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By Hans von Michaelis

Gold metallurgy has advanced remarkably over the last decade. Even more significant progress will be made over the next five years, particularly in the application of advanced comminution techniques and control, preconcentration (flotation, ore sorting and coal gold agglomeration), enhancement of cyanide leaching technology, non- cyanide leaching, treatment of refractory ores and concentrates, and improved recovery systems. Carbon adsorption processes have become standard practice for ores with relatively high gold/silver ratios, but ion exchange potentially offers distinct advantages and has recently been demonstrated to perform better in at least one application. Even in the established zinc precipitation and CIP processes several important practical improvements are emerging as experience is gained at the ever increasing number of operating plants. Improved process control and reduction of reagent consumption costs are two important goals of industry at this time.

Jan 1, 1989

By S. Shankar

The phenomenon of re-entrainment is seen in many environments, such as sand dune formation, soil erosion, fugitive dust emission, spread of radio-nuclides from accidents involving nuclear weapons, etc. A thorough review of existing literature reveals that work on re-entrainment of dust in mine atmospheres is scant. The present study was undertaken as a part of on-going research in the Respirable Dust Center on the prediction of ambient dust concentrations in mine atmospheres (Ramani, 1983) to identify the contribution of dust re-entrainment to the spatial and temporal concentration in mine airways and included wind tunnel and in-mine studies. A set of seven experiments was performed in the Lake Lynn Laboratory Mine of the U.S. Bureau of Mines under controlled conditions. Two types of source coal dust, anthracite and bituminous, were subjected to airflow with a range of air velocities and walking by two different walkers. Six sets of instruments were used along the test section for sampling the airborne particles. The average air velocity just above the coal dust bed varied between 2.1 to 3.2 m/s. Due to re-entrainment as a result of the airflow conditions, the average respirable dust concentration in the center of the mine airway increased to 0.09 mg/m3 (standard deviation = 0.03 mg/m3) from an initial value of 0.02 mg/m3. The concentration of all (i.e., total) airborne dust increased to 0.17 mg/m' (standard deviation = 0.10 mg/m') from an initial value of 0.02 mg/m'. The action of personnel walking, however, caused higher amounts of re-entrainment. Average concentration of respirable and total dust at the center of the mine airway increased to values of 0.28 mg/m' (standard deviation = 0.12 mg/m3) and 1.53 mg/m3 (standard deviation = 1.0 mg/m3), from initial values of 0.03 mg/m3 and 0.05 mg/m3, respectively. It was observed that the dust concentrations were much higher near the floor, immediately at the end of the coal dust bed. Depending on the level of activity and the amount of dust deposited in mine airways, re-entrainment may become an important source of airborne dust away from the point of actual mining.

Jan 1, 1994

By Pierre Mousset-Jones, Felipe Calizaya, Malcolm J. McPherson

The objective of this study is to provide potential users of booster fans in coal mines with the necessary information on monitoring and control of fans and environmental factors. The guide-lines listed in this paper were formulated based on the current practice of mine monitoring, the U.S. Code of Federal Regulations on environmental monitoring, and the United Kingdom's National Coal Board recommendations on the use of booster fans. The principles involved in the design of booster fans as well as the provisions needed to guarantee a safe operation of these units, are illustrated by means of an example problem. The example includes a summary of costs for two ventilation systems: a conventional surface fan system and a fully automated booster fan alternative. A comparison of these costs showed that significant gains may be attained by selecting a combined surface-booster fan strategy over a conventional surface fan alternative.

Jan 1, 1989

By Lawrence R. Molsather

Certain hydrologic parameters are affected by development of a mine. These include the area, yield, and storage in a watershed. Alteration of these parameters results in variations in lake levels and stream flow rates and in changes in ground water elevations and gradients. These factors have become increasingly important in light of present environmental design standards and government regulations. Mitigation of adverse hydrologic impacts can be costly and can create operating constraints which complicate the mining process.

