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By E. J. Gleim

The construction of explosion-proof electric mine equipment for operation in gassy coal mines of the United States was begun as early as 1903. In 1.906, similar equipment with special protective devices was built for export. An investigation of explosion-proof motors was conducted by the United States Bureau of Mines during 1910 and 1911. In other words, this was among the first efforts of the Bureau directed toward the saving of life and property subsequent to its establishment by act of Congress in 1910. In these early motors, those with special devices for relief of explosion pressures predominated. At that time it was generally considered that, by providing for pressure relief, the enclosures could be made lighter in weight because of the lower explosion pressures developed within.

Jan 1, 1954

By John B. Goodman

This report presents a study of a modification of the precision laboratory carbonization-assay apparatus that renders the unit capable of performance at low-, medium-, and high-temperature assay levels and permits, under controlled conditions, evaluation of the relationship between carbonization temperature and the yield of pyrolysis products. Second, the interest and value derived from the temperature study data directly apply to the particular semiplant carbonization processes and techniques currently being investigated in this laboratory. Data obtained with the assay apparatus enables the fuel technologist to predict the probable yields of carbonization products from pilot-plant operations under various carbonizing conditions. Data obtained with the assay apparatus has been used to predict the product yields of industrial carbonization plants at Kemmerer, Wyo., and Rockdale, Tex. The assay provides a useful tool in detecting, from the carbonized plant product, the degree of effectiveness of pilot-plant operation. Third, the residual volatile matter in some industrial carbons has broad significance. Evaluation of the volatile material remaining with or in the carbon may be assessed through the high-temperature-assay technique. The low-temperature carbonization assay devised by the writers has proved to be a versatile tool in predicting the probable product yields from pilot-scale carbonization processes. The apparatus described in previous publications has been modified to extend the range of testing above 500° C. without impairing the accuracy and reproducibility obtained in the low-temperature range. Results presented here include product yields from a typical Texas lignite and Wyoming subbituminous-B-rank coal over the temperature range 150° to 1,000° C.

Jan 1, 1958

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

Feb 1, 1998

By R. V. Ramani, S. Shankar

"A convective dispersion model has been utilized to calculate the real-time airborne dust concentration in mine airways using re-entrainment as the only source term for airborne dust. It incorporates two important sources of re-entrainment in mines -- air velocity and movement of objects. The model has a sink term accounting for the deposition of particles along the airway. The model is solved using a finite difference scheme which is coded for computer. The computer model outputs airborne respirable and total dust concentrations along the airway as a function of time. The real-time and average gravimetric concentrations from several in-mine experiments were compared with the results from the simulation of the experimental conditions. This model can be used for estimating airborne dust entrainment due to air velocity, equipment movement, and persons walking. INTRODUCTIONEdwards and Ford (1988) developed a model for coal dust explosion suppression and utilized a predetermined value of threshold velocity for flowing air to pick up dust from floor. Depending on the strength of the removal forces, re-entrainment can increase the airborne dust concentration in mine airways. The most prevalent forces causing re-entrainment in mine airways are the drag and lift forces due to flowing air, and removal forces due to the movement of persons and vehicles. Shankar and Ramani (1991) have investigated the unique characteristics of the re-entrainment phenomenon in mine airways. Experiments on re-entrainment of coal dust particles were conducted in mine airways, and in a wind tunnel (Shankar and Ramani, 1994a, and 1994b). The results from the two experimental studies were found to compare well (Shankar and Ramani, 1995). There is no reported model to determine the airborne dust concentrations due to airflow or persons walking under conditions existing in mines. The present study is a part of a continuing research project in the Generic Mineral Technology Center for Respirable Dust on the spatial and temporal behavior of airborne dust in mine airways (Ramani, 1983)."

Dec 1, 1996

By T. E. Purcell

(a) Moisture. - Moisture, "as fired," is specifically significant in pulverized-coal firing because of its effect upon the continuity of raw-coal feed to the pulverizer, pulverizer capacity, flame stability, and speed of ignition. The extraneous moisture content is a rough index of potential difficulties in unloading and maintaining the flow of raw coal to the pulverizer and of pulverized coal to the furnace, with the troubles increasing geometrically as the percentage increases. Sticking or other stoppage of coal flow at any point between the bunker and the furnace is especially serious with pulverized-coal firing because there is danger of immediate loss of output. Where moisture is a problem, the designer must exercise great care in the design of coal-handling and preparation apparatus.

