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By Glenn A. Hazen

This report presents a stress investigation of four coal pillars located under two depths of cover. Each coal pillar was instrumented with ten load cells designed to measure coal pressure during initial and secondary mining. The problem considered was one of uniform triaxial stress as a large coal pillar was loaded under a thick limestone bed. Special attention was given to pillar design procedure. Unconfined uniaxial compression tests were conducted for coal specimens 7/8 in., 2-1/8 in., 3 in., and 4 in. square with length to square side ratios of 1/2, 1, 1-1/2, and 2. Stress-strain curves were recorded. Six specimens were tested at each size. Results show that a coal pillar is composed of an inner zone which is highly loaded plus a region around its perimeter which has lost its elastic strength. The bearing capacity of a coal pillar consists of elastic and crushed coal response: The failure strengths have been determined and will be useful in coal recovery, mine design, and mine safety.

Jan 1, 1975

By J. F. Barkley

Under the procedure of the American Standards Association, with the American Society for Testing Materials as sponsor, the Sectional Committee on Classification of Coals has arrived at the classification of coals by rank as shown in Table 14/. The standard explains the term "agglomerating" used for classification under physical properties, as follows: Agglomerating Index. - Coals which in the volatile-matter determination produce either an agglomerate button that will support a 500-g weight without pulverizing, or a button showing swelling or cell structure, shall be considered agglomerating from the standpoint of classification.***. Pending the adoption of a method by the American Society for Testing Materials, the coke-button grading test5,/ afforded by the examination of the residue in the platinum crucible incident to the volatile matter determination, shall be used.

Jan 1, 1937

By D. J. Dollhopf

The specific objective of this three year study is to investigate the means of reestablishing non-polluted hydrologic systems in areas where surface mining directly impacts shallow ground-water resources. The research area chosen for the study is located near Colstrip, Montana it a new mine site where chemical analysis of core samples from the overburden suggested that excessive concentrations of several elements would he encountered during the mining process. This report discusses local vegetation; soils; and regional geology, and hydrology. Stratigraphic cross sections and regression analyses were used to study the litho-chemical relationships in the overburden. Cross sections indicated Inimical material may be related to both rock tune and position within the overburden profile. In overburden zoness where clay content was high, there was a greater probability that Pb, Cu, Ni, and Mn concentrations would also be higher than average; similarly, the likelihood of overburden exceeding a suspect level became less as the sand content increased. Highest value, of conductance were usually found within a few meters of the surface. High concentrations of clay, nickel, and zinc were frequently found directly above and below the Rosebud coal. Regression analysis indicated overburden SAR was predictable with only a Na analysis. A strong relationship also existed in the overburden between conductance, Ca, and Mg.

Jan 1, 1977

By Wiliam L. Crentz

The importance of Somerset County, Pa., as a coal producer is due in large measure to the presence reserves of low-volatile bituminous coals. Although many coal beds of minable thickness are present, the important reserves are to be found in those beds underlying the Pittsburgh bed. The Kittenning beds and Freeport beds, which are responsible for the bulk of the present coal production in Somerset County and contain the largest reserves to meet future coal requirements, are usually thin and entirely free from impurities. The Pittsburgh bed, which has been such an important coal deposit in the coal areas immediately west and south of Somerset County, is of secondary importance in this county. Although generally rather friable, Somerset County coals have enjoyed wide receptability as excellent coals and to some extent have been utilized in the metallurgical market.

