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By R. R. Sayers

"Health hazards in the mining industry may be attributed to (1) abnormal conditions of the air, (2) improper sewage disposal, (3) bad drinking water, (4) bad illumination, and (5) local mechanical irritation.Abnormal conditions of the air may be due either to physical or chemical changes. The physical changes are (1) abnormal temperature, (2) abnormal humidity, (3) air movement, and (4) presence of dusts. Dusts may be either poisonous, as salts of lead, arsenic, zinc, or mercury; or nonpoisonous, as dust from coal, silica or quartz, limestone, gypsum, or silicates. Chemical changes may be due to changes in the normal constituents, as lowered oxygen or increased carbon dioxide; or to the addition of abnormal constituents, as carbon monoxide (white damp), hydrogen sulphide (stink damp), sulphur dioxide, methane (marsh gas, fire damp), hydrogen, and nitrogen.Effects of High Temperatures and Humidities The effects of various temperatures and relative humidities have been studied in mines in many countries. Harrington and myself studied them in the metal mines of this country and, in a report written recently, they have been summarized as follows:A. Remaining at rest in saturated air at 91 1/2° F, for one hour, With no air movement caused -1. An increase in body temperature;2. A moderate increase in pulse rate;3. Profuse sweating;4. After effects of dizziness and weakness with air movement caused ¬1. Slight or no increase in body temperature"

Dec 1, 1924

By Noel N. Moebs

Studies by the Bureau of Mines have identified geologic structures in mine roof rock that contribute to many roof falls in Appalachian coal mines. These structures, including paleochannels, scours, pinchouts, slickensides, clay veins, crevasse splays, and joints, can often be identified during, and sometimes before, mine development. Mine projections can be revised to reduce the adverse effects of discontinuitites in roof structure; large roof areas of laminated sandstone or incompetent strata generally can be delineated or inferred from exploratory drill hole data, and the need for supplementary support can be anticipated. Accurate descriptions of roof geology also provide some indication of optimum length and type of roof bolts that should be installed.

Jan 1, 1981

By J. Owens

Advanced materials development ranks as one of the most important high-tech industries of the future in the United States. Recent breakthroughs can be attributed to advanced computer technology, powerful mathematical models, and more precise analytical tools that enable scientists to examine and control properties of materials as never before. Discoveries now being made are providing many industries with opportunities to improve product lines, fabrication techniques, product reliability, and so forth. More¬over, industries, such as space, medicine, and defense, which require stringent: design and perfomance specifications in highly competitive world markets, increasingly demand these new materials. The definition of advanced materials used here is one that has been adopted by the U. S. Bureau of Mines: Those materials which have been developed over the past 30 years or so, and which are being developed at present, that exhibit greater strength, higher strength-density ratios, greater hardness, and/or one or more superior thermal, electrical, optical, or chemical properties, when compared with traditional materials.

Jan 1, 1991

By A. N. Baldwin

This report documents work performed under Bureau of Mines Contract J0265029 to study and develop two innovative mining systems: ? An underground auger capable of augering into the right and left ribs without repositioning the machine ? A conventional mining system employing recently developed innovative machinery. The report is separated into two volumes to document the two studies separately. Volume I describes work performed and the recommended concept for a bidirectional auger. Volume II describes the studies of mining equipment performance and mining plane developed to determine a conventional mining plan offering improved productivity.

Jan 1, 1977

By J. P. Coughlin

Gypsum plaster is calcium sulfate hemihydrate (CaS04-1/2H2O). There are two varieties, commonly designated as a and ß. The hydration setting) of this plaster involves the chemical reaction: CaS04?1/2H20(c) + 3/2H20(l) = CaSO4?2H20(c); that is, the hemihydrate combines with water to form the dihydrate. Many substances, when present as impurities, either in the hemihydrate or the water have influenced the rate of the hydration reaction. The objective of the Bureau of Mines work described in this report was to investigate the accelerating or retarding effects of small amounts of dissolved substances and to attempt to classify these effects upon a chemical basis. To eliminate competing effects, the work was conducted separately on the two varieties of hemihydrate; both were in highly pure form. (Commercial plasters usually are a mixture of the hemihydrates, with other substances present as impurities.) As the hydration reaction of each variety of hemihydrate evolves heat in amounts known from previous work, 5,6/ the authors decided to use calorimetric methods to follow the extent of the hydration reaction as a function of time. Two calorimetric methods were employed. One was designed to study the hydration reaction with a large water to plaster ratio and the other with a small water to plaster ratio (to simulate commercial practice in utilizing plaster).

