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By Robert A. Jankowski

The U.S. Bureau of Mines, in cooperation with the Mine Safety and Health Administration (MSHA) and the mining industry, has identified and demonstrated the effectiveness of several improved face ventilation techniques for longwall mining systems. These include the following: identifying improved techniques for measuring face ventilation parameters on longwall sections, installing curtains at the intake end of the longwall face to maximize usage of the primary airflow, identifying optimum face airflow rates for maximizing dilution effects, and coursing the primary face intake from tailgate to headgate to minimize outby airflow contamination. Application of these techniques throughout the mining industry should reduce the health hazard associated with excessive exposure to respirable coal mine dust.

Jan 1, 1993

By W. I. Nelson

This paper which describes the milling practice of the Engels Copper Mining Co., is one of a series on milling methods being prepared for and published by the United States Bureau of Mines. ACKNOWLEDGMENTS Acknowledgment is made of the assistance rendered by J. Casagrande, mill foreman of the Engels concentrator, in collecting much of the data presented in this paper.

Jan 1, 1932

From time to time the Bureau of Mines has interpreted and applied certain provisions of the Federal Coal Mine Safety Act and Federal Mine Safety Codes, primarily for the guidance of Federal Coal Mine Inspectors. Although interpretations of the Act have appeared in the Federal Register, the Code interpretations and practical applications have not been published. In response to many requests from representatives of the coal-mining industry, the Bureau is publishing this information to promote better understanding of those provisions that may be misinterpreted or misapplied. INTERPRETATIONS AND APPLICATIONS Two Federal Mine Safety Codes are discussed in this report, namely the Federal Mine Safety Code for Bituminous-Coal and Lignite Mines of the United States, Part 1, and the Federal Mine Safety Code, Anthracite Mines of the United States, Part 1. In this circular the word Codes refers to both directives; Code* refers to the code for bituminous-coal and lignite mines; Code? refers to the one for anthracite mines. Act* refers only to bituminous-coal and lignite mines.

Jan 1, 1963

By Larry D. Nichols

Poroplastic membranes containing ion exchange liquids were studied for separating cobalt from nickel-containing solutions similar to ammoniacal laterite leaches. The driving force for cobalt transport was differences in pH and composition between the leach and extraction streams. Using a diketone ion exchange liquid, a leach pH of 6.5 to 7.0, and a strip pH of 2.3, cobalt was extracted from a 750 ppm solution containing 2500 ppm of nickel at rates ranging from 1 to 10 µg/cm2 .min in single membrane cells, and from 10 to 100 in more closely spaced multiple membrane cells. Rates were variable, with evidence that cross -membrane flow pasterns were a key factor; a reproducible rate of 30 pg/cm .min would be economically viable. Loss of transport observed after several days of continuous operation was restored by flushing membranes with fresh ion exchange liquid. A major effort was devoted to preparation of thin, leak-free membranes; the resulting membranes endured operating conditions without mechanical failure.

Jan 1, 1982

By G. R. Strimbeck

This is a report on experimental work on development of a gasification process operating at near atmospheric pressures and using finely pulverized coal entrained in oxygen and steam. The gasifier was designed by The Babcock and Wilcox Co. in cooperation with engineers of the Bureau of Mines Morgantown station. The test work discussed in this report covers the first 34 tests made in the pilot plant in which a strongly coking Sewickley-bed coal, ground to either 70 or 90 percent through a 200-mesh screen, was used.

Jan 1, 1954

By V. A. Nieberlein

This paper presents the results of research undertaken to recover titanium and columbium by low-temperature chlorination of low-grade columbium-bearing ilmenite concentrates, and to simultaneously remove chlorinated impurities from the volatile chlorides without resort to distillation. Coke-reduced ilmenite was chlorinated at 400° to 500° C., and the resulting TiC14 was free of most impurities before condensation. A heated purification column was used wherein various packing materials reacted chemically or physically with the impurities which passed through them in the vapor phase. A nearly water-white TiC14 product was obtained directly. The principal impurities in the titanium tetrachloride were: 0.02 percent Fe, 0.01 percent V, 0.05 percent A1, 0.04 percent Si, and 0.07 percent Cb. This is a less pure product than commercial TiC14. Most of the columbium was recovered as crude CbC15, requiring further refining.

