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By M. A. Mahtab

This report presents a new procedure for analyzing the orientations of rock fractures in an engineering site. This procedure, coded in a computer program, identifies clusters or groupings among the fracture orientations and calculates (1) the mean orientation of the fractures within each cluster and (2) the dispersion or scatter among these fracture orientations. Data points are represented by intersections of joint normals with the upper hemisphere, which is divided into 100 equal-area quadrilateral patches. The points in adjacent patches where the Poisson distribution test shows significant concentrations are assigned to a single cluster. For a cluster whose fracture orientations follow Arnold's hemispherical normal distribution, a confidence interval for the fracture orientation mean is calculated by applying Fisher's estimates. The technique is applied to the treatment of three examples.

Jan 1, 1972

By Roger E. Burleigh

In June, 1989, the U.S. Bureau of Mines, undertook a 9-day evaluation of the tin resource potential of the Sleitat Mountain tin deposit. Significant tin-tungsten mineralization is associated with quartz-topaz-white mica-tourmaline greisen alteration of a multi-unit, 57 Ma, peraluminous, granite stock which intrudes Cretaceous Kuskokwim Group flysch deposits. The granite comprises marginal biotite-, intermediate biotite-muscovite-, and central zinnwaldite-granite units, interpreted as a zoned alteration system. Major vein mineralization is confined to two east-west-trending zones of steeply oriented tabular lenses of greisen interleaved with mildly altered granite. Cassiterite is the dominant ore mineral while arsenopyrite, loellingite, wolframite, pyrite, sphalerite, chalcopyrite, and bismuth-oxides are present in minor to trace amounts. The north and south greisen zones are estimated to contain an inferred resource of 128 to 212 million lbs Sn in 28.6 million st of mineralized rock. An 1,800-lb representative bulk sample contained 0.37% Sn, 0.04% W and 17 ppm Ag and is considered an average grade estimate for the deposit. Drill testing by Cominco Alaska Exploration indicates that substantial widths of high-grade tin mineralization are included within the lower grade disseminated mineralization. Depth of deposit erosion is substantial and there exists a high probability for placer tin deposits.

Jan 1, 1991

By Marie Farnsworth

"The Anhydrite ProblemThe Nonmetallic Minerals Experiment station of the Bureau of Mines at Rutgers University, New Brunswick, N. J. has recently undertaken a study of the chemical and physical properties of anhydrite having in view its wider utilization anhydrite (CaSO4) in contact with water at ordinary temperature and pressure rehydrates, slowly forming gypsum (CaSO4.2H42O). In nature this is an extremely slow process, and laboratory experiments are being conducted to determine methods of accelerating the rehydration. The tests recorded herein cover one this study, and while they are negative in character in so far as the major problem is concerned, certain facts established by the tests, bearing on the stability relations of gypsum and anhydrite seem sufficiently important to be placed on record.Early Researches on Gypsum and Anhydrite.It is to Lavoisiar that we are the first scientific study of the calculation and hardening of plaster of Paris. He sums up his experiments in the following passage: ""If gypsum, which has been deprived of its water of by means of heat, is again treated with water (to make what is commonly called mortar) it takes it up with avidity, rapid and irregular crystallization occurs, and the small crystals which are formed are so entangled in each other that a very hard mass results."" Later, he observed that the dehydration of gypsum occurs in two stages: three-fourths of the combined water is much more easily driven out than the last fourth. LeChatalier first determined the temperature decomposition accurately, his method was as follows: Pulverized gypsum was placed in a glass tube in the middle of a paraffin bath, the temperature of which was raised in a progressive and regular manner. A thermometer gave at each instant the temperature the salt, and the passage of the mercury column past each division of —co. was cared by a registering chronograph. The rise in temperature was except at 128°C. and 168°C. where breaks occurred."

Nov 1, 1924

By Robert H. Peters, George R. Bockosh, Barbara Fotta

This paper was commissioned by the Japan Technical Cooperation Center for Coal Resources Development. It is to be published in a proceedings following a series of presentations to Japanese coal officials in February 1997. The paper focuses primarily on summarizing the past 20 years of U.S. research on promising techniques for ensuring that underground coal miners work safely. These techniques can be grouped into three major categories: management, workplace design, and training. Each technique is described, and the results of efforts to apply the technique at underground coal mines are summarized. Recent statistics on accidents and productivity in U.S. underground coal mining operations are presented before the overview of research findings is given. Because Japanese coal mines are using the longwall method of coal extraction, separate statistics are given for U.S. longwall versus room-and-pillar coal mining operations.

