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By E. S. Leaver

Experiments dealing with the dissolution of silver by cyanide from various silver minerals-were reported, several years ago.4/ This work showed that the silver in some silver minerals is completely and readily soluble in cyanide solution, whereas other silver minerals must be given special treatment before or during cyanidation to obtain much dissolution of the silver by cyanide. Flotation as a method for treating silver ores has not been studied much, except in the case of base-metal ores carrying silver, Particularly lead-silver ores. However, many mills now are concentrating gold ores by flotation, and when such ores also contain silver the recovery of the silver by flotation is of considerable importance. Moreover, many mines contain ore in which silver is the principal valuable constituent. Some of these ores are amenable to cyanidation, but the cost of a cyanide plant may be prohibitive because of limited ore bodies or other factors. In such instances the successful application of flotation would mean that the property could be operated.

Jan 1, 1939

By W. H. Rinkenbach, C. A. Taylor

"Among the recently patented detonating compounds that have been suggested as substitutes for the commonly used fulminate of mercury is the normal lead salt of trinitroresorcin, or styphnic acid. As no data concerning its use or practi¬cability were available, a study of its properties was made in the explosives laboratory at the Bureau of Mines experiment station at Pittsburgh, Pa. This paper embodies the results obtained.Normal lead trinitroresorcinate was first prepared and patented*** by Herz; it probably found some use during the World War, but no record of its performance is available,Preparation of Lead Trinitrpresorcinate.In his patent specifications, Herz states that the normal salt may be obtained in a quantitative way by precipitating a multiple of the equivalent weight of the lead salt of a strong inorganic acid - such as lead nitrate - in the presence of a weak organic acid - such as acetic acid - by heating with a Teak solution of the alkali-metal salts or alkaline-earth salts of trinitroresorcin. Herz gives the following example: 245 grams of dry trinitroresorcinand 290 grams of crystalline sodium carbonate are dissolved in in 18.8 liters of boiling water, to which 77 c.c. of glacial acetic acid is added. The toiling solution is mixed with a boiling solution of 650 grams of lead nitrate in 1.4 liters of water, stirring rapidly; and the mixture is boiled for two minutes, after which it is cooled quickly with constant stirring. The precipitated crystals are then filtered off, washed several times with cold water, and dried."

Oct 1, 1923

By Wm. W. Odell

For a number of years there has been a very appreciable annual,, increase in the production and recovery of natural gas and natural-gas gasoline2 in the United States the latter product being used largely for blending with gasoline from petroleum in the production of motor fuel. On account of the increased amount of oil cracking in the production of gasoline and the accompanying increased percentage of low-boiling constituents in the resulting product, the specifications for the natural gasoline suitable for blending have been altered, that is, the amounts of propane and butane which it can contain have been limited. The result has been that large quantities of the latter materials are wasted because there has been no ready market for thorn in large quantities. Because of this wasteage and because it is probable that large quantities of there and similar materials will be produced in the near future us a result of the more general use of oil cracking processes, a study was made by the Bureau of Mines, under a cooperative agreement with the assistance of the Phillips Petroleum Company, of the suitability of these materials alone or in mixtures for use as gas enricher in the carburetion of water gas for city distribution. This investigation included: (a) A study of the properties of the low boiling members of the paraffin series including pentane with particular reference to their utilization as gases.

Jan 1, 1927

By Paul W. Johnson, Ralph C. Kirby, Frank A. Peters

Alumina can be recovered from clay , using 30 percent nitric acid for digestion . Calcined clay is crushed and then digested at 325 ° F and 85 psig pressure with less than stoichiometric nitric acid required to form normal aluminum nitrate . In this way , a solution containing both normal aluminum nitrate , Al ( NO3 ) 3 , and basic aluminum nitrate , assumed to be Al ( OH ) ( NO3 ) 2 , is formed , and in which iron is virtually insoluble . The solution is filtered and then concentrated in vacuum evaporators to crystallize normal aluminum nonahydrate . The crystals are washed with 50 percent nitric acid and then decomposed to alumina and nitrogen oxides . The design that has been developed for this process is based on published work . For a plant producing 1,000 tons of alumina a day , the estimated operating cost is $60.69 per ton of alumina , and the estimated fixed capital cost is $ 76 million using a Marshall and Stevens chemical equipment index basis of 240.0 . This process is not competitive under current economic conditions with the production of alumina from bauxite via the Bayer process . For lowering costs , future research should include study of leaching at lower temperatures under atmospheric pressure and alternate aluminum nitrate decomposition methods .

