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Provide mine operators with a quick means of identifying the effect of cutting system changes on relative dustiness at the mine face, by developing an interactive computer program for drum-type coal mining machines. Approach A program which simultaneously evaluates machine parameters, coal seam parameters and mine operator-controlled parameters for their effects on relative dustiness has been developed for use on any minicomputer using BASIC computer language. How it works The interactive computer program allows mine operators to make one or more changes at a time to their cutting system to determine how these changes affect relative dustiness of the face. Using this program, mine operators can find the optimum cutting system configuration to minimize dust using their seam conditions and their equipment specifications. The mining machine variables include: number of vane bits, number of gage bits, number of starts, vane wrap, number of end ring lines, rpm, advance rate, ton/min, percentage of time spent cutting per shift, and airflow.

Jan 1, 1986

By B. W. Madsen

As part of a program to maintain an adequate supply of minerals and metals to meet national economic and strategic needs, the Bureau of Mines conducted research to determine the diffusion coefficients for ferric ions in synthetic copper leach solutions. Determination of ferric ion diffusion coefficients in typical dump leach solutions is necessary for predicting leaching rates of copper from large-scale leaching operations and for optimizing concentrations of ferric iron in solutions to maximize leaching efficiency. Derivative chronopotentiometry, an electroanalytical technique, was used to determine ferric ion diffusion coefficients. The diffusion coefficient decreased dramatically with increasing concentration of iron in solution. An empirical model was used to relate the ferric ion diffusion coefficient to the total amount of sulfate in solution. Measuring the diffusion coefficient dependence on temperature yielded an activation energy of 5.5 kcal/mole of ferric ion. Activity coefficients of ferric ions as a function of concentration were calculated from diffusion coefficient data.

Jan 1, 1981

By C. M. McCulloch

Examination of several coalbeds in Walker County, Ala., Cambria, Greene, and Fayette Counties, Pa., and Raleigh and Wyoming Counties, W. Va., indicates that cleat orientations are similar throughout a vertical sequence of strata. Studies of cleat orientation were carried out in underground mines that are operating in separate coalbeds vertically above one another. The data show that over a vertical separation of 100 to 400 feet, the average difference in coal cleat orientation between mines is 04° for the face and 08° for the butt cleat. Variations of coal cleat direction between coalbeds examined in strip-mined areas show similar values. Cleat orientations measured at outcrops agree well with the directions measured underground, suggesting that the amount of vertical separation between coalbeds has little effect on the resulting differences in cleat directions. The largest variation of cleat directions between adjacent coalbeds occurs where a large horizontal distance separates two sample locations. Cleat orientations for deeper coalbeds are most reliable where the data are taken from directly above.

Jan 1, 1976

By Harold R. Newman

The performance of Ecuador's mineral industry continued to be affected not only by depressed oil prices in recent years but also by natural disasters. In March 1987, Ecuador canceled foreign debt payments for the rest of the year and appealed for international aid because of a series of earth-quakes that destroyed villages and crippled the nation's oil industry. The earthquake destroyed a key section of the country's main oil pipeline and forced a halt to production and shipment of Ecuador's most important export product. Ecuador produces 240,000 barrels of oil per day and exports 144,000 barrels daily. Oil accounts for 60% of the nation's hard currency earnings. The Government of Ecuador asked the Organization of Petroleum Exporting Countries and other oil-producing countries to assume Ecuador's oil sales commitments. Ecuador agreed to pay the countries back in an equivalent amount of oil when it was able to resume exports.

Jan 1, 1989

By Maria I. De Rosa, Charles D. Litton

The U.S. Bureau of Mines conducted experiments for predicting materials' ease of combustion (smoldering onset, smoldering, flaming, and decomposition rates) by means of submicrometer smoke particle characteristics for the development of a simple test method. The experiments were carried out in an approximately 20-L furnace, with a 10-L/min airflow through the furnace for a 14-min duration, at set furnace temperatures of 150°, 250°, and 1,000°C. The variables studied as a function of time were the onset time of smoke particles, time and duration of maximum smoke particle generation, average concentration of smoke particles, and particles' average diameter, mass weight loss, and furnace temperatures. Results show that the onset time of smoke particles is predictive of materials' ease of smoldering, and the time of maximum smoke particle generation and its duration, coupled with mass weight loss, are predictive of materials' ease of smoldering and flaming (depending on the experimental temperatures), and decomposition rates.

