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By A. B. Hooker, L. C. IlsLey

The greatest hazard of early mining was from explosions of methane ignited by open lights . With the advent of safety lamps and forced ventilation this hazard was greatly reduced until the application of electricity to modern mining not only multiplied the sources of gas ignition but the accompanying , machines and haulage systems increased the amount of explosive dust , through which a methane explosion is more liable to become a major mine disaster , and thus greatly furthered the need of adequate ventilation to keep down the concentrations of methane . Adequate ventilation is still the best preventive of such explosions . However , even with a well laid out and controlled ventilating system the amount of air passing through entries and rooms is liable to vary within wide limits because of open doors , falls of rock , or other accidental causes . The percentages of methane under normal conditions should therefore be kept so small that they will not be increased to explosive proportions by short interruptions in ventilation . Mine ventilation and methane detection are inseparable safety precautions . The increasing importance of ventilation necessitates more accurato determinations of the methane concentrations throughout the mines . This paper discusses in detail some of the steps in the development of methane detection and specially notes the more accurate detectors now available . One of the earliest means of detecting methane was by a candle . About 1835 , John Buddle , Sr. , a noted mining man of his period , when questioned by a Parliamentary Committee as to the safety of using candles , replied :

Jun 1, 1933

"The Generic Mineral Technology Center on Respirable Dust was established in August 1983, at the request of the Bureau of Mines, to conduct research that affords ""...each miner the opportunity to work underground during the period of (his/her) adult working life without incurring any disability from pneumoconiosis or any other occupational disease"". The Center consists of the Mining and Mineral Resources Research Institutes (MRI) of The Pennsylvania State University (PSU) and West Virginia University (WVU) in association with the MRIs of the Massachusetts Institute of Technology (MIT) and the University of Minnesota (UMN). (FIGURE 34) Michigan Technological University (MTU) is also affiliated with the Center in the area of diesel particulates.The Center brings together experts concerned with particles causing potentially disabling or fatal diseases including pneumoconiosis (""black-lung""), silicosis, and asbestosis. The latter is of deep concern not just to workers in the mineral sector of the economy but also to the general populace. The primary goal of the Center is to reduce the incidence and severity of respirable dust disease through advancing fundamental understanding of all aspects of respirable dust associated with mining and milling, and the interaction of dust and lungs. The research program of the Generic Mineral Technology Center explores these scientific, engineering or medical concerns with the objective of refining existing strategies and developing new respirable dust control techniquesand technology that are consistent with the fundamental dust-lung interaction processes that lead to mine worker disability. The work concentrates on five areas (FIGURE 35):"

Nov 1, 1988

By Russell. Paul L.

"INTRODUCTION Preliminary reports by Bureau of Mines engineers 3/ and by the Federal Geological Survey 4/ suggested that exploration would discover substantial reserves of minable ore in the Contact mine, Grant County, New Mexico. During February and March 1943, a sampling program was conducted on this property under the direction of the author. This was art of a general survey of the manganese districts of southwestern New Mexico.In its program of exploration 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 each exploratory project as practicable soon as after its conclusion. The Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocer, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. S. Dean, assistant director. With respect to this report, special acknowledgment is due to C. H. Johnson, district engineer for New Mexico, and E. D. Gardner, regional engineer, and his staff, of the Central Region of the Bureau of Mines at the time of this work in 1943; also to Kenworthy, metallurgist at the Rolla. Mo., Laboratory of the Bureau of Mines, for work on beneficietion of the ore, and Sherman K. Neuschel, geologist of the Federal Geological Survey, for assistance in interpreting geological data at the project."

