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By Will H. Coghill

Recent work on beneficiation of the .Alabama red iron ores and ferruginous sandstones has brought out interesting new facts on particle-size reduction that axe a valuable supplement to what is already known.4/ The work was done by the Southern Experiment Station of the Bureau of Mines in cooperation with the University of Alabama, University, Ala., on two samples from the Birmingham district. One was an oolitic red iron ore containing about 35 percent iron; the other was a ferruginous sandstone containing about 25 percent iron, particularly attractive because of its low phosphorus content. In both samples rounded quartz (sand) grains were embedded in an oolitie, "onion skin" matrix of hematite. The hematite carries varying amounts of clay,-which limits the grade of concentrate that can be made. The clayey hematite is soft, so that the rock crumbles readily under pressure. The sand grains shell out like corn,, and without much exaggeration the mill used for differential grinding might be called a "sheller,"

Jan 1, 1940

By R. R. McLellan

The Brown Derby pegmatites are in Gunnison County, Colo., about 18 miles east of Gunnison. Approximately 860 tons of lepidolite concentrates, with smaller amounts of microlite and beryl, was produced from 3 dikes of the Brown Derby group from 1943 through 1947. No mining was done from 1948 until December 1950, when production of lepidolite and beryl was resumed by the Poston Mining & Milling Co. Mining was intermittent during 1951 and 1952. The dikes were mapped and studied by the Federal Geological Survey during the field seasons of 1942 to 1944, and in May 1950 the Bureau of Mines initiated a diamond-drilling project to test the three dikes for lepidolite and beryl. After being recessed twice, the project was terminated indefinitely July 1951. Seven drill holes were completed for a total of 1,841.6 feet of drilling.

Jan 1, 1956

By K. K. Kelley

The collection and correlation of thermodynamic data concerning substances of metallurgical interest have constituted one of the major activities of the Pacific Experiment Station of the Bureau of Mines, at Berkeley, Calif., for the past several years. Earlier bulletins (32, 33, 34, 36, 36, 37, 38) s in this series are entitled: (1) Contributions to the Data on Theoretical Metallurgy. I. The Entropies of Inorganic Substances; (2) Contributions to the Data on Theoretical Metallurgy. II. High-Temperature Specific-Heat Equations for Inorganic Substances; (3) Contributions to the Data on Theoretical Metallurgy. III. The Free Energies of Vaporization and Vapor Pressures of In¬ organic Substances; (4) Contributions to the Data on Theoretical Metallurgy. IV. Metal Carbonates--Correlations and Applications of Thermodynamic Properties; (5) Contributions to the Data on Theoretical Metallurgy. V. Heats of Fusion of Inorganic Substances; (6) Contributions to the Data on Theoretical Metallurgy. VI. A Revision of the Entropies of Inorganic Substances-1935; and (7) Contributions to the Data on Theoretical Metallurgy. VII. The Thermodynamic Properties of Sulphur and its Inorganic Compounds. The present paper collects and discusses thermodynamic data relating to metal carbides and nitrides, with the view of obtaining usable heat and free energy of formation relationships. Pertinent data on both classes of substances are difficult to obtain experimentally and consequently are extremely rare; it is therefore necessary in many cases, if equations are to be derived, to introduce certain approximations and assumptions. Lack of adequate means of checking results by utilizing data of different types, such as was done frequently in the bulletins dealing with carbonates and sulphates, are readily apparent to anyone who has made even a cursory examination of the available information. Consequently, some of the relationships derived undoubtedly will be found to be inaccurate when more or better data become available. Nevertheless, in view of the importance of some of these substances, it appears worth while to consider the information available at present and to attempt the formulation of as complete a

