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By David K. Ingram

Research performed by the U.S. insurance industry has determined that mine subsidence is uninsurable. Consequently, the insurance industry has decided not to voluntarily offer mine subsidence insurance. The U.S. Department of the Interior has long been investigating the effects of mine subsidence. These investigations have resulted in Federal regulations and controls of mine subsidence. This U.S. Bureau of Mines report generally describes mine subsidence, the development of mine subsidence insurance programs, and the eight current mine subsidence insurance programs in the United States. The States that have these subsidence programs include Colorado, Illinois, Indiana, Kentucky, Ohio, Pennsylvania, West Virginia, and Wyoming. Major aspects of the programs include history, administrative and operational procedures, insurable structures, recognition of mine subsidence, major exclusions, claims, insurance premiums, and the economic health of each program. Addresses of agencies involved with mine subsidence insurance are also given. Information within this report can be useful for residential and commercial property owners and mine operators. States that are considering starting or have an existing mine subsidence insurance program can also use this report as a model for initiating or modifying their programs.

Jan 1, 1993

By J. J. Shields

This is the Seventh of a series of publications that describe methods and practices used in mining bituminous coal mechanically.3/ This report deals with the operation referred to in coal mining as continuous mining, and the interest shown by mining companies in this method is the reason for this study. Only continuous mining as it applies to the room-and-pillar system of mining, or a modification thereon, is discussed in detail in this report. Although not always as continuous as the name implies, it is a system of mining in which a machine is used to cut and load coal in one continuous operation without drilling and blasting the coal. With the mining equipment in most general use today, the usual cycle of operation in mining of coal is: (1) Timber, (2) cut, (3) drill, (4) blast, and (5) load. As the phases of this type cycle cannot be performed simultaneously in the same working place, it is necessary to operate from 3 to 7 working places so that at least 1 place is available for coal loading at all times. Even if the schedule of the phases in a cycle is maintained, coal production ceases during the time required to move the loading equipment from one loading place to the next. In 1920 a continuous-type mining machine4/ was installed in an Illinois coal mine to drive entries. Several other companies used these entry drivers for short periods in the following few years. In 1927 a southern Illinois coal company installed 2 of these machines which, in the next 25 years, were reported to have driven over 200 miles of entries. The machines did not attain widespread usage.

Jan 1, 1954

By S. K. Ash

In arriving at economic losses in coal mining due to accidents, a statistician is confronted with many difficulties on account of the lack of information relative to nonfatal accidents. For comparative purposes the ex¬ perience of those countries, States, or companies that keep complete records can be drawn upon and an extimate can be arrived at whereby one State can be compared with another, or one mine compared with another in the same district. Such a comparison for the United States has been compiled by the United States Bureau of Mines. It will be observed in Table 1 that the cost per ton for accidents in the State of Washington for the year 1927 is higher than for any other State, with the exception of Georgia and North Carolina, with a small combined tonnage of 130,089 tons. (The figures for coal production in Table 1 are taken from Bulletin 319, 1930, of the United States Bureau of Mines.) The reasons why the cost of accidents in Washington might be higher than the average are on account of physical conditions such as steep pitches, faults, igneous intrusions, highly explosive coal-dust, extremely friable coals, presence of gravel and water, very gassy coal beds, rugged topographic conditions, inherently bad roof and floor, thick beds, and heavy cover. The nature of the coal beds requires the use of preparation machinery. The mines are often deep, and topographic conditions are such that long and fast haul¬ age becomes necessary. All of these factors not only tend to cause high cost of production, which is manifested largely in a. lower than average daily pro¬ duction, per man, but..they.also affect to some degree a tendency toward a higher than average cost for accidents.

Nov 1, 1931

By N. E. Hanna

Originally developed for use in coal mines where on-shift blasting with explosives was prohibited, compressed-air blasting has been used for the past 15 years as a substitute for fixed explosives. With the current commercially available compressed-air systems -Airdox and Armstrong -coal is dislodged by a high-pressure discharge of air from a pressurized shell placed in the coal borehole. In the original systems stationary compressors were mounted on the surface or in the underground ventilated areas. These proved so successful that a mobile compressor unit was developed for use at the working face. Because of the possibility that such a unit might operate in a gassy atmosphere, the Bureau of Mines has investigated the hazards associated with operation under conditions where firedamp could accumulate in explosive concentrations. ACKNOWLEDGMENTS Grateful acknowledgment is made of cooperation of C. E. Carter, H. R. Hiller, R. E. Kennedy, H. Kohn, H. D. Metzinger, J. Mahoney, J. Nickovich, G. So Scott and I. Spolan in the experimental work.

