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By R. J. SHAW

Oil shale has been defined as, "a compact, laminated rock of sedimentary origin yielding over 35 percent of ash and containing organic matter that yields oil when distilled but not appreciably when extracted with the ordinary solvents for petroleum." The oil-yielding organic matter in oil shale, commonly called kerogen, decomposes upon application of heat to form bituminous materials that are soluble in organic solvents and may be extracted from the inorganic residue. However, separation usually is accomplished by continuing the heating and thereby cracking the primary bitumens to gas and oil, which distill, leaving a carbonaceous material on the mineral residue. It has been suggested that this conversion takes place only at relatively high temperatures - 750°F or higher. On the other hand, other workers have found that transformation may take place to some extent at temperatures as low as 400°F. In either a solvent extraction or a destructive distillation process for separating organic material from the inorganic portion of oil shale, the quantity of heat required to raise the temperature of the oil shale sufficiently to induce a satisfactory rate of conversion of kerogen to oil is important in determining the design of an economical process. Likewise, the quantity of heat recoverable from a spent shale is important in determining the overall heat balance of the process. Published data on the specific heat of American oil shales are meager. Gavin and Sharp present data for two samples of Colorado oil shale, one from near DeBeque and one from Parachute Creek, and for a sample of spent shale over a temperature range of 68°F to 1940°F. McKee and Lydor present data on the specific heat of two samples of oil shale from near DeBeque, Colorado. Additional thermal data on various grades of oil shale over a wider range of temperature are needed in order to apply sound engineering practices to the design of equipment for processing oil shale.

Nov 1, 1947

By John Nagy

Results of initial research by the Bureau of Mines are given on the dust explosion hazard of float coal and on the related factors of occurrence, rate of production, sampling techniques, transport, and deposition of float coal. Tentatively, it is suggested that where float coal deposits prevail, a mini-mum of 80 percent incombustible be maintained in the top 1/8-inch layer to neutralize the explosion hazard of the surficial coal deposit.

Jan 1, 1965

By ALICE V. Petar

Like many gem materials, amber has a colorful history which may be traced through the writings of the ancients and the ornamental relics discovered from time to time. Like few gem materials, however, it is distinctly useful in products whose value has no connection with the gem industry. Long prized for its beauty, amber was fashioned into articles of jewelry and ornaments to please the fancy of ancient rulers and to find a place among treasured pos- sessions in their tombs; it has been used by adherents of various creeds for rosaries and other religious symbols; and although still sold for these pur- poses it also lends itself to such commercial purposes as raw material for varnish. Amber is only on the border-line of the mineral kingdom; actually it is of vegetable origin, having been formed as resin from trees of the conifer family that existed during the Tertiary period. It is the hardest of the fos- sil gums. The United States produces no amber, although a few occurrences are known. Most of the world's supply comes from East Prussia, where it is ob- tained from both land and sea. For many years pieces of amber were gathered from the Baltic by fishermen and deep-sea divers; and although about 10 per- cent of the Prussian amber is still recovered from the sea, most of the out- put is mined from open pits on the Samland Peninsula.

Jun 1, 1934

By R. L. Brown

This report, the seventeenth in an annual series, summarizes Bureau of Mines research and technologic work on coal and related investigations for July 1, 1951, to July 1, 1952. It 1s based largely on publications issued during the fiscal year, although 10 some instances data are presented that have not been published previously. Footnote references are given to the publications so that further details on the work may be obtained. Bureau of Mines research on the mining, preparation, and utilization of coal is directed toward developing and encouraging safer and more efficient mining practices and preparing and utilizing coals to the best advantage.

Jan 1, 1953

By V. E. Homme, M. M. Wong

Tests were made in reactors ranging from 12 to 30 inches in diameter to develop methods for the preparation of sodium chloride - titanium lower chlorides ( dichloride and trichloride ) melts that contain titanium predominantly in the divalent state . Such melts are desirable as a starting material for the production of titanium metal or as an electrolyte for electrorefining of titanium . Sodium reduction of TiCl with an 18 - hour period of holding the reaction products in the molten state produced melts that contained titanium lower chlorides in TiCl₂ - to - TiCl , molar ratio of approximately 8 to 1. Sodium reduction of TiCl in a reactor with a shielded pipe weir , that required no melt -holding period , produced melts with a TiCl₂ - toTiCl , molar ratio as low as 4 to 1 . Reduction of TiCl4 with scrap titanium metal in molten sodium chloride produced relatively pure melts containing about 27 percent titanium in a Ticl₂ - to - Ticl , molar ratio of approximately 4 to 1 .

