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In 1991, the USBM (U. S. Bureau of Mines) evaluated the mineral resources of the 174,550-acre Bear Creek-Poker Peak area. Located 40 air miles east from Idaho Falls, ID, the study area is in the Caribou National Forest but is mostly administered by Targhee National Forest. USBM personnel mapped and sampled mines, prospects, and mineralized sites in and near the study area. Five types of mineral occurrences were identified in the study area: phosphate, limestone and travertine, placer gold, coal and uranium (the latter contained in the coal), and oil and gas. The study area has a high potential for oil and gas; evaluation of these commodities were beyond the scope of this study.

Jan 1, 1992

By 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 A. Wahab Khair, S. Jung

"This paper deals with the fracturing process of laterally confined blocks of coal subjected to impact indentation. During the test, blocks of coal with approximate dimensions of 10 in. x 10 in. x 6 in. were laterally confined to predetermined equivalent in-situ stresses and then subjected to an impact indentation by dropping coal cutting bits (various shapes) attached to a known weight from a known height. During the test a number of parameters, namely surface strains (using strain gages), penetration depth (using L.V.D.T.) and acoustic emission characteristics were measured. After the test, the fractured surfaces were photographed with the aid of a camera attached to a microscope. The fracture, its intensity and extended zone within the coal blocks were mapped using sonic techniques. By correlating measured parameters, fractured zones under a given set of test parameters were identified and characterized.INTRODUCTION To improve the understanding of basic failure mechanisms in coal cutting, a better knowledge of fracture and crack regions caused by the indentation in coal is needed. This study reports the detailed experimental procedure used in fracture analysis of indentation experiments on coal specimens using the Acoustic Emission (A.E. hereafter) and sonic techniques. The relationship between microcracking and the inelastic deformation of rock was confirmed by a series of experiments in which the A. E. generated by the cracking in the rock specimen were recorded and the number of events were compared to the strain measurement. (Scholz, 1967).According to fracture mechanism theory, crack initiation in brittle materials such as rocks begins from ""flaws"" either pre-existing or induced by the indentation process itself. Rocks are pervaded by natural cracks and pores, from which numerous possibilities for crack initiation arise (Lindquist, Lai and Alm, 1984)."

Jan 1, 1989

By James A. Whelan

The Bureau of Mines sponsored research studies of variables in rotary drilling, done in the Department of Mineral Engineering, University of Minnesota. By studying carefully controlled drilling with good instrumentation, it was hoped to obtain a better understanding of rock failure during drilling and of the stresses in drill bits during drilling. Experimental procedures and equipment are described. From these studies it was concluded that 1. Thrust requirements, other things being equal, are proportional to the total length of cutting edge in the bit. 2. Data from penetrating a wedge into rock under thrust only are not directly applicable to rotary drilling. 3, In rotary drilling the initial wear on a bit greatly decreases penetration rate under any given set of conditions; however, after initial wear the effect of wear on penetration rate is reduced. 4. An increase in rotary speed increases the overall penetration rate but decreases the penetration per revolution. 5. An increase in thrust increases the overall penetration rate and the penetration per revolution. 6, Torque on a drill bit is proportional to both penetration rate and bit diameter. 7. For small-diameter holes full-hole drilling will save both drilling time and energy compared with pilot drilling followed by reaming; for large-diameter holes pilot drilling-reaming is advantageous in both respects,

Jan 1, 1962

By A. D. German

This paper presents one of a series of digests of foreign mining legis- lation and court decisions which is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of tie laws of Ecuador has been prepared from the best available information in Washington, but is released subject to correction and amplification, if necessary, by the proper American diplomatic and consular officers to whom it is being referred through the courtesy of the Department of State..