Jan 1, 1959

By Louis A. Panek

This report deals with the combined friction and suspension effects in the reinforcement of horizontally bedded mine roof by bolting. Other reports have treated these two effects separately. Friction effect refers to the reduction of bending in a laminated roof due to the clamping action of tensioned bolts. If the beds tend to have unequal deflections, the bolts oppose this tendency, thus creating a suspension effect, which consists of a transfer of part of the weight of weaker or thinner beds to the flexurally more rigid beds within the bolted unit. The combined effects of friction and suspension on the bending of the beds, whether an increase or a decrease, are difficult to generalize because they depend on the bedding sequence and the bolt pre-tension. Some analysis of the bedding sequence usually is required to determine the critical bed within a set of bolted beds. However, if the suspension effect is substantial and if the bolts are pre-tensioned, then the greatest bending stress is likely to occur in the thickest bed. Findings are based partly on theory and partly on tests of mine-roof models in a centrifuge, which were found to verify the theory. Mathematical formulas are obtained for the change in maximum roof bending stress and for the change of roof deflection due to the combined friction and suspension effects. The maximum bending stress is needed for designing a roof-bolting system and the deflection for evaluating its effectiveness.

Jan 1, 1962

By W. G. Hopkins

The development of systems for location of miners who have become entrapped following a mine disaster has been one of the major research goals in the Bureau of Mines. This study details the preliminary development of such a system. Current technologies for locating trapped miners from the surface are either simple direction finders or time difference pulse systems that have accuracy limitations. Developing technologies using full vector field measurements at several receiving points are currently being studied. The necessity of measuring field strength with great accuracy can be a drawback in these systems. A system that operates with continuous wave radio signals, whose phase differences can be measured accurately even in weak signal conditions, greatly improves the location accuracy. A microcomputer would be used in conjunction with the system, to gather and manipulate the data to automatically pinpoint the location of the trapped miner. Comparison of this system with existing technology indicates a favorable accuracy/complexity ratio for the phase difference of arrival technique.

Jan 1, 2011

By William H. Lyon

In 1950 the Program Staff of the Department of the Interior undertook an exploratory study in the projection of energy requirements of the nation. This work was reported in Bureau of Mines Information Circular 7582 by H. J. Barnett. In that preliminary study Mr. Barnett, after exploring the nature of the energy economy in some detail, evolved a method for estimating how much energy will be required in the future, based on estimates of trends in efficiency of energy utilization in specific applications, the physical output of specific energy-consuming industries, size of the population, productivity advances in the economy at large, consumer preferences, and other factors. Considerable new information was developed regarding the nature of energy demands and the possible levels of requirements for each fuel under various assumed business conditions. The study analyzed the interrelationships, including substitutions, among the fuels and emphasized the need for viewing the energy economy as an integrated albeit complex whole. This exploratory study showed a need for a single comprehensive statistical re-port that would assemble and show in a uniform manner the diverse published statistical data on energy commodities now scattered through many publications. A particularly important need was for a set of historical statistics showing the production and consumption of all energy on a B.t.u. basis. As the prospective size and nature of the future energy requirements of the nation are matters of continuing importance, this report was prepared to assist further investigations of the subject. In this report the authors undertake to assemble and present in tabular form, on a uniform basis, the production and use of each of the fuels and electric energy in the United states for three census years -1929, 1939, and 1947. The year 1947, rather than a later year, was selected because it is the most recent year for which census data are available showing the consumption of fuel by each of the manufacturing industries. It is hoped that making data for these 3 years available in one re-port will provide the needed statistical background for further studies of fuel requirements and supplies.

