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This Bureau of Mines publication summarizes the industrial minerals industry of Idaho. It contains information on 119 principal deposits of 21 commodities in the State and describes the institutional and infrastructural factors affecting mineral development.

Jan 1, 1991

By J. Bennetts

As part of its mission to develop technology that will help increase the supply of critical and strategic minerals from domestic resources, the Bureau of Mines has investigated methods for beneficiating platinum-group metal ores from the Stillwater complex, Montana. This report presents the result of a bench-scale study employing froth flotation to recover a sulfide concentrate containing platinum-palladium values from a mineralized gabbro. Best results were obtained with a flotation scheme utilizing a mercaptobenzothiazone collector and sulfuric acid. Rougher concentrates containing approximately 11 oz Pt-Pd/ton and 90 pct of the metal values in the ore were obtained. Subsequently, cleaner concentrates containing approximately 26 oz Pt-Pd/ton and between 80 to 85 pct of the Pt-Pd values in the ore were prepared.

Jan 1, 1980

By W. W. Adams

The accident-prevention record of the coal-mining industry in the United States was more favorable in 1936 than in 1935, both from the standpoint of the relative safety of the individual miner on the job and of the price in life and limb that the Nation paid for its year's supply of coal. The increase in relative safety of the individual miner was indicated by a lower death rate and a lower injury rate than in the preceding year per million man-hours of exposure to the hazards of mining; that is, per million hours of work performed by the employees. (See table 1.) A reduction in the price in life and limb that the Nation paid for a year's supply of coal was indicated by a smaller death rate and a smaller injury rate per million tons of coal produced. Thus the individual miner was a better insurance risk, as far as accidents were concerned, in 1936 than in 1935, and a ton of coal used in the homes and industries of the country represented less human suffering than in 1935. The two points of view are distinct, and both should be kept in mind when considering accidents and safety in coal mining or in other industries. More men were employed in 1936 than in 1935, and more workdays were available for the individual miner. Large gains were also made in the total number of man-shifts and man-hours worked in the industry as a whole. In number of tons of coal mined, 1936 showed large gains over 1935. Moreover, the average output of coal per man-hour worked was higher in 1936 than in 1935. All of these gains were made without lengthening the average number of hours of work per man per day.

Jan 1, 1939

By John Gross

From the time when man first pounded one rock upon another or used heat and sudden chilling with water to disintegrate rock, the art of crushing advanced but slowly to the mule-driven arrastre and the Chilean mill stage until the advent of power-driven appliances made material progress possible. The combined efforts of manufacturers and operators have made modern machines highly efficient mechanically. Although marked progress has been made along mechanical lines, the theory and conception of underlying principles have not advanced so rapidly. This lack of advance in theory may be attributed to the unfortunate situation resulting from the controversy as to whether the Rittinger or the Kick law is applicable to crushing. Many pages of the technical literature are burdened with theoretical discussions in favor of one or the other of these laws, which have tended to cloud rather than to clear the atmosphere.

Jan 1, 1938

By G. R. Strimbeck

Experimental work is report on the gasification of 90-percent through 200-mesh, strongly coking Sewickley-bed coal with oxygen and with steam in three temperature ranges, namely, 2,700° to 3,400° F., 1,600° to 2,000° F., and 230° to 250° F. Thirty-one runs have been made, during which 56,000 pounds of coal have been charged to the generator at feed rates of 200 to 450 pounds of coal per hour. The average results, not the optimum results, are given in the following tabulation:

Jan 1, 1950

By M. M. Fine

A process for simultaneously reducing and indurating iron are pellets was developed by Bureau of Mines laboratory research and confirmed on a continuous pilot plant basis. Moist iron are concentrate was balled, mixed with solid reductant, and heated at about 1,100° to 1,150° C. On a small scale, a variety of concentrates and fuels were utilized successfully. The pilot rotary kiln tests were limited to natural magnetite, synthetic magnetite, lignite, and anthracite. In both cases, partially reduced pellets with excellent physical properties were regularly produced with average analyses of at least 80 percent total iron and 60 percent or more metallic iron. These and other prereduced pellets were smelted in the Bureau's experimental blast furnace facility, Bruceton, Pa. With prereduced spheres comprising 85 percent of the burden, the coke rate was approximately half that with standard oxide pellets and production of hot metal was increased by 75 percent. Economic appraisal of the cost of making hot metal indicates that reduced pellets could be more profitable than any other iron raw material in both investment capital and daily cost of operation.

