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By Brian Kenner, Peter Swanson, Todd Krahenbuhl

NIOSH has developed an automated PC-based seismic event (induced earthquake) monitoring system for use in mine ground control studies. The distribution and coordination of data acquisition and processing functions across a local area network is a central feature of the system. Mine-wide installations utilize multiple, autonomous seismic networks located both underground and on the surface. Seismic event locations, magnitude estimates, and other processed data are distributed for display and analysis on network nodes both underground and in the offices of mine engineers and managers. This paper describes the system’s design philosophy, hardware and software components, examples of installations, and a few observational results.

By Hillary W. Clair

An equation is derived for the rate of reaction of a sphere of metal oxide in a restricted enclosure through which a reducing gas is flowing . The equation takes into consideration the reaction rate coefficient , transport through the gas and through the porous shell of reduced oxide , the rate of gas flow , and the volume of the enclosure . The equation serves as a model for predicting the course of reduction of a particle of metal oxide in a shaft furnace .

Jan 1, 1964

By P. Yant, R. R. Sayers, R. D. Lieitch

"PURPOSE OF INVESTIGATIONOf more than 300 bituminous mines examined by Crichton 5 and his assistants in connection with litigation in Indian Creek Valley, Payette County, Pa., only four were found to have alkaline water. That work and many observations from of the authors have shown the general prevalence or acid drainage from bituminous coal mines. In connection with investigations pertinent to coal-mine drainage that are being conducted by the United States Bureau of Mines, it was noted with considerable interest therefore, that a mine in the Thick Freeport bed about 20 miles north of Pittsburgh had no acid water in the workings, As it was thought that this condition might be common to all mines,this condition in this bed most of them were visited, samples of the outflow and from different parts of the mine inside were examined, and such general information as was available was gathered.ACKNOWLEDGMENTSThe authors acknowledge with thanks the courteous assistance of mine officials in connection with collecting the data for this paper, and of the analytical and coal laboratories of the Bureau of Mines for analyses."

Nov 1, 1932

By H. J. Sloman

Mining laws of the several coal-producing Stat e with respect to safety catches on mine cages and their testing are extremely variable and generally indefinite in scope. The most specific requirements are contained in the Coal Mining Laws of Washington,3/ as follows:

Jan 1, 1944

By J. H. Jansky, P. W. Jeran, G. L. Hassett, M. C. Irani

This Bureau of Mines report tabulates methane emissions from U.S. bituminous coal mines with daily emission rates of at least 100,000 cfd according to States, counties, and coalbeds. Most of the methane emitted is from mines in the Appalachian States. Total daily emissionin 1975 was 216.3 MMcfd, compared with 227.0 MMcfd in 1971 and 214.5 MMcfd in 1973. Thirty counties in nine States had daily methane emissions of 1 MMcfd or more, These emitted 93 percent of the total methane. The highest emissions were from Monongalia County, W. Va,, which accounted for 18.9 percent of the total. This was followed by Marion County, W. Va., 9.6 percent; Buchanan County, Va., 8.5 percent; Jefferson County, Ala., 6.1 percent; and Washington County, Pa., 5.9 percent. The Pittsburgh coalbed emitted 45.7 percent of the total methane, followed by the Pocahontas No. 3 coalbed with 12.9 percent. The report lists 196 mines, of which 60 had daily methane emissions of 1 MMcfd or more. Included in this compilation are the identification and thickness of the coalbed, methane emission, coal production and ventilation rates, number of drifts, shafts, and slopes used for ventilation purposes, shaft depth, age of mine, and gas-to-coal ratio.

Jan 1, 1975

As part of the overall development of a borehole mining system -develop backfilling techniques to reduce possible damage to the environment caused by either the cavities or the piles of sand tailings that result from in-borehole hydraulic mining. (Borehole mining is described in technology News No. 56.) Approach Water filled cavities at the bottom of boreholes are rapidly and economically backfilled by jetting a sand-tailings slurry underwater. How It Works The Bureau of Mines borehole mining system creates a cavity having a horizontal diameter of more than 50 feet. (See photograph). This cavity can be backfilled with much of the sand previously mined. The sand tailings or similar backfill material is dumped by a front end loader into a slurry mixing tank at the rate of about one ton every three minutes. Enough water is added to give a thick, but pumpable slurry. The slurry is pumped down the borehole through a string of 4-inch pipe to the cavity. After passing through a right elbow at the end of the pipe, the slurry is ejected through a nozzle. The resulting slurry jet emplaces the backfill at the outer wall of the cavity. To obtain an even distribution of fill in the cavity, the nozzle is slowly rotated. The nozzle and pipe assembly is supported from a turntable on the surface. See diagram.