Jan 1, 1937

By E. D. Gardner, Edmund Stein

"IntroductionMassive sulphides occurring in metal mines are inflammable and furnish the fuel for many mine fires. Actual sampling has shown that dangerous amounts of sulphur dioxide and hydrogen sulphide may occur in mine atmospheres after blasting in massive sulphides. Probably some .of the finer sulphide in the material being blasted burns while it is in contact with the flame from the explosion. It’s also possible that oxygen of the explosive enters into the reaction.That sulphide dusts are explosive under some conditions has long been suspected, but the theory has not been generally accepted as having been proved. Evidence now at hand appears to be conclusive that such explosions do occasionally occur in mine workings in massive sulphides. Information from several mines working in heavy sulphides shows that occasionally, sulphur dioxide in larger amounts than could be expected from the blasting alone are occasionally thrown out into the mine atmosphere during blasting. Accidents have occurred and lives have been lost by men being caught in such gases. Also it appears in a few cases that damage done to timber in stopes by concussions has been greater than could 112.ve been expected from the regular blasts. In most of these cases the unusually large amounts of Sulphur dioxide could only be accounted for by an explosion or by an ignition of sulphide dusts. When this occurs it is probable that the settled dust is stirred up by the first shot of a round, then the dust cloud is ignited by this or a succeeding shot.In one instance, the senior author, while wearing breathing apparatus, returned to a station to take a gas sample immediately after a raise round had been blasted, and encountered a heavy white fume or smoke that was corrosive to the skin and which forced a retreat. The sample, which was taken farther back in a greatly diluted atmosphere, showed a high percentage (0.18) of sulphur dioxide. The station and the raise which was just being started were very dry and the walls and floor of the station contained settled sulphide dust which apparently was ignited by the blast."

Mar 1, 1928

This report summarizes the work performed under USBM Contract No. H0395041. The primary objective of this work was to extend the noise control technology developed under earlier USBM projects to a wider range of load-haul-dump models to evaluate the general applicability of these techniques. Noise control treatments were designed, fabricated, and installed on three Wagner LHDs (an 5T-2B, ST-2D, and an 5T-8A) selected as demonstration machines for this project. The machines were evaluated either in production mines or at the Bureau's Lake Lynn Mine. The results indicate that it is possible to achieve overall noise reductions of between 4 and 8 dB using these techniques. Engine cooling and seal design were determined to be important design issues in such treatments.

Jan 1, 1984

By W. W. Simpson

During cyanidation of mercury-bearing gold-silver ores, significant amounts of mercury are extracted. The presence of mercury decreases. gold loading and increases mercury stripping time on activated carbon, complicates fire refining of the gold cathodes, and creates a potential health hazard. Addition of calcium sulfide (CaS) to the cyanide leach slurry precipitates the solubilized mercury but also some silver. The Bureau of Mines investigated silver loss during CaS precipitation of mercury. Addition of 0.1 lb CaS per short ton ore to a mercury-bearing gold-silver ore precipitated both mercury and silver. However, if copper was added with CaS, or if the ore contained copper, much of the sil-ver loss was prevented. Addition of 235 ppm Cu with 0.1 lb/st CaS, prior to carbon-in-pulp adsorption, resulted in 89-to 97-pct, 80-to 91-pct, and O-pct adsorption of the solubilized gold, silver, and mer-cury, respectively, on the activated carbon.

Jan 1, 1986

By Charles F. Weber

Premature blasts of charges of explosives have caused many deaths in anthracite mines, and the causes of many of the blasts were not determined satisfactorily. Investigators often found fairly high potential differences between such metallic objects as rails, pipes, conveyor lines, or sheet-iron chutes in the working place where an accident had occurred. At one mine where a premature blast occurred in a rock tunnel, one workman was killed and two others were injured, and several days later a potential difference large enough to explode an electric squib was detected between the compressed-air pipe and the track rail; the voltage fluctuated and appeared to change with the movement of a locomotive. At another mine, a. workman was killed when a primed cartridge that he was about to load in a blast hole exploded in his hand. During the investigation, a potential difference was found between the conveyor line and the sheet-iron chute. During a 5-year Period, 61 fatalities and 771 nonfatal injuries were caused by explosives accidents in anthracite mines, and one of the chief causes of these accidents was premature blasts.