By Robert P. Vinson, Fred N. Kissell, Edward D. Thimons

Because of the high number of accidental methane gas ignitions in metal and nonmetal mines, the Bureau of Mines searched for a simple guideline that would allow mine personnel to evaluate the methane hazard in a given mine. Air samples were collected by the Bureau in 53 metal and nonmetal mines and analyzed for trace evidence of methane gas. Samples were collected in the returns and at the working faces. Those mines classified as gassy by the Mine Safety and Health Administration had a significantly higher average methane concentration than those classified as nongassy. Of the 9 gassy mines sampled, 7 had methane concentrations above 100 ppm, whereas only 1 of the 44 nongassy mines had a concentration above 100 ppm. The 100-ppm concentration may be used as a simple and convenient guideline for forecasting the methane hazard in a mine, whether or not the mine is classified as gassy. There was no consistent correlation between commodity mined and methane concentration, nor was there a correlation between mine depth and methane concentration. Neither of these factors can be considered a guideline for predicting methane hazards.

Jan 1, 1979

By Sam S. Taylor

Subsurface disposal of oil-field brines was practiced in Oklahoma on a limited scale as early as 1925. The technique of subsurface injection has been improved immensely and has been applied with varying success in many oil-producing areas in Oklahoma, and elsewhere. This method of disposal, however, is only one of several methods available to operators of oil-producing properties, but, in contrast with usual methods of handling brines on the surface it eliminates the damaging effect of mineralized water on fresh-water supplies, vegetation, and aquatic and other animal life. Other methods of brine disposal approved by regulatory agencies in some States include (1) impounding in impervious ponds and solar evaporation, (2) controlled diversion into surface waters, and (3) recovery of the mineral salts of the brine. In most States where oil is produced regulatory bodies authorize the use of one or more of these methods of brine disposal. In Oklahoma, for example, the .Oklahoma Planning and Resources Board of the Conservation Commission has been authorized4/ to adopt whatever methods or means may be necessary to prevent contamination by mineralization of all potable waters within the State.

Jan 1, 1942

Now you know why there is concern about mine illumination. You have some idea about how the human eye works and about the problems of glare, peripheral vision, and accommodation. And you know that lighting in a mine presents special problems because of the dark surroundings and low reflectance. This chapter describes what can be done to improve conditions. This chapter begins with a short discussion about Federal Standards on mine lighting -- what they are and what is being done to carry them out. The chapter then describes different types of lamps that can be used for mine lighting, and discusses their advantages and disadvantages. Finally, the chapter lists some things that you can do personally to improve lighting, or can point out to others so that improvements can be made. The Federal Government is doing its part to improve mine lighting by establishing regulations. Lamp manufacturers are constantly studying new lamps to provide better equipment. And your company will do its part to comply with regulations. Better lights may not be here yet, but they will be soon. But in the end, you are the one who will be using the lights, and you are in the best position to see the improvements. You are also in the best position to see and tell others where further improve¬ments can be made.

Jan 1, 1976

By C. W. Vierrether

Tailings from the Pea Ridge iron mine contain significant amounts of apatite, which has rare-earth element values associated with it. In association with the recovery of rare-earth minerals as a secondary resource, the U.S. Bureau of Mines conducted an investigation on the recover ability of the rare-earth minerals from these tailings. The mill tailings were subjected to a phosphate flotation to separate the apatite from other constituents. More than 70-pct recovery of the rare-earth values was achieved. Based on mineralogical characterization and prior analysis of rare-earth-bearing breccia pipe material at Pea Ridge, it is proposed that processing this phosphate concentrate on a vanner table would yield up to a 95-pct recovery of the rare earths in the concentrate, with the apatite reporting to the tailings. Intensive ore microscopy studies of the original tailings to the flotation products led to the identification of monazite, xenotime, and rare-earth-enriched apatite as the major rare-earth-bearing minerals in the tailings.

Jan 1, 2010

By Jon C. Volkwein

The industrial sand industry has been exploring new techniques to reduce dust. One company was experimenting with adding water during bagging operations to the surface of the hag, and into the product as it flowed into the bag. The Bureau of Mines, using instantaneous dust sampling instruments, measured the effectiveness of three methods of adding water. Results indicated that various types of water sprays applied in carefully controlled amounts could reduce dust up to 50% at worker locations at the bagging machine and inside a railroad boxcar. This report also discusses constraints such as product handling, customer acceptance, cold weather problems, dust collector performance, and other areas.

