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The Federal Mine Safety and Health Act of 1977* defines respirable dust as dust measured with a device approved by the Secretary of Labor and the Secretary of Health and Human Services [30 USC 842(e)]. The approved sampler for respirable coal mine dust is the coal mine dust personal sampler unit (CPSU) [30 CFR 74; Jacobson 1971; Jacobson and Lamonica 1969]. The CPSU is generally called the 10-mm nylon cyclone, although the 10-mm nylon cyclone is actually just one component of the CPSU. The CPSU may either be mounted on a worker (with the sampling head positioned in the breathing zone for personal exposure monitoring) or in a fixed location for area sampling [Tomb 1990]. The CPSU consists of a pump unit, a sampling head assembly, and a battery charger if rechargeable batteries are used in the pump unit [30 CFR 74.2]. The sampling head assembly contains two stages. The first stage is a 10-mm nylon cyclone, which has collection characteristics similar to an elutriator. The amount of dust penetration depends on the flow rate [Jacobson and Lamonica 1969]. The second stage is a membrane filter (vinyl, pore size 5 pm) that collects the dust passing through the cyclone. The dust collected on the membrane filter is weighed to a precision (standard deviation) of 81 pg [Parobeck et al. 1981], and the respirable dust concentration in the mine atmosphere is then determined from the mass of dust collected and the volume of air sampled [Tomb 1990].

Jan 1, 1997

By Willard L. Hunter

The separation of tantalum and columbium by solvent extraction was under-taken as part of the Bureau of Mines research program to improve methods for extracting, separating, and reducing these elements to metal. The diethyl ketone aqueous HCl-HF system was one of several systems studied to determine the effect of metal and acid concentrations in aqueous solutions upon the transfer of tantalum and columbium into selected ketones. The tantalum-columbium oxide mixture used in this investigation was obtained by chemical extraction from Geomines slag. The investigation showed that tantalum 99.4 percent pure and columbium 97.2 percent pure can be produced by the selective transfer of tantalum into diethyl ketone from a solution of 2-N HF and 1-N HC1. The relatively low acid concentration necessary for tantalum transfer and the excellent selectivity of the system recommend its use for the separation of tantalum and columbium.

Jan 1, 1961

By Stephen Gerard Sawyer

The Bureau of Mines developed a method for analyzing elastically certain types of protective cabs and canopies used on underground electric face equipment. The method is based on plane frame theory, and to be amenable to analysis by this method, cabs and canopies must contain symmetry about one plane. Additionally, protective structures with one or more top members in the long direction that do not frame into the columns should be approximately twice as long as they are wide and have two or more internal top members in the short direction. The assumptions and limitations of the plane frame method as regards analysis of three-dimensional cabs and canopies are discussed. A step-by-step procedure for application of the plane frame method is given, and three example canopies are analyzed following this procedure. Elastic strengths calculated for the three example canopies compare within 10 percent of those computed by the more complicated space frame analysis. Formulas employed in plane frame analysis of cabs and canopies are given in the appendixes.

Jan 1, 1973

By L. G. Marsh

The manufacture of lubricating oils from wax-bearing crude petroleums involves the removal and recovery of the paraffin wax contained in the lubricating distillates. During this process several intermediate products are formed, among them the mixture of waxes and oils known to the refiners as "foots oil." Because of its complex character, foots oil is little understood, and therefore methods of handling it in refineries are often inefficient. The Bureau of Mines is studying the manufacture of lubricating oils, and during the work has investigated the redistillation of foots oil. This report gives in brief the results of the investigation, and recommendations based upon it.

Jan 1, 1926

By Nicholas P. Kripakov

The U.S. Bureau of Mines examined the applicability of existing material models to solve practical geotechnical mining-related problems by solving a yielding pillar stability problem considering confining effects on strength. Numerical difficulties normally encountered with modeling strain softening behavior were eased with a simplified computational procedure using a quasi-elastic approach to account for residual strength after initial failure. Although in agreement with a confined-core pillar design method using actual mine conditions that include mine layout geometry, overburden geology, and rock properties of the deposit and surrounding structure, the results cannot be verified because measured field data are not available at this writing.

