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By C. M. Frost

Crude shale oil produced by gas combustion retorting of Green River oil shale was hydrocracked over a cobalt molybdate catalyst at operating pressures of 500, 1,000, 1,500, and 3,000 psig, an operating temperature of 8900 F, and a liquid hourly space velocity of 1.0. Hydrogen feed rate was maintained at 6,000 scf/bbl. The volume-percent yields of total liquid product were directly proportional to the operating pressure. Weight-percent conversion and volume-percent yields of gasoline were directly proportional to the log of the operating pressure. Catalyst deposit percentages were inversely proportional to the log of the operating pressure. Nitrogen and sulfur removal rates as well as saturation of the liquid products increased as the operating pressure was increased.

Jan 1, 1973

To rapidly and dependably locate shorts and opens in mining equipment power cables. Approach: The approximate locations of faults are found using a sound pulse echo, then the faults are exactly located with one of two probes. How It Works: To approximately locate u fault in shielded or unshielded cable, the cable is disconnected from the mine power center, and connected to the sound pulse generator. The generator is also connected to the ground conductor of the cable. When the generator is energized, electrical pulses are transmitted, and each moves along the conductor until it reaches a fault. When a pulse reaches the fault an echo returns to the instrument, either a positive pulse if the fault is an open, or a negative pulse if the fault is a short. See Figure 1. The further along the cable the first fault is from the instrument, the longer it takes for the echo to return. The instrument automatically measures the time and calculates the distance. The distance in feet is shown on an illuminated digital display.

Jan 1, 1976

Compare the dust control efficiency and bit life of surface coal mine drills using standard water injection and water injection with water separation. Approach A research study was conducted to determine if a water separation technique affects wet suppression dust control. Dust control efficiency and bit life of surface coal mine drills were compared during tests using both standard water injection (wet drill bit cutting) and water injection with water separation (dry drill bit cutting). Background Surface coal mine blast hole drills typically generate a substantial amount of dust during the drilling cycle. One method used to control this dust is the injection of water into the bailing air. This is known as wet suppression.

Jan 1, 1988

By Thomas V. Falkie, R. Venkataramani

The empirical nature of this investigation required measurements of variables under operating conditions in underground coal mines. The variables to be measured were based on the postulated character¬istics of the loading function, as described in the previous chapter. One class of variables presumed to influence the loading function are geological variables. Accordingly, the sites for data collection were selected in different bituminous coal seams at dispersed locations in order that variation in geological conditions would exist. Seven mines in central and western Pennsylvania and one mine in northern West Virginia were selected as data collection sites. Five different coal seams were represented by these mines. The remaining classes of variables - geometric, mechanical, and procedural - were measured as they occurred in the mines. A description of the measurements, and the conversion of these measurements to forms which could be-analyzed for effect on the loading function is given. Mining Dimensions At the underground working face, the following dimensions were measured: a. Thickness of coal excavated. b. Thickness of shale excavated. c. Total height excavated. d. Width excavated. e. Depth of penetration of each machine cut. With the exception of the last of these dimensions, all were measured

Jan 1, 1972

By Andrew B. Cecala, Edward D. Thimons, George W. Klinowski

The U.S. Bureau of Mines has designed and evaluated total mill ventilation systems at two different mineral processing operations. Both systems have proven very effective at reducing respirable dust levels throughout the mill in a cost-effective manner. A 25,500-cfm system installed at a clay processing mill provided approximately 10 air changes per hour. This system reduced respirable dust concentrations by approximately 40 pct throughout the mill building. The second evaluation was performed at a silica sand operation. Tests were performed with 50,000 and 100,000 cfm of ventilation to the mill building, corresponding to 17 and 34 air changes per hour. Average mill-wide respirable dust reductions were 36and 64 pct, respectively. Not only did these systems reduce respirable dust concentrations and increase visibility throughout the mills, they were also easy to install and required minimal maintenance. A total mill ventilation system provides a general purging of the mill air; the system should be viewed as a supplemental technique to assist other dust control systems in operation.

Jan 1, 1993

By John C. Machisak

THIS CHAPTER reports employment data and injury experience in the metal, nonmetal, quarrying, sand and gravel, and slag (iron blast furnace) industries of the United States in 1959. Each industry is treated separately, and no attempt has been made to combine data to show an overall total for this group of mineral industries. The slag canvass is included for the first time (data on employment and injuries were not collected before 1958), and, like other canvasses included in this chapter, data are voluntary. Employment and injury experience for all mineral industries can be found in volume III. The employment and injury information in this chapter came from reports submitted to the Bureau of Mines before May 31, 1960; therefore, figures are preliminary and subject to revision. Voluntary reports submitted by operators have contributed substantially to safety promotion since 1911, when the Federal Bureau of Mines started collecting employment and injury facts.

