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By Joseph E. Chilton, Robert J. Timko, Charles D. Taylor

No regular monitoring of methane is required in areas of gassy coal mines outby the mining face. Methane ignitions that have occurred in mine outby areas indicate the need to provide better protection to workers. Handheld methane monitors are now used by some miners to make periodic measurements of methane at the working face. The IYONI II gas detector which is incorporated into a miner’s cap lamp and worn on a miner’s helmet can continuously provide an alarm signal whenever methane levels exceed a set level. Tests were conducted to evaluate the performance characteristics of this methane detector by measuring response times with methane gas supplied through a calibration fixture or adaptor. Other response time tests were performed with the detector in an environmental test box. Performance was also evaluated in a full scale test gallery where face methane emission and underground ventilation were simulated. Procedures for calibration by response time measurement of the IYONI II detector have been developed. In limited testing, the IYONI II detector was found to reliably detect the presence of 1 percent by volume methane.

By D. E. Traut

The effect of various ion concentrations on uranium absorption from a sodium carbonate solution by a strong-base, anion resin was investigated by the Bureau of Mines in support of its objective to help assure an adequate uranium supply for future needs. The studies were conducted to improve the recovery of uranium from in situ leach solutions by ion exchange. The effects of carbonate, bicarbonate, chloride, and sulfate ions were examined. Relatively low (less than 5 g/l) concentrations of chloride, sulfate, and bicarbonate were found to be detrimental to the absorption of uranium. High (greater than 10 g/l) carbonate concentrations also adversely affected the uranium absorption. In addition, the effect of initial resin form was investigated in tests of the chloride, carbonate, and bicarbonate forms; resin form was shown to have no effect on the absorption of uranium.

Jan 1, 1979

By P. R. Bremner

In keeping with its mission to maximize mineral and metal recovery from domestic sources, the Bureau of Mines investigated a method to extract silver from tailings not amenable to cyanidation. Results of a laboratory study on the recovery of silver from cyanide tailings containing 1.7 ounces of silver per ton by leaching with an acidic ferrous chloride-sodium chloride solution are presented. The effects of reagent concentration and reaction time on the leaching of silver were investigated. A leaching solution containing 5 wt-pct NaCI, 2.5 wt-pct FeCI2, and 1.2 wt-pct HCI (for acidity) extracted 82 pct of the silver from the tailings during a 24-hour leach. The amount of HCI consumed during the leach was 46 pounds of HCI per ton of feed. Only 23 pct of the silver was extracted by conventional cyanidation. Ninety-nine percent of the silver was recovered from the pregnant solution by cementation onto iron powder.

Jan 1, 1982

Develop a simple and practical technique to measure in situ rock mass properties for realistic design and stability evaluation of underground structures. Background The Bureau of Mines has developed basic principles and techniques to determine in situ rock mass properties including Poisson's ratio, deformation modulus, and yield and failure strengths. An instrumentation package consisting of three pressure cells is installed in a single drill hole. Cell pressure response data are acquired and used to calculate and determine the rock mass properties. How It Works A test hole of BX size (approximately 5.7 cm) or larger is drilled to the approximate depth of the measuring point. The last portion of the test hole is drilled with precision bits to EX size (approximately 3.8 cm). The instrumentation package, which consists of one 3.8-cm-diameter cylindrical pressure cell (CPC) and two 5.7-cm-diameter cement-capsulated, flat borehole pressure cells (BPC's), is then installed. A complete history of cell response to changing strata loads is acquired on a continuous basis with a chart-type hydraulic pressure recorder. From these cell pressure data, Poisson's ratios, deformation moduli, and yield and failure strengths are calculated and determined.

Jan 1, 1990

Develop a cost-effective diesel aerosol sampler that can be used by industry and regulatory agencies to determine the diesel exhaust aerosol concentration in mine atmospheres. The sampler must be easy to use, wearable by mine personnel, compatible with current personal sampling protocols, and inexpensive. Approach The University of Minnesota (University) and the U.S. Bureau of Mines (USBM) have developed and tested a prototype diesel exhaust aerosol sampler. The sampler, however, was complicated and expensive to fabricate. Consequently, the USBM redesigned the sampler to simplify both manufacturing and use, and the sampler was evaluated to ensure equivalency with the prototype. Background The National Institute for Occupational Safety and Health (NIOSH) has recommended that "whole diesel exhaust be regarded as a 'potential occupational carcinogen,' as defined in the Cancer Policy of the Occupational Safety and Health Administration." In addition, the U.S. Mina Safety and Health Administration (MSHA) has been directed by an advisory committee to establish a diesel exhaust aerosol standard and regulations to minimize exposure to diesel pollutants in underground coal mines.