Jan 1, 1981

Provide an improved, rugged, reliable, cost-effective automatic fire protection for mine haulage trucks. Approach Systems that automatically sense and extinguish fires on haulage trucks were designed, built, and in-mine tested. How It Works Temperature sensors mounted above the engine of the truck detect the heat from a fire while it is still small and controllable. A cab-mounted control panel warns the operator of the fire emergency and then automatically triggers the discharge of 60 pounds of multipurpose dry chemical extinguishing agent (from storage tanks through hoses and nozzles) into the engine compartment. If desired, the control panel can be field-adjusted by changing one resistor to delay the discharge for up to 60 seconds to allow time for the operator to stop the truck and shut down the engine. The system can be assembled with either pressurized storage tanks, or a combination of non-pressurized storage tanks plus separate pressure cartridges. This pressure source option is one of the improvements of this system over the earlier systems described in Technology News No. 11. Other improvements are a simplified control circuit and an improved sensor.

Jan 1, 1980

By J. I. Paige

The Bureau of Mines, U.S. Department of the Interior, conducts research on methods to minimize the requirements for mineral raw materials through conservation, substitution, and increased minerals and metals recovery from primary and secondary domestic resources. To further this goal, prior Bureau research had devised a pyrometallurgical technique (RI 8211) to recover metallic iron and copper from molten copper smelting furnace slags by carbothermic reduction. As a continuation of this Bureau research on the carbon injection technique, reverberatory and electric furnace slags were treated in an 800-kva electric arc furnace by simultaneously top feeding the slag and injecting coke breeze into the bottom of the molten bath. Results of the tests show that 76 to 89 pct of the copper and up to 48 pct of the iron contained in the smelting furnace slag were recovered in a metallic phase, while 56 to 82 pct of the carbon injected into the sys-tem was utilized as the reductant. Laboratory evaluation has shown that the metal product, which contains 86.9 to 95.0 wt-pct iron and 1.3 to 4.1 wt-pct copper, will be a satisfactory medium for recovering copper by cementation. The expected energy consumption for the process is 110 kwhr per ton of molten slag treated and 520 kwhr per ton of solid material charged.

Jan 1, 1982

By S. J. Page, J. A. Organiscak

Dust surveys were conducted around small truck-mounted rock drills operating at surface coal mines to assess their airborne respirable dust generation and in-service dust control methods. Of four out of seven drills sampled, respirable dust concentrations measured around the drill deck ranged from 8.68 to 95.15 mg/m with3concentrations ranging from 1.37 to 2.69 mg/m at distances 12.2 to 30.5 m downwind of these drills. The other3drills had noticeably lower respirable dust concentrations measured around the drill deck at or below 1.30 mg/m.3Rotoclone-type dry dust collectors were commonly used with dust being emitted from around the drill deck shroud, collector exhaust, and collector fines dumping. Wind speed and direction was also a factor in the dust concentrations measured on the bench. Dust control modifications were made to three rock drills to reduce their airborne dust emissions. Dust controls tested included water injection into the Rotoclone exhaust, Rotoclone exhaust extension, improved sealing of drilling deck shroud, shrouding the Rotoclone hopper dump process, and wet drilling. These control techniques showed noticeable improvement in dust concentrations measured around the drills. Finally, repositioning the drill operator showed that operator dust exposure can be improved by avoiding the dust cloud around the drill.

Jan 1, 1995

Objective Develop a method to warn of hazardous conditions and enhance safety during operation and inspection of vertical mine shafts and hoists. Background Mine hoisting is the most critical and potentially the most dan¬gerous operation in underground mining. Many hazards are related to falls of miners and materials, ground instability, and malfunction or lack of safety devices. All have the potential to cause a cata¬strophic accident. A condition known as "slack rope" is particularly dangerous, expecially if it occurs without the operator's awareness. The most common occurrence of slack rope is in metal or nonmetal mines that have a history of ground control problems near the "haft. Approach Studies of hoist safety features and Mine Safely a and Heath Administration (MSHA) accident statistics suggests a need to measure wire rope tension, conveyance speed and position, and shaft guide misalignment. The most accurate data are obtained directly from the conveyance. Such data could warn of potentially dangerous situations during hoisting operations, as well as during inspections, maintenance, and lowering of large equipment. Figure I shows the concept for monitoring wire rope tension, conveyance position, and guide displacement. Progress to Date A conveyance-mounted system has been developed that monitors rope tension: hoist conveyance position, speed, and load; and shaft guide misalignment. A "flex-beam" load sensor mounted just above the- conveyance protects against slack and tight rope. The measurements are transmitted 60 times a second via wireless equipment from the conveyance to the hoist room. An encoder mounted on the conveyance eliminates the need to correct the position because of rope stretch. Figure 2 shows the encoder wheel and guide displacement sensors being mounted on a cage in¬spection deck. A potentiometer monitors misalignment of the shaft guides during inspections. Information about the cage or skip can be acquired by the shaft inspector using a hand-held indicator. Inspection can also he conducted remotely from a station or hoist room using the wireless link to a laptop computer. Figure 3 shows test results from a simulated slack rope condition. Patent Status NIOSH has a patent pending on this device entitled "Cable-Load¬Sensing Device." For More Information NIOSH is seeking cooperators to assist in further tests of this technology to improve hoisting safety. Additional information can he obtained by contacting Michael J. Beus, Steven Iverson, or Elaine Cullen, Technology Transfer Officer, NIOSH, Spokane Research Laboratory, Spokane, WA 99207 at (509) 354-8000.

