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By W. A. Calhoun

The purpose of this investigation was to develop a procedure for removing excess iron from representative samples of bauxite ore from the Quapaw deposit of American Cyanamid Co., Saline County, Ark., in order to produce a beneficiated ore suitable for use in the alum industry, At the request of the sponsoring company, the samples were reduction-roasted at 800° C. and then magnetically separated. Although some rejection of iron was effected under these conditions, the general results were not satisfactory, A much more successful procedure, from the standpoints of both rejection of iron and recovery of alumina, consisted of a short (l5-minute), low-temperature (400° C.) oxidizing roast, followed by a 2-minute interval in a hydrogen atmosphere, then cooling to room temperature, and, finally, high-intensity magnetic separation to remove the iron.

Jan 1, 1957

By W. R. Huff

Yield stress and plastic viscosity values, determined from shear rate-shear stress relationships, were found to be a linear function of coal concentration for coal-water slurries containing 40, 45, 50, and 55 weight-percent of powdered coal. In the laminar region, the flow is described by an equation derived from the fact that the square root of the shear stress varied linearily with the square root of the shear rate. In the turbulent region, the friction factor was found to be inversely proportional to the velocity to the 0.12 power.

Jan 1, 1965

By W. H. Young

THE BITUMINOUS coal and lignite industry increased substantially in 1962, compared with the 1961 figures. The major items of production, consumption, exports, and productivity increased. However, certain key items declined. The steady upward trend in mechanization failed to materialize for the third year; the percentage of total tonnage mechanically loaded remained the same as in the 2 previous years; and the tonnage mechanically cleaned was smaller than in the previous year. The percentage of total production mined by stripping and by augers increased slightly. Most significant was the continued decline in average value and employment. Production.-The output of bituminous coal and lignite in the United States in 1962-422 million tons-was 5 percent greater than the 403 million tons produced in 1961. Production was greater in 1962, owing largely to expanded consumption by the electric utilities and to more exports.

Jan 1, 1963

By Jerry W. Ramsey

The Bureau of Mines studied two Pennsylvania anthracites using low-temperature carbon dioxide adsorption. A modified form of the Brunauer-Emmett-Teller equation was used to calculate specific surface areas. Two mesh sizes of each anthracite were used to determine how gamma irradiation at 106 and 108 rads, both in vacuum and in the presence of air, affected the carbon dioxide surface areas. Results show that anthracites have a system of pores that are essentially all interconnected rather than isolated; that anthracites differ from one another in specific surface, which may correlate with density; and that irradiation in vacuum has no discernible effect on specific surface of anthracite, but irradiation in air does produce changes in specific surface.

Jan 1, 1966

By Allen L. Frank

A portable radon diffusion chamber has been tested with electrical collection of the radon daughter nuclei for enhancement of sensitivity. The detector size was small enough to be worn suspended from the belt. With a battery-supplied high voltage the sensitivity was found to be 1.43 tracks/cm2 per pCi-hr/l of ambient radon at Sot relative humidity. The track densities on the surfaces of the CR-39 plastic nuclear track detectors were found to be non-uniform, making difficult the determination of average densities with high accuracy. The fabrication of electrets for use in the detector was investigated in accordance with published techniques with negative results.

Jan 1, 1983

By Lester G. Morrell

THE WORLDWIDE economic expansion that has characterized the first 3 years of the 1960's continued through 1964 and was reflected in North America by strength in the industrial economy of the United States, which again was dominant. Advances in production were recorded in virtually all industries, including the mineral industry; 1964 mineral production established a new high, 5.4 percent above the previous peak recorded in 1963. However, the percentage increase in value of North American mineral production was slightly below overall economic growth. For industry in general, consumer demand held firm throughout the year and overall commodity prices averaged 2 percent higher than in 1963. Wages and salary payments also were up. With the single exception of the dock strike in the United States, the year was free of serious labor troubles and unemployment in both Canada and the States was at a low level. Despite the Viet-Nam situation, relatively tranquil international relations contributed to the forward movement of North American business. Total gross national product (GNP) for Canada and United States, in current dollars, was estimated at US$672.2 billion; 6.8 percent above the previous year's figure. Combined national income in 1964 amounted to US$546.9 billion, which was nearly 7.0 percent more than in 1963. In 1964, gains were recorded in each of more than 50 metals, nonmetals, and fuels commodities that comprise the North American output. The greatest category increase was 13 percent in metals, which was in part attributable to the 14 percent rise to a new record in value of iron and steel in United States, a 29 percent higher value of Canadian iron ore and a 57 percent rise in Canadian zinc. Despite a moderate decline in prices of iron ore and iron and steel products, generally favorable markets and rising prices for metallic ores and metals were a stimulant to the metals industry. Nonmetallic materials, with a total value in excess of US$5.25 billion were 7.3 percent higher than in 1963. High levels of highway and building construction and expanding demand for fertilizers and chemicals continued throughout the year. Noteworthy output increases were recorded for lime,