Jan 1, 1964

By Jr. Sharkey

The Bureau of Mines investigated gases from flash and laser irradiation of Pittsburgh seam (hvab) coal to determine the action of high temperatures on coal. Temperatures in excess of l,000° C were reached with both types of irradiation. Craters about 300 microns in diameter were produced in the coal with millisecond pulses from the laser unit rated at 1.7 joules' output. Gaseous products from laser and flash irradiations in vacuum contained 21 and 8 percent acetylene, respectively. Diacetylene, vinylacetylene, and other products to molecular weight 130 were indicated in the mass spectrum of the gas from the laser study. Single experiments were also conducted in which the laser energy, particle size of the coal, and atmosphere were varied. The results indicated that the distributions of products obtained from the flash and laser irradiations of coal were different from that produced in high-temperature carbonization.

Jan 1, 1966

By David E. Fogelson

The breakage of rock by explosives depends largely on the ability of an explosive to transfer its stored potential energy to the rock as strain energy. Therefore, the relative rock-breaking abilities of explosives can be determined indirectly by determining the relative amounts of strain energy transferred to the rock at the time of detonation. This report presents experimental data on the strain energy contained in explosion-generated strain pulses in a granite gneiss. Six explosives were tested. The scaled total radial strain energy Es/W flowing outward through a spherical shell of scaled radius R/W1/3 surrounding the point of detonation was found to follow an exponential decay propagation law of the form [ ]

Jan 1, 1959

By Stephen P. Holt

In the fall of 1946 and spring of 1947 the Bureau of Mines put down five inclined diamond-drill holes totaling about 3,100 feet of bore to test for the possible eastward extension of the Royal Princess ore deposit in Jo Daviess County, Ill. Attention of the .Bureau was first directed to this property by the Illinois State Geological Survey. The history of production of the Royal. Princess mine and reports as to the size and nature of the deposit were considered justification for investigating the trend of the mineralization. This report describes the work done by the Bureau of Mines and presents the data obtained.

Jan 1, 1948

By E. J. Lintner

This paper is one of a series being prepared by the United States Bureau of Mines describing clay mining, crushing and grinding methods, and costs at various clay-mining operations throughout the United States. These papers are designed to disseminate technical information regarding methods used. The cost tabulations represent local operating expenditures only and not total production costs. Although the publication of total production costs might not be advisable in some instances, yet a knowledge of operating costs is essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called to-this distinction between total and operating costs in order that no misunderstanding of the cost tabulations shall ensue. The following report deals specifically with the methods employed by the Dennison Sewer Pipe Co., Dennison, Tuscarawas County, Ohio.

Jan 1, 1936

By E. J. Matson

From February until July 1943 the Bureau of Mines conducted an exploration project at the Majuba Hill mine to determine tonnage aria grade of the copper and tin ore and to search for extension of the mineralization. The work comprised sampling, long-hole drilling, underground excavation, and ore-dressing test.

Jan 1, 1948

By C. J. Chindgren

Two air classification systems were built and tested as separatory devices for recovering the nonferrous metal values from shredded automotive nonmagnetic reject scrap. A horizontal air system with a capacity up to 16 tons per hour was used to obtain preliminary separations, and a smaller capacity vertical system was used as a cleaning device. Shredded automobile reject material containing aluminum, copper, and zinc values of about $55 per ton were air-classified in the horizontal elutriator. Ninety-six percent of the metal was recovered in a 74-percent metal concentrate. Tandem operation of both classifiers recovered 92 percent of the metal in an 80-percent concentrate while rejecting 87 percent of the nonmetallics. Heavy media separation of the air-classified concentrate produced an overall recovery of 91 percent of the metal in the form of a 99-percent metal concentrate.