Jan 1, 1951

By Kenneth R. Maser

This report describes the development of a system which modifies an existing fly ash-foam remote mine sealing technique to make it capable of impounding water in a fire zone. The modification involves blending equal quantities of fly ash and bentonite to form the bulk of the seal, and blending a thin layer of fly ash and Huron Regulated Set Portland Cement (RSPC) as a coating. The modification replaces the pure fly ash approach, but continues to use a froth foam topping to complete the seal. The modified material system is implemented with minimal complexity by adapting a "Y" connector to the existing delivery system. Each bulk hauler (fly ash and bentonite, or RSPC) will pump into one leg of the 'Y'; and the blending will be controlled by two pinch valves. The development effort has involved an evaluation of potential material systems by using small sample, quarter scale, and full head tests. The small sample tests measured the basic properties of a large number of selected material combinations. Property measurements included capillarity, permeability, shrinkage, and shear strength. As a result of these tests, particular combinations of fly ash-bentonite and fly ash-cement were selected for scale model testing in a 1 /4 scale test facility. These tests simulated, in a scaled manner, the water rise and total head which would be experienced by a seal. The tests indicated that shrinkage in the fly ash-cement combination would always result in leakage; whereas, fly ash-bentonite mixes were impervious to water.

Jan 1, 1974

To provide longwall operators with a method to predict methane emissions from panels with increased face width.

Jan 1, 1997

By Constantine C. Popoff

The Hermada antimony deposit is in the Sewtooth Range in southwestern Idaho, about 77 miles by road northeast of Boise. Stibnite mineralization occurs over an area one mile wide from west to east and two miles long. It is locally referred to as the Swanholm district. In 1947 high- grade stibnite ore was discovered on the East Fork of Swanholm Creek. Since then, ore in commercial quantity has been produced by the Hermada Mining Co. The total output for 1947-50 was about 5,000 tons of ore, containing 640 short tons of antimony metal.

Jan 1, 1953

By A. B. Hooker

Gassy mines require daily inspections with methane detectors to test for the presence of methane. Although in many manes it may be sufficient to know that there is no methane present or that its percentage is below a certain amount, it is desirable and often necessary to determine definitely the percentage of methane at the working faces and in the various air currents. The Bureau of Mines recognizes two general types of portable methane detectors, namely; 1. Methane detectors by which the presence of methane may be detected and its approximate percentage estimated.

Jan 1, 1929

By H. E. Heide

The serious shortage of domestically produced asbestos during the war prompted the Bureau of Mines to investigate reported asbestos deposits in Alaska. The most promising' appeared to be these in the Cosmos Hills and Jade Hills areas along the Kobuk River in northwestern Alaska. The deposits along the west side of Shungnak River, a tributary of the Kobuk River, were the first to be investigated by the Bureau, in the summer of 1944. Four bulldozer trenches were excavated, from Which a 2-ton sample was taken. This sample was shipped to Rolla, Mo., for testing in the Bureau of Mines laboratory. In the summer of 1945 an investigation of asbestos deposits on Cosmos Creek, also a tributary of the Kobuk River, was begun; the work was completed during the field season of 1946.

Jan 1, 1949

By Frank D. Lamb

"INTRODUCTION The use of beryllium and its alloys has come into prominence in the last 15 years and increased considerably during the war. In contrast to other light metals, such as aluminum and magnesium, beryllium is relatively hard, has a high melting point (1,285° C.), and other properties that make it resemble steel in many respects. It has a specific gravity of 1.85, is only slightly heavier than magnesium (specific gravity 1.74), and is appreciably lighter than aluminum (specific gravity 2.7). Its lack of ductility prevents its use as a structural material, but this difficulty may be overcome in the future by the use of various alloy forms. The only important commercial alloy in which beryllium is used today is with copper. The addition of small percentages (1/2 to 2 percent) of beryllium to copper imparts properties to the alloy that make it desirable for use in springs carrying electrical current, particularly at high temperature. Many other uses of berylliam are known, and new uses are being found constantly that make the metal of increasing interest.Possibly the main factor preventing the use of more beryllium is the lack of a large source of beryllium ore. Many beryllium minerals are found as minor constituents of natural deposits, some of the more common ones being beryl (Be3Al2(Si03)6), chrysoheryl (Be A1204), helvite (3(Mn, Fe) Be Si04. MnS), and phenacite (Be2Si04). Of the known beryllium minerals, beryl is by far the most common and has been found distributed rather widely throughout the world. It usually occurs associated with granitic rocks and is commonly found as a constituent of granitic pegmatite."