Jan 1, 1964

By W. E. Young, D. T. Delicate

This study was made to present the mining methods and costs of a uranium mine typical of other mines in the highly productive Westwater Canyon member of the Morrison formation in New Mexico. Four mining methods have been used at the Section 23 mine: the retreat- room-and-pillar method, a sublevel-slicing method (also called top-slicing), the horizontal-cut-and-fill method, and a modification of the ring-drill method. The application of the methods at this mine and at other mines in the area should be of benefit to operators with similar problems. Ore bodies in the Section 23 mine are irregularly shaped and vary in size, in rock strength, in moisture content, and in uranium concentrations; different mining methods are required and mining costs are not constant. A 6-month period of operation at the Section 23 mine was analyzed and mining costs, not including amortization, depreciation, or Federal taxes, averaged about $6.80 per ton.

Nov 1, 1963

By Stephen P. Holt

During the spring and summer of 1946, the Bureau of Mines put down 8 churn-drill holes and 9 diamond-drill holes, totaling 3,535 feet of bore, at the Blewett zinc-lead deposit in Jo Daviess County, Ill. Attention of the Bureau of Mines was first directed to this deposit by the Illinois State Geological Survey, which had investigated the Blewett mine. In the opinion of the Survey and the Bureau of Mines, the record of production and results of drilling previously done on the property were considered sufficient justification for continuing investigation to the north and south along a projection of the trend. This report describes the work done by the Bureau on this, property and presents the data obtained.

Jan 1, 1948

By Robert Bottge

When a company develops a mineral property in a remote area of Alaska, it must consider how best to house its personnel. This Bureau of Mines report examines the economics of two options: company towns and company camps. The price required to maintain a 15% discounted-cash-flow rate of return (DCFROR) was derived for hypothetical 1,000-st/d cut-and-fill mines and 50,000-st/d open-pit mines located in three different regions of the State, One set of hypothetical mines utilizes a townsite; the other utilizes a relatively new concept, a fly-in camp or commuting operation, in which two shifts of employees operate the mine and all associated facilities for 1 week before being replaced by a second crew. The study shows that operating costs were higher for mines employing the commuting option than for mines having a company town because of the additional wages paid for overtime hours; however, the price required to obtain a 15% DCFROR for the single-product copper concentrate, f.0.b. the mill site, was significantly lower owing to the lower investment costs for the camp-type operation. The economic advantage for those mines utilizing the camp increases from south to north and from the coast toward the interior.

Jan 1, 1986

By Noel N. Moebs

The coal wants at the Westland Mine in southwestern Pennsylvania consist chiefly of elongated, sandstone-filled channels with slickensided basal contacts. Tentatively identified as washouts, these channels are about 1,000 feet long and 300 feet wide, are erratic in occurrence and trend, and are difficult to delineate from the customary core drilling pattern. Roof conditions are hazardous adjacent to the washout contact, but roof stability is generally unaffected greater than 30 feet away.

Jan 1, 1981

By M. G. Zabetakis

The use of liquid hydrogen as a high-energy fuel introduces numerous hazards not ordinarily associated with the use of other more conventional fuels. These hazards are attributable to the unique properties of hydrogen in the liquid and gas states (table 1). Since little work has been conducted on explosion and related hazards of cryogenic fuels, a research program was undertaken to obtain basic data on such dangers for hydrogen and other combustibles under these conditions. These data were used to outline emergency procedures for protecting personnel and equipment when an accidental spillage of liquid hydrogen occurs and to establish a quantity-distance table for the storage of this fuel. The vaporization of liquid hydrogen from a surface is treated as a prob¬lem in heat transfer theory. Two extreme cases are briefly considered: (1) The transfer of heat occurs at constant temperature drop between, the boiling liquid and the hot surface, and (2) the transfer of heat is limited by the rate at which it can flow to the surface from a hot insulating medium. The available data indicate that the former case (1) is applicable when vaporizing from a conducting surface and, initially, when vaporizing from an insulating medium; the latter case (2) is applicable after initial flash vaporization has occurred from the insulating medium. The vaporization rate determines in part the rate at which flammable hydrogen vapor-air mixtures are formed above a spill area. However, the rates at which heat is transferred to the vapor, and air is brought in contact with it also are of importance. Accordingly, the distribution of flammable mixtures above a spill area was determined experimentally. In general, flammable mixtures were found to be both above and within the visible vapor cloud.

