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By C. O. Ruud, R. E. Siemens, D. Chandra

The mineralogical constitution of a lateritic ore dictates the type of metallurgical process that can be used to extract valuable metals such as nickel and cobalt . To provide needed mineralogical information on the interrelationships of the metals contained in domestic laterites , the Bureau of Mines awarded a grant to Denver Research Institute to study the transition - type , low - grade laterites found in northern California and southern Oregon . For comparison , limonitic - type laterites from New Caledonia and the Philippines were also studied . X-ray diffraction , electron microscopy , electron beam analysis , and conventional petrography were used to determine the mineralogical associations of nickel and cobalt in the laterites . Results showed that for both laterite types studied most of the nickel and minor amounts of cobalt are associated with the mineral geothite ( FeO ( OH ) ) . Most of the cobalt and minor amounts of nickel are associated with a mixed manganese oxide (wad ) mineral .

Jan 1, 1983

By Alvin Kaufman

Geothermal plants are competitive with conventional units. A geothermal plant can produce electric energy for 6.70 mills per kwhr, compared with 6.96 mills for coal, 6.74 mills for oil, and 7.04 mills for gas. These costs include fixed and variable charges. Potential for geothermal power exists in the Western United States, Alaska, and possibly Hawaii. Assuming that the current downward trend in cost per kilowatt of coal will cease and that the relative cost of gas and oil, already trending upward, may rise considerably more, geothermal energy will be utilized where available, in producing electric energy. It will be used in California first because it is directly competitive with gas-and oil-fired installations there. A long-term appraisal is difficult because little is known about the sources of geothermal power and the electric generating capacity which the steam fields will support. However, a market for geothermal steam-generated electricity exists within the Western States.

Jan 1, 1964

By Alvin Kaufman

Geothermal plants are competitive with conventional units. A geothermal plant can produce electric energy for 6.70 mills per kwhr, compared with 6.96 mills for coal, 6.74 mills for oil, and 7.04 mills for gas. These costs include fixed and variable charges. Potential for geothermal power exists in the Western United States, Alaska, and possibly Hawaii. Assuming that the current downward trend in cost per kilowatt of coal will cease and that the relative cost of gas and oil, already trending upward, may rise considerably more, geothermal energy will be utilized where available, in producing electric energy. It will be used in California first because it is directly competitive with gas-and oil-fired installations there. A long-term appraisal is difficult because little is known about the sources of geothermal power and the electric generating capacity which the steam fields will support. However, a market for geothermal steam-generated electricity exists within the Western States.

Jan 1, 1964

By David C. Oyler

The U.S. Bureau of Mines and the United States Steel Corporation evaluated the progress of methane drainage at the Oak Grove, AL, degasification pattern. Coalbed pressures were monitored between December 1981 and November 1985. Formation pressures, in the lower bench of the Mary Lee Coalbed, were reduced from 400 lbf/in2(ga) in 1977 to 50 lbf/in2(ga) in November 1985. Gas contents of coal cores obtained from monitor wells were compared with coalbed gas contents measured in 1976. Data indicated a 48- to 56-pct reduction within the pattern and a 29-pct reduction at a point 500 ft outside the pattern. The effect of the advance of a section of the Oak Grove Mine on changes in gas and water production rates in the pattern was evaluated. Gas production increases were noted in 12 wells; water production decreases were noted in 6. The times of initial influence indicate the presence of a zone of high permeability within the pattern. This zone correlates well in orientation and location with a fracture zone mined through at the mine. The existence of such fracture zones could have a significant effect on productivity of individual coalbed methane wells.

