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By Donald F. Reed

In its investigation of old, abandoned, lead-zinc mines at which records of operations are not available, in 1914 the Bureau of Mines dug surface trenches anti', in 1947 It diamond-drilled three holes at the Albright Farm deposit in Sinking Valley. Some good lead-zinc ore had been extracted from veins in dolomitic limestone during the time of the American Revolution and as late as 1870. Since that time the only activity was sporadic prospecting and developing. Thu Bureau of Mines disclosed two additional veins by surface trenching, but diamond drilling failed to find significant lead-zinc mineralization.

Jan 1, 1949

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

Mine ventilation can be broadly defined as the branch of mining engineering primarily concerned with the controlled flow of air through mine airways to maintain an acceptable atmospheric environment wherever men work or travel underground. Martinson (1976) has defined three elements of mine ventilation, 1) an engineering element concerned with establishing quality control (removal of dust and gases), quantity control (regula¬tion of air direction and magnitude) and climatic conditioning (temperature-humidity control), 2) a biological element in which an understanding of biological response is used in assessing the mine environment, and 3) a philosophical element requiring judgements as to the degree of risk or worker discomfort that is socially acceptable. Most texts on ventilation, such as Hartman (1961), limit themselves to a discussion of the engineering element. Although also limiting his text to engineering control, Weeks (1928) thoughtfully addresses the other elements in the preface of his book where he states: "Life is brief and happiness elusive under the best of conditions; so beside the commercial aspect must be placed the humanitarian. Is it not reasonable that the operator should give his men a chance to spend their working hours in a comfortable environment, with the danger of sudden death or disability reduced as much as possible?" The statutory requirements of ventilation are, in most countries, established on the basis of biological response as determined by basic research or are dictated by social awareness, often touched off by major disasters, resulting in demands on regulatory bodies for more stringent requirements. To a limited extent, the philosophical and biological elements of ventilation are intertwined in that social awareness may

Jan 1, 1977

By Carlton E. Brown

In 1935 , Brown and Yant / described a microprojector ( microscopic arrangement for projecting images on a screen ) for use in counting and measuring the size of dust particles in Owens - jet dust - counter and simila dry samples of dust collected from the air . In 1938 Brown and others , described a modification of this microprojector that could be used also in counting dust in impinger samples . Microprojectors of this second type have been set up by many mining companies and others and have been made commercially available . Hamly and Pullen5/ described a modification of this microprojector for use in making rapid comparative estimates on konimeter samples and other determinations . This report contains information on still another modification named the "midget microprojector " because of its small size .

Sep 1, 1944

Develop a safe, nonpolluting power source for underground mining equipment. Approach The Bureau of Mines and EIM-CO Mining Machinery International entered into a cost-shared project to develop and demonstrate a novel power source for mining. An underground mining utility truck was equipped with an ultra-low-emission hydrogen-fueled engine and a safe, metal hydride fuel storage system. How It Works The nonpolluting hydrogen engine and a "solid-state" (metal hyride) hydrogen fuel storage system were combined to power a utility mining vehicle. An 85 horsepower diesel engine was convened to burn hydrogen. The engine was converted by equipping it with a spark ignition, lowering the compression ratio, turbocharging, and adding an ahercooler and a parallel fuel induction system. Parallel induction provides two intake paths, one for hydrogen and one for air. It avoids intake-manifold backfiring by keeping the hydrogen and air separate until they enter the cylinder.

Jan 1, 1986

By Edward McHugh, Jami M. Girard, Stanley M. Miller

A computer analysis of bench stability has been developed to account for multiple occurrences of potential slope-failure modes in discontinuous rock masses. Bench-scale plane shears and tetrahedral wedges are simulated and stochastically analyzed to estimate the probability of retaining specified catch-bench widths. This geotechnical information is useful in designing bench configurations to improve pit-slope stability and help alleviate rockfall hazards.

By A. A. Giardini

This report represents the results of a literature study on boron nitride and related substances. The purpose of the study was to find Information that might be of value for production of a new, hard modification of boron nitride preferably in single crystal form. The report consists of a review of the major developments in boron nitride research, a discussion of the results, tabulations of physical and chemical properties;, conclusions drawn from the study, and a bibliography.