Jan 1, 1971

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 L. M. Demers, D. C. Kuhn

It has been suggested that radicals on the surface of dust particles are key chemical factors in the pathophysiology that results from the occupational inhalation of coal and silica dust. In addition, oxygenated derivatives of arachidonic acid (eicosanoidsJ have been implicated as important biochemical mediator5 of mineral dust-induced lung disease through their role in bronchial and vascular smooth muscle reactivity, inflammation, and fibrosis. Therefore, we assessed eicosanoid production by the rat alveolar macrophage (AM) exposed in vitro to mineral dusts with varying surface chemical characteristics in order to determine if radicals associated with the mineral dust could influence the production of proinflammatory mediators in the lung environment. Primary cultures of rat AM were exposed to freshly fractured or "stale" bituminous coal dust, as well as untreated silica or silica calcined to 500 and 1100°C. Prostaglandin E1 (PGE;V, thromboxane Ai (T}(Ay, and leukotriene 84 (LTB; levels in incubation medium were determined by specific radioimmunoassay. When AM were exposed to freshly fractured coal dust, PGE2 production was markedly increased. In contrast, exposure of AM to "stale" dust significantly reduced PGE1 production. Exposure of AM to freshly fractured coal dust resulted in a significant increase in production by AM, while exposure to stale coal dust did not influence AM TXA1 production. Neither "fresh" nor "stale" coal dust had any effect on LTB4 production. In vitro exposure of AM to untreated silica resulted in a significant increase in TXA1 PGE.,, TXA; and LTB4 production compared with control. However, exposure of AM to silica calcined to 11oo•c resulted in eicosanoid levels that were not significantly different from control. These effects were still apparent 8 wk after calcination of the silica particles. Silica was a more potent activator of AM eicosanoid production than was coal, and amorphous fumed silica was a more potent activator of AM eicosanoid production than was crystalline silica. These findings suggest that radicals associated with respirable coal and silica particles may play a key role in the ability of mineral dust to activate AM eicosanoid production and therefore may be important in the pathophysiological consequences of occupational mineral dust inhalation.

Mar 1, 1992

By D. C. Dahlin

The Bureau of Mines investigated the Ketchem Dome tin prospect in east-central Alaska to evaluate the tin resource. The studies included field investigations, mineralogical characterization, and concentration of the tin-bearing minerals. The tin mineralization consists of cassiterite (Sn02), which occurs as grains disseminated in a greisen (quartz-mica) matrixo A bulk sample from the largest and best-developed greisen vein exposed at Ketchem Dome contained 0.51 pct Sn. Concentration of the cassiterite by gravity table methods resulted in a product that contained 56 pct of the tin at a grade of 41.4 pct Sn. The mineralization exposed at Ketchem Dome is typical of greisen found in the area and elsewhere in interior Alaska.

Jan 1, 1987

By Bruce I. Thomas

The occurrence of tin-bearing gravels along Tozimoran Creek in central Alaska has been known for a number of years. In September 1944 the Bureau of Mines investigated an area approximately 1,000 feet long and 200 feet wide along Tozimoran Creek to deter-mine the cassiterite content of the stream gravels, which are about 4 feet deep and covered by 3 feet of overburden. Nine trenches and two shafts were excavated, from which samples of the underlying gravels were taken. This report contains a discussion of sampling methods and tables giving the results of analyses.

Jan 1, 1948

By David A. Benjamin

The USBM (U.S. Bureau of Mines) studied mines, prospects, and mineralized sites in the Roberts WSA (Wilderness Study Area) in 1984. The 15,090-acre WSA, located 35 miles northwest of Eureka, NV, is underlain by alluvial deposits of Quaternary age, extrusive and intrusive volcanic rocks of Oligocene through Miocene age, and metasedimentary rocks of Cambrian through Permian age. The Roberts Mountain Thrust fault cuts through the WSA, dividing the metasedimentary rocks into upper and lower plate rock units. One mine, the Kelley, which produced 397 tons of lead-zinc ore prior to 1940, and two prospects are within the WSA; no resources were identified. Exploration for precious metal deposits is presently being conducted in and adjacent to the WSA on large claim blocks. The study area contains six sites in and near these claim blocks that have anomalous gold and silver. Detailed exploration is needed to delineate resources. High purity silica rocks are present in the WSA. Barite, phosphate, oil shale, and vanadium occurrences just outside the WSA may extend into it, but no such occurrences were observed during the USBM study.

