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By Wilbur I. Duvall

The borehole deformation gage and overcoring techniques developed by the Bureau of Mines form one of the primary methods of determining in situ rock stress. This report describes a least squares method of calculating the average rock stress components in the horizontal plane from more than three diametral deformation measurements in a vertical borehole. This least squares analysis provides a means of determining the multiple correlation coefficient, the variance, and the scatter for a set of deformation measurements. From this information, confidence limits can be calculated for the secondary horizontal principal stresses and their directions. The material presented in this report can be used as a guide to the development of least squares solutions for stress measurement techniques other than the borehole deformation method. Since the statistical information that results from the least squares method is extremely useful in the interpretation of results, it is recommended that a least squares analysis be used on stress measurement data whenever possible.

Jan 1, 1979

Reduce fire warning time and avoid activation of false alarms in underground mines. Approach A heat activated stench/tracer gas system was developed which automatically releases the gas mixture into the mine ventilation air. How It Works A canister approximately 12 inches long and 3 inches in diameter is charged with 50 grams of ethyl mercaptan or other appropriate stench gas and 500 grams of instrument detectable Freon. The canister is then pressurized to 100 psi with nitrogen. A disc is used to seal the contents of the canister. A low-temperature alloy designed to melt at a predetermined temperature is used to restrain a spring loaded plunger. Upon exposure to heat, the alloy melts and the plunger is released. The plunger ruptures the disc and the mixture of stench and tracer gas is released from the canister. Canisters are mounted in areas of a mine which are susceptible to fire such as near

Jan 1, 1983

By Charlie Wyche

Principal mineral products in the Dominion of Fiji were gold, silver, pit and quarry construction materials, and cement. In the years 1978-79, the combined total value of these commodities accounted for some $15 million,2 or 85% of the total mineral output. Production of cement, sand and gravel, and quarry products increased substantially, but gold and silver output from Fiji's only operating metal mine continued the down-ward trend of recent years. Mineral exploration by several international mining companies as well as by local prospectors was being carried out over much of Fiji, and a number of interesting prospects were discovered. One of these, a medium-size porphyry-copper prospect in the Namosi area of Viti Levu, W88 at a mining feasibility study stage. At Mount Kasi on Vanua Levu, an extensive program of geological sampling and mapping W88 being conducted, and surface sampling and drilling W88 taking place at some base metal prospects in the south-central parts of Viti Levu. Also, high gold values in surface samples were reported at Vuda in western Viti Levu.

Jan 1, 1981

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

Measure the leakage through individual crosscut stoppings quickly and economically so that the worst ones can be identified and repaired. (Typically 60 to 80% of the air supplied to a mine short circuits before reaching a working face.) Approach Most of the leakage through a permanent stop-ping is channeled through two windows in a temporary stopping, and air velocities through the windows are measured; leakage is determined from a formula. How It Works A temporary stopping made of plastic brattice is erected in the same cross cut as the permanent stopping, either upstream or downstream. The brattice is fastened to the roof, bottom, and ribs of the entry with spads. Normal leakage of brattice was allowed for in deriving formula, and does not effect results. For best accuracy the brattice and the stopping should be separated by a distance of one hydraulic diameter.

Jan 1, 1979

To develop a magnetic levitation transport system that can reduce the cost and improve safety in transporting coal from the face of underground coal mines to the surface. Background Many conventional mining operations use conveyor belts to transport coal from an underground face to the surface of the mine. The Mag-Lev Transport System design replaces conveyor belts with magnetically levitated coal haulage containers moving through a dedicated pipe¬line. Cost estimates, based on current design data, show the Mag-Lev Transport System would have operating and capital costs that are less than or equal to those of an equivalent-capacity conveyor belt system. The safety hazards associated with conveyor belt systems include exposure to moving parts and pinch points, potential fire hazards due to mechanical friction, and the exposure of miners to respirable dust. These hazards would be eliminated or significantly reduced by this novel technology. Approach The Mag-Lev Transport System uses magnetic levitation technology that allows noncontact, frictionless conveyance of a levitated body within a dedicated transit corridor. The mag-lev technology utilizes two types of permanent magnets coupled with an electronic position control system to achieve noncontact levitation. Levitation is provided by neodymium-iron boron (NdFeB) magnets mounted in the base of the haulage containers and inexpensive ceramic-5 magnets located in the bed of the transit corridor. An electronic position control system is used to overcome the inherent instability of the repelling permanent magnets. Proximity sensors, a signal processing circuit, electromagnetic actuators, and fixed ferrous side rails are the major components of the positioning system.

