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By Roy C. Bartholomae

This Bureau of Mines report presents the results of a laboratory investigation of coal cutting mechanics and noise. These experiments were performed using linear cutting apparatus that operates over a broad cutting speed range. The influence of several coal cutting parameters on the noise, force, productivity, and specific energy associated with linear cuts was ascertained. Some basic theoretical aspects of coal cutting mechanics and noise generation are discussed, and the results of the laboratory experiments are used to formulate analytical models of the coal cutting forces and noise. The analytical model for coal cutting noise is then generalized to account for the more important effects of rotary cutting. Based on the generalized model, an estimate of the sound pressure level at an operator's position is made for a typical continuous mining machine. It is concluded that by employing linear rather than rotary cuts, using deeper depths of cut, slower cutting speeds, and more efficient cutting tools, it is possible to reduce the level of coal cutting noise, as well as provide benefits to other important areas of health and safety in underground mining.

Jan 1, 1983

By C. H. Riggs

"INTRODUCTION The injection of gas into the McClosky limestone in the adjoining, Griffin and New Harmony field in Indiana and Illinois and resulting increases in oil and gas production from this zone ore described in this report.Since 1911, the use of compressed air or as to increase oil production by supplementing natural reservoir energy has been widely adopted, and has resulted in the recovery of much additional oil, which otherwise would have been left underground. In many of the newer oil fields, including Griffin and New Harmony, a part of the compressed residue gas from natural gasoline plants is returned to the reservoir as a secondary method to increase oil and gasoline production. Part of the injected gas is stored underground for future use.By presenting data on many secondary recovery operations in a series of reports 5-9/ the Bureau of Mines has sought to stimulate interest in secondary recovery as a means of increasing oil recovery and current oil production for wartime needs. Most of the elder fields in the United States produce oil from sandstone reservoirs, and probably more than 90 percent of secondary recovery operations have been developed in oil bearing sandstones. During recent years, the volume of oil obtained by primary methods from limestone reservoirs has increased steadily, but as yet little has been done to recover, by secondary means,,the large volumes of oil left in limestone reservoirs when primary methods production are no longer profitable. Because of inherent differences in the origin and nature of the pore spaces between sandstones and limestones and because of differences in permeability and fluid content, secondary recovery methods, which are successful in sandstone-reservoirs, are not always applicable to limestones. Not much he been written concerning secondary recovery operations in limestone reservoirs, and few data are available to assist operators in developing such secondary recovery projects."

Jul 1, 1945

By Thomas A. Davidson

The Bureau of Mines Helium Field Operations has developed a simple and accurate method for calculating the viscosity of gas mixtures. Only the composition of the mixture and the molecular weights and viscosities of the pure components in the mixture are required. The momentum fraction of a mixture is calculated from the composition. The fluidity is calculated as a quadratic function of the momentum fractions. The efficiency factor for transfer of momentum in collisions between bodies of different masses is derived and used with one empirical constant. The viscosity is the reciprocal of the fluidity. Results of the method are compared with 752 reported viscosities for 40 dilute binary systems at temperatures from -78 to 276.9°C. Using this method the average absolute deviation is 1.29%, the root-mean-square deviation is 1.99%, and the average deviation is -0.84%.

Jan 1, 2010

By John C. LaScola

The Bureau of Mines investigated coal storage silos to determine how gassy coal must be for methane accumulations in a silo to become hazardous and where such accumulations are likely to occur. Methane concentrations were measured in the open space above the stored coal pile, in the pile, and in the reclaiming area. No methane layering was found in closed-top silos. Reclaiming areas were as gassy as the top part of the silos. Coal samples were collected from the conveyors entering the silos in order to assess the gassiness of the coal. No simple correlation was found between the gassiness of the coal stored and the measured methane concentrations. However, at mines where the average 24-hour gas emission from the conveyor belt samples was 14 ft3/ton or more, fans or open tops were used. It appears that a large fraction of the methane released during storage remains in the void space between the coal particles.

