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By G. W. Jones

In a previous report'/ results were given and a method outlined whereby from a knowledge of the composition of the natural gas and of the inflammability limits of the individual constituents composing the natural gas, the limits of inflammability of natural gas and air mixtures could be closely calculated. This method is based on the application of Le Chatelier's law as modified by Coward, Carpenter and Payman,5/ to apply to a mixture of any number of combustible gases. This law must not be used indiscriminately, because many exceptions have been found. For example, when ethylene, acetylene, hydrogen sulphide, or chlorinated hydrocarbons are present the law may not hold. For a discussion of the many exceptions which have been found, reference should be made to a report by Coward and Jones.6/

Jan 1, 1933

By H. Miller

In recognition of the need for a portable low-profile hard rock crusher, the Bureau of Mines sponsored the development of such a unit capable of moving up as the face advances. By allowing primary ore reduction at or near the mine face, the advantages of conveyor haulage From the face as demonstrated in soft ore and coal mines, could be realized for hard rock Brines as well. This report presents the results of a development and testing program for such a portable low-profile crusher, designed by Eagle Crusher Company and called the M44. The unit has an extremely low vertical profile considering its size and capacity. The crushing jaws, which form the crushing lumber, are inclined, with the lower jaw mounted for eccentric movement relative to the stationary upper jaw. This provides efficient crushing while also forcing material through the crushing chamber. As a result, the inlet feeder can be disposed horizontally. To facilitate correct processing of different materials, the size of the discharge opening and the action of the movable crushing jaw are variable. The unit also incorporates a feeder hopper and discharge conveyor that provides for efficient ore handling through the machine. Tests demonstrated the M44 Crusher's high capacity, efficiency and reliability. During testing, it crushed over 120,000 tons of materials of up to 32,000 psi compressive strength at production rates in the 200-350 tons/hour range. The unit operated smoothly under simulated low-headroom conditions, and Proved readily transportable.

Jan 1, 1983

The above referenced contract between Badger Manufacturing Corporation and the U. S Bureau of Mines was executed June 30, 1975, as a result of the request for proposals for innovative machine concepts. We selected the cutting machine category because of the obvious lack of technical progress in this field for many years: Phase I of the contract required blasting fragmentation tests to determine proper blasting patterns for use with the auger-type kerf cutting machine. Phase II required design concept development for a machine capable of cutting a circular void as an aid to blasting.

Jan 1, 1975

By D. D. Bush

Based on the results of this study, the underhand cut and fill stoping method, with mass destressing, is an effective method for controlling rock bursts and falls of ground for deep mining in the Coeur d'Alene Mining District. The procedure can be utilized to pull highly stressed pillars by converting from conventional overhand stoping methods or used as a primary recovery system. During the demonstration, only one minor rock burst occurred, with no injuries. The system facilitates accurate placement of vertical boreholes for effective mass destressing. Each mining cut is filled with cemented sandfill overlying a timbered mat that forms the back for the succeeding cut. For this demonstration, a cemented fill was mixed on the surface and piped to the stone. Costs for pillar recovery by this method are comparable and are considered cost effective over conventionally timbered overhand mining as a pillar recovery method.

Jan 1, 1982

By Steven D. Wirch

Abandoned underground coal mine areas must either be sealed or ventilated to comply with federal mine regulations. Ventilation of these abandoned areas is often impractical due to roof falls and inadequate primary mine ventilation. If the area is sealed, a very complex ventilation system is set up. In which the gob "breathes" in and out due to barometric pressure fluctuations. The Gob Assistant is a computer program (for use on IBM compatible personal computers) which allows the prediction of air flows into and out of a sealed mine area. Gas flows with applicable control techniques are also modeled. This information is presented to the user who will decide which control technique, or combination of techniques will ultimately be applied. The Gob Assistant is an intelligent gob simulator that can reduce the guesswork involved in predicting the effects of sealing and control techniques before they are applied. This paper provides the fundamental principles upon which the Gob Assistant is based, verification of these principles, and an explanation of how these principles were integrated into the Gob Assistant.