Jan 1, 1966

By Christopher Mark

Since it was first introduced, the Coal Mine Roof Rating (CMRR) has been widely accepted as a tool for geologic characterization and mine planning. This paper discusses the application of the CMRR to another practical ground control problem. Extended cuts (cuts greater than 6 m (20 ft) in length) are commonly used with remote control continuous miners. Extended cuts can greatly increase productivity, but they have been associated with a number of fatal roof fall accidents. When extended cuts are attempted in weak roof, the roof may collapse before it can be bolted, causing hazardous conditions. Until now, it has not been possible to predict where conditions may not be suitable for extended cuts. In this study, data on the CMRR and extended cut experience were collected at 36 mines in 7 states. It was found that when the CMRR was greater than 55, deep cuts were routine in nearly every case. When the CMRR was less than 37, extended cuts were almost never taken. Between 38 and 55, extended cuts were feasible sometimes but not others. The data also shows that extended cuts are less likely to be stable if either the entry span or the depth of cover increases.

By G. S. Rice

[This paper describes preliminary tests at the Bureau's Experimental Mine to determine, under conditions that may prevail ira bituminous coal-mine heading, how small a quantity of fire damp may bring coal-dust into suspension and ignite to it. The results show that the explosion of as little as 150 cubic feet of an explosive mixture of gas and air containing 9 per cent natural gas may start a disastrous explosion Of coal-dust. This is a very small volume, of gas, to cause such a result. Let us suppose that this amount of exclusive mixture, was at the face of an entry which was 10 feet wide and the face was overcut to a depth of 6 foot and an upper layer of coal 2 1/2 feet thick had been removed, the recess so made would save a volume of 150 cubic feet. Furthermore, only 13 cubic feet of pure methane is needed in this volume to produce this 9 per cent explosive mixture.]

Jan 1, 1930

By E. A. Pelczarski

Initially, the objective of this contract was to develop a PWSCSR that could meet proposed criteria (that were different from 30 CFR 11(Title 30 of the Code of Federal Regulation part II) and that would be less than twice the size and weight of a filter self rescuer. This objective was met. Consequently, the original contract was extended to develop a PWSCSR that would meet existing CFR-30 criteria within the same size and weight constraints. This resulted in the development of a PWSCSR (the SR-100) that received NIOSH/MSHA approval (TC-239). This report presents a historical discussion of the design and development of the SR-100 as developed by CSE Corporation under Bureau of Mines contract number H0368013. The technical parameters and the test results of NIOSH/MSHA 30 CFR 11 certification are also presented.

Jan 1, 1990

Researchers with the National Institute for Occupational Safety and Health (NIOSH) have developed a training module to educate both new, inexperienced miners as well as veterans on important issues related to self-rescue and escape procedures. These include: (1) physical and environmental conditions that can be encountered in a mine after a major explosion, (2) knowledge of emergency meeting locations and escape routes, (3) the importance of using self-rescuers, even in seemingly clear air, to keep the lungs isolated from contaminants, and (4) why miners should not go off to look for others who are missing. In addition, the module may stimulate miners to think about and discuss mine explosions and the devastating effects of such an event.

May 1, 2009

By John D. Corrick

Three species of chemosynthetic iron- and sulfur-oxidizing autotrophic bacteria have been isolated from the leaching waters of copper mining areas. These species are: The sulfur-oxidizing Thiobacillus concretivorus, the iron-oxidizing Ferrobacillus ferrooxidans, and a sulfur- and iron-oxidizing bacterium closely resembling Thiobacillus ferrooxidans, INTRODUCTION Among several suggested new processes for treating marginal ores in the United States, none is more intriguing than the possibility of extracting metals from low-grade materials by the action of microorganisms One phase of a Federal Bureau of Mines investigation toward developing such a procedure was to isolate and identify specific chemosynthetic iron and sulfur. oxidizing autotrophic bacteria native to certain domestic copper deposits where leaching is practiced. The bacteria or microorganisms considered important to this investigation are those capable of producing solutions of ferric sulfate and sulfuric acid. Solutions of this type are excellent solvents for some copper minerals By establishing the presence of these bacteria at certain copper-leaching areas, strength would be given to a theory that microbial activity is partly responsible for the oxidation that takes place at these areas. Their presence also advances possibilities for controlled use of microbial action in metal extraction processes. Leathen4/ has demonstrated that one of the chemosynthetic iron-oxidizing bacteria, Ferrobacillus ferrooxidans, can oxidize 200 parts per million of ferrous iron to the ferric state in 3 days,