Jan 1, 1980

By C. T. Holland

Coal mining has been an important industry in the Appalachian area for many years. This is particularly true in the northern part of the area, namely, in Pennsylvania, West Virginia, and Ohio. Also, in the south a great deal of mining activity has been carried on in Alabama, Kentucky, and southwest Virginia. Some of the by-products of this activity has been the production of mineralized water from the mines in copious quantitites. The southern Appalachians have been somewhat more fortunate in that the water there has had a considerable amount of alkalinity in it, which has to a large extent eliminated some of the more undesirable aspects of mine drainage. Northern Appalachia, including central and western Pennsylvania, the Monongahela basin in West Virginia, and the Appalachian area in eastern Ohio have not been so fortunate in that coals in those areas and the top and bottom rock have, in many cases, shown considerable quantities of pyrite, and the water does not carry the carbonates found farther south.

Jan 1, 1969

By Gregg J. Hodges

The Stillwater Mining Co. is a partnership of The Pittsburg & Midway Coal Mining Co. and Manville Corp. The Stillwater Mine, located near Nye, MT, is the Western Hemisphere’s only primary platinum-palladium deposit. The mine began production of flotation concentrates in March 1987. In the fall of 1987, an integrated pilot plant testing campaign of electric furnace smelting and oxygen-blown converting confirmed the feasibility of further upgrading to semi-refined matte, or “white metal.” In the summer of 1990, the production smelter was brought on line. The record of the discovery and development of the Stillwater deposit, mine and concentrator has been summarized in several articles (White, 1987; Kennedy, 1987; and Hodges and Clifford, 1988). Similarly, the pilot campaign to test the feasibility of treating the flotation concentrates in an integrated smelting plant has been described (Hodges and Clifford, 1988; Matousek, et al., 1989; and Matousek and Whellock, 1990).

Jan 1, 1991

New South Wales (NSW) and Queensland dominate Australian black coal production and exports. NSW produced 86 Mt (95 million st) of saleable coal in 1994, a doubling of output since 1980. Asian demand for thermal and coking coal has driven this growth. This high Asian demand is expected to continue and NSW will seek to secure its share. History The history of the New South Wales (NSW) coal industry can be traced to 1797 when coal was first taken from Newcastle to Sydney (Ellis, 1969). At that time, NSW was a British colony, independent from the other colonies, such as Victoria and Queensland. Australia, as a federation of colonies, did not exist until 1901. The Newcastle coal industry grew through the 1800s in line with the growth of the colonies. Several events spurred demand for Newcastle coal. These included: ? The NSW and Victorian gold rushes of the 1850s and associated population growth. ? The development of steamship traffic at the expense of sail. ? The development of railways and town gas supplies. By 1900, Australia was producing 6.4 Mt (7 million st) of coal, most of it from NSW. By then, NSW had established strong export markets in Indonesia, China, Japan and New Zealand. The history of energy consumption is marked by continual competition, changing intensity of use and substitution. From 1900 to 1940, the Queensland, Victorian and Indonesian coal industries developed at the expense of NSW exports. Similarly, New Zealand developed its hydroelectric industry and thus declined as the largest customer for NSW coal. Oil replaced steam in the shipping and railway markets and electricity replaced gas for lighting. Industrial efficiencies also affected coal. Between 1928 and 1938, coal consumed in generating power fell from by 17% on a kilowatt hour basis and, during the same period, the amount of gas produced per ton of coal rose by 18% (Shaw and Bruno). Faced with these pressures, production and exports stagnated. By 1941, Australian black coal production was 14.2 Mt (15.6 million st). NSW's production was 11.7 Mt (12 million st), up only 19% from 1912. Exports had virtually ceased (Fig. 1). In such circumstances, the industry had lost focus. Unions resisted the need for mechanization, for security of employment reasons, and owners were loath to invest. This reluctance to mechanize and the associated in-

Jan 1, 1997

By Chris Joyce, Peter Ryan, Graeme Mcllveen

This paper briefly summarizes regulatory procedures and government agency roles and jurisdictions in each Australian State and Territory. The role of the Commonwealth of Australia and selected current trends in environmental regulation are also discussed. While the Commonwealth has played an active role in regulating specific commodities or mines through its powers over export licences, international heritage agreements and the Territories, such cases have largely been a result of response to specific public issues. This may change; the Commonwealth has established the Resources Assessment Commission and is canvassing the establishment of an Environmental Protection Act, aimed at the standardization of environmental standards through the creation of an Environmental Protection Authority. While the States, the Northern Territory and the Commonwealth lwve nominally different resource planning, environmental project approval and operational regulatory authoritit:s, the fundamental principles hinge on mining lease, planning and pollution control approvals.

