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By Christopher Mark, Gregory M. Molinda, Timothy M. Barton

The Coal Mine Roof Rating (CMRR) was first presented at this Conference nine years ago. Since its introduction, the CMRR has been incorporated into many aspects of mine planning, including longwall pillar design, roof support selection, feasibility studies, and extended cut evaluation. It has also become truly international, with involvement in mine designs and funded research projects in South Africa, Canada, and Australia. The purpose of this paper is to bring the mining community up to date with recent improvements and applications of the CMRR. The most important new development is a streamlined process for determining the CMRR from exploratory drill core. Just three types of information are now required: •Fracture spacing (or RQD) •Uniaxial compressive strength (or axial Point Load Testing) •Diametral Point Load Testing The moisture sensitivity adjustment has also been changed, and new research has related the immersion test to slake durability. Most recently, the CMRR has been implemented in a computer program, which can be obtained from NIOSH free of charge. The program facilitates calculation of the CMRR from either underground or drill core data. Values from many locations can be saved in a single file, and an interface with Autocad allows CMRR contour plots to be integrated into mine planning.

By Joseph M. Kurtak

The U.S Bureau of Mines conducted a five-year mineral resource assessment of the 16.6 million acre Colville Mining District in northern Alaska, which includes part of the National Petroleum Reserve in Alaska. The study was initiated at the request of the Bureau of Land Management, which administers the majority of the region. The study was done in cooperation with the Alaskan Division of Geological and Geophysical Surveys, the U. S. Geological Survey, and the University of Alaska. During fieldwork, 1593 rock, soil, and stream sediment samples were collected and four bulk samples taken for beneficiation studies. A total of 40 mineral occurrences were documented, including 27 which were previously undescribed. No mining has occurred within the district. Mississippian carbonaceous shale and siliceous mudstone contain stratiform exhalative lead-zinc-silver occurrences. Grades average 8.0% combined lead/zinc and 51 gm/mt silver. Upper Devonian to Lower Mississippian sandstones host breccia veins, containing up to 29% combined lead/zinc and 274 gm/mt silver. Mineralized quartzites of similar age have potential for disseminated-type lead-zinc deposits. Samples from Lower Cretaceous mudstone and shale beds up to 6.5 meters thick, contain as much up to 12% manganese. Upper Mississippian carbonaceous shale and limestone beds contain up to 23% phosphate. Stratiform barite deposits hosted by cherts, are up to 27 meters thick with an average specific gravity of 4.16. Vein-type fluorite occurrences are associated with Mississippian limestone. Moderate potential exists for development of zinc -lead-silver, barite, and phosphate deposits.

Jan 1, 2011

By S. Gallagher, C. A. Hamrick, A. G. Mayton, R Sonier, R. L. Unger

Introduction Industrial safety professionals recognize that adequate illumination is essential to a safe and productive work environment. The need for effective, lighting in underground coal mines is even greater.1 Designing appropriate lighting systems for these mines is no easy [ ] task because of the unique environment and work procedures encountered in underground coal-mining operations. Miners must depend totally on artificial lighting systems to see. Moreover, the working face is a low-reflectivity and low-contrast environment and is continually advancing or retreating.2 Laboratory mock-ups have been a major part of the process lighting equipment manufacturers must under- go to design an underground machine-mounted lighting system. The mock-ups often have taken considerable time. Furthermore, modifications to a lighting system (using different luminaires with an existing configuration or changing a luminaire's location, orientation, etc.) could require more time with additional mock-ups and laboratory measurements. Understanding the need to improve this situation, the US Bureau of Mines has developed an alternate method for facilitating lighting system mock-ups. A PC-Program (CAP),* with the latest software technology enables users to design, alter, and evaluate under- ground machine-mounted illumination systems. Lux levels and distance are measured as the luminaire is moved incrementally through angular traverses about horizontal and vertical axes. The measurements and angles subsequently are entered into the model. From this input data, three-dimensional isolux or isofootcandle profiles are constructed for luminaires that can be placed at various locations and orientations on a mining machine. As an example, Figure 1 shows a computer display of 21.5 Ix or 2.00 fc profiles for luminaires mounted on a simulated mine-shuttle car. Using this information, the model allows the user to determine the lux level at different locations in space about the shuttle car. How the model calculates illumination During initial development of the CAP model, the isolux profile of the luminaire was determined using the inverse square law (ISL) .3 The method of gathering data comprised recording a single measurement of distance at 21.5 ± 1.21x (2.00 ±11 fc) for angular traverses following 0.09 rad (5 degree) increments. This data was then used to find the illumination in space for any other distance at a given azimuth and elevation using the ISL. Limitations, however, exist with this method.4 The main one is that the ISL assumes a luminaire is a single point source of light, so long as the distance is greater than five times the 1al;gest dimension of the luminous area of the luminaire.5 Also, by using a single measurement to calculate the illumination for a given luminaire in the CAP model a large error could result from an inaccurate measurement.

