine operating personnel, and is included as an appendix to the report. The authors conclude that the procedure is effective in evaluating ground system safety and recommend that it be further evaluated in the field.

Jan 1, 1985

The contract objective was to evaluate sources of airborne quartz and research control methods that would assist underground mine operators in complying with respirable dust standards which have been reduced because of quartz in the dust exceeding five percent. The work involved: Phase I -evaluate sources of quartz dust at the roof bolter work location; Phase II -evaluate the relationship between the quartz content of the coal and adjoining rock strata and quartz exposure at the roof bolter and continuous miner locations Phase III -conduct laboratory tests to determine performance parameters for roof bolter dust collector systems. The underground surveys for Phases I and II determined: (1) the continuous miner typically is the greatest source of quartz exposure for the miner and roof bolter operators when single-split ventilation is utilized, (2) a statistically significant relationship be­tween quartz content in face material and operator exposure was not determined and data suggested mining equipment and procedures may be more critical. The Phase III lab tests indicated the use of dust hog-type bits, filter cartridges, maximized collector airflow, and reduced bit rpm should be utilized to minimize dust liberation at the roof bolter.

Jan 1, 1985