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By A. C. Johnson

This report is one of a series being prepared by the Bureau of Mines on exploration, development, mining methods, and costs at various mines in the United States. It describes operations at the Black Rock mine, Wah Chang Mining Corp., Mono County, Calif. The purpose of these reports is to promote development and conservation of our mineral resources by disseminating technologic information on mining methods, practices, and costs. The Black Rock tungsten mine of the Wah Chang Mining Corp. is 33 miles north of Bishop, Calif., in the Benton Range, Mono County, Calif. The property was acquired in August 1950 and a well-planned program of exploration, development, and exploitation resulted in a good production record with low costs. Operations were halted in July 1957, about 6 months after suspension of the tungsten purchase program by the Federal Government.

Jan 1, 1960

By Martin A. Elliott

"INTRODUCTION During the recent war the Bureau of Mines was requested to obtain in¬formation on the temperature at which ammonium nitrate mixed with certa: contaminants would react rapidly. This information was desired in connection with an investigation of an explosion that had occurred during the evaporation, by air agitation, of volutions containing ammonium nitrate in which compressor oil that might have passed the filters was suspected of being a contaminant.During the course of this work it was found that mixtures of ammonium nitrate and zinc reacted rapidly at comparatively low temperatures: and since zinc could not positively be eliminated as a contaminant in the explosion in question, a series of tests was carried out, not only with mixtures of ammonium nitrate and compressor oil but also ammonium nitrate and zinc with and without oil. A few experiments were made with metals other than zinc.The investigation was not as extensive as might have been desired, owing to limitations -in time. The results are presented at this time in view of their current interest in connection with the Texas City disaster, in which a large quantity of ammonium nitrate detonated in the holds of two ships."

Mar 1, 1948

By T. F. Dumm, O. Trass, V. R. Koka, L. G. Austin

"The size distributions of carefully screened 2 size fractions of ground materials were determined using a Microtrac laser dif-fractometer. The size distributions were fitted to the empirical function P(x) = 1/[1 + (x50/x)1] where P(x) is cumulative mass fraction less than Microtrac size, x. The standard deviation of A for a 50 second test time was approximately 0.5, so that seventeen test times give a mean with an estimated error within t 0.25 (95% confidence level). Values of were 5.44, 4.82, 4.40 for a coal ground under different conditions, indicating statistically different shape distributions; the average value for mica was 2.91 owing to the high aspect ratio of the particles. The ratio of x50 to the geometric mean sieve size was 1.2 for the coal and 0.70 for mica.1 IntroductionKoka and Trass have presented evidence [1,2] that materials ground in the Szego mill [3] give different shapes depending on the milling conditions. The variations in shape were deduced qualitatively by viewing SEM photomicrographs of selected 1/2 screen fractions. This paper quantifies their observed differences in shape by using measurements of the size distributions of screen fractions examined in a laser diffractometer [4] (Microtrac, Model 7991). The basic concept is that particles of 'a given ""screen"" size will give a wider distribution of ""Microtrac"" size when the particles are flaky with high aspect ratios, and a narrower distribution when the particles approach the cubical and spherical geometries.2 TheoryAustin and Shah [5] have shown that coal screened within a 1. 1/2 upper-to-lower sieve size range will give rise to a much wider distribution of Microtrac size. They found that the screen interval of irregular fragments of comminuted coals or quartz gave Microtrac size distributions which could be described by the simple function"

Jan 1, 1988

By J. M. Singer

The objective of this investigation was to determine minimum air velocities and entrainment rates for coal and rock dust dispersion in wind tunnel experiments under conditions that simulate dispersion from surfaces in coal mines where airflows are induced by weak gas explosions. Dust deposits were bed-or ridge-shaped; particle sizes were 6 to 80 microns (cohesive deposits) or 100 to 150 microns (free-flowing deposits); and wind tunnels were 7.62 cm wide by 5.08 cm high by 300 cm long, and 2.4 m wide by 1.5 m high by 215 m long. The investigation showed that minimum air velocities (directed at mid-height) of separate, layered, or mixed piles of coal dust and rock dust were within the range 5 to 30 m/sec, independent of size of wind tunnel. This finding considerably facilitates scaling of data to mine-size passageways. Free-flowing deposits dispersed relatively slowly by single-particle detachment; cohesive dusts dispersed faster by the breaking and lifting of large clumps along weak failure flames; particle dispersion occurred in flight. Layered or mixed deposits of coal and rock dust did not disperse selectively. Semiempirical expressions were derived relating minimum air velocities and dispersion rates to dust-pile geometry, cohesion, porosity, and bulk density.