Oct 1, 1946

By D. B. Gawthrop

"In connection with the proposed use of Cordeau-Bickford to fire L.O.X. (liquid oxygen explosives) in well drill holes, the question has arisen as to the effect of very low temperatures on (1) the rate of detonation of Cordeau-Bickford; (2) the sensitiveness to detonation of its TNT filling; and (3) the lead covering of Cordeau-Bickford.The Cordeau-Bickford used in this investigation was the standard 6 mm. size, such as is regularly used in blasting, and was manufactured and furnished by the Ensign-Bickford Company, Simsbury, Conn. All pieces tested were taken from rolls, all of which were from the same melted batch of TNT in order that all the pieces tested might be as nearly identical as possible.Different portions of this Cordeau-Bickford were tested plain (not countered), countered, and double countered. The countering and double countering was carried out by the manufacturer prior to shipment.The determination of the temperature at the instant of making a test was accomplished by the use of a Leeds and Northrup potentiometer and copper constantan thermocouples. Each couple was made from No. 28 B & S gage wire with short junctions. One junction was inserted in a hole drilled by a No. 60 drill through one lead wall of the Cordeau-Bickford to approximately the opposite wall, so that this junction was in the center of the TNT filling while the other junction was immersed in ice water. The potentiometer readings in millivolts were converted to °C. from the calibration curve of the thermocouple wire,"

Jun 1, 1924

By C. B. Manula, R. L. Sanford, R. A. Rivell

A central requirement for using simulation models is the need for retrospect testing to validate experimental conclusions. Acceptance of a model by managers and safety practitioners is more likely to depend on its tested performance in-the field rather than on the underlying logic or the validity aspects of the model itself. It is here that simulation bridges the gap between theory and useful design procedures. The original version of the rail haulage sub-assembly was success¬fully tested in the field (Sanford, 1969). However, the case studies that were described here involved single-stage haulage and restricted jobtypes from UGMHS. Since this report together with Volume VI (Production Subsystem) describes extensive changes and modifications to the rail haulage sub-assembly and UGMHS, field tests were necessary to verify both the rail model and the linking concepts to the Produc¬tion Sub-system. Mine Description The candidate mine selected for model verification works the 6 1/2 foot Pittsburgh seam. Shaft openings are used for manways and ventilation and a dual compartment slope for materials handling. In the bottom half of the slope, a hoist with track handles supplies and equipment. In the upper half, a 42 inch belt conveyor travelling at 450 fpm moves coal from a rotary dump to the surface. The immediate roof is shale with the first 12 inches taken during development mining. About 4500 raw tons are produced daily from seven face units and one spare working three shifts. At seven of the sections,

Jan 1, 1974

By James E. Mills

Coal, in the process of mining, transportation, and handling and on exposure to the weather, is subject to more or less disintegration. This disintegrated coal is usually called "slack" and amounts often to a considerable percentage of the lump coal produced in the mines. If this slack coal is wasted the loss so occasioned ranges from 5 to 50 per cent, or even more, of the total coal mined. It is therefore clear that the utilization of this waste slack coal becomes a serious economic consideration. When the coal is suitable for the production of coke, the utilization of the slack presents no difficulty, as it is in demand for that purpose. If the coal does not produce good coke, but cakes rather readily, the slack can be used for boiler purposes, as it fuses together more or less quickly, and burns on the furnace grate without great loss. Coal that cakes less readily can be burned on grates of special construc- tion. When so used it is more troublesome to handle, and the waste is greater than when lump coal is used. Consequently the price of much of the slack coal for fuel purposes ranges considerably lower than that of the lump coal from the same mine. The full value of this slack coal as fuel can be realized by first form- ing the coal into a coherent mass or briquet, such briquets, when of good quality, being equal to or of greater value than the original

Jan 1, 1911

By J. F. Barkley

 This paper describes the method used and results obtained in testing a hand-fired down-draft furnace at a plant in Washington, D. C., in order to determine the method of firing that would give the best results with a minimu of smoke. The smoke regulations of the District of Columbia are very rigid, and are well enforced, A paragraph of the ordinance relating to furnaces other than household, reads, "The emission of dense or thick black or gray smoke or cinders from any smokestack or chimney 113ed in connection with any stationary engine, steam boiler, or furnace of any description within the District of Columbia shall be deemed, and is hereby declared, to be a public nuisance". This ordinance, if literally enforced, would eliminate all ordinary hand-fired grates and furnace combinations where coal other then anthracite is used. However, in several Gov- ernment plants where hand-firing of coal is still necessary conditions have been satisfactorily met by installing the down-draft type of furnace. In these plants, as at all hand-fired plants, considerable difference in operating details and methods is found. The firemen are paid day laborer's wages and are often inexperienced. The instructions of the furnace makers fre- quently do not appeal to the firemen, and are not closely followed, This is partly due to the necessity of running the boilers continuously at much higher ratings than were intended by the manufacturer. Tests were made on a Hawley furnace of this type to improve the methods of firing, particularly at the higher ratings.

