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By T. F. Tomb

Past experience has shown that the penetration characteristics of the 10-mm nylon cyclone used on approved personal sampling equipment are significantly different from those determined in the laboratory using a nonpulsating flow source. The Bureau of Mines has developed and recommended a modification to presently approved equipment that will alleviate this difference. However, as a result of this modification, a new relationship for converting respirable dust concentrations measured with approved personal sampling equipment to equivalent concentrations as measured with an MRE instrument will have to be established. This Bureau of Mines report describes the underground sampling program conducted to establish a new factor for converting respirable dust concentrations measured with personal sampling equipment, modified with a recommended pulsation damping device, to an equivalent concentration as measured with an MRE gravimetric dust sampler.

Jan 1, 1973

By Oliver Bowles

The United States has never attained importance as a producer of asbestos, the domestic output being only 1 to 3 percent of the quantity required to supply raw material for its extensive asbestos-product manu- facturing industries. Production is centered in four principal countries-- Canada, Rhodesia, Union of South Africa, and the Soviet Union. Since asbestos first became an important commercial commodity the Province of Quebec, Canada, has led in tonnage produced, but a large proportion of the output of this province is shorter, nonspinning grades. Since 1916 the Union of South Africa and Rhodesia have become increasingly important as sources of the higher-grade spinning fibers. Before the World War Russia ranked next to Canada as a producer of asbestos, but during the revolution- ary period the industry in that country was almost at a standstill. In 1926, however, activity was revived, and each year since then production and exports have increased greatly. Minor quantities of asbestos are produced in Cyprus; Australia, Finland, and several other countries. Chrysotile is the leading product in all the producing countries, but substantial quantities of both blue (crocidolite) and brown (amosite) asbestos also are produced in the Union of South Africa. Minor quantities of anthophyllite and similar amphibole varieties are mined in the United States, Italy, Bulgaria, Finland, and several other countries.

Jun 1, 1934

By David W. Houseknecht

Probabilities of encountering coalbed discontinuities during vertical or horizontal drilling in a specific coalbed can be estimated based on analysis of mined-out areas of the coalbed where the size, shape, orientation, and distribution of discontinuities are known. The result- ant probability estimates can be applied to cost-risk evaluations of drilling programs proposed for exploratory, developmental, or methane drainage purposes in undeveloped areas of that coalbed. Data compiled from mine maps of the Beckley Coalbed in southern West Virginia were used to estimate the probabilities that discontinuities would be encountered in two illustrative hypothetical drilling programs--one for drilling vertical boreholes and the other for drilling horizontal boreholes. Analysis based on a mined-out area of the Beckley Coalbed indicated that vertical methane drainage boreholes spaced 1,000 feet apart in a square grid pattern would each have a 29 percent probability of encountering a discontinuity in a geologically unexplored area of the coalbed. It was also determined that exploratory vertical drilling could locate most of the discontinuities if a borehole spacing of 2,500 feet were used. For horizontal drainage boreholes in the Beck- ley Coalbed, the analysis indicated a linear relationship between hole length and the probability of encountering a discontinuity.

Jan 1, 1982

By J. M. Singer

Quenching distances for flames of methane-coal dust mixtures were determined with air and oxygen-enriched air. Coals used were Pittsburgh, Sewell, and Pocahontas No.3. Quenching distances were greater for flames of hybrid mixtures of coal dust and methane than for methane flames of corresponding stoichiometry. From the data of quenching distances and methane-coal dust concentrations was calculated the quenching equivalence, which is the increase in coal dust concentration required to maintain a given quenching distance value as the methane concentration decreases. These equivalences could be useful in identifying hazardous methane-coal dust mixtures in mines.

Jan 1, 1966

By R. T. Johansen, R. J. Heemstra

In water flooding the gradual accumulation of insoluble materials on the sand face causes the injection pressures to increase while decreasing the amount of water injected . This plugging material often is composed primarily of insoluble precipitates of calcium , iron , and magnesium . Treatment with sodium tripolyphosphate ( STP ) either eliminates or reduces the formation of precipitates . Field tests are discussed showing the almost immediate effects of using STP in the injection water . Methods of treatment , solubility of STP in fresh water and brines , and precautions to observe when starting to treat a waterflood with this chemical are given . Laboratory data show that the preferential wettability of a crude oil for reservoir rock can be reversed by adding a small amount of STP to the flooding water . This reversal in wetting tendency should not only decrease the injection pressures but also increase oil recovery by improving the sweep efficiency of a water flood .