Jan 1, 1960

By Edward D. Thimons

The Bureau of Mines has developed a damage-resistant brattice, intended for use as a stopping in locations where blast damage to stoppings is a problem, the roof is relatively flat, and the differential pressure across the stopping is not high. Damage-resistant brattices consist of a series of vertically hung brattice panels joined to each other by Velcro connections that improve the airtightness of the brattice. When the brattice is subjected to strong blast forces, the Velcro connections peel apart, allowing the panels to open without incurring damage. The Velcro connections can then be resealed in a matter of minutes. A preliminary test in the Bureau's Safety Research Mine and subsequent long-term testing at the White Pine copper mine in Michigan and the Retsof salt mine in New York show that damage-resistant brattices withstand blasting better than conventional stoppings, while still performing as efficient air barriers when the Velcro connections are sealed.

Jan 1, 1978

By Donald W. Mitchell, John Nagy

Observations made on coking of coal, deposition of soot, dust transport, flame, violence, and related phenomena following experimental coal-dust explosions are summarized. Data are given on gas explosion pressure, flame length, flame velocity, and variation of these parameters with concentration. Conclusions from these observations are useful in preventing similar occurrences in operating mines and serve as a guide in improving safety.

Dec 1, 1963

By S. H. Ash

As part of the work done at the Washington coal mines during the year 1929 , a study was made of the safety practices in and about the mines . Inasmuch as electrical blasting has made considerable headway it is interesting to note the manner in which it is done and the reasons why it was discarded at some of the mines . Blasting is done at the mines in the State by means of capped fuse , electric blasting " caps , " and in some instances by electric delay detonators . Black blasting powder with fuse is used at most of the open- light mines . The use of squibs was discontinued several years ago because the coal operators , without exception , recognized the dangers incidental to their use . Permissible explosive and dynamite are also used at some of the open- light mines . With the exception of some rock work and the driving of level work in gangways and air courses the explosive is detonated by means of capped fuse .

Apr 1, 1930

By N. S. Dalal, X. Shi

It has been known for more than a decade that vanadium (V) stimulates the oxidation of NADH by plasma membranes (1) but the underlying mechanism is still not fully understood. This effect has been attributed to a membrane-associated NADH-dependent vanadium (V) oxidoreductase (1). Subsequent studies suggest that vanadium ( V) can accept an electron from fiavoprotein dehydrogenase that oxidizes NADH (2). The phenomenon ofNAD(P)H oxidation coupled to vanadium(V) reduction has also been demonstrated in other biological systems (3-6). A recent electron spin resonance (ESR) study from our laboratory reported on the accumulation of vanadium (IV) duringthe reduction ofvanadate (vanadium(V)) by the ftavoenzymes glutathione reductase (GSSG-R),4 lipoyl dehydrogenase, and ferredoxin-NADP+ oxidoreductase in the presence of NAD(P)H (7). It was concluded therein (7) that these ftavoenzymes function as NAD(P)H-dependent vanadium(V) reductases. More recently, however, Liochev and Fridovich (8) have argued that the ESR data (7) do not demonstrate that the investigated fiavoenzymes act as vanadate reductases. They suggest an alternative mechanism in which the fiavoenzyme simply serves as a generator ofsuperoxide (02) radical, which acts as a propagator of the radical chain reaction leading to NAD(P)H oxidation (9, 10), as summarized below:

Nov 1, 1995

By N. B. Greninger

The U.S. Bureau of Mines conducted explosion tests on various full-scale cementitious bulkheads used in abandoned mine areas to evaluate the ability of the bulkheads to withstand gas explosion over-pressures of 20 psig. Tests were performed on 120-ft2 solid-concrete-block seals of varying thicknesses and designs. Of the seven solid-concrete-block seals tested, only the standard-type seal, having a 16-in thickness, keyed at the floor and ribs, all joints mortared, wedged at the roof, and a center pilaster, maintained its integrity when subjected to a 20-psig pressure wave. After being subjected to repeated explosions, the standard seal only showed a small hairline crack and had an air leakage of 87 ft3/min at a pressure differential of 1 in H2O. Tests were performed on cementitious foam seals of varying thicknesses and compressive strengths. Explosion tests have shown that 200-psi strength, 4-and 8-ft-thick seals can withstand a 20-psig pressure wave. At a pressure differential of 1 in H20, no air leakage was detected through the 200-psi, 8-ft-thick foam seal.

