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By A. W. Khair, L. D. Gehl

"This paper describes the mechanism of coal and rock cutting from quasi-static indentation through dynamic indentation to rotary cutting. The results indicate that during quas~static indentation, a crushed zone, and subsurface fractures develop. The crushed zone is a potential source of dust generation. Dynamic indentation produces a crushed zone due to the frictional resistance offered by the coal or rock during penetration of the bit. Confining pressure changes the mode of failure from tension to mixed tension and shear. The wider bit causes larger crushed zone and more dust generation. The rotary cutting is a combination of quasi-static and dynamic indentation which results in chip formation. 1. INTRODUCTIONThe trend from conventional mining to continuous machine-cutting of coal, using more productive machinery is inexorable. Intolerable levels of dust generated at the face is an indication of inefficient coal or rock cutting by these machines. The Federal Government of the United States paid about 11.7 billion dollars workman compensation to more than 470,000 miners with Coal Workers Pneumoconiosis (Newmeyer, 1981). Bieniawski and Zipf (1985) reported that annual benefit payments were about 2 billion dollars. The need for research m improving coal cutting 1s therefore paramount. The enactment of Health and Safety Act in 1969 in the United States triggered the initial investigation into coal cutting mechanism and cutting tool design. The European countries were also engaged in the same area of research, however, their emphasis was in the use of wedge shaped bits. In 1981, the United States Bureau of Mines commissioned the South West Research Institute to investigate the effect of operating parameters mainly on airborne respirable dust in order to provide a healthier and safer atmosphere for coal mine workers.A research program by the Department of Mining Engineering, West Virginia University, USA was initiated to study the fragmentation mechanism during coal/ rock cutting. The research program was divided into three areas of research, namely quasi-static indentation, dynamic indentation and rotary cutting."

Dec 1, 1995

By Ronald T. Mayerle

There are no producing or developing mines in the Rattlesnake RARE II area. Specific areas with mineral occurences are prospects for: 1) stratabound copper and silver in Belt sedimentary rocks on the northwest border of the study area; 2) base metal sulfides, in thin veins and shear zones in Belt sedimentary rock, and diabase dikes and adjacent metasedimentary rocks in the southern part of the study area; 3) barite in sedimentary rocks near Rattlesnake Creek and Sheep Mountain; 4) limestone near Rattlesnake Creek and Blue Point; and 5) silica in quartz veins near the headwaters of Rattlesnake Creek and Sanders Lake. Stone, sand and gravel suitable for construction material are in the study area; however, equal or better quality deposits are common throughout the region. The RARE II area has no known oil and gas, coal, or geothermal energy deposits.

Jan 1, 1983

By J. Roger Loebenstein

Demand for arsenic trioxide exceeded supply in 1978 and 1979, and the major domestic and foreign producers allocated available supplies to customers. Major demand has been from the cotton-growing and wood-preserving industries. Ample supplies of arsenic metal produced in the United States and Sweden were available in 1978 and 1979. Major demand for metal was from the automobile battery industry in Japan, Europe, and the United States. Legislation and Government Programs.-The Occupational Safety and Health Administration (OSHA), promulgated the final standard on the occupational exposure to inorganic arsenic, effective August 1, 1978.2 The need for the standard was a result of OSHA's conclusion that inorganic arsenic is a human carcinogen. The purpose of the standard was to minimize the incidence of lung cancer among workers exposed to inorganic arsenic. The maximum exposure to arsenic was lowered from the previous ceiling of 500 micrograms per cubic meter of air to 10 micrograms per cubic meter over an 8-hour time period. OSHA had originally recommended a ceiling limit of 4 micrograms per cubic meter in January 1975. Provisions of the new standard require exposed employees to wear respirators and undergo continuous medical monitoring. Other provisions establish regulated areas limited to authorized employees and require the construction of special lunch-room and worker hygiene facilities and the posting of signs and labels warning of the presence of arsenic. The new arsenic standard will have a significant economic impact on copper, zinc, gold, and lead smelters as well as consumers of arsenic trioxide. A number of copper companies have joined together to contest the standard in court. However, measures to comply with the standard have been initiated by ASARCO Incorporated at its Tacoma, Wash. plant.

