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By Deborah A. Kramer

As part of the Nation's growing concern with the competitiveness of U.S. firms in the world economy, especially with respect to advanced materials, the Bureau of Mines assessed the actual and potential recovery and manufacturing capabilities for gallium and gallium arsenide (Gacis). GaAs has advanced from a laboratory curiosity to a material with important "high-tech applications within only the last few years, and although protected North American gallium supplies are currently considered adequate, consumption could grow to the point that this assessment would need reevaluation.

Jan 1, 1988

By H. E. Sanford

"INTRODUCTION Of the occupations in and about coal mines, those of the haulage crews are among the most hazardous. Statistics indicate that the second largest number of fatalities about coal mines occurs during haulage operations and through the use or misuse of haulage equipment. Despite the fact that relatively few coal-mine employees are engaged continuously at haulage operations, approximately 20 percent of all coal-mine fatalities are attributable to haulage.Most of the hazards in haulage operations could be very greatly reduced if more serious consideration were given to the problems of the haulage crews and if sincere efforts were made to reduce the hazards. Underground haulage is similar in many respects to railroading; yet, railroading is now considered one of the safest of occupations a distinction that has been attained only by honest effort and whole-hearted cooperation on the part of all concerned. Underground haulage is also similar to street and highway operation and has in it some of the difficulties encountered in the reduction of traffic accidents the seriousness of which has not by any means been con¬trolled as yet, notwithstanding the fact that much effort has been expended through a multiplicity of laws, ordinance regulation, etc., as well as by thousands of enforcement agencies and officers.The men working on the locomotives are among the most important members of a coal-mine organization; without skilled haulage employees, the production of coal would be greatly retarded. Their jobs, particularly the job as brakeman, require physical endurance, agility, and mental and physical alertness; in thin coal beds, especially where the roof is not brushed and the coal is loaded into mine cars by hand, the need for these qualifications is greatly increased."

May 1, 1948

By A. W. Deurbrouck

This report presents the results of a washability study of 322 coal mine samples showing the sulfur forms and distribution in the coals. The samples were collected from mines which were principally utility coal producers. Generally, the data show the total sulfur content of the coals evaluated could be significantly reduced by some combination of stage crushing and specific gravity separation. However, few coals could be upgraded to a final product containing 1 percent or less total sulfur. The complete washability data are presented for each sample processed. A statistical evaluation is included for the coalbeds from which more than 10 samples were collected and for the geographical coal producing regions. A graphical summation is presented for the coal producing regions and selected coalbeds.

Jan 1, 1972

By D. E. Shanks

The Bureau of Mines investigated the effects of HCI concentration and solution temperature on the solubility and crystal form of the chlorides of Co, Mn, and Ni when sparged with HCI gas at temperatures of 20°, 40°, and 60° C. Increasing HCI concentration in solution caused the chlo-rides of Co, Mn, and Ni to crystallize (salt out) because of the common ion effect. The salting-out crystallization was most effective for NiCI2, which had a solubility of 0.7 pct at 20° C and maximum HCI concentration. COCl2 salted out to a minimum solubility of 9.4 pct at 20° C and 22 pct HCI concentration and increased in solubility at greater HCI concentrations because of the formation of chloride complexes. MnCl2 was intermediate in behavior. The effect of temperature on solubility was greatest for CoCl2 and least for NiCI2, 15 and 7 pct change, respectively, over the temperature range of 20° to 60° C. The salted-out chlorides of cobalt and nickel formed the hexahydrates and those of manganese formed the tetrahydrate in saturated metal chlo-ride solutions at 20° C and low concentrations of HCI. Increasing the temperature or the HCI concentration caused a 108s in waters of hydra-tion. At 60° C, the salted-out crystals of NiCl2 formed the tetrahydrate in HCI concentrations up to 18 pct and the dihydrate at higher concentrations, while cobalt and manganese chlorides formed the dihydrates, even in water.