Jan 1, 2010

By W. G. Pariseau

A U.S. Bureau of Mines case study of pillar recovery in high-grade ore near the Ross shaft at the Homestake Mine, Lead, SD, has demonstrated the usefulness of the finite-element method for evaluating shaft pillar mining plans and shaft stability. This report focuses on mine measurements and calibration of the two-dimensional computer model and is the second in a series of three Reports of Investigations describing the Ross shaft study. In this study, borehole extensometers and other instruments were installed to provide data for model verification and to monitor the shaft. Results of the recalibrated two-dimensional model (UTAH2) confirmed the premining stability evaluation. However, after mining began, concern was expressed because cracks and other signs of ground motion appeared at considerable distances from the area of active pillar mining. In part 3 of the study, an intensive three-dimensional modeling effort using UTAH3 was initiated. The results again showed that the observed effects were within expectations and that the shaft would remain safe. Three-dimensional analyses of alternative pillar mining scenarios indicated that more of the shaft pillar ore reserve could be recovered than previously thought.

Jan 1, 2010

In 2006, 14,885 mining operations reported employment data to the Mine Safety and Health Administration (MSHA).1 Almost half (48.2%) were sand and gravel mines, followed by stone mines (30.7%), coal mines (14.2%), nonmetal mines (5.0%), and metal mines (1.9%).

Jan 1, 2008

In 2006, data obtained from the Mine Safety and Health Administration (MSHA) indicated a total of 935 underground (6.3%) and 13,950 surface (93.7%) mining operations.1

Jan 1, 2008

In 2006, a total of 280 metal mining operations reported employment to the Mine Safety and Health Administration (MSHA).1 Metal mines were the smallest mining commodity sector, comprising 1.9% of all mining operations. ? Gold mines comprised 46.8% (n=131) of all metal mining operations. Other common types of metal mines were copper ore (n=34; 12.1%), and iron ore (n=33; 11.8%). Nevada had the largest number of metal mines (n=53; 18.9%), followed by Alaska (n=31; 11.1%).

Sep 1, 2008

In 2006, a total of 280 metal mining operations reported employment to the Mine Safety and Health Administration (MSHA).1 Metal mines were the smallest mining commodity sector, comprising 1.9% of all mining operations. ? Gold mines comprised 46.8% (n=131) of all metal mining operations. Other common types of metal mines were copper ore (n=34; 12.1%), and iron ore (n=33; 11.8%). ? Nevada had the largest number of metal mines (n=53; 18.9%), followed by Alaska (n=31; 11.1%).

Jan 1, 2008

The Mine Safety and Health Administration (MSHA) defines an independent contractor as any person, partnership, corporation, subsidiary of a corporation, firm, association or other organization that contracts to perform services or construction at a mine. Contractors that perform specific types of work are required to report the number of employees who work at coal mines and noncoal mines.

Jan 1, 2008

In 2006, a total of 2,113 coal mining operations reported employment to the Mine Safety and Health Administration (MSHA).1 Coal mines comprised 14.2% of all mining operations. ? Bituminous mines comprised 92.5% (n=1,955) and anthracite mines 7.5% (n=158) of coal mining operations. ? Approximately 71.0% of all coal mines were located in three states: Kentucky (29.2%), West Virginia (21.8%), and Pennsylvania (20.3%).

Jan 1, 2008

The Mine Safety and Health Administration (MSHA) defines an independent contractor as any person, partnership, corporation, subsidiary of a corporation, firm, association or other organization that contracts to perform services or construction at a mine. Contractors that perform specific types of work are required to report the number of employees who work at coal mines and noncoal mines.

Jan 1, 2008

In 2006, a total of 7,178 sand and gravel mining operations reported employment to the Mine Safety and Health Administration (MSHA).1 ? Sand and gravel mines were the largest mining sector, comprising 48.2% of all mining operations. ? Sand and gravel mines were found throughout all 50 states and Puerto Rico.

Sep 1, 2008