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By E. F. Divers

This Bureau of Mines report describes the results of a program to develop small, rugged mechanical dust collectors (scrubbers) with high dust collection efficiency and low energy comsumption for controlling dust in coal mining operations. All of the scrubbers described are similar in configuration and are powered by 6-hp, 2,000-ft3/min vane axial fans. Air pressure differential is less than 6 inches water column. Height of the scrubbers? including fan is less than 14 inches, width is less than 16 inches, and length is less than 45 inches. The flooded fibrous-bed scrubber achieved respirable (less than approximatey 7 µm) dust collection efficiencies of 95 percent. The small-diameter-cyclone scrubbers showed about 92 percent efficiency and can be best where excess water is a problem. The wetted brush scrubber showed 88 percent efficiency at low cost, and the wetted fan scrubber showed a slightly lower efficiency (87 percent) but offered the smallest size and cost. A suitable water droplet eliminator is described.

Jan 1, 1978

By M. J. Sapko

The pressure and flame development of the methane-air-nitrogen system was investigated in the Bureau's l2-foot-diameter sphere to define buoyancy effects and to develop relationships for predicting venting requirements. Pressure rise (?P) is defined as a function of time (t) and nitrogen dilution and is shown to deviate noticeably from the cubic law (?P = kt3), depending upon the period of combustion and the mixture composition. Corresponding flame speed (Sf) and burning velocity (Su) data are given which show that Sf is time dependent and that Na dilution has a greater effect than air dilution in inhibiting the flame propagation. The Su data agree with "accepted" values and are unique in that they are based on much larger flames than those used in other investigations. Downward propagation limits are shown to depend mainly upon buoyant forces, which can affect the burning of even stoichiometric CH4-air systems. Theoretical expressions, based on the mixture burning velocity and expansion ratio, are given for predicting the venting requirements for ignitions of hydrocarbon-air-nitrogen mixtures in spherical or cubical enclosures.

Jan 1, 1976

By J. B. Zadra

Tungsten metal, chemically equivalent to commercial grade, is produced by electrolysis of impure tungsten compounds or scheelite in an alkali, phosphate or borate electrolyte. A preliminary investigation of fused-bath electrolysis shows the effect of electrolyte composition, temperature, and current density on current efficiency, yield, crystal structure, and purity of product. Experiments show that tungsten can be electrowon from scheelite in a fused alkali, phosphate, or borate bath with similar results. Studies on electrolyte composition show that the addition of sodium chloride is essential to both electrolytes in treating scheelite. Although its main function is to react with or flux the CaO, it also increases the bath fluidity. Temperature studies revealed optimum ranges between 900° and 1,100° C.; 900° C. proved satisfactory for tungsten trioxide, and 950° to 1,050° C. for scheelite. Current efficiencies were satisfactory for all current densities ranging from 10 to 57 a./dm.2. Yields were 400 to 650 g./kw.-hr. over the same current-density range. Crystal size and purity of the product are functions of temperature, current density, and amount of impurities in the electrolyte. Deposited crystals vary in shape from spherical grains to clusters of dendritic hexagonal needles, and in size from smaller than 35 to 570 microns. The purity of the tungsten metal produced ranges from 99.7 to 99.94 percent.

Jan 1, 1959

By E. P. Ferrero

Analyses of 38 crude oil samples from 25 fields in Algeria, Libya, and Nigeria are presented in this report. The 38 crude oils are listed alphabetically by country and field. Also shown are the geographic and geologic sources of the samples analyzed, the companies that supplied the samples, the general characteristics and analytical and computed data, and the production for the fields from which the samples were obtained.

Jan 1, 1966

By G. M. Martinez

The Bureau of Mines has investigated methods for the recovery of byproduct heavy minerals from sand and gravel operations in Oregon and Washington. These heavy minerals are not currently recovered except for gold in a few areas. The recovery of byproduct heavy minerals would provide a domestic source of minerals presently imported, and a more efficient use of domestic resources would be accomplished. Samples from more than 40 locations were treated by gravity separation to yield heavy mineral concentrates (black sands). Magnetite, ilmenite, zircon, rutile, chromite, platinum-group minerals, radioactive minerals and gold were identified in the concentrates. Individual zircon, ilmenite, chromite; magnetite, and gold products were recovered from selected concentrates by low-and high-intensity magnetic, high-tension, and heavy-medium separation techniques. The recovery for the individual mineral products ranged from 67 to 95 pct.