Jan 1, 1964

By Edward J. Murphy

A comparative study has been made by the Bureau of Mines of several analytical methods for determining carbon monoxide and nitrogen oxides in toxic gases produced by the detonation of explosives. Laboratory and field methods and detector-tube devices are described. Analytical results are compared, and reliability of the various methods is discussed. INTRODUCTION In all underground mining there is ever-present danger to persons from possible overexposure to carbon monoxide and nitrogen oxides created by explosives or blasting agents. These health hazards, recognized for many years, led to the early establishment by the Bureau of Mines of specific requirements regarding fumes generated by explosives authorized for use in underground coal mines in the United States.3

Jan 1, 1961

By Michael J. Magyar

The Federal Bureau of Mines has developed a hydrametallurgical method to recover aluminum, aluminum oxide, and fluxing salts from aluminum salt slags. The slag is leached with water at room temperature to produce a saturated brine slurry. Screening of the slurry yields an aluminum-rich fraction that can be returned to the dross furnace. The remaining slurry is vacuum filtered, yielding a clear brine solution and an aluminum oxide filter cake. Evaporation of the clear filtrate produces a high-purity fluxing salt for reuse in the dross furnace. Over 80 pct of the metallic aluminum is recovered in the aluminum-rich oversize fraction, while essentially all the fluxing salts are recovered by evaporation. This report contains the final results of an investigation on a process research unit scale, an economic evaluation of the method, and recommendations to further improve the process.

Jan 1, 1979

By B. W. Jong

As part of the Bureau of Mines program to develop substitutes for critical and strategic materials for metallurgical applications, the Tuscaloosa Research Center has evaluated the effect of additives and starting materials on the sintering and strength properties of sialon (silicon-aluminum-oxynitride) compositions fabricated by conventional pressing and sintering techniques. Sintering and MOR (modulus of rupture) data were developed for sialon compositions produced from three components, Si3N4, A1203, and AIN. When doped with Y203 to aid in sintering, the highest MOR values were obtained with compositions containing between 20 and 30 mole-pet (A1203 + AIN). The effect of the crystalline phase of the Si3N4 and Al203 used in the three-component system on MOR also was investigated. Alpha-Si3N4 and ?-A1203 were found to be the best starting materials. A sialon composed of 67.4 mole-pct a-Si3N4 plus 32.6 mole-pct (?-AI203 + AIN), doped with 5 wt pct Y203, had MOR values at 25°, 1,200°, and 1,400° C of 40,300, 40,300, and 31,100 psi, respectively. Samples of this composition doped with Gd203, MgO, Zr02, and ZrSi04 also were evaluated. The ZrSi04-doped sialon had higher MOR values than Gd203-, MgO-, and Zr02-doped materials but lower MOR values than the Y203-doped sialon. The MOR values of ZrSi04-doped sialons were 25,000 and 25,900 psi, respectively, at 25° and 1,400° C.

Jan 1, 1981

By Joseph E. Matta

The Bureau of Mines conducted a field study to investigate thin suppression of respirable dust by water sprays on a continuous-mining machine. Determining the importance of the top and bottom sprays for two types of spray nozzles was emphasized. Results showed, at a 90-pct confidence level, that (1) at least 70 pct of the dust was generated during the sump cut, even though nearly half of the coal was mined during the downshear operation, (2) the water sprays on the top of the boom had little effect in suppressing respirable dust, and (3) B.D. 5 spray nozzles mounted beneath the boom reduced dust at least 33 pet more than B.D. 5 sprays mounted on top of the boom. A single-cut technique was developed that gave good reproducibility for replicate cuts (coefficient of variation of 20 pct).

Jan 1, 1976

By J. W. Town

The Bureau of Mines conducted phosphate beneficiation studies to determine the influence of mineralogical and textural features on the recovery of phosphate from select bed and composite samples representing different phosphate rock types of the western Phosphoria Formation. Batch heavy-liquid tests showed that ore grade) pellet size, and type of interstitial material were significant parameters affecting concentrate grade and recovery. Recoveries at acid grade (31.5 percent P2O5) ranged from 98 to 56 percent. Liberation was essentially complete at 28 mesh, and recoveries tended to drop when overgrinding occurred.