Jan 1, 1956

By W. L. Staker

The Bureau of Mines investigated the use of shredded automobile scrap for copper cementation. Air agitation was used to improve the cementation rate and prevent excessive buildup of copper on the iron. The pieces of scrap were too large to be properly evaluated in the laboratory; therefore, a pilot scale test unit was constructed and the process tested at field locations. Pregnant solution was obtained from industrial leaching operations, processed in the test unit and the barren solution and cement copper were returned to the plant process stream. The test results showed that the air-agitated launder containing auto-mobile scrap was an effective means for recovering copper from leach solutions. A continuous l4-day test run was made without a noticeable decrease in cementation efficiency. The most suitable scrap product was obtained from incinerated automobile hulks shredded in a hammer type of shredder. However, it was necessary to remove small pieces such as nuts and bolts because they interfered with the discharge of the copper product.

Jan 1, 1976

By Jr. Hazen

Two statistical techniques, the mean-square-successive-difference test and correlation, are used to investigate the problem of assigning an area of influence to an assay. Data from five hydrothermal deposits, Climax molybdenum, Cebolla Creek titaniferous iron, San Manuel copper, Piedra Hueca copper, and Butte copper, are studied. Two groupings of the assays are used for the mean-square-successive-difference tests. One group involves an increasing sample volume by reaveraging assays to represent a longer sample intervals, the other by regrouping assays to represent longer sample intervals without a change in sample volume.

Jan 1, 1967

By Carl Rampacek, W. A. McKinney

The feasibility of leaching calcareous and siliceous oxidized copper ores by downward percolation with dilute acid was investigated in the laboratory and in a small continuous plant operated by the Federal Bureau of Mines . The crushed ore was leached in deep columns with solutions containing 1 or 5 percent sulfuric acid to dissolve the oxidized copper . Bench - scale laboratory tests on two calcareous ores from the same deposit indicated that a maximum copper extraction , about 72 percent , could be expected from heap leaching a feed as coarse as 1 inch . Laboratory tests on a siliceous ore showed that almost 70 percent of the copper could be extracted by leaching a 1 / 4 - inch feed . The bench - scale tests were supplemented by larger continuous runs wherein the copper was recovered from the leach liquors by precipitation on detinned scrap iron . Leaching the calcareous ore for approximately 10 days recovered 62 percent of the total copper . The sulfuric acid consumption was 9.6 pounds per pound of copper recovered . Treatment of the siliceous ore recovered 62.5 percent of the total copper in a 2.5 - day leach and the acid consumption was 3.7 pounds per pound of copper recovered . Cement copper products that assayed over 71 percent copper were obtained from the leach solutions by precipitation on scrap iron . The bench - scale and continuous tests demonstrated that downward percolation leaching of the calcareous ores was technically feasible but not economically practicable because of high acid consumption by the gangue . Leaching of the siliceous ore was rapid and the acid and water requirements were nominal . The downward percolation leach procedure is simple and requires a minimum of plant equipment .

Jul 1, 1960

By B. J. Moore

This publication contains routine analyses and related source data for 419 natural gas samples from 22 States collected during calendar year 1964 as part of a continuous survey of the United States for occurrences of helium in natural gas. This survey has been conducted by the Bureau of Mines since 1917. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus, which are described in Bureau of Mines Bulletins 4863/ and 576.4/ Six previous publications have been made to present the results of 6,293 gas analyses made by the Bureau of Mines, Helium Activity, prior to 1964. The first three, Bulletins 486,5/ 576,6/ and 617,7/ contain analyses and related source data on 5,214 gas samples collected from

Jan 1, 1966

By H. F. Yancey

Although a general relationship exists between the two criteria used to measure sharpness of separation -error area and probable error -they sometimes give quite different appraisals of a particular washing operation. Error area takes into account how the entire raw coal was treated, whereas probable error reflects only how the material of intermediate density was separated, ignoring completely the recovery of clean coal and the rejection of heavy impurity. Error area is thus more reliable for general use. In heavy-medium cleaning, sharpness of separation decreases with increase in separating density, but ordinarily the change is not great enough to affect the yield and ash content of washed coal measurably. Therefore, distribution curves for heavy-medium units can be transposed from one separating density to another, at least in the range of separating densities ordinarily used in the United States.