Jan 1, 1961

By W. H. Eddy

The Bureau of Mines conducted laboratory batch and continuous flotation processing tests on waste granite fines from South Carolina to determine the possibility of recovering high-quality feldspar and glass sand. Three flotation systems were used for removal of the iron-bearing biotite: Two employed an alkaline anionic-cationic circuit and the third employed an acid cationic circuit. Commercial-grade products were obtained when the remaining biotite was magnetically removed from the feldspar and quartz concentrates. Continuous flotation processing yielded a feldspar concentrate containing, in percent, 3.60 Na20, 5.60 K20, and 2.25 Ca0, with recoveries of 75.3, 66.6, and 72.6 percent, respectively. The feldspar tailing was high quality glass sand containing 98.0 percent Si02 and 0.025 percent Fe203; about 60 percent of the quartz was recovered.

Jan 1, 1972

By Earl R. Maize

This is the first of a series of reports dealing with development of a method of strengthening bituminous-coal-mine roof. Later reports will describe the progress made with injecting high cohesive and adhesive bonding agents into bedding planes and mine tests of roof strata strengthened by the bonds formed. The concept of strengthening roof strata in coal mines by inserting steel rods in the form of bolts has been widely accepted by the coal industry. The benefits of increased production and safety derived from this type of roof support has more than justified the increased cost of roof bolting. However, not all coal-mine roof structure is amenable to this type of support, and failures occur owing to the heterogeneity and variable character of mine-roof strata.3/

Jan 1, 1957

By Clark R. Neuharth

To assess the supply status of ultra-high-purity silicon for national defense needs, the U.S. Bureau of Mines conducted a general study of the availability of materials and processing technology for silicon used in the manufacture of infrared (IR) detectors from raw materials to the highly advanced device state. The United States possesses all of the raw materials and processing technology for IR detector-grade silicon production, but does not produce at all of the processing stages on a regular basis. Consequently, the United States continues to rely on foreign sources for some of these critical materials.

Jan 1, 1989

By John W. Buch

Hydraulic cutting tests made on samples of Pennsylvania anthracite (3,700 psi and 260 gpm) were promising enough for the Bureau to establish a full scale experiment in an anthracite mine. Water pressure and quantity for mining anthracite were arbitrarily established at 5,000 psi and 300 gpm (1,000 hp). For full-volume flow, hydraulic pressure is controlled by orifice size with the displacement pump. The hydraulic jumbo was designed for maneuvering on pitches from 0° to 20° in any direction and for a coalbed ranging in thickness from 10 feet 6 inches to 15 feet. All motions of the jumbo are by oil hydraulics. Jet flow is controlled (start-stop) at the face, through an interlocked pushbutton system. One button is in the operator's cab; one, at the pump station; and one (a safety shutoff), near the mining face. To December 1962, 7,400 tons of bed material had been mined at an average rate of 0.800 ton per minute, with an average power requirement of 14.125 kilowatt-hours per ton. In January 1963, the objective was changed from an engineering-development basis to a research basis--to determine, ultimately, the most efficient level of operating characteristics for maximum response, as measured by mining-out rate. This research phase of the project is not yet complete, but conclusions, and the method of arriving at them, will be made the subject of another Bureau publication. It should be noted that as of December 1963 nearly 13,000 tons of bed material had been mined, at rates as high as 1. 3 tons per minute for a complete face advance.

Jan 1, 1965

By H. Tomlinson

The development of the Sevier Valley Coal Co.'s mine marks the opening of the Salina Canon coal district in Utah. The mine is favorably located with respect, to the existing markets of the West, and if the present estimates of the amount of workable coal in it are accurate it has many Important advantages in favor of its development. This mine is situated 18 miles east of the town of Salina, Sevier County, Utah, which at present is the nearest shipping point oh the Marysvale branch of the Denver & Rio Grande Western Railroad, and is about 152 miles south of Salt Lake City, which is the distributing center for much of the coal from the Carbon - Emery coal field and is the place from which nearly all Utah coal shipped to San Francisco and points on the northern Pacific coast has a common haul.