Jan 1, 1991

By V. Arad, S. Arad

Besides the conservation and closing activities, an important issue to achieve is the environmental rehabilitation of the mining perimeters, also assuring the continuity and sustainable development of the mining activity in the Jiu Valley. Modifying and depleting the soils by mining works and dumps of mineral waste as a result of coal mining and tailing is one of the important aspects. The paper’s aim is to analyze which are minerals and resources policies of our government and to adopt measures for sustainable development in the coal mining in this region. The measures to reduce the instability risk for the mining works and waste dumps, which could affect the underground mining constructions or the related surface areas, were consider. It is most important to establish the priorities in order to obtain a high efficiency by combining the measures according to the environmental analysis and risk assessment.

Jan 1, 2005

By Phillip R. Moyle

Voluminous deposits of commercial-grade phosphate occur in sedimentary strata in a 350,000 km2 (135,000 mi2) area of the middle Rocky Mountains of North America known as the Western Phosphate Field. The Permian marine strata that host the phosphate were deposited on the western margin of the North American craton and subsequently deformed, first by folding and thrust faulting of the Laramide orogeny, and then by Cenozoic Basin and Range block faulting. Carbonate fluorapatite is the primary phosphorus-bearing mineral. Organic matter is abundant in some strata, and both biogenic and non-biogenic pyrite are also present. Certain strata are enriched in several trace elements, especially in arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), molybdenum (Mo), selenium (Se), vanadium (V), uranium (U), and zinc (Zn). Phosphate has been mined from the Western Phosphate Field for nearly 100 years. Phosphate mining and processing constitutes the largest mineral industry of Idaho, producing more than $600 million in processed mineral value in 1997. Resource management agencies, phosphate producers, and others are concerned about the release of Se from phosphate mine wastes, especially at Maybe Canyon, and the potential effects that Se and other trace elements may have on the environment and on human health. U.S. Geological Survey (USGS) Mineral Resources Team scientists initiated a multidisciplinary study of the Permian Phosphoria Formation and related rocks in the south- eastern Idaho sector of the Western Phosphate Field in response to a request by the U.S. Bureau of Land Management (BLM). Studies to date reveal that Se is present in several phases, including native Se, and in an as yet unidentified form, possibly an organo-Se compound. Selenium is also present in pyrite and sphalerite. Selenium concentrations range from 1.2 to greater than 1,000 parts per million (ppm) in samples collected from exposures of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation (Meade Peake) at Enoch Valley. The results suggest that Se concentrations vary spatially across strata and with depth, perhaps comparable to spatial variations of phosphate and organic carbon concentrations throughout the Western Phosphate Field demonstrated in previous studies. Some Se-enriched strata may be of adequate dimension to allow selective extraction during mining. Such units could be handled separately from the main ore process or waste streams and isolated in order to reduce the potential for release of Se to the environment

Jan 1, 2001

By J. Lizak

Calcium carbonate is one of the highest volume industrial mineral products in North America. It is used in filler and extender applications, roofing products, floor tile, glass manufacture, etc. Calcium carbonate has over a dozen major filler and extender applications plus a host of minor uses. North American consumption of calcium carbonate fillers and extenders in 1991 is estimated at over 5,000,000 tons valued in excess of $400,000,000. There were five major suppliers of calcium carbonate fillers in the Middle Atlantic region in 1988 :?Bestone, Genstar, National Gypsum, Thomasville Stone and Lime, and White Pigment. With the exception of Genstar's Maryland operation, all of these operations are within a few miles of York, Pennsylvania. The Millington Group (TMG) purchased the assets of Bestone Corporation in February of 1989. TMG then seized the opportunity to strengthen its business position by acquiring National Gypsum's and White Pigment's Pennsylvania filler businesses in December, 1989 and July, 1990, respectively. By July of 1990 TMG's filler business acquisitions included six quarries and one underground mine, totaling over 1,200 acres and three processing facilities. The assets were restructured into two new companies - Delta Carbonate, Inc. and Penroc, Inc. (hereafter collectively referred to as Delta). Delta identified the assets of the three predecessor companies as undervalued from the outset. The initial phase of Delta's turnaround strategy was to reassess the combined mineral. mining, processing, transportation and marketing assets. The second phase was to effectively integrate these resources in order to exploit their inherent synergy.