Jan 1, 1950

By H. Kenworthy

The objective of this research was to develop methods and determine conditions under which metallic sulfides with lower boiling points than sphalerite may be removed from zinc sulfide concentrates by volatilization. A higher percentage of extraction of lead, cadmium, and germanium than is common in current practice was sought. The investigation, conducted by the Metallurgical Branch of the Minerals Technology Division, Region VI, showed that, under proper conditions, it is possible to remove over 90 percent of the lead, cadmium and germanium as an enriched sublimate. The uses of lead, and cadmium to a lesser extent, are well-known. Although germanium was discovered in 1886 by C. Winkler, commercial use has been achieved only in recent years. The amount consumed per manufacturer unit is so small that the price of germanium may still be quoted by the gram. The electronic industries have been the chief consumer of this semiconductor. Germanium is sold largely to the fabricator as a dioxide for reduction to metal and subsequent processing into wafers for use in diode and triode electronic tubes. Extensive research at Purdue University during World War II led to the first practical use of germanium.

Jan 1, 1952

By Sidney Katell

This Bureau of Mines study estimates typical capital investments, operating costs, and selling prices for two bituminous coal strip mines in the Eastern and Interior provinces and a subbituminous coal operation in the Northern Great Plains province. The annual productions were based on tonnage required to fuel a 250-MM-scfd, high-Btu gas plant. The annual tonnage for the Eastern province mine is 4.8 million tons; for the Interior province mine, 6.72 mi 11 ion tons; and for the Northern Great Plains province mine, 9.2 million tons. It is assumed that the mines have a 20-year life. Wages and union welfare payments are considered as of May 12, 1974, under the terms of the Bituminous Wage Agreement of 1971, and costs for material and equipment are based on 1973 and early 1974 indexes . Initial capital investment varies: $45,358,600 for the 4.8-million- ton-per-year (MM tpy) mine in the Eastern province, $54,603,000 for the 6.72 MM tpy mine in the Interior province, and $29,871,000 for the 9.2 MM tpy mine in the Northern Great Plains province. Total capital invest-ments for the Eastern province mine, the Interior province mine, and the Northern Great Plains province mine are $61,070,000, $76,753,000, and $56,286,000, respectively. Corresponding selling prices for the coal, per ton, are $4.79, $4.23, and $2.66, assuming a 12-percent discounted cash flow rate of return after Federal income taxes. These studies are considered typical for the areas involved. Costs will vary depending on specific locations in these areas.

Jan 1, 1974

By R. V. Ramani, S. Shankar

"Available literature on the effect of re-entrainment on overall airborne dust concentration in mine airways or the fundamental mechanisms of coal dust re-entrainment in mine atmosphere is scant (Shankar and Ramani, 1991 ). Therefore, as part of the Respirable Dust Center's ongoing research, the following three-part study was undertaken:• a study of the re-entrainment phenomena of anthracite and bituminous coal dust particles in a wind tunnel under the influence of varying air velocities;• a study of the same in the Lake Lynn Laboratory Mine of the USBM with both air flow and walking by personnel causing re-entrainment; and• the mathematical modeling and computer simulation of the re-entrainment phenomenon.In this paper, results from the re-entrainment studies in the wind tunnel and the Lake Lynn Laboratory mine are presented. Comparing the results from the two studies,it was observed that increasing the air velocity increased the rate of re-entrainment ( Shankar and Ramani, I 994a) and the rate of re-entrainment decreased with the time of exposure of the source dust to the flowing air. In addition, when the source dust was composed of particles of different sizes, the airborne dust concentrations due to re-entrainment were higher than when the source dust was composed of particles of the same size. The contribution of airborne dust concentration due to air flow was negligible compared to the contribution due to walking. IntroductionIn underground coal mines, dust is produced primarily during the process of mining and during such activities as pillar spall, loading, belt transfer and roof fall. The generated dust is entrained and then collects on surfaces through dispersion, diffusion and eventual deposition. Removal forces, such as flowing ventilation air or turbulence caused by walking and moving vehicles, can re-entrain the deposited dust (Hall, 1955). A portion of the re-entrained dust remains airborne and increases the concentration of airborne dust in mine airways.The presence of airborne coal dust in mine airways in large concentrations can be hazardous. Health effects include coal workers' pneumoconiosis (CWP) and silicosis, and it can be a nuisance affecting visibility. In addition, as is common during methane explosions, if the concentration of airborne coal dust becomes significant, there could be a coal-dust explosion (Singer, Cook and Grumer, 1972; Singer, Harris and Grumer, 1974; Edwards and Ford, 1988). Through concerned research efforts over the last decade, significantprogress has been made in reducing the airborne dust concentration in mine atmospheres. However, secondary sources, such as re-entrainment, have not been studied in-depth. It is important to understand the phenomenon of re-entrainment and its potential contribution to the airborne dust concentration in mine airways for further decreasing airborne dust hazards in mines."

