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By N. T. Rempe

Proper use of natural resources is multiple use. Underground space resulting from mineral extraction offers opportunities for deep geologic waste disposal (DGWD) which can solve many environmental problems. U.S. government projects plan to use specially mined excavations to dispose of radiotoxic and mixed waste. DGWD takes careful planning, technology transfer, and true partnership between waste generators and mine/repository operators. Using the experience, accumulated by domestic projects in preparation, and by foreign repositories in operation, U.S. mines can claim their rightful share of the growing market for DGWD.

Jan 1, 1996

By P. M. Krishna

An example illustrates the use of ASTM Standard E901-82, Classification System for Uranium Resources. The example demonstrates the dynamic nature of the process of classification and attests to the necessity of addressing both the aggregate needs of broad-scale resource planning and the specific needs of individual property evaluation. Problems that ,remain in fixing the classification of a given uranium resource include the uncertainty in estimating the quantity of undiscovered resources and resolving the differences that may exist in deciding when the drill-hole spacing is adequate to determine the tonnage and grade of discovered resources.

Jan 1, 1983

By J. D. Miller

Pilot-scale tests indicate that effec¬tive concentration of fine gold from Colorado River sands can be achieved by flotation with the air-sparged hydrocyclone. The fine sands (55% minus 400 mesh and 0.01 opt*) from gravity concen¬tration were processed with a 5-cm air-sparged hydrocyclone (capacity -1.0 tph dry solids). Concentrate grades as high as 5.0 opt were produced in a single stage at a recovery of 75.0%. The separation efficiency was significantly better than that achieved in conventional batch flotation experiments.

Jan 1, 1985

By P. W. Hunter

The construction of a major sewerage scheme requiring 15.3 km of 5.5m excavated diameter tunnel in basalt, mixed and soft ground has been undertaken by the Melbourne and Metropolitan Board of Works. A double shielded Tunnel Boring Machine was selected to excavate 13.7 km of basalt and mixed ground. Advanced methods for recording operational data on the TBM were introduced. Progress to date has shown that the TBM can excavate rock very effectively with a best weekly production of 178.8m; soft ground has been encountered and successfully handled.

Jan 1, 1987

By N. Edmonson

The demand for sulfur divides into two major categories: agricultural and industrial. Most of the agricultural demand is related to the production of phosphate fertilizer products. Industrial demand is derived from the demands for a large number of products and is related to a variety of industrial processes, no one of which characterizes it in a simple way.

Jan 1, 1994

By Edgar O. McAlister

Associated with cordilleran intrusives of intemediate to acidic composition, gold/silver ores are generally found in the intruded host rocks which are adjacent to these intrusives. Generally precious metal deposits lie further from the intrusives than allied base metal deposits. For vented intrusives, the associated volcanics may constitute the intruded rock and form the host for precious metal accumulation. Potential field methods, particularly magnetics, can help to define unseen boundaries of intrusive systems and thus can point to generalized prospecting targets. Other clues arise from the intrusive system type, its emplacement fracturing, the host rock type and local magnetic changes caused by mineralization processes.

Jan 1, 1984

Underground instrumentation and observations at longwall panels have demonstrated that the growth of main roof causes an extremely high roof weighting on the shields. It can sometimes result in catastrophic effects on the support when the roof weighting intensity far exceeds the support capacity. In this paper, a comprehensive study was conducted on characteristics of main roof breakage and its effects on shields at different locations, based on the monitored shield data, theoretical analysis, and finite element analysis. With the help of theoretical analysis and numerical modeling, stress distribution and redistribution in the main roof were analyzed in detail to define main roof failure modes and understand the maximum roof weighting intensity imposed on the shields. From this study, it was found that the effects of main roof breakage on shields are chiefly related to the shield initial setting condition and the final failure mode of the main roof.

