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By R. L. Gall

This report describes Bureau of Mines experiments in gasifying coal in a helium-heated tube-coil reactor. The purpose of this work was to investigate helium as a medium for transferring heat from a nuclear reactor to gasify coal or for use as high-temperature process heat. A laboratory-scale system was designed and constructed to demonstrate feasibility. In preliminary tests with this system, in which the coal was fed as a water slurry, the helium-heating and recycling equipment operated well. Considerable difficulty was experienced, however, in preheating coal slurry to the desired range of 400° - 1,000° F. without plugging the preheaters. Five different preheaters plugged with coke or with salts leached from the coal. The longest operating period wan 12 hours. These difficulties were partly due to the relatively small equipment and flow rates. The gasifier processed l pound per hour of low-rank coal at 300 p.s.i.g. and 1,800° F., with the carbon conversion limited to 20 to 30 percent by the short residence time and slow heat-transfer rate.

Jan 1, 1962

By William H. Lesser

A recent survey of pumping plants in the anthracite region of Pennsyl¬vania showed that more than 90 percent of the pumps in use are the horizontal centrifugal types (1).2/ This report on the design and operation of centrifugal pumps should be helpful to engineers of the region who must select pumps that are best suited to particular pumping conditions in anthracite mines. Before a centrifugal mine pumping plant is designed, the special features of the pumps that may be used should be considered, especially when low repair costs and continuous operation during flood periods are prerequisites, and when acid mine water is to be pumped. Two important advantages of a centrifugal pump are that the flow is continuous and that it can be throttled without developing excessive pressure or overloading its driving unit.

Jan 1, 1950

By D. D. Runnells

This study focused on the chemical reactions between uranium tailings fluids and cores of subjacent bedrock from the site of the Cotter Corporation uranium mill at Canon City, Colorado. Actual and synthetic tailings fluids were forced through cores of bedrock. The pH of the effluent solutions was the dominant control on the behavior of dissolved species in solution. The pH depended on the presence or absence of calcite cement in the rocks. Calcite neutralized acidic raffinates and caused the precipitation of iron, manganese, aluminum, and possibly uranium. Chloride, sulfate, and sodium were not retarded upon passage through the cores, and sulfate and chloride should be useful as tracers of escaping tailings fluids. Zinc, copper, cobalt, nickel, uranium, and vanadium exhibited high mobility under acidic conditions and were strongly retarded at elevated pH. Calcium was released due to dissolution of calcite and ion-exchange. Magnesium was not retarded in concentrated solutions, but showed moderate retardation in dilute fluids. Potassium and ammonium both showed early retardation followed by breakthrough and mobility. The behavior of molybdenum was strongly dependent on pH, with retardation at low pH and mobility at elevated pH. Selenium was highly mobile under all conditions. Selenium should be a better tracer than molybdenum for many situations. Precipitation of carnotite appears to control the solubility of uranium and, possibly, vanadium. With the exception of the precipitation of aluminum and silica, all reactions were rapid.

Jan 1, 1983

By Loren R. Anderson

This is an Appendix of Volume I. In contains the results of the electric cone penetrometer soundings from the second phase of the testing program.

Jan 1, 1982

By Duane L. Abata

Toxic gases produced by the detonation of six explosives were measured in an underground hardrock metal mine during actual mining operations. The six explosives included two semi-gelatin dynamites, three slurry explosives and an ammonium-nitrate, fuel-oil/ammonia dynamite combination. Explosives were detonated at the face of a drift and the toxic gases produced by the detonation were trapped to the end of the drift by a bulkhead located a short distance away from the face. Toxic gas concentrations were then measured with direct readout instruments and together with the containment volume, the toxic gas volumes per mass of explosive were calculated. Toxic gas measurements were found in the following ranges (ft3/lbm): N02 0.010-0.035; N02, 0.003-0.019; CO, 0.08-0.30; S02, 0.00-0.05; and C02, 0.7-1.8. Results showed that toxic gas production (ft3/lbm) correlated with the densities (kg/m3) and energy densities (kJ/kg) of the explosives tested.

Jan 1, 1978

By Karl E. Starch

This Bureau of Mines report is a background study of severance taxes on mineral production. The rates, bases, and other features of State severance tax legislation as of March 1978 are presented, as are the amounts of State severance tax collections for fiscal year 1977, Some statistical comparisons between severance tax collections, total State tax collections, and total value of mineral production in the States involved are presented to portray the relative importance of severance taxes both in State tax revenue systems and in mineral industry revenues. A general discussion of the purposes and principles of taxation, the unique nature of a mining enterprise, the various types of taxes imposed on mineral production, and the character and rationale of the severance tax and its impacts on mining firms sets the severance tax in perspective. A bibliography of materials on the severance tax is included.