Mar 1, 1947

By L. A. Readdy

Pilot Hole "X" was drilled to test the formations through which the ventilation shaft for the proposed U.S.B.M. demonstration oil shale mine would be drilled. The geologic formations encountered in this hole are discussed. Correlation of the geologic horizons encountered in this hole with those encountered in nearby drill holes was accomplished by the use of geophysical logs. Data on the geophysical interpretations are provided. The anticipated geotechnical characteristics of the geologic units encountered in Pilot Hole "X" are described.

Jan 1, 1977

By Oliver Bowles

"Score of the Bureau's Investigations.There has been outlined in a previous report* the results obtained regarding the adaptability of pulverized waste slate as a filler in road asphalt mixtures. As pointed out in that report the percentage of waste at slate quarries is very high, and the Bureau of Mines has undertaken the problem of discovering new and enlarged outlets for the waste material.Many products such as paper, rubber, road asphalt, floor coverings, paints, etc., require as one of their important constituents a considerable percentage of finely pulverized inert mineral matter to give ""body"", to obtain the desired consistency, or to supply the necessary wearing or other qualities demanded. Such materials are known as ""fillers"". The possibility that slate flour might be used as a filler with advantage in several products other than road asphalt led the Bureau to undertake further investigation.The Importance of Discovering Advantageous UsesIt has been found that in some products slate may be substituted for materials now in use without any marked effect on the quality of the products. A wider use of slate in such products could result only from a definite price advantage as compared with other fillers. Mile it is probable that waste slate may be placed on the market at prices which will encourage its wider use, it is evident that a waste slate utilization industry can never attain sufficient magnitude to definitely assist the slate producers unless it is demonstrated that some definite advantage in quality may be gained when slate is substituted for fillers now in use. The main purpose kept in view throughout the inquiry has been, therefore, to find advantageous uses for waste slate in order that both producer and consumer may be benefited."

Sep 1, 1921

By Judith L. Bolis

The Bureau of Mines estimated the potential availability of iron ore from 129 domestic and foreign mines and deposits in 25 market economy countries. The availability of four products on a total and regional basis was determined from demonstrated resources of 75.3 billion It. From the resources evaluated there are a total of 18.6 billion It of sinter fines, 4.9 billion It of lump ore, 14.7 billion It of pellets, and 820 MMlt of pellet feed potentially available at a 15-pct DCFROR, f.o.b. port. On a regional basis, at or below a total cost of $0.26 per iron unit there are 1.7 billion It, 2.8 billion It, and 186 MMlt of sinter fines potentially available from Brazil, Australia, and Africa, respectively. There are 825 MMlt of lump ore from Brazil and 1.4 billion It from Australia potentially available at or below a total cost of $0.24 per iron unit. There are 2.1 billion It of pellets potentially available from the United States at or below a total cost of $0.80 per iron unit, while 442 MMlt are potentially available in Brazil at or below $0.38 per iron unit. South America has 208 MMlt of pellet feed potentially available at or below a total cost of $0.28 per iron unit. While the resources of iron ore are more than adequate to satisfy demand, the future of the iron ore industry is very dependent upon changes in the world economy, and on the domestic scene, changes in the domestic steel industry and steel imports.

Jan 1, 1987

By Cavallaro. J. A.