Jan 1, 1981

By W. P. Rumancik, C. P. Lazzara, A. C. Smith

The United States Bureau of Mines (USBM) developed SPONCOM to aid in the assessment of the spontaneous combustion risk of an underground mining operation. A prior knowledge of the spontaneous combustion risk of the coal and factors that increase that risk can be useful in the planning and development of proactive monitoring, ventilation, and prevention plans for the mining operation. Interactive data input screens prompt the user for information about the coal's chemical and physical properties, the geologic and mining conditions encountered in the mining of the coal, and the mining practices employed. During the input process, 'expand' screens provide the user with specific information on each input parameter. This information includes a description of the parameter and its effect on the overall spontaneous combustion risk. The program logic determines the coal's relative spontaneous combustion potential, based on the coal's proximate and ultimate analyses, and heating value. The program then evaluates the impact of the coal properties, geologic and mining conditions, and mining practices on the spontaneous combustion risk of the mining operation. The program output provides details on each factor that increases the risk of spontaneous combustion.

By Sam S. Taylor

Subsurface disposal of oil-field brines was practiced in Oklahoma on a limited scale as early as 1925. The technique of subsurface injection has been improved immensely and has been applied with varying success in many oil-producing areas in Oklahoma, and elsewhere. This method of disposal, however, is only one of several methods available to operators of oil-producing properties, but, in contrast with usual methods of handling brines on the surface it eliminates the damaging effect of mineralized water on fresh-water supplies, vegetation, and aquatic and other animal life. Other methods of brine disposal approved by regulatory agencies in some States include (1) impounding in impervious ponds and solar evaporation, (2) controlled diversion into surface waters, and (3) recovery of the mineral salts of the brine. In most, States where oil is produced regulatory bodies authorize the use of one or more of these methods of brine disposal. In Oklahoma, for example, the Oklahoma Planning and Resources Board of the Conservation Commission has been authorized to adopt whatever methods or means may be necessary to prevent contamination by mineralization of all potable waters within the State.

Jan 1, 1942

By W. H. Ode, W. A. Selvig

Investigations have shown interesting relationships between primary-tar and light-oil yields and chemical analyses of coals. These studies have been based largely upon results published by the Bureau of Mines in connection with its survey of the gas-, coke-, and byproduct-making properties of American coals. This paper gives the results of a similar correlation in which the range in rank and type has been extended to include nearly all classes of coal, the object being to determine relationships that are significant in predicting tar and light-oil yields from chemical analyses of coals. The yields of primary tar and light oil are important in two fields of coal utilization, namely, combustion and carbonization. It is generally recognized that the principal cause of smoke produced upon burning coal is incomplete combustion of tar and light-oil vapor released during burning. The greater the tar and light-oil yields of a coal, the greater is its potential smoke-producing property. During the present war, development of new sources of fuel oil has been emphasized, especially where the supply of petroleum products is limited. One possible source of a substitute fuel is the tar and light oil that can be obtained by low-temperature carbonization of coal. In both England and Germany large quantities of low-temperature tar and oil are being processed as a source of liquid fuels. It is obvious that primary-tar and light-oil yields are of paramount importance in the selection of coals for such use.

Mar 1, 1944

By John W. Cole

The Butte district has been the principal producer of metallurgical-grade manganese in the United States since World War I. Manganese dioxide nodules are produced from rhodochrosite ore by concentrating the rhodochrosite and roasting the concentrate in rotary "cement-type" kilns. The Anaconda Copper Mining Co. is the only producer at present. Under the stimulus of a purchasing program administered by Metals Reserve Company during World War II, however, several independently owned or operated mines (including the Norwich) produced manganese carbonate ore. These mines were examined in Juno 1949 by John W. Taber, mining engineer, Bureau of Mines. A core-drilling program to develop ore in the Norwich mine was recommended and approved. drilling was completed early in 1950. This report gives factual data obtained.

Jan 1, 1951

By B. V. Johnson

The Federal Bureau of Mines has conducted research in support of the National Aeronautical and Space Administration's (NASA) Apollo program to acquire fundamental scientific and engineering knowledge of lunar-mineral resources for NASA's Office of Advanced Research and Technology. Equipment and techniques were developed to conduct soil shear tests in a simulated lunar environment. Shear tests performed with this equipment in ultrahigh vacuum and controlled laboratory atmosphere showed that simulated lunar soil increased in strength in the simulated lunar environment.

