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By Jerry C. Tien

This paper investigated the airflow pattern in the working face area during a cross-cut development. The study used a 10:l scale face model and a mock continuous miner. Results showed that keeping up the line curtain is essential in order to avoid recirculation and to control respirable dust and methane, in the face area.

Jan 1, 1989

By I. Toromanoff, F. Habashi

The transformation of a low-grade titanium slag into synthetic rutile or synthetic anatase can be enhanced by attrition grinding.

Jan 1, 1987

By D. V. Ramani, M. M. Kissel, M. T. Ityokumbul

Experiments were carried out to determine the efficacy of bubble column flocculation. An acid-base neutralization method was used to determine the mixing time in a 0.064- by 1.5-m bubble column equipped with a Mottporous sparger. The mixing times decreased as the tracer injection point approached the gas sparger. Preliminary flocculation experiments on two clay samples were carried out. The effects of frother addition and airflow rate are presented and discussed.

Jan 1, 2000

By Andy W. Stephens, William H. Langer

In Australia and America, encroachment by conflicting land uses, zoning restrictions, and the "not in my backyard" syndrome make it increasingly difficult to access high-quality aggregate resources located near the market areas. Attempts by government agencies in America to protect aggregate resources for future development have met with varying degrees of success. The State of Queensland, Australia, designates aggregate resource areas as Key Resource Areas, which protect the resource and the routes to transport the resource, provide a separation area from incompatible land uses, and indicate the likelihood that the area is free from conflicting social or environmental issues.

Jan 1, 2005

By R. Hogg, T. F. Dumm, L. G. Austin

The applicability of SEM/EDS techniques to particle-by-particle analysis of respirable coal dust is evaluated. It is demonstrated that the correction procedures needed to account for the failure of most EDS systems to detect light elements (especially carbon) become unreliable for particles in the respirable size range (< 10 µm). Other serious limitations arise from x-ray counting errors for coal particles with low but significant mineral content and particle counting errors for liberated mineral matter.

Jan 1, 1991

By Alfredo Dammert

The paper presents the results of a model built at the World Bank in order to analyze the aluminum industry. Bauxite demand for the year 2000 is estimated as a function of alumina refineries&apos; requirements and of non-metal uses for bauxite. Bauxite supply by countries or regions depends on economic factors such as investment costs, operating and transportation costs, as well as on tariffs and levies. Various scenarios are considered as a result of varying the assumptions of the model.

Jan 1, 1984

By R. J. Snoby, P. Grotjohann

In processing heavy-mineral sands, the low feed concen¬tration and respective high value of the desired minerals require high-capacity production and sharp classification/ separation techniques to reduce the specific production costs. This paper describes the new allfux® separator, which can economically accomplish these criteria. The separator is a two-stage process that combines rising current and fluidized-bed technology. This allows for the treatment of ex¬tremely high mass flows in a single unit. This paper reports on test work performed on coal, iron ore and heavy minerals.

Jan 1, 2000

By Dominic F. Howarth

Cuttability and borability assessment methods in rock and coal are reviewed. TBM, roadheader and coal cutting machine boring rates can be predicted from a knowledge of machine, intact rock property and rock mass parameters. Results that were obtained from a detailed analysis of two TBM borability prediction methods and comparison with data from twenty case histories, show that a simple, low-cost method that uses one machine parameter and one rock parameter compares very favourably with a sophisticated, high-cost method that also includes details of rock mass characteristics (discontinuity, type frequency and orientation).

Jan 1, 1987

By J. Muir

This report focuses on minimum ore block sizes that are economically feasible to mine with the vertical crater retreat (VCR) method. In 1985, Homestake Mining Co. began a program to bring several small block VCR stopes on line. This report examines these experimental stopes, including design parameters, ground control, drill patterns, secondary blasting, and mucking. Cost and scheduling comparisons are made with mechanized cut-and-fill and open cut- and-fill methods.

Jan 1, 1987

By M. J. Sapko

The US Bureau of Mines conducted, through joint funding with the Colorado Mining Association, large scale oil shale rubble fire tests to investigate flammability characteristics and different methods of extinguishment. Ignition of large rubble piles was easily accomplished. Foam blankets could he used to control surface flames. The results of these large scale tests confirmed that water was effective but not particularly efficient in extinguishing deep seated oil shale fires. It took up to 1.7 times as much water to extinguish afire as anticipated on the basis of a simple cooling model, assuming 100% utilization.

Jan 1, 1990

By R. Hogg

The factors which control the dewatering of fine coal by gravity/centrifugal drainage and by gas displacement (vacuum/hyperbaric filtration) are evaluated. A generalized model is presented and used to describe dewatering kinetics and to establish dewatering limits. Applications to the design of dewatering systems for fine coal dewatering are discussed.

