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By A. L. Engel

The Stayton Mining District in San Benito County, Calif., near Hollister, includes several square miles with many occurrences of antimony ore. The sample submitted for the test described in this paper came from a vein said to have been traced and sampled for 5,000 feet on the surface, 1,500 feet carrying 2-1/2 to 3 percent antimony and the remainder 1/2 to 2 percent. Thirty thousand tons 'With a content of 3 percent antimony are said to be blocked out. A drift of 200 feet on the vein has shown ore containing 4.2 percent antimony. The present sample assayed 3.8 percent. Previous flotation investigation of this are resulted in a recovery of only 71.6 percent in concentrates containing 56.8 percent Sb. It was desired to develop a method of treatment that would give better results. The antimony in the sample occurred as the mineral stibnite, Sb2S3, antimony sulfide.

Jan 1, 1949

By Clayton M. Rumsey

The U.S. Bureau of Mines investigated prospects and mineralized areas in and adjacent to the Indian Pass and Picacho Peak study areas in 1983 and 1984. The Indian Pass study area contains 33,640 acres and the Picacho Peak study area contains 5,450 acres. The study areas are located in the southeast corner of California and are underlain by Precambrian gneiss, Pre-Tertiary metavolcanic and metasedimentary rocks, and Tertiary volcanic and non-marine clastic rocks. Low-grade gold-silver resources may be present in hydrothermally altered gneiss in the upper plate and altered schist in the lower plate of the Chocolate Mountain thrust fault. The thrust fault is exposed in the study areas for about 3.5 miles west and 5 miles east of Indian Pass. Mineralized zones in the thrust plates were not discovered until 1983. Earlier prospecting explored areas containing minor copper carbonate occurrences in schist and sedimentary and volcanic rocks that are younger than the thrust. Twenty-three mines, prospects, and mineral occurrences inside the study areas and fourteen outs; de were examined for this study. These surficial copper occurrences have been prospected extensively in the study areas; large areas have been scraped, pitted, and trenched by bulldozers. However, they appear to be of limited economic significance. Slightly mineralized zones are in the northwest part of the Indian Pass study area where granite contacts sedimentary and volcanic rocks.

Jan 1, 1986

By A. R. T. Denues, A. P. Rowles

"INTRODUCTION Summarized data developed by J. E. Crawshaw and E.J. Murphy, 4/of the Explosives Division of the Bureau of Mines, suggesting marked variations in oxygen condition in three permissible explosives, have been reported 5/. Such variation is of interest in other work, it having been shown, for example, that the oxygen condition may have marked effect upon the products 3/ and the propulsive strength 7/ of explosives. It seemed that a more detailed presentation and more usual statistical analysis of these data might be of considerable general interest and not complemented in the literature.This report presents both the original data developed by Crawshaw and Murphy and the results of a simplified but seemingly acceptable statistical analysis of these data. The logical ground for this analysis might seem somewhat questionable because of the lack of systematic information concerning the extent of errors in the analytical procedure but the data show that there are several cogent and seemingly unequivocal indications of real heterogeneity in the explosives."

Jun 1, 1942

To design an apparatus that advances the state of the art in gas content testing equipment. The goal of the design is to incorporate improvements in testing sensitivity/accuracy, durability, and ease of operation over existing equipment. It is also desirable for the new design to successfully perform gas content determinations of multiple chemical species from a rock sample.

Jan 1, 1999

By Anil Mahyera

This report present the results of a laboratory and field research program aimed at design and development of a torque-thrust controlled bolter with the capability to (1) predict the "quality of anchorage" attained while installing mechanical anchor roofbolts, and (2) improve the uniformity and tension levels achieved among a group of roofbolts. The prediction accuracy of the anchorage quality algorithm ranged from low to moderate because of the complexity and variability of the phenomena involved. The best roof support with mechanical anchor bolts was found to be achieved by simply installing them under ? proper torque-thrust control, and with ? a hardened washer under the bolthead. This procedure resulted in an improvement in uniformity of 3 times, along with an increase in mean tension levels of 75% over conventionally installed roofbolts.

Jan 1, 1983

By E. D. Gardner

This paper discusses prospecting for lode gold and lists the principal lags and. regulations pertaining to locating; lode claims on public lands. It is a preprint of a part of a bulletin being prepared by the United States Bureau o Mines entitled "Equipping, Developing and Operating Small Gold Mines". The increased interest in gold mining manifested during the past few years (1932-1935) bas stimulated prospecting. Many adventurers have taken to the field to search for now gold deposits. A. large percentage of them have had no previous experience in prospecting for lode gold; this paper has been written with the tope that it might assist these newcomers.