Jan 1, 1981

By George T. Faust

The petrographer engaged in examining the products resulting from the beneficiation of ores and rock minerals is constantly required to develop new means and methods of assaying microscopically the results of such operations. From time to time investigators have published descriptions of apparatus that have aided in solving problems in processes f physical separation. Thus, in 191.9, Coghill and Bonardi 31 published a paper covering the application of the binocular microscope and camera lucida to the microscopic analysis of pulverized ores. Similar work has been published by Schneiderhohn 4/, Schwartz 5/, and Head and his associates6/, 7/, 8/. The present paper goes further and considers application of the polarizing comparison-microscope to problems directly concerned with mineral dressing where it is desirable to compare analogous products, and in addition it suggests new uses in various related fields. This work was conducted under the cooperative agreements of the Southern Experiment Station of the Federal Bureau of Mines and. the University of Alabama.

Jan 1, 1940

By George Watkin Evans

The United States Geological Survey has estimated 1 that the State of Washington contains 11,412,000,000 tons of bituminous coal and 52,442,000,000 tons of subbituminous coal, in beds more than 14 inches thick. As the present rate of production is about 4,000,000 tons a year, Washington apparently contains coal enough to supply Pacific coast markets for many years. The character of the coal beds of Washington renders the production of clean coal very difficult, and a considerable proportion of the output is washed before it is marketed. In 1915 Washington ranked fifth among the States in the amount of coal washed, though only twentieth in total output. In that year 37.9 per cent of the coal produced in the State was treated in surface cleaning plants. On account of extensive folding and faulting of the coal measures, mining in Washington presents many difficulties; therefore a description of the methods employed at some of the mines may be useful in planning operations in other regions, and is presented in this bulletin. The coals of Washington differ in quality, ranging from true lignites in Cowlitz County in the southern part of the State to anthracites in the Mount Baker district of Whatcom County, in the north~ rn part. Most of the output consists of subbituminous and bituminous coals, the latter including both coking and noncoking varieties. Analyses of the coals of the State and descriptions of the beds from which the samples were taken have been printed in publications of the United States Bureau of Mines.2 Details of coal beds and analyses of the coals of King, Kittitas, and Pierce Counties have also been published by the Washington Geological Survey; 3 and most of the coal beds of the State are described in some detail in a bulletin of the United States Geological Survey.4 In 1918 mining was in progress at 72 mines in the State 4a; 46 of these mines each employed more than 10 men underground. These mines were distributed as follows: Thurston County, 1; Lewis County, 7; Kittitas County, 14; King County, 16; Pierce County, 6; Skagit County, 1; and Whatcom County, 1. During that year a total of 5,847 men were employed, 4,172 underground and 1,675 on the surface. The average number of days worked in the State was 275, and the average yearly output per man was 706 tons. Coke is made only in Pierce County by four companies, which have a total of 341 beehive ovens. In 1918 they produced 93,699 tons of coke. Up to 1919 mining machines were little used in the State. In 1917 only 6.61 per cent of the coal :produced was undercut by machines. In that year 58.95 per cent of the coal was mined by hand, and 34.44 per cent was shot off the solid. The explosives used were as follows: Black powder, 36.6 per cent; dynamite, 38.l per cent; and permissible, 25.3 per cent. The State of Washington is divided naturally into two parts by the Cascade Mountains which extend north and south somewhat west of the middle of the State. The coal areas east of the range will hereafter be referred to as eastern Washington-though nearly all of it is west of the middle of the State-and that on the west side as western Washington. The geographical distribution of the coal fields is shown in Plate I. Exploration of the State has not been exhaustive enough to preclude the possibility of discovering, besides the foregoing, other districts that contain deposits of coal in commercial quantities.