Jan 1, 1994

By Charles Vaught, Belinda Sue Mills, Henry P. Cole, William J. Wiehagen

This study reports the results of a survey of organizations that used problem-solving simulation exercises to support mine health and safety training. The exercises are designed to teach judgment and decision-making skills within two broad domains: (1) how miners respond to mine emergencies (e.g., first aid, self-rescue, and escape) and (2) how miners integrate safety concepts within the context and performance of routine production work. The simulation exercises were distributed by the Mine Safety and Health Administration's National Mine Health and Safety Academy near Beckley, WV. The present study focused on those organizations that ordered the exercises from the Academy over a 2-year period (1995-96). Researchers assessed how the materials were used and trainer perceptions of the impact of these materials on annual mine health and safety training . A total of 147 organizations ordered the exercises over the 2-year period. Survey responses were obtained from 52 of these organizations. Sixty percent of the respondents rated the exercises as more useful than traditional instructional materials, 40% as equally useful, and 0% as less useful. Most trainers (79%) felt that the exercises help them to make better use of workers’ knowledge and experience during training. Many (71%)also reported that the simulations helped to improve the effectiveness of their instruction and promoted a problem-solving approach to their training. Fifty of the fifty-two respondents reported that they would like to have new simulations developed. A large majority showed a proactive interest in helping to develop and field test new exercises. Ninety-four percent of the trainers judged the exercises as a good value; 92% planned to order more simulations in the future. Based on this study, recommendations are offered for the continuation and expansion of simulation exercises as one method for occupational health and safety training.

Jan 1, 2001

By Van E. Shaw

Bastnaesite is a natural rare-earth fluorcarbonate of the cerium group that affords an abundant and high-grade source of the lighter rare-earth elements. A simple and efficient method has been developed by the Bureau of Mines for extracting rare-earth compounds from this mineral. Digesting of a flotation concentrate with sulfuric acid converts the rare-earth compounds from fluorcarbonates to sulfates. Action of the acid releases gaseous com-pounds of fluorine and silicon, leaving the sulfated material free of these elements; carbon dioxide from carbonate decomposition is eliminated at the same time. Calcining the sulfated material at 1,200° F. renders the gangue constituents insoluble, whereas the rare-earth sulfates are left in water-soluble form. Leaching with water yields a solution of pure rare-earth sulfates. Bastnaesite could become prominent as a source of cerium-group rare-earth elements. It is rich in the light rare-earth elements and comparatively easy to process; reserves of the mineral are extensive enough to supply a greatly expanded market for many years.

Jan 1, 1959

Develop an improved downhole geophone system with enhanced signal/noise ratio for collecting cross-hole seismic data used in tomographic reconstructions. Background The Bureau of Mines is conducting research in the use of cross-hole seismic tomography for detecting and monitoring leach solution flow during in situ mining. This technique requires the use of a downhole seismic energy source in one borehole and a downhole wall-locking receiver (geophone) in another borehole separated from the first by the region to be investigated. Bureau research personnel chose a commercially available air gun for use as the downhole seismic energy source. Unfortunately, commercially available downhole wall-locking geophones that the Bureau tested were difficult to operate in the field, often unreliable and generally inadequate in terms of their signal/noise ratio. Therefore, research personnel began to experiment with an alternative down-hole geophone design that could be used to collect adequate data in a wide variety of borehole and cross-hole field situations. Approach An attractive alternative geophone design would be one that would incorporate a pneumatically operated wall-locking system. As an integral part of the Bureau's existing field system, a portable, high- pressure/low-volume air compressor would have sufficient capacity to operate the air gun as well as several small high-pressure pneumatic linear actuators. This approach was the simplest and most compatible with the research activities being conducted at the site.