Feb 1, 1998

By Jack A. Touseull

The Bureau of Mines has developed a simple stereographic method of analyzing the orientation of single and intersecting planes of weakness in vertical pillars of parallel symmetry. From this method, it can be determined if planes of weakness transect the full horizontal cross section of a pillar. A major finding resulting from this method was that intersecting planes of weakness can transect the full horizontal cross section of a pillar even though the individual planes do not. This paper provides step-by-step instructions for using this method.

Jan 1, 1977

By Kenneth H. Johnston

Information and data necessary for research on improving methods of oil recovery from low-permeability reservoirs and for comparison and evaluation of performance of such reservoirs with those producing from more permeable sands were obtained. Core analyses, well logs, production tests, well stimulation techniques, primary and secondary production records, and data on two water-flood projects were examined for wells producing from the Bartlesville sand, West Avant field, Osage County, Okla. Overall recovery from the study area was generally poor with only 9.0 percent of the pore volume recovered to January 1, 1968. Larger fracture treatments (8,000 to 12,000 gal) could have resulted in an increase in primary oil recovery. Secondary recovery by water-flooding accounted for only 1.9 percent of the pore volume because of the inability to control the large volume of injection fluid that escaped from the flood patterns and the excessive volumes of water produced with the oil. Future waterflood development in other low-permeability reservoirs should include the drilling of new input wells, use of injectivity surveys to locate possible natural fracture systems, or zones of high permeability, and control of injection fluids by altering flood patterns and/or plugging of the more permeable zones.

Jan 1, 1968

Promote safer and more efficient mine operations by providing communications between personnel located anywhere in the mine. Approach A radio communications system was designed which takes advantage of existing mine wiring such as telephone lines or electric power cables. The existing wiring distributes radio signals throughout the mine, making communications possible between roving miners, vehicle operators, dispatchers, and other personnel. How It Works Research has shown that medium frequency (MF) signals (300 KHZ-3 MHZ) can couple onto and re-radiate from nearby conductors. This effect is known as parasitic coupling and re-radiation. In a mine, these conductors include electric power cables, control lines, telephone lines, trolley lines, as well as metal water and air pipes Since all underground mines require these conductors for normal operations, the necessary network already exists and expands automatically as the mine is developed. A radio communication system has been developed that uses the parasitic coupling and re-radiation characteristic of MF. Using this system, whole mine radio coverage can be achieved without the need to install or maintain communication lines. The system consists of mobile transceivers for roving personnel and vehicles, and fixed-location base radio stations and repeaters.

Jan 1, 1982

By D. R. Babich, E. R. Bauer

US. National Institute for Occupational .Safety and Health (NIOSH) researchers are conducting a Cross-sectional survey of equipment noise and worker noise exposures in the mining industry. Surface and underground limestone is one commodity recently sun eyed. The sound levels of milling and processing equipment were recorded to identify noise sources. Full-shift worker noise exposures were completed to determine the exposure of various occupations. This article presents the results o f the noise research conducted in both underground and surface limestone manes, detailing the equipment likely to cause worker overexposures, and the occupations experiencing overexposures. Implications for worker noise exposure reduction are also reported.