Jan 1, 1981

By C. A. Komar

The Bureau of Mines is investigating possible applications of acoustic energy at sonic and ultrasonic frequencies in petroleum production. A phase of this work involves measuring sound velocity through petroleum reservoir rocks. References and abstracts were prepared as a bibliography to make available to others some of the material obtained from a literature search covering the past applications and the present uses of sound. Laboratory and theoretical studies of the various parameters that influence the velocity of sound in porous media account for the wealth of information now available. Velocity of propagation of sound waves in porous sediments as a function of depth is a quantity frequently measured. Velocity logging systems, capable of measuring speed of sound waves in underground formations penetrated by wells, have been developed for interpretative studies. The close relation between acoustic velocity and porosity makes it possible to determine porosity from velocity logs. Most velocity log interpretation in terms of porosity is based on a formula developed by Wyllie and others known as the time-average relation.

Jan 1, 1963

By James W. Hendrix

A survey of endomycorrhizal fungi occurring on orphan coalmine lands in Western and Eastern Kentucky revealed a great diversity of species present. Thus a large number of fungi are available for isolation and evalution for enhancing revegetation of mined land. Endomycorrhizal fungi isolated from orphan mines stimulated growth of sweetgum seedlings on mine soil at low fertilisation but inhibited growth at high fertilization; this growth inhibition at high fertilization did not occur with plants growing on peat-perlite. Banding of endomycorrbizal inoculum was not advantageous, compared with incorporation of inoculum throughout the growth medium, for production of mycorrhizal sweetgum seedlings. Newly reclaimed mine spoils were nearly nonmycorrhizal, compared with land reclaimed four or eight years earlier. A procedure for isolation of single-spore cultures of endomycorrhizal fungi was developed; this procedure is necessary for studies of ecotypic variability. A practical procedure using container-grown Pisolithus tinctorius-infected shortleaf pine seedlings for production of large numbers of bareroot pine seedlings infected with P. tinctorius for mined land reclamation was demonstrated.

Jan 1, 1982

Provide an unobstructive means of measuring small changes in distance from roof to floor or from rib to rib of a mine opening and the rate of closure in order to help operators of under-ground mines detect hazardous ground conditions. Approach A small ultrasonic measurement system was developed to detect g round movement and define closure rates. How the System Works The system contains two parts: a transducer and a readout device. The small ultrasonic transducer, similar to an audio speaker diaphram, is plucked with an ultrasonic frequency every six seconds. This frequency wave is sent through the air and reflected back to the transducer off any surface at which the transducer is pointed. The amount of time needed by the ultrasonic wave to make this round trip is accurately measured using a precise oscillator / timer and is converted into a measure of distance. The accurate 6-second time interval is used to convert any subsequent changes in the reading to a rate of change in feet per minute. Two readings are then displayed alternately on the readout instrument.

Jan 1, 1984

By Michael T. Nigbor

The Bureau of Mines assisted the Rocky Mountain Energy Co. in a pilot-scale in situ leaching experiment at Casper, Wyo., to determine if sulfuric acid can be used as a cost-effective alternative lixiviant (leachant) for uranium in situ leaching. This experiment, which lasted more than 2 years, is the first fully documented pilot-scale operation in which the leaching-restoration cycle was completed using sulfuric acid instead of the more common carbonate-bicarbonate leachant This report describes activities at the experimental site, presents extensive geochemical data from startup to site restoration, compares laboratory and field experiments, and discusses the environmental aspects of acid leaching. The data showed that sulfuric acid is apparently an effective leaching solution. Three to five grams of acid per liter of ground water resulted in a production solution grade of 80 to 100 ppm uranium. Restoration was successful, but required extended flushing. The pH was the last chemical parameterto return to baseline, requiring about 350 days. This was longer than was predicted in laboratory simulations. The data also showed that mobilization of toxic elements such as selenium, arsenic, radium, thorium, and molybdenum stayed within reasonable limits and quickly fell back to preleach concentrations during restoration.