Jan 1, 1994

By L. Alan Weakly

The U.S. Department of Energy (DOE) has entered into a $l.5 million Cooperative Agreement with Alpine Equipment Corporation/Astro International Corporation ("Alpine") of State College, Pennsylvania, for the evaluation of water-jet-assisted (WJA) mechanical cutting of oil shale under actual mining conditions. A commercial-sized, heavy WJA mechanical miner is being assembled based upon the successful "factory testing" of a smaller prototype miner utilizing standard tungsten-carbide and Polycrystalline Diamond Composite (POC) bits in large oil shale boulders. Actual field testing of the machine will be conducted in an oil shale mine located in the Piceance Basin of Western Colorado. In-mine logistical support is being provided by several oil shale companies through the Colorado Mining Association (CMA) and the U.S. Bureau of Mines (USBM).

Jan 1, 1990

By C. E. Schmidt

Homestake crushing and grinding, practice-was completely revised during the period of 1951-1953. During the conversion, both crushing plants at the head frames the Ross and the Yates, were changes at each plant involved replacing the two 8K gyratories with a rebuilt, The flow sheet single thirty inch gyratory for primary crushing to four inch. The gyratory discharges to a seven foot Symons standard cone crusher set at 1-1/8 inch opening. The cone discharge goes to Tyrock screens fed by vibrating feeders. Screen openings, are l/2 inch by 5 inches: at the Ross. Plant, and 3/8 inch by 5; inches at the Yates. Screen oversize goes to a seven foot Symons cone brusher converted to the short head type; the crusher setting is 5/16 inch. Crusher, discharge; is closed circuited with the Tyrock screens, The above crushing installation delivers a minus 5/8 inch rod mill feed to the mill bins. The crushing revision eliminated the-180 heavy South African type stamps, which had previously reduced the 2 inch crushing plant product to a minus 5/8 inch feed for the 10 rod mills, and 8 ball and pebble.; mills, other revisions in the mill flow sheet, resulted in 3 identical units of about 1350 tons per day, capacity per unit, Each unit consists of an open, circuit 6 foot by 12 foot rod mill, fed from two 24 in by 48 inch vibrating feeders of the four feeders available per unit. A gathering belt delivers the ore discharge of the feeders to the Transportoweigher, which in turn discharge s, into the rod; mill feed spout. Rod Mill discharge is the feed for the 9 foot by 11 foot ball mill, The ball mill is closed circuited with a 16 foot by 30 foot Dorr Classifier. The Homestake make amalgamator, for coarse gold recovery in the ball mill circuit, made' necessary a 36 inch spiral conveyor between the classifier rake discharge and, the combination drum and double scoop feeder on the ball mill See Figure l - the flow sheet of the two stage grinding units.

Jan 1, 1958

By W. Holding

Since the 1975 International Mine Ventilation Congress in Johannesburg there has been a trend in South Africa towards making the mine ventilation departments responsible for monitoring the total environment. This includes the taking of noise and illumination measurements and there is in fact a debate taking place as to whether the departmental title should be changed to 'Environmental Control Department'. The organisers of the 2nd international Mine Ventilation Congress have decided that noise and illumination will not be included as Congress subjects and 'Total Environment' includes only those facets which are open to debate at the Congress. The choice of mine is significant in that while most Congress papers from South Africa will be devoted either to coal mining or to the somewhat unique deep level gold mines, Prieska Copper Mine is a mine which can easily be identified with similar mines in many other parts of the world. The mine is situated some 750 km south west of Johannesburg and about 600 km north east of Cape Town. Current production (ore and waste) is about 340 000 tons per month and the total underground labour force is just over 2 000. The ore body is a massive sulphide, the main minerals being copper and zinc and the method of mining is sub-level open stoping. Daily average surface temperature conditions range from 85°F (29.5°C) dry bulb and 69.8°F (21°C) wet bulb in mid-summer to 42°F (5.5°C) dry bulb and 36.5°F (2.5°C) wet bulb in mid winter. The information presented in-this paper is limited to what can be gathered by mine ventilation staff as part of an on-going exercise and is obviously not as comprehensive as would be the case if a fully equipped research establishment were to become involved. The paper will be divided into three sections 1) Gases 2) Dust 3) Heat In each section statutory and/or other standards will be set down followed by a discussion of assessment and in some cases control methods.

