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By William O. Vanderburg

This paper describing the methods and costs of milling scheelite ore at the Silver Dike concentrator of the Nevada-Massachusetts Co., Inc., is one of a series being prepared by the Bureau of Mines. In the Silver Dike mill tungsten ore which contains about 1 per cent of scheelite is treated at the maximum rate of 45 tens per 24 hours by tabling followed by magnetic separators to clean the table concentrates. Unusually high-grade concentrates are produced which average between 70 and 75 per cent of W03.

Jan 1, 1932

By J. B. Littlefield

The Greenburg-Smith impinger was developed at the Bureau of Mines in cooperation with the United States Public Health Service in 1922 in the course of an investigation of dust-sampling instruments available at that time. Although it is not used extensively outside of the United States, it is now soused in this country to collect samples for the determination of any dustiness, and most of the information correlating degree of dustiness with physiological effect has been obtained by the impinger method. The chief disadvantages in the use of the regular impinger, especially in mines and other places accessible with difficulty, are its bulk, weight, and power requirements. It requires a source either of electricity or of compressed air, which necessitates connections and extension of existing supply lines to each sampling point; the only alternative is the use of a relatively large pump hand-operated with considerable effort.

Jan 1, 1937

By T. M. Ruff

The U.S. Bureau of Mines has developed a portable, inexpensive teleoperation system for mobile hard-rock mining equipment. The system was tested on a compact loader-trammer in a simulated stope. The teleoperation system includes radio remote control and computer-assisted navigation. A recent enhancement includes video cameras mounted on the machine to provide visual information to the operator. This system allows the operator to remain in a safe location while operating the machine from a distance, thus increasing both operator safety and mining productivity.

Jan 1, 2010

By James P. Rider, Jeanne A. Zimmer, Andrew B. Cecala, Robert J. Timko, Earle H. Andrews

Many different types of structures and materials have been used to build mineral processing facilities over the past few decades. Although the structure type and building material were not viewed as significant factors affecting the health of employees in these facilities when they were built, the National Institute for Occupational Safety and Health performed an evaluation to determine to what extent building types could impact respirable dust and noise levels. This report discusses the evaluation of three different types of product sizing silica sand structures: a masonry design, a steel-sided design, and an open structure design. The data obtained in this study indicate that the open structure design (no walls) was superior from both a dust and noise (health) standpoint compared to the other two structures. The open structure design should also be beneficial from a cost standpoint because of lower material and construction costs. Companies and design engineers should consider this open design when building new mineral processing facilities in climates where it could be applicable. Some companies may also want to consider modifying existing structures with a more open design to further reduce dust and noise levels. As the trend continues in lowering allowable dust levels for federal health standards in the U.S. mining industry, the open structure design may be an approach for some companies to consider for their operations.

Jan 11, 2006

By D. G. Kuehn

Mass spectrographic studies have been conducted on the positive ions and neutral species of glow discharges containing 1.0 pct S02 and 1.0 pct CO in helium. Measurements were conducted for gas pressures from 3.5 to 10.1 torr using both dc and 60-Hz ac excitation. The ion species that were observed included S+, SO+, SO+, 0+, O2+, C+, CO+, and CO2+ with lesser amounts of SO3+, (CO)2+, SCO+, and (SO?CO)+ or CS+2. Interpretation of the functional dependence of the various ionic and neutral species on pressure and applied power showed that CO reacted with the SO formed in the discharges to produce CO2 and sulfur. Deposition of elemental sulfur was observed in the plasma container.

Jan 1, 1973

By R. H. Thompson

Six different types of blasting caps, mainly of the type used in coal mines, were evaluated to determine both their 1lF and DC characteristics. Two of the caps were of foreign manufacture. All the American made caps had "no-fire" (0.1% firing probability with 95% confidence, as determined by the Bruceton test) levels above 0.04 watts. One of the caps of foreign manufacture had a "no-fire" level of 0.023 watts. A worst case analysis of blasting cap pick up of RF power in coal mines was performed and safe distance curves were generated.

Jan 8, 1973

By Jr. Herty

Ferromanganese continues to be an indispensable requirement in steel manufacture. Approximately 470,000 of the 80 per cent ferro-alloy was consumed in 1929 and increasing amounts will be required annually by the steel industry unless some satisfactory substitute is found. An average of 14 pounds of metallic manganese is used for each ton of steel produced, The principal use of manganese is for de-oxidation of the metal in the steel refining processes, although a considerable amount is also used for the production of special manganese steels. Unfortunately, domestic production of manganese ore is inadequate to meet normal peace-time requirements, not to mention increased abnormal war-time demands. The rather large quantities of low-grade manganiferous iron ores which occur in the Coruna Range in Minnesota have for a number of years greatly appealed to those interested in the development of a domestic source of the supply. The North Central Experiment station of the Bureau of Mines has made an elaborate study of the possibilities of the pyrometallurgical treatment of ores from these deposits and much of the valuable information secured by them has already been published.