By Paul T. Allsman

SCIENTIFIC inquiries concerning phenomena that may influence mining technology were widely publicized during the year. The deep-hole drilling project "Moho," 3 the use of nuclear explosives underground, and the recovery of minerals from the depths of the sea became subjects of scientific and general discussion. The mining industry continued to watch these developments with keen interest: but its more immediate concern was the increasing tempo of competition between mineral commodities, the domestic producers of these commodities, and foreign sources of supply. The competitive situation has intensified the industry's efforts to develop more efficient new mining methods, as well as to improve the efficiency of present practices. The attitude of the industry was well illustrated by rapidly expended use of low-cost ammonium nitrate explosives, the establishment of rigid schedules for equipment maintenance, and close attention to the detailed costs of production. The complexity of planning a new coal mine is aptly illustrated by the editors of Mechanization in the April 1959 Issue, in which they outline the cost of developing a mine and the various problems, factors, and decisions involved.4

Jan 1, 1960

By Thomas H. Dubaniewicz

The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory conducted a study of laser safety in potentially flammable environments. Researchers measured threshold igniting powers as a function of beam diameter for butane and propane-air mixtures by laser-heating targets placed on optical fiber tips using a 1064 nm laser. The minimum igniting powers for propane-air and butane-air were about 250 and 300 mW, respectively. Threshold igniting powers for propane-air were approximately proportional to beam diameter for beam diameters from 0.1 to 2.0 mm. Results suggest that relatively powerful beams may be used in these atmospheres without causing ignition, provided the beam diameter is controlled. Threshold ignition delay times using 91125 and 62.51 125 pm fibers were approximately proportional to the inverse square of the laser power. Ignition delays were about 45 ms or longer for laser powers up to 800 mW. Preproduction samples of a commercial optical fuse prevented ignitions under selected test conditions. A self-healing effect was observed for one sample. Comparisons are made with the results of other researchers. O 2006 Laser Institute of America. Key words: propane ignition, butane ignition, laser ignition, nonbeam hazards, fiber optic fuse

May 3, 2006

Improve surface mine haul-age truck safety and efficiency by providing a means for sensing the weight and distribution of the truck's load. Approach The safety hazards and the economic implications of overloading mine-haulage trucks were analyzed to determine the net effect of that practice on mine operations. The analysis indicated that: Ten to 25 pct overloading is typical; Higher haulage, tire, and maintenance costs occur due to overloading (a 20 pct overload was estimated to increase operating costs 7 pct per ton); Ten to 15 pct of haulage? truck injuries and fatalities are attributable to overload conditions, at a cost over one million dollars per year to the mining industry. Vehicle-weighing technology that conformed to the performance specification for an off-highway haulage truck overload detection system was selected for in-mine testing. How It Works Normally, volumetric estimates are made during the loading sequence which do not account for the varying ore density. Hence, the actual weight of a load is never precisely known. By providing a precise measurement, an overload detection system will not only indicate vehicle overloading, but will also show under-utilization of the truck. One system tested by the Bureau of Mines was the ?Load Analyzer" manufactured by Pactronics Corporation in California. This system consists of a meter-type analog readout for the cab console and three "Electrosensors" (linear variable differential transformers) attached to the main frame. Using conventional welding and brazing techniques, two sensors are attached between the front members of the engine sub-frame and the top of the left and right trailing arms (one sensor per arm). The same techniques are used to attach the third sensor to the rear centerline of the truck. between the main frame cross member and the A-frame. The readout unit on the cab console indicates by color-coding whether each sensor loading is under (green), at (yellow), or over (red) the pre-set rated load. The three-sensor configuration with in-dependent readouts also detects uneven distribution of the load.

Jan 1, 1984

Because surface mining removes the original plant cover from the land and exposes the soil, special care is needed. Until the mined land is stabilized by revegetation, snowmelt and rainfall can pick up sediment and erode mined lands much faster than undisturbed areas. Sediment control is an important aspect of protecting the environment during mining and reclamation because without it, large amounts of sediment can clog streams, increase the risk of flooding, damage irrigation systems, harm aquatic habitat, and limit the use of water for other purposes. Stream quality can be affected many miles downstream from the mine. Before SMCRA was implemented many streams were degraded by uncontrolled sediment from mining. Sediment is controlled through careful planning and a design that incorporates a variety of measures that work together to reduce soil erosion at the mine. Disturbed areas are graded, and some areas terraced, to achieve stable slopes, reduce runoff water velocity, increase infiltration, and divert runoff into drainage channels so that it flows away from unvegetated, erodible areas. Grading along the slope contour and scarify in gun vegetated slopes with bulldozer track marks help prevent erosion by slowing down the flow of water. Runoff from haul roads is controlled by culverts and roadside ditches. Sedimentation ponds or other forms of sediment control are required at all mines to minimize the amount of sediment leaving the site.

