Search Documents

By Brian R. Zelenka

The Bureau of Mines (Bureau) reviewed all available information regarding geologic and depositional processes contributing to potential coastal and offshore platinum group metal (PGM) placer deposits around the Goodnews Bay Mining District. The Bureau found that favorable environments for PGM along with gold and chromite enrichment include: (1) buried paleofluvial channels; (2) recent paleofluvial channels with little marine sediment overburden, (3) beach deposits, particularly in the upper swash zone and near back beach environments; (4) paleostrand lines; (5) shoal lag deposits inside the mouths of Goodnews and Chagvan bays; and (6) bases of far offshore tidal ridges which may represent reworked glacial deposits. Limited geologic and compositional (assay) data prevent determination of deposit size and grade of PGM mineralization for each deposit class. Future geologic sampling requirements for demonstration of identifiable offshore and beach PGM-bearing placers are discussed. Beach and offshore sampling programs conducted by the Bureau in 1986 will contribute additional information providing verification of specific deposit classes.

Jan 1, 2011

By M. K. Quinn, N. P. Reddy, A. W. Khair

"An analysis of coal fragmentation due to the action of a continuous miner is presented. Underground coal cutting by a drum-type continuous miner was simulated in the laboratory using a specially designed unique automated rotary coal cutting simulator (ARCCS). The rotary coal cutter provided the versatility of varying the operating and in-situ parameters to provide information on the effects of generating 37 pm (0.0015 in) particles. In these tests, coal blocks with an approximate dimension of 50.8 x 35.6x 20.32 cm (20x 15x 8 in) were first subjected to confining pressures equivalent to in-situ conditions. The blocks were then cut by the rotary cutting head of the ARCCS, thus simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-situ and operating parameters a number of other parameters such as (1) penetration of bit into coal, (2) penetration resistance (thrust and cutting pressures), (3) rotating velocity of' cutting head, and (4) acoustic emission activity in the coal block were monitored. During the test, all the cut products were collected for size distribution analysis. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted using a sonic technique. At the end of each experiment the cutting paths of the bits in coal were photographed using a camera attached to an optical microscope.The results led to a better understanding of the mechanisms of the fragmentation process during coal cutting and the effect of operating parameters, in-situ conditions and coal type on the size distribution of the cut product:"

Jan 1, 1989

By P. D. Kovscek

The Bureau of Mines has tested a low-thrust water-jet-assisted rotary drill. This work was performed to evaluate the performance of a water-jet-assisted drill operated at thrust levels typical of a handheld manual-thrust operation. Prior work by the Bureau had indicated that using water-jet assist with high-thrust drilling applications would increase drilling rate. Small-diameter holes were drilled in five different types of rock. Thrust and water pressure were varied as the drill rate was monitored. The test results indicate that drilling rates increase with increasing water pressure and thrust. The water jet has more effect on reducing the specific energy when drilling in the harder rocks than in softer rocks. Variation in drill rate for a given rock sample is attributable primarily to the material heterogeneity within the sample. One rock type (Greenwich sandstone) could not be drilled efficiently with the water-jet-assisted drill.

Jan 1, 1988

By Raja V. Ramani, Robert L. Frantz

"In response to the U.S. Bureau of Mines (USBM) Request for Proposal (RFP) for "" the establishment of a Generic Mineral Technology Center (GTC) in Respirable Dust,"" the Mining and Mineral Resources Research Institutes (MRIs) at The Pennsylvania State University (PSU) and West Virginia University (WVU) in association with participating MRIs at Massachusetts Institute of Technology (MIT), and the University of Minnesota (UMN) have prepared the comprehensive research program described herein. Michigan Technological University (MTU) joined the Center as an affiliate after its inception. This program was developed with recognition of the stated objective of the Federal Mine Safety and Health laws which is to "". . . permit each miner the opportunity to work underground during the period of his entire adult working life without incurring any disability from pneumoconiosis or any other occupation-related disease . . . .""Exposure to respirable contaminants in mine atmospheres has long posed a serious hazard to miners. The control of these hazards, some of which can have sudden and catastrophic consequences and some others, slow and long enduring, has been a major concern for labor, management and the government. This concern has manifested itself in four mechanisms of control -- (1) regulatory control through minimum standard setting by the passage of mine health and safety laws, (2) engineering control through design and operation of mines according to the best recommended practices, (3) interaction of dust and lung control through periodic physical examinations, wearing personal protection devices, etc., and (4) legal and social control through workman's compensation laws for occupation related health deterioration."