Jan 1, 1930

1. Data from the Mine Safety and Health Administration (MSHA) indicate that a total of 241,502 employees worked in surface mining locations in 2003, corresponding to 212,113 full-time equivalent (FTE) workers. • Surface employees accounted for 84.6% of all mining employees. • The majority of surface employees (73.7%; n = 177,927) were mine operator employees as opposed to contractor employees. • Stone operator employees comprised the greatest percentage (27.2%; n = 65,743) of surface employees.

Feb 1, 2005

By G. S. Rice, R. V. Wheeler

"FOREWORDThe cooperative mine safety research program was carried on successfully in the year 1930 in a manner similar to that described in the report for 1929It is believed that the results of such fundamental work as is being done are unquestionably of great benefit in their application in coal-mining operations, in the saving of life and health of minera. The research result compared and checked by investigations in the two organizations, and further by large-scale tests, as in the Experimental Mine, give confidence to mine operators, miners and State mining officials in the findings of the various researches.The annual report of the contact officers of the United. States Bureau of Mines and the British Safety in Mines Research Board to the Director of the Bureau and the Chairman of the Board respectively, follows:Annual Reports for 1930 To: The Director, Bureau of Mines.The Chairman, Safety in Mines Research Board."

Sep 1, 1931

By Louis A. Turnbull, JOSEPH J. SHIELDS

The Bell & Zoller Coal & Mining Co. recently completed construction of two slopes at Mine 3 near Zeigler , Ill . The slopes are in the Big Muddy River Valley , and construction was particularly difficult because the strata from the surface to a depth of 70 feet comprise water saturated sandy clay and sand . Many mining companies have similar shaft- and slope - sinking problems , and because these slopes were satisfactorily completed and now are in use the methods followed during construction are described in this information circular . It is believed that other companies with similar problems . will benefit by adopting the methods followed at Mine 3 .

Apr 1, 1949

By T. R. Taubert, D. H. Carlson, J. H. Johnson

The U.S. Bureau of Mines and Michigan Technological University (MTU) are collaborating to develop an apparatus for measuring diesel tailpipe emissions in underground mines. A tailpipe emissions measurement apparatus (EMA) is described that dilutes diesel exhaust and measures the concentrations of diesel particulate matter (DPM), CO, CO, NO, and NO, at known dilution ratios. The EMA was evaluated by side-by-side comparison of its measurements with those by laboratory- grade instruments. Concentrations of CO and CO, measured by the EMA were usually within + 14 pct of concentrations measured by laboratory-grade instruments for CO and 220 pct for CO,. EMA- measured DPM concentrations were, on average, 29 pct lower than those measured by laboratory-grade instruments, with the differences being fairly consistent. The CO and CO, differences are related to the method of calculating the EMA's dilution ratio, and the difference in DPM concentrations is attributed to thermophoretic and/or condensation losses related to the EMA's unheated sample probe. Preliminary analysis of data obtained with a heated sampling probe and modifications in the sampling procedures have indicated reduced variability in DPM and in the calculated dilution ratios.

Jan 1, 1992

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

Improve the reliability and accuracy of subsurface images using constrained tomography with enhanced ray-tracing capabilities. Background Geophysical tomography is a technique for imaging the structure of a rock mass using seismic or radio waves, in the same way that medical CAT scans image human tissue using X-rays. Tomography has found numerous practical applications related to mining, including lithologic and structural characterization, fracture detection and fluid monitoring, void detection, and evaluation of stress state and integrity of mine structures. Problems Two fundamental problems have largely prevented geophysical tomography from enjoying the tremendous success achieved by medical tomography. The first is a consequence of practical limitations on the placement of sources and receivers of wave energy: ideal resolution can be attained only when the region being imaged is entirely surrounded by sources and receivers, so that it is crossed by rays traveling in all possible directions. When such coverage is impossible or impractical, the inversion becomes underdetermined: there id not enough information in the measured data to provide a mathematically unique solution. The second major problem in geophysical tomography is the necessity for detailed ray tracing. Commercial software, as well as previous U.S. Bureau of Mines (USBM) software, employs a ray-shooting algorithm that may be unable to model some ray paths when velocity contrasts are larger than about 100%. These ?shadow zones" result in loss of data and degradation of reconstructed images.

Jan 1, 1994

By McHenry Mosier

A skull breaker has demonstrated its advantages for secondary breaking in a limestone quarry by entirely displacing secondary blasting . It has reduced safety hazards to workmen, increased the number of quarry operating days , and has lowered mining costs by 2.7 cents a ton. It is believed that the application of the skull breaker can be made economically advantageous in the surface mining of other commoditics .