May 1, 1930

By Joseph W. Martin

The Bureau of Mines investigated the backscattering of low-energy gamma rays as a method for rapidly determining the incombustible content of coal mine dust. In this method, 60-kev gamma rays from americium-24l penetrate the dust and are reflected by elements in the dust to a thin crystal scintillation detector. The number of backscattered gamma rays is proportional to the incombustible content. Tests of 40 dry, mine-dust samples containing 50 to 100 percent inert material show an average error of 2 percent. Calibration of the apparatus is necessary for each rock dust to account for variable composition. Results for samples containing more than 6 percent moisture are subject to error, but the values are lower than values obtained by chemical analysis, and thus fall on the safe side. Development of a small portable meter based on the backscatter principle appears feasible. Such a meter would find application within coal mines to check the effectiveness of rock dusting procedures.

Jan 1, 1968

By G. S. Rice

This paper describes preliminary tests at the Bureau's Experimental Mine to determine, under conditions that may prevail in a bituminous coal-mine heading, how small a quantity of fire damp may bring coal-dust into suspension and ignite 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 explosive mixture, as at the face of an entry which was 10 feet wide and the face was overcut to a depth of 6 feet and an upper layer of coal 2.5 feet thick had been removed, the recess so made would have a volume of 150 cubic feet. Furthermore, only 13 cubic feet of pure methane is needed in thin volume to produce this 9 per cent explosive mixture.

Jan 1, 1930

By Fredrick L. Johnson

In 1984, at the request of the U.S. Forest Service, the U.5, Bureau of Mines began a study of the 94,370-acre Arc Dome study area (4-667) in order to appraise its mineral resources, The Bureau of Mines mapped and sampled mines, prospects, and mineralized sites in and near the area, The study area is located in the Toiyabe National Forest, about 54 mi north of Tonopah, Nye County, NV, It is estimated that over 500 claims have been staked in the study area since the mid-1800?s. In January 1986, there were 108 active mining claims completely inside and 59 on the boundary. Another 283 active claims were outside the study area but within 1 mi of the boundary, In addition to the large number of claims staked, exploration activity is also reflected by the almost 700 inactive workings that were found during field investigation.

Jan 1, 1989

By M. C. McCall

When electric current of any appreciable magnitude flows from a power line into the earth, a change sometimes takes place in the conditions of resistivity immediately surrounding the electrode or medium of contact. If the conducting medium is composed of moist earth or clay the effect is to increase rapidly the resistance. If the conducting medium is coal or a coal bed, the effect is one of slowly decreasing resistance as the coal is carbonized, If, however, the flow of current is not enough to carbonize the coal, it will dry slowly, with a resultant increase in resistance. Measuring ground resistance, or impedance, with conventional commercial ground testers does not always indicate the current that will flow in the earth circuit from a direct-current or an alternating-current power circuit. The exact reason for this has not been determined however, it is thought to be due to the comparatively minute currents used for such testing. A typical ground, tester used by the authors for this work indicated a maximum current of 25 milli-amperes. The frequency of this testing current also has an effect on the readings in all probability. While the possibilities of the effects of varying frequencies has by no means been fully explored in this investigation, there are very definite indications that the impedance of a circuit through a section of earth will vary in some inverse relationship to the frequency of the applied voltages. This is evident at ordinary power-line frequencies ns well as at higher frequencies up to 200 kilocycles, which was the highest frequency available for tests in this investigation. This report is written in the hope that it will stimulate further investigation of the possibilities suggested for communication and the development of safety devices for increased electrical safety in coal mining.

Jan 1, 1952

By H. R. Beard

The citrate process for sulfur dioxide emission control was developed in pursuit of the Bureau of Mines goal of minimizing the adverse environmental impact of mineral-processing operations. This publication describes the gas analysis procedures used during development of the process. The research required the capability to analyze SO2, H2S, CO, CO2, COS, volatile hydrocarbons, NO, NO2, O2, N2, and H2. The methods described include gas chromatography, electrochemical detection, infrared spectroscopy, and the use of a computer program to predict the product composition in complex reactions. Laboratory and pilot plant applications are discussed.