Jan 1, 1955

By H. W. Kilau

The Bureau of Mines evaluated synthetic fluorspar as a substitute for natural fluorspar flux in basic cupola ironmaking. The synthetic fluor-spars tested were prepared from waste fluosilicic acid generated during the processing of fluorapatite ore. The cupola trials showed the synthetic products to be the equivalent of natural fluorspar from an operational standpoint. However, wet scrubber sampling showed that substantial losses of volatilized fluorine occurred from the cupola during operation. The losses during synthetic fluorspar trials considerably exceeded those from natural fluorspar trials. Laboratory viscosity testing, using a high-temperature rotational viscometer, confirmed this finding and indicated that fluorspar volatility in slags is related to slag basicity. Synthetic fluorspar is accordingly recommended more for highly basic cupola operation (>1.3 basicity) than for neutral or acid operation, because of the increased potential for pollution and baghouse filter detezioration"

Jan 1, 1989

By William M. Thornton

[Owing to the comparatively high freezing point of nitroglycerin (14, 15, 16, 17, 18, 23, 37, 38)3/ - 1.9° C. and 13.0° C. for the labile and stabile modifications, respectively, as determined by Hibbert (16) - manufacturers of dynamites have incorporated into the liquid portion of these composite explosives various substances capable of participating in an explosion, to depress the above-mentioned freezing point. Aromatic nitro-compounds, chiefly nitrobenzenes, nitrotoluenes, and nitronaphthalenes, have been used to a considerable extent (11), but such nitrosubstitution products have not proved altogether satisfactory, as has been shown clearly by Naoúm. (14). Consequently there has been a strong tendency in recent years to replace them with one or more of several nitric esters, among which the following (29, 35) have been prominent: Dinitrochlorhydrin (monochlorhydrin dinitrate); nitrosugars, for example, sucrose octanitrate (19); tetranitrodiglycerin (diglycerin tetranitrate); nitroglycol (ethyleneglycol dinitrate); and diethyleneglycol dinitrate (13, 46, 47). Of these, nitroglycol (33, 4l, 45, 48, 49, 65) is outstanding in importance. As the Bureau of fines is naturally interested in the analytical chemistry of the "explosive oils," it seemed desirable to bring together in this report the widely scattered experimental work covering the problem of differentiation that has appeared in various chemical and physicochemical publications.]

Jan 1, 1941

By G. S. Scott, G. W. Jones

"INTRODUCTION An important phase of the accident-preventing program of the Bureau Mines is the determination of the explosion hazards of various combustible gases, vapors, and liquids encountered in mining and allied industries and the development of methods of eliminating or mitigating them.Recently, isobutane has become a commercially important raw material in the production of aviation gasoline by the alkylation process. 4/ in which isoparaffins are combined with olefins to give higher molecular weight compounds of branched-chain structure.Because of the anticipated commercial importance of isobutane in industry, it has been deemed necessary to study and determine its general explosion haz¬ards. This report gives its limits of inflammability, minimum ignition temper¬atures, and the amounts of nitrogen and carbon dioxide required to render isobutane-air mixtures noninflammable."

Jun 1, 1947

By L. M. Adams

Experiments in reclaiming acidic surface-mined coal lands with raw fly ash from bituminous-coal-fired powerplants were conducted by the Bureau of Mines at two sites in northern West Virginia. Plots at both sites were treated with varying tonnages of fly ash from three area powerplants and were planted with a variety of grasses, legumes, trees, and shrubs. Eight grasses and seven legumes were investigated. Greatest promise for growth under harsh soil conditions was shown by Kentucky 31 fescue, rye and red top grasses, and birdsfoot trefoil, a legume. Survival of trees and shrubs was negligible. Addition of fly ash to the spoil increased the pH to a range tolerable to some types of plant growth, improved the texture of the soil, and increased the available water of the resulting mixture.

Jan 1, 1971

By M. M. Fine

Small-scale laboratory mineral-dressing studies were made on a total of nine individual or composite samples of manganese-bearing material from the west-central Arkansas, or Mena, district. Of these, only three yielded concentrates that would probably be acceptable for purchases by the Federal Government fur the National Stockpile. Concentrates from some of the other properties, however, contained more than 40 percent Mn and might be merchantable to other purchasers of manganese ore. In most instances, a too-intimate association of manganese oxides and gangue is conducive to low grade, low recovery, or both, so that mechanical concentration processes do not promise much for this district.

Jan 1, 1956

By IRENE AITKENS

The emerald is the most costly of all gems , due to the scarcity of flawless stones . This fact gave rise to the ancient axiom , " As rare as an emerald without a flaw . The finer gems not only command the highest prices at all times , but when flawless are considered the most highly prized of all gem stones . George F. Kunz divides emeralds into two distinct classes : " Exceptional specimens , " which bring as much as $ 6,000 a carat ; and " fine- quality specimens , " which bring about $ 1,000 a carat .