Jan 1, 1982

By G. M. Kintz

"Methods and costs of rock-dusting bituminous coal mines have been discussed in various publications by the United States Bureau of Mines and others.3 This paper discusses the present methods and cost of dusting at the Swastika mine of the St. Louis, Rocky Mountain and Pacific Co., Raton, N. M.In the Swastika mine the recommendations of the United States Bureau of Mines with regard to rock-dusting are followed at least as well as in any mine in the States of Wyoming, Colorado, and New Mexico. This mine is located at Swastika, N. M., approximately 4 miles west of the town of Raton and is in the Raton coal seam. The mine is rated as gassy and produces approximately 1,000 tons of coal per day.A mining system known as the ""room-and-pillar with cut-offs"" is used which results in recovery of nearly 100 per cent of the coal. The mine employs approximately 250 men.Ventilation is maintained by a Sirocco fan so arranged that the air current may be reversed and exhausting approximately 130,000 cubic feet of air per minute at 3 inches water gauge. This fan is supplemented by two auxiliary fans for emergency use. Three main entries penetrate the hill in a straight line for approximately 8,000 feet. The haulage is through the center entry, which is also used as the intake in conjunction with a two-compartment concrete-lined shaft located at the end of the entries. The main return for 3,000 feet inby the fan is 12 feet wide and 7 feet high. For this distance the ribs have been reinforced by a wall made of coke-breeze blocks plastered over with cement. Solid concrete blocks are used for the top row of blocks of the wall. Steel 10-inch I-beams spaced 40 inches apart center to center are supported on these solid blocks and thus support the roof. The next 1,000 feet inby has the same area, but the cement blocks extend to the roof, as no crosspieces are needed. The airways are kept clean and well rock-dusted.A rather unique system is used to handle gas feeders along the intake and haulage entries. There these feeders occur in the roof or where gas is apt to collect in high points along the haulage, tin funnels as large as 3 feet in diameter are placed near the roof. From these a 2-inch or other suitable-sized pipe is run into the return through the wall of the nearest break-through. A valve on this pipe line controls the amount of air pulled. These devices keep the high places clear of any gas, even when strong feeders are encountered.Fifteen-ton electric trolley locomotives are used on the main haulage and approximately 30 roller-bearing oars, each having a capacity of approximately 3,000 pounds of coal, compose a trip. All loaded tripe carry steel drags on the last car, and automatic derails are located at advantageous points throughout the mine.All loaded trips are thoroughly sprinkled on the sectional partings and at the main parting. The track is sprinkled every idle day, or if needed, every day; from a large tank mounted on a truck hauled by a motor. Neither nozzle nor spray is used, as these were unsatisfactory. The water leaves the tank. through a 11/2-inch valve and is permitted to flow on the road through a horizontal 11/2-inch T. Water is obtained from filling stations located throughout the mine. It is stated by the officials that the use of this method of sprinkling permits the entire haulage roadbed to be wetted down in two hours."

Mar 1, 1930

Determine the effectiveness of remining operations in reducing contaminant load (acidity, iron, and sulfate) of discharges emanating from abandoned surface and underground coal mines. Background Until the implementation of remining initiatives, most States had regulations that held the operator remining an abandoned site responsible for preexisting acid mine drainage (AMD) discharges. For example, if a mining. company wanted to remine an area hydrologically connected to an existing AMD discharge, the company became responsible, as soon as the site was activated, for treating that discharge to meet effluent standards. If the mining operation improved the quality of the discharge, but the discharge failed to meet effluent standards, the company was held accountable for perpetual treatment. Because of this regulation, most mine operators avoided abandoned sites with minable coal reserves and AMD discharges. However, changes in remining legislation allow coal companies to be released from treatment liability as long as the post-remining pollution load does not exceed the pre-remining level. If remining can improve water quality through improved mining and abatement techniques, abandoned mine land (AML) areas that previously were liabilities could become