Jan 1, 1960

By Fred N. Kissell

Methane-flow and pressure data taken from a mine in the Pocahontas No. 3 coalbed are compared with flow rates from lump coal obtained in laboratory experiments. From this, it is concluded that the main source of gas is the intact coalbed rather than a "crushed zone" near the working face. The permeability and sorption capacity of the intact coalbed are calculated and gas emission rates are theoretically accounted for.

Jan 1, 1972

By M. K. Larson, J. K. Whyatt, R. B. Langston, J. C. Johnson, H. Kirsten, T. M. Brady

An experiment is described in which hollow inclusion cells (HICells) were used to measure stress in a jointed rock mass during drift development at the Stillwater Mine, Nye, MT, USA. Two HICells were installed in the footwall approximately two drift widths ahead of the face. One HICell was over cored and then immediately tested in a biaxial chamber. The other HICell was left in place and monitored as the drift was excavated in three advances, each one-half the width of the drift. Strains were recorded hourly by a datalogger. Results show that there was little stress change during the first and second drift advances, but that a large stress change occurred after the third advance. The measurements also showed that the in situ principal stress directions lined up with regional geologic structures. Stress changes during face advance were likely caused by deformation along localized joint sets and inelastic deformation near the face.

By Fred N. Kissell, J. E. Matta, J. C. LaScola

The methane gas emitted from coal samples collected from the conveyor belts dumping into silos was measured by the Bureau of Mines. Approximately 50 pct of the total gas desorbed into a sealed can within 1 week was released during the first 24 hours. No simple correlation between the gassiness of the coal stored and the methane concentration in the silo open space above the coal was found. This was probably because the gassier coals were stored in open-top silos, which were better ventilated. Although the methane concentration in the open space above the coal pile was less than 1 pct for all 34 silos investigated, a methane measurement in the coal pile showed that high methane concentrations can exist. The methane released in the pile appears to accumulate and not liberate freely into the open space above the coal pile. Probably this gas is released during reclaiming operations, but further research is required to substantiate this claim.

Jan 1, 1978

By W. F. Marshall

The effect of engine parameters on exhaust emissions from two diesel engines was studied experimentally. Fuel-injection characteristics and intake air conditions were considered as parameters influencing the emissions. Emphasis was placed on the effect of parameter variations on nitrogen oxide (NOx) emissions, because diesels generally emit very low levels of carbon monoxide (CO) and unburned hydrocarbons. Emissions other than NOx were at lowest levels when the engines were adjusted for best performance. NOx emissions can be diminished somewhat through variation in fuel-injection characteristics, but there generally are penalties in emissions of CO, smoke, and unburned hydrocarbons or in engine performance. Temperature and composition of intake air have a significant effect on NOx emissions. Levels of NOx are reduced by recirculating the exhaust gas or by adding water to the intake air stream. However, the rate of water added or exhaust gas recirculated must be limited to prevent the degradation of engine performance and increased emissions of CO and smoke. At high exhaust recirculation rates, levels of CO and smoke were increased such that it was necessary to derate the engine and also to use a catalytic system for oxidation of CO.

Jan 1, 1971

Develop a machine which can accurately simulate both the breathing and metabolic functions of a human being. The advantages of such a machine over a human being for testing of respiratory protective devices lie in its ability to quantify metabolic input, its repeatability, and the lack of a need to deal with the vagaries of human subjects. Breathing simulation has been widely achieved throughout the world but metabolic simulation has not. Approach Utilize the latest computer technology and place the complex portion of the system in software, leaving the mechanical portion as simple as possible. How It Works The concept for the automated breathing and metabolic simulator (ABMS) was developed through a research contract with the Pennsylvania State University. The ABMS utilizes a continuous removal/replacement concept to simulate metabolic functions, with breathing and metabolic functions being controlled by a computer. The mechanical portion of the machine is simple; the complexity of the system lies in its computer software which is not subject to maintenance problems.