Jul 1, 1931

By J. R. Thoenen

The objective of this circular is threefold: First, to describe briefly the various modes of occurrence of sand and gravel. Second, to emphasize the need for adequate prospect¬ ing and exploration prior to the expenditure of funds for development and plant construction. Third, to describe various methods of prospecting and exploration and their application to the several modes of occurrence of sand and gravel. Sand and gravel may be found in nearly every county or township in the United States. Commercial deposits, however, are by no means so widespread. The introduction of concrete and the consequent impetus given to consumption of gravel and sand aggregates has seriously depleted deposits in some congested areas. Increasing re¬ strictions in the specification requirements for marketing sands and gravels have further narrowed the economic areas. On the other hand, the combination of increasing transportation costs and decreasing selling prices has forced the decentralization of gravel production. As a result smaller, intermittently operated, and widely scattered portable or semiportable unit plants have been encroaching on the territory formerly supplied from centrally located pits with large tr.atment plants. Generally speaking, the small portable plant can not produce any great variety of ma¬ terials to as exacting specifications nor as economically as the large permanent plant.

Dec 1, 1932

By Wilford S. Wright, Harold E. Heide, Robert S. Sanford

"INTRODUCTION The United States production of tin has always been negligible, and domestic requirements have been met almost entirely by imports. The advent of war in Europe in 1939 brought a threat to our foreign source of supply, and steps were taken by Congress to forestall shortages of tin and other metals. By authority of the Strategic Minerals Act, passed by Congress in 1939, the Bureau of Mines and Geological Survey conducted investigations of domestic tin deposits.An examination of Alaska deposits was undertaken in 1940 and 1941 by J. B. Mertie, Jr., and Robert R. Coats of the Geological Survey.H. B. Heide conducted a preliminary examination of lode and placer-tin deposits at Cape Mountain in 1942, which was followed in 1943 and 1944 by a program of exploration by churn drilling in the placer area and trenching and sampling the lode deposits.Placer tin, found at the head of Goodwin Gulch, Cape Creek, First Chance Creek, and Boulder Creek, indicates that the mineral was derived from the vicinity of lode cassiterite occurrences on Cape Mountain. Placer tin led to the discovery of at least one, cassiterite vein by the Geological Survey and the Bureau of Mines."

Dec 1, 1946

By H. A. Doerner

From thermodynamic calculations3 Maier predicted that zinc oxide Land methane would react at specified temperatures substantially according to equation (1). (1) ZnO + CH; = Zn (gas) + CO + 2H2 Other reactions that may take place are: (2) CH4 = C + 2H2. (3) ZnO + CO = Zn (gas) + CO2 (4) ZnO + H 2 = Zn (gas) + H2O . Maier predicted that 870°C. would be the critical temperature above which reaction (1) would take precedence over reaction (2) and that reaction (1), at equilibrium, would be substantially complete at or above 927°C.

Jan 1, 1931

By Donald F. Smith

This report describes the construction and calibration of two ice calorimeters and includes results of high-temperature heat-content measurements, made by the Federal Bureau of Mines, on rubidium fluoride, hafnium tetrafluoride, cesium chloride, and cesium iodide. The heats and entropies of fusion of rubidium fluoride, cesium chloride, and cesium iodide have been calculated at their respective melting points using equations derived from the experimental heat-content data. Hafnium tetrafluoride did not melt within the range of temperatures investigated. Heat and entropy of transition of cesium chloride from the alpha to the beta form were also determined. INTRODUCTION Free-energy data usually afford the cheapest and quickest means of determining the feasibility of experimentally untested reactions. For known reactions, free-energy data show the variation of the equilibrium constant with temperature and make it possible to calculate, without experiment, the maximum ratio of product to raw material for a given chemical process.

Jan 1, 1961

By George L. Gates

This report presents is an evaluation by the Federal Bureau of Mines of the effect of clay-water, brine, and oil-base drilling fluids on the productivity of test wells drilled on the Umiat anticline in U.S. Naval Petroleum Reserve No. 4 in northern Alaska. Eleven, wells were drilled on the Umiat structure as part of the U.S. Navy's extensive exploration of the Reserve during 1944-53 to determine the possibilities for oil production. The Federal Geological Survey cooperated in the exploration program and has published a comprehensive report3/ on the geology of the area and case histories of the wells. The re¬port also includes the results of special studies by the Bureau in connection with the drilling and coring of well 9 with oil-base mud in hole and was the source of much of the information used in preparing this publication. Of the eleven wells, four were drilled with rotary tools and water-base mud (one of the water-base muds was an oil-in-water emulsion mud), five were drilled with cable tools with brine in the hole, one was drilled with cable tools with brine in the hole and later reamed with rotary tools and crude oil, and one was drilled with rotary tools and oil-base mud. Although all of the wells penetrated sandstones that contained oil and gas, some were productive and others were not. The latter two wells, one completed with crude oil in the hole (with some added brine) and the other with oil-base mud, had the greatest productive capacities. The wells drilled with cable tools and brine in the hole had lower productive capacities. In contrast, two of three wells completed with rotary methods and fresh-water drilling mud and the well com¬pleted with rotary and emulsion mud were unproductive.

Jan 1, 1960