Jan 1, 1994

Provide long-term measurement of mine sidewall closure in backfilled stapes subject to flooding. Approach A water resistant extensometer is made by enclosing a rod-actuated transducer in a telescoping tube which is enclosed within an oil-filled outer housing. How It Works To assemble a water resistant extensometer, a cylinder -shaped transducer and two support rings are pushed into the small-diameter section of the telescoping tube where the transducer is held in place by friction. The outside of the small-diameter section of the telescoping tube is then greased and slid into the slightly larger-diameter section. See drawing. The cylinder-shaped transducer contains a potentiometer whose actuating arm is attached to a stainless steel extension rod that passes through one end of the telescoping tube. A similar rod is attached to the opposite end of the transducer body, and extends through the other end of the telescoping tube. A coil spring inside the large diameter end of the telescoping tube extends the tube

Jan 1, 1978

By J. A. Organiscak

Quartz dust is one of the most significant ongoing health concerns in coal mining today. Since the early 1980's, the U.S. Bureau of Mines has conducted numerous studies in underground and surface coal mines to identify the sources of quartz dust and its fundamental characteristics. This report presents data and conclusions obtained from these studies. The two most significant quartz dust sources were found to be the continuous miner excavating rock and the highwall drill operating in a rock overburden. The percentage of quartz was found to be higher in the smaller size fractions of dust when significant amounts of rock were mined by the continuous miner. Another factor theorized to affect quartz dust generation and size characteristics is the morphology of the quartz-bearing rock. Several laboratory studies were conducted to investigate capture efficiency of water spray technology and flooded-bed scrubbers with respect to the particle size of the dust. Water sprays and flooded-bed scrubbers were both found to be less efficient on smaller dust particles, and the scrubber was particularly less efficient on quartz dust. These results indicate that quartz control technology should be directed at controlling smaller sized dust particles.

Jan 1, 1990

By F. F. Aplan, J. A. Gutierrez-Rodriguez

"Contact-angle and flotation techniques were used to evaluate the influence of oxygen - both that inherent in the coal and that introduced by ambient temperature, aqueous oxidation - on a wide range of coal ranks. Oxidation was found to decrease the hydrophobicity and floatability of coal; with the effect being minor for coals of high rank but becoming increasingly important as the rank of coal is reduced. As an approximation, oxidation makes a coal behave as if it were one of lower rank. Frother only flotation' of coal· correlates with the captive-bubble contact angle whereas when oil is used as a collector, the flotation appears to follow the pattern shown by the water sessile drop on a fresh, un-reagentized coal surface. Coal recovery lost through oxidation may often be recovered by use of a variety of collectors, of which No. 2 foe! oil is among the best of those reagents tested. A simple alkali-extraction test may be used to estimate the influence of oxidation on coal preparation processes and use.INTRODUCTIONThe hydrophobicity of coal is not only a function of its rank but also of the extent of oxidation of the coal during and subsequent to its formation. Weathering and oxidation processes may proceed in-situ for coal deposits that outcrop near the earth's surface, or the oxidation of the coal particles may occur during mining, stockpiling or processing. Such oxidation, whether it affects the bulk-coal sample or on1y a thin outer layer on the coal surface, can dramatically influence the wettability of the particle and hence such processes as flotation, filtration, flocculation and dispersion.Many of the studies made on the oxidation of coals ·were designed to study its effect on flotation, coking or pyrolysis. The. present study 'is directed exclusively toward the effect of oxidation on the hydrophobicity and floatability of the coal. One of the first studies of the effect of oxidation on coal flotation was that of Sun [l] who found that as oxidation proceeds, coal becomes progressively more hydrophilic. Low-temperature oxidation (100-150°C for 250 h) generally lowered the coal floatability with an oily collector only slightly, but more extensive oxidation (200- 3500 C for 250 h) reduced coal floatability seriously. Sun also found that cationic amines were effective collectors for the oxidized coal which infers that oxidation makes the coal more negative in solution. He attributed the loss of floatability to be due to the accumulation of water-insoluble oxidation products at the coal surface. Gayle et al. [2] found that oxidation adversely affected coal flotation when an aliphatic-alcohol frother was used, though a small amount of oxidation appeared to improve the floatability of some coals using a kerosene-pine oil, collector-frother mixture in pilot-plant testing. Prolonged oxidation adversely affected the flotation recovery of the coals tested, the effect being more pronounced when an alcoholic-type frother only was used. They also noted that the reduction in floatability of lower rank bituminous coals was more affected by oxidation than was that of higher rank bituminous coals."