Jan 1, 1992

By A. N. Styler

As part of its water-jet assisted rock cutting research, the Bureau of Mines has initiated a study into the mechanism of rock fragmentation by water-jet-assisted mechanical tools. The objective of this research is to increase coal extraction efficiency by seeking an improved understanding of the synergistic relationship between mechanical cutters and water jets, enabling the design of more effective cutterheads. Rock chips collected during laboratory traverse speed jet-assisted cutting tests were analyzed with respect to the size distribution of the chips and the forces measured during cutting. As the water-jet pressure was increased, the size distribution of the product became coarser with V-face type cutting tools producing less fine material than conical cutting tools. Fracture mechanics theory accounted for less than 10 pet of the energy consumed during fragmentation of the rock. The energy consumed by processes other than rock breakage decreased with the use of water jets and increasing advance rate.

Jan 1, 1987

By A. R. Rule

Laboratory tests were conducted to study removal of magnesium impurities from western phosphate rock concentrates by selective leaching. The systems evaluated included leaching with dilute sulfuric acid, with ammonium sulfate, and in an aqueous medium with sulfur dioxide gas. Set standards for the magnesium impurity level of phosphate rock concentrates are not available, but industrial practice has indicated that magnesium in excess of 0.3 percent MgO causes problems in phosphoric acid manufacture. Removal of magnesium was accomplished with all three systems. With dilute H2S04 the magnesium level was reduced to less than 0.1 percent MgO with an accompanying P205 loss of 6 percent. Magnesium oxide levels from 0.3 to 0.2 percent were obtainable with ammonium sulfate. However, the system requires concentrate roasting at temperatures of 900° C or higher, heated pulps (100° C), and large quantities of ammonium sulfate. Selective leaching was obtained using S02 gas in an aqueous concentrate slurry. Magnesium oxide content was reduced to less than 0.1 percent without loss of phosphate.

Jan 1, 1970

By P. G. Barnard

Losses of alloying metals in furnace flue dusts, grinding swarfs, and mill scale produced during the manufacture of stainless steel are substantial. About 25 million lb Cr, 8.7 million lb Ni, and 150,000 lb Mo and other critical metals can be made available annually for recycling by a process developed by the Bureau of Mines. Stainless steel wastes pelletized with a portland cement binder were reduced in a small electric-arc furnace by a two-stage process to produce a recyclable alloy containing Cr, Ni, Mn, and Fe. The initial reduction was with carbon; the second, with ferrosilicon. Results are compared with previously reported laboratory induction melting tests. A 2,000-lb demonstration test of the process in a commercial electric-arc furnace is also described. Data are also presented on three 1,500-lb tests made using various slag conditions in the electric-arc furnace. Recoveries up to 99 pct of the Fe, Cr, and Ni contents of stainless steel wastes were obtained in using the process.

Jan 1, 1977

By J. Grumer

Nine dust and gaseous inhibitors of propagating coal dust-air flames (lean, stoichiometric, and rich) were evaluated in a newly developed 15-cm-id, 3.6-meter-long instrumented flame duct, under conditions such that wall quenching was virtually absent and the dust concentration was temporally and spacially uniform to within about t5 percent. Listed roughly in order of increasing efficiency, the inhibitors evaluated were rock dust (calcium carbonate), powdered oyster shells (calcium carbonate), Halon 1301 (trifluorobromomethane), Halon 1211 (difluorochlorobromomethane), sodium chloride, Super-K (potassium chloride), regular-grade fire extinguishant powder (sodium bicarbonate), Purple-K (potassium bicarbonate), and Monnex (potassium bicarbonate combined with urea). Experiments were extended to clouds containing 1 and 2 volume-percent of methane. The inhibition of lean, stoichiometric, and rich methane-air flames without coal dust was also examined in a few instances; results agreed with those obtained for coal dust-air flames.

