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By H. T. Kang

Various geological anomalies are encountered in underground longwall mines, and they cause stability problems. In this study, a number of detailed two-dimensional finite-element models were made, consisting of mine floor, roof, coal seam, shield structure, gob, etc. to analyze the influence of geological anomalies on longwall shields. Two different categories of anomalies were simulated. The first ones are shear zone and sandstone channels, with variable sizes and locations in the roof. The second category is fault or fracture plane, with variable friction factors, locations, and orientation of the fracture plane. The results of the analyses are' integrated with an artificial intelligence system for developing a forecasting guideline for prevention of underground hazards due to the existence of geological anomalies.

Jan 1, 1996

By K. W. Harris, K. A. Perry

Underground coal mines beneath Black Mountain in the Harlan County district of the Central Appalachian coalfields have an extensive history of bump events, which yields an elevated probability for significant injury or fatality to underground miners. According to Mark (2009), Harlan County has had the greatest concentration of deep-cover retreat mining in the United States. Combined with the extensive multiple seam mining history, room-and-pillar coal bumps have had a disproportionate impact on coal operations in this region. The Harlan seam, one of the principal, economically recoverable coalbeds exploited beneath Black Mountain, has a significant burst history that extends into modern times. A numerical investigation using the LaModel software of 17 bumps that occurred at the same mine in the Harlan seam was conducted and used to create a calibration methodology which serves as the quantitative basis for current and future numerical efforts in an adjacent mine exploiting the same reserve. In addition to this numerical study, a qualitative assessment of the geologic factors that are believed to contribute to the bump potential was completed. Combined with stability prediction using the numerical basis, these geologic factors will be used for recognition of high bump potential areas with the goal of reducing the potential for future bumps, helping to ensure the highest level of safety and productivity for underground personnel.

Jan 1, 2016

By Gealy W. Wallwork

The administrative processes of coal mines are becoming increasingly complex. As society evolves into a more complicated structure with greater emphasis on individuality, government regulations reach deeply into every activity in an effort to force individuals into a standardized mold. These contradictory pressures add an extra burden to the administration of a mining operation. Recent years have brought a substantial change in the skills needed by mine supervisors and managers. As a result, a better understanding of the administrative functions is necessary. The mine superintendent has the overall responsibility for the mine; for effective operation he must be sufficiently knowledgeable to oversee all the complex functions that make up the mine. This chapter does not cover all the administrative requirements because of the variation in mine operation and in company policies and organizational structure. It does attempt to identify the administrative functions that would be required at a large mine with a preparation plant. It is assumed that the mine operation is decentralized with very little duplication of functions at the organizational levels above the mine. Thus each function is assumed to be relatively complete at the mine and under the general supervision of the mine superintendent.

Jan 1, 1981

By S. S. Hsieh

As part of a program to address long-term needs for ensuring adequate supplies of domestic phosphate raw materials, the Tennessee Valley Authority (TVA) has conducted considerable research on dolomitic phosphate rock beneficiation. The discovery that alkyl diphosphonic acids act as phosphate mineral depressants led to the development of several processes involving a carbonate flotation step for the effective beneficiation of these problem ores. Most recently, a partial de-oiling process in which the reagent consumption is greatly reduced has been developed. The reduction is achieved because part of the initial feed is beneficiated without passing through the separate carbonate flotation step. Using this method, a phosphate product containing 30.6-30.9% P2O5 and 0.7-0.8% MgO was obtained from a Florida dolomitic phosphate pebble which contained about 23% P2O5 and 2.0% MgO. The P2O5 recovery was 80.8-86.5%.

Jan 1, 1989

By G. Davey

High speed stirred milling is a relatively new method of grinding in the metalliferous process industries. However it has been it has been in wide spread use in the industrial mineral field for over 30 years for various minerals. Many existing metallurgical operations are looking to maximize economic return from existing deposits, requiring new thinking and technologies. The operating experience of two existing copper operations will be covered to show the effect of the introduction of the Metso Stirred Media Detritor (SMD) a new type of high speed stirred mill. Both operations have derived significant metallurgical benefits from the introduction of this new technology. The benefits and process difficulties are covered and explained.

Jan 1, 2003

By D. Gove

Several coal mines in Southeastern United State face the problem of multiple, very thin coal seams or seams adhering to interburden, and because of the strip ratio economics, these seams must be recovered. Over the past few years several mines have discovered a common method to solving these problems...use of a Caterpillar RR-250 Road Reclaimer.

Jan 1, 1995

By Y. T. Auck, M. E. Kukura, L. G. Stevens

At its Technical Development Center in Tucson, Arizona, the UOP Mineral Sciences Division operates a completely integrated pilot plant testing a proprietary process for the extraction of nickel from limonite/saprolite ores. The process is based on the reductive roast- ammonia leach procedure now employed in several plants around the world. The process improvements are such that nickel extractions well above that experienced in these processes are possible, particularly on the more garnieritic/saprolitic ores. This paper will describe the process and the results of process development studies. The data show that pilot plant results confirm those obtained on the smaller laboratory and bench scales of experimentation.