Jan 1, 1924

By Eugene H. Skinner

This Bureau of Mines report describes the fieldwork and subsequent analysis to determine physical properties, stress distribution, and several aspects of rock behavior as a necessary evaluation for a typical mine opening. All work was done at a test site on the 3300 level, Crescent mine, Coeur d'Alene mining district, Idaho. Free field stress beyond the influence of the opening was also determined. Conventional overcore technique with the three-component borehole deformation gage developed by the Bureau of Mines was used in three drill holes. Three field verification tests were performed using a gage newly developed by the Spokane Mining Research Center in an approach herein termed "initial deformation method." Use of this method validated that aspect of overcore theory which predicts that similar deformation effect occurs in the wall rock around the perimeter of an opening in rock under stress. Also described are all drilling procedures and performances. Physical property determinations were made on rock samples obtained from the three overcore drill holes. Twelve physical properties with a total of [532] values were obtained at various drill hole orientations and depths. Exhaustive statistical tests were utilized in the analysis of these physical properties. Further elaborated are statistical inferences based on these analyses. Extensive analysis and interpretation of Crescent mine geology are also described.

Jan 1, 1974

By Irving Hartmann, John Nagy, Donald Mitchell

"SUMMARY AND CONCLUSIONThe test data indicate that water infusion of the Pittsburgh coal seam does not reduce the amount of fine dust produced during mining operations to the extent reported elsewhere. Wide variations in the amounts of dust collected in the air current were noted in duplicate samples and repetitive tests. Changes in depth and location of the infusion holes and amount of water injected and addition of a wetting agent to the water had little effect on the amount of dust liberated.Water was forced readily into the coal. Some water flowed out along the cleats, but an appreciable amount remained in the seam. Little or no water pene¬trated the coal seam above the upper infusion holes.The average dust concentration (with and without infusion) in the return air, 40 feet outby the working face, was 25 million particles per cubic foot during undercutting, 20 million during drilling, 75 million during shot firing, and 20 million during hand loading. At the working face the average concentration was 3 to 6 times higher. The concentrations were measured at an airflow of 1,600 cubic feet per minute (c.f.m.) at the face.On the basis of this short investigation, no final conclusions can be made on the effectiveness of water infusion in reducing the amount of fine dust liberated during mining in the Pittsburgh coal seam. However, the data indicate that dust reduction resulting from infusion would be small.INTRODUCTIONThe production of fine coal dust is an inherent part of nearly every phase of mining. The use of large, high-speed continuous-mining machines and other mechanical equipment has increased dust production. In addition, in coal seams that have been subjected to high pressures for a long period, and particularly in dry and friable seams, some very fine dust is in the seam before mining. Much effort has been devoted to allaying and collecting at its source the fine coal dust released during mining. One of the comparatively recent techniques that has been developed for this purpose is infusion of water or other liquids into the coal seam. This method consists of injecting water under pressure into a coal seam to neutralize the fine dust released during mining. The water generally is introduced through bore holes in the face before undercutting."

Jul 1, 1957

By Frank E. Cash

"INTRODUCTION The iron—ore ranges in the Lake Superior district are the Marquette in Michigan, Menominee and Gogebic in Michigan and Wisconsin, and the Cuyuna, Mesabi, and Vermilion in Minnesota. These ranges produce about 85 percent of the iron ore mined in the United States. Accident experience in connection with this production is better than that of the regions producing the remaining 15 percent. Production and shipments vary slightly from year to year but closely approximate each other over a period of years.This information circular supplements, continues, and combines the data in Information Circular 7321,2/ including figures of 1944 and 1945.During the 6—year period 1940 to 1945, inclusive, 481,485,475 long tons of iron ore was shipped from the Lake Superior district. 4/ Michigan and Wisconsin shipped 93,787,648 tons, or 19,5 percent of the total, and employed annually an average of approximately 14,300 men; Minnesota shipped 387,697,827 tons, or 80,5 percent, and employed annually an average of approximately 9,300 men. The tons produced per man employed is much greater in Minnesota than in Michigan and Wisconsin, owing to the large open-cut production in Minnesota."

Jul 1, 1947

These proceedings consist of papers presented at two Bureau of Mines Technology Transfer Seminars in early 1980 for the purpose of disseminating recent advances in mining technology related to surface coal mining reclamation.