Jan 1, 1992

By McHenry Mosier

Although local conditions at each mining property affect the percentage of increase in drilling speed for a given reduction in gage of bit, the results of drilling tests conducted at the Mount Weather testing adit show such a large advantage in favor of the smaller gages that they should be indicative of the possibilities at most mines. GENERAL DISCUSSION Although it is common knowledge among miners that drilling speed ill- creases with reduction in gage of bit, the large amount o this increase is not so universally realized, A recent Bureau of Mines4/ survey of drilling practices in 28 metal mines showed that the maximum gage of starters is 3 inches and that at 50 percent of the mines starters are 2-1/4 inches or larger, Because this size appears too large for conditions at most' mines where abrasion is moderate and where powder distribution permits, the use of smaller bits presents a favorable opportunity for reducing drilling costs.

Jan 1, 1939

By McHenry Mosier

Although local conditions at each mining property affect the percentage of increase in drilling speed for a given reduction in gage of bit, the results of drilling tests conducted at the Mount Weather testing adit show such a large advantage in favor of the smaller gages that they should be indicative of the possibilities at most mines. GENERAL DISCUSSION Although it is common knowledge among miners that drilling speed increases with reduction in gage of bit, the large amount o this increase is not so universally realized, A recent Bureau of Mines4/ survey of drilling practices in 28 metal mines showed that the maximum gage of starters is 3 inches and that at 50 percent of the mines starters are 2-1/4 inches or larger, Because this size appears too large for conditions at most mines where abrasion is moderate and where powder distribution permits, the use of smaller bits presents a favorable opportunity for reducing drilling costs.

Jan 1, 1939

By R. L. Anderson

Mechanical cleaning of bituminous coal in the United States was begun about 1875, with plants in western Pennsylvania and Illinois. The United States Geological Survey began to record the quantity of washed bituminous coal in 1906; and the series was carried forward to 1923, except that no data were collected, for 1922. This statistical work was transferred to the Bureau of Mines in 1925, and the collection of data on mechanical cleaning was resumed in 1927. Data collected before 1927 include only the coal that was washed at the mines and do not include that cleaned by pneumatic methods at the mines and that cleaned at central washeries operated by consumers.2/ The total bituminous coal washed in 1906 was less than 10 million net tons. In 1927, the first year for which complete figures are available for all types of mechanical cleaning, 28 million net tons of bituminous coal were cleaned in the United States.

Jan 1, 1951

By Mark I. Copeland

The Bureau of Mines discovered that silicon and nickel additions can prevent the formation of copper alloys of Sn, Sb, and As on the surface of steel during reheating to hot-working temperatures. When molten, these copper alloys cause surface hot shortness during hot working. Wrought steels were reheated isothermally and by simulated industrial practice; the resulting surfaces were metallographically evaluated. The steels contained, In weight-percent, 0.20 C, 0.45 Mn, and up to 1.00 Si, 1.00 Cu, and 0.15 Ni, and up to 0.30 Sn, Sb, or As. The larger the Cu, Sn, Sb and As content of the steels, the greater the amount of silicon necessary to prevent copper alloy formation. A content of 0.10 Ni considerably decreased the amount of silicon necessary for copper steels containing tin and antimony, but not for those containing arsenic. Theories for the beneficial effect of silicon and nickel additions are presented.

Jan 1, 1975

By Ivette E. Torres

For a study such as this, which summarizes and amalgamates much information collected, compiled, and utilized by the numerous U.S. Bureau of Mines country specialists and branch chiefs for inclusion in their country and regional reports that comprise the five other sections of 1992 Minerals Yearbook-International Review, it is clearly impossible to cite all sources of information used in its presentation, but some recognition is due. Generally speaking, this study and its related detailed studies on countries and areas would be much more difficult, if not impossible to complete, without the efforts of the personnel of our counterpart national mining and geological agencies throughout the world. Information that they collect, compile, and then publish, either in their own volumes or those of central statistical agencies in their countries, are the foundations on which this work rests. Thus, our appreciation is expressed to the multitude of persons employed by these agencies for their contributions.