Jan 1, 1971

By Maria I. De Rosa

Table 28 and figure 10 show the number of fires and fire injuries for surface sand and gravel mines by state during 1990-2001. Table 28 also shows the injury risk rates, employees' working hours, and lost workdays. At surface sand and gravel mines, a total of 70 fires with 60 injuries occurred in 29 states during 1990-2001. Fifty-nine of the fires caused 60 injuries (none of the fires involved contractors). The yearly average was 5.8 fires and five injuries. The Ewhr value was 741 x 106 hr (Irr = 0.016), and the LWD value was 6,921. California had the most fires (nine fires and five injuries), followed by Michigan (six fires and six injuries) and Pennsylvania (five fires and five injuries). Of these states, Pennsylvania had the highest injury risk rate value (Irr = 0.052). Table 29, partly illustrated in figure 11, shows the number of fires, fire injuries, risk rates, employees' working hours, and lost workdays by time period. The number of fires and fire injuries show an increase during the second period followed by a decrease during the fourth period followed by a small increase during the fifth period and a sharp decrease during the last period. Employees' working hours increased during most of the periods. The Irr values follow patterns similar to those shown by the injury values.

Jan 1, 2004

By Thomas J. Peters

The U.S. Bureau of Mines studied the 3,500-acre Winegar Hole study area, Idaho, a legislatively proposed (101st U.s. Congress) addition to the Winegar Hole Wilderness, Wyo.; it adjoins the western boundary of the Wilderness at the Idaho-Wyoming border, about 15 m; east of Ashton, Idaho. The study was part of an Idaho Land Assessment Program to provide minerals information for land-use decisions, and ensure domestic mineral supplies. The study area is an east-west elongated, wooded plateau south of Falls River. Although the area is covered with surficial glacial deposits, it is probably underlain by volcanic flows; light-colored and mafic flow rock were noted in sparse outcrop. No mines, prospects, mineralized areas, or mineral resources were found in the study area during a literature and field search. The only nearby prospects include geothermal and rock aggregate (volcanic cinder) sites, and several placer claims. Although the Winegar Hole study area lies within a region of potential geothermal resources, no evidence of geothermal activity was observed. Rock in the area does not split into flat slabs, which could be useful as dimension stone, and would require crushing to be used 8S aggregate. Alluvium (placer) samples contain less than SO.01 per cubic yard gold (at a $350 per oz price); alluvial deposits are too small to contain gold resources.

Jan 1, 1992

To develop and design a bit that will rapidly drill smooth and precise instrumentation holes in soft rock. Approach Use a one-piece bit made by combining a drag bit and a diamond bit. Because a smooth-walled borehole with a precise diameter is needed for borehole pressure cells (BPC) and other borehole instruments, a diamond bit is usually used. However, diamond bit drilling is slow, and the bit will tend to bind when squeezing ground is encountered. On the other hand, the drag bit will cut faster, but the walls of the drill hole will be rough and the diameter will not be as precise. The combination will provide a bit which penetrates as rapidly as a drag bit, but retains the smooth-wall and precise borehole diameter of a diamond bit. How It Works A three-foot-length of EW-size drill rod is centered in a diamond bit by welding it to three equally-positioned spacers at each end of the bit. A drag bit is attached to the EW rod with a standard EW-to-drag bit adapter as shown in the diagram. Three equally-spaced diamond inserts are set to the desired hole size and welded to the diamond bit barrel behind the crown. These inserts increase the smoothness and precision of the hole by cut-ting away any hole closure. Three equally-spaced shims are set approximately 0.020-inch under the overall insert diameter size and welded to the rear of the diamond bit barrel. The combination bit should be used on a diamond drill with either water, mist or air as the coolant.