By C. L. Brown

Among the more recent developments for breaking coal in mines is the Airdox system, in which high-pressure compressed air is conducted to the points of application by means of heavy-duty steel and copper tubing. Stray electric currents can be detected on y of the compressed-air lines, and evidence of such currents is rev led, by arcs and sparks when contact is made between the tubing and mine track or other equipment forming a current path with the track. Explosive gas is liberated in many coal mines; therefore, from the standpoint of safety, it is desirable to eliminate all possible sources of gas ignition, including stray electric currents. The purpose of this report is to reveal the source, magnitude, and possible methods of controlling stray currents in compressed-air lines that are used in connection with Airdox systems. Stray electric currents have been studied in most coal-mining localities in the United. States where Airdox equipment is used. The information given in this report is based on the find of these studies.

Jan 1, 1949

By G. L. Oldright

The first Report of Investigations of the present series (No. 4562) was on the fundamental properties of lead compounds, and the manner in which they set limits to the richness of lead products treated in the usual sintering-blast furnace units. These properties of the compounds were emphasized, as' it was desired, also, to learn the limitations of smelting the same compounds in present ore hearth practice; the hearth has a competitor in these "usual" units, even with the rich lead feeds best adapted for the hearths. Operating conditions that were followed in older metallurgical processes, when rich products, were treated, were outlined. The second report of the series (R. I. 4563) was on the development of the ore hearths of the types now used in the Tri-State from the viewpoint of the features, functions, and dimensions of the earlier hearths that had been most changed. Experimental data, for both well and poorly desulfurized charges being considered, were given to show the relative changes in the sizes and compositions of the charges after they were added to the ore (Scotch) hearths. A general picture was given of the charge column and of the conditions prevailing there when the operation was satisfactory. In this third paper, the composition of the gases prevailing in the charge column at various elevations will be correlated with what has been learned of the nature of the charge column in order to trace the steps of operation by which lead sulfide is converted into metallic lead. The metallurgical factors that govern operation and the lines along which improvements may be made will be noted.

Jan 1, 1949

By W. W. Adams

The first full year of the second World War for the United States presented a picture of the metal-and nonmetal-mining 4 industry which, without proper analysis and explanation, would convey a distorted view of achievements during 1942, especially because employment at gold and silver (lode and placer) mines-the largest group-declined to such an extent that the over-all totals for the country were reduced even though increases were made at mines producing copper, lead-zinc, iron, miscellaneous metals, and non-metals. A complete panorama of the metal-and nonmetal-mining industry, exclusive of coal mining, reveals a decrease in the number of men employed, the man-hours of employment, and the accident-frequency rates. Were the gold and silver (lode and placer) mines to be considered as a separate category; it would be seen that the number of men employed at all the other groups of mines increased appreciably over 1941. These other increases must be considered important, since these mines produced the vital war minerals that made valuable contributions to the military successes of the United States and its Allies during the year. A separate analysis of each of the various groups of mines may be found elsewhere in this bulletin. For the purpose of maintaining continuity in this series of bulletins, however, the discussion in this introduction will be confined to the entire metal-and nonmetal-mining industry (excluding coal mining, for which a separate bulletin, No. 462, has been published).

Jan 1, 1945

By S. L. McGill

The U.S. Bureau of Mines has determined the microwave heating rates for a suite of minerals and reagent-grade compounds. Maximum temperature achieved for the samples and the time required to reach temperature are reported. Heating rates of powdered samples are presented as a function of incident powers up to 3,000 W at 2,450 MHz. Descriptions of the microwave cavities, test cells, and a thermocouple assembly used to measure temperature in the microwave field are given. Many minerals of value heated in the microwave field, whereas host rock or gangue materials did not. In general, heating rates increased as incident power was increased. Exceptions to this were some very good (CuO, Fe304, and PbS) and very poor (CaC03 and SiO2) microwave-absorbing materials that showed negligible changes with increased power. Applications demonstrating the use of microwave energy in mineral processing that are described herewith include oxidation-reduction reactions, mineral liberation, and mercury retorting-vaporization. Microwave data on mineral heating rates will provide insight to possible chemical and mineral processing applications as well as assist in predictions of processing parameters.