May 1, 1924

By Vernom F. Swanson, George E. Fish

A study was made during 1959-60 of reported nelsonite occurrences in Nelson and Amherst Counties, Va. The investigation was limited to core drill- ing on one deposit and beneficiation studies on three deposits. Three diamond-drill holes totaling 562 feet were drilled on the E. M. Hughes property to determine subsurface continuity. Although outcrops as much as 30 feet wide were present on this property, the only nelsonite intersected in the holes ranged from 4 to 18 inches thick. The ilmenite content of the core ranged from 50 to 75 percent. These nelsonite deposits are of secondary importance as a source of titanium, being small, rarely exceeding 1,500 feet in length and 30 feet in width, but they are high grade. Due to the proximity of some of the bodies it might be possible to mine several of them as one operation feeding one mill. Electromagnetic separation on composited samples recovered 83.0 percent of the Tio as an ilmenite concentrate in 68.5 percent of the weight. Two flotation procedures were developed. The first method, using oleic acid as a collector and fluo silicic acid as an apatite depressant on deslimed feed, produced an overall recovery of 59.3 percent in batch tests. The second procedure eliminated desliming. Laurylamine hydrochloride removed silicates in an acid pulp followed by an alkaline apatite flotation with oleic acid as the collector and dextrine as the ilmenite depressant. The ilmenite-rich tailing represented a 66.2-percent recovery of Tio in the batch tests.

Jan 1, 1964

By R. V. Ramani, V. T. Burgos, J. A. McClay

Summary Cost models have, long been confined to the accumulation and analysis of static-data.. While historical and time study data are valuable for control of existing operations, for new systems and equipment, and for projections, they need to be adjusted or modified. The availability of computer-oriented systems simulators provide yet another method for costing these systems and equipment. This investigation has introduced a concept whereby continuous, variable data can be assimilated and analyzed through the combination of an economic analysis model, which includes a direct costing capability, with a systems simulator. This tandem operation permits increased flexibility and greater atten¬tion to detail in the evaluation of mining systems. The direct costing process is carried throughout the majority of the model operations. Labor and capital costs may be computed directly, even in the absence of the systems simulator, while operating costs re¬quire input parameters, at present, from the subsystems of the Master Design Simulator. Since the costs computed are based on the perfor¬mance of each individual machine unit, the model may be used to evaluate equipment compatibility, system interaction at the mining face, and the effect of system elements on total mining costs. Additional applications of the cost model include the following: 1. Complete mining systems may be evaluated, over their economic life, to determine the feasibility of a profitable operation. 2. Costs associated with mining various segments of the coal deposit may be computed as a guide to planning the mine layout and scheduling the sequence of operations or acquisition of new

Jan 1, 1975

Provide a more efficient method of cooling hot working environments in deep mines than is possible with single stage spray coolers or cooling coil heat exchangers. Approach Pass warm mine air through several stages of horizontally oriented water sprays fed by the chilled water supply of the mine. How It Works This concept extends the capabilities and potential applications of the coolers described in Technology News nos. 71 and 93. In this multi-stage design, hot ventilation air is cooled while passing through horizontal water sprays. Air enters the cooler through a diffuser section which slows the airflow and distributes it evenly across the cooler with a minimum of pressure drop. This ensures uniform exposure of the warm air to the cool water and consequent high thermal efficiencies. In the three-stage cooler shown, cold mine service water is sprayed from the first water stage manifold on the downwind end of the cooler. Slightly warmed water from this spray stage is collected in a sump, pumped and then resprayed through the second stage manifold. The process is repeated again for the third-stage. An overall counterflow heat exchange effect is thus achieved by exposing the hottest incoming air to the warmer, third-stage water spray first and to the coldest, first-stage water spray last. Wave plate eliminators can be employed between stages of water sprays to increase thermal efficiency or at the outlet to minimize the water discharged into the mine ventilation air. Cooled air can then be ducted to hot work spaces or simply released