Jan 1, 1991

By S. R. Borrowman

Physical beneficiation, leaching, and solvent extraction investigations were made to recover a high-grade thorium oxide product from Bald Mountain, Wyo., conglomerate. The monazite in the Bald Mountain deposit contains 8.8 percent Th02 and, therefore, is higher in thorium content than the usual domestic or foreign monazite. A sample of composited drill cuttings for the study contained 4.3 pounds of monazite per ton of are. The work showed that the monazite, although unusually fine grained and friable, could be concentrated by tabling and magnetic treatment to yield a product assaying 5.65 percent Th02 with a recovery of 61 percent of the thorium. Subsequent decomposition of the concentrate by treatment with sulfuric acid and solvent extraction of the resultant solution with a primary aliphatic amine yielded a thorium oxide product of 99-percent grade.

Jan 1, 1962

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

SUMMARY The objective of this program was to develop a system to extinguish coal mine fires by remote sealing of the underground passageways. The system developed had to be versatile enough to function under a wide range of operating conditions, including large variations in passageway geometry, depth of mine, water conditions, both in the mine and at the surface, and rubble in the mine passage. The system developed had to include instrumentation for the remote probing of the passageway prior to sealing, a system for sealing the mine passages, and instrumentation for remote monitoring of the quality of the seal during and after construction. These objectives were successfully achieved during this program. The remote mine sealing capability of the system was satisfactc rely demonstrated in a field test conducted at the Eastern Associated Coal Corporation Federal No. 1 Mine in Grant Town, West Virginia. The remote sealing consists of: (1) A sonar initial probing system which can operate satisfactorily even in the presence of dense smoke. The system is capable of determining both the local passageway geometry, identifying the presence of cribs and other obstructions, and the position of the borehole in the mine passage. (2) A mine sealing material system which utilizes fly ash for making the complete seal or as a bulk filler in conjunction with a urethane, froth foam, seal topping system. The choice of using fly ash alone or fly ash with foam topping depends on a number of factors, such as quality of seal desired, time available per seal, depth of borehole, passageway geometry, and water holding require¬ment. The fly ash-foam seal is a better seal, capable of sealing against a higher water head than fly ash alone. The fly ash sealing

Jan 1, 1973

By D. A. Doughty

The Bureau of Mines developed two methods for determining iron II and iron III in 2- to 5-mg samples of coal using electron paramagnetic resonance (EPR) spectrometry. One method used solid coal samples; the other method used aqueous solutions. The method using solid samples was more simple, technically, but required the use of X-ray fluorescent analysis, or another independent method, for determining total iron in the samples, and the results were subject to some uncertainty. The method using aqueous solutions appeared capable of greater certainty and did not require additional methods of total iron analysis but was more involved procedurally. The coals analyzed were found to contain much more iron II than iron III.

Jan 1, 1973

By Gregory J. Chekan

In order to reduce waste and improve resource conservation, mine planning, and development, the U.S. Bureau of Mines is investigating multiple seam interactions associated with longwall mining. Longwall gate entry and panel stability have been influenced by previous mining in coalbeds above and below a mine in Virginia that operates in the Lower Banner Coalbed. Directly superjacent, approximately 115 ft, the Upper Banner Coalbed has been partially worked by room-and-pillar mining. Directly subjacent, approximately 730 ft, the Tiller Coalbed has been worked by partial room-and-pillar retreat mining. The study mine has experienced problems during development of gate entries in areas of overmining and undermining. It is anticipated that stress fields associated with adjacent mining may further affect gate entry stability and face advancement during the extraction of the longwall panel. To assess overmining and undermining effects on ground stability, the Bureau gathered geotechnical information at the site. Headgate entries and pillars were instrumented and monitored to study loading behavior as the longwall face approached and passed potential problem areas. Measurements indicate that although increases in average pillar pressure were greater than predicted values, previous mining in adjacent coalbeds had little effect on headgate stability.

Jan 1, 1989

By M. O. Renwick, Paul Zinner

"INTRODUCTION In September 1943, the Bureau of Mines conducted a limited program of churn drilling on the Winskell property in the Shullsburg area of Lafayette County, Wis. The work was undertaken as part of a general investigation by the Bureau of the zinc-producing area of southwestern Wisconsin at a time when special effort war being made to increase the production of metals necessary for the war program.Drilling described supplemented a previous drilling program conducted by the Vinegar Hill Zinc Co. The results of both programs encouraged subsequent investigation by the Cuba Mining Co. and eventual development of the Andrews mine.ACKNOWLEDGEMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by such project as soon as praticable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the investigative work, and prepares the final report."

