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By Hal H. Engel

This publication was written in response to numerous requests for information about the Federal Bureau of Mines' "Demonstrated Lecture on Flame Propagation and Permissible and Explosion-Proof Electrical Equipment." The requests came principally from: (1) Persons wanting to know more about the demonstration before requesting it for groups they represented; (2) persons wishing advance information to help publicize a meeting where the demonstration was to be given; and (3) members of audiences desiring something to help them remember the salient points, facts, and figures presented during the lecture and demonstration. The purpose of the demonstration that accompanies the lecture is to show: (1) Variations in flame speed and pressure at various percentages of flammable gas within the flammable range; (2) effect of flame speed on the "pressure piling" within the area confining the mixture; and (3) the application of flame speed and pressure piling to the combustion of surrounding gas and to the design and maintenance of electrical equipment used in hazardous locations.

Jan 1, 1960

On December 16, the General Services Administration (GSA) suspended weekly sales of surplus silver from the national defense stockpile because Congress approved the Defense Appropriation Act, which contained an amendment to halt silver sales. The amendment, introduced by Senator James A. McClure (R., Idaho), prohibits sales for 6 months while the impact of the sales and alternative methods of disposal are evaluated. The GSA sold 2 million troy ounces since sales started October 14. 46.5 million troy ounces were authorized to be sold during this fiscal year and an additional 58.6 million troy ounces were authorized to be sold over the following two fiscal years. The stockpile held 139.5 million troy ounces of silver when sales began in October. Brush Wellman, Inc., a vertically integrated producer of beryllium products announced plans to modify its Delta, Utah beryllium concentrate processing facility to utilize beryllium concentrates containing as little as 7% beryllium oxide. The company plans to invest $2.5 million for this modification with completion expected in mid-1983. Implementation of this plan to consume lower grade beryllium minerals will significantly increase world reserves of beryllium concentrates.

Jan 1, 1981

By Richard F. Hewlett

The mining industry utilizes a vast store of knowledge, wisdom, and engineering talent in designing mining systems. However, the complexity of the required systems and the presence of numerous variables frequently necessitates raking important decisions without having adequate accurately detailed information. That many of the decisions made in the past were nearly correct, in the long run, is substantiated by the number of successful mining enterprises that exist in the world today. Subsequent to 1940, the disciplines of operations research and systems engineering were developed. The disciplines have produced methods of providing better information to persons responsible for making decisions.

Jan 1, 1963

By E. J. Matson

This report covers the investigation of the MacArthur copper deposit and several adjacent claims in the Mason mining district; Lyon County, Nev. (fig. 1). As a part of the Bureau of Mines program of investigation and development of domestic mineral deposits, a project was begun first on the MacArthur claims. Work was done later on some adjacent claims in the immediate area, as shown by figure 2. Field work was begun by the Bureau of Mines on January 16, 1950, and completed on October 25, 1950. Eight diamond-drill holes were completed, for an aggregate of 3,414 linear feet, Analyses were made of' each drilling interval. The report includes a brief history of the district and a description of the deposits and of the work done by the Bureau of Mines.

Jan 1, 1952

By A. Sainato, S. J. Kravits, G. L. Finfinger

This Bureau of Mines report describes and compares the procedures, capital investments, and operating costs of rotary and in-hole motor drilling techniques used to drain methane gas from the Pittsburgh Coal- bed in an underground mine located in southwestern Pennsylvania. A timestudy was conducted during the drilling of each of two boreholes, and the data were collated to serve as a base for comparing drilling procedures and operating costs. Findings indicate that drilling with an in-hole motor offers four advantages over rotary drilling; namely, an increase in drilling productivity, fewer worker-hours required, ease of maintaining vertical and horizontal bit trajectory, and less expensive drilling cost per foot of borehole.