Jan 1, 1935

By J. C. Meeks, C. L. Klingman

An instrument that is sensitive , portable , safe , and low in cost was developed by the Bureau of Mines for detecting helium leaks by comparing the thermal conductivity and flow rate of the atmosphere around the suspected leak against a reference of helium- free air . A vacuum pump pulls the sample gas through a restriction and over thermistor elements , the combined electrical output of which is affected by thermal conductivity and flow rate of the sample gas . Tests showed that the battery - operated Helium Leak Detector was effective and rugged instrument that could be operated safely in explosive atmospheres . The instrument could also detect , but not identify , other gases such as methane , hydrogen , argon , carbon dioxide , and Freon 12 .

Jan 1, 1964

By George R. Schottler

The objective of this research is to find the extent of the range of applicability of previously developed statistical methods for determining grade and tonnage of ore to bedded uranium deposits. Uranium assays obtained from gamma-ray logs of exploratory drill holes are used to compute grade and tonnage of ore in the deposit by a standard polygonal method and by statistical analysis. The results obtained by the two methods are compared. The uranium-assay frequency distributions are shown to be lognormal and a simple transformation permits the use of standard normal curve statistics. The effects on the assay frequency distributions of stratified sampling, a required minimum mining thickness, and increased assay-interval length are investigated. The addition of low-grade mineralization to make up the required minimum mining thickness results in a distinct change in the skewness of the assay frequency distribution. Any statistical inference regarding grade-tonnage relationships that will be produced, using the minimum mining thickness, should be made on the basis of this "revised" assay frequency distribution.

Jan 1, 1965

By Thomas C. Denton

ALL of the 45 political divisions of Africa were accessible to non-Communist world industry and commerce throughout 1964, although in some of them revolt and political attitudes presented problems. The position of the continent as a whole for mineral and mineral fuel resources, production, and oversea exports continued to improve. At yearend, significant quantities of a greater number of mineral commodities vital to industry and agriculture were being produced than in any other continent. This statement excludes Communist areas on other continents but might well hold true even if such areas were included. Deriving from its exceptionally diversified production, Africa furnished overseas industrialized countries as a w ole a greater variety of key mineral commodities than any other area. In addition, the value of mineral imports from Africa into the United Kingdom and continental non-Communist Europe probably exceeded the value of such imports from any other area if gold is included and mineral fuels excluded.

Jan 1, 1966

By Henry M. Harris, John E. Kelley, Thomas D. Roberts

A penetrometer apparatus for measuring viscosity of glass at temperatures up to 1,450 ° C was developed for use in establishing the viscosity coefficients required for high- temperature forming of ceramic materials . The major advantage of the method is that it can be used with samples of almost any shape or size without the necessity of forming or measuring shapes to close dimensional tolerances . Also , it has proved accurate in the range of 106 to 109 poises , a gap between the normal limits of other methods . The device , which operates on a single penetrometer principle , was used to determine the absolute viscosity coefficient of substances in centimeter - gram- second units of poises instead of relative penetration - rate units as with other penetrometers . Penetration of the viscous sample was sensed with a linear , variable differential transformer . The output of this transformer was recorded versus time , and the penetration rate was used in calculating the viscosity coefficient . The general equation relating penetration rate and viscosity coefficient was found to be 11 = F ( ln L/a 0.72 ) 2 π UL · where is the viscosity coefficient in poises , F is the penetrator load in dynes , L is the penetration depth in centimeters, a is the penetrator radius in centimeters and U is the penetration rate in centimeters per second . The penetrometer was tested using a standard viscosity sample of sodalime - silica glass obtained from the National Bureau of Standards ( NBS ) . Values obtained at several temperatures all agreed within 10 percent with comparable data calculated from the Fulcher equation derived by NBS for this glass . Equivalent accuracy was obtained with other glasses used to evaluate the apparatus .

Jan 1, 1964

By Lloyd A. Morley

Two mine electrical power system simulations are presented. The first is a batch processed procedure capable of modeling a single mining machine consisting of a number of motors operating under various loads. These loads are the mechanical torque loads present at the motor shaft. The second simulation is a more flexible tool for modeling entire mine electrical power systems~ Detailed analyses of bus voltages, transmission-line power flows, and machine behavior are possible. This simulation operates interactively and the power system is configured as the user responds to program generated questions and requests. Development of the theory behind the programming, as well as detailed explanations of the models, is presented. Examples are provided to demonstrate simulation capabilities.