Aug 31, 1989

By Errol D. Sehnke

This U.S. Bureau of Mines report provides detailed information on worldwide alumina production capacity by plant and country. The information was compiled from a variety of domestic and international sources and was based on information available to the Bureau through December 31, 1993. Capacity data represent announced installed and planned capacities and do not necessarily reflect a Bureau of Mines judgment of actual plant operating levels or timing of planned expansions, The year-end capacity is the ?nameplate" capacity or estimated production capacity, whichever is larger.

Jan 1, 1993

By Irving Hartmann

Rock-dusting of coal mines is a most important safety measure for preventing or limiting the propagation of explosions. The Bureau of Mines has recommended for many years that rock dust be distributed on the top, ribs, and floor of mine entries and other workings of all bituminous coal and lignite mines in sufficient quantities to maintain the incombustible content of the dust above the minimum requirements. Rock-dust barriers constitute a secondary safeguard used occasionally to complement generalized rock dusting at entrances to panels and side entries or at other locations. In general, rock dust can be applied effectively with modern rock-dusting machines. However, in thin coal beds, in certain back entries, and in some other areas, rock-dusting machines cannot be used conveniently. Furthermore, many small mines find the purchase of machines costly. In such cases, rock dust is not used at all, or else it is distributed by hand, a relatively slow and costly procedure. In recent years some coal mines have started applying rock dust with the aid of permissible explosives. This may be done in various ways. One method consists in placing a stick of explosive on the floor of a room or entry midway between the ribs and covering the stick with two bags of rock dust that are slit on top and set crosswise one above the other. The explosive is then fired, causing the rock dust to be distributed on the nearby roof, rib, and floor surfaces. The procedure is repeated at desired intervals until the entire area is rock dusted. The method is claimed to be rapid, safe, and inexpensive.

Jan 1, 1950

By Wesley A. Grosh

The Toncrae-Howard copper deposits in Floyd County, Va., were first mined about 1800. The property has been operated or under development at various times since then for iron, copper or sulfur, although the total production has been small. The deposit consists of a vein or zone of sulfide mineralization in schist composed mainly of pyrrhotite with minor copper values in the primary zone and some rich areas of copper mineralization in the altered zone. The Bureau of Mines, in an attempt to develop minable copper ore during the war, opened part of the mine for examination and sampling, deepened the shaft and other underground work, and drilled 29 holes totaling 2,187 feet.

Jan 1, 1948

By Doris M. Hyde

The economy of Belize continued to be relatively unaffected by activity in the minerals sector. Mining production consisted of limestone, marl, and sand and gravel. All production was used for domestic construction projects. By the end of 1979 the major oil companies had, temporarily at least, ceased active exploration efforts. Esso Ventures, Inc., after drilling three dry holes in southern Belize, planned to reappraise its activities. The Reef Exploration, Ltd., concession was acquired by Anschutz Oil Co. (81.25%). with minority interests held by Anglo Oil Co. and Carolina Oil Co. The Anschutz group drilled offshore in the Gulf of Honduras and in Belize Harbor. Echo Exploration has a con-cession along the Mexican border and Spar-tan Petroleum Corp. obtained seven exploration licenses covering 768,000 acres in northern Belize. Spartan's concessions included about 130,000 acres offshore, with the remainder along the southeastern rim of the Yucatan Peninsula. Placid Oil Co. took an interest in the Spartan acreage and became operator. Seismic exploration was underway in 1979. A Mexican company, Pan American Oil and Gas, S.A., was awarded two exploration concessions, one in southern Belize and one near the Mexican border.

Jan 1, 1981

By G. V. Sullivan

This report summarizes the results of a preliminary study concerning manganese extraction from low-grade dolomitic materials from the Philipsburg district in Montana by the Dean-Leute ammonium carbamate process. Studies were made to determine the relationship between the variables involved in treating these materials by a roast-leach process and the amount of manganese extracted. The variables studied were the roast temperature, the roast particle size, the molar ratio of NH3 to CO2 in the leach solution, the liquid-solid ratio in leaching, the leach time, and the size of the particles being leached. The roast-leach studies were statistically designed, and the experimental results were evaluated by an analysis of variance.