Jan 1, 1980

By Virgil A. Marple

The objective of this contract was to conduct characterization, evaluation and/or calibration studies of instrumentation used for measuring the quantity of respirable dust in mining atmospheres. Initially, this work involved the upgrading and detailed evaluation of the aerosol test chamber and the development of impactors with respirable classification characteristics. These were used as standards in the chamber for measuring the quantity of respirable dust based on either the ACGIH or BMRC respirable dust criteria. A program was then conducted to calibrate several photometers. In addition, the mass sensitivity of the GCA RAM-1 photometer to water droplets in the respirable size range was determined. Three additional studies were also made in this program. First, an experimental study was performed to ascertain the effect of crosswind, cyclone orientation and particle size on particle sampling and penetration through the 10 mm Dorr-Oliver cyclone. Second, a theoretical study was conducted to refine the theory used to predict the particle collection characteristics of impactors. Third, filter samples with known quantities of diesel and coal particles were produced and delivered to the B. of Mines for testing a Raman scattering analysis technique to discriminate diesel particles in the presence of coal dust.

Jan 1, 1984

By A. B. Needham

A number of the pegmatites in the southern Black Hills of western South Dakota contain sheet mica; and as the demand increased during World War II the area became an important producer of strategic qualities of mica. During this period of maximum activity, the U. S.. Geological Survey made detailed studies of the geological structural control, the mineralogical associations, and the production Of many pegmatites in the Black Hills. On the basis of results of this study, and at the suggestion of the Geological Survey, several of the pegmatites were examined by the Bureau of Mines, and a few were selected for further investigation. Accordingly, the White Bear, Silver Dollar, Buster Dike, and Hot Shot mines were diamond-core-drilled in 1947. The Hot Shot mine was investigated further by deepening the shaft and crosscutting the pegmatite in 1948. The mica-bearing deposits occur in lenticular intrusions of pegmatite in schists of various mineral composition. Eleven diamond-drill holes, totaling 2,111.4 feet in length, were completed on the four deposits. The shaft on the Hot Shot deposit was deepened 44 feet to the 112-foot level, and crosscuts were driven from the bottom of the shaft to the hanging Wall and foot wall of the pegmatite. This publication briefly describes the location, ownership, and history of the deposits and gives details of the work done by the Bureau of Mines and the Geological Survey.

Jan 1, 1950

Laboratory tests were conducted by the U.S. Bureau of Mines to determine respirable dust reduction effectiveness of and interaction between face airflow and water sprays for a continuous miner. Increases in exhausting face ventilation from 3,000 to 9,000 cfm, in waterflow from 15 to 35 gpm, and in water nozzle operating pressure from 80 to 200 psi were evaluated. Results indicated that airflow had the greatest individual impact on reducing dust levels, with concentrations at return and operator sampling locations reduced by as much as 57% and 99%, respectively. Regression modeling was utilized to predict dust concentrations over the range of values tested for the control parameters. Interactions between the control parameters were significant and often defined an optimum level where further increases in that parameter failed to produce additional dust reductions. Increasing airflow to 8,400 cfm, waterflow to 25 gpm, and water pressure to 140 psi typically reduced dust concentrations at operator and return locations. Application of a control parameter above these levels can provide additional dust reductions if used in conjunction with appropriate levels of the other two control parameters. Otherwise, higher operator dust levels may result and can be attributed to increased rollback and/or airflow turbulence.

Jan 1, 2010

By John J. Sammarco

The U.S. Bureau of Mines has developed a regulated, intrinsically safe, rechargeable power supply for portable electronic equipment for underground use. The regulated output is ideal for microprocessor power requirements and is suited for operation in hazardous environments. Two rechargeable, sealed batteries are contained within the power supply. Provisions are made to use an external source of power if these batteries fail. Provisions are also made to charge these internal batteries when needed. The circuit is composed of three main circuits: the main regulator circuit, the input protection circuit, and the output protection circuit. The main regulator circuit provides remote voltage sensing, current sensing, fault monitoring, and internal thermal protection. The input protection circuit checks for excessive input current and low battery conditions. The output protection circuit contains two overvoltage detection devices. Schematics, a parts list, and a calibration procedure are provided in this report to enable readers to fabricate the power supply.