Jan 1, 1986

By A. J. Barry

This report presents observations made by Bureau engineers regarding hydraulic-powered roof supports that are currently being used or have been used on nearly all operating longwalls in the United States, A comparative summary of specifications for various types of powered supports with a brief description of the mine conditions has been compiled to enable mining engineers and mine operators to readily evaluate the differences in design data. Some of the support data furnished in the field may vary from those listed in manufacturers' brochures because of the trend to customize various support components to meet specific mine conditions. A method of estimating support requirements for different assumed operating conditions is presented. Similar computations for specific mine conditions may be used to make preliminary estimates of support requirements.

Jan 1, 1969

By A. E. Back

A method has been developed in the laboratory for successfully treating titaniferous magnetite ore from the deposit at Iron Mountain, Wyo. The ore is roasted with 15 percent sodium carbonate to convert the vanadium to a water-soluble form and fix the soda for the subsequent electric-smelting step. Approximately 90 percent of the vanadium is recoverable in a product assaying 80 percent V2O5. The leached calcine is briquetted and smelted in a graphite-lined electric-arc furnace. Substantially all of the titanium is recovered in a soda slag, assaying 60 percent TiO2 and 2 percent Fe, which can be upgraded to 75 to 80 percent TiO2 by leaching with dilute sulfuric acid. The upgraded slag could be utilized for the production of titanium dioxide pigments or titanium tetrachloride. About 90 percent of the iron is recovered as pig iron, containing only minor amounts of vanadium, titanium, and sulfur. The high TiO2 slag compares favorably with slag containing about 70 percent TiO2 being produced by the Quebec Iron & Titanium Corp. at Sorel, Quebec. The data obtained from this investigation indicate that a feasible process has been developed for treating Iron Mountain ore, and larger-scale testing is warranted to develop engineering data for the ultimate utilization of this deposit as a source of titanium, iron, and vanadium. There are adequate supplies of basic raw materials, electric power, water, sodium carbonate, coal, and petroleum products within fairly short distances of Cheyenne and Laramie, Wyo., the nearest cities and probable plant- and labor-supply points.

Jan 1, 1952

By T. E. Swigart

In connection with experimental work by the Bureau of Mines to determine effects of back pressure . on oil wells * , data were compiled on the engineering conditions in the oil field selected , in order to afford a more complete understanding of the wells tested , and to illustrate the extent to which underground conditions should be studied when making oil -field experiments of this nature . This report , containing the data mentioned, may be of interest to the oil industry , as it describes briefly the methods of operation employed in developing and exploiting shallow well territory .

Feb 1, 1923

By Oliver C. Ralston

The growing popularity of perlite (sometimes spelled pearlite) as a raw material for thermal expansion into pumicelike products in the Western States has prompted a preliminary investigation of the properties of such material and the problems that want solution to put a perlite industry on a firm foundation. The Bureau of Mines is undertaking the gathering of data and the solution of these problems, and the following paper records some of the available information. and the promise of the material, with some comparisons of advantages of the various competing lightweight aggregates that can be made from siliceous volcanic glasses and rocks containing entrapped or dissolved water that causes their expansion on' quick heating to their softening points. This new industrial rock has caught the fancy of the mineral industry in the western States because it has Fume advantages over natural pumice. Chemically, it is typified as rhyolitic in composition, and one may find obsidian, rhyolite, pumice, pumicite, and perlite from the same vant and contemporaneous in origin. The material need not be rhyolite but should be a siliceous or acid lava and contain 2 to 5 percent water still in "solution" in the rock. On quick heating to the softening temperature the material puffs, due to conversion of the contained eater into bubbles of steam. Slow heating causes gradual release of the imprisoned water by decrepitation and. cracking and-results in, very little puffing. Perlite is often in the form of ovoid volcanic bombs formed by explosive eruption of large masses of lava into the air, where they, quickly cool, with escape of little of the contained water, exceptt perhaps for a hollow interior. Since they cool in layers they have an onion-type structure and a pearly luster from interference of light between the. layers, which is' the origin of the name "perlite." Perlite may occur in intruded flows that have been quickly cooled and partly expanded but retained most of their magmatic water content. Obsidian may be the same lava cooled quickly under conditions that prevented crystallization of feldspars and other minerals, leaving the volcanic glass that may or may not retain all of the original contained water.

Jan 1, 1946