Jan 1, 1988

By Lorenz E. Sieffert, Lawrence B. Berger, H. H. Sehrenk, Ralph W. Stewar, James A. Gale

"INTRODUCTION The purpose of the investigation discussed in this article was to evaluate the toxic hazard from gases produced when thermosetting plastic materials used for electrical insulating purposes are burned or thermally decomposed in enclosed spaces. For brevity the term ""toxicity"" is used throughout the article to refer to the nature of gases produced under these conditions. A need for immediate study of the problem was created as a re¬sult of the battle damage reports received from various United States Fleet units. These indicated that the fumes emitted when these materials were burned or thermally decomposed had, in several instances, resulted in toxic atmospheres. In attempting to develop a suitable test method for evaluating toxicity, it was recognized that no single test procedure could be expected to duplicate the variety of conditions that might exist in an actual fire aboard ship. In view of the immediate need, however, it was felt that considerable information could be obtained, at least to classify comparatively the several types of materials as to the toxic effect caused by burning or thermal decomposition, through the development of a sound empirical method which could be applied to all of the materials. On this basis, it was decided to modify the Navy flame resistance test for thermosetting plastics to render it applicable to the determination of the toxic, gases evolved when this test was employed. A wide variety of materials was tested, both molded and laminated, to cover the types commonly used by the Navy in electrical applications. Toxicity determinations were conducted at the Bureau of Mines Central Experiment Station, Pittsburgh, Pa. Parallel tests, to determine the flame resistance of the materials, were conducted at the Material Laboratory, U. S. Navy Yard, New York, N. Y."

Oct 1, 1947

By K. K. Kershner

The purpose of this investigation was to develop methods, on a laboratory scale, for recovering tin from Bolivian metallurgical slimes. Petrographic and chemical analyses were made of slime ore fractions from several well-known tin operations. High percentages of the total tin were volatilized as chlorides at temperatures below 600° C. Under optimum conditions reaction rates were relatively rapid, and the chloridizing reaction approached completion. Owing to the low temperatures involved and the high yields of tin, the process was considered to have possibilities for treating Bolivian slimes on a commercial basis. ACKNOWLEDGMENTS Appreciation is hereby extended to the Patino Mines and Enterprises, Inc., of Bolivia, for supplying slimed tin ores that were used in the experimental work. This company has since been nationalized.

Jan 1, 1959

The Federal Coal Mine Health and Safety Act of 1969 limits to 2 milligrams per cubic meter (for dust containing a maximum of 5% quartz) the average respirable dust concentration to which individual miners may be exposed. Section 205 of the Act directs that an appropriate exposure formula for dusts with quartz content in excess of 5% be established. This formula, entered in F. R. Document 70-12351 filed September 16, 1970, is 10 milligrams per cubic meter divided by % quartz. Thus, the total respirable dust exposure permitted limits the quartz to a maximum of 100 micrograms. For example, if % quartz is 5%, 10 mg/5 = 2 milligrams, and (.05) (2 mg) = 100 micrograms. Similarly, if % quartz is 10%, 10/10 = 1, and (.10) (1 mg) = 100 micrograms, etc. If the % quartz is less than 5%, the 2 mg/M3 limit prevails.

Jan 1, 1974

By D. Gearhart

Full-scale tests are conducted on mine roof supports using protocols developed by the National Institute for Occupational Safety and Health (NIOSH) using the unique capabilities of the Mine Roof Simulator (MRS). These protocols simulate the loading conditions that the support will be exposed to in an underground mine to determine the performance capabilities and limitations of the support. Some tests are conducted with rigid boundary conditions, creating uniform contact and near ideal axial loading conditions. These tests are used to determine the ultimate performance potential of a support, including the strength, stiffness, and stability. For prop supports where stability is a critical design issue, tests are implemented to induce buckling by a modified end condition, eccentric contact, or biaxial loading. It is important to determine the cpacity of the support design when the support is subjected to unpredictable loading conditions. This paper examines the effect of end conditions and load profiles on prop support performance and applies a new analysis methodology based on eccentric loading to determine a factor of safety for load capacity. Recommendations for installation practices that minimize eccentricity and therefore preserve capacity are also provided.

By L. A. Neumeier

The Bureau of Mines evaluated the properties of zinc alloys containing 25 to 40 wt pet Al and 0 to 0.7 pet Mg. Microstructures, hardness, and tensile properties were evaluated for material as extruded at 285° C, solution treated at 300° to 400° C, and subsequently aged at 100° to 200° C. The alloys without magnesium are characterized by low hardness and strength with high tensile elongation and reduction in area. It was verified that magnesium effectively retards the Zn-Al eutectoid transformation below 275° C and markedly increases hardness and strength with decreases in ductility. Solution treating at 350° C results in large grain sizes and gross embrittlement. Subsequent aging of the Zn-Al-Mg alloys at 200° C restores ductility substantially and stabilizes the structures, but strengths are considerably reduced. Combined strength and ductility properties are better for the as-extruded condition than for any heat-treated condition. There is usually little advantage in overall tensile properties from increasing magnesium above 0.1 pct.

Jan 1, 1971

By C. E. Wood

A special appropriation made by Congress in July 1940 provided funds for the investigation of methods for recovering manganese from low-grade [ ] domestic deposits. These funds were assigned to the United States Department of the Interior, Bureau of Mines. A committee, identified as the Technologic Committee on Manganese of the National Research Council, National Academy of Sciences, was appointed to recommend the allocation of the funds for investigation of the more promising projects.