This report presents the results of a washability study of 455 raw coal channel samples with special emphasis on sulfur reduction. These raw coals contained on the average 14.0 percent ash, 1.91 percent pyritic sulfur, and 3.02 percent total sulfur. The complete washability data are presented for each sample processed. A statistical evaluation is included for the coalbeds from which more than 10 samples were collected and for the geographical coal producing regions. A graphical summation is presented for the coal producing regions and selected coalbeds. Finally a similar statistical evaluation is included showing composited data interpolated at Btu recovery levels of 50, 60, 70, 80, 90, and 100 percent. Graphical summations are presented for the various coal producing regions. Generally, significant sulfur reduction is achieved if the coals are crushed to a finer size and the higher specific gravity increments are removed. If a 50-percent Btu recovery was acceptable, then 32 percent of the samples tested could be upgraded to meet the current Environmental Protection Agency (EPA) standard of 1.2 pounds of S02 emission per million (MM) Btu when crushed to 14-mesh top size and separated gravimetrically.

Jan 1, 1976

By G. A. Smyres

A GaC12--B2 l-eachtng procedure and meEal-recovery method for treating an arsenical Cu-Co sulfide concentrate was developed by the Bureau of Mines as an alternative to smelting, which is no longer considered an environmentally acceptable method for treating arsenic-containing ores. The procedure involved leaching in a CaC12 solution with CaC03 for 96 h at 26 pct solids (concentrate and CaC03), 1150 C, and a pressure of 50 psig (345 kPa) with oxygen. More than 98 pct of the cobalt and 97 pct of the copper were extracted, and 99.98 pct of the arsenic and 99.9 pct of the iron remained in the leached residue. A filtration rate of 2.9 gal/(ft2.h) [118 L/(m2.h)] and a cake formation rate of 36 Ib/(ft2.h) [172 kg/(m2.h)] were obtained by filtering reacted pulp at 1000 C. More than 99 pct of the copper in the pregnant solution was extracted as CuCl2 by golvent extraction with a new copper extractant. Copper was stripped from the loaded organic with a sulfate-chloride solution, which was used as the anolyte for electrowinning of copper in a membrane cell. Copper plate produced was more than 99.99 pct pure and requi.red 0.81 (kW'h)/lb Cu [1.78 (kW·h)/kg Cu]. Cobalt sulfide was precipitated at pH 3 with Ca(HS)2.

Jan 1, 1986

By Donald E. Redmon

This Bureau of Mines report reviews injury experience in the nonmetallic mineral industries (except stone and coal) for 1968-69. For each of the years, 23 tables summarize disabling work injuries by department, source of injury, extent of disability, part of body injured, and nature of injury. Correlative information on employment, worktime, and operating activity is also presented.

Jan 1, 1973

Lignite constitutes approximately 97 percent of the near-surface coal resources in Texas. The most significant bituminous resources are in the north-central and southern parts of the state. Coal reserves in Texas are estimated to be 13.7 billion tons, about three percent of U.S. coal reserves. The average thickness of coal seams mined in Texas is approximately eight feet. Texas gained primacy when its regulatory program was conditionally approved February 16, 1980; the program was fully approved June 18,1980. The state's Abandoned Mine Lands program was approved June 23,1980.

Jan 1, 1992

"The present and possible futures commercial production of potash from various sources in the United States is discussed below under the following heads:1. Potash from the saline lakes.(a),Nebraska lakes.(b),California lakes.(c),Other lakes.2. Potash as by-product from the cement kilns.3. Potash as by-product from the iron blast furnace.4. Potash from silicate rocks.(a),Feldspathic material.(b),Leucite rocks of Wyoming.(c),Sericite slates of Georgia.(d),Glauconite (greensand) of New Jersey.5. Potash from Alunite.6. Potash from organic sources other than kelp.7. Potash from kelp.In this discussion very little more than passing reference, if any, will be given to those projects which up to date have been de¬veloped only slightly, if at all, beyond the small scale laboratory stage, or for the development of which there appears to be very little financial and technical backing at the present time. Nether or not many of these proposed projects have merit can be determined only by an actual operating demonstration.Generally speaking, the potash industry of the United States has been hardly more than marking time since the armistice. This is, largely due to the fact that the consumers of potash have been expecting that heavy shipments of foreign potash to the United States would be resumed soon at somewhere near the pre-war prices, and they have not been buying domestic potash at present prices for many months. The result has been that domestic producers have been unable to sell their product at even cost and many producers of potash have been obliged to close down. Thu Nebraska lake plants were closed down in February. The California saline plants were operating at below capacity, and the only large alunite plant is closed down. Even the cement plants have little or no inducements to recover the potash being lost in their waste gases, and the production is very small at present."