Jan 1, 1985

By T. W. Goodman, J. Cervik

The Bureau of Mines conducted studies to compare the effectiveness of the cross-measure borehole system with that of surface gob holes on two successively mined retreating longwalls in the Lower Kittanning Coalbed. Only the cross-measure system was in operation on panel A; on panel B, both systems were in operation. In addition, the cross-measure bore-holes on panel B were drilled parallel to the face, whereas those on panel A were drilled at a 45O angle with respect to the longwall axis. The studies show that the cross-measure system captured 71 pct of the methane generated by longwall mining on panel A. On panel B, the sur- face gob hole dominated over the cross-measure system for about 700 ft (213 m) after it was intercepted. Beyond that point, the cross-measure system dominated. About 93 pct of the methane generated on panel B was captured by the two systems. Cross-measure boreholes that were drilled parallel to the face were as effective as boreholes oriented 45" with respect to the longwall axis. In addition, they are shorter and require less drilling time. Comparison between observed gas pressure differentials in boreholes and calculated values indicate that boreholes can be shortened further to 140 ft (43 m). Additional studies are needed to verify these calculations.

Jan 1, 1986

By R. L. Montgomery

The heats of solution of erbium chloride in water and in hydrochloric acid and of erbium oxide in hydrochloric acid were determined. The results reveal a discrepancy of 10.5 kcal. per gram-atom between the heats of combustion and solution of erbium reported in the literature, the heat of combustion being more negative. The heat of combustion of erbium t4)4 and its heat of solution in hydrochloric acid (1, 18) have been reported in the literature. The heat of solution of erbium chloride was determined in two studies (2, 19). The present work was undertaken to check the reported heats of solution of erbium chloride and to determine the heat of solution of erbium oxide in hydrochloric acid. The latter quantity permits the heats of combustion and solution of erbium to be compared for mutual consistency. It was also desired to determine the degree of similarity between the thermochemistry of yttrium and erbium.

Jan 1, 1961

By R. D. Leitch

"INTRODUCTION This report is another of the series on the effect of drouth and low water on the pollution of streams by coalmine drainage. A previous report3 dealt with work on Bennett Branch of Sinnanahoning Creek, Pa. This report deals with the results obtained during a similar study of Black Lick Creek, Two Lick Creek, and Yellow Creek. All of these belong to the same drainage system. Two Lick Creek is a tributary to Black Lick Creek, and in turn Yellow Creek is a tributary to Two Lick Creek, as shown in Figure 1.Black Lick Creek was of such a volume that a seasonal investigation was not entirely feasible. Yellow Creek was found to have mines only near the mouth, except a few of status unknown to the writer at the extreme head-waters, and the stream was also more or less inaccessible for regular and frequent sampling. Two Lick Creek was found to be most suitable of the three.ACKNOWLEDGMENTThe work reported has been carried on under the direction and with the advice of Dr. R. R. Sayers, chief, health and safety branch, and W. P. Yant, supervising engineer, Pittsburgh Experiment Station."

Jul 1, 1931

By John J. Mulligan

Ear Mountain is an isolated mountain mass that rises abruptly from the coastal plain on the northwest shore of the Seward Peninsula. Geologically it resembles the more accessible Brooks Mountain and Cape Mountain areas to the southwest, being composed of a granitic core surrounded and partly capped by metamorphosed sediments. The occurrence of lode- and placer-tin deposits in this area has been known since the early 1900's, when the Seward Peninsula region was prospected extensively for both gold and tin. The Federal Bureau of Mines investigated the tin deposits in the Ear Mountain area during the 1953 and 1954 field seasons. The objectives were to delimit the areas in which tin minerals occur, as a guide to future prospecting, and to determine the amount of tin in the known prospects. Work by the Bureau of Mines included both placer and lode sampling.