Jan 1, 1994

By Ralph L. Brown

The chemical properties of the unsaturated members of the aliphatic series of hydrocarbons are such as to render them " made to order" starting points or basic . materials for the synthesis of hundreds of important organic chemicals . The tremendous quantities of these unsaturated compounds that are being produced daily in the various coal carbonization and oil refining processes , and which at present have little value other than that of fuel , render a survey of the identity and ex- tent of occurrence of these compounds important from the viewpoint of economic utilization and resource conservation The increased need of liquid fuel and the relatively early exhaustion of petroleum resources will eventually require every utilization of liquid fuel products obtainable directly or indirectly from coal . Accordingly , the Bureau of Mines took advantage of an opportunity for examining the gaseous unsaturated hydrocarbons found in the gas obtained when a mixture of water- Collection of the material gas tar and coal is distilled in a gas-making retort . for examination was made possible through the courtesy of the Trent Process Corporation , Washington , D.C. , which was at that time carrying on at the Georgetown Gas Works , distillation of " amal gams " prepared from various coals and oils by the Trent process for cleaning coals . Kanawha gas coal ( 70%) and water gas tar ( 30 % ) from the Washington Gas Light plant were used in the " amal gam" being distilled at that time . The results obtained in this examination are presented here .

Feb 2, 1922

By John C. Edwards, Gene F. Friel, John J. Opferman, Robert A. Franks

A series of diesel fuel fire experiments were conducted in the Pittsburgh Research Center's Safety Research Coal Mine (SRCM) to determine products-of-combustion (POC) spread rates along a single entry under zero imposed airflow conditions. Six experiments with an average fire intensity of 330 kW and three experiments with an average fire intensity of 30 kW were conducted in a 1 80 m long entry which had an average 2 m height and 4 m width. POC spread rates were measured by the response time of diffusion type CO detectors, positioned at 30 m intervals, to CO concentrations 5 ppm above ambient. For the 330 kW fires, average POC spread rates of 0.22, 0.13, and 0.06 m/s were determined at 30.60, and 90 m distances from the fire. For the 30 kW fires these average spread rates were reduced to 0.08, 0.04, and 0.04 m/s. The measured maximum roof layer temperature 30 m from two of the 330 kW fire was 30 and 36"C, which is less than the 57°C alarm point of a typical mine thermal sensor. It was determined that smoke detectors can be more effective for mine fire detection than CO detectors. The experimentally determined POC spread rates can be used to provide guidance for specification of sensor spacing to improve early fire detection at zero or very low air flows.

In the last few decades, a considerable amount of effort was directed at accurately determining the coal pillar strength to use for safely designing coal mines. The outcome of this early work was the well known Obert-Duvall, Holland-Gaddy, Bieniawski, and Salamon-Munro equations for coal pillar strength. All of these equations were developed for, and were calibrated with, pillars in a large room-and-pillar area such that the loading could be determined using the "tributary-area" theory. In order to account for the abutment loads associated with full-extraction mining, the empirical methods have typically adopted a simple conceptualization of the abutment load through use of an "abutment angle." Short of a complete numerical or analytical analysis of the coal seam and surrounding strata, very little work has been Fretted toward refining the empirical analysis of pillar loading. It appears that the vast majority of the research has been directed at determining the pillar strength, the numerator of the safety factor equation, when the denominator of the safety factor equation, the pillar loading, plays an equally important role in pillar design. This paper will address the deficit of pillar loading research by exploring the accuracy of the empirical abutment load calculations using insight provided by an elastic overburden model, a laminated overburden model and field observations. Ultimately, it is determined that a constant abutment angle probably over-predicts the abutment load as the mining depth increases.