Jan 1, 1985

To cool hot working environments in deep mines more efficiently, while substantially reducing the maintenance required by presently used cooling coil heat exchangers. Approach A mine's chilled water supply cools fresh air enroute to hot working areas, in an improved, direct-mixing heat exchanger. How It Works Warm, fresh ventilation air traveling through the mine's ventilation tubing enters the lower portion of the cooler heat exchanger through a large round opening designed to accept the ventilation duct. This air flow is turned upward and evenly distributed by egg-crate lattice and pair guide vans at the bottom of the cooler. On the diagram, warm air enters at the bottom left. As the air moves upward through the cooler, it passes through a plastic or wire mesh pad which is arranged so that it offers the most resistance to upward airflow immediately above the cooler inlet: this more or less equalizes the upward air flow along the length of the cooler. The air next moves through the cold water sprays, and then through a wire-mesh demister pad before exiting from the cooler at the top right. Cooling of the air is accomplished in several stages. As the incoming air passes through the lower plastic or wire mesh pad, it is exposed to water flowing downward through the pad to the water sump. This is water that has fallen from the sprays or dripped from the upper wire-mesh mist eliminator. This water is slightly warmer than the spray water since it has already done some cooling,

Jan 1, 1981

By M. J. Ferrante

Low-temperature heat capacities and high-temperature enthalpies for syn¬thetic Cu2S and CuS were measured. This investigation is part of the Bureau of Mines goals to provide thermodynamic data essential to the more efficient processing of copper ores, and thereby minimize the current dislocations in energy, environment, and mineral supply. Heat capacities were measured with an adiabatic calorimeter from 5 to 310 K, and resulted in S°298 = 27.76 for Cu2S(c) and S°298 = 16.05 cal/deg mole for CuS(c). Low-temperature values are tabulated for Cp°, S°, -(G°-Ho°)/T, and H°-Ho°. Enthalpies were measured with a copper block calorimeter from 298.15 to 1,600 K for Cu2S(c,1) and 298.15 to 780 K for CuS(c). The thermal behavior of CuS showed no transitions or other significant anomalies for the low- or high-temperature investigations. Cu2S showed reversible transitions at 376 K with an isothermal heat absorption of 0.865 kcal/mole, 720 K with an isothermal absorption of 0.280 kcal/mole, and approximately 1,400 K (congruent melting point) with a heat of fusion of 3.070 kcal/mole. High-temperature data are tabulated for H°-H°298, Cp°, S°, and -(G°-H°298)/T. Enthalpies are also expressed in equation form. The low¬and high-temperature data were combined with data from the literature to cal¬culate and tabulate ?Hf°, ?Gf°, and log Kf as a function of temperature.

Jan 1, 1978

By Isaac A. Zlochower, Kenneth L. Cashdollar

The Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health conducted a study of the explosibility of various metals and other elemental dusts dispersed in air, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating the explosion hazards in the minerals and metals processing industries. The dusts studied included boron, carbon, magnesium, aluminum, silicon, sulfur, titanium, chromium, iron, nickel, copper, zinc, niobium, molybdenum, tin, hafhium, tantalum, tungsten, and lead. The dusts were chosen to cover a wide range of physical properties - from the more volatile materials such as magnesium, aluminum, sulfur, and zinc to the highly "refractory" (very low volatility) elements such as carbon, niobium, molybdenum, tantalum, and tungsten. These flammability studies were conducted in a 20-L chamber, using strong pyrotechc ignitors. The experimental data obtained included the minimum explosible concentrations, maximum explosion pressures, and maximum explosion temperatures. A unique multiwavelength infrared pyrometer was used to measure the temperatures. For the elemental dusts studied, all ignited and burned as air-dispersed dust clouds except for nickel, copper, molybdenum, and lead. The measured maximum explosion temperatures ranged from -1 550 K for tin and tungsten powders to -2800 K for aluminum, magnesium, and titanium powders. The measured temperatures are compared to the calculated, adiabatic flame temperatures. In general, the dusts whose experimental temperatures were closer to the adiabatic values were those with the finer particle sizes, those that were more easily vaporized, and/or those that were intrinsically more reactive.

By John W. Frey

This paper presents one of a series of digests of foreign mining legis- lation and court decisions, which is being prepared in advance of a general re- port relative to the rights of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws governing the Portuguese overseas possessions, prepared from the best avail- able information in Washington, has been slightly amplified in accordance with suggestions transmitted through the courtesy of the Department of State by Fred Morris Dearing, American Minister at Lisbon.