Jan 1, 1979

By Don] [Hinkle

Unable to Load

Jan 1, 1977

By Kenneth Trelewicz

This report describes the total effort that went into developing environmental test criteria for general mine instrumentation. The project was a two-phase effort. Phase I consisted of research and mine visits to develop an environmental profile for mine instrumentation. The profile was translated into general requirements and then into test requirements. A review of existing government and commercial specifications was performed to determine if they matched mine instrumentation test requirements. Finally, a set of environmental test procedures was developed for the testing of mine instrumentation. Phase II consisted of selecting and purchasing sample mine instrumentation and subjecting them to the previously developed tests. The purpose was twofold: (1) to evaluate the criteria developed for use as an instrumentation test document and (2) to determine the effects of the various criteria on a representative sample of both proven and newly developed instrumentation. The test criteria were then modified, based on the results of the testing, and are listed therein.

Jan 1, 1981

By W. L. Cornell

The Missouri lead ores are the only domestic sources of cobalt presently being mined and processed for other materials. They represent the best short-term solution for meeting up to 13 pct of the Nation's strategic and critical cobalt needs from domestic sources. Presently, the cobalt is lost as an impurity in the copper, lead, and zinc concentrates and in the mill tailings because the technology to recover it with minium impact on present production does not exist. This paper presents results of research, built upon earlier Bureau of Mines laboratory research, to enumerate the problems encountered in cobalt recovery from the copper concentrate under actual mill conditions; to present alternative solutions to these problems; and finally, to describe the best available technology for cobalt recovery within the imposed constraints. Mineralogical analyses showed the cobalt present as a distinct mineral phase, predominately siegenite, amenable to a physical separation method such as froth flotation. Flotation was chosen for recovery because of easy adaptation by the mills. Unit processes of grinding, conditioning, and flotation were studied individually and in concert, and a series of continuous tests were run based on the parameters developed to obtain engineering data for subsequent economic analysis. Overall cobalt grades of 3.00 wt pct at a recovery of 64.0 pct were achieved.

Jan 1, 1987

By A. W. Hall

A nuclear method was developed for continuously and automatically deter-mining the moisture content of coal flowing through a bin. Fast neutrons from a 1 curie americium-beryllium source penetrate the coal, are thermalized (slowed down) by hydrogen in the moisture, and are counted by a thermal neutron detector. The difference between the number of these thermal neutrons and those thermalized by dry coal (in a reference drum) is a measure of the moisture content of the coal. A materials handling system was developed and in tests at a commercial coal preparation plant, moisture in coal was monitored continuously within 0.2 percent of values determined by conventional means. The meter responded rapidly to change in moisture content, making it adaptable to automatic process control, and was operated for 1 year without malfunction or recalibration. Shielding of the source by the coal kept the neutron flux level at the bin wall less than 1 milliroentgen per hour, a safe level for personnel.

Jan 1, 1973

By Robert Merritt

Approximately 2,500 tons of low-grade uranium ore were used to conduct a field-scale heap leaching test as well as throe column leach tests. The ore used to construct the field-scale heap leaching test had a grade 0.023% U308 while the ore used fur column leach tests had a grade of 0.027% U308. The ore was crushed to minus 4 in. The field-scale heap was constructed on a clay base with parallel effluent lines running under the heap spaced 7.5 ft apart. The heap was leached for 45 days, drained, washed, and dismantled. Based on residue analysis, approximately 205 tons of ore were leached with a final U308 extraction of 96%. The heap was 17.9 ft in height and leached in a near-vertical pattern down to approximately 1 ft, at which point the leached zone become bell-shaped. Two 8-ft column charges and one 18-ft column charge were leached for 36 and 45 days, respectively. Based on residue analyses, all U308 extractions were greater than 96%. The conclusions generated by the studies showed that (1) flow rates were similar for column leaching and field-scale leaching, (2) final U308 extractions were the same for both types of leaching; however, the deeper ore beds tended to require longer leaching times, and (3) the reagent requirements were reduced with increased bed depth.

Jan 1, 1980

By Russel R. Bohn

The objectives of this study were to: (a) determine the state of the art for the control effectiveness of various chemical dust suppressants, (b) field test the effectiveness of the dust suppressants, and (c) develop technical guidelines for selecting and implementing cost effective tailings pond dust control programs. Chemical stabilizers evaluated under field conditions were: Coherax, Calcium Lignosulfonate, Nalco 656, 655, and Magnesium Chloride. Testing in the field utilized a portable field in-situ wind tunnel. The wind tunnel was placed on the tailings surface and simulated wind speeds of up to 80 mph were used to determine wind erosion threshold velocities. Emission rate testing was performed with the wind tunnel through the use of a real-time cascade impactor. A control cost effectiveness evaluation was performed to determine how efficient the chemical stabilizers were on a dollars expended per acre basis.