Jan 1, 1966

By R. V. Lundquist, H. Leitch

Sodium aluminate is the principal aluminum compound formed in the sinters prepared by the lime - soda sinter process for recovering aluminum from silicate source materials . The properties and characteristics of this compound were studied to improve the efficiency of the process . Crystalline sodium aluminate was prepared by sintering stoichiometric quantities of soda ash and calcined alumina for 1 hour at 1,250 ° C. The extent of aluminum extraction from sodium aluminate was determined in water and in solutions of NaOH and Na₂ CO3 . Nearly complete extraction of aluminum from sodium aluminate was achieved only in solutions containing free NaOH in excess of that supplied by the salt through hydrolysis . About 42.2 to 68.8 percent of the aluminum was extracted in water or in solutions of Na₂ CO . The precipitation of alumina trihydrate from sodium aluminate solutions was shown to be part of a continuous , reversible reaction according to the equation Al (OH ) A1 (OH )3 + OHThe reverse reaction dissolves alumina trihydrate in NaOH solutions to produce sodium aluminate . Approximate equilibrium concentrations were determined for the reaction at 30° , 50 ° , and 70 ° C. False apparent equilibrium conditions for the dissolution reaction appear when only a small excess of alumina trihydrate is present in the NaOH solutions . A large excess of alumina trihydrate must be present before the true equilibrium point is assured . The engineering significance of the data is summarized , showing controls that should be exercised for a successful and efficient process .

Jan 1, 1964

By W. H. Young

The thickness of the coal seam is one of the more important items influencing the productivity and general overall efficiency of operation of a coal mine. The average thickness of coal seams mined in the United States has changed very little in the past 40 years. The first measurement of thickness of bituminous coal and lignite seams was made for 1920, when the average thickness was 5.3 feet.2 The average thickness for later years was as follows: 1945, 5.4 feet; 1950, 5.3 feet; 1955, 5.2 feet; 1960, 5.3 feet; and 1965, 5.2 feet.3 Table 1 includes data on number and production of bituminous coal and lignite mines classified by 1-foot intervals of seam thickness mined in 1920, 1945, 1950, 1955, 1960, and 1965. Though bituminous coal and lignite are mined today from seams of exceedingly variable thickness--less than 2 feet to more than 50 feet--a large majority of the production, 62 percent in 1965, came from seams 3 to 6 feet thick. This is not surprising since the coal seam of moderate thickness presents the least mining difficulties.

Jan 1, 1967

By E. P. Youngman

This paper is one of a series of digests of foreign mining legislation and court decisions that is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries . This interpretation of the mining laws of French Indo - China is a translation of an article published by the Department of Mines of Indo - China ; 4 and it is released subject to correction and amplification by the proper American foreign- service officers .

Mar 1, 1933

By R. M. Santmyers

Umber and sienna, like ocher, are naturally occurring mineral pig- ments composed largely of clay permeated with hydrated iron (ferric oxide), but they differ from ocher in that they also contain hydrated manganese oxide. The presence of manganese accounts for their browner color. In addition to silica and alumina (clay) and the coloring oxides of iron and manganese, these pigments often contain lime, barium, and other metallic salts as impurities. Sienna most nearly approaches ocher in chemical composition, and the chief distinction is its physical character. It grades into ocher with de- creasing iron content and into umber with increasing manganese content. Sienna is translucent rather than opaque and is more of a stain than a pigment; as the iron oxide content is rather high (often 60 to 80 per cent), the color is strong and rich and varies from pure brown to reddish brown. This pigment raw sienna, terra di Siena, and Italian earth. is known under several names: Burnt sienna is a pigment of an orange-brown tint made by cautionsly calcining raw sienna. It is divided into two grades; American, and Italian burnt sienna. American burnt sienna is a reddish-brown pigment containing from 25 to 60 per cent iron oxide (Fe2O3). One grade, found in Pennsylvania, analyses as high as 80 per cent and is mown as double strength sienna. Italian burnt sienna is a pigment generally containing more iron than the American product, averaging 60 to 75 per cent iron oxide.3 American pig- ments of the same iron content differ materially in shade, having a Havana- brown color, whereas the Italian is more of a maroon. Italian siennas when tinted with 20 per cent of white, show a bluish tint, whereas American siennas yield a brownish or yellowish hue. Raw umber, also known as Turkey umber, Levant umber, and terra ombra, is a greenish to yellowish brown siliceous and ferruginous earth, containing a considerable proportion of one or other of the higher oxides of manganese, Mng04 and MnO2." It is similar in many respects to raw sienna except that it is much coarser and contains more manganese oxide. All umbers contain over 5 per cent of manganese dioxide. Like sienna, umber is a permanent pigment, not being injured by light or by impure atmospheres. Burnt umber (velvet brown, chestnut brown, etc.), results from the calcination of raw umber. The color is much richer and warmer than that of the raw umber. The colors are equally permanent and can be used in conjunc- tion with all other durable pigments.