Jan 1, 1953

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

Comprehensive ventilation surveys are made to review the adequacy of the mine system with regard to both statutory requirements and/or company policy, to evaluate improvements to the current ventilation system and to plan for £stun expansion. If computer simulation is to be used for these purposes, accurate quantity and pressure measurements become an absolute necessity since the validity of the computer generated output is heavily dependent on the accuracy of the input data. Consequently ventilation surveys that are run to generate input data for computer simu¬lation must use the best data collection procedures to guarantee as accurate results as are possible. These requirements have led to modifications in procedures that are used for routine ventilation surveying. McElroy and Kingery (1957) have recommended that pressures be measured independent of quantities since minor changes in mine conditions have a greater effect on absolute pressure measurements than on quantity measure¬ments. They estimate that, for large mines, a pressure survey may take only 1 to 3 days while the corresponding quantity survey would require 1 to 3 weeks. Although this procedure would undoubtedly lead to more ac¬curate pressure measurements, its use for the development of computer input data is not recommended for the following reasons. Atkinson's equation, H = RQ2, is used in computer oriented analysis to develop the airway resistance, R, based on quantity and pressure loss measure¬ments. It can easily be seen that since R a 1/Q2 and R a H, the effect of errors in quantity measurement is, in fact, more significant than those in pressure measurement. If the quantity and pressure measure¬ments are made at different times another problem results. Minor changes in quantity that may occur in the time between the pressure and quantity

Jan 1, 1977

By William B. Harper

Domestic sales of carbon black sustained the upward movement for the 4th consecutive year, reflecting the increased sales of motor vehicles during the same period. Sales of carbon black in the domestic market topped 2 billion pounds for the first time during 1965 and have more than doubled the output of 20 years earlier. By far the largest user of carbon black is the rubber industry. That use accounted for more than 94 percent of the carbon black consumption with the bulk of it being used in tire casings and tubes. Thus demand for carbon black is naturally sensitive to trends in the sales of passenger cars and other motor vehicles, Manufacturers of inks, paints, plastics, paper chemicals, and food are also important users of carbon black.

Jan 1, 1967

By B. W. Gandrud

[The meaning of the term "bauxite' has always been somewhat vague and indefinite, and the term has been used in various applications to denote sometimes a rock, sometimes a mineral, but more frequently an ore. It seems logical to think of bauxite as an ore, however, because a very large part (probably at least 85 per cent) of the entire world's production of bauxite is at present being used as a source of aluminum and aluminum chemicals. In the United States there are two districts that, produce bauxite - the Arkansas district and the Alabama-Georgia-Tennessee-Mississippi district. The deposits in Mississippi have been discovered recently and are riot as yet productive but it seems reasonable to consider them as apart of the-district hat includes the deposits of Alabama, Georgia, and Tennessee. The, two districts are often referred to as the Arkansas field and the Appalachian field. Of these two the Arkansas field has been by far the largest producer, and at present over 90 per cent of the bauxite production of they United States comes from the Arkansas field. The bauxite industry in the Appalachian field had its beginning in 1889, and since that time the total production of the states of Alabama, Georgia, and Tennessee has been, nearly a million tons. The production of bauxite in this field has languished in the last five, or six, years, and In 1927 its production was only about 14,000 tons, according to Harder4. The recent decrease in production is due mainly to the fact that many .of the known deposits of commercial-grade ore have become exhausted. There are, however, considerable quantities of low-grade bauxite in the Appalachian field, but these have not been available because there has been no satisfactory way of concentrating low-grade bauxite. The quantity, of low-grade material in the Appalachian field is probably, fully as large as the tonnage of commercial ore which the field has already produced.]

Jan 1, 1928

By C. E. Brechtel

Cooperative research efforts by the Bureau of Mines and Agapito & Associates, Inc., Grand Junction, CO, used a one-dimensional, finite-element computer model to simulate turbulent mass transfer in face ventilation of oil shale mines. The objective was to study the dilution of methane released by rubbled oil shale during blasting. A methane release rate function was developed from the back-analysis of field measurements, and the finite-element model was calibrated using tracer gas characterization data from tests of full-scale face ventilation systems.

