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The strike of the Canadian asbestos miners entered its seventh month with increasing signs of early termination. Both unions are in the midst of heavy negotiations with management, and an optimistic industry source predicted that work would resume by October 1. Recession recovery in some segments of the asbestos manufacturing industry is being impeded by lack of fibers, CADMIUM - On September 9, St. Joe Minerals Corp. reduced the price of cadmium metal to $2.75 per pound. The producer price bad been uniformly quoted at $3.00 per pound since June 26, 1975. Subsequently, Amax, Inc. and National Zinc Co. reduced their prices to $2.50 per pound. By mid-September all five U.S. cadmium producers were marketing the metal at $2.50 per pound.

Jan 1, 1975

By Jürgen F. Brune, Liming Yuan, Alex C. Smith

To provide insights and assistances for the optimization of ventilation systems for U. S. under-ground coal mines facing both methane control and spontaneous combustion issues, a computational fluid dynamics (CFD) study is being conducted to investigate the effect of the ventilation scheme on the prevention of spontaneous combustion in longwall gob areas. This report focuses on the flow patterns within the gob under three different ventilation systems; one-entry and two-entry bleederless systems as well as a three-entry bleeder system. The gas flow in the caved gob area is simulated as a laminar flow through porous media while the gas flow in ventilation airways is simulated as a fully developed turbulent flow. The air flow patterns are visualized using flow path lines. Air velocity contours and vector data are also obtained. The possible location of critical velocity zones where the gob is most liable to spontaneous heating is discussed.

By W. R. Hardwick

Nuclear explosive fracturing has been suggested as a method to make hard rock amenable to extraction by a modified block-caving method. To evaluate this possibility, conventional and nuclear blasting practices are discussed, underground mining methods for large deposits and their costs are described, and the cost of fracturing ore with a nuclear explosive and subsequent mining by a modified caving system is estimated and compared with both open-stope and block-caving mining costs. While the direct cost of fracturing the ore in hard rock with a nuclear explosive is less than with conventional explosives, additional costs imposed by the use of nuclear explosives may make their use unattractive for deep mining.

Jan 1, 1970

By E. R. Spencer, E. R. Bauer

Previous studies and research efforts have shown that noise-induced hearing loss (NIHL) is a problem in the U.S. mining industry. In response, researchers at the National Institute for Occupational Safety and Health (NIOSH) have been conducting a cross-sectional survey of equip­ment noise and worker noise exposures in the mining industry to estimate the potential for NIHL within the mining community. One commodity recently surveyed was the extraction of sand and gravel from surface pits and by dredging. To address the potential for NIHL in the sand and gravel industry, sound levels on and around the dredges and processing equipment were recorded to iden­tify areas of high noise levels. Full-shift worker dosimetry, in conjunction with task observations, was documented to determine the relationship between exposure and source. This paper presents research examining noise on dredges used in several surface mine sand and gravel operations and in the processing facilities. Results indicate that there are areas on the dredges (crane, suction pumps and diesel engines) where sound levels greater than 90 dB(A) are pres­ent. In addition, crushers and screens used in the processing of the sand and gravel also generate sound levels greater than 90 dB(A). Although no surveyed worker exceeded the Mine Safety and Health Administration’s (MSHA’s) permissible exposure level (PEL) of 90 dB(A) eight-hour time-weighted average (TWA8), laborers, mechanics, oilers, helpers, pickers and greasers are the workers most likely to be exposed to hazardous sound levels and to thus develop NIHL over time

By G. G. Morgis

In carrying out the provisions as set forth by an Act of Congress (36 Stat. 369) approved May 16, 1910, effective July 1, 1910, and the amended Act of February 25, 1913, (37 Stat. 681), the Bureau of Mines, among other activities, conducts inquiries and scientific and technologic investigations concerning mining with a view to improving health conditions and increasing safety and disseminates the general information gained by these studies. Through the medium of these publications, the causes as well as the methods that have been found most satisfactory in combating undesirable conditions are brought to the attention of the mining industry. This bulletin describes health and safety reports that have been published for the period July 1, 1955, through June 30, 1961. Technical Paper 705 issued in 1948 contains a listing of all Bureau of Mines publications dealing with health and safety in the mineral and allied industries from 1910 through 1946; Bulletin 558 contains a bibliography of such reports that were issued from January 1947 through June 1955.