Jan 1, 1987

Minimize airborne respirable quartz dust produced by continous mining machines. Approach Install a shovel-mounted underboom water spray system on the off-curtain side of the mining machine. Dusty air containing quartz is momentarily trapped under the boom, where it is captured by fine spray mist. The remaining dust cloud is directed immediately behind the curtain before it can migrate back to the machine operator's location. How It Works Previous studies have shown that most of the dust generated by continous mining machines occurs under the boon as the cutter head shears down. The primary source of respirable quartz dust on many continous mining operations is cutting or trimming roof rock immediately prior to shearing. This results in very high concentration , of

Jan 1, 1989

By R. V. Lundquist

Past reports by the Bureau of Mines have described the extraction of alumina from numerous aluminum silicate materials by the lime-soda sinter process. The results from pilot-plant investigations of six materials, with alumina-to-silica mole ratios from 0.3 to 8.7, indicated a relationship between the alumina-silica ratios and the processing characteristics of the sinter. A series of laboratory tests was conducted to define this relationship. Sinter and leach tests determined that an alumina-to-silica mole ratio of 0.90 or greater resulted in the best alumina and soda recoveries while leaving the leach slurries practically free from any tendency toward gelation. The widely different chemical and mineralogic properties of the various aluminous materials used in compounding the mixes had no perceptible effect on the leaching characteristics of the sinter. The blending of low-cost, high-alumina materials with aluminum silicate materials to give an alumina-to-silica mole ratio of 0.90 or greater would improve alumina and soda extraction and minimize operating problems in the lime-soda sinter process.

Jan 1, 1970

By P. G. Barnard

Losses of alloying metals in furnace flue dusts, grinding swarfs, and mill scale produced during the manufacture of stainless steel are substantial. About 25 million lb Cr, 8.7 million lb Ni, and 150,000 lb Mo and other critical metals can be made available annually for recycling by a process developed by the Bureau of Mines. Stainless steel wastes pelletized with a portland cement binder were reduced in a small electric-arc furnace by a two-stage process to produce a recyclable alloy containing Cr, Ni, Mn, and Fe. The initial reduction was with carbon; the second, with ferrosilicon. Results are compared with previously reported laboratory induction melting tests. A 2,000-lb demonstration test of the process in a commercial electric-arc furnace is also described. Data are also presented on three 1,500-lb tests made using various slag conditions in the electric-arc furnace. Recoveries up to 99 pct of the Fe, Cr, and Ni contents of stainless steel wastes were obtained in using the process.

Jan 1, 1977

Minimize the risk of conveyor belt fires in underground coal mines by improving the accuracy of and means by which flammability data are acquired. Approach Develop a large, laboratory-scale flammability test for mine conveyor belting that realistically assesses its fire resistance. Background A conveyor belt fire in an underground coal mine is a serious threat to life and property. To minimize the risk of belt fires, the U.S. Code of Federal Regulations (CFR) for underground coal mines requires approved fire-resistant belting. Despite this precaution, about 25% of the reportable underground coal mine fires from 1983 through 1988 involved conveyor belting. In several instances, hundreds of feet of belting were destroyed. The current flammability test for fire-resistant belting is specified in 30 CFR, Part 18.65 and is conducted by (be Mine Safety and Health Administration (MSHA). The small-scale test is performed in a 21-in-cubical chamber with 6-in-long by 1/2-in-wide belt samples. To evaluate the flammability of conveyor belting under more realistic conditions, the U.S. Bureau of Mines conducted large-scale fire tests of belting. The large-scale data were then utilized in the development of an improved laboratory-scale flame test for fire-resistant belting.

Jan 1, 1991

By Charles L. Kimbell

This study is intended to serve three roles. First, it is the second annual edition of this study in a separate volume that represents a global overview and summary to supplement and complement the five regional volumes that now constitute the U.S. Bureau of Mines international, geographically arranged studies. In this regard, it also extends previous works under this title that appeared in the inter-national volume of the Minerals Year-book from the inception of that volume (the 1963 edition) until it was subdivided into six separate volumes in 1989. Following the traditional format of past chapters under this title, the basic statistical presentations herein deal chiefly with 1990, and in a few instances with 1988 or 1989; these latter two only because more recent, comprehensive global statistics simply are not yet available owing to delays in data collection and processing in some countries and continued governmental suppression of data in others. The second role of this study is to provide an update to the coverage of events impacting on the world's mineral industry that have occurred between the end of 1990 and the preparation of this study. Inclusion of this update is almost essential because of the potential effect of some of these events on global mineral industry activities.