Jan 1, 1989

By R. O. Dannenberg

Applicability of the fluosilicate sintering process to recovering beryllium from beryl-spodumene concentrate analyzing 1.4 to 3.7 percent BeO (10 to 30 percent beryl) was investigated. The work was one phase of a Bureau of Mines research program undertaken to assess applicability of conventional processes and to devise new procedures for treating various potential beryllium feed materials. Beryllium recovery of about 70 percent in a product of 99-percent BeO grade was achieved in treating 3D-percent beryl concentrate. The process consisted of (1) sintering a briquetted charge of concentrate, soda ash, and sodium fluosilicate for 3 hours at 750° C.; (2) extracting the soluble beryllium by multiple stages of water leaching; (3) adding caustic to the leach solution and boiling to hydrolyze and precipitate crude beryllium hydroxide; (4) dissolving the crude beryllium hydroxide in sulfuric acid and separating the solution from undissolved silica; (5) sulfidizing the acid beryllium solution to precipitate heavy metal impurities; (6) adding ammonia to the clarified sulfate solution to precipitate beryllium hydroxide; and (7) converting the hydroxide to beryllium oxide (beryllia) by calcining at 900° C. About 60 percent more sodium fluoSilicate was required per unit of beryl than is used industrially in treating 10-to 12-percent BeO concentrate (80 to 90 percent beryl). Recovery decreased, and flux requirements increased, when treating concentrates containing less beryl.

Jan 1, 1963

By William C. Cooley

This volume contains copies of the 5 x 8 in. accession card file for all items collected which were judged to be relevant to underground hydraulic coal mining. In many cases, abstracts are included. Abstracts were taken from the source, from other reviews, or from the preliminary screening of Russian documents performed by Dr. A. L. Brichant. No attempt was made to write abstracts for every accession item.

Jan 1, 1975

By Rudolf E. Greuer, Linneas W. Laage, Xinton Chang

MFIRE is a computer simulation program that performs normal ventilation network planning calculations and dynamic transient-state simulation of ventilation networks under a variety of conditions The program is useful for the analysis of ventilation networks under the influence of natural ventilation, fans, fires, or any combination of these MFIRE simulates a mine's ventilation system and its response to altered ventilation parameters such as the development of new mine workings or changes in ventilation control structures, external influences (varying outside temperatures), and internal influences (fires) Extensive output enables detailed, quantitative analysis of the effects that the alteration will cause to the ventilation system The program was developed at Michigan Technological University (MTU), Houghton, MI, with support from the Bureau of Mines A personal computer (PC) version of the program was completed under contract for the Bureau by MTU The purpose of this report is to document the installation and use of the PC version of the program MFIRE

Jan 1, 1990

By Andrew Cecala

During a recent National Institute for Occupational Safety and Health field evaluation of a newly designed filtration and pressurization system for an enclosed cab of a surface drill, it was determined that the drill operator's respirable-dust exposure was significantly increased during time periods when the cab door was opened to manually guide another section of drill steel into place to achieve additional cutting depth. Although no dust cloud was visible when the door was opened to perform this task, the drill operator's exposure was documented (over a three-day test period) to be nine times higher than when the cab door was closed. Even at this higher respirable-dust concentration, the drill operator's exposure remained well below the permissible exposure limit governed by the federal dust standard; however, an alternative method is being investigated to guide the drill steel in place in order to eliminate this increased exposure. .