Jan 1, 1951

By A. E. Wells

A critical study of the wet Thiogen process for extracting sulphur from the smoke of smelters is one of several investigations related to the general smelter-smoke problem that are being conducted under the direction of the Bureau of Mines. Part of the work done in the pyrometallurgical section of the cooperative metallurgical exhibit of the Bureau of Mines at the Panama-Pacific International Exposition during 1915 related to this investigation, and at the expiration of the exposition, the work was continued in the labora- tories of the Bureau of Mines in the Hearst Memorial Mining Building of the University of California, Berkeley, Cal., where a mining experiment station of the bureau has been established under the cooperative agreement with the University of California. Early in the spring of 1915, when plans were being made to co- operate with several metallurgical interests, the Thiogen Co. proposed to the Bureau of Mines that, along with the studies of various pro- posed methods for eliminating sulphur dioxide from smelter smoke, there should be included a study of the wet Thiogen process. In the study as outlined it was proposed to determine whether it would be technically and commercially feasible to use the, process for the recovery of elemental sulphur from the sulphur dioxide in waste smelter gases. Although there had been no large-scale work with the process, either in the laboratory or at a smelter, representatives of the metallur- gical and mining industry had shown considerable interest in the proposed method, and the desire had been expressed that a better knowledge of the possibilities of the process should be obtained. Thus, cooperation with the Thiogen Co. seemed justified by the in- terests of the metallurgical industry, and by the conservation promised by the recovery of a product of market value from what is otherwise a waste, and in some instances a serious nuisance. In accepting the responsibility for directing this investigation, the officials of the Bureau of Mines were necessarily free to conduct the work in the manner they considered necessary to determine the facts. It was also understood that any information obtained was to be made available to all who might be interested and might be printed in a Bureau of Mines report. To cover the cost of laboratory equipment and supplies, and the payment of salaries of assistants, other than Bureau of Mines employees, the Thiogen Co. in May, 1915, deposited with the cooperative metallurgical exhibit fund a sum considered sufficient to warrant starting the laboratory investi- gation. The origin and organization of this fund has been described by Clevenger and the author." In outlining the program for this investigation it was hoped that ultimately a small complete plant would be erected and the investi- gation center around the operation of the plant. However, pre- liminary to the erection of the plant, a laboratory study of the proc- ess was considered necessary, as the technical features of the process could be determined, it was believed, as satisfactorily on a smaller scale as on the scale first proposed. However, it was realized at the time that it would not be possible to determine so satisfactorily or definitely the commercial possibilities of the process on the scale of work adopted as in the larger operating plant. With this fact in mind it was planned that, if the study of the technical features on a laboratory scale gave sufficient promise of the process being commer- cially feasible, an operating unit should, if possible, be constructed later, and that more definite information concerning the commercial prospects should be determined. The investigations were started in June, 1915. In June and July work was confined entirely to small-scale laboratory tests, in which a careful study of the chemical reactions involved was made. In August, tests on a larger scale were started, and these were con- tinued until December, small-scale tests being made at the same time. On December 1, 1915, all work on the Thiogen process was discon- tinued temporarily, as the close of the exposition necessitated moving the laboratories. Work on the Thiogen process was started again in January, 1916, in the laboratories of the new mining experiment sta- tion at Berkeley, Cal., and was continued during the spring of 1916 until a point was reached where it was felt that the essential parts of the process had been carefully covered, and that some definite state- ments concerning the technical features and possibilities of the process, as given in this report, were warranted.