Jan 1, 1983

By Zsuzsanna Zborovszky

Investigation of the discharge duration power and current relation required for ignition. The current and power amplitude-discharge time curve was found to flatten out over 3 ms. It is concluded that discharges having at least 3 ms power maximum are required for reliable testing of the ignition limit for resistive circuits. Investigation of the effect of molten cathode on the discharge duration and igniting ability of the discharge. The surface tension of the liquid metal causes a very fast separation and consequently a much shorter discharge duration than the solid electrode would have. The minimum discharge voltage effect overrides the effects of the temperature of electrode, material, or atmosphere. Investigation of the effect of different surface layers on the discharge duration. Oxides and sulfates were found to give significantly longer duration than the "clean" metal itself in most cases. The lowest ignition current was obtained with CdS04 coatings. Ignition was obtained with 0.7A at 30V, which is below the corresponding minimum igniting current obtained from the BASEEFA curve for circuits containing Cd, Zn or Mg.

Jan 1, 1977

By C. B. Davison

One goal of the Bureau of Mines is to conserve the Nation's mineral resources by developing improved performance materials. Consistent with this goal, the Bureau conducted studies on the formation of undesirable cristobalite in seven different fire clays used as refractories. The studies employed scanning electron micrography, chemical and X-ray analyses, and pyrometric cone equivalent determinations to examine the sample clays and determine the effect of thermal history and stablilizing additives on the amount of cristobalite in various calcines. This research has indicated that as fire clay calcining temperatures increased from 1390° to 1,490° C there was a gradual decrease in the percent of cristobalite present in the calcines and a progressive development of mullite crystallization. No cristobalite was found in fire clays calcined above 1,550° C, but cristobalite reappeared when the calcines were reheated to temperatures between 1,400° and 1,500° C. The research also revealed that additions of lithium fluoride (LiF) prevented formation of cristobalite in fire clay calcines.

Jan 1, 1979

By Joan Weinberg

The economy continued to expand during the third quarter, as real GNP rose at a seasonally adjusted annual rate of 3.8%, up from 2.5% in the second quarter (table 1). Continued job gains (see below), higher incomes, and an increase in installment debt, resulted in a nearly 20% increase in consumer spending on durable goods. Consumer expenditure on nondurables fell slightly, while spending on services continued at a moderate pace. Nonresidential fixed investment climbed nearly 24%, as producers purchased more durable equipment. Residential fixed investment was adversely affected by rising interest rates, which slowed new home construction from January to August, 1987 to a rate 11.2% below a comparable period in 1986. Net exports of goods and services deteriorated slightly, after three consecutive quarters of improvement. The volume of net exports has risen 15% for the year, contributing to economic and employment growth, but large price increases on imports have slowed the improvement in the nominal trade balance. Although U.S. goods have declined in price relative to foreign goods because of the devaluation of the dollar, faster growth in exports is hampered by austerity programs in developing countries, and emphasis in Germany and Japan on curtailing inflation and fiscal deficits.

Jan 1, 1987

By F. A. Penning

An experimental and analytical investigation was conducted on a recoverable pit bottom buffer. Work was conducted at the Colorado School of Mines using the U.S. Bureau of Mine-s free fall test tower. The four-sided butter, one of several designs by Cable Belt Ltd., was constructed of reinforced rubber slabs. The kinetic energy of falling weights, 1670 to 6000 lb, was absorbed by the flexure of rubber slabs loaded along their edge. A series of constant energy, 3000 ft-lb and maximum design velocity, 600 fpm tests were conducted. Static testing of the buffer established the load-deformation behavior. A large hysteresis loop plotted above and below the data published by the manufacturer. Creep was evident during; the loading Lend unloading cycle. Electronic instrumentation measured deceleration using your accelerometers; overall and intermediate movement was found from four displacement transducers; bending strains were recorded at four locations; and base reactions were measured by using four load cells. Data were recorded on tape and played back on a recording oscillograph. High speed movies were taken of all the tests. Symmetry of response and rebounds, when they occurred, were noted. From the displacement-time and load-time data, maximum decelerations were calculated by four methods and different assumptions. Good agreement was found from these approaches. Impact loads ranged from a low of 0.7 to a high of 6.1 gs. A dynamic computer model was written for the response of the buffer. Displacement-time, and acceleration-time plots show close correspondence with experimental data for the ten experiments. Data from accelerometers, displacement transducers, strain gages, and load cells are included. The computer program listing, and displacement-time acceleration-time plots are also presented.