Jan 1, 1992

By H. J. Handewith, W. D. Coski

This paper describes the development and testing of the RAMEX excavation system. Incorporating a synergy of low velocity, high energy impact and kerf cutting, this machine offers a competitive alternative to drilling and blasting in hard rock. It is a boom mining machine that incorporates the features of a lightweight roadheader and it can mine nearly any shape opening in hard rock. The RAMEX Tunneler has been developed to satisfy industry demands for a non-explosive, flexible, continuous and rapid underground rock excavation system. It will produce minimum ground vibration in the urban environment and allow the flexibility necessary for thin seam mining conditions. It will also reduce initial ground support costs and has a minimum impact on rock integrity. Developed by RAMEX Systems with cooperative research provided by the U.S. Bureau of Mines, this system, could produce the next step in the continuing evolution of mechanical mining systems.

Jan 1, 1989

By K. R. Griffin, K. D. Luxbacher, E. C. Jong

The schlieren technique describes an optical analysis method designed to enhance light distortions caused by air movement. The ability to visualize air flow has significant implications for analyzing underground mine ventilation systems, including the enhancement of surveys and models. Currently, traditional schlieren methods are impractical underground. Background-oriented schlieren (BOS) provides a solution to this problem. BOS requires two primary components, a professional quality digital camera and a schlieren background. A schlieren background is composed of a varying contrast repetitive pattern, such as black and white stripes. This background allows the camera’s sensor to capture minor light diffractions, such as those caused by air flow. Although BOS shows great potential for ventilation analysis, sensitivity is an issue. This paper seeks to validate the BOS technique for imaging flow through a regulator by comparing BOS images with traditional schlieren images. This paper also outlines initial experimental efforts used for the validation.

Jan 1, 2011

The use of controlled recirculation can be dated back to the early 1930s. Although this method has been applied in many mines since then, a generalized comprehensive network analysis is still lacking. This paper presents a unique approach in which the ventilation network with a controlled district recirculation is divided into two subsystems: a main subsystem and a recirculation subsystem. The subsystems are analyzed individually and the results and their relationships are then integrated into discussions of the total ventilation system. The analysis of the recirculation subsystem is facilitated by introducing a non-dimensional parameter A, which represents the ratio of the air quantity for the working face to that for the subsystem. As a result, fan and regulator pressures and air power for various recirculation arrangements can be effectively expressed as a function of A and the subsystem air quantity. Numerical examples are included.

Jan 1, 1995

By C. O. Brawner, A. Bellamy, D. S. Cavers

Pit slope designs at Nickel Plate Mine have used relatively steep interim and final wall slopes of 60 degrees overall. The rock is unusually strong and tough with most discontinuity sets being steeply dipping. An integrated program of monitoring and drainage has been used. Stopes of large extent which are generally unsupported occur on the property. For the most part, no deterioration of the stability of the stopes has occurred over the last 30 or more years. Mining methods through these areas have used a combination of fill s placed via VCR drop raises and crater blasting of the backs. One of the major challenges in mining through the stope areas is to maintain slope stability conditions and to reduce dilution of the higher value ore zones occurring immediately around the stope areas. The paper discusses geology, slope stability and mining methods at Nickel Plate Mine.