Jan 1, 1980

By John P. Hansen

Batches of red or brown iron ore concentrates, weighing 100 or 200 grams, were reduced with gaseous reductants in a laboratory-sized fluidized-bed reactor. Using a loss of weight technique, the rates of reduction were measured and the effects of temperature, gas consumption, and gas flow rates were determined. Below about 725° C the rate of reduction was controlled by the chemical reaction at the reduction interface having an activation energy of about 10 kcal/g mole. Above about 725° C the rate of reduction appeared to be controlled by the flow of the gaseous reductant and therefore to be directly proportional to the flow rate. Above 725° C, hydrogen reduced the iron ore much faster than carbon monoxide. In gas mixtures, carbon monoxide or nitrogen reduced the hydrogen partial pressure and lowered the reaction rate proportionally. When present in large concentrations, carbon monoxide had a serious inhibiting effect on the reduction rate, probably owing to carburization and sintering of the reduced iron.

Jan 1, 1970

By L. C. IlsLey, E. J. Gleim

It is the firm belief of the Bureau's engineers that the introduction of electrical mining machines has done much to increase safety in mining as a whole . There can be no doubt but that the substitution of machine mining together with permissible powder for the method of " shooting from the solid " has been the means of saving the lives of many shot- firers . Machine mining also leaves the roof in a better condition as lighter charges of powder are required to bring down the coal . Thus the danger from falls of roof are lessened . It is recognized that every effort should be made to prevent all accidents due to the use of electrical machinery but it is felt that any action tending to limit the use of such machinery would be a backward rather than a forward step in the safety measures laid out to decrease the hazards in coal mining .

May 1, 1920

By S. M. Shelton

Ferrograde manganese ore or its equivalent is essential to the manufacture of every ton of steel produced; although it is well-known that there are largo deposits of low-grade ore in the United States, production of substantial amounts of ferrograde material from domestic sources presents a problem that becomes more and more critical as the stock piled ore is depleted through inability to obtain adequate supplies from foreign sources. Consequently, a program of laboratory and pilot-plant investigations designed to solve the problem of obtaining a domestic supply of manganese has been undertaken by the Metallurgical Division, Bureau of Mines. This paper is one of a new series that will include reports of results obtained in the various investigations conducted under the manganese program. The scope of the program and the organization that was set up to direct and supervise the work were discussed in the foreword of the first paper of this series, Report of Investigations 3506, Manganese Investigations 1. Concentration of Manganese Ores from the Drum Mountain District, Utah, by S. R. Zimmerley, J. D. Vincent, and C. H. Schack. Other reports will be published as the work progresses.

Jan 1, 1942

By Robert L. Virta

This U.S. Bureau of Mines paper discusses the structure of the talc industry, talc production, processing of talc ore, applications and demand for talc, and the outlook for the talc industry.

Jan 1, 1989

By W. R. Hardwick

This information circular describes open-pit mining methods and practices of the Bagdad Copper Corp., Yavapai County, Ariz. It is one of a series being prepared by the Federal Bureau of Mines on mining methods, practices, and costs in various mining districts of the United States. A brief history of the Eureka district and of early developments at the [gdad] mine is given, and the are deposit is described with particular emphasis on those characteristics (physical, economic, or engineering) that affected the choice of mining methods. Prospecting, exploration, and sampling and estimating the tonnage and grade are outlined. Development of the open-pit mine is shown. Mining methods, including breaking ground, primary drilling and blasting, secondary drilling and blasting, loading, transportation, engineering, and operating control, are described. A brief summary of mining equipment is given. Percentage of extraction, production rate, mine drainage and water supply, wage, contract, and bonus systems, safety and fire prevention, and the processing plant also are described. The last section gives a breakdown of such costs as are available for publication.

Jan 1, 1959

By S. M. Shelton

Tests employing various ore-dressing methods were made on a manganese wad ore from the W. A. Chinn property in the Batesville-Cushman district of Arkansas in an effort to develop a practicable procedure for the production of ferromanganese-grade concentrates. The ore body occurs as a bed approximately 7 feet thick in the residual clay of the Ferndale limestone formation5/. The crude wad ores are soft aggregates of various oxides of manganese, which are loosely bonded together. Hard lumps of high-grade ore are disseminated throughout the wad. Hausmannite, pyrolusite, and psilomelane are the principal minerals. Some clay is present, but most of the gangue consists of leached fragments of the original siliceous and calcareous rocks in which the manganese occurred. In addition, hydrated oxides of iron, which axe present, also must be considered as gangue. Definite phosphate minerals have not been identified.