Jan 1, 1970

Study to develop a new and more cost effective equipment system, incorporating a winch-pulled dozer blade, for leveling spoil and performing reclamation of area strip mines.

Jan 1, 1975

By W. E. Pittman

The Bureau of Mines, as part of its Health and Safety Technology Program, is conducting research on the use of ground penetrating radar (GPR) for mine hazard detection. GPR offers a possibility of mapping immediate below-surface geologic conditions, including faulting and other anomalies, thereby exposing potential safety hazards to miners. This report summarizes a literature review of the current status of GPR research in and outside the Bureau.

Jan 1, 1984

By A. C. Fieldner

"INTRODUCTION In a previous report3 prepared for the American Gas Association, the influence of washing coal on coke properties and on gas and by-product yields was discussed on the basis of answers to questionnaires sent to coke-oven superintendents and a review of the literature on the subject. This review indicated that the elimination of free impurities by cleaning coal improved coke quality by (a) reducing ash and sulphur, (b) decreasing clinker trouble in burning the coke, (c) diminishing cross fractures in the coke, resulting in greater resistance to breakage on handling, and less small coke and breeze, and (d) greater uniformity in chemical composition and physical properties of coke. Washing also reduced the sulphur in coke and gas and increased the yield of gas and by-products per ton of dry coal charged.This paper is supplementary to the previous report and presents some experimental data obtained with Pittsburgh bed coal from Pennsylvania and Mary Lee bed coal from Alabama.ACKNOWLEDGMENTSGrateful acknowledgment is made to F. J. Pfluke, of the Rochester Gas and Electric Cc., of Rochester, N. Y., for the plant test data on screened lump and washed coal; and to Ray W. Arms, Manager of the Coal Cleaning Department, of Roberts & Schaefer Co., of Chicago, for the data on effect of air cleaning."

May 1, 1931

By L. W. Higley

It is estimated that well over 20 million lb of chromium and 8 million lb of nickel, plus other metal values, are diverted annually to furnace dusts, mill scale, and contaminated swarfs in the domestic stainless and other specialty steelmaking industry. Little inroad has been made toward the in-plant recycling of these wastes to reclaim the metal values. The Bureau of Mines has devised a process for recovering about 90 pct of the chromium and molybdenum and well over 90 pct of the nickel and iron from stainless steelmaking furnace dusts, swarf, and mill scale. Other metals such as manganese are also recovered. Initial laboratory results were confirmed and expanded to include a wide variation of stainless steelmaking waste mixtures. Later experiments have included specialty steelmaking wastes other than from stainless steelmaking. Significantly, the ease of technology transfer has been demonstrated by a number of industrial-sized (19-ton) commercial electric furnace heats, in which the pelletized wastes represented some 10 to 20 pct of the furnace charge, replacing part of the normal scrap charge. Results of these successful large-scale trials are presented. Some information is also presented on incorporation into the pellets of chromium-bearing particulate wastes originating from other than steelmaking production. Cost evaluation indicates the process is economically attractive.

Jan 1, 1982

By Wilbert J. Huff

The organization of the Explosives Division has been outlined in two preceding publications., The activities of the various units for the fiscal year 1939 are described hereafter: I. INFLAMMABILITY OF GASES AND VAPORS DETERMINATION OF EXPLOSION HAZARDS OF COMBUSTIBLE GASES AND VAPORS IN MINES AND INDUSTRIES (a) Determination of Limits of Inflammability of Gases and Vapors The following hitherto unpublished limits of inflammability were determined during the past fiscal year.

Jan 1, 1939

By Wilbert J. Huff

The organization of the Explosives Division has been outlined in two preceding publications.3/ The activities of the various units for the fiscal year 1939 are described hereafter: I. INFLAMMABILITY OF GASES AND VAPORS DETERMINATION OF EXPLOSION HAZARDS OF COMBUSTIBLE GASES AND VAPORS IN MINES AND INDUSTRIES (a) Determination of Limits of Inflammability of Gases and Vapors The following hitherto unpublished limits of inflammability were determined during the past fiscal year.

Jan 1, 1939

The STATE MINERAL SUMMARIES publication provides estimated data and summaries of mineral activities at the State level for 1991. Most of the estimates are based on nine months data. Individual State summaries are published separately as State Mineral Industry Surveys and copies can be obtained from the appropriate State mineral officer or Bureau field office specified in each State summary.