Jan 1, 1992

By Eric E. Cather

A mineral investigation by the U.S. Bureau of Mines revealed no mines or prospects and no past or present mining claims in the Agua Tibia Wilderness Study Area (WSA). The area is underlain mainly by weakly foliated gabbro similar to rock that has hosted gem- and lithium-bearing pegmatites in the Pala district about 6 mi to the south. However, no gem- or lithium-bearing pegmatites have been discovered in the WSA. Nearby quarries in the gabbro have yielded rock for facing and dimension stone. No sand, gravel, or energy (oil, gas, coal, or geothermal) resources were identified.

Jan 1, 1984

By E. Chin

Bangladesh, whose population probably passed 100 million by yearend, remained one of the poorest countries in the world, with a per capita gross domestic product (GDP) of $126.2 Its only economically significant mineral production was natural gas. A few other minerals or mineral-based commodities were also produced, generally for local consumption. These included cement, clays, nitrogenous fertilizers, limestone, salt, steel, and pilot plant production of ilmenite and rutile. Exploration for oil was a continuing quest, which was hindered by a lack of funding and a hesitancy on the part of foreign petroleum companies to make long-term or expensive exploration commitments. PODUCTION AND TRADE Production of natural gas continued to increase as more use was being made of the abundant gas reserves variously put at between 7 and 16 trillion cubic feet. The main consumers were nitrogenous fertilizer producers and electric powerplants, but other industries were converting to natural gas from imported coal or fuel oil wherever possible.

Jan 1, 1986

"There mines are located in out of the way places, where timber is scarce and its price high, the problem of protecting it from fire risk is of considerable practical importance. Scarcity of timber for mining purposes is commonly met with in the more arid parts of the country, where, so, mine timbers are most likely to become dry, and inflammable, and where, therefore, the risk from fire is accentuated. Any effective and cheap method of securing adequate protection of such timber at the lowest possible cost is worthy of careful investigation. The use of magnesite cement has been suggested in this connection.The necessary qualities for any substance for the use suggested above may be summarized as follows: It should be resistant to abrasion, and to impact and structural stresses. It should be durable when subjected to the action of the elements, and stable to any minor derangements of the base on which it is placed. It must be relatively unaffected by changes in temperature, by the action of water, and should adhere to the material on which it is placed, and it should also be free from shrinkage cracks due to setting up the material, Magnesite cement appears to fulfill the various conditions outlined above.The elasticity of such cement is the outstanding quality which makes it desirable for exterior work. It also possesses the ability to adhere to all materials in a marked degree. Its freedom from expansion and contraction after setting is one of the principal reasons for its adhesive quality. It may be applied to old brick or stone walls, even tho they have been repeatedly covered with paint, and the quality of adhearing to wood makes it possible to secure a weather-proof protection to the wooden casings and trim of exterior openings. The quality of adhesion and elasticity is easily proved by applying a 1/2"" layer to a 1"" board which has been first covered with metal lath. Such a board, about 8 feet long, may be repeatedly deflected about 3"" in the center without breaking the bond to the board, or causing any cracks to appear in the magnesia cement. The ability to resist fire as well as the possession of insulating qualities are also desirable characteristics of magnesia cement stucco.Magnesite cement stucco should be applied in two coats, each 1/4"" thick on various surfaces such as wood lath, metal lath, sheathing board, brick, hollow tile, or stone; care being taken as regards the presence of lime, unless the same has been rendered, or become inert as with very old, walls. The first coat made up to a consistency that works easily under the trowel is applied in the usual manner. No water should be added to the liquid chloride as it would alter its density, and injure the work. The second or finishing coat is then applied. The aggregates are different in each, and no other dry material should be added to them as they come to the trade. The cement may be applied in zero weather without damage. Setting is quite slow under such conditions, but the cement ultimately becomes hard. It should always be applied to a dry surface excepting that under certain conditions it is desirable to apply a solution of magnesium chloride before using the stucco."

Dec 1, 1919