Jan 1, 1980

By J. B. Littlefield

[A rulp has i~c+:r. ilrsi i,nsd Lo O~JPY:L~ e the mid~ol Llf;pin.5cr rll~!-t-.cxny)lin:: apparatus recently c',ov~-lo.pe;t by tL1e '.liro:ul of !dines- For th-is pilryoac, a po?.-iti~rs-nct.i?~. pvrni? t:,.;~t v:i.l.'l. :.-,,- #?,n c-noot'fl ;L flow nc possiY,].c? is dcni?.oYle. Flota.lS:r vnnc\-t:rre 1jl:~l~l: zrt iln~;xtJsY:or (2s thc:; n1lr.t ke tvrned at h ityh spet.d for rT:oot,c, o;?ey,;ltiori., ~nd at hi:,h s~ee(' the c8n:xcity oi' the s-n:r.llest piqt ott:~ir?:zk?e Is too la~-~:c. nir crrn'rle bler! in nt the intn?~, but t,he mm;nt o nor.;: l.o'q7r ir.:,l soon t ire:. the oyernt or]

Jan 1, 1938

By J. B. Littlefield

[A rulp has i~c+:r. ilrsi i,nsd Lo O~JPY:L~ e the mid~ol Llf;pin.5cr rll~!-t-.cxny)lin:: apparatus recently c',ov~-lo.pe;t by tL1e '.liro:ul of !dines- For th-is pilryoac, a po?.-iti~rs-nct.i?~. pvrni? t:,.;~t v:i.l.'l. :.-,,- #?,n c-noot'fl ;L flow nc possiY,].c? is dcni?.oYle. Flota.lS:r vnnc\-t:rre 1jl:~l~l: zrt iln~;xtJsY:or (2s thc:; n1lr.t ke tvrned at h ityh spet.d for rT:oot,c, o;?ey,;ltiori., ~nd at hi:,h s~ee(' the c8n:xcity oi' the s-n:r.llest piqt ott:~ir?:zk?e Is too la~-~:c. nir crrn'rle bler! in nt the intn?~, but t,he mm;nt o nor.;: l.o'q7r ir.:,l soon t ire:. the oyernt or, ]

Jan 1, 1938

By Seth C. Schaefer

[As part of the Bureau of Mines effort to provide thermodynamic data for advancement of mineral resources technology, the standard Gibbs energies of formation (?G°f) of MnS (manganese sulfide) and Fe0.9 S (pyrrhotite) were investigated with a high-temperature galvanic cell employing stabilized Zr02 (zirconia) as the electrolyte. Potential measurements were obtained for the cell Pt, MnS, MnO, S02 (g, 1 atm)//Zr02//02(g, 0.0114 atm), Pt with the overall cell reaction MnS (s) + 1.5 02 (g, 0.0114 atm) = MnO (s) + S02 (g) . (1) These results give the standard Gibbs energy of formation of MnS for the reaction Mn (s) + 0.552 (g) = MnS (s) (2) ?G°f = -66.487 + 15.19 x 10-3T±0.207 kcal/mole (896.4 - 1,208.1 K) (3) where temperature (T) is expressed in kelvins. Similar measurements were obtained for the cell Pt, FeO .9S, Fe304 , S02 (g, 1 atm) //Zr02//02 (g, 0.0114 atm) , Pt with the overall cell reaction 10/3 FeO .9 S (s) + 16/3 02 (g, 0.0114 atm) = Fe.,04 (s) +10/3 S02 (g). (4) These results yield the standard Gibbs energy of formation for the reaction 0.9 Fe (s) + 0.5 S2 (g) = Fe0.9 S (s) (5) ?G°f = -35.229 + 12.67 x 1073T+-0.104 kcal/mole (839.5 - 1,086.6 K). (6) A third-law analysis of MnS data yields a standard enthalpy of formation (AH°f) for the reaction Mn (s) + S (rh) = MnS (s) (7) ?H°f298 = -51.16±0.21 kcal/mole (8) A similar third-law analysis for Fe0.9S data yields a ?29°f298 for the reaction 0.9 Fe(s) + S(rh) = FeO .9S(s) (9) ?HO\°f298 = -24.01±_0.15 kcal/mole. (10) ]