By S. F. Ravitz, T. M. Romslo

During 1940 and 1941, the Bureau of Mines examined a large number of silver mines in Arizona for their potential as producers of manganese ores. Although very little manganese ore had been produced from these mines, it was generally known that manganese oxides in appreciable amounts were associated with the silver ore. Following the examinations, the Bureau further investigated some of the ore deposits by diamond drilling and other types of sampling. The results of these investigations, from the viewpoint of manganese, were discouraging. However, the investigations did indicate that appreciable tonnages of manganese-silver ores had been left in some of the mines by earlier operators. Most of these ores were too low-grade for direct shipping as ores of manganese or silver, and their beneficiation by ordinary processes was not economic. Exploitation of the ores appeared to be dependent upon the development of a low-cost milling method, which would yield a marketable manganese product and recover a high percentage of the silver. Later, the Bureau of Mines constructed an experimental mill at Salt Lake City, Utah, for the treatment of manganiferous ores by the dithionate process, designed to recover manganese as a high-grade product. The dithionate residues can be treated by other processes for the recovery of additional values that may be present in the ore. This development focused attention on the manganese-silver ores of Arizona and led to setting up Bureau project No. 370, which is the subject of this report.

Jun 1, 1947

By R. H. Lien

The Bureau of Mines, U.S. Department of the Interior, has developed a flue gas desulfurization process as part of its goal of minimizing the undesirable environmental impacts associated with energy and mineral-processing plants. This process, known as the citrate process, involves absorption of sulfur dioxide (SO2) in a buffered solution of citric acid. The S02-loaded solution is regenerated by reaction of the S02 with hydrogen sulfide (H2S) to form elemental sulfur. As an adjunct to the citrate process, bench-scale research has shown that S02-loaded citrate or glycolate solutions can be regenerated by countercurrent contact with steam (stripping) in packed towers. Concentrated S02 is produced by condensing the steam from the stripper product. Thus, steam stripping provides strong S02 gas for liquefaction, sulfuric acid production, or reduction to elemental sulfur. Stripping steam requirements were determined for treatment of 0.25-, 0.50-3 1.0-, and 2.0-pct-S02 waste gases. Steam requirements decreased with increasing S02 concentration n the simulated waste gases. For example, 5 grams of steam per gram o S02 was required to remove 90 pct of the S02 from a simulated copper smelter gas (2.0 pct S02), while 30 grams of steam per gram of S02 was needed for 90 pct S02 removal from a simulated coal-fired powerplant gas (0.25 pct S02).

Jan 1, 1979

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 A. S. Watts

Throughout the Appalachian Mountains there are dikes of coarse granite or pegmatite, which were intruded into other rocks. These pegmatite dikes contain feldspar, quartz, white mica (muscovite), black mica (biotite), and other minerals, such as beryl, garnet, and tourmaline. The investigation here reported has to do only with the dikes of the southern Appalachian region, in which the abundance of each mineral is as in the order given above. The pegmatites of this region are in every stage of alteration from those in which the feldspar is fresh to those in which the feldspar has decomposed to kaolin. The muscovite (white mica) shows no evidence of alteration, although most of the other associated minerals show traces of disintegration where the feldspar is completely kao- linized. At many places mining for mica has been done in dikes in which the feldspar is completely kaolinized, though the only evi- dences of disintegration in the mica are clay stains which are some- times noted between the outside lamina. Mining in these pegmatite dikes antedates history, traces of prehis- toric workings and some crude mining implements of stone having been unearthed by recent operations. The prehistoric mining is generally supposed to have been for mica, although investigations fail to show that the aborigines put the mica obtained to any par- ticular use except for ornaments, a few mica ornaments having been found in mounds in this region. The search for kaolin or semikaolinized feldspar is a plausible ex- planation of these prehistoric workings; all of them were in pegmatite that is more or less altered, and seemingly stopped only when the pegmatite became too hard to permit working with crude stone im- plements. The dumps do not represent the amount of material that one would expect, from their extent, the workings to have produced. The kaolin obtained was doubtless conveyed to the coast and sold to English traders for use in the manufacture of some of the early