Jan 1, 1979

By J. M. Avasthi

Gulf Research & Development Company conducted the nation's first underground coal gasification test in steeply dipping beds near Rawlins, Wyoming. The geotechnical considerations played a major role in the initial site selection. The test plan included a detailed geotechnical program for site evaluation, test design, permitting, and environmental studies before the burn. During burn, the geotechnical activity continued in the form of monitoring surface subsidence and acoustic emission. The postburn evaluation included studies of the drill cores obtained from the burn zone and effects on the surrounding rock mass.

Jan 1, 1981

By Victoria Vaccarezza, Corby Anderson

The demand for rare earth elements for everyday technology and applications has initiated much research into the extraction and recovery of these rare earth elements. An otherwise unknown group of minerals, eudialyte is a zircon silicate consisting of rare earth oxides (REO), contained in a unique mineral structure and represented by a complex chemical formula. Research into extraction and recovery of rare earth elements involves various beneficiation and hydrometallurgical techniques. The goal of beneficiation being to efficiently liberate and upgrade the REO content, followed by hydrometallurgy to extract the desired elements. This overview will discuss previous research on treating eudialyte group minerals via different mineral processing and extraction techniques.

By Xi Huang

The coal workers' pneumoconiosis (CWP) has been considered as the most serious health problem in the coal mining industry. The development of CWP in a worker lung depends on the average concentration and toxic components of the coal dust and the exposure length. Toxicity studies on coal dust shows the bio-available iron (BAI) in the coal dust plays an adverse role in the CWP development. It is also found that presence of calcite in the coal seams can significantly reduce the CWP cases as evidenced by the significant difference between the coal miners in the western and Appalachian coal regions. Based on this finding, it is proposed to artificially introduce calcite to BAI -containing coals in the effort to mitigate the CWP disease in coal industry. This paper introduces the scientific bases, the main geological factor that makes the differences, the proposed methods to introduce calcite to coal dust or to coal seams. Feasibility for the proposed methods is also discussed.

Jan 1, 2013

By Alex G. Sciulli

According to recent estimates, nearly 30 percent of the material from underground coal mining in the United States is rejected on the surface as waste. This accumulation of almost three billion tons of coarse and fine coal refuse is primarily from coal cleaning operations. The marketable coal is intermixed with sandstone, clays, shales, and carbonaceous rocks, which must be removed and disposed of in an acceptable manner. The disposal of mineral wastes is a major environmental concern. The most common types of environmental problems associated with coal refuse disposal are acid formation, erosion, and sediment control. Other areas of concern include air and water quality, combustion control, mine sealing, and reclamation. This paper focuses on these topics and attempts to outline special environmental features which can be incorporated into the design and construction of a coal refuse facility. Often these measures can minimize and possibly eliminate the potential environ- mental hazards. It is imperative, however, that these measures be adopted prior to and during construction, because of the relative ease and cost savings compared to post-construction implementation.

Jan 1, 1983

By A. D. S. Gillies

The effectiveness of coal mine face ventilation and the ability of air flow to maintain satisfactory methane and respirable dust levels in the working face area has been studied through the use of scale modeling techniques and underground testing procedures. In particular, consideration has been given to examination of the effects of operation of a high air flow machine mounted dust scrubber unit on face air patterns. Results obtained through a cooperative study with the Peabody Coal Company demonstrate that new mining cycles can be considered which increase production efficiency while maintaining satisfactory ventilation conditions.

Jan 1, 1982

By Leo J. Miller

Sulphur deposits occur within the upper Salado and Rustler gypsum beds. The formation of a sulphur ore deposit requires large quantities of oil and /or gas, which must find a permeable pathway into the gypsum beds. The Permian beds weathered for 90 million years in an arid environment prior to the advent of a more humid climate at the beginning of the Cretaceous Period. The first Cretaceous rivers enlarged the sinkholes and caverns of the Karstified Permian terrain and deposited coarse conglomerates and sands into the subsurface gypsum beds. The resulting network of caverns and sinkholes, filled with permeable sediments, permitted the free flow of hydrocarbons through gypsum. All sinkholes and caverns infilled with Cretaceous sediments that have penetrated beds of gypsum are associated with sulphur deposits. The Castile gypsum lies directly upon the oil bearing Bell Canyon formation. Sinkholes and caverns filled with Cretaceous sediments occur in the lower Castile. Biogenic calcite and sulphur are adjacent to these sediments. However, faults assume the major role in generating the initial permeability, allowing hydrocarbons to penetrate the lower Castile gypsum. The largest faults are associated with biogenic calcite and sulphur for a distance of 250 meters up from the bottom of the Castile gypsum. It is apparent that two dynamic geological processes are generating permeability within the gypsum beds: (1) the Cretaceous sands decending with difficulty into gypsum and (2) the faults creating permeability in the lower Castile but losing energy through soft bed deformation in the overlying gypsum. Both of these sulphur ore controls are mappable, but another large sulphur deposit of the magnitude of the Culberson Sulphur Mine has yet to be discovered. It appears that massive sulphur deposits are associated with the largest scale examples of each system, that is (1) high densities of deep sinkholes and separately

Jan 1, 1992

By Paul Richardson

This paper discusses the drilling techniques and equipment used by Loffland Brothers Company to drill the AEC's UC-3 large diameter shaft in Nevada. Included are pictures and illustrations of the drilling-mud circulating system, the surface and downhole drill-string and the special heavy-duty mast and hoisting equipment required to do the job. The purpose and method of lining the large diameter holes along with the technique and materials used to backfill the lining to hole annulus are discussed briefly. Areas requiring improvement in both equipment design and technology for large diameter shaft drilling are discussed briefly. Shafts as large as 140 inches in diameter to depths of 5,000 feet can be drilled with existing equipment and technology.