Jan 1, 1919

Objective The Roof Monitoring Safety System (RMSS) introduced in late 1997 has been modified to improve durability and simplify the measurement of roof or rib movement. Greater knowledge about the stability of roof and rib rock is expected to result in safer conditions for the mine worker. Developing safety tools and methods is part of NIOSH’s mission to prevent work-related injuries and deaths. A mining operation with a proactive approach to control ground conditions is in a better position to make essential decisions related to mine development and take remedial actions in the event of roof or rib falls. Background Falls of roof and rib rock are responsible for a high number of mining injuries and fatalities. Visual inspections and the sound of breaking or cracking rock are often relied upon to indicate unstable roof conditions. In some mines, roof bolt holes are checked for separations or gaps with a scratch tool; this provides further information about the stability of the roof. Monitors such as the RMSS can confirm roof movement that was surmised only by eye or ear, or potentially detect movement that was missed by these means. An added safety feature of the RMSS is the capability of locating the measurement station at a distance from where the monitor is placed in the roof. Stone and other industrial minerals are the basic raw materials used in construction. Continuing economic growth and highway building in particular have resulted in record demand for stone. This high demand, coupled with increasing constraints on surface mining, have caused many new .stone mines to be developed underground. These new mines in many cases will be employing new and inexperienced miners who may not have the ability to recognize unstable ground conditions using just sight and sound. From the initial introduction of the RMSS, it was anticipated that improvements and modifications would occur. We correctly assumed that, once miners and operators were exposed to the monitor. suggestions would evolve. In one case, the RMSS was used to determine if an impact hammer used on a mechanical scaler was causing or increasing instability of roof rock. The test showed little or no movement resulted from this method of scaling under the particular conditions at this mine. In another instance, an operator needed to monitor the stability of a haulageway in a benched area that had very high ceilings. The RMSS requires a 2-in-diam hole for installation; however, only roof bolt holes of a smaller diameter were available, and it was impossible to drill new holes at that height. The operator attached a 2-in collar at the roof line and was able to install the RMSS. These examples illustrate the potential for further enhancements of this tool. NIOSH continues to seek additional candidate sites for use of the RMSS. As usage increases, we anticipate further refinements and additional applications. How It Works The new RMSS, cable, and read-out box are shown in figure l. The read-out box has a green light that stays lit until battery replacement is needed. The red light is set to conic on to indicate movement. The red light can he adjusted for increments of movement as low as .010 inches. The RMSS red light should not be considered as a primary or only means of determining the stability of roof or rib. It is intended to serve as a supplement to existing methods or procedures for determining stability. An overview of the RMSS components is shown in figure 2. Movement of rock layers within the mine roof is measured relative to a fixed-point calibration at the monitor housing. The housing contains a potentiometer, roller switch, plastic rack, and spur gear. Movements are detected by the transfer of electromotive forces

Jun 1, 2000

By William A. Beck

Bauxite was discovered in the Springvale district in 1916. About 16, 000 tons was mined in the period 1916 to 1922, but no bauxite mining has been done since that time. The Bureau of Mines explored for bauxite in the district from September 5 to November 18, 1943. During the life of the project, the Bureau of Mines obtained mineral exploration agreements covering a total of 11,330 acres from 50 property owners. A total of 388 holes were drilled on five of these properties and 164 samples were taken and analyzed. The Springvale bauxite district includes an area of about 30 square miles in the northwestern part of Randolph County, Ga. The village of Springvale is in the west central part of the district, and Cuthbert is 8 miles southeast of it (fig. 1).

Jan 1, 1949