Jan 1, 1917

By A. L. Murray, C. A. Allen

"In the Spring of 1919, the Industrial Commission of Utah undertook the assembling of safety orders covering metal mining operations Just at that time there appeared several articles in the mining papers advocating the licensing of hoisting engineers, so this subject was given careful consideration,The licensing of hoisting engineers means that they must pass an examination covering the mechanical features of hoists and boilers, and must have a certain amount of experience. This undoubtedly serves to get a class of hoisting engineers that are better informed about the mechanical operation and theoretical considerations in hoisting and the only room for argument against it is that it is difficult to give an examination that will determine whether or not a man is a competent hoisting engineer.A man might pass an excellent examination yet be absolutely unqualified to operate a hoist and the judgment of the mine super- intelligent would have to be depended upon to choose the right man from among those who were licensed. This difficulty of properly determining, by ordinary examination, a man's qualifications to run a hoist caused the idea of licensing' in the ordinary sense of the word to be abandoned; but, as there was no question that a hoisting engineer should be physically fit, it was decided to require a medical examination, and at the same time to require the hoist engineer to state his experience, so the State would better knowledge of his general qualifications.The orders covering the question were therefore issued as follows;"

Jan 1, 1920

By J. F. Barkley

During the present war emergency, under the urge of the Federal Government to store coal, the following questions are frequently asked by coal users: (a) Will the coal lose any, of its heating value in storage? (b) Will it slack and give a smaller-size coal? (c) Will its burning characteristics change in any way? (d) Will it catch fire from spontaneous combustion? (e) What precautions should be taken when coal is stored? DISCUSSION (a) Loss of Heating Value Studies by the Bureau of Mines show that the loss of heating value of coal in storage commonly has been overestimated. Various types of storage tests were made on New River, Pocahontas, Pittsburgh gas, and Sheridan (Wyo.) coals. The following is quoted from Bureau of Mines Bulletin 136, Deterioration in the Heating Value of Coal During Storage, by H. C. Porter and F. K. Ovitz (p. 8):

Jan 1, 1943

By Wilder D. Foster

In estimating the hazardous qualities of a dusty atmosphere it is frequently desirable to determine the composition of the air-borne dust. Samples collected from ledges or from the rock itself are likely to be unsatisfactory for this purpose owing to the possibilities of differential disintegration of the rock and of variations in settling rates of the different components of the minerals. It may be necessary, therefore, to collect samples of dust from the air. Samples collected from the air may be analyzed chemically, by X-ray diffraction, and by the petrogrephic microscope. Chemical methods are unsatisfactory owing to the small samples usually available and to the limitations and complexities of present methods. X-ray technique requires expensive apparatus not ordinarily available except in research laboratories. Owing to the simplicity and rapidity of petrographic examination of atmospheric mineral dusts, it was considered worthy of further study.

Jan 1, 1938

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Jan 1, 2012

By Wilder D. Foster

In estimating the hazardous qualities of a dusty atmosphere it is frequently desirable to determine the composition of the air-borne dust. Samples collected from ledges or from the rock itself are Likely to be unsatisfactory for this purpose owing to the possibilities of differential disintegration of the rock and of variations in settling rates of the different components of the minerals. It may be necessary, therefore, to collect samples of dust from the air. Samples collected from the air may be analyzed chemically, by X-ray diffraction, and by the petrographic microscope. Chemical methods are unsatisfactory owing to the small samples usually available and to the limitations and complexities of: present methods. X-ray technique requires expensive apparatus not ordinarily available except in research laboratories. Owing to the simplicity and rapidity of petrographic is examination of atmospheric mineral dusts, it was considered worthy of further study.

Jan 1, 1938

By U. E. Brown

This papery describing the mining methods employed by the Bunker Hill and Sullivan Mining and Concentrating Co. at Kellogg, Idaho, is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the United States. The Bunker Hill and Sullivan mines are situated in the western part of the Coeur d'Alene district at Kellogg, Shoshone County, Idaho. The mines were discovered during the summer of 1885 and except for two short periods of labor trouble, between 1890 and 1900, have been in continuous operation. About 575 men are employed at the mine. The production is about 1,400 tons of lead-silver ore per day. This is treated in the company's concentrator and smelter at Kellogg.