Jan 1, 1995

By Z. B. Yin, R. W. Bartlett, P. R. Taylor

Tube furnace experiments have been performed to evaluate the lime roasting of pyrite in air. The sulfur volatilized was measured over time. Variables studied included: form of lime, sodium sulfate additions, temperature, air flow rate, lime to pyrite weight ratio and pyrite particle size. It was found that more than 98% of the sulfur can be retained at a reactor temperature of 650°C, with a slight excess of calcium hydroxide. The roast products are primarily hematite and calcium sulfate.

Jan 1, 1990

By Lynton S. Land

Representative collections of recent dolomites, and of samples concentrated by leaching-out of coexisting magnesian calcites, provide grounds for appraisal of the compositions and cation ordering in recent dolomitized sediments. Unit cell volumes for near-stoichiometric compositions exceed those of ordered dolomite and increase as the departures from regular cation order became more pronounced. Infrared absorption maxima of disordered examples occur at perceptibly lower frequencies. Stable isotope ratios indicate that best ordered examples formed in highly saline environments. Present observations are qualitatively reconciled with data from synthetic products described by other authors.

Jan 1, 1972

By Yong Kang, Renhuan Yu, Xinquan Liu, Liangying Chu, Qian Luo

In grinding-classification circuit, overgrinding, resulted from the fact that hydrophobic materials have higher density than hydrophilicmaterials, has been known as a knotty problem. By using of the air-sparged hydrocyclone (ASH) as classifier, in this pair, the overgrinding of hydrophobic materials has been successfully minimized. Compared with the conventional hydrocyclones, the ASH has less fine hydrophobic particles in the underflow and less large particles in the overflow, which shows that the recovery of fine hydrophobic particles in the overflow has been improved in the ASH.

Jan 1, 1995

By M. J. McPherson

The legislation that prohibits the recirculation of air in coal mines was formulated because of the fear that concentrations of airborne pollutants would rise to dangerous levels. This paper undertakes a simple analysis of the effects of a controlled recirculation system on the gas concentrations in headings. It is shown, through an algebraic formulation and a numerical example, that a properly planned system of controlled recirculation leads to a reduction in the maximum general body gas concentration that occurs in a heading.

Jan 1, 1988

By R. L. Wiegel

There are approximately 40 million tons per year of phosphate rock produced in the United States, half of it by flotation. The bulk of this is used to produce diammonium phosphate, an essential ingredient in the commercial fertilizer mixes used by the thriving U.S. agricultural community. This paper describes the mineral beneficiation practices of the phosphate industry, with special emphasis on flotation. There is also an attempt to include those items that might be considered emerging technologies for the industry as it faces the problems of a diminishing high-grade reserve and the necessity for implementing dolomite/francolite separations.

Jan 1, 1999

When longwall equipment is being specified, a nominal capacity is generally given on which to base the design of the various face and out-bye systems and components. This capacity generally comes from a nominal annual capacity requirement based on realistic utilization rates. From illustrative examples of simple system simulation, this paper sets out to show that a single nominal capacity is not sufficient to size the different systems. The manner in which the Longwall is operated and the overall system configuration and availability can have a significant impact on overall productivity.

Jan 1, 2008

By Fathi Habashi

THE MINERAL monazite (µ?v??e?? = to be alone) is a rare earth phosphate containing some thorium and small amounts of uranium. It is widely distributed in the earth&apos;s crust. It occurs in small proportions in granites. Table 7-1. Mineralogical analysis of Rosetta black sands, U.A.R. (Nakhla, 1958). [Black sands Concentrate Augite 10.8 - Calcite 1.1 - Felspar 0.1 - Garnet 1.8 - Hornblende 2.4 - Ilmenite 50.7 8.0 Magnetite 15.3 Monazite 1.1 84.3 Quarz 7.3 - Rutile 1.0 0.5 Titanite 0.2 - Zircon 7.3 7.1 Others 1.0 0.1 100.0 100.0]

Jan 1, 1970

By D. H. Y. Tang, S. S. Peng

Three-dimensional finite element modeling (3-D FEM) was performed to analyze the safety factors of stump pillars, 5.5 m x 5.5 m, under a cover of 63 m using the Modified Drucker-Prager Theory. The results showed that they were safe. This was substantiated by underground observations. But the safety factors predicted by three commonly used pillar design formulae showed otherwise. This paper discusses the modeling details and analyzes the difference between 3-D FEM method and traditional pillar design formulae.

Jan 1, 1987

By William J. Francart, Gary J. Wirth

Fire detection capability in conveyor belt entries of coal mines has advanced considerably since the passage of the Federal Coal Mine Health and Safety Act. The advances in instrument technology and computer based monitoring have provided better fire detection than ever introduced in the industry. This paper discusses recent belt conveyor fires and detections in mines utilizing CO Monitoring Systems. Data from investigative reports is presented on belt entry fires from 1991 to the present.

Jan 1, 1993