Jan 1, 1989

By A. D. Marcy

The Midnite Mine is an inactive, hard-rock uranium mine in Stevens County, WA. Oxidation of sulfide-containing minerals, primarily pyrite, in the ore body produces large quantities of acidic water. An interception system installed by the mining company limits the discharge of contaminated water from the mine. The U.S. Bureau of Indian Affairs (BIA) and the U.S. Bureau of Land Management (BLM) have been actively involved in planning remediation of the disturbed areas. To assist in remediation, the U.S. Bureau of Mines (USBM) initiated research to determine water quality and to define ground water flow characteristics. USBM personnel designed a monitoring network, supervised installation of sampling wells, and collected and analyzed water samples. This Report of Investigations describes interpretation of data collected between December 1989 and April 1992. The computer program WATEQ4F was used to identify aqueous species distribution and to calculate potential solid phase controls of solubility. To assist in interpretation of changes in water quality between sampling locations and to develop models describing proposed flow paths, the computer program BALANCE was used. Using output from these programs and field observations, a description of the chemistry along proposed ground water flow paths at the mine is presented.

Jan 1, 2010

By R. L. Soderberg

This paper is one of a series on mining methods and costs being published by the Bureau of Mines. It describes briefly the mining methods employed since the start of operations in 1937, with emphasis on the diamond-drill blast-hole method of ore breaking and slusher-drift method of ore drawing at the Holden mine of the Howe Sound Co., Chelan Division, Holden, Wash. The Holden mine is in the north-central part of the Cascade Range, 11 miles up Railroad Creek from Lake Chelan. The nearest railroad is at Chelan Falls, 40 miles by boat and 4 miles by highway from the mine. All freight comes into the mine and all concentrates are shipped out via Chelan Falls. The altitude of the main haulage level is 3,500 feet. Railroad Creek Valley is covered with a dense growth of fir and spruce, while most of the surrounding mountains are rocky, with sparse timber growth.

Jun 1, 1948

By J. Durkin

The Bureau of Mines has conducted field studies in coal mines throughout the United States to determine the effectiveness of electromagnetic techniques in locating miners trapped underground following a mine accident. Data from these tests have been used to generate models of expected signal and noise distributions as found above these mines. These distributions have aided in placing the expected performance of a through-the-earth electromagnetic communications technique into a probabilistic framework. Results show that at a 10% false-alarm rate, the expected probability o detecting a miner's signal" from a depth of 1000 ft is 54% at 500 ft it is 95%. These depths exceed the actual depths of 90 and 50%, respectively, of United States coal mines. Sensitivity studies have shown that at depth of 1000 ft, the probability of detection will improve approximately 2% for each dB of increase in signal-to-noise (SNR) ratio.

By James H. Aase

Shales from 10 locations in Michigan were sampled, tested, and evaluated to determine their suitability as raw materials for producing lightweight aggregate by rotary-kiln methods. Sampling procedures and the geology of the shale units tested are discussed. Preliminary testing in a muffle furnace preceded extensive testing in a l6-inch by 14-foot rotary-kiln. Rotary-kiln products from these shales ranged in weight from 35.5 to 61.2 pounds per cubic foot (pcf). Concrete test specimens made pith selected aggregates were evaluated to determine the qualities of the concrete. Compressive strengths of the concrete ranged from 2,830 to 4,240 psi after 28 days of curing. Unit weight of the concrete ranged from 94.8 to 101.5 pcf. Lightweight aggregate suitable for use in structural concrete meeting ASTM standards was produced by the rotary-kiln method using shale samples from two locations.

Jan 1, 1967

By D. H. Yardley

A major purpose of this contract was to evaluate a variety of dust suppressants to determine their effectiveness in mitigating dust from taconite tailings. During the course of the investigation tailings from pilot-plant tests of Minnesota copper-nickel ores became available and chemical binders were also tested for dust mitigation effectiveness on this mineralogically different material. Field-test plots were established on taconite tailings and wind tunnel laboratory tests conducted. The laboratory tests consisted of comparing treated and untreated samples at wind velocities of 40 mph using a weight-loss method and direct dust emission measurements. It was shown that the emission of fine dust from taconite tailings, in the range of 4.5 microns to 0.85 microns, could be reduced by 99 percent using certain chemical suppressants. It was also demonstrated that a straight water spray on coarse tailings (3/4" to + 10 mesh) reduced dust emission by 95 percent. Although eight different chemicals were tested, most of the tests were made using Coherex, ammonium lignin sulfonate and sodium silicate. These same dust suppressants were used, singly and in combination on almost 75 field-test plots. The Coherex appears to provide the best results in terms of economics and durability. Wind tunnel tests on treated and untreated Cu-Ni tailings demonstrated that applications of dust suppressants reduced fugitive fine dust by better than 99 percent.

Jan 1, 1980