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By Robert H. Ridgway

Chromite has been produced commercially for slightly more than a century. Developed, at one time, chiefly as a chemical pigment raw material, it has subsequently found extensive application in other chemical industries - as a refractory material for furnace linings and as the sole source of the metal chromium. For some years prior to 1914, its use as a refractory predominated; but post-war development in alloy steels, principally stainless steels, enhanced the metallurgical demand in the form of ferrochrome with a consequent increase in the demand for chromite. More recently direct reduction of chromite in alloy-steel manufacture has been applied to a limited extent. Alloy steels containing varying amounts of chromium, with or without other alloying elements, now find extensive use in a ride variety of ways - in structural material, machines, industrial equipment transportation by land, sea, and air, sanitary equipment, food preservation, and a multitude of other uses. In recent years chromium plating has had wide application and has become important. industrially, but the amount of raw material consumed

Jan 1, 1936

By William G. Pariseau

Elastic-plastic finite-element simulation of cut-and-fill stoping in deep, narrow veins shows substantial quantitative agreement with field measurements of stope closure and fill pressure made at two mines in the Coeur d'Alene mining district of northern Idaho. The simulation procedure, validated by field data, was used in an analytical study of vein-wall closure and sill-pillar stress as influenced by fill modulus, rock modulus, and premining stress. Ratios of closure and pillar stress in the filled stopes to closure and pillar stress in the unfilled stopes are used as prediction indices for fill performance. In general, the support capability of fill increases dramatically as the ratio of fill modulus to rock modulus approaches 1. A significant reduction in closure .from the open stope--up to 75 percent--occurs with a relatively low-quality 10-ksi-modulus fill (rock modulus of 1,000 ksi). However, a higher quality fill is needed to achieve a substantial reduction in pillar stress from that of the open stope. A 100-ksi-modulus fill reduces pillar stress in both the 36-foot and l6-foot pillars (vein width is 10 feet) by about 50 percent relative to the open stope.

Jan 1, 1976

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 Coal bed 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 Beckley Coalbed, the analysis indicated a linear relationship between hole length and the probability of encountering a discontinuity.

Jan 1, 1982

By R. L. Crosby, L. W. Higley

Magnesium- rich magnesium- aluminum- zirconium alloys in the cast and in the extruded and heat- treated condition were studied to identify the phases present and to determine phase distribution . In cast alloys , two intermetallic compounds were identified : ZrAla by X- ray diffraction ; and Mg₁ Al₁₂ by microscopical observation . Based on microscopical comparisons between the known phases in the cast structures and the phases in the structures of extruded and heat - treated rods , ZrAl₂ and Mg1 , Al12 were identified in the structure of the latter . The presence of these intermetallic compounds in rod specimens could not be confirmed by X- ray diffraction . ZrAl₂ was observed in the structure of extruded and heat - treated rod specimens containing as little as 0.01 weight - percent zirconium . The presence of aluminum restricts the solubility of zirconium in magnesium because of the strong tendency to form ZrAla . This intermetallic compound segregated in clusters of small particles in the matrix of cast alloys , and only slight improvement in distribution was noted when the alloying techniques were varied .

Jan 1, 1964

By T. W. Johnson

The Bureau of Mines, in cooperation with the Natural Gas Department of the American Gas Association, has in progress a study or the flow of natural gas through high-pressure transmission lines. A major problem of this study is to compare the deliveries calculated from the gas pipe-line flow formulas commonly used, with the metered deliveries from pipe lines in operation. In order to obtain such comparisons a series of tests has bean made on 25 operating pipe lines in Kansas, Oklahoma, Louisiana, Arkansas, Texas, and California ACKNOWLEDGEMENTS Study of the flow of natural gas through high-pressure transmission lines was made under the general supervision of H. H. Hill, former chief petroleum engineer of the Bureau of. Mines, H. C. Fowler, acting chief petroleum engineer of the Bureau of Mines, N. A. C. Smith, superintendent of the Bureau of Mines Petroleum Experiment Station at Bartlesville, Okla., and T. Brandenthaler, chief of the oil and gas action of the Bartlesville station.

Jan 1, 1929

By A. W. Frolli

This paper, describing the mining and reduction methods and costs at the Oceanic quicksilver mine, is one of a series of similar reports being prepared by the Bureau of Mines on various mines in the United states. The property, which is owned and operated by the Anglo American Mining Corporation, Ltd., is 5 miles east of Cambria, San Luis Obispo County, Calif. It lies in a region of steep hills and sharply incised canyons on the west slope of the Santa Lucia Range at an elevation of about 500 feet above sea level. The climate is ideal for living and operating conditions. A 40-mile paved highway connects the mine with San Luis Obispo, the nearest convenient railroad town.