Jan 1, 1989

By R. V. Ramani, R. Bhaskar

"The spatial distribution of airborne dusts, deposition of dust in the airway, as well as the effect of airflow velocity and particle density on dust behavior in mine airways were studied in a set of experiments performed in a mine airway under controlled conditions. Considerable deposition of dust near the source was indicated. Pronounced effects due to velocity were observed in ambient dust concentration and deposition along the mine airway, both in the respirable and the total size ranges. Cross-sectional concentration measurements indicate an increase in concentration from the roof to the floor. The average cross-sectional concentration is about 75% of the concentration in the center of the airway.IntroductionA number of studies have been performed since the early 1950s on the behavior of dust in mine air (Bradshaw and Godbert, 1954; Dawes and Slack, 1954; Bradshaw et al., 1954; Hall, 1955-56; Reinhardt, 1971; Ford, 1971; Courtney et al., 1982). While the experimental data available from these studies are indeed useful in understanding dust cloud behavior in a specific situation, no generalized conclusions can be drawn because of the lack of data on parameters such as flow velocity, size distribution of the source dust, and particle density. These change from mine to mine or even within the same mine. The present study is aimed at providing a better understanding of the temporal and spatial behavior of dust particles in underground mine airways (National Academy ofSciences, 1980). The characteristics studied encompassed airborne concentrations and floor depositions over the entire size range as well as the respirable size range. The experimental results in this paper are intended to complement a mathematical model developed to predict ambient concentration and deposition of airborne dust in mine airways (Bhaskar and Ramani, 1986)."

Mar 1, 1989

By Danqing Xu, A. W. Khair

"This paper presents a laboratory simulation of regrinding and resulting dust generation. An Automated Rotary Coal Cutting Simulator (ARCCS) was modified to conduct regrinding experiment. In order to estimate the effects of coal properties and operating parameters on regrinding and dust generation, an orthogonal fractional factorial experimental design was implemented in regrinding experiment. Marple personal cascade impactors, Series 290, were used to measure dust concentration during experiment. Three types of coal seams, namely, Waynesburg, Pittsburgh, and Lower Kittanning, were used to represent different coal properties. Experimental results and complete parametric analysis were presented.In a rotary cutting system, all the broken coal and part of the remaining coal from previous cutting cycles must be transported through part or entire circumference of the cutting drum. This transportation of already recovered coal through the cutting zone of rotary head makes it a rotary grinder. Some of the coal particles will be subjected to secondary fragmentation or regrinding in the process. The potential effect on dust generation by regrinding is significant because the cutting head utilizes kinetic energy to comminute recov¬ered coal material. The moving bits and bit blocks on the cutting head impact coal particles and transfer some of their kinetic energy to the particles. After obtaining kinetic energy, coal particles are free to impact one another and they also impact the coal seam or cutting head. During impact, high impact force and high internal stress concentration are created in the particles. Kinetic energy is transformed into strain energy. When stored strain energy exceeds allowable strain energy, the particles will break. A great amount of respirable dust will be generated due to impact failure. In reality, regrinding occurs at the same time as primary cutting. The particles to be ground are the result of primary cutting. Both primary cutting and regrinding produce dust. Therefore, it is impossible to separate regrinding from primary cutting. In order to study respirable dust generation by regrinding and analyze the influencing parameters, a laboratory approach was adopted. In this approach, it is possible to study the regrinding separating from primary cutting."

Mar 1, 1992

By D. A. Reynolds, J. D. Davis

During early development of the blast furnace, Connellsville coke made entirely from Pittsburgh-bed coal proved to be an excellent fuel. The need for blending coking coals arose as the industry grew and it became necessary to carbonize coals having voking properties inferior to those of Pittsburgh coal Most coals carbonized today in continental Europe and this country are blonded: This practise has improved the quality of coke and permitted the utilization of coals that would yield inferior coke, if carbonized sepa- rately, The depletion of the world's better coking coals, which has been noted by leading coal technologists,2/4/wes accelerated during the recent war and. It is important, therefore, that reserves be evaluated and conserved. In the principal, steel-producing sections of this country, Pocahontas coals have been blended so extensively that the terms "low-volatile coking coal": and. "Pocahontas" have become virtually synonymous. Other low-volatile coals. have been used to manufacture metallurgical coke and will be used more extensively as, the supply of the better known and more accessible Pocahontas coals decreases. Recognizing the need for augmenting the supply of high-rank coking coals, the Bureau of Mines has included both low- and medium-volatile coals in its Survey of the Carbonizing Properties of American Coals, which was started with the cooperation of the American Gas Association in 1929. Twenty coals, 12 of low-volatile and 8 of medium-volatile rank, have been blended with high-volatile A Pittsburgh-bed coal, and five standard low- volatile coals have been blended with various high-volatile coals. Most of the results of carbonization tests of these coals and their blends have been

