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By F. F. Aplan, C. E. Raleigh

Three run-of-mine bituminous coals, ranging in rank from low volatile to high volatile A, were floated at nominal -28 mesh (590 µm), -100 mesh (150 µm), and -400 mesh (37µm) feed particle sizes with selected pyrite depressants and a dispersant. For the three coals tested, pyrite and ash -forming minerals were usually rejected best at -100 mesh feed particle size. Depressant additions tended to improve flotation selectivity between pyrite and coal. When joint dispersant-depressant systems were used at -100 mesh (150 µm) feed particle sizes, the total sulfur content of the clean coal decreased further. For a comparable coal yield, less fuel oil collector was required for the flotation of -100 mesh coal than was required for the flotation of either -28 or -400 mesh feed.

Jan 1, 1992

By Salt Lake City Research Center, D. G. Foot, J. D. McKay

As part of its research program on column flotation, the Bureau of Mines, Salt Lake City Research Center has performed studies on (1) column flotation amenability and comparison with conventional flotation results for over 15 mineral systems, (2) alternative methods for improving column bubble generation systems, (3) mineral behavior within a column, and (4) the effect of changes in column operating parameters on flotation grade and recovery. Based on results from these studies, flotation columns (1) are capable of producing higher grade concentrates in fewer stages than conventional flotation cells at equivalent or increased recoveries, (2) require less retention time than conventional flotation cells, and (3) can be divided into cleaning and collection zones that have characteristic mineral-upgrading-per-foot values. Attempts to improve the column air sparger have led to the development of a superior external bubble generation system, which can (1) achieve increased air holdups. (2) produce bubbles from 400 Um to 4,000 Um average bubble diameter with minimal frother addition, (3) provide superior bubble size control, and (4) be maintained without column shutdown. Efforts are continuing to improve column flotation and transfer successful technology to industry.

Jan 1, 1988

By G. Newman, C. D. Sellars, E. A. Portfors

Power for mine operation in remote locations is usually provided by diesel generators. For gold mines where processing is normally desirable on-site, power requirements can be significant and the operating cost for diesel generation then becomes an important factor in mine feasibility. If a suitable site is available, a small hydroelectric power facility near the minesite can provide a significant portion of the mine power requirements. The hydrological, engineering and economic factors involved in small hydroelectric power development are described in this paper. Capital costs are minimized by run-of-river hydro development which does not require a dam and reservoir and has less environmental impact. During periods of low flow, diesel generators are used to make up the power demand. The hydrologic analysis required to determine unit energy costs is described and technical requirements for linking the hydroelectric power facility with diesel generation are outlined. Case studies are presented demonstrating the economic advantages of a small hydro installation. One case study is for a proposed gold mine in British Columbia and the second is a large operating gold mine overseas, for which the hydroelectric power scheme is presently under construction .

Jan 1, 1987

By S. S. Peng, Luo. Y.

In a shearer longwall mining operation, the longwall hits are responsible for breaking into and chipping the broken coal blocks away from the coal face. However, underground observations found that the bits being used were working under various degrees of wear. This wear can be reduced by using better-designed longwall bits and by properly selecting shearer operating parameters. A computer program was developed to simulate the performance of the longwall bits. The information required by the program are the shape of the bit head, the installation of the bits on the drum and the operation parameters. Through the simulations, the main factors affecting the bit-wearing process are identified. Suggestions are also made for improving the design of the longwall bits.

Jan 1, 1998

By W. E. Foreman, A. Hayatdavoudi, A. Ghalambor

The objective of this investigation was to determine the sensitivity of three selected input parameters in the operational control of continuous bottom fed thickeners used for the treatment of coal refuse slurries. The three variable parameters were "Feed Flow Rate," "Feed pH," and "Feed Solids Concentration." These three input parameters were studied under three cationic-anionic polymeric conditions. For each polymeric condition, two mathematical models were developed, one for overflow response and the other for underflow response. The combination polymers produced the best quality of overflow and underflow. For this polymeric condition, change in the feed solids concentration was the most sensitive factor in the maintenance of the overflow quality, and the feed pH was the most sensitive factor for the maintenance of underflow quality. The mathematical models generated a set of plots that would allow an operator to control and/or adjust any of the three variables to achieve optimum conditions.