Jan 1, 1969

By John B. Jones

New concepts in shaft kiln processing are included in the design of two large diameter shaft kiln plants now under construction. One kiln will be used to produce cement clinker at the Boettcher plant of the Ideal Cement Company at Fort Collins, Colorado. The other kiln is for the semi-commercial oil shale plant for Petrobras, the Brazil National Oil Company at Sao Mateus do Sul, Parana, Brazil. Investigations on application of the new concepts are proceeding in a portable pilot kiln. The shaft kiln has long been recognized as a method of gas-solids contacting having the following principle advantages: l. High thermal efficiency 2. Ability to handle a variety of feed materials with a wide range of particle sizes 3. Minimum investment and operating cost

Jan 1, 1963

By John C. Wangaard

A method of raising by use of a cage has been used with considerable success at the Cary Mine, Hurley, Wisconsin, on the Gogebic Range. The Cary Mine is owned by the Odanah Iron Company, Pickands, Mather and Company, Managers. This method is known to have been used previously at Tennessee Copper and probably in other districts. The Cary Mine was engaged in deepening the main shaft from the 34th to the 37th level. To accomplish this, and to facilitate development, a ventilation shaft 930 feet north of the main shaft was sunk from the 34th to the 37th level and crosscuts were driven on the 35th, 36th and 37th levels to the main shaft location, These levels are at 200 foot verticalintervals. All of this work was done in granite and the majority of the workings were not timbered. The next step was to get a raise through from the 37th to the 36th level, and from the 36th to the 35th level, which would later be stripped to full shaft size. Several methods of raising were considered including double-compartment cribbed and two single raises interconnected at regular intervals, but the cage method was chosen as it appeared to be a safe and efficient operation. The method in general consists in the use of a drill hole between levels through which to pass a hoisting rope to raise and lower a light cage.

Jan 1, 1958

By D. Robert Weir, Roman M. G. S. Berezowsky

Pressure oxidation can virtually always render refractory auriferous sulphidic ores and concentrates amenable to cyanidation. Its effectiveness as a pretreatment of refractory gold feedstocks is reflected by the successful startup and operation, over the past four years, of four commercial plants. At least three more are scheduled to come on stream during the next three years. Over the past eight years, a variety of ores and concentrates have been subjected to integrated miniplant testing and process demonstration by Sherritt, and data derived from these studies have been used in the design and construction of several of the commercial facilities. Some factors affecting the selection of pressure oxidation in gold recovery processing are discussed.

Jan 1, 1989

By T. K. McMahon

Formally, a mathematical model could be defined as: A set of equations whose solution will approximate the response of a physical process or system to a set of stimuli which appear as parameters in the equations. The purpose of a mathematical model is to permit the rationalization of experience to proceed by simulation rather than by physical experimentation. In the application of digital computer control to an industrial process, the mathematical model of the process (subsequently called the process model) is needed to calculate the present process performance from the measured variables and to predict the response of the process to a control change. Functionally, the cardinal element in process model development is a concise set of control objectives. These, besides implicitly defining the boundaries of the system to be modeled, will determine the accuracy demanded of the model its nature: dynamic or steady-state, and so forth, The objectives should explicitly define what process efficiencies, production rates, qualities are to lie within the scope of the computer control project, thereby providing a basis for simplifying assumptions in the development of the model. This requirement, a limited set of control objectives, is so often disregarded in formulating industrial control problems that its repetition can scarcely be avoided.

Jan 1, 1965

By Sundar S. Saluja

Efficient and re1iable methods of fragmentation through blasting have been sought ever since the introduction of black powder in mining operations, but the pace of investigation became faster with the discovery of nitroglycerine. The development of modern measuring instruments and the need to blast more rock with the least damage has made the study of blasting mechanics and its application more important, particularly since the oil embargo. Investigations into the practical approach evolved by Daws (1909) and the work done to make it more useful is discussed. The work of several investigators is touched upon with particular reference to the development of computer programs to simulate and optimize blasting operations.

Jan 1, 1986

Surface contamination of minerals during fine grinding may occur due to coating of one material on the other. This can alter the surface chemical properties and adversely affect the separation of minerals by physico-chemical processes. In dolomite-silica system, selectivity was completely lost (compared to a synthetic mixture) after wet grinding of the minerals in spite of using a dispersant. Adsorption and surface characterization studies were conducted on silica particles separated after grinding with dolomite. SEM-EDAX analysis indicated the presence of dolomite on silica particles, which could cause the loss of selectivity.

Jan 1, 1993