Jan 1, 1989

By James F. Neill, O&apos

Investigation of the Gilley fluorite deposit was based upon examinations made by several of the Bureau's mining engineers. Fluorspar was found in the dump talus of sloughed and water-filled trenches and shafts, and there were indications that faulting or other dynamic distortions favorable to deposition of this mineral in minable quality and quantity might exist. The inference was based upon a field study of the area and its comparison with fluorspar deposits in Kentucky. The proximity of this deposit to the iron furnaces at Gadsden and Birmingham was a factor that influenced its investigation, as the demand for metallurgical grades of this critical mineral is acute. The present supply for the district is obtained from out-of-State sources, and the value of any local deposit would be enhanced by the saving in freight charges. The Gilley fluorspar deposit is 17 miles east of Gadsden and 50 miles northeast of Birmingham, Ala. Mineral deposits occur as thin veinlets and small bunches of fluorite in upturned bode of siliceous limestone. The ore-bearing structure is a reverse fold, and the mineral deposit appears as a replacement along crumbled zone fractures of the contorted limestone.

Jan 1, 1950

By John C. Machisak

Injury data and experience, with related employment statistics, at coal mines in the United States for 1960 are presented in this publication under the following general sections: A General injury experience: Tables 1 to 6: Current data on number of injuries, decree of injury, frequency and severity rates, average severity, and related employment and production data by work location. B Selected injury experience: Tables 7 to 38: Current data on principal agencies of injuries, distribution of injuries by part of body injured, days of disability, extent of hand and machine loading, experience by employment and production groups, and various other operating factors and physical conditions related to the occurrence of injuries at the Nation?s coal mines.

Jan 1, 1962

By R. S. Dean

"Interest in the nitrogen content of steel has increased sharply in the last few years. Investigations have indicated that its presence in steel has an important bearing on high temperature brittleness3, magnetic properties4, room temperature hardening5, and shock resistance. The steel producer may therefore look forward with certaintly to the necessity of controlling this element in a considerable proportion of his product. The literature, however, reveals a great many contradictory statements concerning the percentage of nitrogen which must be present to produce given effects on the properties of iron and steel. Most of these arise from a misunderstanding of the nature of the iron-nitrogen diagram near the iron end and a lack of recognition of the effect of state of aggregation on physical properties although both have been fairly well worked out.My thanks are due to Mr. J. L. Gregg, Prof. R. H. Dowdell, Mr, R. F. Mehl and Mr. H. C. Vacher for suggestions in connection with the preparation of this paper, and to Mr. C. H. Hefty and Mr. G. T. Motok for furnishing a valuable bibliography and translations of articles by Must and Duhr.The iron-nitrogen diagram in the solid state, so far as it concerns the nitrogen content of commercial iron and steel, consists simply in a solubility curve increasing with temperature. The important thing about this solubility curve is that without cold wore the iron nitride when precipitated does not go into solution on heating for long periods below 300°C. This slowness of solution is probably due to the fact that iron nitride when present as a separate phase has at these temperatures an equilibrium pressure of several thousand atmospheres7 and that therefore each particle of iron nitride surrounds itself with a layer of nitrogen. The precipitation of such an unstable crystal presents points of interest thermodynamically but we can not go into these here. It is quite well established that it precipitate. It can not diffuse then unless this layer is broken through or the temperature and pressure are increased to a point where the nitrogen is absorbed at an appreciable rate in the surrounding iron. This rate will depend on the degree of unsaturation of the iron and the excess pressure of the nitrogen above equilibrium pressure. The degree of unsaturation is determined by the temperature alone so that the temperature at which the rate of solution of the nitride becomes appreciable will depend on the pressure of nitrogen developed. This, in turn, will depend on the balance between rate of decomposition of the nitride and the rate o: flow of the iron. In annealed iron, this temperature of appreciable solution rate is between 300 and 350°C.8 By cold work, however, the elastic limit of the iron is increased, and conditions for the nitride to go into solution are reached at a much lower temperature, giving rise to the so-called blue brittleness. This brittleness and hardening is due to iron nitride going into solid solution and is not precipitation hardening."