Jan 1, 1980

By Terry R. Neumann

In 1989, the Bureau of Mines conducted a mineral resource investigation of the 52,350-acre Jersey Jack study area, located in the Clearwater Mountains of north-central Idaho. Twenty-eight mines and prospects were examined, and 483 rock, placer, and petrographic samples were collected during the field study. Two properties contain gold resources; mining company data show the Robinson Dike mine contains an estimated 940,000 tons of "drill proven and probable reserves" averaging 0.041 oz/ton gold, and the Bureau of Mines investigation showed the Blacksand placer mine contains an estimated 64,000 cubic yards of identified placer resources averaging $8.13 in gold per cubic yard. Sample analyses from other properties indicate that gold resources are likely to exist; however the low tonnage, narrow, fissure-vein type deposits would require mining by relatively high-cost underground methods and would be subeconomic at a gold price of $400/oz.

Jan 1, 1991

By W. W. Odell

Engineers interested in the manufactured-gas industry have witnessed p pronounced improvements in gas-generating equipment and marked changes in operating procedure during the past decade. In spite of these changes, however, the trend of development in the near future seems to be doubtful. Uncertainty exists mainly because no one can yet accurately calculate the number of years which will elapse before petroleum products become too expensive for, general use in making gas. Research in this field has been active, and the ultimate results are awaited with interest. Some engineers predict that in the future coking coal will be carbonized on such a large scale that coal gas will be used (straight or modified) for city distribution; others maintain that gas oil will be used in large quantities in the production of base gas; they believe that it will be economical to use oil even at appreciably higher prices. The question involves, among other; factors, consideration of initial and relative costs of equipment, flexibility of operation, salability of coke, cost of distributing different gases, and the relative value of by-products, It is common belief that for many years large quantities of oil will be used in gas-making, particularly in the generation of peak gas or that water gas will be used for the synthetic production of hydrocarbons to enrich additional water gas. In this paper interest centers in a discussion of the practicability of employing synthetic processes in view of reported investigations of the chemistry of the synthetic reactions. For many years it has been known that the chief components of water gas would react chemically under proper conditions to form methane. As long ago as 1903 a patent3 was issued in this country for a gas-making process which included the synthetic production of methane. More recently the studies of numerous investigators here and abroad have shown that besides methane it is possible to produce other paraffins, olefins, and additional, materials adaptable for enriching water gas or for other uses. The question arises: In what manner, if at all, can such processes be incorporated, as a part of the gas-making scheme in a city-gas plant?

Jan 1, 1928

By T. J. Ballard

The Rickard mine in York County, S. C., named for the original owner, Alexander Rickard, was operated about 50 years as. No records are available of the quantity of corundum shipped. Pratt states, "Many tons were picked up from the surface and shipped." The mine was visited on August 6, 1943, by the author, accompanied by Gilbert W. Withers of Atlanta, Ga. Investigation of the property was begun by the Bureau of Mines after some initial work by the Mi-Cor Corp., a company organized by Gilbert P. Withers of Atlanta to explore the property. In conducting the Bureau program, 754 linear feet of trenches were dug, 110 feet of old drifts cleaned out and examined, and 38 feet of shaft retimbered.

Jan 1, 1948

By Herman O. Ankenbruck

Analyses of statistical data indicate that haulage accidents are one of the largest sources of injuries and fatalities in underground coal mines, and that the rate of accidents in transportation has been increasing during the past few years. These previous analyses were performed by correlating accident or fatality data at a rather high level of miner activity. In this present investigation, underground surveys were made by observing conditions and activities in some detail at a rather low level of activity in an attempt to understand factors contributing to hazards in the specific situations observed. The aim of the current study was to derive preventive measures that might obviate the hazardous conditions and unsafe acts observed; and, following this, to provide recommendations for additional research and development to reduce accident potential in underground transportation. The major project tasks are diagrammed together with the task outputs in figure 1-1. Initially, a preliminary study of ell underground haulage operations was performed in order to establish the kinds of data needed and to provide the rationale leading to the data requirement. At the same time, the various types of haulage equipment used for each operation were defined. A preliminary analysis of each type of haulage operation was performed in order to establish the sequence of tasks required to operate haulage equipment. These tasks were transferred directly onto observation forms, and were used in developing interview forms. In parallel with the task analysis, a review was made of accidents and hazards that might occur during each type of operation.

Jan 1, 1975