Jan 1, 1959

By George S. Rice, J. W. Paull, R. R. Sayers

"Standard rock dust for use in the rock dusting of coal mines might be defined tentatively as powdered mineral, light colored and free of carbonaceous matter and free silica, all of which will pass a 20-mesh screen while 50% of it will pass-through a 200-mesh screen.Such dust may be prepared from limestone, gypsum, anhydrite, or shale free of sand and flint. For the initial rock dusting of the average nongaseous bituminous mines enough standard rock dust should be applied so that the combustible content of the resulting mixture of rook dust with mine dust shall not exceed 45%, a range somewhere between 35% end 45% being the practical objective sought.All entries, slopes or passageways and room necks should be rock dusted.Additional safeguards are:a.,Rockdusting roomsb.,Scattering of dust in vicinity of shots before firing.c.,Placing of barriers in the mouths of panels, cross-entries and other key positions.Redusting becomes necessary whenever the combustible content of the mine dust exceeds the permissible maximum. This should be determined by regular, systematic sampling, followed by a simple analysis of the samples for combustible content. A Bureau of Mines volumeter for measuring the density can be used for the determination of combustible content."

May 1, 1924

Control dust generated during undercutting in salt mines without causing ore-solubility problems that result from excessive water use. Approach A foam generator was developed to provide a reliable foam to control dust on cutting machines used in mining water-soluble ores. The system was designed to keep total foaming agent/water mixture flowrates below the flow-rates characteristic of water-only systems. The foam generator consists of a reservoir to hold the premixed agent and water, a metering pump, and a small compressor to aerate the mixture. The system is compatible with all cutting machines. How It Works One of the current wet-bar techniques, the through-the-bar trickle system, pumps water through a pipe in the cut-ting bar to its tip placing the water behind the kerf. If the pipe conducted foam effectively the foam would be released in the kerf where it would mix with the cuttings and the dust produced by the chain. For improved foam delivery, however, it is recommended that the pipe be replaced with an external channel welded along the top of the bar. This provides excellent dust control while avoiding the accumulation of copious quantities of foam in the heading. The system is very simple. The foam generator is a 50-gallon tank filled with a mixture of water and foaming agent. The mixture is pumped through a wye fitting to a second line where it is mixed with compressed air, (300

Jan 1, 1984

By A. J. Kraemer

The Bureau of Mines for a number of years has been carrying on an investigation of properties of crude petroleum from producing, fields in the United States and the Western Hemisphere, and has published a series of reports on these fields, including oil fields of Oklahoma2. Acknowledgements Thanks are due to R. R. Brandenthaler and Peter Grandone, of the Petroleum Experiment Station of the Bureau of Mines, at Bartlesville, Oklahoma, who reviewed the manuscript and contributed valuable suggestions. The samples were analyzed under the direction of E. C. Lane at the Bartlesville station of the Bureau of Mines.

Jan 1, 1927

By C. H. Elder, M. C. Irani

Two degasification test boreholes were drilled to depths of 1,238 and 1,212 feet on Bureau of Mines property at Bruceton, Pa., as part of the Bureau's long-range coal degasification program. The holes provided detailed geologic information and geologic sections, which were correlated with regional stratigraphic cross sections prepared by the Pennsylvania Geological Survey. Gas content determinations and coal analyses were made on the Upper Freeport, Middle Kittanning, Clarion, Brookville, and Mercer coalbeds; gas content of the coalbeds ranged from 53 to 165 cubic feet per ton. Formation pressure and gas flow tests were conducted on selected coalbed intervals in borehole 1; formation pressures ranged from 292 to 473 psig. The middle Kittanning coalbed was hydraulically stimulated using very heavy gelled water, but gas production remained low because gel residue and formation water inhibited the flow of gas. Gas contents in the Clarion, Upper Brookville, and Mercer coalbeds were anomalously low owing to the proximity of porous sand- stones which act as reservoirs for gas migrating from coalbeds.