Jan 1, 2008

Introduction The Coal Mine Roof Rating (CMRR) is a roof classification system. It was first introduced to the mining community in 1994.The CMRR filled a longstanding need to quantify geologic description of coal measure rocks into an engineering value that could be used for mine design. It has now been written to a user-friendly visual basic code that can be run on any PC with a Windows operating system. Background Rocks that form the roof of coal mines can vary widely and quickly in composition, extent, and defects. This results in an equally broad range of rock properties that can substantially affect the ability of the rock mass to form a stable mine roof. The CMRR was designed to evaluate the properties of the coal mine roof rock mass that contribute to its weakness and convert them into a relative strength rating from 0 to 100. These properties include the cohesion and frequency of discontinuities like bedding, slips, shears, and joints; uniaxial compressive strength (UCS); and moisture sensitivity. With simple lab and field tests and observation, the CMRR can be calculated by technical and operating personnel with a minimum of training. The CMRR has been widely accepted in both U.S. and international coalfields. As a result, a number of roof control applications have been found for the CMRR. It is currently used as an input component in the Analysis of Longwall Pillar Stability(ALPS) program, which is used to design longwall chain pillars. Incan be used as a criterion for determining the appropriate width of mine entries. It has also been used to indicate the appropriate length of cut in weak ground. The CMRR can be used as a strength parameter to characterize inter burden between mined seams in the numerical modeling of subsidence effects. In any area where an estimation of coal measure rock mass strength is required, the CMRR can be adapted to fill this need. How It Works Originally designed to be used with underground exposures, the CMRR can also be calculated from core. The chisel test for bedding cohesion and the ballpeen hammer test for UCS are inappropriate for core. These tests have been replaced by point load testing both axially and diametrally. Two other measures that are common to standard core logging—Rock Quality Designation (RQD) and fracture spacing—are also used to estimate rock weakness. With these easily obtained parameters, the CMRR can be calculated from core and used in the mine planning and exploration phase. The input screens allow calculation of the CMRR for both underground exposure and core. The CMRR is reported both as a “dry" value and as a groundwater-adjusted value for moisture-sensitive rocks. There is a graphical output report featuring a lithologic column with annotated unit ratings and a roof bolt symbol representing the height of the bolted horizon. Another important feature is an AutoCAD interface. This feature allows the export of located CMRR data directly to an AutoCAD layer in XYZ form. In this way, drill hole data can be inserted directly to a base map.

Apr 1, 2003

To develop a cost-effective tool for improving the performance of rock drilling systems used in detecting and delineating underground mine voids and for coal exploration. Approach To investigate admixtures of polyethylene oxide (PEO) at zero surface charge concentrations as drilling fluid additives to enhance penetration rates and extend bit life in rock drilling systems. Background Bureau researchers have investigated the use of chemical additives to enhance drilling performance and found that the most efficient drilling occurred when the drilling fluid was able to maintain a zero surface charge (ZSC) on the surface of the rock being drilled. Laboratory drilling studies have been performed on rock types such as quart¬zite, granite, taconite, and marble. The lab tests were conducted using 5/8-inch diameter diamond-impregnated coring bits with cationic compounds as the surface charge neutralizing additives. These studies demonstrated enhanced drilling performance, however, only at the singular additive concentration that produced the ZSC condition.

Jan 1, 1991

1. In 2003, 14,391 mining operations reported employment statistics to the Mine Safety and Health Administration (MSHA). Almost half (49%) were sand and gravel mines, followed by stone mines (30%), coal mines (14%), nonmetal mines (5%), and metal mines (2%).