Jan 1, 1978

By Lloyd Williams

1. The investigation shows that the Sewanee bed is the only bed of major importance in Marion County, 97 percent of the coal mined in the county having come from this bed. There are coal reserves in minor quantity in the Battle Creek bed, and production from this bed depends on a few small truck mines. The Richland bed, or Lower Sewanee, has been mined in the past, but no coal has been produced from it in late years. There are no production records of any other beds in the county, although same coal has been produced from them. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and on 1,800 tons per acre-foot of coal in place, are estimated to be 61 million short tons as of January 1, 1953. Of this total, 55 million short tons is in beds 28 inches and more thick. Areas in each bed were omitted from the estimate where available data relative to the bed characteristics are too meager to permit making an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1955

By J. F. Barkley

At the request of several Federal agencies, tests were conducted on a relatively recent type of anthracite -burning equipment named the Anthratube. This device, rated at 130,000 B.t .u. per hour, was designed to burn Pea-size anthracite automatically for steam or hot-water house heating and for domes-tic hot -water supply. ACKNOWLEDGMENTS The helpful cooperation of the Anthracite Institute and the manufacturers of the equipment, Axeman-Anderson Co., Williamsport, Pa., is gratefully acknowledged.

Jan 1, 1953

By W. T. Benson

Peacetime production of mercury in the United States is controlled by world mercury prices, with significant lags to be expected between price increases or decreases and resultant increased or decreased production. Twenty-four mercury-bearing mines and prospects in widely separated districts in western and central Nevada and one property on the Nevada-Oregon border were examined and sampled. The purpose of the project was to determine if some of the properties warranted more extensive exploration work to obtain information on possible reserves of commercial-and sub-commercial-grade ores. The investigation of mercury deposits in Nevada was sufficiently widespread and indicated several areas of interest in the State that merit further exploration work.

Jan 1, 1956

By R. Vernon Helm

Four tables listing values for the various physical properties of those sulfur compounds most likely to occur in petroleum and petroleum products are given herein. The data necessary to bring the first compilation2/ in this subject up to date are given in table I -Revised and Additional Data, which includes boiling points, refractive indices, densities, and freezing points. Tables 11-, III, and IV are published for the first time and include refractive indices for the F, C, and G' lines of hydrogen and the helium D:3 line; surface tensions and viscosities, and refractivity intercepts, specific dispersions, specific refractions, and parachors. The need for information concerning the sulfur compounds in petroleum is becoming-more urgent because of the necessity of refining larger quantities of high-sulfur crude oil to meet the rising demand for petroleum products. For a number of years the Bureau of Mines has been engaged in research to make available more information concerning the properties of the sulfur compounds in petroleum. The petroleum industry has recognized the value of such studies, and as a result the American Petroleum Institute has established Research Project 48A to study sulfur compounds. The investigations under this Project are to be done in Bureau of Mines laboratories as a cooperative project in connection with the work already started.

Jan 1, 1949

By Edward E. Johnson

The U.S. economy boomed in 1965, completing its fifth consecutive year of expansion. Although the advance was somewhat irregular, previous records for production, sales, employment, and income were topped. During the first few months of 1965, as the economy recovered from the depressing effects of the automobile strikes of late 1964, increases were unusually large. The gains moderated in early spring, but were stimulated at midyear by sharply rising capital outlays, excise tax cuts, in? creased Social Security payments, and accelerated Viet-Nam defense expenditures. Gross national product (GNP) in cur-rent dollars rose $49.5 billion or 7.8 percent, to a total of S681.2 billion. In constant dollars (effects of price changes eliminated), GNP increased 5.9 percent, a rate considerably higher than the historical postwar annual average growth of 3.5 per-cent. Demand increased in most final markets and was especially strong for business fixed investment and consumption expenditures. With the exception of construction, most of the increases in GNP were real, since prices increased less than 2 percent.

Jan 1, 1966

By Neal M. Muir, Robert S. Sanford, Bruce I. Thomas

"INTRODUCTION The presence of the zinc-lead-copper deposits an the north slope of Mount Eielson, Mount McKinley National Park, Alaska, has been known for many years. The deposits were examined by J. C. Reed, a geologist of the United States Geological Survey during the summer of 1931. In the summer of 1943 the authors and Clyde Wahrhaftig, a geologist of the Geological Survey, examined the deposits.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the and that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual investigative work, and prepares the final report. The Metallurgical Branch, Oliver C. Ralston, chief, analyzes samples and performs beneficiation tests.Particular acknowledgment is due to Heine Kenworthy, who conducted the beneficiation tests under the supervision of C. Travis Anderson; to Clyde Wahrahaftig of the Geological Survey, who completed the Geologic and topographic maps, to Grant Pearson of the National Park Service; and to O. M. Grant and Mrs. Frank McGarvoy for their assistance during the examination."