Jan 1, 1913

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

6. Computer Simulation of Mine Evacuation Analysis of mine evacuation involves manipulating a large number of interacting variables, such as mine passages, hoist movements, miner position etc. , which makes the problem very difficult to solve without use of a digital computer. Therefore, under this contract, a computer program is written to simulate evacuation of a mine under different configurations. The simulation input variables include characteristics of the mine, expressed in the form of a network of passages, properties of hoists and hoisting strategies, initial miner positions, ventilation and compressed air velocities, stench warning system and self-rescuer capabilities. The simulation can be carried out for cases in which there is no fire, i. e , fire drill simulation, or for cases in which there is a fire at any arbitrary location. The fire is assumed to generate gases which impede movement of miners in the gaseous region. However, the thermal effect of the fire on ventilation or on the miners is not considered. The simulation output includes the evacuation time for each miner, movement of the hoists, propagation of smoke through the mine passages and smoke exposure time of the miners. Details of the mine evacuation program are summarized in Appendices A and B Appendix A describes structure of the program and its capabilities. The flexibility of the program and its suggested uses are demostrated by a number of illustrative examples Appendix B is a user' s manual for the program which includes instructions for program use and explanation of the logic employed in the program. A computer listing and printout of a typical output are also included in the Appendix B The ten illustrative examples summarized in Section A 4 (Appendix A) provide proof of validity of the program and help make certain inferences about mine evacuation. The first example, which is simulation of an actual mine fire drill conducted in a mine, has predicted evacuation time within 5 percent of the actual evacuation time in the fire drill, demonstrating thereby, the ability of the program to make accurate predictions.

Jan 1, 1976

By D. Harrington

"The fire boss in coal mining and the shift boss in metal mining, though held responsible to a large extent for safety of underground employees and of the mine, are, it seems to me, not always vested with sufficient authority nor given compensation commensurate with their duties. The metal-mine shift boss, although his position as regards his relations between employer and employee, is frequently an unenviable one, has as a rule much more authority than the fire boss and is not expected to perform the menial tasks required of the latter by many coal-mining companies.In most coal-mining States the coal-mine foreman and the fire boss are re¬quired to possess a certificate of competency obtained by passing an examination. The foreman is legally responsible for the safety of the miners, as in most instances the superintendent is not required to pass an examination. Although the foreman is held legally responsible for the safety of the miners, the law does not, in general, compel the superintendent or other higher officials to delegate sufficient authority to the foreman to enable him to put his wishes or judgment into effect; and this condition has tended in many instances towards perpetuation of unsafe conditions.The fire boss is held legally responsible for conditions in his ""beat"", but he is generally given only such authority as the mine foreman sees fit to delegate, frequently very little, Moreover, the fire boss is generally required to cover his ""beat"" within two hours before the entrance of the underground workers. Only too often his territory is so great that in order to reach all the working faces and chalk the required date at the face, he must travel at a rapid walk or even run. When such haste is necessary to cover the required ground, it is manifestly im¬possible for the fire boss to make a careful inspection or examination of the roof, timbering, wiring, gas, etc., at each place, and doubtless in his hurry many unsafe conditions escape his notice."

Sep 1, 1920

By W. E. Miller, John Campbell, W. P. Yant, G. W. Jones

"Because of its interest in accident prevention, the U.S. Bureau of Mines cooperates with city officials and utilities in investigating the causes of explosions in sewers, manholes, and other underground openings and in developing means for preventing such explosions. For several years this Bureau has been cooperating with the Edison Electric Illuminating Co. of Boston and the Boston Consolidated Gas Co. in detecting and eliminating combustibles and physiologically harmful gases in manholes in the city of Boston and adjacent territory.These Bureau of Mines investigations° have shown that combustible gases from the usual sources — leakage from gas—distributing systems and from underground tanks and gasoline wastes — can be located and the dangerous conditions remedied by a well—planned, adequately supervised, systematic, and continuous manhole survey. However, other types of gas, which are termed here ""soil"" gases, also occur in manholes and are more difficult to eliminate because they have no fixed origin and because seasonal and barometric changes affect their production and passage into the manhole space. These gases appear to be produced by bacterial and fermentation or through reactions of entrapped air in the soil. Soil usually abnormally high in carbon dioxide and low in oxygen, and contain varying amounts of methane. They are especially clangorous to men entering manholes because they lack sufficient oxygen to support life. Owing to the difficulty of constructing gastight manholes the most feasible method for eliminating soil gases from manholes is by ventilation. Consequently the Bureau of Mines initiate 4 study of natural ventilation methods for the removal of these gases from manholes and also for taking care of unforeseen accumulations of combustible gases and vapors.The following factors were considered by the Bureau to be important to the natural ventilation of manholes: (1) Relation of area of ventilation opening* to the capacity of the manholes, (2) size and shape of the manhole, (3) design of the ventilation opening (4) and velocity, and (5) weather conditions."

Jun 1, 1936