Jan 1, 1942

By C. E. Wood

A special appropriation made by Congress in July 1940 provided funds for the investigation of methods for recovering manganese from low-grade [ ] domestic deposits. These funds were assigned to the United States Department of the Interior, Bureau of Mines. A committee, identified as the Technologic Committee on manganese of the National Research Council, National Academy of Sciences, was appointed to recommend the allocation of the funds for investigation of the more promising projects.

Jan 1, 1942

By Laurance L. Oden

The Bureau of Mines is developing melting data for binary combinations of the alkaline earth fluorides and yttria to facilitate the formulation of slag compositions. The present report deals with the CaF2-Y203 system for which solidus and liquidus temperatures and solid solubilities were determined. The information is presented as the phase diagram. All specimen compositions were blended from high-purity materials and encapsulated in Mo or Pt20Rh prior toheat treatment. Liquidus temperatures were determined by ceramographic examination of heat-treated and quenched specimens. Solidus temperatures were determined by differential thermal analysis and by electron microprobe analysis of quenched specimens. Terminal solid solubilities were derived by parametric methods. The peritectic system was found to be pseudobinary due to the formation of yttrium oxyfluoride at temperatures near the liquidus. The peritectic point occurs at 7 mole pct Y203 and 1,438° ± 5°C. The terminal solid solubility of Y203 in CaF2 decreases from 7 mole pct at 1,438° C to 1 mole pct at 1,100° C, and the solubility of CaF2 in Y203 decreases from 9.5 to 7 mole pct over the same temperature interval.

Jan 1, 1970

By K. E. Tame

The Bureau of Mines is studying possible modifications in conventional uranium ore-processing steps to confine and permit controlled disposal of radioactive wastes. A potential method of minimizing pollution from radio-active nuclides, principally radium 226, in uranium mill waste streams is to reuse the waste solutions within the mill. Such reuse of waste solution in the Kerr-McGee Shiprock-type process was investigated in the laboratory. The Shiprock mill employs a two-stage acid-leaching process for dissolution of the uranium, countercurrent decantation for liquid-solid separation and washing, and organophosphorus solvent extraction for recovery of the uranium and vanadium from solution. The simulated use of barren raffinate instead of fresh water in the mill circuit was carried through a laboratory campaign of 28 interlocked leaching, washing, and solvent extraction cycles. About 99 percent of the uranium and 91 percent of the vanadium were dissolved from the are, Washing efficiency in the thickener circuit averaged about 99.5 percent when the pulp was washed with enough barren raffinate and makeup water to recover 2.5 tons of pregnant solution per ton of ore. The only solution discarded was that contained in the washed and thickened leach residue. A buildup of salts due to recycling of solutions did not adversely affect operation of the washing circuit.

Jan 1, 1962

By Samuel P. Harteis

Many mining operations rely on retention bulkheads to provide a barrier between impounded water and active mine workings. However, bulkhead failures can cause catastrophic flooding that puts the underground workforce at risk. Underground observations and evaluations of existing bulkheads indicate that a systems approach is required when building an underground water or slurry retention system. In addition to engineering the bulkhead, the designer must ensure the quality control of materials and workmanship of the bulkhead, the reaction of the mine strata when exposed to water under pressure, and methods to monitor the performance of the retention system. Researchers from the National Institute for Occupational Safety and Health (NIOSH), with the assistance of the Mine Safety and Health Administration (MSHA), conducted an extensive review of bulkhead permits submitted to the MSHA Technical Support office in Bruceton, PA. In addition, the researchers visited accessible bulkhead installations at undeground mining operations to gather information related to construction practices, maintenance issues, and monitoring and emergency response procedures. Several key items were identified that must be considered when permitting the installation of an underground fluid retention system.