Aug 1, 1948

By D. F. Scott

The purpose of this study was to determine if miners were at risk from exposures to chemicals used in the mining industry and determine the nature and sources of the illnesses and injuries. The U.S. Mine Safety and Health Administration?s (MSHA) employment and accident, injury and illness database was reviewed. There were 2,705 cases of chemical-related injuries and illnesses reported from 1999 through 2006, involving 66 different chemicals. The main source (cause) of chemical-related cases was acids/alkalis (about 39%). The primary nature (effect) of chemical-related cases was chemical burns (about 57%). The job classification where workers incurred the most chemical-related injuries and illnesses was cleaning plant operator/media operator/boney preparation plant operator/crusher worker (cleaning plant operators are responsible for maintenance of plants, media operators are responsible for handling reagents, boney preparation plant operators oversee removal of ?bone? from coal, and crusher workers use large crushers to break mined material). From 1999 through 2006, the rate of ?nonfatal days lost? and ?no days lost? (resulting from injuries) did not change significantly; however, the rate of illnesses decreased significantly. Chemical burns accounted for a large number of injuries; mining companies should carefully examine their personal protective equipment (PPE) requirements, training methods and safety culture to ensure that their workers are protected.

Jan 1, 2009

By R. R. Sayers, W. J. McConnell

"The health, comfort, and efficiency of men engaged in the mining industry may be impaired, in some instances very seriously, by abnormal physical conditions of the mine air or by variations in its composition. This is true in some of sheet metal mines of the West where high temperatures with varying humidities are encountered. Physiological studies have been made in some of these mines showing the effects of various temperatures end humidities. As it is difficult to carry out studies on many controlled temperatures, it was thought best to make the experiments in a laboratory and apply the results to the industry insofar as practicableThe effects of moderately high temperatures and humidities are more difficult to measure perhaps than the extreme conditions, but may be predisposing causes of fatigue, discomfort and disease, A cooperative study of the physioloical effects of heat and humidity is being conducted by the Bureau of Mines and the U. S. Public Health Service cooperative with the American Society of Heating and Ventilating Engineers, in the Research Laboratory of the Bureau of Mines at Pittsburgh, Pa."

Mar 1, 1924

By J. E. Zeilinger

This Bureau of Mines study was conducted to determine the sulfur reduction potential attainable when washing fine-size coal on a spiral concentrator. Crushed samples of Middle Kittanning and Bakerstown bed coals washed on the spiral provided pyritic sulfur reductions of up to 90 percent for the plus 200-mesh material. Pyritic sulfur reductions on the minus 200-mesh material seldom exceeded 30 percent; consequently, this material would require further treatment. The capacity of the spiral was 2 tph per unit when washing l4-mesh by 0 coal. The ability to remove pyrite combined with the higher-than-expected capacity makes the spiral worthy of consideration as a rougher-cleaner in new fine-coal desulfurization circuits.

Jan 1, 1976

By K. C. Dean

Time and motion studies were made by the Federal Bureau of Mines on the hand and machine dismantling of scrapped auto starter motors, generators, and alternators for recovery of copper, aluminum, and iron. The studies showed that an individual with power handtools and convenient access to a hydraulic press, power bandsaw, acetylene torch, and power lathe could, in an 8-hour day, disassemble about 100 starters, or 150 generators, or 30 alternators. The scrap copper yield would be 280, 390, and 45 pounds, respectively, and the iron yield would be about seven times the copper weight. About 100 pounds of aluminum would be obtained from the alternators.

Jan 1, 1976

By M. H. Rinkenbach, C. A. Taylor

The detonating compound cyanuric triazide was discovered*** and patented**** by Erwin Ott, and on account of his claims, the Bureau of Ordnance, U. S. Navy, desired more complete data, so an investigation was made. The results obtained were such that the Bureau of Crdnance recommended publication thereof for the benefit of the explosives industry. Some of the patent claims regarding cyanuric triazide are as follows: 1. It is not poisonous in contradistinction to fulminating mercury and lead azide. 2. In contradistinction to the hitherto employed priming agents it is fusible, and its fusion point (94°C) is so low that the product melted by a single heating in water or steam bath, can be poured without danger in the capsule shell. It solidifies therein after cooling, and shows the density of 1.5. 3. It has been determined that the cyanuric triazide, in spite of its very much higher priming actions, is much less brisent then ful- minating mercury and lead nitride. 4. The chemically pure cyanuric triazide (C3M2) constitutes colorless crystals melting at 94°0., and is not volatile. It is not affected by cold water, and only slowly saponified by hot water. It is relatively insensitive to friction and not too strong concussion, but explodes by impact or when hea ted to 170°C., or when heated suddenly. It is not more sensitive to friction and shocks then fulminating mercury. 5. The preparation of the triazide is preferably carried out by acting with an excess of sodium azide in an aqueous solution; in the cold, on cyamric chloride gradually suspended in the said solution.

Aug 1, 1923

By Wesley A. Grosh

The Vest nickel prospect, in Floyd County, Va., was discovered about 25 years ago. Limited exploration of the deposit had indicated some appreciable nickel mineralization in the sulfide ore. The property was examined on March 9, 1943, by an engineer of the Bureau of Mines in company with C. W. Vest, owner of the property. A limited exploration program was recommended. Two holes totaling 320 feet were diamond-drilled in January 1944. Drilling indicated the sulfides are sparsely disseminated. The only nickel values of interest were at the old prospect shaft.

Jan 1, 1949