May 1, 1946

By P. J. Coleman

Research in the field of mining safety and health in the United States plays an important part in protecting the lives of miners. The National Institute for Occupational Safety and Health (NIOSH) Mining Program conducts surveillance, studies and developmental work aimed at improving the safety and health of miners. With recent reviews of the Mining Program by the National Academy of Sciences and the Mining Program response (NIOSH, 2008), the importance of setting goals, conducting high quality engineering and scientific research and evaluating the outputs, outcomes, relevance and impacts of these projects has been reemphasized. Surveillance of reported injuries is a first step in deciding on research directions and in designing specific projects. Groups of injuries often share features and attributes that suggest common causes and may respond to similar preventive efforts. Identifying groups of injuries also serves to prioritize intervention efforts. The Mine Safety and Health Administration (MSHA) Accident and Injury database (MSHA, 2008) provides individual case reports of mining injuries, illnesses and certain no-injury accidents (events such as roof falls that stop mine production or miners? activities for more than one hour). This database is an indispensable resource for researchers and stakeholders needing information on the statistics of these events. From an epidemiological perspective, research projects target groups of miners at risk due to specific patterns of work, equipment, mine settings and the management of safety and health in their mines. Incidence rates are provided by the MSHA data for selected variables, such as surface/underground location, standard industrial classification and state. While incidence rates are the preferred measure for all variables, denominators are not typically available; for example, to more clearly under-stand the data about injury by occupational type, it would be necessary to conduct demographic surveys. A current survey of the demographics of the mining industry should be complete by 2010, which will allow incidence rates to be developed for a number of variables such as age, occupation and experience. This survey will provide the first update of its kind since the first survey was conducted in 1985.

Jan 1, 2010

By Margaret R. Egan

The U.S. Bureau of Mines conducted experiments in the intermediate-scale fire tunnel to assess the influence of air velocity on the gas production and smoke characteristics during smoldering and flaming combustion of Pittsburgh seam coal and its impact on the detection of the combustion products. On-line determinations of mass and number of smoke particles, light transmission, and various gas concentrations were made. From these experimental values, generation rates, heat-release rates, production constants, particle sizes, obscuration rates, and optical densities were calculated. Ventilation has a direct effect on fire detection and development. The results indicate that, in general, increased air velocity lengthened the onset of smoke and flaming ignition, increased the fire intensity, but decreased the gas and smoke concentrations. Increased air velocity also lengthened the response times of all the fire sensors tested. Rapid and reliable detector response at this most crucial stage of fire development can increase the possibility that appropriate miner response (fire suppression tactics or evacuation) can be completed before toxic smoke spreads throughout the mine.

Jan 1, 2010

By J. E. Tiffany

Some of the gases produced by permissible explosives on detonation are poisonous, and the probable hazard involved by the inhalation of carbon monoxide in the past has been evaluated from results of tests in the Bichel Gage. Tests have now been made in the Experimental Coal Mine of the Bureau of Mines at Bruceton, Pa., to determine the composition of the gases obtained under actual mining conditions for the purpose of comparing these, results with those found by the Bichel gage tests. Two permissible explosives were procured for these tests, one that produces a relatively low quantity of poisonous gases in the Bichel gage (24.8 liters per 1-1/2 pounds of explosive) and another that produces a relatively high quantity of poisonous gases (94.6 liters per 1-1/2 pounds). The first of these is designated by the Bureau of Mines as a class A4/ explosive and the other is designated a class B explosive. In comparison with Bichel-gage tests, the shooting of permissible explosives in a coal shot hole resulted in a large reduction in the quantity of carbon monoxide, the principal poisonous gas, which; in the mine tests, was only 22 percent of that found in Bichel-gage tests: The quantity of carbon monoxide from the class B explosive in Bichel-gage tests was 3.8 times larger than that from the class A explosive; in the coalmine tests the ratio was 4:1. The concentrations of carbon monoxide in the mine tests, as determined by analysis of the atmosphere in an enclosed space resulting from shooting 1-1/2-pound and 3-pound charges of the class A explosive, were 0.03 and 0.06 percent, respectively, and the concentrations from 1-1/2-pound and 3-pound charges of the class B explosive were 0.10 and 0.24 percent.