Jan 1, 1951

By F. W. Wood

Ingots of zirconium and other highly reactive metals such as titanium and hafnium produced by the consumable-electrode arc-melting process require conditioning before forging or rolling. A nondestructive, arc-conditioning technique has been developed as a substitute for lathe conditioning. The technique employs en electric arc under an inert atmosphere to fuse surface metal on the sidewalls of ingots without seriously affecting the general quality of the ingots. Advantages of the practice are Increased yields, lower accumulation of inferior scrap, and actual cost savings. The work cited in this report was done on zirconium. INTRODUCTION The consumable-electrode arc-melting process as practiced at the Bureau of Mines3 4/ has proved to be a technique for producing sound, homogeneous, commercial-size ingots of zirconium and its alloys. Ingots produced by this process, however, have as a characteristic a layer of partly fused metal on the sidewall to a depth of 3/16 to 3/8 inch. To prevent extension of surface imperfections during forging, the ingots are ordinarily conditioned by removing defective material in a lathe. If the metal were less reactive or the requirements less severe, the machine chips could be recycled and remelted. However, zirconium, being so oxygen sensitive, is contaminated by merely being machined despite extensive cooling of the tool bit. Further, being contaminated with oxygen, the chip metal upon remelting is 10 to 25 Brinell-hardnese numbers harder than the ingot from which it was machined. For this reason, the ingot specifications for naval reactor use have prohibited remelting machine chips, except as required for starting pads. Again, were zirconium less costly or less in demand this ever-increasing pile could be burned to oxide and recycled through the Kroll sponge process. Economics do not favor this, as melting feed stock has an estimated increase In value over oxide of about $8.80 per pound of contained zirconium. The efforts of the Bureau to solve the problem have been directed along two lines: To reduce the contamination of the machine chips produced and to reduce the quantity of the chips produced. This paper presents the technique developed to reduce the quantity of chips produced by arc-conditioning the remelted ingot.

Jan 1, 1955

By H. E. Powell

A series of alkyl-dithiocarbamic acid amine salts was prepared and tested as collector for slimed lead minerals contained in the waste material from a commercial lead ore concentrator. The reagents, members of a homologous series differing only in the number of alkyl radicals in their structure, were prepared by reacting stoichiometric amounts of primary amines and carbon disulfide in a cold alcohol solution. Subsequent purification was by recrystallization from absolute ethyl alcohol solution. Evaluation was through froth flotation of a mill tailing containing 0.2 percent lead. Results show that maximum recovery (38 percent) was obtained with the reagent containing 8 alkyl radicals, but that maximum rougher concentrate grade (4.8 percent) was obtained with the reagents of intermediate number of radicals.

Jan 1, 1962

By C. M. K. Boldt

This report summarizes five separate Bureau of Mines contract studies on the use of aerial photogrammetry, satellite transmission of in situ instrumentation information, and satellite imagery to monitor and update mine waste embankment data. The equipment used, methods applied, results, recommendations, and cost analyses are presented along with a bibliography of related investigations.

Jan 1, 1987

By Thomas M. Barczak

The safety of mine workers depends on the proper installation of roof supports to prevent the ground from collapsing into the working areas of an underground mine. As new support systems are developed, they need to be properly evaluated to make sure that they are capable of providing adequate roof support before they are first used in a mine. In addition to making certain that the supports meet basic safety criteria, the limitations of the support need to be fully defined in order to avoid improper application of a particular support design. The National Institute for Occupational Safety and Health (NIOSH) operates a world-class facility called the Safety Structures Testing Laboratory. This laboratory contains a unique load frame, the Mine Roof Simulator, which is capable of simulating the ground behavior in underground mines for conducting full-scale evaluations of roof support systems. Safety performance testing protocols using the unique Mine Roof Simulator have been developed for both standing roof support systems and longwall shield supports. The purpose of this paper is to describe these test procedures. The protocol for standing roof supports incorporates seven test series:( 1) uniform loading baseline tests, (2) height evaluations, (3) asymmetric loading, (4) biaxial loading, (5) load rate studies, (6) active loading determination, and (7) static loading evaluations. For longwall shields, a four-series test program that accurately simulates in-service conditions on a longwall face is proposed. This test program consists of (1) transfer of horizontal load to the caving shield-lemniscate assembly (zero-friction test),(2) point loading of shield joints due to lateral movement or rotation of the canopy, (3) evaluation of leg socketand leg cylinder integrity, and (4) face-to-waste racking of the shield. In addition, an evaluation of the shield’s hydraulic components will be conducted prior to the performance testing. These protocols will provide state-of-the-art safety performance evaluations of emerging support technologies, as well as a means to assess the safety of both new and aging longwall shields. Hence, this effort will enhance the safety of mine workers by ensuring that critical support elements are properly designed and that aging supports are retired before their support capability is jeopardized.