Jan 1, 1977

By W. A. Calhoun

A method for concentration of the nickel-cobalt-bearing mineral, siegenite, from a table middling has been developed by the Bureau of Mines at Rolla, Mo. The table middling is composed of a complex series of sulfide minerals, occurring in mill operations in the southeast Missouri "lead belt." In these operations the siegenite is lost as a separate concentrate, being diverted to other products. The procedure also includes recovering commercial-grade concentrates of copper and lead. A low-grade zinc concentrate, a potential coproduct, was also made.

Jan 1, 1962

By David R. Hanson

Transient electrical noise events pose serious problems for data acquisition systems used in monitoring acoustic emissions in laboratory and field environments. The U.S. Bureau of Mines has designed and constructed a trigger discriminator circuit for use in ultrasonic acoustic emission studies. Designed for use with signals in the frequency range of 50 to 400 kHz, the instrument examines .incoming signals for frequency content, amplitude, simultaneity, threshold crossings, and number of channels above threshold. If preselected criteria on these properties are met, a plus 5-V pulse is output that may be used to trigger a data acquisition system, allowing rejection of noise events that do not possess useful information. The system was designed for four input channels, but may be expanded to more channels with minimal design changes.

Jan 1, 1995

By R. L. Stein

For the past several years, the Bureau of Mines has been actively engaged in developing two new oxygen self-rescuers through research contracts with private industry. These new oxygen self-rescuers are designed to be carried by a miner while he is at work and are used during emergency escape, supplying high-purity oxygen to the user and, at the same time, absorbing carbon dioxide (C02), The first of the two new self-rescue breathing devices is a 10-minute, self-contained apparatus developed by the Mine Safety Appliance Co, Size and weight of the unit are comparable to the currently used self-rescue devices. The second device, designed and developed by Lockheed Missiles and Space Corp., is 8. 4.5-lb package which supplies 1 hour of oxygen to the miner. Both devices have a canister which contains the oxygen-producing and CO2-absorbing potassium superoxide chemical, a breathing bag, a bite-type mouthpiece, noseclip, goggles, and hoses connecting the canister and mouthpiece. When needed in an emergency, the miner removes the outer protective cover and dons the unit. For both devices oxygen is immediately available once the mouthpiece is placed in the mouth. These two new units have received prototype approval from the National Institute for Occupation and Safety Health (NIOSH) and the Mining Enforcement and Safety Administration (MESA).

Jan 1, 1976

By Robert J. Willard

This chapter includes tables for 1982 that were not available in time for publication of the 1982 Minerals Yearbook, but does not include corresponding tables for 1983. The value of raw nonfuel minerals produced in the United States during 1988 was estimated at $21.1 billion, an increase of $1.5 billion over the value for 1982. This is a reversal of last year's downturn in value from that of 1981, which was the only decrease noted since 1971; hence, an overall trend of increasing values has been maintained for 12 years, except for 1982. Although the reversal is a basis for cautious economic optimism, it is tempered by continued problems in the domestic mining industry: inadequate funds for capital investment and competition with other countries that have lower production costs. Output of metal commodities in 1983 increased for 8 out of 21 metals, and metal values, in general, increased for 9 of the metals. Output of nonmetal commodities was mixed, with 24 nonmetals showing increases, 20 showing decreases, and 2 unchanged. Nonmetal values were also mixed in 1982: 25 showed increases, 20 declined, and 1 was unchanged. Improvements in the international metals market have not been forthcoming because of the continued depressed prices for major metals. Governments in foreign producing countries have been concerned with maintaining employment and continuing foreign exchange flows through mineral exports. Consequently, the excess of supply in the face of shrinking demand brought downward pressure on metal prices in general, except for the precious metals. On the domestic front, this situation means U.S. mining companies must become even more cost efficient. The major trend in the mining industry in 1983 was to cut costs further, reduce or stabilize total production, reduce outlays for major capital equipment, modify existing systems and equipment, and streamline operations. Most of the accomplishments reported herein reflect this trend.