Jan 1, 1930

By John Nagy

Limited experiments in the laboratory with specimens of mine rock from a Virginia bituminous coal mine indicate that natural gas-air mixtures can be ignited by sparks generated by rubbing friction of sandstone against sand-stone, shale against sandstone, sandstone against (roof-bolt) steel, and shale against steel. Such sparks, generated during a roof fall, may have initiated a recent gas explosion in this Virginia mine, although this cannot be stated with certainty. No ignitions of gas were produced by sparks or heat generated by impact friction between mine rocks or steel, during tension breaks of roof bolts, or by pull tests of roof bolts through their washers and roof plate. However, this negative result of limited experiments does not preclude the possibility of gas being ignited by these conditions.

Jan 1, 1960

By Henry C. Meeve

This report describes work done in the Creede Mining district, Mineral County, Colo., in 1965-66 as a part of a Bureau of Mines study of the silver production potential of the United States. The ruining history of the district is briefly covered, and representative former and current mining operations are described. Mining and milling costs of the Emperius Mining Company's operation are given in some detail as being representative of the cost of mining typical Creede ore bodies under current technology. An estimate of the silver reserves and resources of the district is presented, subject to many uncertainties stemming from inaccessibility of old workings, lack of mining records, and low level exploration activity, all of which limit the opportunity to accurately evaluate ore potential. The report concludes with an analysis of future silver production trends in the Creede district. An increase of silver production to as much as I million ounces yearly is projected, possibly starting in 1969. As long as ore bodies in the zone of enrichment, in which silver is a major constituent, contribute a substantial part of Creede production, silver price will affect overall production rates appreciably. As the richer are bodies become depleted, an increasing portion of production again will be coming from primary sulfide ores in which silver is a byproduct of lead and zinc. When this occurs, the level of silver production will be governed chiefly by lead and zinc production and prices and can be expected to decline to the 1960-66 level, which amounts to an average of 240,000 ounces per year.

Jan 1, 1968

By Charles L. Kimbell

Available statistics on 1991 worldwide consumption of selected non fuel mineral commodities shown in table 12 indicate downturns for all but 3 of the 15 listed commodities. It should be stressed that in most instances, the consumption declines were primarily the result of lower levels of use in the former U.S.S.R. and the former centrally planned economy nations of Eastern Europe. However, several commodities suffered use cutbacks in market economy countries. In the case of the nonferrous metals covered In the table, the differences in performance between market economy countries and the former centrally planned economy states are immediately evident from the table itself. Among these important commodities, refined lead, primary magnesium, and refined tin registered downturns for market economy countries as well as among the centrally planned economy countries. Also notably, cadmium use showed no significant change from 1990 levels in either group of countries. Global consumption of iron ore fell by 3.4 % or about 31 million tons, and this was a greater decline than that logged for production of marketable iron ore and related products, which was down by only 3.0% or almost 28.2 million tons. Thus, it would seem that for another year there was a net addition to stocks. The 1991 drop in iron and steel scrap use was about 5.5 % or about 18 million tons, on the percentage basis somewhat greater than the 4.8% or 36.9 million ton drop in global steel production. Although consumption of iron ore and iron and steel scrap are not broken down by region in table 12, it seems almost assured that the pattern of 1990 continued into 1991: drops in use in the former U.S.S.R. and Eastern Europe were the overwhelmingly dominant declines and accounted for much, although not all, of the global decline, whereas among market economy countries as a group, there were upturns for both materials. On a global basis, it would appear that the slight shift in the ratio of pig iron to scrap in steel furnace charges noted in 1990 continued into 1991, this shift being toward a slightly larger proportion of pig iron with a corresponding decline in the share accounted for by scrap.

Jan 1, 1993

By F. W. Hoertel

The effects of certain process variables on the grain size, grain type, and microhardness of vapor-deposited tungsten were established, and the near-optimum parameters and the efficacy for the vapor deposition process were determined. No significant change in the grain size or microstructure resulted from ultrasonic vibration of the substrate during deposition, from variations in the hydrogen (H2) to tungsten hexafluoride (WF6) ratio, or from small increases in reaction-chamber pressure. Near-optimum conditions were continuous deposition at atmospheric pressure, a deposition rate of 2-mils thickness/square inch of substrate area/hour, a temperature of 5500 C, and a hydrogen to WF6 ratio of 4:1. The addition, individually, of about 2 volume-percent of butane, 24 volume-percent of carbon dioxide, or 4 volume-percent of propane to the hydrogen and WF6 mixture produced deposits with the finest grain size for each gas. A corresponding increase in microhardness accompanied the decrease in grain size. The addition of gases did not alter the columnar microstructure found in vapor-deposited tungsten.

Jan 1, 1966