Jan 1, 1980

By Ernest A. Draeger, James W. Collins

Water only cyclones, sometimes referred to as hydrocyclones, are one of the newest types of coal processing equipment. These devices have achieved wide acceptance as fine coal cleaners in the past decade. Many metallurgical coal plants employ water only cyclones to process 0.5 mm x 0 size coal. Some of these plants have as many as 40 to 50 305-mm-diam units with each unit receiving as much as 9 t/h of raw feed. The growth in the utilization of hydrocyclones is due partly to the energy shortage, partly to the general increase in over-all coal preparation, and also because of a need for a simplified fine coal (0.5 mm x 0 size) gravimetric separator. Large diameter water only cyclones are also available and in use to process feed sizes up to 32 mm in size. However, the size normally employed for cleaning 0.5 mm x 0 coal are 356 mm or 305-mm-diam for single-stage circuits. In two-stage circuits, the secondary units are normally the same diameter as the primary units or smaller, such as 203-mm-diam. By using the small diameter cyclones and treating a closely sized feed, 0.5 mm x 0 only, it has been found that the probable error or imperfection of the water only cyclones is comparable to that obtained on the same size fraction treated in a large 610-mm-diam heavy media cyclone washing 38 mm x 0. The water only cyclone can approach the efficiency of a heavy media cyclone when cleaning fine solids because it creates its own dense media by accumulating high specific gravity particles in the wide angle conical section of the cyclone. A cut-away cross sectional view of a water only cyclone is shown in Fig. 1. It is also true that when treating a wide range of sizes (38 mm x 0) in heavy media cyclones, the smaller size particles (0.5 mm x 0) separate in proportion to the split of the media through the cyclone rather than by particle density.

Jan 8, 1980

By Diler Katircioglu-Bayel

This study aims to investigate the effect of combined mechanical and ultrasonic milling on the size reduction of talc. First, the talc sample was wet-ground in a stirred media mill for five different lengths of time (30, 60, 90, 120 and 150 min), and the optimum result was subsequently achieved with treatment by ultrasonication. The effects of amplitude (20, 35 and 50 µm), solid ratio (2.5, 5, 7.5 and 10 percent), and sonication time (60, 120 and 240 min) on the sizes of the final product were investigated. The pre-milling by wet grinding caused a decrease in the grinding resistance of talc. Sequential ultrasonic treatment, which was applied to the talc sample, generated smaller particles in comparison to those acquired by stirred media milling alone. Experimental results were assessed based on the product particle size (d10, d50 ), reduction ratio and specific energy consumption. Submicron particles prepared by ultrasonic treatment were highly stable compared to stirred media milling alone as investigated in terms of particle size. In addition, the effects of mechanical and ultrasonic milling on the structural properties of talc particles were characterized by X-ray diffraction (XRD) analysis.

Stillwater Mining Company (SMC) has an extensive history with tunnel boring machines (TBM) at the Stillwater and East Boulder underground PGM mines in Montana. The most recent TBM used is for the Blitz Project, where a 5.5m (18ft) diameter main beam unit, commissioned in Q3 2012, is being utilized to drive a 6,975m (22,500 ft) ventilation and haulage level East of the Stillwater Mine for the Blitz expansion project. The assembly/commissioning of the TBM, institution of the planned diamond drilling program, application of ground control systems, and the current tunneling metrics will be covered.

Feb 23, 2014

By Edward C. Heistermann

The Falkirk Mining Company, a wholly owned subsidiary of The North American Coal Corporation, is located 80 kilometers (50 miles) north of Bismarck, North Dakota. Falkirk is under contract to provide 5.08 mil- lion tonnes (5.6 million short tons) annually to the Coal Creek Generating Station, an 1100 mega- watt electric plant owned by the Cooperative and United Power Associations of Minnesota. Coal Creek is located 2.4 kilometers (1 ½ miles) south of the Mine. Electricity from the plant is transmitted to rural electric customers in Minnesota via a 400-kilovolt D.C. power line.

Jan 1, 1982

By Neil D. Donnell, O&apos

Ore reserve estimation at the Syncrude Canada Ltd. open-pit oil sands mine in Northern Alberta has evolved since the project's inception. Early techniques followed a conventional petroleum reservoir analysis format, with relatively widely-spaced drill holes and semiquantitative grade data. Experience has developed a more standard mining approach, including classification of geological materials by both lithology and sedimentary origin, timely and multi-purpose drill holes, precise analytical data, empirical recovery factors, a computerized geological data base, and an ore body block model. Future efforts will involve enhancement of existing techniques, use of geostatistical algorithms, quantification of confidence limits, and improved control of the ore model by geological parameters.