Jan 1, 1985

By Joseph Blake Smith

Coal resource data from published sources and company files were used by the Bureau of Mines to determine the location and extent of strippable coal reserves in Wyoming. Total strippable reserves of 23 billion tons were estimated in seven major coal areas. Seven large strip mining operations were active in 1969, and their production totaled 45 million tons of coal. Cutoffs used to define strippable reserves were (1) minimum coalbed thicknesses of 5 feet; (2) overburden-to-coal ratios of less than 10 cubic yards of over- burden per ton of coal; and (3) total overburden thicknesses of less than 120 feet, except where reserves occur in multiple beds or a single thick bed. Tertiary rocks along margins of the Powder River basin contain most of the strippable coal reserves in Wyoming. The Wyodak beds, ranging in combined thickness from 30 to 1.30 feet, crop out on the east flank of the basin and contain an estimated 19 billion tons of strippable subbituminous C-rank coals under less than 200 feet of overburden. Partings between these beds total less than 60 feet. The 100- to 200-foot-thick. Healy bed on the western flank of the basin and the 35-foot-thick School and 20-foot-thick Badger beds on the south also contain large strippable reserves. Elsewhere in Wyoming, strippable reserves. Elsewhere in Wyoming, strippable deposits are subbituminous coal of Late Cretaceous and Tertiary ages, mostly in the Hanna and Great Divide basins in the south-central portion of the State and in the Kemmerer-Hamms Fork region in the southwestern corner.

Jan 1, 1972

By Manuel Gomez

The mean and the standard deviation were used to describe general sulfur and ash populations as well as specific populations of these variables from one coal seam. Both the mean and the standard deviation were incorporated in the exploration process to determine the number of drill cores necessary for seam evaluation and to guide the sequential drilling plan. Probability regions were computed to establish a basis for predicting probable ranges of average sulfur and ash concentrations that may be expected upon continued or future drilling. A computerized plot program was utilized to interpolate sulfur and ash concentrations between grid points. The plot program, which is essentially a moving average technique, permits a rapid evaluation of sulfur, sulfur forms, and ash spatial distributions as a drilling program progresses sequentially. This information, in the form of contour plots, can be made available to both the mining engineer and the fuel technologist in advance of mining to outline reserves, to improve selective mining, and to anticipate preparation facilities.

Jan 1, 1972

By Wilbert J. Huff

The Explosives Division of the United States Bureau of Mines makes certain laboratory and field investigations that deal with explosions, explosives, ignition, and combustion, together with many related problems, such as the cause and prevention of fires, and certain fundamental scientific questions bearing upon the determination of the chemical and physical mechanisms underlying some of the important phenomena encountered. Its work on explosives has been particularly directed toward determination of the chemical and physical characteristics of explosives designed for use in coal mines and in a more limited way to those used in metal mines, tunnels, quarries, and other engineering operations. This testing is handled by two units of the Explosives Division, as follows:

Jan 1, 1937

By Richard J. Kline

This publication comprises tables listing friction loss for a flexible, spiral-reinforced circular ventilation tubing system. The tables were constructed with the following parameters: a friction factor of 62 X 10-10, 10-foot sections of tubing ranging in total length from 100 to 550 feet, air quantities ranging from 1,000 to 15,000 cfm, and one to four 90° bends in the tubing. The aim of this publication is to improve ventilation tubing analysis and to provide a method of proper fan selection.

Jan 1, 1971

By J. C. LaScola

Development of methanometers and anemometers for underground use in coal mines is reviewed. The first semicontinuous recording methanometer was developed in 1961 in West Germany. The Bureau of Mines developed an instrument using; pellesters that was a continuous recording methanometer. Expansion of freon gas created a vacuum which pulled the methane-air mixture through a tube to an electrically heated, catalyst-impregnated pellester where the mixture was burned. The National Coal Board of England developed a continuous recording methanometer based on the principle of the Davy flame safety lamp. A thermo-pile was used to sense the hurt output of the flame. Finally the Bureau of Mines improved its methanometer by eliminating the freon gas and using a diffuser head to a monitor methane-air mixtures. Development of recording anemometers proceeded from the use of a photo¬cell and light source to sense rotation of the Biram-type anemometer blades to the use of a Hall detector to sense, rotation by measurement of electromagnetic pulses.

Jan 1, 1969

By A. W. Deurbrouck

This Bureau of Mines report describes the washability characteristics of 14 coalbed samples collected in Wyoming. Such data is needed to evaluate the quality of the coals of the West where most of our low-sulfur-content coal reserves are found. Of the 14 samples included in this report 13 had a total sulfur content of 1.1 percent or less. All of the samples contained low per¬centages of ash or could be readily washed to a desirable ash level with minimal loss of yield. The coals ranged in rank from high-volatile B bituminous to subbituminous C, although 10 of the samples were high-volatile C bituminous. The coalbeds varied in thickness from 4.5 to an unknown thickness greater than 67.5 feet.