Jan 1, 1991

By Terry Ritzel

Predictive maintenance technologies include vibration analysis, tribology, infrared thermography, ultrasonic detection and electrical measurements. These technologies have been applied to large electric mining shovels at the Cyprus Sierrita Mine outside of Tucson, AZ. The predictive maintenance program was initiated on the P&H models 2300 and 4100 electric shovels during August 1996. Results of these technologies have shown the potential for improving electric min- ing shovel availability and minimizing maintenance costs. Predictive technologies provide the tools to assess machinery condition. Availability is enhanced by the condition-based planning of component replacement. Maintenance costs are minimized by focusing resources through condition-based prioritization.

Jan 1, 1997

By D. W. Park

The Longwall Strata-Control and Maintenance System (LoSCo-MS) is a software and data-communication system developed at the University of Alabama. This system integrates real-time shield monitoring, data presentation, analysis and the forecasting of forthcoming events. The main objective of this system is to provide stability information on longwall panels, including excessive shield load, low setting pressure, leg leakage, poor shield performance and imminent maintenance problems. Analyses of various mining and geological parameters were also performed to determine past and present roof characteristics and to forecast roof loading patterns for the following mining cycles, the next periodic weighting, etc. A local coal mine in the Warrior Coal Basin has adopted this system to provide daily evaluation of ground stability and maintenance problems in their longwall panels. Two years of experience with this system is covered in this paper.

Jan 1, 2000

By R. L. Garrett

The quality of mineral additives used in a drilling fluid (mud) can dramatically affect the fluid's properties and the overall cost of drilling an oil or gas well. The principally wed minerals are bentonite, barite, barite/hematite blends, and hematite alone. The high specific gravity minerals, barite and hematite, are used to increase drilling fluid density. Bentonite clay is used to increase drilling fluid viscosity and gel strength and to provide a low permeability filter cake. A multimillion dollar investment in a well and the safety of the personnel on the drilling rig can depend on how effectively these mud additives perform with other constituents in the mud. This paper points out effects caused by small amounts of certain carbonate and sulfide mineral impurities in barite or hematite and how polymeric extender additives in bentonites contribute to unpredictable behavior of a mud. Effects like these are the reason oil companies using these materials sometimes set their own quality standards beyond those already specified in APZ Spec. 13A. Also discussed in this paper are the current standardization activities of API Committee 13 on these minerals.

Jan 1, 1988

By Parris A. Lyew-Ayee

This paper is the first preliminary report on the bauxites and terra rossas of the Caribbean. It concentrates on the islands of the Greater Antilles, and for reference purposes the Yucatan Penin- sula is included. At this point, observations made in Jamaica, Haiti, and the Dominican Republic are compared with reported information on Puerto Rico, the Bahamas, Cuba, the Cayman Islands, and the Yucatan Peninsula with regard to occurrence, as well as physical, chemical, and mineralogical composition. From this, an attempt is made at classifying the types of bauxites in the Caribbean, indicating the best reserves estimates, and the process ability of these bauxites. Some suggestions are also provided to fuel the controversy over the likely source material(s) or origin of the Caribbean bauxites.

Jan 1, 1984

By George Bárdossy

Most of the bauxite deposits in Europe belong to the karst type. They are located mainly ill Southern Europe along the Mediterranean Sea and in the Ural Mountains. Lateritic bauxite deposits occur on the Russian Platform, in Poland, Northern Ireland and in Turkey. Tikhvin-type deposits arc found on the Russian Platform. Bauxite formation in Europe started in the Middle Devonian. The main bauxite forming period was the Upper Cretaceous. Very few bauxites are younger than Eocene. Most deposits are covered by overburden of up to 1000 m. Prospecting is carried out by drilling. Several geophysical methods are used to detect the hidden deposits. Geostatistical methods were introduced in several countries for evaluation of the reserves and the geometry of the deposits. Data on bauxite production are given for 1982 and since the beginning of mining in Europe.