Jan 1, 1979

By H. D. Jacobs

The Bureau of Mines undertook a research program to insure an adequate supply of iron raw materials for future iron and steel making needs. A sample was obtained of oxidized taconite from the western Mesabi Range in Minnesota, and the metallurgical response of the taconite to beneficiation by a process that included selective flocculation-desliming-cationic flotation was evaluated. The sample contained 35.3 pct iron and represented approximately 2 billion tons of crude material. Selective flocculation and flotation were evaluated in a pilot plant with a feed rate of 900 Ib/hr. Concentrates averaging 61.7 pet iron and 5.1 pet silica were obtained, with an accompanying iron recovery of 67.2 pet. About 83 pct of the process water requirements were reclaimed from the slime and froth tailing and then recycled.

Jan 1, 1980

By H. Kenworthy

A zinc-pyrite ore from the Gray deposit in Jo Daviess County, Ill., was successfully concentrated on a laboratory scale. Initially, drill cuttings were submitted for separation of zinc and iron concentrates. Subsequent to mine development, a large sample of coarse ore was submitted to ascertain its amenability to sink-float treatment to produce a low-grade zinc-iron concentrate and discard a clean tailing. The samples of ore were submitted to the Rolla Metallurgical Branch by the Mining Division of the Federal-Bureau-of Mines. They were obtained during the recent war as a part of the extensive government program to increase metal production through exploration for new mineral deposits and investigation of old mineralized areas. The first sample consisted of about 3,000 pounds of drill cuttings collected, during the Bureau?s churn and diamond- drilling program. The second sample was taken at a later date, after Tri-State Zinc, Inc., had opened the deposit and commenced milling the ore. This sample consisted of a ?ton-of mill feed crushed through 2 inches and collected over a period of 3 days.

Jan 1, 1949

By D. R. Tesarik, M. K. Larson, D. K. Denton, J. B. Seymour, R. L. Rains, T. J. Williams

Because backfill has occasionally collapsed into an active working area, posing a hazard to miners, engineers from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health and Hecla Mining Co. installed instruments in a cemented, backfilled, stope-ramp intersection at Hecla’s Lucky Friday Mine, Mullan, ID. The purpose was to measure stress and strain changes in the backfill and reinforcing members during undercut mining. The instruments were monitored for 6 months while three successive cuts were mined below the intersection. Readings showed induced loads up to 3450 kPa (500 psi) in the backfill as stope walls converged 2.5 to 12 cm (1 to 5 in). The backfill then deformed against the top and bottom plates of the 2-m- (6-ft-) long vertical rock bolts installed as reinforcement, producing loads to 177 kN (40,000 lb)on the rock bolts. We hypothesize that a compressive zone was created in the backfill that allowed the backfill to remain stable as long as the compressive zones from adjacent rock bolts overlapped. This hypothesis is presented in graphical form. Of particular interest was the effect of loading on trusses installed to augment the vertical rock bolts and wire mesh typically installed in backfill. Data from the instruments indicate that wall closure perpendicular to the vein induced loads in truss legs parallel to the vein and in the rock bolt driven through the center of the truss, but, because they are designed to function under tension, truss legs perpendicular to the vein supplied in significant support as a result of compressional forces from wall closure. Based on this study, use of trusses was discontinued, and an alternative support system of wood beams and posts was installed as needed to ensure the safety of miners working beneath the backfill in stope-ramp intersections.

Jan 7, 2001

By J. D. Zetterstrom

This report supplements an earlier publication on lightweight aggregates of North and South Dakota.3/ The purpose of the investigation was (1) to study the expansion characteristics of large samples of Dakota clays and shales in a 12-inch by 15-foot rotary kiln; and (2) to improve the laboratory bloating test as a tool for predicting the suitability of samples for the rotary-kiln process. This was done by comparing results of the laboratory and kiln tests.