Jan 1, 1931

By H. W. Wainwright

One phase of the research and development work on synthetic liquid fuels conducted by the Bureau of Mines at Morgantown, W. Va. in cooperation with West Virginia University deals with the purification of synthesis gas.2/ Most of the experimental studies on gas purification have been directed toward the removal of organic sulfur from gas, either catalytically or by adsorption with activated carbon. An important part of the purification program has been the development of suitable analytical methods for determining organic sulfur compounds. As the total sulfur content, organic and inorganic, of purified synthesis gas should not exceed 0.1 grain per 100 cubic feet, the need for accurate analytical methods is apparent. It is also apparent that such methods must be rapid if one wishes to evaluate various processes for removing sulfur from gas. The organic sulfur found in most gas produced from coal is usually present as carbon disulfide, carbon oxysulfide, methyl and ethyl mercaptans, and thiophene, with the exception of thiophene, the remaining organic sulfur compounds respond similarly to catalytic treatment and can be removed effectively. Not only does thiophene resist most catalytic treatment, but it poisons some catalysts, rendering them ineffective in removing the other forms of organic sulfur.

Jan 1, 1950

By Seth C. Schaefer

As part of the Bureau of Mines, U.S. Department of the Interior, effort to provide thermodynamic data for the advancement of minerals technology, the Gibbs energy of formation of sphalerite (zinc sulfide) was investigated with a high-temperature galvanic cell employing stabilized zirconia as the electrolyte. In the temperature range 948 to 1,210 K, potential measurements were obtained for the cell Pt, ZnS + ZnO, S02 = 1 atm // Zr02 // Cu20 + Cu, Pt, with the overall cell reaction ZnS(c) + 3 Cu20(c) = ZnO(c) + 6 Cu(c) + S02(g). (1) These results, combined with the best available values of ?Gf° for ZnO, S02, and Cu20 from the literature, give the Gibbs energy of formation of zinc sulfide for the reaction Zn(l,v) + 1/2 S2(g) = ZnS© (2) ?Gf° = -64.223 + 24.02 X 10-3T ± 0.650 kcal/mole (3) (948-1,180 K; standard states - pure liquid zinc and S2 gas at 1 atm), and ?Gf° = -92.720 + 48.17 X 10-3 ± 0.650 kcal/mole (1,180-1,210 K; standard states - pure zinc vapor and S2 gas at 1 atm). A third law analysis yields for the formation reaction Zn(1) + 1/2 S2(g) = ZnS(c), (5) a standard enthalpy of formation as follows: ?Hf298.15 = -63.64 ± 0.700 kcal/mole.

Jan 1, 1978

By K. O. Bennington

[Thermodynamic properties of two amphibole asbestos minerals were determined by the Bureau of Mines. The enthalpies of formation were determined by the hydrofluoric acid solution calorimetry method. Heat capacity measurements were made with an adiabatic calorimeter over the range of 5 to 315 K. High-temperature enthalpies above 298 K were determined with a copper-block drop calorimeter to 852 K for amosite and to 902 K for crocidolite. Thermodynamic data determined for amosite of the composition Fe5+2.2766Mg1.5209 Fe+03.12Mn0.0825) Si7.9163Al0.0837022.0363)(OH)1.9637 are: S°298 = 168.8 ± 5 cal/deg-mole; ?Hf°298-15 (elements) = -2419.24 ± 2.95 kcal/mole; ?Hf298.15 (oxides) = -30.92 ± 2.47 kcal/mole; and ?Gf° -2260.1 kcal. Corresponding data found for s3 ,1s = crocidolite of the composition (Na1.9Ca0.1)(Fe2+.024Fe2.5 01Mg0.475) (Si7.9713024Fe+2 2.501Mg0.475) (Si7.971 Al0.029022.095) (OH)1.905 are: S2.98-15 - 161.1 ± 4 cal/deg-mole; ?Rf° 2 298.15 (elements) = -2433.56 ± 2.99 kcal/mole, 10298.1s (oxides) = -87.69 1.70 kcal/mole, and ?Gf°298.15 = -2269.8 kcal.] Calorimetric values from this investigation were combined with other data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of the measurements. Tables of enthalpies of formation and Gibbs energies of formation are given as a function of temperature both from the elements and the constituent oxides.