Jan 1, 1962

By George W. Healy

The direct retorting of zinc sulfide concentrates in the presence of lime and carbon was examined on a laboratory scale with ten-gram charges of loose mix or fifteen-gram ones of pellets. A slow stream of nitrogen swept through the furnace tube over the boat of reactants, carrying with it the zinc vapor, which condensed on a rolled-up steel sheet near the exit, permitting weight of zinc produced to be obtained after completion of a run. Variables explored were percent of theoretical reagents, temperature, and time. During the runs gas samples were analysed periodically, and the content of CO2, CO and nitrogen were obtained. The quantities of the carbon gases could be calculated because the nitogen flow rate was measured. The gases were also examined for sulfur species, but neither COS nor SO2 could be detected at maximum sensitivity. Zinc recovery increased with excess carbon and lime and with temperature. It ranged from 77% at a ten percent deficiency to 90% at a ten percent excess at 1100°C. Going to 1200°C and theoretical reagents gave 93% recovery. Increasing time from 200 minutes to 300 minutes increased zinc yield by up to 10%. Results from sphalerite and a commercial concentrate from AMAX gave generally similar results. The reaction rate of zinc sulfide as sphalerite and of calcined sphalerite indicated that the latter reacted almost twice as fast, and recovery of zinc was five percent higher. Though the retorting step using sulfide, lime, and carbon proved to be non-polluting, it was feared that on storage the calcium sulfide in the residues would decompose, giving off noxious gases. Consequently the stabilization of the residues by oxidation was essayed. Because of the presence of unreacted zinc sulfide, the first product of oxidation was S02. Reaction of CaS to CaSO4 was incomplete, going from 20% at 800°C to 90% at 1200°C. Thus the non-polluting nature of the process as a whole is in doubt, and its economics are likely to be unfavorable compared to the traditional way of calcining the concentrates, followed by retorting of the oxide with carbon.

Jan 1, 1982

By F. N. Kissell, R. J. Bielicki, J. H. Perkins

A sorption apparatus for measuring the equilibrium sorption isotherm and the rate of diffusion of methane from fine-sized coal was designed and constructed. Preliminary work that used Pittsburgh and Pocahontas No. 3 coal shows that the diffusion coefficient varies with pressure and that the fracture spacing in these two coals is substantially different.

Jan 1, 1972

By S. G. McAnally

This is one of a series of papers describing mining and crushing methods and costs at cement plant quarries throughout the United States and deals directly with the methods employed and costs obtained at the Reliance quarry of the Giant Portland Cement Co. at Egypt, Pa., although it is more or less descriptive of the methods used throughout the Lehigh Valley cement district. Systems of transportation vary according to local conditions, such as proximity to the mill, depth of quarry floor with relation to the mill level, etc. Methods of prospecting differ mainly in the type f drills used. Systems of storage, crushing, and grinding vary chiefly in the types of units. ACKNOWLEDGMENTS Most of the information regarding the early history of the Lehigh cement district was obtained from the History f the Portland Cement Industry of the United States, by Robert W. Lesley, the first president of the Portland Cement Association. The writer is indebted also to Charles Clader, Giant Portland Cement Co. quarry superintendent, for valuable information regarding present and past methods and equipment.

Jan 1, 1931

By McElroy. G. E.

"INTRODUCTION The ventilation of development faces in mines for diluting gas or dust concentrations and, in hot mines for providing air-motion cooling effect, by fan pipe units discharging high-velocity streams of air close to the face, is an important phase of mine ventilation. The effectiveness of such units depends largely on the air-flow distribution between the pipe discharge and the face, a subject on which little definite information is available. A study of the air flow from grills into rooms 3/ has provided some basic data, but under conditions no different from mine fan-pipe installations in development ends that the data are of doubtful application to mine installations, owing to differences in air-flow conditions.The purpose of this report is to present and discuss the results of an initial series of tests of a general investigation designed to yield definite laws and design data for the discharge of fan-pipe lines in mines. This series was planned to yield preliminary data on the effects of velocity of discharge, size and shape of pipe, and adjacent walls on the air-flow distribution. Tents were made on 10-inch pine with seven different end conditions and one change of wall condition. Changes in size and shape of discharge wore made by short transformation pieces directly at the discharge end, with the result that effects due to contraction and expansion of the flow, which proved to be of much greater importance than was expected, totally obscured any normal effects due to size and shape. The results of this series of tests, therefore, relate to 10-inch pipe with various discharge designs and are so reported."