Jan 1, 1992

By Jonathan S. Kelly

Effective control of respirable dust is one of the most serious problems associated with longwall mining in the United States. This report describes the development and the underground evaluation of ventilated cutting drums, on a double ended ranging drum shearer. The ventilated drum uses high pressure (1,500 psi) water sprays to draw air (3,500 cfm) through 12 airmoving tubes mounted in the drum hub. The sprays draw dusty air from the face side of the drum, scrub the air, and discharge the clean air on the gob side of the drum against a deflector plate. During a three week underground evaluation, the cutting drums reduced shearer generated dust levels at the shearer operators position by 40%, at the shield operators downwind of the shearer by 55%, and at the tailgate by 55%. Cutting and loading performance of the drums were superior to the mine?s conventional drums. After the evaluation, the mine continued to use the ventilated drums to finish mining the panel. During this 3 month period, there were no mechanical or seal failures demonstrating excellent system reliability.

Jan 1, 1987

By William R. Barton

Dimension stones, with their almost infinite variety, have a broad range of properties and uses. Natural stone was beyond doubt the first mineral commodity used by man. Today dimension stone has widened to encompass building exteriors and interiors, decorative and ornamental modes, statuary, monuments, paving, curbing, flagging, roofing, and miscellaneous categories such as blackboards, surface plates, and honestones. For many purposes, it competes with greater or less success with alternate materials such as concrete, metal, brick, plastic, or glass. The almost ubiquitous geographic distribution of stone resources is the basis for a dimension stone producer industry in almost every State and in almost every land. In the United States, alone, dimension stone sold or used by quarries is valued at 2 million to 3 million dollars annually. Mining, finishing, transportation, and use technology have been modernized, resulting in a broader spectrum of stone products and new adaptions in use. Increased efficiencies also have been reflected in costs and prices and, coupled with gains that should be realized from current research, auger well for continued vitality of the ancient and honorable dimension stone craft.

Jan 1, 1968

A major highlight of Fiscal Year 1993 is the completion of a new research facility dedicated to the advancement of robotics research and development. This new facility brings to the U.S. Bureau of Mines one of the largest and most unique facilities of its kind in the world. Located at the Bureau's Pittsburgh Research Center, the facility consolidates under one roof, all of the resource requirements of a first class automation and robotics research program. The Mining Robotics Development Center (MRDC) is the result of a major renovation of a large under-utilized warehouse-type structure and brings together the laboratories and offices previously housed in five separate buildings scattered throughout the Pittsburgh Research Center's 238-acre site. This new facility will support the computer-assisted mining research program, a high priority, multi-million dollar program that is expected to have a high impact on the health and safety of miners and coal productivity.

Jan 1, 1993

By John L. Ellenberger, Gabriel S. Esterhuizen

Observations of pillar conditions in limestone mines showed that the presence of weak bands in the limestone can result in pillar damage at stresses that are lower than one would otherwise expect. The objective of this National Institute for Occupational Safety and Health study was to investigate the mechanism of failure caused by the presence of weak bands by using a series of numerical models based on realistic physical properties. The effect of the weak bands on pillar strength was also investigated by developing a series of pillar models with different width-to-height ratios and determining their strength by simulating a servo-controlled loading condition. The material properties of the bands and the limestone were varied and their effects on pillar strength were determined. Model results demonstrated failure development similar to the pillars observed in the field. The weak bands were seen to develop tensile stresses in the limestone as they extrude under increasing stress. The limestone fails in tension at a much lower stress than its expected uniaxial compressive strength. The results showed the load bearing capacity of the pillars can be reduced significantly by the presence of multiple thin weak bands. The degree of strength reduction is largely dependent on the compressive strength, the frictional resistance and the thickness of the weak bands. Single weak bands do not affect pillars as severely as multiple bands. However, the model results show that a single thick weak band, which comprises more than about 2 percent of the pillar height, can cause a significant reduction in pillar strength. The weakening effect of the bands become less severe as the pillar width-to-height ratio is increased. Field observation of spalling and failure associated with weak bands in limestone pillars show that the failure mechanism in the models resembles the observed failure. The model results provide insight into the important factors affecting pillar strength in the presence of weak banded materials.