Jan 1, 1962

By Joseph A. DeCarlo

This publication presents statistical data on oven-and beehive-coke plants in the United States. Information on the carbonizing capacity of the coke industry is important because of the close relationship between the coke industry and most of the other basic industries of our country. Coke is an essential-raw material in pig-iron production; also, coal-chemical materials are used to make fertilizers, paints, plastics, synthetic rubber, explosives, detergents, nylon, pharmaceuticals, dyes, and many other useful products necessary to sustain and improve the high standards of living in our country. Oven-coke plants in the United States on December 31, 1958, are tabulated in table 1. This tabular presentation shows the location, classification, number and type of ovens, annual coke capacity, coal chemicals produced, and name and address of parent company for each individual coke plant. About 86 percent of the capacity of slot-type coke ovens in the United States is owned by iron and steel companies. In most of these plants the coke ovens are integrated with the blast furnaces to facilitate transportation of raw materials for steel making. This has resulted in large coke plants, and the average annual coke capacity of "furnace" plants in 1958 was 1.3 million tons. Nonfurnace or "merchant" plants include coke plants associated with chemical operations, gas utilities, as well as coke plants that produce metallurgical, industrial) and residential-heating grades of coke and coal-chemical materials for sale on the open market. These plants ordinarily are not as large as furnace plant~ and annual coke capacity of merchant plants in 1958 averaged only 500 thousand tons. At the end of 1958 there were 55 furnace plants and 22 merchant plants.

Jan 1, 1959

By James C. Barker

In 1981 and 1985-1986, the Bureau of Mines conducted orientation studies of marine placer platinum-group metals (PGM). PGM are derived from the Goodnews Bay ultramafic complex and magnetic surveys show that the complex extends offshore at least four mi. The present seafloor was an emergent foreland as recently as 8000 years ago. High-energy ocean processes are transporting and depositing sediment such that PGM-bearing materials are reworked and later masked by barren littoral drift. Exploration targets include 1) placers formed since present transgression began, and 2) ancient marine and drowned fluvial deposits. Additionally, there is evidence of PGM solution transport and accretion. At least minor values of PGM in Recent lag-type placers and possible submarine strands are concentrated along an offshore scarp incised through glacial deposits into the preglacial surface between Flat Cape and Red Mountain. Other Recent PGM-bearing features include Flat Cape shoal, Chagvan Bay, Salmon River delta, and modern beaches. Ancient placers include possible N-S fluvial systems 2 to 3 mi offshore, a nearshore scarp 50 ft below sea level, and strands adjacent to projected ultramafic bedrock slopes. The existance of ancient placers is dependent on depth of glacial erosion. SEM studies show PGM are principally isoferroplatinum and osmiridium, with minor sperrylite, moncheite, and platiniridium. Gold is a co-product, and concentrates comprise chromite, ilmenite, and magnetite. Beneficiation tests successfully concentrated precious metals from natural blacksand accumulations, but failed to concentrate low-grade lag gravels.

Jan 1, 2011

By Galen G. Waddell

This report describes a method of measuring and analyzing the initial deformation which occurs in the medium surrounding a mine accessway as the opening is created. Discussed are (1) the hypothesis upon which the research is based; (2) the in situ rock-deformation measuring equipment developed; (3) the field tests, consisting of measuring the deformation of the medium around two 4-foot-diameter raise bores as the boring progressed; and (4) a finite-element technique to correlate theoretical with experimental results, using elastic theory. Described also are the raise-bore operation and performance. The instrumentation developed proved to have the sensitivity and resolution necessary to measure rock deformation around a full-scale raise bore during excavation. Tests show the relationships of rock deformation to progress of the raise boring and to time. The initial deformation of the opening appeared to be elastic. Using the deformation records and an estimated field stress, the modulus of elasticity was determined for the rock mass. In addition, the importance of this type of measurement in assessing support-problem areas is discussed.

Jan 1, 1971

By Terry McMahon

This Bureau of Mines report describes the rock burst problem and measures being taken for its alleviation in the deep underground mines of the Coeur d?Alene Mining District in northern Idaho. The geologic features that contribute to rock bursting in that area are discussed and briefly compared with similar features in other burst-prone mining districts throughout the world. Early investigations to understand and control rock bursting are reviewed, and the mechanics of bursting are discussed in terms of the seismic events that produce them. Sources of strain energy, rock failure mechanisms, and the conditions necessary for the release of seismic energy are covered in detail. Rock burst research in the Coeur d'Alene District is described. Included are discussions of the microseismic method as both a research tool and as a rock burst monitoring system, rock destress blasting and preconditioning methods for rock burst control, and stoping methods currently being developed to reduce rock burst hazards.