Jan 1, 1980

By Jeanne A. Zimmer, Brad Smith, Steve Viles, Andrew B. Cecala

A recent report evaluating silica exposure levels in the metal/nonmetal mining industry noted that bag packaging and loading are some of the occupations at the greatest risk. In addition to dust problems, the bag-stacking process is labor intensive, making lost-time injuries common due to back fatigue and strains. During the bag-stacking process, a significant amount of dust can be generated, mainly from product on the outside of the bags and from dust escaping the bag valve upon impact of the bag on the pallet. In an effort to address dust-exposure and back-fatigue issues, Malvern Minerals Co., Hot Springs, Ark., made two major improvements to its ground silica stacking facility. First, the company purchased a semi-automated bag palletizing system (Figure 1). With this system, the bag stacker does not lift the bags, but slides them across a metal table. Small jets of air exit through perforations in the table top (similar to an air hockey game), allowing workers to more easily slide each bag into the proper position. After each layer of bags is completed, the table slides open, and the entire layer of bags is loaded onto an underlying pallet. The table then closes, readying it for another layer of bags. After the entire pallet is loaded, the unit delivers the pallet to a shrink wrap and forklift pick-up area. In addition to this semi-automated palletizing unit, Malvern Minerals purchased an Overhead Air Supply Island System (OASIS) to lower the bag stacker's dust exposure. The OASIS takes outside air, directs it through MEASURING RESPIRABLE DUST The bag stacker's respirable dust exposure was monitored using a RAM-1 instantaneous dust monitor to evaluate the impact of the various changes on the palletizing process and dust-control equipment. The bag stacker wore a vest that held the 10-mm Dorr-Oliver cyclone, which classifies the respirable portion of dust. Flexible tygon tubing was used to connect the cyclone to the RAM-1 dust unit, allowing the bag stacker to perform the palletizing process with minimal interference. The RAM-1 measures respirable dust concentrations by light scattering with a sensing chamber. This device closely simulates gravimetric measurements when calibrated for a specific dust. This instrument is ideal for comparative evaluations, as was the case in this study. Since the RAM-1 is not an MSHA-approved instru¬ment for dust compliance sampling, the dust concen¬trations listed in this article should be used as a com¬parative value of respirable dust concentration and not to determine actual dust concentrations from a com¬pliance standpoint.

By Slavoljub D. Maksimovic

At some coal mines, methane gas is released during raise drilling. At the request of the Mine Safety and Health Administration (MSHA), U.S. Department of Labor, the Bureau of Mines conducted ventilation surveys at different raise drill sites to assess various methods of reducing methane concentration. The resulting data indicate that raise drill shaft cavities are ventilated by air compressors, vacuum pumps, auxiliary blower fans, and free intake air from the surface. The compressors, pumps, and fans operate simultaneously or separately. At the bottom of the shaft cavities, ventilation is controlled by regulators and airlocks. Methane is monitored, measured, and periodically sampled on the surface, at the bottom, and at different levels in the shaft cavities. Maximum concentration of 3.5 percent was measured in one shaft in West Virginia. Air velocity down the raise drill shafts is always very low, Maximum recorded air down the drill stem was 3,000 cfm, which can be increased by adding air compressors. The best way to ventilate shaft cavities is through the simultaneous use of air compressors and vacuum pumps. If the methane concentration cannot be reduced with additional compressors, then the inside diameter of the drill rod should be increased, or larger pilot hole drill bits should be used.

Jan 1, 1981

By T. Kessler

The purpose of this investigation was to evaluate the application of a spark-source mass spectrograph equipped with a spinning-electrode system for the study of various high-molecular-weight materials derived from coal. Conclusions from the investigation of anthracene, phenanthrene, chrysene, coronene, truxene, a coal-tar pitch (800 to 850 C softening point), and anthracene-chrysene synthetic mixtures follow: 1. Simplified mass spectra of anthracene, phenanthrene, chrysene, coronene, and truxene, from which the molecular weights were easily determined, were obtained by the spinning-electrode system. 2. Eight structural types having molecular weights from 178 to 252 corresponding to compounds previously observed in an electron impact mass spectrum of a coal-tar pitch sample were affirmed by this technique. 3. Mass spectra obtained from synthetic mixtures of anthracene and chrysene demonstrated that the technique is applicable for semiquantitative analysis.

Jan 1, 1967

By Alton B. Cook

Equipment has been designed and fabricated for study of the vaporization of oil during gas-cycling operations, A sand-packed steel tube, which can be rotated to minimize gravity drainage, is used as a model oil reservoir. A minute windowed cell at the discharge end of the tube through which the liquid-gas interface may be observed, makes possible the separate removal of produced free gas and gas-saturated oil. The operation of the model oil reservoir, and auxiliary equipment, are described by use of a schmatic flow diagram. Details of the specially designed equipment are illustrated by isometric and pictorial drawings, and a description of the experimental procedure is given.