Nov 1, 1947

By W. W. Adams

"The fifth annual National Safety Competition conducted by the United States Bureau of Mines to determine the best safety records at mines and quarries during the calendar year 1929 has been concluded, and the general results of the contest are presented herewith. To the winner in each of the five groups into which the contestants were divided there has been awarded the bronze trophy 'Sentinels of. Safety,' donated by the Explosives Engineer magazine. The trophy for bituminous coal mines was won by a mine in Alabama; that for metal mines by an iron-ore mine in Michigan; that for nonmetallic mineral mines by a salt mine in New York; that for quarries and open-cut mines went to a limestone quarry in Michigan;. the trophy provided for anthracite mines was, of course, won by a mine in Pennsylvania, as all of the anthracite mines participating in the contest are situated in that State.Winners of the trophies were selected by a committee of sward in accordance with rules governing the contest and on the basis of accident records furnished by the various companies to the Bureau of Mines. These records were summarized by the bureau and the results submitted to the committee. Members of the committee are W. H. Cameron, managing director of the National Safety Council. William Green, president of the American Federation of Labor; James F. Callbreath, secretary of the American Mining Congress; T. T. Read, Vinton professor of mining of Columbia University and editor of 'Mining and Metallurgy'; C. B. Huntress, executive secretary of the National Coal Association; A. J., Curtis, assistant to the general manager of the Portland Cement Association; A. T. Goldbeck, director of the engineering bureau of the National Crushed Stone Association.Thirty-four States were represented in the l29 contest. Among the plants which participated were 68 bituminous coal mines, 29 anthracite mines, 54 metal mines, 19 nonmetallic mineral mines, all of the foregoing being underground mines, and 141 quarries or open-cut mines. A total of 106,533,006 man-hours of work was reported by all of the companies. Accidents during the year numbered 7,008 and represented a period of disability equal to 986,306 man-days. Hence the accident-severity rate for all plants combined represented 9.3 man-days of disability for each thousand man-hours of exposure to hazard. Similarly, the combined accident-frequency rate for all plants showed that 66.3 accidents occurred for every million man-hours of exposure to hazard. Both of these rates indicated an improvement over the combined rates for all plants in the previous year's contest. The reduction in the accident-severity rate centered chiefly in the metal mine group, though all except the quarry and open-cut mine group shared in the reduction; the improvement in the accident-frequency rate was in all croups except anthracite and metal, the rate for the former having increased while that of the latter remained unchanged."

May 1, 1930

By C. C. Clark

This report presents the results of tests conducted by the U.S. Bureau of Mines to determine the transport characteristics of highly concentrated paste backfill mixes made from dewatered total mine tailings. The slurry concentrations of the mixes were all above 78 pct by weight with slumps ranging from 6.4 to 16.5 cm (2.5 to 6.5 in). Laboratory material property tests and full-scale pumping tests were conducted using pipe diameters of 102, 128, and 154 mm (4, 5, and 6 in) and a positive-displacement pump. The results indicated that the tested backfill mixes can be successfully transported as a stiff paste and identified the influence of and the interaction among the various mix and system variables.

Jan 1, 2010

By J. Sammarco

Proper illumination is critical to a miner?s ability to detect hazards in underground mines. Moving hazards are often located in the miner?s peripheral field-of-view, while slip/trip/ fall hazards are often located in the forward field-of-view. The objective of the research described in this paper was to determine if light-emitting diodes (LEDs) improve visual performance as compared to traditional incandescent (INC) cap lamps. The research presented focuses on comparative studies of a National Institute for Occupational Safety and Health (NIOSH) prototype LED, a commercial LED and an INC camp lamp. Thirty subjects participated in these studies, with ten subjects in each of the following age groups: 18 to 25 years, 40 to 50 years and 51+ years old. Visual per­formance was quantified by the subjects? speed and accuracy in detecting hazards, while visual performance for disability glare was quantified by the use of contrast sensitivity tests. Results suggest that LEDs with a visible spectrum containing a higher concentration of the shorter wavelengths can enable visual performance improvements with respect to disability glare, the detection of moving hazards in the peripheral field-of-view and the detection of floor hazards in the forward field-of-view. The NIOSH prototype LED cap lamp provided the best visual performance improvements for the older age groups in every test.

Jan 1, 2009