Mar 1, 1931

By D. Harrington, W. J. Fene, H. B. Humphrey

In the fiscal years 1946 and 1947 the number of mine explosions decreased compared with the preceding years. However, the loss of life was so serious during the fiscal year 1947 the period when the Government administered bi- tuminous-coal and lignite mines that from April to June 1947 extraordinary measures were taken in mines then under Government possession to obtain com- pliance with provisions concerning rock dusting, ventilation, and blasting that had not been followed. The great loss of life in explosions during the fiscal year 1947 as compared with 1944, 1945, and 1946 is not easy to explain, but the necessity for maintaining adequate protection has been definitely demonstrated. Management, workers, and inspection agencies alike must keep the mines reasonably safe against explosions or allow them to lapse into a condition where chance is the principal protection against disaster. The at- tention given to protecting coal mines and the men employed in them against mine fires, following the disastrous fires in 1944 and 1945, has at least tem- porarily controlled this hazard loss of life from coal-mine fires was re- duced to 1 fatality in 1947. The number of fires was also less, and progress has been made in reducing the heavy losses in both life and property from un- derground coal-mine fires that occurred in the two years mentioned. Fatalities from mine explosions during the past 6 fiscal years, July 1942 to June 1947, totaled 674, and there were 149 explosions; during the preceding 6 years there were 655 fatalities in 132 explosions. The 6 fiscal years 1942- 47 cover the active period of Federal coal-mine inspection. During the fiscal year 1947, there were 154 fatalities from explosions compared with 58 during the fiscal year 1946, 64 in 1945, 94 in 1944, 152 in 1943, and 152 in 1942.

May 1, 1948

By H. F. Yancey, E. Zane

"INTRODUCTION The term ""friability"" as applied to coal may be defined as the physical property of coal which expresses its tendency to become reduced in size during handling as a result of such external forces as impact and attrition. Thus friability is a quantitative concept and property, and hence can only be defined in relative terms or in terms of measurement. Methods of measurement are difficult to formulate and apply because coal is anything but homogeneous in physical structure and chemical constitution. aMoreover, friability itself is a composite property obviously dependent upon a group of other specific characteristics such as cleavage, fracture, tenacity, hardness, and elasticity, which vary from coal to coal with change in rank and even between individual coals of the same rank. These characteristics affect the friability values of different coals to varying degrees, but this fact does not impair the usefulness of and the need for friability measurements.The amount of breakage or degradation in size that a coal suffers in mining, preparation, and subsequent handling depends upon its inherent friability and the severity of the handling treatment which it receives from the time it is taken from the bed until it reaches the consumer. The value of the coal to the producer and jobber depends in large measure upon these same factors--friability and severity of treatment—because the larger sizes still command a premium in the ordinary market. Although much has been accomplished by the coal-producing industry in minimizing the breakage of coal in mining and preparation, it is apparent that additional reductions in breakage must await further improvements in design of coal-handling equipment. Such improvements will result from more intensive investigations of the extent of breakage or degradation in size occasioned by specific mining and handling operations and the development and application of standardized methods of evaluating friability.The work described in this report was undertaken to assist in the development of standard methods for evaluating the friability of coal. Specifically, the work deals with a Comparison of the various methods previously proposed for estimating the friability of coal and coal products. This same objective is now being sought at a number of other institutions, both in the United States and Canada, by a committee of the American Society for Testing Materials. It is believed that by providing additional information concerning a property of coal pertinent to its increased usefulness, the work described will supplement and increase the useful of the data which long have been, and still are being, furnished by the bureau of Mines on the composition of coals of the United States."

Jun 1, 1933