Dec 1, 1996

By Thomas P. Mucho, Dennis Dolinar, Christopher Mark

During the 1990s, the former U.S. Bureau of Mines conducted a number of field studies in which the performance of different types of roof bolts were evaluated in different geologic environments. The studies used a standard suite of measurements, including multipoint extensometers, strain-gauged roof bolts, and roof bolt load cells. The sites were chosen to investigate the effect of a variety of parameters, including installed tension, bolt capacity, grout annulus, and horizontal stress orientation. Although not fully successful, the measurements provided valuable insights into each of these issues. They also showed that instrumentation and monitoring have important advantages over observational methods for comparing the performance of different roof bolting systems.

Jan 10, 2000

By John C. Machisak

INJURY experience and employment data for the nonmetal mining industry in the United States are presented for the calendar year 1958. Statistical tables 6 to 12 give detailed information on injuries and employment at nonmetal mines. Data for nonmetal mines are presented separately from those for nonmetal mills, tables 23 29. The Bureau is authorized to send questionnaires to the nonmetal industry for their voluntary submission on of injury and employment experience at their operations. As this information contributes to the promotion of safety in the nonmetal mining industry, every effort has been made to make these questionnaires as complete as possible.

Jan 1, 1962

By McHenry Mosier

This paper describes the practice in diamond drilling blast holes and discusses the relative merits of this method as compared with drilling by percussion rock-drills at eastern magnetite mine A. The rooke that were drilled included: (1) Gneiss; (2) sohist; (3) crystalline limestone; and (4) granular masses of magnetite. The principal stoping methods were: (1) Sublevel open stoping and (2) inclined room-and-pillar. Diamond drilling was used in the sublevel stopes and in some of the large pillars in an old section of the mine. Experimental work on diamond drilling blast holes began in 1943. Drill- ing proved difficult owing to the occurrence of fingers of extremely hard barren rock in the magnetite ore. All diamond drilling was contracted to a firm that furnished everything necessary for drilling except compressed air and water. In most instances the diamond-drill machine is clamped directly to a 3.5-inch column to reduce vibration. For drilling in floor pillars in open stopes, the drill was set on a demountable, sectionalized steel, frame with four legs carrying a 20-foot, 3.5-inch, extra-heavy pipe. "Both coring and noncoring bits were tried. In holes drilled with a cor- ing bit, the core was ground into sludge as the bit advanced so that it was unnecessary to delay drilling for pulling core. Data on tests with several types of bits are given as well as some oper- ating results. A direct comparison of costs between diamond drilling and percussion drilling was not available. The advantages of diamond drilling blast holes at mine A included: (1) Safer working conditions in open stopes. (2) The recovery of additional ore. (3) A reduction in the amount of stops development.