By J. Koster

In the western United States occurs deposits of low-grade chromite which, when concentrated, may be reduced to ferrochromiun in electric furnaces that derive energy from dams and hydro plants now in course of construction. Montana ore was chosen for the experiments. A 1-ton sample contained 26 percent Cr203, 17 percent Fed, and 17 percent SiO2, plus other constituents, and the concentrates therefrom assayed 44 -percent Cr203, 23 percent FeO, and 0,79 per cent SiO2, Gravity concentration was found to be the best method. Ferrochromiums are of two grades - high-carbon with 66 to 70 percent chromium and 4-112 to 6 percent carbon and low-carbor with 67 to 72 percent chromium and 0.6 to 2 percent carbon. Both are made in electric furnaces that use anthracite as a reducer and suit-able fluxes. The concentrates mentioned mere smelted under different conditions, and it was concluded that domestic ore could be reduced with anthracite to produce a ferrochromium of S to 10 percent carbon content at yields of 90 percent without re-treating the slag. This carbon may be lowered to required proportion with calcium and silicon, but the former requires a great excess and the latter leaves an alloy high in silicon. INTRODUCTION Chromite occurs in several regions of the United States, but the known deposits of this mineral have not been large enough or high grade enough to permit them to compete under normal conditions with imported ores. There are numerous deposits of chrome ore along the West coast. These are generally conceded to be relatively small, although some were worked during the World War. There are some indications of a revival of interest in California chromites. Montana contains large chromite deposits in Stillwater and Sweetgrass Counties. The utilization of chromite for ferrochromium and. the manufacture of stainless steels is distinctly an electrometallurgical problem; consequently, a study of methods for treatment of chromite might pave the way for the establishment of new electrometallurgical industries in the Western States. This thought is supported by the cheap power that is soon to become available from the western dams, Farther, submarginal domestic chrome deposits might thus be turned into profitable producers.

Jan 1, 1936

By J. Koster

In the western United States occurs deposits of low-grade chromite which, when concentrated, may be reduced to ferrochromiun in electric furnaces that derive energy from dams and hydro plants now in course of construction. Montana ore was chosen for the experiments. A 1-ton sample contained 26 percent Cr203, 17 percent Fed, and 17 percent SiO2, plus other constituents, and the concentrates therefrom assayed 44 -percent Cr203, 23 percent FeO, and 0.79 per cent SiO2, Gravity concentration was found to be the best method. Ferrochromiums are of two grades - high-carbon with 66 to 70 percent chromium and 4-112 to 6 percent carbon and low-carbor with 67 to 72 percent chromium and 0.6 to 2 percent carbon. Both are made in electric furnaces that use anthracite as a reducer and suit-able fluxes. The concentrates mentioned mere smelted under different conditions, and it was concluded that domestic ore could be reduced with anthracite to produce a ferrochromium of S to 10 percent carbon content at yields of 90 percent without retreating the slag. This carbon may be lowered to required proportion with calcium and silicon, but the former requires a great excess and the latter leaves an alloy high in silicon. INTRODUCTION Chromite occurs in several regions of the United States, but the known deposits of this mineral have not been large enough or high grade enough to permit them to compete under normal conditions with imported ores. There are numerous deposits of chrome ore along the West coast. These are generally conceded to be relatively small, although some -were worked during the World War. There are some indications of a revival of interest in California chromites. Montana contains large chromite deposits in Stillwater and Sweetgrass Counties. The utilization of chromite for ferrochromium and. the manufacture of stainless steels is distinctly an electrometallurgical problem; consequently, a study of methods for treatment of chromite might pave the way for the establishment of new electrometallurgical industries in the Western States. This thought is supported by the cheap power that is soon to become available from the western dams. Farther, submarginal domestic chrome deposits might thus be turned into profitable producers.

Jan 1, 1936

By David Bendersky

The principal objectives of this study are to: (1) survey electrical practices in metal and non-metal mines, (2) survey electrical practices in metal and non-metal mills, (3) clarify the federal regulations governing electrical practices in metal and non-metal mines/mills, (4) analyze electrical accidents, and (5) make recommendations aimed at improvement of the safety of electrical practices in metal and non-metal mines. Information was obtained from literature searches, accident reports, visits to 27 mines and 12 mills, and discussions with knowledgeable industry and government people. The various electrical power systems and practices at the mines and mills visited are described. Similarities and differences based on the type of mining and the minerals being mined or milled are presented. The federal regulations governing metal/non-metal mine/mill electrical practices (Code of Federal Regulations, Title 30, Sections 55.12, 56.12, and 57.12) are presented and discussed. Explanations of each regulation are provided in an appendix. The attitudes of mine/mill operators towards the federal regulations are described. An analysis of the electrical accidents in metal/non-metal mines and mills during the period 1972-1978 is presented. Recommendations, including specific research and development activities, aimed at improvement of electrical safety in metal/non-metal mines are submitted.

Jan 1, 1980