Jan 1, 1937

By G. M. Potter, S. J. Hussey, R. Havens

The Artillery Peak manganese ores , from one of the largest known manganese deposits in the United States , present a difficult problem in concentration because they are low-grade and the association of manganese and gangue minerals is intimate and complex. The known size of this deposit has justified investigation of processes such as leaching, wherein preliminary enrichment of the original feed might be advantageous .. Therefore , the ore-dressing studies on Artillery Peak ores were carried on with the object not only of making directly marketable manganese products but also of removing acid-consuming calcite and raising the grade of ore for leachingplant feed . Owing to the extent of the deposits , test work was carried on at the Salt Lake laboratories in considerable detail on several lots of ore of varying composition . This paper summarizes the results obtained from laboratory testing of four samples obtained by engineers of the Mining Branch from the Maggie Canyon area of the Artillery Peak deposit . Also included are results obtained from testing one sample of Chapin Group ore , which was considered representative of numerous very low-grade ores submitted from the Artillery Peak district . During the course of the investigations , many data were obtained and compiled , but for the sake of brevity , data of secondary importance have been omitted or condensed and only those tests giving the more pertinent results are discussed in detail ...

Nov 1, 1947

By R. Blickensderfer

Several thin film absorber stacks with spectrally selective characteristics were developed by the Bureau of Mines. The stacks consisted of a silicon thick film or a zirconium compound thin film on a reflective thin film of silver. The zirconium absorber films, with the general formula ZrCxOyNz, were prepared by reactively sputtering zirconium or zirconium carbide in argon with small amounts of oxygen, nitrogen, or both, or by oxidizing zirconium films in air. A few similar types of films were prepared from titanium. The short-wave absorptance over the solar spectrum, a(s), and thermal emittance at 600 K, e(600 K), of the solar absorber stacks were calculated from room-temperature reflectance data. The values of a(s) ranged from 0.47 to 0.93, e(600 K) from 0.49 to 0.034, and the ratio a(s)/e(600 K) from 1.7 to 34. The specimen with the best combination of properties, a ZrNx-Ag stack, had a solar absorptance a(s) of 0.85 and a ratio, a(s)/e(600 K), of 24. The effect of film thickness and composition on spectral selectivity was determined. An emissometer for measuring normal total emittance up to 800 K and a method for determining a (s), e(T) (hemispherical), and a(s)/e(T) using simulated solar radiation are described. A calorimetric method for measuring a(s) and e(T) (hemispherical) at elevated temperature is also described. Measurements made on several specimens agreed favorably with calculated values.

Jan 1, 1976

By H. D. Jacobs

The Bureau of Mines developed a concentration method to upgrade and utilize marginal natural or direct-shipping iron ores and fine-grained lean iron ores. Presently these ores receive little beneficiation and accordingly have low iron-silica (Fe-Si02) ratios. Ore samples were roasted with equal weights of solid reductant at 1,100° C for 1 hour to metallize the iron and for an additional hour at 1,200° C to promote grain growth. Concentration was effected by crushing and screening techniques and/or wet magnetic separation. Sized concentrates (minus 4 plus 35 mesh) derived from crushing-screening processes contained from 80 to 85 percent iron that was 90 percent metallized. Iron-silica ratios as high as 12:1 and iron recoveries from 75 to 94 percent were obtained. The sized concentrates were judged suitable for use as blast furnace feed. Minus 200-mesh metallized concentrates derived from roasted minus I-inch plus 8-mesh ore fractions and magnetically concentrated contained 90 percent Fe and 4 percent or less Si02, chemically qualifying them as feed for electric furnaces. Roasting minus 8-mesh ore with hydrogen, then magnetically concentrating it, produced iron concentrates containing 57 percent to 67 percent Fe and 3.6 percent to 8.4 percent Si02. The concentrates having Fe-Si02 ratios ranging from 8:1 to 12:1 were considered adequate for use as blast furnace feed. Overall iron recoveries for the 12 ores tested ranged from 56 percent to 94 percent with an average iron recovery of 86 percent.

Jan 1, 1969

By Jennifer S. Riefenberg

The U.S. Bureau of Mines conducts basic and applied research related to predicting, eliminating, and/or controlling rock bursts in underground hard-rock mines and coal bumps in underground coal mines. An important element in this research is the development of a reliable and efficient microseismic source location technique. This report presents the results of a Bureau study to develop and evaluate a new algorithm to locate microseismic events based on the Simplex method, a powerful linear programming technique. The technique was tested on both field data and simulated data. Microseismic event source locations obtained with this new Simplex-based algorithm were shown to have less error than those locations obtained using a least squares method. It was concluded that the Simplex approach to source location of microseismic events can be used effectively in microseismic monitoring.