Jan 1, 1988

By E. P. Youngman

Zirconium, formerly distinctly a rare element, is rapidly becom- ing of rather extensive commercial importance. Economic features of the zirconium industry, together with general information regarding the metal and its compounds, are discussed in a separate paper, to which this paper is a supplement. In addition to giving a brief discussion of the four or five de- posits that so far have proved to be commercial sources of the element, this circular summarizes available data (including some hitherto unpub lished material from the files of the Bureau of Mines) upon other occur- rences, including many of scientific interest only, of the two commercial. minerals, zircon and baddeleyite, and also data upon some of the minor minerals, such as eudyalite and cyrtolite, which have attracted addition- al interest in recent years because they are frequently richer in hafnium than the more common zirconium minerals.

Jun 1, 1931

By Leo A. Schrider

This report analyzes the successful low-pressure gas drive in the Keener sand of the Bonds Creek oilfield, Pleasants and Ritchie Counties, W. Va.) and predicts its future performance. Core analysis from two wells and electrical and radioactivity logs were used to evaluate the reservoir characteristics. Production records over a 37-year period indicate that over 240,000 barrels of oil have been produced from the Keener sand by low-pressure gas injection. Decline-curve analysis shows that 165,000 additional barrels should be recovered from 108 acres of productive sand by continuing this secondary-recovery method.

Jan 1, 1966

By O. S. North

As recently as the late 1920's there Were few indications that a 15-million-dollar-a-year industry would ever grow out of the mineralogic curiosity vermiculite. Today, it is an important industrial commodity, used primarily as an insulating material and lightweight aggregate, but with a wide range of other applications. The quantity of crude vermiculite produced and used in the United States increased 14-fold in the 17 years between 1935 and 1951. The vermiculite minerals are of secondary origin, formed by hydrothermal alteration of an ultrabasic igneous rock, generally pyroxenite, or by alteration of phlogopite or biotite mica or possibly other similar minerals. According to different authorities, vermiculite may originate either by direct hydrothermel means, by the weathering of biotite or phlogopite, or by a combination of these two agencies. Vermiculites frequently occur at or near the contacts of an acid intrusive rock, especially a pegmatite dike, with a basic or ultrabasic country rock.

Jan 1, 1953

By James L. Elder

The Bureau of Mines and the Alabama. Power Co. jointly conducted a first experiment in underground gasification of coal at Gorgas, Ala., during the fall and winter of 1946-47. This preliminary experiment showed that it was not difficult to maintain combustion of coal underground, and that coal in place could be completely gasified. It was noted that the high temperature developed by the gasification of coal in place brought about changes in overlying strata that appeared to be favorable to the process. The high temperatures caused the roof rock to become plastic, to expand, and to settle down on the mine floor directly behind the reacting coke face. These results were promising enough to warrant further investigation of the process. It was believed that if this action could be controlled properly with roofs of similar composition, it would tend to force the gas-making fluids underground against the coal faces. Plans for the second experiment were based in part on this favor-able roof action, and the successful operation of the planned initial straightline passages depended on this fact. Gorgas was chosen as the site for the second experiment for the following reasons: A tract of coal land of sufficient size was available and isolated from the main body of coal; the roof rock was similar in composition to that encountered in the first experiment; and the overlying strata were thick enough to eliminate some of the operating difficulties that had been encountered, In addition, power, water, and machine-shop facilities as well as an adequate supply of labor were available in this area, and the friendly cooperation of the Alabama Power Co. further recommended this site for the planned experiment.

Jan 1, 1951

By McHenry Mosier

Mechanical loading, adopted long ago in open-pit, coal, and non-metal mines, was not used extensively in underground metal mines until the World War. In less than a decade it became standard practice in underground work in many mining districts. In 1924 the Missouri School of Mines and Metallurgy, in cooperation with the Federal Bureau of Mines, published a bulletin entitled "Mechanical Underground Loading in Metal Mines," which was prepared by Charles E. van Barneveld, mining engineer, Bureau of Mines.

Jan 1, 1940

By M. C. Irani

This Bureau of Mines report tabulates methane emissions from U.S. bituminous coal mines with daily emission rates of at least 100,000 cfd according to States, counties, and coalbeds. Most of the methane emitted is from mines in the Appalachian States. Total daily emission in 1975 was 216.3 MMcfd, compared with 227.0 MMcfd in 1971 and 214.5 MMcfd in 1973. Thirty counties in nine States hid daily methane emissions of 1 MMcfd or more. These emitted 93 percent of the total methane. The highest emissions were from Monongalia County, W. Va., which accounted for 18.9 percent of the total. This was followed by Marion County, W. Va., 9.6 percent; Buchanan County, Va., 8.3 percent; Jefferson County, Ala., 6.1 percent; and Washington County, Pa., 5.9 percent. The Pittsburgh coalbed emitted 45.7 percent of the total methane, followed by the Pocahontas No. 3 coalbed with 12.9 percent. The report lists 196 mines, of which 60 had daily methane emissions of 1 MMcfd or more. Included in this compilation are the identification and thickness of the coalbed, methane emission, coal production and ventilation rates, number of drifts, shafts, and slopes used for ventilation purposes, shaft depth, age of mine, and gas-to-coal ratio.