Feb 1, 2005

By R. L. Grayson, S. S. Peng

"Research has been conducted during the past year on a study to correlate respirable coal mine dust characteristics with worker positions and coal seams. The first characteristic of respirable coal mine dust which has been addressed in the correlation study is respirable dust mass concentration. In fulfillment of this objective, two mines operating in different coal seams have been selected for respirable dust mass sampling on both longwall panels and continuous mining sections. At present, sampling has been completed on the longwall panel operating in the first mine, and one half of the planned sampling has been accomplished on the continuous mining section.The first mine sampled is operating in the Pittsburgh coal seam. The average mining height is approximately 78"" with an average of 8"" of bottom shale being mined. The mine is primarily a longwall mine, and continuous mining machines are used to support the longwall.Figure 1 shows the layout of the longwall panel which was sampled. Intake air is coursed via the track heading up to the headgate area. The air splits at the headgate. Approximately 20,000-30,000 cubic feet of air per minute (CFM) is used to ventilate the longwall face and about 5,000-10,000 CFM is routed down the belt entry. Substantial leakage across the gob was noted during the sampling period. An average of 1800 CFM per 100 feet of face leaked through the shields into the gob from #1 shield to #112 shield. A substantial amount of leakage also occurred between the #1 shield and the solid rib of the headgate development panel. The path of the air used to ventilate the panel is shown with arrows in Figure 1. Direction of air flow was opposite to the coal moving direction on the armored face conveyor.A double-drum ranging shearer is used on the face to cut a 30-inch web of coal. Normal practice is to cut from the tailgate to headgate with the leading drum raised and the tail drum lowered for cutting bottom. After reaching the headgate, the shearer is reversed and both drums are lowered for a clean-up pass. The last 40 feet of face on the tailgate is cut on the clean-up pass.The shearer is equipped with 2 banks of 4 water sprays each and 2 large sprays on the headgate end and 1 bank of 4 sprays on the tailgate end. Additionally, sprays are located above bits on the cutting drums. Actual cutting speed was approximately 14-18 feet per minute, depending on conditions.The cross sectional area for air flow on the face was approximately 60 square feet before a pass was mined and 80 square feet after a pass was mined but before the shields were advanced. The cross sectional area at the shearer was about 35 square feet.The condition of both the tailgate and headgate of the panel was good with no signs of significant roof problems. The roof conditions along the face during the sampling period were variable. At times, as much as 3 feet of drawslate fell from the roof for a span of as much as 40 shields. Generally, however, relatively local areas of falling roof were encoun-tered, usually limited to a 10-20 shield span when appearing.Ten days were spent gathering respirable dust samples on the longwall panel. Mine Safety Appliance (MSA) sampling units equipped with 10-mm nylon cyclones, pre-weighed MSA PVC filters, and constant-flow DuPont pumps were used to obtain thesamples. The pumps were calibrated at a 2 liters-per-minute flow rate. The 10-mm cyclone was selected for classifying total dust into the desired respirable fraction in order to obtain ""legally defined"" respirable dust samples for detailed physical characterization."

Jan 1, 1988

Control surface stream loss by identifying and selectively sealing water loss zones in stream channels overlying underground mines. Approach Electromagnetic terrain conductivity surveys, coupled with stream gaging, are performed within a stream channel to identify saturated fracture zones associated with loss of stream water. This information is used to target locations for the injection of expandable polyurethane grout. The grout is injected two to three feet beneath the surface of the strcambed, across each loss zone, to seal the fractured strcambed and restore stream flow across the damaged area. How It Works Multiple zones of infiltration (natural and induced) normally exist in stream channels overlying mined areas, causing water handling and/or acid drainage problems in the mines as well as loss of stream flow. It is typically difficult to accurately locate these loss points. Therefore, Conventional methods of stream repair, such as using plastic membranes or clay and rock rip-rapping, are applied to long lengths of a stream channel. The two step approach developed by the Bureau of Mines First quickly and accurately locates loss zones using electromagnetic ground conductivity survey and gaging instruments. Conductivity is measured at fixed spacings (typically 25-50 ft depending on the instrument and desired observation depth), Ground conductivity increases when saturated conditions exist at depth. These apparent flow loss zones are confirmed by gaping, to eliminate possible effects due to unobservable metal debris adjacent to or buried in the stream sediment.

Jan 1, 1991

By T. E. Marshall, D. R. Dolinar, C. S. Cornpton, L. J. Prosser, A. T. Iannacchione, D. C. Oyler

The U.S., Australian, and United Kingdom coal and the Canadian hard rock mining industries have long recognized the significance of high horizontal stresses as a factor affecting the stability of roof and rib conditions in underground mines. Recently, a growing segment of the U.S. underground stone mining industry has also begun to recognize that horizontal stresses occur in some of its more than 90 mines. Considering the typically high strength and massive nature of limestone, this fact is a revelation in itself. High horizontal stresses produce extensive and sudden rock failures and, in some cases, resulted in injuries to mine workers. Through the years diverse control strategies have been proposed and experimented with. Reorientation of mine entries to reduce stress concentrations have proven successful and are widely accepted in practice. Other solutions, like rock reinforcement, are poorly understood and less accepted in practice. It is the purpose of this National Institute for Occupational Safety and Health (NIOSH) study to develop a better fundamental understanding of these ground control strategies under high horizontal stress conditions through a series of field and laboratory studies. To this end a design technique is presented which provides stone miners with a method for making stability assessments. The consequences of widening rooms, changing geology and horizontal stresses, and different rock bolts on roof beam failures are discussed.