Jan 1, 1942

By Fred Hodges

This paper describing the concentrator practice of the Hurley Plant of the Nevada Consolidated Copper Co. at Hurley, N. Mex., is one of a series of papers on milling methods and costs being prepared by the United States Bureau of Mines. The Hurley concentrator has a normal daily capacity of 13,500 tons of ore, and for the first four months of 1930 the heads of the concentrator averaged 1.32 per cent of copper and 3.14 per cent of iron. The recovery for this period was 83.98 per cent and the concentrates produced averaged 27.54 per cent of copper.

Jan 1, 1931

The purpose of the contract was to develop an improved coal mine dust sampler whose electrical-to-mechanical energy conversion efficiency would be superior to that of the presently available equipment. The electrical to (pressure) X (volume) conversion efficiency directly affects the size and weight of the air samplers. At least half of the mass of present equipment is composed of the rechargeable batteries. Any increase in efficiency will allow this mass to be reduced or the flow rote to be increased.

Jan 1, 1974

By F. R. Cattoir

This Bureau of Mines study investigated molten salt electrorefining for beneficiating low-grade, high-carbon ferrochromium products which can be readily produced from domestic chromite concentrates. A second objective was to refine commercial ferrochromium into low-iron chromium products. Electrorefining of both types of ferrochromium in molten CaC12-NaCl-CrC12, CaCl2-MgC12-CrCl2, or KC1-LiCl-CrCl2 electrolytes produced chromium-iron products with virtual elimination of other impurity elements and some lowering of the iron content, Over 90 percent of the chromium present in the feed materials was recovered. The electrodeposited products were upgraded further by magnetic separation techniques into chromium containing less than 5 percent iron. The technical feasibility of preparing a premium chromium product from a low-grade, high-carbon ferrochromium made from domestic chromite was demonstrated. Chromium virtually free of carbon, oxygen, and silicon from high-carbon ferrochromiums was produced. In addition, the amenability of three commercial grades of ferrochromium to electrorefining and magnetic separation for preparing chromium metal containing less than 5 percent iron was determined.

Jan 1, 1969

By David R. Alison

This study was conducted using field interview methods to determine the data and information requirements of the underground coal mining industry for improving mine ground control procedures in existing and future mines. The establishment of a central geologic and engineering information resource center with computer searchable abstract files that can locate and supply descriptive and case-study literature addressing specific mining problems is recommended. Research done under Bureau of Mines Contract J0395010, includes a Bibliography of Underground Coal Mine Ground Control Literature.

Jan 1, 1980

By Ernest L. Corp

First in a projected series on the use of flexible liners for support of underground mine openings, this report presents information obtained from an extensive review of the literature on this subject. It also includes results of some preliminary test work by the Bureau of Mines. Investigations thus far indicate that flexible liners offer numerous advantages over rigid-type sup-ports, By deforming in the direction of the applied stress, the stresses are redistributed from the liner to the surrounding material. The corresponding buildup of passive resistance in the direction of diametric extension causes an equalization of stresses around the liner, thereby enabling the liner to carry loads in a more efficient manner. However, additional experimental data are needed to establish design criteria that will permit maximum utilization of the flexible liner concept in mining. Testing of small-scale models, accompanied by measurement of free-field stresses in material surrounding the model, is recommended as the most suit-able approach to the problem. The experimental procedures necessary to such an approach are outlined in detail and a statistical design for the experiments is proposed. The report also describes a device developed by the Bureau for measuring free-field soil pressures to 1,000 psi and a technique for evaluating the response of the device.