Jan 1, 1950

By S. J. Gasior

Pilot plant studies showed the technical feasibility of fluidized-bed operation for producing hydrogen and synthesis gas by the steam-iron process. A mixture of iron and iron oxide from 20-to 100-mesh was partially reduced with a simulated producer gas and then oxidized with steam and/or carbon dioxide. Results of tests show the effects of pressure, temperature, bed height, gas-to-solids ratio, type of iron oxide, and composition of gas on the gas and solids conversions during reduction and oxidation. A baffled free-fall solids system was also found operable. The short residence time of about 5 seconds limited conversion of the solids.

Jan 1, 1961

"When a metal-mining company takes out a workmen's compensation insurance policy, it does so to relieve itself of its uncertain and variable financial liability under laps requiring payment to employees for lost-time accidents, there-by passing the liability or to the insuring agency. For this service, or rather for the assumption of the risk, the insuring agency charges the mining company a price, or in insurance parlance, ""a premium"".The insuring agency depends upon a volume and variety of business to average the losses incurred by its individual policy holders, and determines its price to cover losses that are suffered and its cost of doing business.It is generally known that all types of insurance are founded on the theory of probability applied to large groups of risks, Workmen's compensation insurance is no exception, and the average price paid therefor must be based on the frequency and severity of accidents in the particular industry or branch of industry under consideration. The frequency and severity rates are determined by statistics, which, of course, unless standardized, kept carefully and consistently, and analyzed properly, are liable to be inaccurate and misleadingThe importance of large groups in arriving at an average price for insurance service can not be overestimated, For example the writer knows of one small group of some twenty metal-mining companies whose losses during the past two years exceeded their premium charge by 54%. Not a single individual company during the two years kept its losses below the premium rate. For several years the group as a whole has persistently exceeded its premium rate, Such risks are not profitable to the insuring agencies and can only be carried where a large volume of good risks will balance the poor risks, but in order to conform to good insurance ethics the premium rate must be based on averages for the industry as a whole, and kept sufficiently low to induce operators to sell their risks."

May 1, 1924

By W. H. Oppelt

To provide a relatively structurally stable form of dried lump lignite, two North Dakota lignites from Mercer County were dried by the Fleissner process in an atmosphere of saturated steam at 200, 300, and 370 p.s.i.a. pressure, corresponding to steam temperatures of 382°, 417°, and 437° F., respectively. Two series of experiments were made at each test pressure with the individual lignites. In one series, the autoclave was preheated to the processing temperature before charging the lignite; in the other the lignite was charged into the autoclave at room temperature. In each case, heat losses were determined by blank tests of steam consumption over a similar operating cycle with the empty autoclave. The degree of moisture removal and net steam consumption were calculated from material balances. The amount of water removed as a liquid from the two North Dakota lignites during the heating and steaming periods was compared with results calculated from previously published data on drying Austrian lignite and Australian brown coal. These lignites, covering a wide geographical area, had original moisture contents ranging from 35 to 49 percent. The Austrian lignite and Australian brown coal are considered to be of Miocene Age, and the Dakota lignites belong to the Paleocene.

Jan 1, 1955

By Frank E. Cash

Accident prevention is an integral part of the operating procedure of the petroleum industry, and refinery officials and employees throughout the United States are exerting concerted effort to reduce the frequency and severity of accidents and are realizing definite results. In other words, the petroleum industry is safety conscious to a much creator decree than most of the other mineral industries. On January l, 1936, there were 11 operating, refineries in Louisiana with a crude-oil capacity of 199,750 barrels per day.4/ This report deals with safety in four of these refineries representing. 72 percent of the refinery capacity of Louisiana.

Jan 1, 1940

By J. F. Barkley

Two major problems in the operation of air preheaters for boilers are corrosion and the accumulation of deposits on the heating surfaces. Corrosion or loss of metal necessitates replacement of parts; the accumulation of deposits decreases the size of the gas and air passages, resulting in increased pressure drop for the same gas flow, and also affects the heat transfer. These items, either singly or together, limit the capacity and efficiency at which the equipment can be operated and affect its availability, even causing undesirable shutdowns under extreme conditions The field and laboratory work on regenerative air preheaters described in this report covers research on the relative corrosion resistance of different materials, such as various metals, special metal coverings, and fired clays, and studies on deposits, their nature, analyses, and corrosive effects. This is the first report on cooperative work of The Air Preheater Corp., of New York City, and the Federal Bureau of Mines.