Jan 1, 1959

By L. E. Geyer, W. W. Adams, M. G. Parry

"More than 73 million pounds of rock dust were used by the bituminous-coal-mining companies in the United States during 1930 to present or limit loss of life and destruction of property from explosions of gas and coal dust in underground mining operations, according to statistics compiled by the United States Bureau of Mines from reports furnished by mine operators. The mines using rock dust produced 65. 691, 753 tons of coal during the year, more than 30 percent of the total production of bituminous coal from underground mines in the United States that year. Although only 382 out of a total of 5,629 active underground bituminous mines applied rock dust to underground working as a precaution against explosions, they were chiefly the larger producing mines, employing 25.4 percent of all of the underground bitumious mine workers in the United States and accounting for 27.4 percent of the total number of man-hours worked underground at bituminous mines.a summary of the reports for the 382 mines using rock dust showed a total production of 96,691,755 tons of bituminous coal, 89,503 men employed underground, and 129,718,965 man-hours worked by the underground employees. (See tables 1 and 2.) These mines averaged 8.76 pounds of rock dust per ton of coal shown by reports from 385 mines using rock dust in 1932 (See table 3.)"

Nov 1, 1935

By D. Harrington

"While distribution of air currents to working faces is a necessity in coal mines, especially those having explosive gas, advancing faces in metal mines rarely have circulating air other than the ordinarily inadequate amount supplied through the compressed air system. Even where comparatively large quantities of air pass through main mine shafts and levels. whether the circulation is actuated by fans or by natural ventilation, only occasionally can a metal mine be found where any considerable percentage of the ""blind ends"" has circulating air of sufficient velocity to be measured by an anemometer or even be discerned by deflection of flame of candle, or of acetylene lamp; and unfortunately these ""blind ends"" include nearly all of the places from which rock is taken.During several years study of metal-mine ventilation in various mining districts of the United States, it has been found that in some mines many of the workers in ""blind ends"" practically continually breathe air with 0.02 to 0.04 per cent of CO gas from unremoved fumes from explosives; in other mines CO2 chiefly from timber decay and breathing of men, is so high that a candle will not burn though usually the acetylene lamp will, hence oxygen is below 17 per cent but above 12 per cent; in some regions CO2 from strata fills the entire mine forcing cessation of work; in other mines in dead ends, gases such as nitrogen, H2S, SO2, etc., are found under some conditions. In many regions with hot rock or water (especially in deep workings) men in blind ends must work with little or no circulation, in air above SO degrees F. and even above 90 degrees, relative humidity only too frequently being around 100 per cent; in other regions workers in blind ends in practically ""dead"" air must continually breathe enormous quantities of finely divided rock dusts. All of the above conditions are decidedly harmful to health and prevent the worker from delivering anything approaching an adequate quantity of work, and in addition, some of these conditions have direct or indirect effect in bringing about definite increase of accidents; all of the above mentioned bad conditions in ""blind ends"" in metal mines as well as their ill effects, are remediable by providing at those places adequate quantities of fresh circulating air."

Nov 1, 1923

By G. W. Jones

[The determination of the ignition tcqornturc ol" dict:iyl cther and othylene in air ma o;GrT;en rir..ic'r. is dcscribed In thin report J'IF.R mqdo primarily for comparison rritll sinilnr d~ton:in:~tions of ot; cr co~~o~imS-r, in the same apparatus and using the r?.:?.r.~o 1a.borntorg t cchzllique The investigation was conducted at the 2ittsbur;;h Experiment Station of the United States wcau 02 hii2cs vritEl tl~c cooperation of licrclc & Co., Inc.]

Jan 1, 1935

By B. J. Dalton

The Helium Research Center, Helium Activity, Bureau of Mines, is presently engaged in a critical examination of all of the PVT data on helium that appear in the literature. The long-range objective is the development of a single equation of state for helium that will allow all of the thermodynamic properties to be calculated and will reproduce all of the data within the accuracy with which the data arc known. A preliminary objective is to obtain the best val¬ues of the second virial coefficients and to develop an equation that will reproduce the best values as a function of temperature. The method of treatment consists in expressing the PV product of a gas, for a given isotherm, in terms of a power series in either the pressure or the density and evaluating the constants by least squares solution. Associated with these functions whose coefficients have been evaluated by least squares, the following errors, or deviations, are of interest; the standard error of a single measurement; the standard error in each coefficient; and the standard error of the resulting function.

Jan 1, 1964

By B. J. Dalton

The Helium Research Center, Helium Activity, Bureau of Mines, is presently engaged in a critical examination of all of the PVT data on helium that appear in the literature. The long-range objective is the development of a single equation of state for helium that will allow all of the thermodynamic properties to be calculated and will reproduce all of the data within the accuracy with which the data are known. A preliminary objective is to obtain the best values of the second virial coefficients and to develop an equation that will reproduce the best values as a function of temperature. The method of treatment consists in expressing the PV product of a gas, for a given isotherm, in terms of a power series in either the pressure or the density and evaluating the constants by least squares solution. Associated with these functions whose coefficients have been evaluated by least squares, the following errors, or deviations, are of interest; the standard error of a single measurement; the standard error in each coefficient; and the standard error of the resulting function.