Jan 1, 1972

By J. Mutmansky, C. Lee

"The size distribution of coal mine dust is one of its most important characteristics because the particle size is known to govern the region of deposition of dust within the human respiratory tract. In addition, dust characteristics, particle settling rate, transportability of the dust and the efficiency of dust control measures are all affected by the particle size. As a result, particle size distribution of the airborne dust in a coal mine is a fundamental property that impacts on the health of underground workers.This paper deals with some basic findings on the size distribution of cool mine dust based upon the results of data collection in six underground coal mines using continuous miners. All airborne dust sampling was performed on development sections using eight stage cascade impactors and permissible 2. O l / min pumps. Samplers locations were fixed in the sections with respect to the continuous miner and roofbolter or with respect to the intake and return airways • Sampling times varied from 45 minutes to 6 hours , depending upon the dust concentration. The first topic of analysis was the test to determine whether the commonly used lognonnal distribution is valid when applied to airborne coal mine dust. Secondly, the conventional method of representing the· distribution using two parameters, the geometric mean and the geometric standard deviation, is questioned. Since almost all size data were found to show some degree of bimodality, the two parameter lognonnal distribution may not represent the total airborne coal mine dust size , quite adequately. Bimodal lognonnal distribution was tested to be a good approximation in the case with two modes in the size distribution.The final topic discussed in this paper is the 'locational variation of the airborne dust size distributions within the continuous mining section. The size distributions varied considerably at the different sampling locations with the continuous miner and roofbolter producing the coarser distributions. Fine size modes in the range of 2 to 4µ m including mostly respirable dust particles were present in almost all samples • Second dust generating sources such as the shuttle car movement were found to be major causes of high respirable dust concentrations in some cases ."

Jan 1, 1988

By Ronald A. Vary

This paper is one of a series prepared by the United States Bureau of Mines dealing with milling methods and costs. In view of the current revival of interest in gold mining, information dealing with practices and costs in the development of gold properties is apropos. Milling practice at a small gold property in the prospect stage is described where, with a small outlay for plant and equipment, development has been carried on for about 20 months on the proceeds of the mill operation with little additional expenditure. The paper shows about what may be expected as to costs at a small property operated under northern climatic conditions and with rigid economy throughout the plant.

Jan 1, 1931

By G. St John Perrott

"The United States Bureau of Mines is cooperating with the State of Utah and the City of Salt Lake in an investigation of methods of abating the smoke nuisance in Salt Lake City. In the course of this work samples of the atmosphere have been collected and analyzed in an attempt to determine the part played by sulphur dioxide or smelter gases in polluting the air at Salt Lake City.A fairly wide-spread opinion exists in Salt Lake City that the smelters contribute appreciably to the smoke nuisance. The gases discharged from the smelter stacks are believed (1) to float over the city in a heavy blanket which prevents the smoke from rising, and (2) to unite with the water vapor in the air to form corrosive fogs injurious to health and property.The first of these theories seems untenable. If the gas did not mix with air it would sink, owing to its heavier specific gravity, and form a blanket an the earth. Actually, the gas diffuses rapidly in air and any part reaching Salt Take must he thoroughly diluted. Perhaps sulphur dioxide in sufficient concentration might aid in fog formation. The more obvious nuisance, however, would be the injury to health and vegetation.The Garfield smelter is 16 miles west of the city, The Murray smelter 8 miles south, and the Midvale smelter 12 miles south. Under normal operating conditions, a relatively small amount of solid matter is discharged from these stacks. The toxic gaseous constituent of the discharge is sulphur dioxide, it is being discharged from the smelters the year round. If they are a factor in the city's smoke problem, the concentration of this gas in the air of the city should be appreciable and should increase toward the smelters, the con centration being highest with a south or a west wind."

May 1, 1920

By W. T. Culler

"The ""rate-of-preduotion curve"" described in the revised Treasury Manual* was devised by the author in May, 1920, and since that time has been use by the oil and gas valuation section of the Treasury Department in determining the rate of production of wells for purposes of taxation. This curve is most useful for estimating the future production of a well, or group of wells, of known daily settled production, where future-production curves and tables based on yearly production records are available. It also provides a means for determining the past year's production of a well of known daily settled production, or conversely, the estimated production on any day for a well of known yearly production.The rate-of-production curve is auxiliary to the production decline curve and is derived from it in estimating the future production of a tract, a production decline curve formed from the records of the tract itself should be used. If such records are not available, and there is no information which leads to the belief that the average production decline of the wells in this tract differs from the average for the pool or district, an average curve for the pool or district may be used.The accompanying chart illustrates a typical rate-of-production curve, with the yearly production decline curve from which it is derived. The production decline curve shown is for an average well in the Augusta district, Butler County, Kansas, and has been constructed from the tables given on page 128 of the revised Treasury Manual.The ordinate (vertical scale on the chart) of any point on a yearly production decline curve represents the production of the well during the year previous to the date shown by the abscissa (horizontal scale). For example, the chart shows that an average well, which produced 100,000 barrels of oil in 1915. produced 92,000 barrels in the year previous to January 19, 1916, produced 53,300 barrels in the year previous to June 1, 1916; produced 49,000 barrels in the year previous to July 1, 1916, 27,000 barrels in 1916, and 10,000 barrels in 1917."