Jan 1, 1956

By James E. Mauser

This report deals with the investigation of a continuous process for producing pure zirconium. It covers the construction, operation, and maintenance of the semicontinuous reactor. The report covers a study of test variables, such as reactor temperature and reluctant charge weights, and evaluates the results, such as billet metal hardness, residual billet salt content, and suitability of a purified billet as a consumable electrode for arc melting. The purpose of this project was to develop an inexpensive and continuous process for producing pure zirconium. The process developed, termed the semicontinuous reactor process, produced billets of compacted zirconium sponge. The metal was produced by reducing zirconium tetrachloride with sodium and magnesium beneath molten byproduct salt. Hydraulic rams at each end of a vertical reaction tube compacted the sponge and ejected it as a billet. These billets were purified by heat under vacuum to remove entrapped salt. The goal was to utilize the purified billet directly as a consumable electrode for arc melting.

Jan 1, 1961

By L. A. Haas

The U.S. Department of the Interior, Bureau of Mines, is conducting laboratory-scale research to determine the leaching conditions required with sulfuric acid for extracting base metal from a matte with a copper-to-nicke1 ratio of 6 to 1. The matte (61.2 pct Cu, 9.7 pct Ni, 3.3 pct Fe, 21 pct S, and about 5 oz of precious metals per ton) was prepared from Duluth Complex (Minnesota) ore by smelting a bulk sulfide flotation concentrate. The matte was pre leached at atmospheric pressure to selectively extract 20 pct of the nickel, and the undissolved solids were referred to as the matte residue. Autoclave leaching of the matte residue extracted over 95 pct of the nickel, copper, and iron. The remaining leach residue in the autoclave contained over 100 oz of precious metals per ton. The leaching conditions required were matte grind of greater than 98 pct minus 325 mesh, pulp concentration of 50 g/1, total pressure of 100 psig with oxygen at 150° C or 400 psig with air at 180° C, 50 g/1 H2S04, 700 rpm agitator speed, and 6 hours of leaching time. The leaching time was decreased to 2 hours by increasing the agitator speed to 1,300 rpm. Sulfuric acid concentration greater than 50 g/1 did not appreciably enhance the base metal extraction, but with less acid, residues with higher iron concentrations were obtained. Supersaturation of the liquor was prevented at 150° C by using a 1ixiviant that contained 30 g/l Ni and 20 g/1 Cu.

Jan 1, 1979

By E. A. Magill

The Bureau of Mines has begun a study of the copper resources of the Cascade Mountains of Washington. The program includes reconnaissance of mineralized areas and examination and occasionally limited exploration of deposits that are considered characteristic of an area. The Bureau of Mines believes that published information may assist industry in searching for new sources of copper. The Miners Queen is one of a few Cascade Mountain deposits selected for prelim¬inary exploration. The investigation was not planned to delineate the ore body. A diamond-drilling program was carried out at the Miners Queen mine in the summer of 1955. Five diamond-drill holes were completed, totaling 628 feet. Two 35-foot shafts were dewatered, and all accessible underground and surface workings were examined.

Jan 1, 1957

Under the Bureau of Mines Research Contract Number H0252071, Foundation Sciences, Inc. has compared the relative effectiveness of roof bolts installed at an angle over the rib with that of bolts installed vertically at the rib side, The information gathered during this investigation was sufficient to supply supplementary information on the mechanics of roof support systems and the general acceptability of field instrumentation methods. During the 140 days of field investigation, 235 bolts were installed, 45 inclined and 190 vertical, in two adjacent intersections. Of these 235 bolts, 30 were in-stalled with load cells and 38 were tested for anchor capabilities. In addition to this instrumentation, the deformation of the opening was measured by convergence meter on 9 lines throughout the two testing areas, and a borescope and photo-elastic gauges were utilized to obtain information on the roof action beyond the surface.