Jan 1, 1984

Traditionally, production volume has been considered the major determinant of cost. As volume increases, total cost increases but unit cost decreases. This concept has been so widespread in industry that many of the tools used to analyze costs are based on production volume as the sole measure of activity and driver of unit cost-fixed and variable costs, cost-volume-price and breakeven analysis, contribution margin, flexible budgets, and others. Clearly, volume is a driver of cost. It is important in both a tactical sense (to the manager at an operating mine) and a strategic sense (as one determinant to the firm's overall cost position). However, many other factors influence costs as well, even though they have not been studied to the same extent. For example, production managers know that their costs will be reduced if the workforce does not have accidents. Safety costs are to a large extent independent of volume. Other cost components increase as volume increases, such as some environmental charges. Some costs may or may not reflect volume changes. Maintenance, for example, may appear as either a fixed or variable cost, as can operating labor in facilities that are highly automated. In the strategic sense, where the firm is selecting a strategy to pursue competitive advantage and increased profitability, all costs are variable. This reflects both the strategic intent and the long-term time frame associated with strategic positioning. Tactically, on a month-by-month basis, some costs are essentially fixed. Cost driver analysis must therefore consider the relevant time frame.

Jan 1, 1999

By Fathi Habashi

THE CHOICE of a precipitant for a certain metal ion depends, beside the economic factor. on the following factors: 1) The precipitant should be specific as far as possible so that pure precipitates can be obtained

Jan 1, 1970

By C. Ptacek, D. Hiller, J. L. Janbor, H. Mccreadie

Between 1991 and 1994, metallurgical residues from a pressure-oxidation autoclave at the Campbell Au-quartz mine at Red Lake, northern Ontario, were neutralized with dolomite-rich flotation tailings and were deposited in a polyethylene-lined disposal area. Mineralogical analysis indicates that most of the As occurs as a crystalline ferric sulfarsenate, and some is associated with Fe oxides and with K-H3O jarosite. Field pore-water geochemical data from 1994 and 1995 showed increases in Fe(II) and As(III) concentrations, suggesting that the sulfarsenate and jarosite are dissolving; none of the discrete As phases included in a thermodynamic database limit dissolved-As concentrations, and these concentrations may continue to increase. These results demonstrate the potential for Fe and As loading through groundwater systems.

Jan 1, 1998

By Steven H. Brown

Ore bodies which were once uneconomical to mine by conventional methods such as tunneling or open pits, have become attractive due to the development of nonconventional techniques, involving considerably less capital expenditure. Technologies such as uranium solution mining or in-situ leaching, have enabled commercial scale mining and milling of relatively small ore pockets of lower grade, and may make a significant contribution to overall U.S. uranium supplies during the next 20 years. Commercial size solution mining production facilities have operated since late 1975. Solution mining involves the pumping of ground water, fortified with oxidizing and complexing agents into an ore body, leaching and solubilizing the uranium in-situ, and then pumping the solutions to the surface where they are fed to a processing plant. Processing involves ion exchange, precipitation, calcining, and packaging operations. This paper presents an overview of the solution mining process and the health physics monitoring programs developed over the last four years at several production facilities as a result of the radiological character of these processes. Although many radiological aspects of the process are similar to that of conventional mills, conventional-type tailings as such are not generated. Some special monitoring considerations are presented which are required due to the manner in which radon gas is evolved in the process and the unique aspects of controlling solution flow patterns underground. An overview of the major aspects of the health physics compliance and monitoring programs that have been developed are discussed.

Jan 1, 1981

By Donald Ross-Watt

Mining project investment concerns the installation of mine capacity for the purpose of generating a stream of future economic benefits. In order to make this type of investment decision, the optimum specifications for the project must first be determined. Then, the economic justification of the investment tin be evaluated based on these specifications. Economic evaluation to guide mining project investment decisions is based on a proposed plan for mining the deposit over its operational life. If single point estimates are made of deposit characteristics and environmental parameters* as the basis for assessing a future stream of economic benefits associated with the investment, a future mining-plan can be optimally fitted to these estimates and, to the extent that such estimates are actually realized, this plan will retain optimality.

Jan 1, 1979

By B. J. Arnold, F. F. Aplan

A model incorporating rate and residence time to describe the froth flotation process was used to provide data for the evaluation of various kinetic flotation models and to provide scale-up information from laboratory to industrial scale coal froth flotation. Rate constants were determined in laboratory and plant froth flotation tests and the residence time distribution was measured for a bank of four 21 ft 3 (0.6 m3 ) WEMCO cells treating Upper Freeport seam coal and a bank of four 300 ft 3 (8.5 m3 ) cells treating Lower Kittanning seam coal. It was found that a lag time for continuous flotation should be incorporated into scale up models and that a kinetic froth factor ratio of between about 2.0 and 2.8 should also be used to scale up data from laboratory to plant scale.