Jan 1, 1953

By Lindsay D. Norman

Four chloride and seven fixed-nitrogen processes for recovering manganese from domestic resources are described. The chloride processes are divided into two classes (leaching and chloridization) depending upon the major operation responsible for converting the manganese minerals to the chloride from which manganese oxide products are obtained. The fixed nitrogen processes, all of which yield high-grade manganese oxide products, are essentially either leaching or roasting processes. The 11 processes include HC1 leach, HC1 chloridization, HC1 chloride volatilization, CaC12 chloride volatilization, NO2 leach, HNO3 leach, HNO3 ?NO2 leach, H3 ?CO2-H2O system leach, (NH4)2SO4 leach, (NH4)2SO4 roast , and ammonium salt roast .

Jan 1, 1963

By Lindsay D. Norman

Four chloride and seven fixed-nitrogen processes for recovering manganese from domestic resources are described. The chloride processes are divided into two classes (leaching and chloridization) depending upon the major operation responsible for converting the manganese minerals to the chloride from which manganese oxide products are obtained. The fixed nitrogen processes, all of which yield high-grade manganese oxide products, are essentially either leaching or roasting processes. The 11 processes include HC1 leach, HC1 chloridization, HC1 chloride volatilization, CaC12 chloride volatilization, NO2 leach, HNO3-NO2 leach, NH3-CO2-H2O system leach, (NH4)2SO4 leach, (NH4)2SO4 roast, and ammonium salt roast.

Jan 1, 1963

By K. J. Miller

A two-stage froth flotation technique was developed in the laboratory to separate fine-size pyrite from coal. The process consists of the initial flotation of a 15-percent solids coal slurry with a minimum of frother; the coarse, free pyrite and other refuse are removed in the tailings. The froth product from this first stage is then repulped and treated with a coal depressant, a pyrite promoter, and a frother to float the remaining fine-size pyrite or pyrite attached to coal particles. With the two-stage process, the pyritic sulfur content of a Lower Freeport bed coal sample was reduced from 1.78 percent to 0.75 percent in the first stage, and from 0.75 percent to 0.27 percent in the second stage with good clean coal recovery.

Jan 1, 1972

By W. W. Weller

Heat capacities of ferrous molybdate (FeMoO4) and ferrous tungstate (FeWO4) were measured over the temperature range 51° to 298.15° K. Ferrous tungstate has a lambda type heat capacity anomaly at 74° K. The 298.15° K entropies are FeMoO4) 30.9 cal/deg mole and FeW04) 31.5 cal/deg mole.

Jan 1, 1966

By M. G. Zabetakis

At ordinary temperatures and pressures methyl ethyl ketone (MEK)-air mixtures containing between 2.0 and 11 vol.-pct. MEK and methyl isobutyl ketone (MIBK)-air mixtures containing between 1.5 and 7.5 vol.-pct. MIBK are flammable. However, MEK-bromochloromethane (BCM)-air mixtures containing at least 6.2 vol.-pct. BCM and MIBK-BCM-air mixtures containing at least 7.0 vol.-pct. BCM are nonflammable. Also, MEK-BCM-air and MIBK-BCM-air mixtures containing less than 18.7 vol.-pct. oxygen are nonflammable. To assure the formation of nonflammable mixtures when mixed with air, MEK-BCM vapor mixtures must contain at least 1.6 vol. BCM per volume MEK, and MIBK-BCM vapor mixtures must contain at least 2.8 vol. BCM per volume of MIBK; these quantities of BCM would be produced by liquid mixtures containing 55 vol.-pct. BCM in the first case and 60 vol.-pct. in the second. An MIBK-BCM-trimethylene chlorobromide mixture containing equal volumes of each liquid forms nonflammable mixtures with air at ordinary temperatures and pressures. The same is true of a liquid mixture containing 34.6 pct. (liquid volume) BCM, 34.b pct. perchloroethylene, 15.4 pct. MIBK, 7.7 pct. toluene, 3.85 pct. ethyl amyl ketone, and 3.85 pct. trimethylene bromide.

Jan 1, 1960