Jan 1, 1993

By C. A. Herbert

"The Bureau of Mines for a number of years has conducted experiments at its experimental mine near Bruceton, Pennsylvania, on the explosibility of coal dust, with particular reference to dust explosions in coal mines, and the knowledge so rained may well be applied to the handling of coal dust at industrial plants and elsewhere.Powdered coal is coming into use more and more as a fuel, and the dangers incident to its use should be recognized and guarded against, as a number of accidents have occurred in recent years due to ignorance of this danger or to carelessness.Within the past three years two very serious accidents, under almost identical circumstances, have occurred on the surface at two different coal mines in Southeastern Iowa, due in each case to the sudden ignition of a cloud of fine coal dust.The first accident resulted in the burning of six men, three of them fatally; the second burned eleven; three men died as a result of their burns.The mines in the Southeastern part of Iowa, where these two disasters occurred, are operating in a thin coal bed averaging about three feet in thickness, and are worked on the long-wall advancing system similar to that of Northern Illinois.The miners in this section are paid on a screened coal basis; in other words, receive no pay for the fine coal. As a result they use forks in loading the coal into the mine cars, and naturally a considerable quantity of coal is left along the roadways. Subsequently this fine coal, together with the roof rock that is taken down to give sufficient height on the roadways, is loaded into cars and dumped in piles on the surface. This roof rock is a block, oily shale and the contribution of fine coal and oil shale gives ample combustible material to thoroughly burn the rock as it is dumped."

Jul 1, 1923

Reduce costs of surface mine reclamation by improving scaper operating efficiency and reducing tire costs. Approach The Wheel Slip Monitor senses and compares the peripheral speed of a scraper's four tires 10 the true ground speed of the scraper, and alerts the operator if any of the tires exceeds a predetermined amount of slip. This system helps scraper operators reduce wheel slip during the loading cycle, thereby improving the loading efficiency of the scaper and reducing tire wear and damage. How It Works The system consists of five ultrasonic doppler velocity-sensing devices for measuring the speed of each wheel as well as the true ground velocity (see photograph). Each sensor produces an electrical output signal having a frequency proportional to the speed of the tire or terrain. The signals are conveyed through electrical cables to a control box in the operator's cab where they are converted to voltages proportional to individual wheel speeds (see photograph). The signals are further processed to activate a blinking red light, corresponding to any individual wheel which is slipping, and to sound a beeping tone that is audible to the scraper operator. The rate at which the light blinks and the tone beeps is proportional to the degree of slip. Alerted, the operator can take corrective action.

Jan 1, 1985

By Jürgen F. PH. D. Brune, Alex C. Smith, Michael A. Trevits

Underground coal mine fires in the United States continue to present a significant hazard to the safety and health of mine workers. The leading causes of mine fires include flame cutting and welding operations, frictional heating and ignitions, electrical shorts, mobile equipment malfunctions, and spontaneous combustion The National Institute for Occupational Safety and Health (NIOSH) is conducting an in-depth program of research to address mine fire prevention, early and reliable fire detection and mine fire suppression and control technologies. One segment of the research portfolio is focused on remote methods for addressing coal mine fires. This research is important because remote methods represent the primary means of fighting a mine fire when conditions are too dangerous to fight the fire directly underground. Technologies under investigation include remote methods for installing ventilation control devices (mine fire seals) and remote methods for suppressing the fire using, the injection of inert gas, gas-enhanced foam and jet engine exhaust gases into the fire zone. This paper presents a summary of remote mine firefighting technologies used in the U.S. and the results of completed NIOSH research.

By A. G. Kim

Coal formation begins in peat swamps or bogs, in which microorganisms alter plant material and initiate the formation of carbonaceous sediments. Methane, which constitutes about 98 percent of the hydrocarbon gas in coalbeds, is known to be a product of anaerobic microbial metabolism. To determine if other hydrocarbon gases could be produced in an environment similar to that of a swamp, samples of wood cellulose and lignin were inoculated with soil micro-organisms and incubated anaerobically. The resultant gases included methane, ethylene, propane, propylene, butanes, pentanes, and carbon dioxide. Hydrogen was also produced from the wood samples during the first month of incubation. Over 90 percent of the produced gas was methane; C02 was the other predominant component. Concentrations of all other hydrocarbon gases ranged from l to 20 parts per million, approximately 0.1 percent of the total hydrocarbons, which was less than the concentration in coalbeds. Therefore, although higher hydrocarbons could be produced in a swamp environment, subsequent mechanisms, either concentration by adsorption or formation during geochemical reactions, must affect the final concentration of higher hydrocarbons in coalbeds.

Jan 1, 1972