Jan 1, 1964

By William Hustrulid

The National Institute for Occupational Safety and Health (NIOSH), as part of a comprehensive program to improve mine safety through the widespread acceptance of careful excavation principles in drifting, have revisited standard drift round design concepts. Although the initial emphasis was on contour row design and providing improved design tools for blasting with de-coupled charges, the focus has broadened into the development of a general gas pressure-based drift round design approach. The concept of a damage radius (Rd) for a given explosive-hole-rock mass combination is introduced. With the damage radius as the basic building block, the blast holes are positioned on the face, beginning with the buffer row, to achieve the desired excavation size, shape and smoothness. The design of the contour row of holes is also performed using a pressure-based approach. The paper presents in some detail the overall approach and the required gas pressure-based design equations.

Jan 1, 2007

By John R. Bartels

This report discusses an improved method for rerailing underground railcars devised in a joint effort by the Bureau of Mines and Hoesch MFD. This improved method utilizes a lightweight hydraulic ram with hand-pump activation to move a bridge-mounted roller carriage in conjunction with steel-reinforced air-lift bags. This method provides a lightweight portable system in which only two workers are required to perform the mine car rerailing operation. Because of the very narrow confines in underground mines, use of overhead cranes and other surface rail techniques is not possible. This new system is designed for very low profile work, and provides the necessary lifting force from light- weight compressed-air bottles.

Jan 1, 1985

By Harry W. Campbell

In 1986 at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 2 acre North Sisters Rocks Wilderness Study Area (OR-12-8) in order to evaluate its identified mineral resources. The Wilderness Study Area is located in Curry County, Oregon, about 15 miles north from Gold Beach. No mines, prospects, or mining claims were located inside the study area, and no mineral resources were identified. Stone from the study area could be quarried and used for construction purposes; however, two nearby quarries have sufficient stone to satisfy local construction needs. INTRODUCTION This report describes the USBM (U.S. Bureau of Mines) portion of a cooperative study with the USGS (U.S. Geological Survey) to evaluate mineral resources and mineral resource potential of the North Sisters Rocks WSA (Wilderness Study Area) 1/ at the request of the BLM (U.S. Bureau of Land Management). The USBM examines individual mines, prospects, claims, and mineralized zones, and evaluates identified mineral and energy resources. The USGS evaluates potential for undiscovered resources based on areal geological, geochemical, and geophysical surveys. Results of investigations will be used to help determine the suitability of the North Sisters Rocks WSA for inclusion into the National Wilderness Preservation System. Although the immediate goal of this and other USBM mineral surveys is to provide data for the President, Congress, government agencies, and the public for land-use decisions, the long-term objective is to ensure the Nation has an adequate and dependable supply of minerals at a reasonable cost.

Jan 1, 1987

By Michael J. Friedel

As part of an investigation aimed at improving the health and safety and competitiveness of the mining industry, the U.S. Bureau of Mines evaluated the application of common offset radar profiling, using a 250-MHz ground-penetrating radar (GPR) system, for the detection of fractures in igneous rock. A series of radar reflection surveys were conducted to detect and delineate the extent of fracturing at various granodiorite and gabbro quarries and outcrops located in Minnesota. The application of radar profiling for detecting joints, sheeting fractures, shear zones, and depth to water table was demonstrated to be feasible with minimal processing. Radar reflection interpretations were verified by visual inspection of the rock mass and field mapping of local structure. The radar reflection section provides a simple, rapid, and cost-effective means for mapping of shallow (less than 10 m) small-scale fractures (greater than 0.25 cm) in igneous rock masses (characteristic of velocities between 0.061 m/ns for gabbro and 0.125 m/ns for granodiorite). Depth or distance estimates to fractures are within 10 pct of the actual, and time-shift compensation is necessary only when topographic irregularities exceed 30 cm.

Jan 1, 2010

By L. E. Dalverny

This Bureau of Mines report describes the deployment, 5-month operation, and lessons gained from a continuous gas monitoring system using sampling-tube bundles at an underground mine fire in West Virginia. Research information gained indicates the utility of relating certain gas concentration ratios to events during fire development, mine reventilation, and mine recovery. In addition to monitoring the quality of remote fly ash seals, the system provided timely warning of dangerous gas concentrations which developed during surface and underground recovery activities. An evaluation of system components is supplemented by recommendations for improvements.

Jan 1, 1975