Aug 1, 1947

By W. M. Weigel

"Sand is one of the commonest materials for industrial use, not only as a building material, but in many industrial processes. The general name applies to all grades, from the comparatively impure, unsorted product used in concrete, to especially sized products of extreme chemical purity. Various definitions have been proposed, all more or less open to objection, as they fail to cover special applications. One is: ""Sand - The fine granular material naturally or artificially produced by the disintegration or crushing of rock or slag"". This does not fit the definition of sand as understood by geologists, who consider sand only as a naturally formed product. Another is: ""Sand - The fine granular material naturally produced by the disintegration of rock"". This does not take the chemical com-position into account, and for practically all uses, except in concrete and plaster products, a material composed predominantly of silica or rather quarts is implied.Sand for special purposes usually requires different methods of preparation from those where the ordinary mixture of sizes as naturally occurring are suitable. One of the classes requiring the most uniformly sized grains is sand blast sand.Sand Blast SandThe use of the sand blast has increased rapidly during the past few years. It was formerly used almost entirely in the foundry to clean and remove inequalities from rough castings. This is still the most important application, but in addition, it is now employed for the removal of paint from old surfaces, carving and engraving on stone and marble, glass cutting, cleaning or renovating the rails of stone and brick buildings that have become discolored, preparing the surface of metals for the electrolytic bath, putting the final finish to metal surfaces, and has even been proposed as a means of channeling or cutting out blocks of stone in the quarry."

Jun 1, 1924

By W. R. Reed

Dust dispersion modeling is a subject that has had a large amount of research activity. Much of the research has focused on large-scale global or regional dispersion models. Other models have been created for industry-specific purposes. Furthermore, some of the past research has focused on dust dispersion modeling in the mining industry. This report presents the various dust dispersion models that have been developed specifically for the mining industry. The report first gives a brief background of the regulatory environment that helped to promote development of such models. It then presents an overview of the mathematical concepts used in this dispersion modeling. Finally, each of the various models developed for the mining industry are described, along with their associated mathematical algorithms and any field validation conducted on the different models.

Jan 9, 2005

By H. W. Lang

The Bureau of Mines conducted an investigation to observe the effect of cetane improvers upon nitrogen oxides concentration in diesel exhaust gas. Amyl nitrite and amyl nitrate were used as additives to the fuel used in a four-cycle, single cylinder type test engine. It was concluded that nitrogen oxide concentrations were not enhanced at fuel-air ratios above 0.03 pound of fuel per pound of air.

Jan 1, 1969

By George J. Conroy

Types and causes of short-circuit and open-circuit faults in mine portable trailing cables are discussed, and techniques for locating these faults are described. Time domain reflectometers (TDR) , tone generator, infrared sensing, and high voltage methods are covered. The paper summarizes Bureau of Mines research, including development of a ~DR/tone generator sender with auxiliary probe.

Jan 1, 1975

By J. L. Ellenberger, P. W. Jeran

A deep longwall coal mine was instrumented with a three-dimensional microseismic system in order to help determine the exact strata mechanics associated with the rock failure, redistribution of stress and the associated gob formation from the longwall. Overall, 5,000 well calibrated seismic events were recorded during the mining of the panel. Analysis of these events showed a close correlation between the seismic activity and advance rate, and that the majority of the recorded seismic activity occurs in the immediate area of the advancing longwall face.

Develop a curved ray geotomographic program with constraints to counteract non-uniqueness in order to improve the reliability of seismic tomographic imaging of geological structure in mining regions. Background Seismic tomography provides a two-dimensional image (tomographic reconstruction) of the distribution of the seismic velocity in geologic structures using measured travel times of seismic waves crossing the area. It can provide a more complete representation of features be¬tween boreholes than other crosshole processing methods that measure only average properties or borehole logging methods that measure properties only near each borehole. Seismic tomography has many mining applications. They include locating geologic structures of contrasting seismic velocity, detecting fractured regions where the seismic velocity is low, and monitoring solution injected above the water table where the increase in saturation increases the seismic velocity. Thus, tomographic imaging techniques show great promise for detecting and locating geologic hazards that affect the productivity, safety, and environment of mining operations.

Jan 1, 1992