Jan 1, 1973

By R. Barany

In this paper, closed expressions have been obtained for the frequency spectrum of a Born-Karman square lattice in terms of elliptic and hyperelliptic integrals. This work is part of continuing research by the Bureau of Mines with the thermodynamic properties of metals and minerals. Although other workers have obtained various types of approximations for the general case of the frequency spectrum of a square lattice, no one previously has obtained closed analytic expressions for this spectrum. To understand the optical and thermodynamic properties of crystals, several investigators have studied the distribution of frequencies of normal modes of vibration of the crystal lattice. Born and Karman3 laid the foundation for the theory of lattice dynamics and obtained detailed results for the case of a one-dimensional lattice. Blackman4 used numerical techniques to estimate the frequency distribution of a two-dimensional square lattice. Mbntroll5 analytically determined the frequency distribution of a square lattice for a particular value of the force constants. He also studied the more general problem and obtained some analytic approximations, using the method of moments. However, the calculations by this method were so difficult that it was not always practicable to carry them out. Van Hove6 and Montroll7 studied the nature of the singularities in the frequency spectrum of both a two and

Jan 1, 1962

By G. P. Houston

This is the final, report submitted for the Contract No. H0220002 with the U. S. Bureau of Mines for the design and development of a Permissible Automatic Data Acquisition System (PADAS) to measure and record roof stresses in underground mines Basically the PADAS is a portable, battery powered, 24-channel data acquisition system designed for safe unattended operation of up to 30 days duration in explosive environments. The unit will accommodate twenty-four pressure transducers or eight borehole deformation gages (or any combination) at distances up to 300 feet from the PADAS to measure pressures up to 10, 000 psig. All 24 channels as a selected group are scanned sequentially at one of several selectable rates.

Jan 1, 1973

By Steve C. Albrecht

The objective of this study is "to assess the impact of surface mining on soil compaction in the Midwest". The study revolves around a unique field sampling program targeted at four mine sites utilizing four distinct types of soil movement of midwestern prime land. Through the preparation of a final report for use as a guidebook, an assessment is made of the degree to which surface mining operations contribute to the soil compaction problem. The final report is formulated through the use of field study data as well as information gathered in an intense literature review. The final report centers on applying collected data to practical field applications. Soil sampling on the four mine sites centers on a comparison of natural and replaced soils for moist bulk density. This characterization evaluates changes in density and texture throughout the soil profile to a depth of 48 inches. Fertility of the topsoil is also assessed for natural and replaced soils. During field sampling and observations, a base of information has been gathered to compile a case study on each mine site. The report accesses the regulations in the prime farmland areas through the use of a matrix. The regulatory matrix allows easy access of mining personnel to State and Federal regulations.

Jan 1, 1982

Engineering controls for overburden drilling include dry dust collection systems, wet dust suppression systems, and enclosed cabs [Zimmer and Lueck 1986; Volkwein et al. 1979]. Proper maintenance of the dust suppression system is critically important for drills using dry dust suppression methods. Failure to rigorously maintain these systems will result in inadequate dust control. Acute silicosis has been reported in miners operating equipment that relies on dry dust suppression [NOSH 1992].

Jan 1, 1997

By Edward A. Barrett

The ability to recognize visual cues commonly associated with roof and rib hazards is fundamental to the prevention of groundfall accidents. The perceptual skills that miners possess to visually search and assess hazardous ground conditions differ considerably. This U.S. Bureau of Mines report summarizes recent investigations on the use of stereoscopic (3-D) slides as a training aid for improving the ability of miners to recognize the various geologic and mining-induced irregularities that cause ground-falls. The feasibility of using 3-D slides for training and their effectiveness for representing roof and rib hazard conditions are discussed. Information is presented on equipment and procedures for creating a 3-D slide program that can be updated by mine trainers. Recommendations are made on selection of 3-D equipment and on the use of 3-D slides for training miners to recognize roof and rib hazards.

Jan 1, 1988

By John L. Reuss

A laboratory study was conducted by the Bureau of Mines to investigate the technical feasibility of decomposing hydrous magnesium chlorides by using a steam pyrohydrolysis technique. This procedure consisted of injecting steam into the atmosphere of a decomposition furnace containing samples of hydrous magnesium chloride and determining the rate of hydrolysis by measuring the rate of chloride evolution. The variables investigated were temperature, amount of water vapor in the decomposition atmosphere, and hydration stage of magnesium chloride. The application of steam was shown to accelerate both the rate and completeness of magnesium chloride decomposition reactions. For example, when magnesium chloride hexahydrate is exposed to a furnace temperature of 600' C in an air atmosphere for 20 minutes, the decomposition is 37 percent. Under identical conditions in a steam atmosphere, the decomposition is in excess of 70 percent. The magnesium oxide produced by the steam pyrohydrolysis of magnesium chloride dihydrate at 800° C contained 98 percent magnesium oxide. Based on magnesium oxide composition, this is equivalent to that of burned magnesite produced at temperatures in excess of 1,300° C. To demonstrate the quality of the product on a practical basis, metal reduction tests have shown it to be equivalent to reagent-grade magnesium oxide as a carbothermic reduction feed material.

Jan 1, 1974