Jan 1, 1978

Analyze variably saturated flow in mining and other environmentally sensitive settings through the use of personal computer (PC) based software. The Problem There is an increasing need for mining companies to quantify water contaminants and their migration in the unsaturated zone. New and innovative computer models are therefore necessary to more accurately assess the potential impact of mining activities on groundwater resources and the environment. Applications for unsaturated flow modeling include (1) assessment of the impact of surface or underground extraction mining on flow conditions; (2) assessment of various hydrologic designs for resource recovery, such as in heap leaching or in situ leach mining; (3) assessment of the transport of conservative nonrcactive constituents in response to migration from spoil piles, or acid mine drainage; and (4) assessment of any combination of the above to facilitate expeditious permitting for mining operations. Since the mid 1970's there has been a proliferation of mathematical models and procedures for solving unsaturated now problems; however, few of these approaches have been integrated into software for public use. Commercially available unsaturated flow software models typically are limited to a single application and have restricted approaches. For example, computer codes that solve the unsaturated flow problem based on an analytic expression arc restricted to a simple geometric shape, homogeneous and isotropic materials, and provide only information regarding pressure and flow conditions in specified wells. The variably saturated computer codes that take advantage of the finite difference or finite element approach arc often restricted to either steady state or transient solutions; utilize one specific moisture-retention relationship and moisture-dependent permeability function; do not account for hysteresis; and are used with specific hardware such as a mainframe or work station. This restricts their use because they arc hard to interface, and arc often poorly documented, support dependent, and expensive. The mining community needs a flexible, more broadly based, variably saturated fluid flow simulator for the PC-platform to more accurately predict fluid movement in the mining environment.

Jan 1, 1991

By L. B. Pankratz

Low-temperature heat capacities, high-temperature enthalpy increments, and the enthalpy of formation at 298° K were determined calorimetrically for vanadium subnitride (VN0.465). The low-temperature investigation gave S°298.15 = 6.379 ±0.005 cal/deg mole, and a combustion calorimeter investiga¬tion provided ?Hf°298.15 = -31.80 ±0.60 kcal/mole. The two quantities were combined with the high-temperature data to give standard values of enthalpies of formation and free energies of formation above 298° K. These and related thermodynamic functions were tabulated to 1,800° K. Similar data are included in the range of 298° to 1,600° K for the mononitride, VN.

Jan 1, 1971

By L. E. Schultze

The Bureau of Mines devised a technique to recover a Zn-Pb concen-trate from a geothermal brine. More than 99 pct of the Zn and Ph was precipitated by treating the brine with H2S and controlling the pH with lime. Recycle of the sulfide precipitates increased crystal size and resulted in easily filterable products. A typical sulfide precipitate contained 53 pct ZnS, 8 pet PbS, 24 pct MnS, and 15 pct FeS. Addition of sulfide as FeS or CaS was not effective in precipitating Zn and Pb, but Zn in the brine was selectively removed with a strongly basic ion-exchange resin. A proposed flowsheet for metals recovery is discussed.

Jan 1, 1985

By John D. Corrick

The environmental and nutritional characteristics necessary for maximum copper extraction from a low-grade ore by Ferrobacillus ferrooxidans have been explored as have many of the limiting parameters. Criteria considered were oxygen consumption, copper extracted, soluble copper concentration, temperature, pH, particle size, nutrients, and other inorganic salt concentrations. A set of environmental and nutritional conditions were developed for E. ferrooxidans Which supported cell reproduction and maximum microbial oxidation of a low-grade copper sulfide ore. Percolator tests conducted under these optimum conditions resulted in an 18 percent increase in the quantity of copper microbially extracted over that extracted under conditions considered to be standard. Manometric tests determined those extremes of environmental conditions and nutritional factors Which were detrimental to the extraction of copper by E. ferrooxidans.

Jan 1, 1965

By G. R. Palmer

Preliminary studies by the Bureau of Mines were conducted to determine the feasibility of a multiple-compartment, ion-exchange (MCIX) column simulator for examining the effect of multiple-orifice plates in the column. A rectangular, five-orifice, three-compartment, MCIX simulator with a cross-sectional plate area of 0.66 ft2 was used for the investigation. Orifices with open areas of 1, 3, and 5 percent were used with various operating conditions. The study was separated into three separate sections: (1) solution flow effect, (2) fluidization effect, and (3) resin transfer effect. The solution flow and fluidization studies showed that for solution flow rates of about 3 gpm/ft2, a I-percent open area plate functioned best, while at solution flow rates of 9 and 15 gpm/ft2, the best open areas were 3 and 5 percent, respectively.

Jan 1, 1981