Oct 1, 1921

By Philip E. Sanker

The Bureau of Mines conducted small-scale batch and semicontinuous tests on the reduction of zinc sulfide with iron according to the reaction ZnS + Fe ? FeS + Zn to determine reaction kinetics in the temperature range 1,000° to 1,400° C and to investigate the potential use of a scrap iron reductant. Batch tests indicated that a temperature of at least 1,300° C with a 1:1 mole ratio of Fe to ZnS is needed for good zinc recovery. Semicontinuous tests were conducted, using four zinc concentrate samples, containing various percentages of copper, cadmium, and lead, which were reacted with iron and iron contaminated with iron oxide and tin in an externally heated graphite furnace. Analysis of the zinc metal and FeS matte reaction products showed cadmium to be entirely in the zinc metal, copper to be in the FeS matte, and lead to be about 60 pct in the zinc metal and 40 pct in the matte. Tin reported to the matte, and none was detected above the O.OS-pct level in the zinc. Sulfur dioxide was not detected in the offgas when up to 20 pct of the iron was replaced by Fe203.

Jan 1, 1976

By J. A. McAllister

In the course of a study of domestic Manganese resources, 2-ton representative samples of ore were taken by Bureau of Mines' engineers from the Payday claim, Weber County, and the Newcomb-claims, Rich County, Utah. The Payday No. 1 deposit is situated 13 miles northeast of Huntsville, Weber County, Utah. The manganese ore is a. replacement deposit in limestone and consists of manganese oxides imbedded 'in clay and also as the cementing agent consolidating small pebbles and pieces of quartz and limestone.

Jan 1, 1949

By G. A. Apell

The presence of considerable mineralization at the surface together with other favorable conditions suggested inclusion of the Nigger Jim diggings area in a comprehensive study of shallow lead deposits in southwestern Wisconsin. The area, which was the site of considerable shallow development some 60 to 70 years ago, offered the possibility of substantial quantities of lead at near-surface horizons. The investigation included completion of 30 churn-drill holes totaling 1,808 feet of drilling, 2 diamond-drill holes totaling 164.5 feet of drilling, and 25 feet of test pitting in two excavations. The degree of mineralization was determined in an area l,500 feet long and 150 to 300 feet wide along a mineralized trend that has not been investigated beyond the limits of the zone drilled by the Bureau of Mines.

Jan 1, 1948

By G. S. Price

This paper, which describes the milling practice at the Page concentrator of the Federal Mining and Smelting Co., is one of a series being prepared by the Bureau of Mines. The Page mine and mill are located on Silver Creek, 3 miles west of Kellogg, Idaho, and 1 mile south of United States Highway No. 10. Supplies and concentrates are hauled by truck over an automobile road which connects Highway No. 10 with the property. The concentrator has capacity to treat 300 tons of ore per day and utilizes all-flotation methods of treatment. Power is supplied from the main line of the Washington Water Power Co. which runs from Spokane, Wash., to Kellogg, Idaho. Water is obtained from the mine and also from a well which is situated 1 mile distant from the concentrator and about 600 feet in elevation below the concentrator.

Jan 1, 1932

By John C. Franklin

A radon survey was made at five different locations in the Twilight mine near Uravan, Colo., to determine chances in radon concentrations in an inactive mine. Data were taken with a continuous monitor set for 1-minute count periods and readings were taken 24 hours a day for 9 days. The 12 readings per station each hour accurately showed how t w radon concentration varied during the day. From the data collected from the intake portal to station 4, the average radon emanation rate was estimated at 18 picocuries per second per square foot (pCi/sec/ft3). A daily cycle in radon concentration was detected that apparently was related to barometric pressure change.

Jan 1, 1976

One of the major unknowns in the use of iron and copper is the quantity of various low level impurities, particularly hydrogen, that may be introduced during the deoxidizing process prior to casting. Introduction of hydrogen results in the embrittlement of components made from these metals. In addition, hydrogen bubbles in castings of copper result in the formation of blisters and swelling of the casting. During the last year, a significant effort has been made at the University of Missouri-Rolla to understand the permeation of hydrogen in galvanized automotive steel components and the hydrogen absorption during the electrodeposition of copper. The galvanized steel components consisted of automotive upholstery clips, seat belt holders and brake clips. Although the process of galvanization protects the steel from corrosion the process invariably causes the steel to pick up enough hydrogen to make it susceptible to brittle fracture.