Jan 1, 1967

By Ronald W. Stingelin

The geology of the roof of the Pittsburgh coal bed was studied and mapped in nine contiguous counties containing the bulk of the remaining reserves of this coal bed in the northern Appalachian Coal Basin. Drill core records from Belmont and Monroe counties, Ohio, Washington and Greene counties Pennsylvania, and Ohio, Marshall, Wetzel, Monongalia, and Marion counties, West Virginia provided the data for twelve computer generated regional geologic variable maps. Four of these geologic variables (overburden thickness, vertical distance to the rider coal, lithology at the five foot horizon above the roof of the mineable Pittsburgh seam, and the number of lithologic changes within the 30 foot interval above the roof of the mineable Pittsburgh seam) were used to estimate the risk of potential roof falls by a methological scheme developed during this study. A hazard zone risk map was developed showing a generalized regional trend of increasing risk from west to east across the basin. Mapping of individual geologic variables and mapping of hazard risk can be done at any scale. The accuracy of the mapping is primarily dependent on the density of the drill core records. Geologic feature maps and the hazard risk map contained in this report are reduced (1 :500,000 scale) versions of the larger scale (1 :62,500) maps prepared for the Bureau of Mines as map folios.

Jan 1, 1979

By Forrest T. Moyer

Frequency rates of injuries per million man-hours of exposure were improved during 1965 slightly to moderately over those of 1964 at metal mines, nonferrous reduction and refining plants, nonmetal mills, stone quarries and mills, sand and gravel operations, and slag operations. However, at metal mills and nonmetal mines the rates of occurrence of work injuries were less favorable. The severity rates of injuries during 1965 were better than in 1964 at metal mines and mills, stone quarries and mills, and slag operations. Conversely, severity rates were worse at nonferrous reduction and refining plants, nonmetal mines and mills, and sand and gravel operations.

Jan 1, 1966

By W. W. Adams

The safety record established by the coal-mining industry of the United States during 1934, although not as favorable as that for the previous year, was better than the record for any other year during the period 1930-34 for which complete figures covering fatal and nonfatal accidents at the mines are available. The number of accidents was 89.98 per million man-hours of employment compared with 86.74 for the year 1933, the latter being the lowest rate in any of the 5 years referred to. The rate was 105.60 for 1930, the first year covered by available data. Employment increased in 1934; the number of workers represented an increase of 8 percent over the year 1933, man-shifts of labor increased 16 percent, and the number of man-hours of labor increased 7 percent. The total number of man-hours of employment also exceeded the number reported for 1932, and was almost equal to the record for 1931.

Jan 1, 1936

By E. R. Maize

This report is the third of a series on convergence of roof and floor in coal mines and subsidence of surface that accompanies it. The first paper5/ dealt with extraction in a mechanized mine (Montour 10) having relatively short rib lines that retreat rapidly. The second dealt with extraction in a mine (Crucible) in which coal was loaded. by hand and in which the rib lines wore long and slow-moving. The present report deals with a mine (Gibson) in which conditions approximated those in the Crucible mine, except that the distance between room centers was considerably less and the pillars were narrower in consequence. Moreover, the average cover was less and the studies were made under the steep hillside of a stream valley compared with a gently rolling surface over the portions of the second mine studied. Gibson mine lies in the east-central hart of Washington County, Pa. , approximately midway between the Montour 10 end Crucible mines on a north-south line. A cooperative agreement covering the work was made with the Hillman Coal & Coke Co. through W. L. Affelder, vice president. This paper describes the methods used in the investigation, gives excerpts from the data obtained, and offers such generalizations as appear to be justified.

Jan 1, 1940

By Thomas J. Peters

A mineral survey of the Sill Hill RARE II area (No. 5304), covering 5,200 acres (2,100 ha) of the Cleveland National Forest, San Diego County, California, was conducted by the U.S. Bureau of Mines and the U.S. Geological Survey. This survey was in conformance with the Resource Planning Act (RPA) of 1974, as amended by the National Forest Management Act of 1976, to provide mineral resource information for study area classification. Bureau of Mines personnel made an economic appraisal of mineral deposits by searching pertinent geological and mining publications as well as U.S. Bureau of Land Management, U.S. Forest Service, and U.S. Bureau of Mines files and records. Known mines, prospects, and mineralized localities were examined during 1981, and sampling and mapping were done where warranted. The Geological Survey 'did geologic mapping, geochemical sampling, and geophysical surveys to aid this study.

Jan 1, 1983