Jan 1, 1982

By H. J. Sloman

"INTRODUCTION Industry, including coal mining, has come to realize that to prevent accidents the human element must be given more consideration than was customary in the past. In formulating safety rules and regulations and in the enactment of laws governing mining, too often enforcement is emphasized rather than the means of gaining willing compliance.' The purpose of this paper is to call attention to the human side of accident prevention, and the approach to this important and much-discussed subject will deviate somewhat from the usual discussions.The human being is a complex mechanism, both physically and mentally. It is difficult to establish a common denominator for the actions of humans, except in general. In establishing mining laws, rules, regulations, and standards, the ultimate objective should be to gain the best possible response of workmen, so that optimum results in accident prevention may be obtained. The complexity of human beings is apparent when the many ways 1n which they differ are considered. Some of these differences are manifested in emotional and phlegmatic types, degrees of intellect or native intelligence; and in hopes, desires, aspirations, and philosophies of life. How much simpler ac¬cident prevention would be if the response to laws, rules, regulations, or standards were equivalent to the definite movements of puppets responding to pulls on strings. Each time, the strings are pulled in exactly the same way, the puppets will respond in exactly the same manner. Human beings, although having many similar characteristics, do not respond uniformly to identical ""string-pulling""; therefore, much study is necessary before the desired re¬sponses can be obtained. To achieve the ultimate in accident prevention, it must be ""worked at"" constantly. Regardless of the adequacy of safety laws, rules, regulations, or standards, good accident records will not ""roll in"" if dude consideration is not given to the personal traits of those most likely to be involved in accidents."

May 1, 1948

By Andrew B. Cecala, Edward D. Thimons

"The Bureau of Mines has recorded a number of different background dust sources that significantly contaminated the air breathed by bag machine operators. These background sources, observed at five different plants over the past 2 years, can expose bag machine operators to more significant dust concentrations than the filling process itself. To keep bag operator exposure within acceptable dust levels established by the Mine Safety and Health Administration, U.S. Department of Labor, the significance of these background sources must be realized, and the sources must be identified and controlled. The purpose of this work is to identify common background dust sources and show the significant effects that they have on the bag operator's overall dust exposure. INTRODUCTIONThe purpose of this report is to identify some common background dust sources in and around the bag-filling area. Although these background dust sources are of ten unrecognized, they can be more significant sources of contamination than the dust generated from the bagging process.The bagging of mineral products into 50- and 100-lb paper bags is common throughout the entire mineral processing industry. Bagging is performed by a bag operator who sits in front of a two- or four-station fill machine. The bagger's function is to attach empty bags to the fill nozzles as filled bags are ejected from the machine. If the product being bagged is extremely fine (smaller than 200 mesh), the bag operator's dust exposure is usually one of the highest in the plant.The bag operator is exposed to two primary dust sources. The first is product blowback during the bag-filling cycle. This occurs as excess pressure is released from around the fill nozzle during filling. As the excess air forces its way out of the bag, product is forced out with it. This blowback of product leaving the bag creates a considerable amount of dust. The second major source is the ""rooster tail"" of product thrown from the bag valve and fill nozzle as the bag is ejected from the fill machine. Since the bag is pressurized as it leaves the machine, product spews out of the valve for a few seconds."

Jan 1, 1986

By C. A. Herbert

"The Workman's Compensation Law of Indiana, enacted in 1915, amended in 1917, 1919, 1923, and 1927, and in 1929 named the Indiana Workmen's Compensation Act of 1929, provides for a weekly compensation for disability due to accidents of 55 per cent of the average weekly wage of the employee, to start on the eighth day of disability. Compensation is computed from a maximum and minimum weekly wage of $30 and $16, respectively. Thus, the maximum weekly compensation is $16.50 and the minimum $8.80; the total compensation paid is not to exceed $5,000.In addition to the compensation the employer is required to pay all medical, surgical, hospital, and nurse fees for a period of 30 days and may be required to pay such fees for an additional 30 days at the direction of the Industrial Board of Indiana. In the case of fatalities the employer must contribute $100 toward funeral expenses.The law also stipulates that ""the employer shall keep a record of all injuries, fatal or otherwise, received by his employees in the course of their employment,"" also that the employer shall report within one week of their occurrence all accidents that cause either the death of the employee or the loss of more than one day's work. However, no standard form is furnished or required by the industrial board on which the employer shall keep a record of accidents, neither is he required to report the time of return to work of the injured employee unless the period of disability exceeds seven days and the accident thus becomes compensable. Hence, no record is kept of noncompensable accidents other than the first report sent to the industrial board by the employer.If the employer were required to keep a complete and concise record of all accidents, in duplicate, on a special form either furnished or required by the board, giving all of the essential data in regard to the accidents, and if he were required to submit a copy of this record to the board at the end of the fiscal year, the data thus assembled would not only be of material assistance to the board, particularly in making up its annual report, but would also furnish information of much value in the study of accident causes and what may be done to remove them.Those industries that have made marked progress in reducing accidents keep such records, as it is only through a full knowledge of how accidents occur that intelligent steps can be taken to prevent their recurrence. Unfortunately, the mining industry as a whole in Indiana has not kept pace with many other industries in reducing accidents, and it is urged as an aid to improvement that a thorough and complete record of mining accidents be kept."