Jan 1, 2010

By H. D. Hess

This report presents the results of laboratory mineral evaluations conducted by the federal Bureau of Mines under the joint sponsorship of the U.S. Atomic Energy Commission (AEC) and the Bureau a! Ships, U. S. Department of the Navy. The major purpose of this investigation was to examine and evaluate zirconium minerals representing sizeable deposits in an effort to locate com¬mercial sources of high-hafnium ores. Although determination of the hafnium content was the principal objective, each of the zirconium minerals also was analyzed for combined zirconium-hafnium oxide, silica, uranium, thorium, yttrium, and cerium. The general laboratory procedure involved microscopic examination of the test samples, concentration of the hafnium-bearing zirconium mineral by standard laboratory techniques, and analysis of the derived concentrate by quantitative microscopic, chemical, and X-ray spectrographic methods. Of the several hundred samples tested under this program, 147 are discussed in this report, including 94 from domestic occurrences and 53 from widespread foreign sources.

Jan 1, 1962

By K. L. Erickson, Gerald A. Munson

"The need for spodumene as a source of lithia for war purposes led to the exploitation of the Edison pegmatite deposit 1-1/2 miles southeast of Keystone, S. Dak. The operation was conducted during 1943 and 1944 by the Lor Mining Co., Rapid City, S. Dak. Spodumene concentrates in the ratio of 15:1 were recovered by hand picking from a sorting belt. This method was expensive and wasteful of spodumene, owing to the small size of the crystals.Data4/ obtained by the Bureau of Mines indicates that blunging with hydroflouric acid or sodium hydroxide is a prerequisite to selective flotation. Results of tests by Denver Equipment Co., Denver, Colo., indicate that economic recoveries can be obtained in an alkaline circuit after desliming.At the request of the Lor Mining Co., K. L. Erickson, metallurgical engineer, was permitted to work in the pegmatite research laboratory to verify previous investigations and to determine problems that might be involved in commercial milling. The ensuing investigation indicated that electrolytes in the mill water produced a profound inhibiting action on the flotation of Edison spodumone.An investigation of mill water from various sources showed that some waters are suitable for the process and others are not. Subsequent testing showed that all of the available waters are suitable after treatment. The flotation of the Edison spodumene in an alkaline circuit after desliming and using oleic acid as collector is efficient and economical when the water does not contain impurities.In its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B.Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches arc under the supervision of Dr. R. S. Dean, assistant director.As the work was of a practical nature, samples from possible mill-water sources in the southern Black Hills were obtained, and commercial softening and demineralizing methods were investigated. Data on various waters tested are given in table 1."

Jun 1, 1946

By A. C. Johnson, McHenry Mosier

The Bureau of Mines has adapted its activities to needs of national defense and to conditions brought about by the war program . Its work is now oriented solely to war problems . After studying about 1,600 deposits of war minerals , exploration projects have been undertaken on 96 of the most promising , of which 56 have proved successful . These have indicated that 56 million tons of ore of commercial or near -commercial grade can be utilized to meet war requirements . Included in this amount are 1 million tons of tungsten ore ; 4 million tons of chromite ore, 10 million tons of manganese ore , 2 million tons of antimony ore , 1 million tons of mercury cre , and 28 million tons of iron ore . Work done in connection with exploration projects included 172,000 feet of surface trenching , 210,000 feet of drilling , and 21,000 feet of shaft sinking . Nearly 100,000 samples were taken, on which 500,000 analyses were made . Extensive metallurgical tests were made on ore from many of these deposits , both in the laboratory and in pilot plants , in connection with research to develop metallurgical processes for their treatment .

Jan 1, 1943

1.0 SCOPE AND REGULATIONS 1.1 This specification covers the minimum requirements for material handling and associated equipment including design and materials. 1.2 This specification requires compliance with all federal, state, local laws and regulations which may be applicable including the Occupational Safety and Health Act, Construction Safety Act as well as rules, regulations and standards of the Secretary of Labor.