Jan 1, 1977

By F. E. Diebold

The methodology for describing the geochemistry of elements in a coal seam have been developed. This has been applied to the Rosebud Coal Seam, which is an economically important member of the subbituminous coals of the Fort Union Formation in Eastern Montana. The method development has involved a detailed study of two popular techniques for determining the metal geochemistry of coal, namely, whole coal analyses and coal physical fractionation. The mathematically contrived element associations (whole coal analyses technique) and the element concentration trends in the float and sink fractions (physical fractionation technique) are considered to lead to only qualitative conclusions concerning the chemical associations of the elements in coals. Additionally, the processes taking place with the coal during low temperature ashing in an oxygen plasma are experimentally investigated and shown to be of sufficeint extent that the use of such low temperature ash for deciphering element geochemistry is questionable. The method developed in this study is a chemical fractionation that involves the sequential leaching of coal with water, 0.5 N HC1, 3 N HC1, 2 N HNO3, and 48% HF. These leach solutions are shown to selectively dissolve the predominate inorganic phases, sulfates, Ca and Mg carbonates, Fe sulfides and K alumino-silicates and quartz, respectively. These phases were identified with the use of XRD, SEM, EM and leaches (water and 0.3 N HC1) of whole coal and low temperature ash. The incorporation of the anion-exchange step in the leaching scheme was investigated and was observed to warrant further study of such intensity to be, at the time, unuseable. The use of this sequential leaching technique on several coal samples from the same seam generates element concentration trends that can be quantitatively interpreted with respect to the chemical associations of the minor and trace metals in the coal seam. The properties of the various seams of economic importance in the Fort Union Formation in Eastern Montana are compiled and presented. The subsequent conclusion is that there is not a large variation in the properties of these coal seams and that the variations within the Rosebud are within one order of magnitude. The chemical fractionation technique, investigated in this study, was applied to composite tipple samples of the Rosebud seam. Each composite sample represented 76,800 tons of coal. A minimum of 32% of the Ca and Mg are present as separate water soluble sulfates. An excess of the sulfate ion in the water extracts shows the predominating influence of the ion exchange capacity of the organic compounds in the coal. Based upon the CO content of the coal and the HC1 leachate data, 25 to 30% of the alkaline earth elements exist as separate carbonates and the remainder are associated with the organic compounds. The small fraction of the illite that dissolves in the HC1 and HNO3 leachates accounts for the K and Al. Slight dissolution of the pyrite in the HCl solvent occurs, the small amounts of Li and As do not relate to any known phase and Mn is present as a separate carbonate phase. Fe and a significant amount of the As exist in the pyrite that is dissolved in the HNO. Se is equally partitioned between the pyrite and the organic compound~. Most of the trace elements are found in the HF solutions. Li, V, and Cr were interpreted to be associated with the clay minerals (kaolinite and illite). Ni and Pb appear to be present as separate phases and 50% of the Hg is HF soluble but is not chemically related to any known inorganic phase.

Jan 1, 1983

By Jon C. Volkwein

Advances in mining technology have enabled deeper seams of coal to be mined from the surface. Highwall mining is frequently used to mine areas at the perimeters of a surface mine when removal of the overburden becomes uneconomical or threatens environmentally sensitive surface features. At the same time, advances in materials and technology have enabled highwall mining of coal that create blind headings over 300 meters in length. Deeper surface mining and deeper highwall penetration depths have lead to more frequent encounters with methane gas. While this coal is remotely mined from the surface, underground ignitions of methane have propagated to the surface and injured miners. Methods described in this paper show how this hazard can be correctly monitored and controlled for auger type highwall mining machines. Research indicates that small quantities of gas liberated during mining migrate to the face, creating higher gas concentrations than would otherwise be expected. Using the same principles that cause the gas to migrate to the face, researchers have shown that inert gas introduced at the collar of the hole can inert the entire hole, thus ensuring safe conditions for mining.