Dec 1, 1932

By C. P. Bowie

During the period of 10 years from January 1, 1908, to January 1, 1918, approximately 12,850,000 barrels of oil and 5,024,506,000 cubic feet of gas were destroyed by fire in the United States, entailing a total estimated property loss of $25,254,200. During this period 503 fires were reported. As is shown in Plates I and II, 310 of these fires were caused by lightning and 193 by all other causes. The losses from the fires caused by lightning were estimated to be $11, 148,000, and from those due to all other causes $14,106,200. Directly and indirectly, the fires resulted in the deaths of nearly 150 persons and were responsible for almost as many more being permanently disabled. For the past three years the Bureau of Mines has been conducting investigations to determine the nature and the specific causes of these fires, with a view to suggesting means whereby they may be suc- cessfully combatted and, in some places, perhaps eliminated entirely. As the subject of oil and gas fires is necessarily broad, no attempt is made in this bulletin to treat it exhaustively; rather the bulletin aims to point out what has been done by operators in the past, and to describe various fire-prevention methods and fire-fighting appa- ratus which are being used or adopted by many of the larger oil companies. These methods and apparatus, it is believed, if uni- versally employed by operators, will largely decrease the present enormous annual losses. In the discussion of oil-well fires, the methods used in extinguishing several of the larger and more perplexing ones are described. As the right procedure for extinguishing any oil-well fire must be de- termined largely by local conditions, it is not probable that all of the methods used at some one fire, as described, will be applicable to a future fire. However, the operator, from these descriptions, may at least gain suggestions that will greatly assist him in fighting similar fires.

Jan 1, 1919

By Ron Merkel, A. Mayton

Operators of underground mobile equipment, particularly shuttle cars, are often exposed to significant levels of whole-body vibration (WBV) and shock. The human factors group at the NIOSH-Pittsburg Research Center has investigated the use of viscoelastic foam to reduce shock for the equipment operator and improve seats on mine shuttle cars.

By T. M. Barton

This paper presents several case studies in which a mechanics-based boundary-element program is used to back-calculate the surface subsidence associated with various panels at several northern Appalachian coal mines. The program used in this case study is called LAMODEL, which incorporates a frictionless, laminated overburden into a general-purpose displacement-discontinuity code primarily designed for calculating the stresses and displacements in coal mines or other thin-seam or vein-type deposits. In this paper, the program is used to calculate both the underground convergence and the resulting surface subsidence at five longwall panels and a room-and-pillar section. The fitted subsidence from the model is compared with the field measurements and analyzed. The results from this work show that the LAMODEL program is not as accurate as available empirical subsidence-predictive methods: the expected correlation between the geology and the optimum input parameters is not evident. However, for a mechanics-based program, LAMODEL does provide moderately accurate subsidence calculations, and it is one of a few programs that can even attempt to practically calculate both underground stress and convergence and the resulting surface subsidence.

By M. E. Poad, M. M. McDonald, J. C. Johnson, 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. In this study, borehole extensometers and other instruments were installed to provide data for model verification and to monitor shaft displacement. Results of a recalibrated two-dimensional model (UTAH2)confirmed the premining stability evaluation. However, after mining began, concern developed because of cracks and other signs of ground motion that appeared at considerable distances from the area of active pillar mining. An intense three-dimensional modeling effort using the computer modeling program UTAH3 was initiated. The results again showed the observed effects were within expectations and that the shaft would remain safe. Three-dimensional analyses of alternate pillar mining scenarios indicated that more of the shaft pillar ore reserve could be recovered than previously thought on the basis of two-dimensional analyses. This report focuses on startup and implementation of the three-dimensional model, calibration of the three-dimensional model, and application of the model to shaft pillar mining.

Jan 1, 1996

By Launa Mallett

This training material focuses on the content of emergency warning messages. Research has shown that when an emergency occurs, people often do not get the information they need for the purpose of taking appropriate action. This safety talk presents a procedure, using mental cues that can be used by senders and receivers of emergency warnings.

Jan 1, 1999