Sep 1, 1931

By G. E. Rennick

A siphon-type laboratory airlift well was designed and operated by the Bureau of Mines to study the concurrent flow of air and oil in small-diameter pipes. Glass flowstrings ranging from to 1 inch in diameter and from L4 to 64 feet in length were equipped with various-sized air-entry jets. Liquid holdup volumes were used to correlate vertical-flow data, and empirical equations for computing gas requirements were derived. The effect of flowstring length on flow efficiency, oil- and gas-production rates, and gas-oil ratios was relatively minor at all flowing pressures. Air-jet sizes and flowstring diameters, however, had a marked effect on flow efficiency and oil- and gas-production rates. The small air-jet sizes increased maximum flow efficiency and its associated flowing pressures but decreased oil- and gas-production rates. An increase in flowstring diameter increased maximum flow efficiency with its associated flowing pressure and also increased the production rates of oil and gas.

Jan 1, 1965

By A. L. Engel

High extractions of lead, gold, and silver resulted from treatment of an oxidized, arsenical refractory ore by chloride volatilization. The ore was roasted in an oxidizing atmosphere at 1,000° C. for 1 hour. The chloridizing reagent was 300 pounds of CaC12?2H20 per ton of ore. Ninety-nine percent of the lead, 98 percent of the gold, and 96 percent of the silver, and only 6 percent of the arsenic, were volatilized. These results indicated that a satisfactory method could be developed for treating this type of ore. Recovery and separation of the volatilized values and developing metallurgical and operating data for this process require further investigation on a more extensive scale. Tests by gravity concentration, flotation, and cyanide leaching did not give satisfactory results.

Jan 1, 1958

By C. N. Rosenecker

The power required to circulate a gas-solids suspension was determined using a centrifugal compressor and a closed system. The suspension consisted of 18- to 40-micron glass beads in a mixture of 89 percent N2 and 11 percent CO2 at 20 psig. Solids-to-gas (S/G) ratios w re O to 2.2 lb/lb; gas flow rates were l.2 to 2.5 lb/min. Power requirement was found to follow the relationship hp t = hp(. + l), where hp t = the total power, and hpg = the power required for pure gas.

Jan 1, 1967

In 1991, the USBM (U. S. Bureau of Mines) evaluated the mineral resources of the 174,550-acre Bear Creek-Poker Peak area. Located 40 air miles east from Idaho Falls, ID, the study area is in the Caribou National Forest but is mostly administered by Targhee National Forest. USBM personnel mapped and sampled mines, prospects, and mineralized sites in and near the study area. Five types of mineral occurrences were identified in the study area: phosphate, limestone and travertine, placer gold, coal and uranium (the latter contained in the coal), and oil and gas. The study area has a high potential for oil and gas; evaluation of these commodities were beyond the scope of this study.

Jan 1, 1992

By M. C. Irani

This Bureau of Mines survey of methane emissions indicates that total daily emissions have declined from 227 MM ft3 in 1971 to 214.7 MM ft3 in 1973. The highest average daily emissions in million cubic feet per day observed in U.S. bituminous coal mines were, in decreasing order, Monongalia County, W. Va., 40.7; Marion County, W. Va., 23.1; Buchanan County, Va., 22.1; Washington County, Pa. , 12.4; Greene County, Pa. , 11.7; McDowell County, W. Va. , 11.4; Cambria County, Pa., 9.8; Jefferson County, Ala., 9.5; Wyoming County, W. Va., 6.0; Marshall County, W. Va., 4.8; and Indiana County, Pa., 4.8.

Jan 1, 1974

By Radford Schantz

In 1990, the Bureau of Mines (BOM) conducted a mineral investigation of the mines and prospects in the East Mojave National Scenic Area (EMNSA). San Bernardino County. California During field work. BOM identified 701 mines and prospects in EMNSA for which the geology, mineral resources, and mining history were compiled and summarized. Analytical results for 1.188 rock samples collected are tabulated. Total value of identified resources in EMNSA is $5.0 billion. Twenty-four mines and prospects were deemed profitable under current economic conditions. Development could generate considerable economic benefits to San Bernardino County. Potential economic benefits from mining the deposits were evaluated under the following access restrictions for EMNSA: 1) fun access, 2) HR 3460, and 3) S 11/HR 780. Under the full access scenario, cumulative mine revenues are $3.0 billion, cumulative personal earnings at mines and supporting industries are $0.94 billion, and annual jobs at mines and supporting industries are 2,379. Under HR 3460, mine revenues, personal earnings, and annual jobs are $2.9 billion. $0.88 billion, and 2,165, respectively. Under S 11/HR 780, mine revenues, personal earnings, and annual jobs are $1.0 billion, $0.32 billion, and 936, respectively.

Jan 1, 1990