Jan 1, 1977

By J. E. Chilton

A technique for use in underground coal mines measures the response times of machine-mounted methane monitors. This technique uses a calibration cup to deliver gas to the sensor head to measure response times. For comparison, in the current study, response times were measured by placing methane sensor heads in a specially designed test box where they were exposed to an atmosphere containing a constant concentration of methane. Response time readings measured in the test box were shorter than the readings obtained using the calibration cup. The response times measured in the test box were comparable for sensors from three different manufacturers. The effects of dust cap and flame arrestor design on response times were also evaluated using the test box.

By M. P. Hardy

Copper-Nickel ores in northeastern Minnesota could establish a new industry in a region where underground mining has not been active. This study reviews geotechnical data relevant to the selection and design of underground mines in this region and by numerical structural analysis evaluates the importance of some geotechnical parameters to mine method selection. Because of the rapid development of computer modeling many new techniques have become available for modeling rock mass behavior in recent years. An overview of these methods is presented and their applicability to mine design reviewed. Methods included in this summary were the differential continuum models, such as finite Pint and finite difference, integral continuum models, such as boundary element, displacement discontinuity and boundary integral equation methods, and discontinuum methods such as the distinct block model. The displacement discontinuity method was used to evaluate the influence of geotechnical parameters on some aspects of mine design. Three problems; room stability, pillar stability on a weak inclined contact and sill pillar thickness influence on sill pillar stability, were analyzed to evaluate the relative importance of insitu stress field and joint properties on design. It was concluded that for stability analysis the initial horizontal stress is of most importance in all aspects of design. The position, orientation, persistence and strength of joints is also of primary concern. In a more general sense, however, it was concluded that detailed geotechnical parameters have much less influence on mine method selection than more general factors such as rock quality, initial stress state, orebody shape and economics.

Jan 1, 1978

By Paul M. Price

The Mouat mine, Nye, Mont., was reopened in 1953 by the American Chrome Co. under a Defense Minerals Production Administration contract. Operations were terminated in 1961 after completion of the contract. Mining methods employed during this period are described in detail, and cost data are presented by years for 1953 through 1959. Ultramafic rocks of the Stillwater complex in Montana contain the largest domestic resource of chromite, and the Mouat mine has been the largest producer. Mine reserves were estimated in 1960 to be about 4.4 million tons containing 22.5 percent Cr2O3. The chromite deposits occur as a series of overlapping bands or lenses roughly paralleling the steeply dipping layers of the complex. Only two of the chromite layers have proven to be of economic importance. One layer is 2 to 16 feet wide; the other is 3 to 8 feet wide. Shrinkage stoping was generally used throughout the mine, but various methods of ore breaking, stope drawing, chute construction, etc., were tested to improve output and lower costs. Long-hole stoping proved to have limited use. Breasting down benches, developed outward from the center of the stope with air-leg drills, was satisfactory only in wider stopes. At the close of operations, the company had standardized the use of lightweight stopers to advance a flat back by breaking from a centrally located face. Mining costs were reduced 47 percent during 7 years of operation.

Jan 1, 1963

By G. K. Derby

Five different types of drilling systems were developed under the flexible drill program that was initiated by the Federal Bureau of Mines to protect roof bolter operators. The systems were designed for underground coal mines with seams as low as 30 inches, and with roof bolts longer than the height of the seam opening. Four of the developed systems were true flexible drills; the fifth was a remote-controlled, automatic rod changer concept. Only two of the five firms successfully completed testing requirements under the original contracts: BendixCorp.,4 with a true-flex drill; and Ingersoll-Rand Research, Inc., with the rod changer concept. The Bendix drill was rated best, and the Ingersoll-Rand drill was rated second. Because of the closeness of the ratings and the vast differences in the two development concepts, both systems had sufficient potential to justify further development funding for design updating and testing. Also, both systems warranted consideration for inclusion into other ongoing development projects under both safety and energy directed programs.

Jan 1, 1978

By Kenneth L. Cashdollar

This report describes three types of optical dust probes that have been designed, built, and tested by the Bureau of Mines. Each of the probes measures dust cloud concentrations by the attentuation of light. The first is a single-path-length probe, the second is a double-path-length probe, and the third is a single-path-length probe that employs jets of air to keep the windows of the light source and detector free from dust coating. The theory of operation and the calibration procedures for each of the probes are described. The results of the Bureaus laboratory, mine, and field tests of the probes are also reported.

Jan 1, 1981