Jan 1, 1989

By Edward L. McHugh, Charles Sabine, Jami Dwyer, David G. Long

Slope failure accidents were responsible for about 12% of U.S. surface mine fatalities between 1995 and 2003. Small surface movements on a mine highwall may be precursors of failure that, if detected, could provide sufficient warning to enable workers and machinery to be withdrawn to safety. Radar interferometry offers the necessary precision to detect these movements. Radar has some advantages over other methods in its ability to cover large surface areas for true two-dimensional monitoring day and night under almost any weather condition. Radar’s active transmit/receive mode of operation provides for more direct sampling than do passive optical methods that depend on solar illumination. Improvements in microprocessor speeds and capacities have led to the development of a number of small, portable, ground-based systems; such systems are now being deployed at several locations around the world. As part of an ongoing study of monitoring technologies, researchers from the National Institute for Occupational Safety and Health and Brigham Young University, Provo, UT, cooperated to assess the feasibility of using interferometric radar to monitor mine slope stability. Field tests of a device incorporating prototype equipment were successful in that small, centimeter-scale displacements on rock slopes were detected.

Jan 4, 2006

By Maria I. DeRosa

This Bureau of Mines report describes the Automated Breathing Metabolic Simulator and its hardware and software systems with emphasis on the role exerted by the software program subroutines in controlling the hardware mechanisms during the simulation of man's respiratory and metabolic functions.

Jan 1, 1978

By V. E. Erwin, W. W. Adams

"Production of explosives for industrial use in,the United States during 1934 continued the upward trend begun in 1933 from the low-level output of 1932, and the output in 1934 was only slightly less than in 1931.Reports to the United Stated Bureau of Mines from companies engaged in the manufacture of industrial explosives showed that the quantity of explosives manufactured in the United States and sold during 1934 for use within the various States was 314,767,922 pounds - 23 percent more than in 1931.Production during 1934 included 39,207,845 pounds of permissible explosives 5 206,625,027 pounds of high explosives other than permissibles, and,68,935,050 pounds of black blasting powder of which 37,192,700 pounds were in granular form and 31,742,350 pounds in pellet form. These figures represent an increase over 1933 of 15.6 percent for permissible explosives, 30.9 percent for other high explosive, and 7.4 percent for black powder.Coal-mining operations were the chief consumers of permissible explosives; 99 percent of the total output in 1934 was used, in coal mines. The proportion used by bituminous mines was 59 percent and by anthracite mines 40 percent. Coal mining was likewise the principal consumer of black blasting powder, taking 88 percent of the total sales during 1934; of this proportion, bituminous mines received 78 percent and anthracite mines between 9 and 10 percent. Consumers of high explosives other than permissibles were more varied; the reports showed that 11 percent of the total quantity sold was for coal mining, 22 percent for metal mining, 17 percent for quarrying and nonmetallic-mineral mining, 46 percent for railway and other construction work, and 4 percent for all other purposes."

Oct 1, 1935

By Constantine C. Popoff

"INTRODUCTION AND SUMMARYDuring 1946 several high-grade limestone deposits in western Washington were examined by the Bureau of Mines. This report presents the data obtained from investigation of the Sauk Mountain deposits in east-central Skagit County, Washington.The investigation consisted of transit and topcgraphic surveys and sampling. The areas selected for sampling were first cleaned by blasting; channel samples up to 40 pounds were cut where practical. Chip samples averaging 30 pounds were taken where channel samples could not be cut. A total of 21 samples in the Sauk Mountain area were taken and. analysed. The locations of the samples are shown in figures 2 and 4, and the analyses are listed in tables 1 and 2. This investigation is a part of a long-range program of general investigation of mineral resources for future industrial development of the Pacific Northwest. The Sauk Mountain deposits were investigated for the purpose of disclosing now sources of high-purity limestone, which could be mined and shipped at low cost to Seattle and other industrial cities in the Pacific Northwest."

Oct 1, 1948

By J. Tomlinson

Shuttle car trailing cable splices were tested for resistance to failure upon being subjected to repeated bending, abrasion, and tensile shocks using a new testing method that closely simulates shuttle car induced stress. The results show that under normal stresses, splices can be made to withstand the equivalent of three months of operational use. Restoring the tensile strength to the conductors is found to be as critical as restoring flexibility. Splices in which the conductors are of slightly unequal length did not present as serious a workmanship problem as previously thought since test results show that the conductors tend to equalize when longer cables, in contrast to short cables employed in previous testing methods, were used. Dynamic recordings of cable tensile stresses are presented for a shuttle car and the new simulated testing method. Two simple but effective methods for removing insulation using a knife and a pair of pliers are described. None of the designs tested for a sacrificial splice covering were satisfactory.