Jan 1, 1961

By A. J. Kraemer

This report is one of a series dealing with oil-shale-operations in foreign countries visited and studied by Bureau of Mines oil-shale technologists within the past 4 years. Many oil-shale deposits have been discovered in Brazil and studied with various degrees of thoroughness. In this report the major emphasis is upon the oil-shale concessions of Companhia Nacional de Oleos Mineraes, in the River Valley of the State of Sao Paulo, because this oil-shale deposit is one of the most promising in Brazil for large-scale utilization for the manufacture of liquid fuels and other products of oil-shale processing, and because the opportunity was afforded to examine the concession area and to study mining, retorting, and. refining operations on these shales. Results of detailed analyses at the Oil Shale Research and Development Laboratories of the United States Bureau of Mines, Laramie, Wyo., are reported, Analyses and other date dealing with other oil-shale deposits in Brazil have been compiled from many sources. As many data have been reported as could be correlated to indicate the range of variation of the several types of shale end similar material. The oil-shale deposits in Brazil differ widely in size, richness of the shale, and of the oil. Some deposits are situate& more favorably for exploitation than others.

Jan 1, 1950

By R. S. Fowkes

Jetstream pressure distributions and coal cutting rates were determined for a number of nozzles and under different operating conditions. The jetstrearn pressure distribution data were fitted to an assumed curvilinear equation by the utilization of a numerical least-squares technique with the aid of a digital computer. Subsequent manipulation of the approximation equation showed that the total force of the jetstream, rather than its maximum pressure or total kinetic energy per unit Lime, was the most significant quantity affecting the coal cutting rate. A shorter method for assessing the ability of a nozzle to cut coal was found.

Jan 1, 1968

By Carl L. Bieniewski

In a Bureau of Mines supply evaluation, the known uranium resources in the United States are estimated to have a total recoverable uranium oxide (U3O8) content of 3,132,400 tons at prices up to $69.32 per pound. Only those resources were evaluated for which sufficient quantity data are available and process technology exists for recovering uranium. A total of 160,800 tons of U3O8 is available at $8 per pound from ore deposits presently mined and an additional 244,700 tons available at prices up to $30 per pound from similar but usually lower grade deposits. A total of 2,726,900 tons of U3O8 is available from four other resources: copper leach solutions, wet-process phosphoric acid, Florida phosphate rock Leached zone, and Chattanooga Shale. These resources contain from 30,000 tons of recoverable U30, at a price of $7.52 per pound as a byproduct of copper leach solutions to 2,557,300 tons at a price of $69.32 per pound from Chattanooga Shale.

Jan 1, 1971

By R. W. Van Dolah

The Bureau of Mines t.ced its investigations into sympathetic detonation of ammonium nitrate (AN) and ammonium nitrate-fuel oil (AN-FO) to define the scaling law for safe separation from detonating AN-FO. Both missile- and non-missile-producing AN-FO donors, weighing up to 5,400 pounds, were employed with acceptors of the same size. The usual cube-root scaling law was not confirmed; exponents for the relationship S = f(Wx) for AN were 0.51 with non¬missile-producing donors and 0.61 for missile-producing donors. For AN-FO an exponent of 0.80 was indicated in the missile-producing case. AN-F0 in polyethylene bags appeared somewhat more easily initiated than bulk AN-FO. The efficacy of barricades in protecting AN charges was investigated. detonation distances were reduced from one-third to one-seventh when filled barricades were employed. The investigation was extended to dynamite with both types of donors. With 1,600-pound missile-producing donors and an equivalent weight of dynamite, initiation would be expected in 50 percent of the trials at 167 feet. The corresponding value in the non-missile case was 67 feet. The data developed in this program of sympathetic detonation will allow the development of a rational set of safe separation distances for AN, AN-FO, and explosives.

Jan 1, 1966

By O. C. Blade

The southeastern region of the United States is becoming more important as a petroleum-producing area, and it is receiving increasing attention from oil operators. In 1948 total production of crude oil from six southeastern States - Alabama, Florida, Kentucky, Mississippi, Tennessee, and Virginia - was 55,244,000 barrels, which represents 2.7 percent of the Nation's output during that year. Kentucky and Tennessee have produced crude oil since the early days of the industry, but the remaining four States have had production only few years. Data on annual production of crude petroleum in the six States are given in table 1.