Jan 1, 1979

By N. L. Wimmler

"INTRODUCTION The Southern Cross district in Deer Lodge County, Mont., has been chiefly a gold producer. Most of the production has come from gold-bearing hematite-limonite ores. Some of these ores were mined and shipped to smelters for use as flux in smelting copper ores. A magnetite deposit in the Pomeroy property, containing no gold or other economic nonferrous minerals, was mined from 1921 to 1923, the ore being shipped to smelters for flux.The iron-bearing deposits in the Southern Cross area were examined by Bureau of Nines engineers/ on June 28, 1943, and October 14, 1943. As a result, a Bureau exploration project was recommended; it was conducted during 1944. A magnetometer survey was first made of the magnetite-bearing area at and in the vicinity of the Pomeroy property. Exploration by diamond core drilling was then conducted within this area, and in the Southern Cross and Hold Fast properties. The cyanide tailings dump at the Hold Fast mill was sampled by auger drilling.This report presents the data obtained by the Bureau of Mines exploration."

Dec 1, 1946

By Vernon C. Davis

In initial attempts to mine taconite by conventional open-pit methods, the material tended to break into tabular blocks that were too large to be handled by conventional shovel dippers and were unsatisfactory in an ordinary crusher feed. A great amount of secondary blasting was necessary, which added considerably to the cost of mining. The Bureau of Mines and others are engaged in studies designed to contribute to the solution of taconite-mining problems. These studies concern problems related to drilling techniques and patterns, types and methods of use of explosives, and other factors relative to effecting maximum fragmentation at minimum cost. This report, is concerned with study of the application of shaped charges in drill holes, the effectiveness of shaped charges as compared to capped charges in secondary blasting, and the merits of different drilling patterns and methods of detonation of conventional-explosive charges. Fragmentation of taconite at or near the surface is controlled or strongly influenced by joint and bedding planes. Since all tests in this study were made in a jointed and bedded area, a definite conclusion as to the relative effect of a shaped charge in a drill hole, as compared to a conventional charge at greater depths and tighter ground, is precluded. However, application of shaped charges in primary blasting of taconite appears to be of no advantage. In secondary blasting of taconite, conventional, capped charges produced better breakage than shaped charges of the designs tested. Based on the results of conventional blasting practice in horizontal-, inclined-, and vertical-hole tests, no better fragmentation is obtained from blasting either horizontal or inclined holes, compared to vertical holes. Holes drilled in staggered parallel rows that intersect both series of joint planes at the greatest possible angle, give maximum breakage compared to rows paral-lel to one of the series of joint planes. Methods of detonation made little difference in breakage; but the milli-delay caps produced the best conditions for moving the broken rocks.

Jan 1, 1953

By C. H. Riggs, Kenneth H. Johnston

The application of modern secondary-recovery methods has made possible the the extraction of more than 13 million barrels of crude petroleum from the eastern part of the Delaware-Childers field Nowata County, Okla., over and above the production that might have :been expected by continuing primary production methods, including the use of vacuum. Foremost among the secondary-recovery methods used in this foil was the repressuring of the Bartlesville sand with air and gas through injection wells spaced on sym-metrical patterns. Between 1925 and 1945, about 51 billion cubic feet of air and gas were injected into the producing formation, and the total recovery was increased from, 25 million to about 40 million barrels of oil. To produce as much as possible of the 28 million barrels of recoverable oil remaining in the sand will require the initiation of systematic water-flooding projects on many properties and the continuation of air and gas injection on others.

Dec 1, 1946

Argentina follows Venezuela and Mexico as the largest producers of crude petroleum and natural gas in Latin America. Argentina 1S practically self-sufficient in fuels, but relies substantially on imports for its supply of copper, iron ore, ferroalloys, sulfur, and fertilizers. Mining activity is limited and is in an incipient stage of growth, considering the country's potential for mining. Most nonfuel mineral output in 1979 consisted primarily of minerals used for construction, while only 9% are other nonmetallic, and 2% are metallic minerals. Argentina is Latin America's major producer of boron minerals and uranium (yellow cake). Mineral exports consist primarily of borates, uranium concentrates, and of late, some tin. These exports have in the past been shipped mostly to Great Britain. London banks have been involved in arranging financing for St. Joe Minerals Corp. IS planned development of the El Pachon copper deposit (see map), and were being counted upon to also back the development of large copper and manganese projects. The following is a review of Argentine mineral production in 1979: (For 1981, the production of boron minerals is put at 167,000 metric tons and uranium at 300,000 metric tons.)