Jan 1, 1985

By Richard B. Jacob

The High Gradient Magnetic Separator (HGMS), also known as the High Gradient Magnetic Filter (HGMF), is an effective device utilized in magnetic separation. This method of separation is gaining popularity in the separation of sub-micron material containing feebly magnetics. The most common use of this type of separator is in the removal of iron stained particles to improve the brightness of kaolin clay. Potential areas for use of this magnet include: (1) desulfurization of coal (2) the clean-up of mill effluent (3) removal of fine particulate matter from municipal and industrial waste (4) desulfurization of oil

Jan 1, 1983

By Jacques B. Wertz

It is well known that the major fractures and lineaments presently recorded in Western North America are preferentially oriented along a general northwest direction (Figure 1). There are other features, however, more subtle, more elusive as a rule and which can only be inferred, occurring at right angle to this broad NW direction. It is intended a) to examine some of these NE or transverse trends, b) to compare these regional NE breaks to similar ones that transversally cut through the eastern part of the European Tethys, more specifically in Iran and Turkey, and c) to study their potential relationship to mineralization in both areas.

Jan 1, 1973

By Alfredo Menendez, Alberto Sarmentero

A B S T R A C T The Los Pijiguaos bauxite is one of the largest accumulations of trihydrate alumina ore recently discovered; it is a plateau type, with no overburden, relatively soft tertiary quartz-bearing bauxite developed on a pre-Cambrian Rapakivi Granite batholith. The deposits are found in the northwestern rim of the Guiana Shield, State of Bolivar, Venezuela, and were discovered in 1976 after a grass-roots exploration campaign. Target areas were mainly selected on the basis of geological and geo¬morpholigcal criteria, guided by correlation with known deposits elsewhere in the Guiana Shield. The vertical. lateritic profile consists of an upper concretionary zone, followed by a mottled zone, a palid zone and finally the weathered rock merging into fresh granite. The upper concretionary zone displays a cellular, pisolitic or spongy texture and contains the following minerals: gibbsite (60-90%),quartz (5-10%), hematite (5-10%), goethite (under 5%), boehmite (traces), kaolinite (traces). The gibbsite content decreases sharply downward from the lower limit of the concretionary zone and the kaolinite and quartz content increases in the underlying mottled zone. The mottled and palid zones display a pseudo rapakivi texture and quartz, kaolinite and mica are the. essential minerals.

Jan 1, 1984

By Błażej Doroszuk, Robert Król

Mill drums are essential equipment in various industries for the comminution of materials. To optimize their design and operation for efficient and cost-effective processing, it is necessary to understand the behavior of the mill drum under various operating conditions. This study investigates the behavior of a mill drum using a combination of experimental and numerical methods. The factors that can influence the behavior of the mill drum, such as the size and shape of the mill, grinding media, rotational speed, filling level, and material properties, are discussed. Experimental methods can be limited in obtaining measurements of internal processes, so numerical methods such as the Discrete Element Method (DEM) are also used to simulate the behavior of the mill drum. In this study, the experimental measurements of the motion of the grinding media are obtained using computer vision methods, and the numerical simulations are calibrated using the experimental results. A designed experiment approach is used to evaluate the performance of the mill drum under various operating conditions. The results of this study can be useful for the design and optimization of mill drums to achieve better performance and energy efficiency.

Jun 25, 2023

By Yoginder P. Chugh

Effects of moisture absorption on the behavior of the Dykersburg shale overlying Harrisburg coal seam in Southern Illinois are presented in this paper. Cylindrical samples of the shale 2.5 cm in diameter and 5.0 cm long were studied for weight gain and swelling strains at 90, 95, and 100 percent relative humidity and under immersed water conditions. After attaining equilibrium conditions, the samples were studied for changes in the strength and deformation behavior. The depth of moisture penetration was measured using the Vickers microhardness measurements. Using the basic mass transfer concepts, effective diffusion coefficients were computed for the shale.

Jan 1, 1980