Jan 1, 1984

By Robert Blickensderfer

Equipment and procedure for the continuous roll bonding of metal strips are described. The reels, mill rolls, and furnace were located within a vacuum chamber capable of operation at a residual gas pressure of 1 x 10-4 to 1 x 10-5 torr. Several metals were successfully clad at rolling temperatures of 930° to 1,050° C in lengths up to 120 ft. The bimetals that were clad included stainless steel to carbon steel, molybdenum and nickel to stainless steel and carbon steel, and titanium to carbon steel. Bend tests of bond integrity are described, and microstructures of the interfaces are presented. The amounts of brittle intermetallic phases formed at the interface are minimized by this cladding method.

Jan 1, 1980

By P. Bhakta

The U.S. Bureau of Mines developed an alkaline oxidative pretreatment leaching procedure to increase the recovery of gold from arsenopyrite (FeAsS) ores. The best solution compositions for arsenopyrite dissolution were determined using cyclic voltammetry and chronocoulometry. Initial arsenopyrite dissolution occurred at -0.20 V versus standard hydrogen electrode (SHE) in a sodium hydroxide (Na0H) solution. Leaching of a high-grade arsenopyritic ore containing, in percent, 28.2 As, 25.3 Fe, 19.9 total S, and 1.0 Sb and, in troy ounces per short ton, 1.6 Au and 5.5 Ag resulted in >90 pct As extraction at 1000 C, 40 psig O2,4 h, and 2M NaOH solution in a 2-L autoclave. Cyanidation of the leach residues resulted in 90 to 93 pct Au and 60 to 80 pct Ag extractions, compared with only 5 and 15 pct, respectively, without the pretreatment. The procedure was further tested by leaching a low-grade gold ore and a bulk sulfide flotation concentrate prepared from it. Cyanidation of the leach residues resulted in 70 pct Au and 31 pct Ag extraction. The NaOH leachate was partially regenerated by precipitating the arsenate as calcium arsenate [Ca3As04)2] and the sulfate as barium sulfate (BaS04).

Jan 1, 1989

By A. L. Engel

Many western ores containing ;old, silver, and copper can be mined and concentrated at a profit only when the recovery of those metals is high and treatment costs are low. Usually, ores containing easily dissolved copper minerals, or copper minerals that become soluble to some extent through oxidation during treatment, present a real problem in cyanidation. Copper cyanide compounds are formed that tend to 'precipitate and that cannot yield regenerated cyanide and metallic copper on contact with zinc. This results not only in some loss of copper through solution in cyanide, but in excessive consumption of cyanide above the amount required for the extraction of Gold and silver. Any moans, therefore, of minimizing the: loss of cyanide while at the same time effecting high recoveries of the several values contained in the ore is of wide interest. A sample of typical low-grade ore of gold, silver, and copper, containing copper-sulfide minerals, was obtained from the MacLaren Gold Mines Co., Cooke, Park County, Mont., for laboratory investigation by flotation and cyanidation.

Jan 1, 1950

To reuse chromium, nickel, and molybdenum now lost in stainless and specialty steel-making wastes, and simultaneously to overcome the current environmental problem resulting from landfilling these wastes. Approach A variety of stainless and specialty steelmaking wastes are agglomerated and recharged into the plant's electric arc furnaces. How It Works Stainless and specialty steel-making wastes such as bag-house dust from the electric arc furnace, dust from the argon-oxygen decarburization unit, grinding swart, and mill scale are blended in proportion to the ratio in which they are generated. Next they are agglomerated on a pelletizer with an addition of a small amount of carbonaceous reducing agent, and air-dried in preparation for being recharged into the furnace. Some mixtures of wastes tested in the laboratory required the addition of binders and/or the use of ovens in lieu of air-drying to produce sufficient pellet strength. Although the optimal maximum particle size of wastes being pelletized is 35 mesh, somewhat larger particle sizes were satisfactorily pelletized during in-plant tests. The photograph shows a typical mixture of wastes and the pellets made from them.

Jan 1, 1981