Jan 1, 1989

By R. Candia

The use of industrial wastes, such as quarry fines of crushed stone, should represent a basic component of sustainable development indicators. Therefore, increasing investments should be foreseen in techniques of treatment and recycling of residues in mining, as well as by-product attainment that generate jobs and income. The standards of identification and discarding of industrial wastes vary significantly between countries. However, practically all nations have started becoming more restrictive regarding environmental legislation, especially concerning production, transport, treatment, recycling and final discarding of industrial wastes. Under an environmental point of view, solid wastes produced by a system (such as a quarry) can be handled in two ways: a) they can be discarded in piles or b) they can be internally or externally recycled and reused. This second practice is translated to an additional economic consequence such as an increase of income as well as a decreased environmental impact. This option is more advanced and should be included in company policy. This paper presents cases where this practice is used, i.e. diminishing the environmental liabilities through the use of the quarry fines in the manufacture of industrial devices, incorporating such wastes in the productive chain, instead of storing them in piles.

Jan 1, 2007

By Allan E. Hall

The use of full face boring machines in underground mining has increased considerably in recent years and over 200 raise-boring machines are now in use in the Western World. Several tunnel-boring machines have been tested notably in America, West Germany, Britain and South Africa. A relatively new concept is the blindhole borer, where the machine stands on the lower level and bores a full diameter raise upwards without the use of a pilot hole. Four of these machines have been tested to date in South African quartzites with varying degrees of success. The development of boring technology has created new problems for ventilation engineers and exacerbated several existing ones. This challenge has been met in many varying ways and this paper attempts to provide a review of the current state of the art. Technology and methods are developing at great speed in this field and therefore no final and absolute solutions can be proposed, since each machine and site pose individual problems which are best handled by local knowledge and experience.

Jan 1, 1980

By Slavoljub D. Maksimovic, Steve J. Page

The Bureau of Mines measured respirable dust emission rates from overburden drilling at a surface coal mine and the transport of this dust to downwind locations. The emission rates were estimated by using multiple gravimetric dust samplers mounted on a cross-shaped tripod located immediately downwind of the drill. The transport of this dust was measured at more distant downwind locations by a combination of respirable gravimetric sampling and integrated bag sampling of sulfur hexafluoride (SF6), which was used as a tracer gas. Two modes of sampling were used: (1) At five sampling locations arranged in a semicircle around the drill. The radius of this arc ranged from 15.85 m (52 ft) to 71.32 m (234 ft). (2) In-line sampling at downwind locations with samplers located at intervals of either 10.67 m (35 ft) or 15.24 m (50 ft) for a total distance of 76.20 m (250 ft). Samples were taken 1 .22 m to 1.52 m (4 to 5 ft) above ground level. Test results for the semicircular test arrangements showed that at any downwind location, the maximum contribution of respirable dust due specifically to the drilling operation was 42%; the average for eight tests was 13.6%. In general, there was no correlation between the downwind distance of this maximum contribution and the maximum contribution itself because of changing wind direction. Test results for the in-line arrangements indicated that the transport of the dust from the drilling operation usually decreases rapidly with distance and that, even though the drill dust may produce significant health hazards for the drill operator and drill helper (or other personnel in the immediate vicinity), the exposure of downwind personnel to drill-generated dust may not be a significant problem.

Jan 1, 1987

By C. J. Savage

Rio Tinto Minera, S.A. operates in Southern Spain, at one of the most ancient mining sites in the world, using advanced computerised mine planning. This paper describes the development and application of the mine planning systems to the copper and gold/silver operations. It briefly covers the hardware configuration, and the advantages and improvements in mine planning achieved. The system's application started with the long term mine planning of Cerro Colorado (open pit) copper mine and was gradually extended to cater for the medium and short term planning requirements of the other operations of the Company. The base of the system is a mineral inventory established by the combined use of the geology and geostatistical methods, and compatible with the mine planning requirements. The planning system has three major components: one used for open pit design and long term mine planning, another used for blast evaluation and finally one used for short term mine planning. Recently, a fourth component has been added to the system for reconciliation between predicted and actual tonnages and grades. There is common data file transfer throughout the system.

Jan 1, 1986