Dec 1, 1946

By Albert E. Long

During the summer and fall of 1948 the Bureau of Mines, in cooperation with the U. S. Geological Survey, conducted 6xperiments in diamond core drilling in the Phosphoria formation in southeastern Idaho and southwestern Wyoming. Nearly all of the diamond core drilling in the Phosphoria formation has been done by mining companies interested in finding and developing phosphate-bearing beds amenable to stripping. The recovery of sludge; and enough core (usually 30 to 60 percent) to identify certain marker beds produced by current drilling practices meets both the primary requirement of mining companies in determining depth of overburden and their secondary need to determine the phosphate content of relatively thick minable units whose general composition and nature are already fairly well established.

Jan 1, 1949

By R. L. Hopkins, H. T. Rall, H. J. Coleman, C. J. Thompson

Two methods were tested for separating sulfur compounds in certain petroleum fractions into types . Such separation is preliminary to identifying the compounds . Each method involved extraction of sulfides from petroleum sulfur concentrates . In the first method , the sulfur concentrate was reacted with methyl - ptoluenesulfonate to form sulfonium compounds from which unreacted portions of the sample were removed by washing with solvent . The sulfides then were recovered by heating the sulfonium compounds with anhydrous triethanolamine . The second method consisted of passing anhydrous hydrogen iodide into a n-butane solution of the sample cooled in dry ice , whereupon the hydrogen iodide adducted with the sulfides to form sulfonium compounds . These adducts separated as crystalline solids or , more frequently , as glassy viscous liquids . The sulfide was regenerated by adding water to the filtered sulfonium compound and was recovered by steam distillation or by extraction with pentane . These methods have been evaluated , using individual pure sulfur compounds and blends of sulfur compounds . They also have been applied successfully to separating sulfides from sulfur concentrates derived from petroleum fractions .

Jan 1, 1964

By B. W. Gandrud

[The Bureau of Mines is conducting an extensive investigation of coal preparation in the Alabama coal fields in cooperation with the University of Alabama coal-mine operators. In this investigation the drainage characteristics of typical coals from the Warrior and Cahaba fields were studied]

Jan 1, 1941

By Louis C. Srichta

The rapid depletion of known high-grade ore deposits of the Tri-State district and the recognized need for development of additional reserves, together with increased interest in open-pit mining of low-grade zinc-lead ores led to Bureau of Mines examination of several abandoned mining areas for possible deposits adapted to strip mining. Examination of the North Empire tract in Cherokee County, suggested that mineralized zones contiguous to previously mined 2e deposits presented probabilities of meeting the requirements for an open-pit mine - hence the tract was selected for further investigation by churn drilling. The zinc-lead deposit on the property is in a sink-hole structure that has been subjected to intense deformation and silicification. Numerous shafts, mine dumps, and surface caves are evidences of exploitation of an extensive area. The reported active mining period was 1895 to 1905. No production records are available, but it is generally stated locally that the value of the mill products exceeded $2,000,000 which represents considerable production, considering the low metal prices of that epoch.

Jan 1, 1950

By H. P. Hamlin, W. A. Grosh

Samples of clays , shales , and argillites from 21 locations were subjected to preliminary bench- scale tests for bloating properties , and several samples were tested for ceramic properties . Samples showing favorable bloating properties were further tested in a pilot - plant - scale rotary kiln . Physical characteristics and concrete -making properties of the bloated products were determined . The Decorah shale from one area made a suitable material for a lightweight aggregate ; however , the limestone layers in the formation must be eliminated or the resulting activated lime must be controlled by quenching .

Jan 1, 1963

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 Roy C. Bartholomae

An accurate characterization of the vibration environment and a vibration qualification test derived from it will be a very useful tool for manufacturers of instrumentation for use on underground coal mining equipment. Recognizing this, the Bureau of Mines sponsored a study wherein vibration levels were measured on mining equipment to form a basis for developing the required vibration test. The data base was composed of 160 samples taken at different positions on a variety of underground machinery. The data were analyzed and presented in a format typical of military vibration qualification tests. The form was shown to be virtually identical to the swept sine test envelope specified in MIL-STD-810B for tracked vehicles.

Jan 1, 1982