Nov 1, 1929

By Guy A. Johnson

This Bureau of Mines report summarizes the results of efforts to develop reasonably priced, reliable mine shaft fire and smoke protection hardware for metal and nonmetal mines. The hardware was incorporated into a viable prototype system that would minimize fire and smoke hazards. The design of the system had to be sufficiently flexible to be utilized in a wide variety of metal and nonmetal mine shaft and shaft station configurations. As a result of long-term, rugged field tests, an improved (second generation) system was developed. The hardware is now commercially available.

Jan 1, 1978

By Frank J. Susko

The U.S. Bureau of Mines has developed a computer model to describe a flotation process. Coal data from conventional flotation has been converted to a simple, two-parameter kinetic model developed by Reuter and van Deventer (1,2)3. Each set of coal data was represented by two constants, a and ß, and an average flotation rate. The success of the model was demonstrated when the calculated and experimental recoveries showed good correlation. The two-parameter model allows complex data to be defined much more efficiently than traditional knowledge-based models.

Jan 1, 2010

By J. A. Lamonica

The Bureau of Mines studied two types of approved coal mine dust personal samplers to determine the effect of decreasing the amplitude of airflow velocity fluctuations on cyclone performance. Results indicate that more dust is collected when pulsation free flow is used. Velocity fluctuations were reduced by means of a pulsation damper; damper efficiency of about 85 percent was needed to reduce the fluctuations to an acceptable level. The data were obtained employing both pulsating and non-pulsating flow. A comparison was made of (1) the masses of respirable coal dust as determined by weighing and of (2) the particle size distributions as determined by an electronic counter. An empirical relationship is given between the ratio of masses collected using pulsating and nonpulsating flow (M') and the ratio of the maximum air velocity to the minimum air velocity (V') as measured in the cyclone entrance channel.

Jan 1, 1972

By Je M. Oh

The Bureau of Mines is conducting research to determine the high temperature oxidation resistance of substitute stainless steels (SS) containing two less strategic elements, Al and Si, instead of Cr. Chromium is considered to be a critical and strategic metal. Although the Cr content was reduced to 8 wt pct, the alloys showed better oxidation resistance than did 304 SS containing 18 wt pct Cr. Specifically, the alloys that contained Fe-8Cr-16Ni with combinations of Al and Si showed excellent oxidation resistance even at temperatures up to 1,000° C. In this study, the effects of the alloying elements on oxidation kinetics and morphology of oxides were investigated using a Cahn Rg electrobalance, scanning electron microscopy, an energy-dispersive X-ray analyzer, X-ray diffraction, and an electron microprobe. Aluminum and silicon additions in combinatin were more effective in providing oxidation resistance than either element was alone.

Jan 1, 1986

By Walter W. Fisher

Cement copper was flash roasted in a vertical tube furnace to convert the copper to acid-soluble oxides as part of a postulated process for refining cement copper by oxidation roasting, acid leaching, and electrowinning. The results of the study showed that the oxidation was a linear function of oxygen concentration between 0 and 20 percent, but above 20 percent oxygen there was no further increase in oxidation. Therefore, air was the optimum oxidizing atmosphere in this flash roasting system. The oxidation followed a parabolic rate law as the roasting temperature was increased from 400° to 800° C. Extrapolation of the data, based on the parabolic law, indicated that at 400°, 500°,600°,700°, and 800° C, the roasting times required for complete conversion to soluble oxides were 75, 37, 21, 7.7, and 4.6 seconds, respectively. Cyclic-roasting test results did not substantiate the predictions obtained through data extrapolation.

Jan 1, 1973

By D. A. Wilson

A process was developed on a laboratory scale in which a solid waste byproduct from refining of secondary lead was converted into three valuable products. Roasted lead blast furnace matte was leached with water to recover copper. This was followed by brine leaching to recover lead. Residues were finally smelted to yield pig iron. Copper was precipitated as cement copper and the lead product obtained was a mixture of pure 3PbO.PbC12.xH20 and Pb(OH)C1. Copper recovery was 89 percent and lead recovery was 96 percent.

Jan 1, 1967