Jan 1, 1992

By G. A. Apell

Completion of 18 churn-drill holes totaling 2,218 feet and 3 diamond-drill holes aggregating 421.5 feet of drilling in the M.C. mine area, near Truman, Wis., provided information indicating the existence and trend of a zone of zinc mineralization extending for 1,000 feet west of the old M. C. shaft.

Jan 1, 1949

By Steven W. Schmauch

In 1985, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied 27,930 acres of the 52,000 acre East Fork High Rock Canyon Wilderness Study Area, CA-020-914/NV-020-006A, in order to evaluate the mineral resources. The study area is located in Humboldt and Washoe Counties, NV, about 45 miles east of Cedarville, CA. Bureau of Mines personnel reviewed pertinent literature and county mining records and examined prospects or mineralized areas. There are no organized mining districts and no historical or active claims in the study area; one small pit lies in the southwest corner of the study area. Based on published literature, sample results and field observations, there are no recognized mineral, geothermal, or fossil fuel resources. Epithermal mineralization indicators are not present or exposed. Sand and gravel deposits in the study area are not likely to be developed as other deposits are closer to market areas.

Jan 1, 1986

By Louis A. Panek

The practice of roof bolting or rock bolting to stabilize rock surrounding underground excavations has increased tremendously within a few years. This widespread application has led to many questions concerning the mechanics of bolting and has pointed up the need for a quantitative method of designing bolting systems. To answer these questions a research program was initiated to determine the principles of roof bolting. The first problem chosen for investigation was the use of bolts to reinforce bedded roof, since the great majority of bolts are used under these conditions. The attack employed is a combination of theoretical and experimental stress analysis. Centrifugal testing of models was chosen as the experimental method because it is particularly suited to the study of stratified roof. This report describes the models, the experimental method, and the model-prototype relations. By using dimensional analysis, a general expression for a roof-bolting design formula in terms of the structural variables has been obtained. Certain model-prototype similarity requirements have been relaxed, thereby minimizing the number of variables to be studied and extending the applicability of quantitative test data to a large class of full size structures.

Jan 1, 1956

By Philip C. Good

The Bureau of Mines investigated the feasibility of utilizing low-grade phosphatic shale as a feed for phosphoric acid production. Present practice in the phosphate mining operations of southeastern Idaho is to remove and either stockpile or waste low-grade phosphatic shales as the high-grade phosphate beds are selectively mined. Acid digestion studies were performed on uncalcined shale and on shale calcined to remove free carbon to determine phosphoric acid quality, yield, and amenability to filtration. The untreated shale, containing 21.4 pct P205, was digested with sulfuric acid in a single-tank reactor to yield phosporic acid and gypsum residue. Although 96 pct P205 recovery was attained in digesting uncalcined shale, only the calcined product gave satisfactory filtration rates. Calcined shale yielded phosphoric acid recovery of about 93 pct of the contained P205. It was higher in impurities than commercially prepared acid derived from high-grade western phosphate rock. An acid filtration rate of 745 lb P205/ft2/day was attained. This value is lower than the rate of 900 lb P205/ft that is generally considered to be acceptable in industrial production of phosphoric acid from high-grade phosphate rock.

Jan 1, 1981

By Thomas E. Green

A solvent extraction procedure using 8-hydroxyquinoline and chloroform was investigated by the Bureau of Mines as a preconcentration technique for the determination of aluminum, calcium, cobalt, copper, iron, lead, magnesium, manganese, nickel, and zinc in large samples of high purity tungsten. X-ray spectrographic and atomic absorption methods were used to determine the trace metals after preconcentration. The presence of 10 grams of tungsten had a pronounced effect on the distribution of 8-hydroxyquinoline between the aqueous and chloroform phases. This change in the 8-hydroxyquinoline distribution in turn had an adverse effect on the extraction of the trace metals. Extraction efficiencies can also be adversely affected by an increase in the quantity of extractable metals present, as shown by radiotracer tests using 65Zn. Excess 8-hydroxyquinoline in the extracts did not interfere with the determination -of the serious interference in the combined ion exchange paper--X-ray spectrographic method. Although preconcentration by 8-hydroxyquinoline extraction was found to be partially successful, other preconcentrationn methods based on ion exchange and dithizone extraction were found to be superior.

Jan 1, 1968

By N. N. Moebs

The atmosphere in part of an air-sealed coal mine was monitored continuously through a drill hole for oxygen content to determine the effectiveness of sealing a mine against the entrance of air and the major force that caused the phenomenon of mine breathing through the overburden. The differential pressure across the seal and the barometric pressure on the outside also were recorded. A general correlation, obtained between the oxygen level, differential pressure, and barometric pressure, indicates that changes in air pressure are the cause for periodic replenishment of the oxygen in the mine. Mine effluent quality was determined by conditions in many sections of the mine and could not be related to the oxygen level at the drill hole.

Jan 1, 1972