Aug 1, 1940

By Robert W. Smith

Computation of the thermodynamic properties of the reaction products in the deflagration of explosive gas mixtures has been a most valuable guide regarding the possible kinetic mechanisms of homogeneous combustion processes. Knowledge of the physically possible end states is indispensable for understanding observed deviations from equilibrium in heterogeneous combustion. However such information on dust flames is entirely lacking. To complement a Federal Bureau of Mines study of stationary graphite dust flames burning in pure oxygen,6/ this report gives examples, at atmospheric pressure and room temperature, of composition profiles in an idealized oxygen-dust flame, with both mass and enthalpy being preserved. Similar profiles can be obtained from the data of the paper for elevated temperature and pressure.

Jan 1, 1960

By Bruce D. Hanson

The Bureau of Mines conducted a series of ignition tests with two types of conical bits (plumb bob and pencil) used on continuous mining machines, to determine their ignition potential at various bit speeds, cut depths, and wear conditions. The tests were conducted using single bits mounted on a 34-in-diam drum in a Bureau ignition test facility. The bits impacted blocks of Berea sandstone in a 6.5 pet methane atmosphere at various bit speeds and cut depths. In a new condition, the plumb bob bits were considerably more incendive than the pencil bits, causing ignitions in 32 of 35 tests at 60 rpm, compared with ignitiolls in 2 of 22 tests for the pencil bits. The results from new bit testing also show that reduction of bit tip velocity to 180 fpm does not eliminate ignition potential. When subjected to progressive wear, bits of both types were more incendive when they were locked in place, unable to rotate, than when they were free to rotate.

Jan 1, 1983

By Henry G. Dorsett

This report is a description of equipment and test procedures used by the Federal Bureau of Mines in laboratory studies on the explosibility of dusts. The principal tests concern ignition temperature, minimum explosive concentra¬tion, minimum electrical energy for ignition, limiting oxygen concentration, pressure, and rates of pressure rise. As new materials often present unique problems, variations in the general procedure and special tests performed are indicated, The general procedures for handling a dust sample from its receipt at the laboratory to the preparation of the report are described. The repro¬ducibility of the respective tests are shown. A brief history of laboratory studies on dust explosions by the Bureau of Mines and a description of current equipment and test procedures used are presented in this report. Its purpose is to facilitate interpretation of data previously published and those proposed to be published on the numerous mineral, agricultural and industrial dusts that have been studied. Through understanding and interpretation of the laboratory data obtained for the parameters of explosibility, preventive measures can be adopted for alleviat¬ing the hazard of dust explosions arising in manufacturing and processing industries.

Jan 1, 1960

By R. E. Meaker

Electrical conductivities and densities of molten fluoride systems were measured as functions of the melt temperature and composition. For any given mixture, the two properties change linearly with temperature. Three alkali metal fluorides were selected as solvents for melts of the type LiF-, NaF-, and KF-MFx, where M is a metal selected from the alkali metal or alkaline earth groups, or from the lanthanide or actinide series of elements, and x = 1-4. Heats of activation for conductance were calculated from the experimental data and varied from 2.3 to 9.2 kcal/mole at 1,000° C. Some relation between position in the phase diagram and the conductivity changes was suggested.

Jan 1, 1971

By R. J. Bielicki

A sorption apparatus for measuring the equilibrium sorption isotherm and the rate of diffusion of methane from fine-sized coal was designed and constructed. Preliminary work that used Pittsburgh and Pocahontas No. 3 coal shows that the diffusion coefficient varies with pressure and that the fracture spacing in these two coals is substantially different.

Jan 1, 1972

By H. E. Dresch

This report summarizes the work accomplished under Bureau of Mines contract H0188068. The contract required design and construction of a high voltage (7.5 KV) explosion proof cable connector for use on underground coal mine drag cables. A connector was constructed with elastomeric phase insulators that provide insulation shielding throughout the connector length. Connector housing was made of flame resist-ant cast poly urethane with no exposed metal components. Electrical and mechanical testing of the completed coupler resulted in satisfactorily meeting most of the design testing requirements.

Jan 1, 1981

By John G. Kovac

A computer simulation has been developed to estimate the chances of a miner making a successful escape while wearing a SCSR. The model takes into account: (1) training in the use of SCSRs, (2) apparatus integrity, and (3) the oxygen cost of a mine escape. This Bureau of Mines report examines survival odds for a prototypical escape, and illustrates how these odds change when SCSR training is improved.

Jan 1, 2009