Jan 1, 1979

By T. L. Marchewka

As part of its program to conserve the Nation's natural resources by developing improved performance materials, the Bureau of Mines, U.S. Department of the Interior, in cooperation with the U.S. Department of Energy, has conducted an investigation of materials of construction able to withstand the high temperature and hostile environments encountered in coal gasification units. Refractory pipe liners are required when extremely hot gases or abrasive solids are transported between processing units in the gasification plants. One promising technique for producing refractory pipe (or refractory pipe liners) is centrifugal casting. For this study, the effect of processing variables such as workability, additives, reinforcement and spinning time, and centrifugal force were evaluated using four commercial refractory concretes. In addition, data on characteristics such as strength, density, abrasion, and spalling resistance of 5-inch-diam refractory pipe were developed. Techniques for forming large-diameter (19-inch) refractory pipe also were evaluated. The test results indicated that all four refractory concretes could be made into strong, homogeneous pipe, but that optimum casting parameters had to be determined for each specific composition. The investigation revealed that the major controlling factor in the production of the centrifugally cast pipe was the workability of the refractory concrete.

Jan 1, 1979

By C. M. McCulloch, Maurice Deul

A geologic study of Mines 32 and 33 in Cambria County, Pa., was conducted as part of a methane control research program. Areas of high methane emission and roof instability are encountered which are related to the structural and stratigraphic features that characterize the geologic setting of these mines. Locally the folds trend N 20° E ±2°, the direction of the butt cleat in the Lower Kittanning coal. The face cleat strikes at N 69° W ±2° and the systematic rock joint in the surface bedrock strikes N 67° W ±2°This suggests that a directional stress oriented N 70° W produced the folds and influenced the directions of coal cleat and systematic joint sets. Analysis of SLAR indicates three directions of prominent regional lineation: N 39° E, N 31° W, and N 70° W. Little gas was encountered during development mining; large volumes of gas are encountered when roof falls. Most of the gas comes from strata above the mined coal; therefore, to control methane, roof instability must be controlled. Roof falls and high rates of methane emission are most likely where less than 30 feet of many thin layers of limestone, shale, and sandstone occurs between the Lower Kittanning coal and the next coal and in zones along the margins of a sandstone channel.

Jan 1, 1973

By Parviz F. Rad

The increased use of tunnel boring machines (TBM) has stimulated laboratory research to optimize the cutting parameters of these machines with the objective of increasing machine efficiency and penetration rate. Laboratory-scale rock cutting experiments have succeeded in identifying many of the important parameters involved in rock-cutter interaction. Although scaling factors may be required to apply the results directly, the concepts developed can be used qualitatively as design guidelines for boring machines. The Bureau of Mines Twin Cities Mining Research Center has recently developed a large-scale rock cutting device (RCD) that will simulate many of the operating parameters of the tunnel boring machines in the laboratory under a controlled environment. The results of the experiments with this device will be directly applicable to the design of TBM's.

Jan 1, 1973

To develop effective noise controls for continuous min-ing machines (CMMs) to reduce worker noise exposure. Background Noise-induced hearing loss (NIHL) is an occupational illness caused by chronic exposure to excessive sound levels. For underground coal mine workers, NIHL continues to be a serious health issue. Analysis of hearing loss data suggests that by retirement age, 70%?90% of U.S. coal mine workers will have a hearing impairment. Operated in the confined spaces of underground mines, large industrial mining equipment often produces sound levels that can be harmful to workers. Of all equipment used in underground coal mining operations, CMMs account for the most noise overexposures. To reduce the occurrence of noise over-exposures, engineering noise controls must be developed for the CMM.

Sep 1, 2008

By D. W. Bridges, S. R. Borrowman

Thorium and yttrium oxides were recovered from siliceous ores of the Powderhorn , Colo . , area . Processing comprised ( 1 ) acid curing and subsequent ( 2 ) acid baking , ( 3 ) leaching , and ( 4) solvent extraction of thorium , using a primary alkylamine , and yttrium , using di - 2 - ethylhexyl phosphoric acid . About 95 pct of the contained thorium and yttrium was recovered from ore containing 1.2 pct Th02 and 0.5 pct Y₂ 03. The thoria product was 99 pct Tho ; the yttria product was 77 pct Y₂ 03. A 150 - to - 1 concentration ratio was effected on the latter , but some contaminating lanthanon - group oxides remained .

Jan 1, 1964