Jan 1, 1988

By Donald G. Foot

The Bureau of Mines, U.S. Department of the Interior, devised a direct flotation method for treating low-grade carnallice (KC1.MgC12. 6H20) and sylvinite (a mixture of KC1 and NaC1) ores characterized by a high content of water-insoluble impurities. The procedure consists of (1) flocculation-depression of the insoluble slimes, (2) decomposition leach (carnallite only), (3) potash rougher, cleaner and recleaner flotation, and (4) final product leaching. The technique eliminates the necessity of removing the water-insoluble slimes by mechanical or flotation desliming. Laboratory results demonstrated that the direct flotation procedure, when compared with conventional techniques, yielded equivalent or improved flotation results with equal or less reagent consumptions. The direct flotation method recovered 81.6% of the solid-phase KC1 from carnallite ore and 79.7% of the KC1 from sylvinite ore in final products containing 60.5% and 60.9% K20, respectively. A flowsheet incorporating the described flotation procedure is presented.

Jan 1, 1981

By Pramod C. Thakur

Sixty countries around the world mine about 5000 million tonnes of coal annually and simultaneously produce nearly 25 million tonnes (36.8 Gm3) [One tonne of methane at a temperature of 15°C and a pressure of 760 mm of mercury has a volume of 1471 cubic meters.] of methane. Many of these coal mines are very gassy and require methane drainage prior to mining as well as during mining. In spite of significant differences in the geology and reservoir properties of the coal seams, several methane drainage techniques have found universal application. The paper describes various techniques currently in use and their efficiency in recovering methane from mines. It appears that the application of state-of-the-art techniques, developed mostly in the U.S.A., can considerably increase the efficiency of methane recovery and improve the safety of mines throughout the world.

Jan 1, 1997

By D. D. Harbuck, G. K. Green

The Bokan Mountain area on Prince of Wales Island, AK, contains vast quantities of heavy rare earth minerals. To lessen the US dependence on foreign sources, the US Bureau of Mines (USBM) investigated yttrium recovery from this ore. By sulfating the ore at 250 ° C for 1 hr at an H2S04:ore ratio of 1:1 and then water leaching the sulfated material for 1 hr at 20% solids and 25ºC, over 74% of the yttrium, cerium, and lanthanum were solubilized. Solvent extraction (SX), using a synergistic combination of OPAP and DEHPA, selectively loaded 100% of the yttrium. Yttrium was stripped directly as a solid using a 2M, 35 ° C NaOH liquor. When the OPAP/DEHPA mixture was tested in a continuous SX circuit, yttrium loading and stripping were 100% and 96%, respectively. The organic showed excellent recyclability properties with minimal solvent loss.

Jan 1, 1996

By G. T. Adel

During the past decade, researchers at Virginia Polytechnic Institute and State University have worked to develop a novel flotation process for treating very fine particles. This process, which is now commonly known as [microbubble column flotation] (MCF), has been shown to be very effective in a number of applications related to fine coal processing. These applications include the retrofit of existing preparation plant circuits and the recovery of additional coal fines from refuse streams. In addition, work conducted under the sponsorship of the United States Department of Energy indicates that the MCF process is capable of producing superclean and ultraclean coals from many eastern U.S. coals. This paper describes some of the basic problems associated with fine particle flotation and the design and operational features of the MCF process used to minimize these problems. Also presented are the results of ongoing pilot- and field-testing programs.

Jan 1, 1989

By S. K. Kawatra, S. J. Ripke

During 1998, 62 million tons of iron ore pellets valued at $1.7 billion were shipped from U.S. mines. These pellets are the primary source for domestic iron and steel production. During pelletization, binders are required to improve the green strength of the pellets. Each year, bentonite binder costs a typical plant from $3 million to $5 million. Reducing the bentonite dosage has the advantages of significant cost savings while producing higher quality, lower silica pellets. The authors have recently identified a new and important bentonite binding mechanism, the fiber theory. During this study, procedures were developed that took advantage of the ability of bentonite to form fibers, and resulted in a dramatic decrease in the necessary bentonite dosage. Acceptable quality pellets were produced with the bentonite dosages reduced in half from 14 lb/lt (0.66%) to 7 lb/lt (0.33%).

Jan 1, 2001