Jan 10, 2000

By Horace C. Porter, F. K. OVITZ

Much has been written of the changes undergone by coal in storage and the deterioration of coal through exposure to the weather. In order to obtain definite information for the benefit of the Government departments and of all who store coal in large quantitieS', a series . of tests was begun in the fall of 1909 under the supervision of tT. A. Holmes, then chief technologist of the United States Geological Survey, and was continued by the Bureau of Mines after its establishment in 1910. The tests were confined to determinations of the loss in heating value of the coals and did not include a study of other deterioration; for exaIp.ple, in coking quality or the yield of by-products in coking. The Bureau of Yards and Docks of the Navy Department cooperated in tests of New R~ver (W. Va.) coal, a variety largely used by the Navy. A preliminary report presenting a brief account of the early results of these tests has been published by the Bureau of Mines as Technical Paper 16.a The detailed report is presented in this bulletin, which gives a fu11 account of the tests and the analytical data covering a period of five years' storage. Data of somewhat similar experiments for shorter periods with gas coal from the Pittsburgh bed, with Pocahontas coal on the Isthmus of Panama, and with Sheridan, Wyo., subbituminous coal, which is used for railroad and other purposes in the West, are included. The tests of New River coal, in cooperation with the Navy Department, were undertaken to determine the advantage to be gained by storing coal under water, and particularly under salt water. Small lots were used in order to make the tests of maximum severity, and parallel experiments were made with run-of-mine and crushed coal under one-fourth inch size. All of the small lots tested under the different conditions (except those tested near Key West, Fla.) were taken as representative portions from one large original lot. The tests of Pocahontas coal, which, like the New River, is semibituminous, were undertaken chiefly to determine th.e effect of the tropical conditions in Panama. They were made on an outdoor pile of 100 tons of run-of-mine coal. Pittsburgh gas coal, a high-volatile, bituminous type used at gas and by-product coke works, was exposed for test at Ann Arbor, Mich., in cooperation with the University of Michigan. The university agreed to make tests at successive intervals of storage to determine, in its illuminating-gas experiment station, the yields of gas and byproducts from the coal. The coal, screened lump, was stored in about 4-ton lots out of doors in open bins. Subbituminous coal, which is mined in Colorado, Wyoming, and other States, and is known also as "black lignite," is commonly supposed to deteriorate rapidly in storage, especially by "slacking" or crumbling of the lumps. The tests herein described were undertaken at Sheridan, Wyo., in cooperation with the Chicago, Burlington & Quincy Railroad Co., in order to determine the extent of this slacking and the accompanying loss of heat value. The tests were in open bins holding 4 to 12 tons.

Jan 1, 1917

By Seth C. Schaefer

The Bureau of Mines investigated the standard Gibbs energies of forma-tion AGfo, for NiCr204 (nickel chromite) and CoCr204 (cobalt chromite). High temperature galvanic cells employing stabilized ZrOz (zirconia) as the solid electrolyte were used to measure the open-circuit potentials for the cell reactions ?

Jan 1, 1986

Metals From Oil Shale. -A Geological Survey News Release in mid-January indicated that a surface sample analysis of oil shale in central Montana found a ton of shale to contain up to 13 pounds of zinc, 2 pounds of nickel, 1.8 pounds of molybdenum, 16 pounds of vanadium oxide, and nearly a quarter pound of selenium. It might be possible to recover some of these metals economically on a byproduct basis. The shale in central Montana was also estimated to contain 180 billion barrels of synthetic crude oil, which compares to estimated oil reserves in the Middle East of 360 billion barrels. Merchant Fleet Dwindles. -The National Maritime Council reports that although the U.S. is the world's largest trading power and that well over 90% of its foreign trade is conducted by shipping, the U.S. fleet is tenth in absolute numbers and less than 5% of its foreign trade is carried on U.S. ships. In 30 years, the U.S. fleet has dwindled from over 4,000 oceangoing vessels to about 600. U.S. ships carry less than 2% of imported iron ore, bauxite, and tungsten, and only 3% of oil imports.

Jan 1, 1981

By Thomas H. Dubaniewicz

Fiber optic systems are being deployed in locations where explosive gas atmospheres are normally present or are present under fault conditions. The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory (NIOSH, PRL) conducted a study of laser safety in potentially flammable environments. Researchers conducted experiments to estimate the mean and standard deviation of laser powers needed to ignite 6% methane-air atmospheres using single mode optical fiber tips covered by two types of iron oxide (Fe304 and (FeMn)203) mixed with a ceramic adhesive. The iron oxides, heated by a 1064 nm continuous wave laser, ignited the methane-air mixtures ,at similar powers. The minimum igniting power and maximum non-igniting power (10 tests) were 407 and 350 mW, respectively, using a 62.5 pm fiber. Laser beams guided by 125 and 80 pm diameter cladding single mode fibers produced similar methane-air igniting powers. Ignition was not observed using coal particles at powers that produced ignition with the iron oxides. Threshold ignition delays using the single mode fiber were approxinlately proportional to the inverse square of the igniting power. Ignition delays were significantly longer than the reported activation time for a comnlercial fiber optic power limiter. Comparisons are made with the results of other researchers. Published by Elsevier Ltd.