Jan 1, 1950

By L. R. Burdick, J. F. Barkley

"The agglomerating index of coal is an index based upon the nature of the coke residue left when the standard volatile-matter determination of the well-known proximate analysis is made. In this determination a small amount of coal is heated in a container to about 950° C. (1,742° F.), at which temperature the volatile matter is driven off, leaving a coke formation. The coke residues for various coals are quite different in physical structure: and, for some time past, work has been done on studies of the nature of these residues in connection with the coking of coal. In 1934 Gilmore, Connell, and Nicolls proposed use of the agglomerating index for indicating the dividing line between noncaking coals and those having weakly caking properties. 4/ Its use was adopted in the standard classification of coals by rank as a requisite physical property index to differentiate semianthracite from low-volatile bituminous coal and also high-volatile ""C"" bituminous from subbituminous ""A"" coal, as shown in table 1, the standard coal classification adopted by the American Society for Testing Materials and the American Standards Association. 5./In studying the agglomerating properties of coals based on the coke residue the Bureau of Mines has adopted the notation given in table 2. Coals that in the volatile-matter determination give a coke residue either in the form of an agglomerate button that will support a 500-gram weight without pulverizing or a button that shows swelling or cell structure are considered to be agglomerating."

Nov 1, 1938

By James L. Eirls

The objective of this project was to improve a driver's field of view for large trucks used in the mining industry. Rearward viewing was enhanced by improving the rear-view mirror designs. Rear vision was accomplished using a closed circuit television system. Views ahead,, to the right, and downward were obtained with a blind area viewer (BAV). The BAV is a unique combination of fresnel lenses housed in a shielded, environmentally protected enclosure that produces an image of the area in front of and downward 70° and to either side of the BAV 300. The improved visibility devices were evaluated by long-term, in-mine testing. The right Bide mirror (RSM) and BAV provide the greatest improvements for the least cost and are commercially available. Application of the RSM and BAV should achieve a reduction in accident potential and greater vehicle productivity by enlarging and improving the equipment operator's visibility and making priviously blind areas and hazardous situations detectable.

Jan 1, 1982

By Ann G. Kim

Acid drainage from underground coal mines and coal refuse piles is one of the most persistent industrial pollution problems in the United States: This Bureau of Mines report reviews the acid mine drainage problem generally and describes research currently underway to combat it.

Jan 1, 1982

By Nan C. Jensen

Modern high-temperature metallurgical processes have created a demand for raw material for furnace parts and lining that not only will with-stand high temperatures is but will not react with the substance being melted in the furnace. Spark-plug insulators, laboratory ware, tanks for the glassmaking making industry, and saggers and kiln furniture for the chinaware and pottery trades also must be made of materials hat have high melting points. Among the minerals that can be employed for such refractory uses ore those commonly known as the "sillimanite group' -kyanite, andaluste, sillimanite, and dumortierite - and the allied minerals topaz and pinite. Consideration of the occurrence, properties, qualities, uses, and sources of supply of these commodities and the markets for them constitute the subject of this paper. General Features of Kyanite and Related Minerals Kyanite, andalusite, and sillimanite ire composed of three elements - aluminum, silicon, and oxygen ? and are called aluminum silicates. The have

Jan 1, 1943

By C. V. Jude

This U. S. Bureau of Mines (USBM) report presents results of stress analyses and field observations to investigate the effects of elevated trench drifts on the structural stability of rock mass zones surrounding a production draw drift in a mine utilizing a mechanized load-haul-dump (LHD) trench undercut panel caving system. A two-dimensional boundary-element mine stress model was developed to predict the locations and extent of damaged rock mass zones surrounding draw drifts where adjacent, parallel trench drifts are either elevated or not elevated above the LHD production draw drift level. A Mohr-Coulomb shear-failure criterion was obtained directly from in situ borehole shear test data. Hock-Brown shear-failure parameter values were computed from borehole-shear and triaxial test data. A procedure is described to estimate these parameters when a rock mass rating (RMR) value and triaxial data on intact samples exist, and no borehole shear test data exist Results indicate that trench drifts, elevated to the level equal to the height of the LHD production draw drift, would not minimize material damage nor significantly enhance the stability of rib and crown pillar zones surrounding production draw drifts in the mechanized LHD trench undercut caving panel investigated at this mine.

Jan 1, 2010

By Paul Hatmaker

This paper covers briefly the particular field of dolomite and magnesium limestone; certain uses of high-calcium limestone are mentioned only to show more clearly the limita¬ tions of the magnesian rocks. Such a comparison is helpful because magnesium carbonate is essential for some uses; for others it is immaterial; and for many its presence in an appreciable amount is objectionable. Magnesium carbonate, occurring as a rock resembling limestone or dolomite, is described in United States Bureau of Mines Information Circular 6437, Magnesite. Other com¬ pounds of magnesium are described in United States Bureau of Mines Information Circular 6406, Magnesium Compounds (Other Than Magnesite). Limestone, geologically, is a rock composed essentially of calcium carbonate; commercially, however, the term may include dolomite and magnesium limestone.

Sep 1, 1931