Jan 1, 2008

Maps To Accompany Bulletin 418

Jan 1, 1941

By Terry J. Close

From 1981-84, Bureau of Mines personnel examined and evaluated mines and prospects in the highly mineralized 62,400 acre Inyo Mountains U. S. Bureau of Land Management (BLM) Wilderness Study Area (WSA), located east of Lone Pine, CA. The 62,400 acres studied is the part of the 87,145 acre WSA designated as suitable prior to February 28, 1983. The WSA is underlain principally by quartz monzonite and quartz diorite that have intruded sedimentary and volcanic rocks. Three types of mineral deposits are present: 1) gold in fissure veins, 2) silver in fissure and replacement veins, and 3) talc in metasomatic lenses. Of the 84 nines, mills, and prospects examined, 54 are significant: 1) 5 in the intrusive rocks total about 4.4 million tons of inferred marginal gold reserves averaging 0.24 oz gold and 0.74 oz silver/ton; 2) three associated with intrusive-sedimentary rock contact zones total about 280,000 tons of inferred subeconomic silver resources averaging 7 oz silver/ton; 3) 27 gold and silver occurrences in the intrusive and sedimentary rocks total about 1.2 million tons of material in poorly defined bodies too small or low grade to be resources; 4) 15 gold and silver occurrences in the intrusive and sedimentary rocks are too poorly exposed to estimate tonnage and grade; and 5) four talc deposits along intrusive-sedimentary contact zones have inferred marginal reserves totaling about 640,000 tons. The marginal gold reserves at $450/oz might be profitably mined (reserve) at a gold price of about $600/oz and the subeconomic silver resources at a silver price in excess of about $27/oz. The marginal talc reserves might become minable at prices of about $50/ton and $80/ton for unprocessed and processed talc, respectively, after present supply sources are depleted. At most of the 54 significant mines and prospects, additional reserves or resources would likely be disclosed by trenching or drilling. Present in the WSA are 13 gold mills, numerous small pits and cuts, 270 underground workings totaling about 36,000 ft, and 80 mining benches totaling about 11,000 ft. Gold, silver, or talc were produced from most of the workings. A total of 1,561 lode and 18 placer samples were taken.

Jan 1, 1985

By Mary E. Cocklan-Vendl

Regulatory processes associated with development of major mining operations in Alaska and British columbia were evaluated using specific case studies. Included were one hard rock mine in Alaska (Red Dog Mine), one hard rock mine In British Columbia (Snip Mine), and one offshore gold dredging project in Alaska (WestGold SIMA). Based on a comparison of the three case studies, it became clear that the primary incentives for cost effective permitting are: 1) early and continuing coordination of proposed project plans, designs and schedules with key regulatory agencies and local area residents and 2) development of a sufficient level of baseline information on air quality, water quality, wetlands, endangered species, fish and wildlife, and socia-cultural conditions to support the required permit application. The U.S. permitting process worked in much the same way as the Canadian permitting process. Disincentives of mine permitting include high initial costs for baseline data gathering. However, a relatively high early investment resulted in more efficient permit acquisition and reduced long-term monitoring requirements. A common problem Identified was the inadequate supply of trained agency personnel with the requisite technical and permitting experience. This sometimes resulted in poor decisions and unnecessary changes in project plans and schedules.

Jan 1, 1993

By W. S. Sanner

Anthracite was used extensively as a fuel in iron metallurgy from 1840 to 1880. In 1874, 226 of the 680 blast furnaces in the United States were operating on anthracite and producing almost one-half of the Nation's pig iron. However, by 1890, railroad expansion, the development of western iron-ore reserves, and the growing use of coke decreased the importance of anthracite as a metallurgical fuel. As a result, the last blast furnace designed exclusively for anthracite use was built in 1891. Because of the increased energy requirements of our expanding national economy, the abnormally high demands during national emergencies, and the proximity of anthracite deposits to eastern steel-producing areas, interest has grown in again using anthracite in iron metallurgy. Estimates of anthracite reserves indicate a 300-yr. supply at a production rate of 30 million tons per year. These large reserves dictate the development of an adequate technology for the use of anthracite by the metallurgical industry.

Jan 1, 1961

By O. C. Blade

Studies on more efficient utilization of petroleum have been made for 50 years by the Bureau of Mines. As part of this work, the Bureau has analyzed thousands of samples of crude oil by its standardized routine method, and many of these analyses have been published, sometimes in special compilations, other times in connection with reports of research on petroleum. This report is a finding index for all analyses published from 1921 to 1959, and brings up to date the information in Information Circular 7470 3 and in the appendix of Bulletin 490.4 The routine method of analysis and the equipment originally were described in a report by Dean and associates. 5 This report has long been out of print, but Bulletin 490, bringing the procedure and its modifications to date, was published in 1951. 6 Briefly, the procedure consists of testing, by standard methods, small samples of a crude oil for gravity, sulfur, color, viscosity, pour point, and (more recently) nitrogen; and, by a standardized procedure, distilling a portion of the crude oil and determining certain properties on the separated fractions and residuum. Careful records are made during the procedure, and the distillation data obtained are used to compute the approximate amounts of products present in the sample--such as percentages of gasoline, kerosine, gas oil, and lubricants. The principal data and results are recorded on a standard analytical report form. An analysis of a sample of crude oil from a recently developed field is shown in table 1. Compilations of these analyses, sometimes in tabular form and usually for specific geographic areas, are published from time to time. Analyses often are included in connection with other studies, such as engineering field reports.

Jan 1, 1959