By James W. Martin

This user?s manual analyzes the application, selection and performance of hopper/crusher/conveyor systems used with front-end loaders in surface mining operations. It is designed to be used in conjunction with its companion manual: "Guideline Manual for Front-End Loader Load-and-Carry Applications" Aspects of the application are covered as well as design considerations of the hopper/crusher/conveyor units. Lists of equipment manufacturers, crusher specifications, together with a series of checklists, are included for preliminary analysis.

Jan 1, 1982

By I. S. Solet

This study, of the liquidus temperatures and densities of molten alloys of zinc and aluminum was made as part of a broader investigation on refining of scrap aluminum. One of the methods of refining involves the separation of liquid and solid phases by gravity segregation and by filtration. More accurate data were required on the liquidus temperatures and the densities of molten' mixtures of the metals than were available in the technical literature. New data on the liquidus curve were obtained by thermal analysis. The new temperatures are, for the most part) somewhat higher than those reported previously by other investigators. The density of molten mixtures of zinc and aluminum were found to be less than would be calculated by assuming that the two metals occupy the same respective molal volumes in solution as they do as pure metals.

Jan 1, 1949

By J. H. Schuenemeyer

Consider a set of points, some of which are anomalous (larger than a specified cutoff value), located on a plane. Whether some or all of these points are clustered to form one anomaly or more or, alternatively whether these points are scattered at random, may be investigated by measuring perimeters of convex hulls. A convex hull is the smallest convex polygon that will encompass a group of points. (Examples of convex polygons are triangles, rectangles, and all other regular polygons.) A set of anomalous points is selected and the perimeters of the convex hulls of this set and all its subsets are measured and compared with tabulated values of perimeters for each subset size. For a given subset size consider those perimeters which are less than the tabulated perimeter. If the number of convex hulls is greater than the maximum number expected by chance, then the chance that any one of the observed-hulls-is a nonrandom cluster is the ratio of the observed number to the sum of the observed and the maximum number expected by chance. Otherwise, the points are evidently not clustered. If many sample points are anomalous, an alternate model defines various configurations of contiguous points and compares the observed number of configurations per unit area with the expected number. Applications are discussed in several fields of geology and geochemistry-including geochemical exploration surveys and heavy mineral spatial distributions--as well as in mining (dust control) and medical geography.

Jan 1, 1972

By R. T. C. Rasmussen

"INTRODUCTION The primary purpose of the Bureau of Mines electrolytic manganese pilot plant at Boulder City, Nev., is to improve the Bureau-invented electrowinning process and to determine the applicability of the process to the extensive domestic low-grade manganese ores with a view to making the United States dependent upon foreign sources of manganese. 3/4/ Incidental to accomplishing this purpose, the pilot plant has produced a substantive quantity of electrorytic manganese since the start of operations late in 1941; present cabacity about 1 ton a day of manganese metal. A second important purpose of the pilot plant is the supplying of electrolytic manganese for full-scale tests in cooperation with industrial users of manganese.The Rustless Iron& Steel Corp., Baltimore, Md., was the first steel company to cooperate with the Bureau of Mines in large-scale testing of electrolytic manganese. Arrangements were made with C. E. Tuttle, then president of the corporation, whereby the Bureau would supply electrolytic manganese to make a sufficient number of full-scale stainless-steel heats to demonstrate thoroughly its merits as a replacement for low-carbon ferro-manganese in the corporation's stainless-steel practice. The corporation's purpose in the investigation was to determine the possible advantages of electrolytic manganese resulting from its almost complete lack of phosphorus and caroon that might offset its then considerably higher cost per unit of manganese than low-carbon ferromanganese. The data presented herein are based upon reports of A. L. Field, technical director, and L. Weitzenkern, research engineer of Rustless Iron & Steel Corp.; they are supplemented by observation of the author who visited the plant during the tests."

Oct 1, 1945