Jan 1, 1982

By Alex U. Miller

Since its beginning, the occupation of coal mining has been considered hazardous. It is true that there are hazards inherent in mining, but it is believed that most of them, at least, can be guarded against. Moreover, many man-made hazards can be eliminated by officials and workers adopting safer practices. Notwithstanding the hazards in coal mining, the fatal accident rate in the United States has improved. During the, period from 1911, to 1941, inclusive, the fatal accident rate varied from 5.35 to 2.22 per million tons of coal. With many handicaps during the war period, 1942-45, such as the lack of experienced manpower. and the, employment of untrained men, the increased average age of workers, and the shortage of equipment and supplies, the industry s ill further reduced its accident rate, so that it ranged from 2.30 to 1.724/ deaths per millon tons of coal. During 1944, 684,000,000 tons of coal was produced with a rate of 1.91, and during 1945, 631,000,000 tons was produced with a rate of 1.724/ deaths per millon tons of coal. The accident rate for 1945 was the lowest for the industry since records have been compiled.

Jan 1, 1946

By I. Iwasaki

In recent years the rapid depletion of high-grade iron ores and the demand by blast furnace operators for increasingly low-silica ores have stimulated interest in flotation studies of low-grade iron ores, such as wash-ore tailings and oxidized taconites. Four processes have been reported for the flotation separation of these iron ores--anionic and cationic collection of the iron oxides, cationic collection of siliceous gangue, and anionic collection of activated siliceous gangue (5).5/ The effectiveness of any one method, however, depends largely on the mineralogical composition and on the physical structure of the sample; hence, a comprehensive study of the floatability of the individual minerals occurring in these materials is essential. A review of the literature shows that the floatability of hematite and magnetite has been frequently investigated, whereas very little corresponding information is available for goethite, or for its more earthy form, limonite, both of which are abundant in the Mesabi and Cuyuna ores (19). The purpose of this investigation was to formulate general information on the floatability of goethite. Vacuum flotation, contact angle measurement, and simplified flotation tests using a modified Hallimond tube were used. The experimental results were correlated with the electrokinetic properties of goethite as determined by streaming potential measurement. The results were used to interpret the batch flotation tests made on an artificial mixture of quartz and goethite.

Jan 1, 1960

By D. Randolph Berry

Foster-Miller Associates has developed a set of guidelines to permit hoist manufacturers, mine owners, and MESA mine inspectors to design, purchase, install or inspect a safe and effective Emergency Escape Hoist, as required by the Coal Mine Health and Safety act of 1969. A series of surveys were carried out to determine: 1. The attitudes and local needs of the MESA District Managers. 2. Current escape hoist installations. 3. Equipment available for future designs. 4. Foreign methods and equipment for mine rescue. From these survey studies, preliminary guideline objectives were developed.

Jan 1, 2012

By J. Ritchey

This report describes the engineering feasibility and economic advantages of using a mobile bridge-type cross-pit belt conveyor system in conjunction with a large dragline to excavate and transport spoils in a typical Western surface coal mine. The studies show that such a system could be built to survive operational and climatic mining conditions, and that its implementation would offer a reduction in both acquisition and operating costs versus conventional mining units of comparable rapacity. Reclamation costs can also be significantly reduced, and the total reclamation process accelerated, making the cross-pit conveyor system attractive to mine Owners and environmentalists alike.

Jan 1, 1976

By Xintan Chang

MFIRE is a computer simulation program that performs normal ventilation network planning calculations and dynamic transient-state simulation of ventilation networks under a variety of conditions. The program is useful for the analysis of ventilation networks under the influence of natural ventilation, fans, fires, or any combination of these. MFIRE simulates a mine's ventilation system and its response to altered ventilation parameters such as the development of new mine workings or changes in ventilation control structures, external influences (varying outside temperatures), and internal influences (fires). Extensive output enables detailed, quantitative analysis of the effects that the alteration will cause to the ventilation system. The program was developed at Michigan Technological University (MTU), Houghton, MI, with support from the Bureau of Mines. A personal computer (PC) version of the program was completed under contract for the Bureau by MTU. The purpose of this report is to document the installation and use of the PC version of the program MFIRE.

Jan 1, 1990