Jan 1, 1971

By M. J. Kovalik

The effect of oxidation by air at temperatures ranging from 200° to 390° C on the change of chemical and physical properties of Pittsburgh-bed coal was studied as a function of processing time and temperature. The goal was to prepare a nonagglomerating fuel from a strongly coking coal for use in continuous carbonizing processes and in fixed-bed gasifiers. The oxidized coal was carbonized in a bench-scale apparatus, and the coke strength was evaluated in a Roga tumbler. Strength of the coke was progressively reduced with time of oxidation until the coking power of the coal was apparently destroyed. Time requirements to obtain an essentially nonagglomerating product were inversely related to processing temperature. Gaseous products released from the coal during oxidation reduced the yield of the desired nonagglomerating product, which decreased with time of oxidation at constant temperature and with increase in processing temperature at equal time. Oxidation at a temperature slightly above the lower limit of the plastic temperature range of Pittsburgh-bed coal was most effective because of the short processing time required and moderate processing losses.

Jan 1, 1963

By R. D. Saltsman

Under contract with the Federal Bureau of Mines, Bituminous Coal Research, Inc., performed a statistical study to find less expensive and time-consuming methods of monitoring the noncombustible content of coal mine dust. Calculations based on thermodynamic considerations verified the reasonableness of Federal rock-dusting requirements. The results of extensive sampling in southwestern Pennsylvania mines indicated that, at the 95-percent confidence level, the present system of sampling at 200-foot intervals may be replaced by sampling at 500-foot intervals, and that a 1-inch scoop floor sampler may replace the standard 6-inch scoop for floor sampling. Further field testing is recommended.

Jan 1, 1975

By Vernon O. Markworth

This report contains the results of tests performed on three large diesel engines to determine their ability to meet selected criteria of the Mining Enforcement and Safety Administration Regulations for equipment used in gassy, non-coal mines. Study efforts were first directed toward determining the types of equipment expected to be used in underground oil shale mines. Three typical engines in the 800-1200 horsepower range were then selected for testing. Intake flame arresters, exhaust scrubbers, and water jacketed exhaust system were designed and built for each engine. During testing, each engine was evaluated for its gaseous emissions output, adequacy of the exhaust gas cooling system, ability to withstand internal explosions, and adequacy of the flame arresters. Surface temperatures of the engine and exhaust cooling system were determined under full load operation.

Jan 1, 1978

By E. Chin

Bangladesh, whose population probably passed 100 million by yearend, remained one of the poorest countries in the world, with a per capita gross domestic product (GDP) of $126.2 Its only economically significant mineral production was natural gas. A few other minerals or mineral-based commodities were also produced, generally for local consumption. These included cement, clays, nitrogenous fertilizers, limestone, salt, steel, and pilot plant production of ilmenite and rutile. Exploration for oil was a continuing quest, which was hindered by a lack of funding and a hesitancy on the part of foreign petroleum companies to make long-term or expensive exploration commitments. PODUCTION AND TRADE Production of natural gas continued to increase as more use was being made of the abundant gas reserves variously put at between 7 and 16 trillion cubic feet. The main consumers were nitrogenous fertilizer producers and electric powerplants, but other industries were converting to natural gas from imported coal or fuel oil wherever possible.

Jan 1, 1986

By R. C. Corey

Anticipating the need for convenient, economical, and safe means for disposing of combustible wastes contaminated with low-level activity, in connection with private and institutional uses of radioisotopes, the Atomic Energy Commission (AEC) has provided the Bureau of Mines with funds to develop an incinerator for this purpose. A prototype incinerator, designated hereafter as BOMAEC-30, was designed, constructed, and tested, based on fundamental and applied research investigations of the combustion characteristics of rubbish and sawdust, which will comprise the bulk of contaminated wastes. No radioisotopes were used in the tests; the objective was to remove as much particulate matter from the products of combustion as possible. The prototype unit was designed to burn 30 pounds per hour, using 100 percent over fire air admitted tangentially in an all-metal, cylindrical combustion chamber. The gas-cleaning system consisted of special fabric bags and absolute filters.

Jan 1, 1962

Synthetic dawsonite [NaAl(OH)2C03] has been prepared with crystallinity similar to that of dawsonite found in oil shale deposits of the Piceance Creek area of Colorado. Optimum experimental conditions were as follows: Na/Al atomic ratio, 43; temperature, 175° to 200° C; pCO2, 15 psig; and reaction time 5 hr. Chemical and spectrographic analysis revealed that the synthetic dawsonite was of high purity and Has essentially stoichwmetric. Similarity of the synthetic to natural dawsonite, demonstrated by X-ray diffraction, infrared spectrophotometry, and electron microscopy, suggests its suitability as a standard.

Jan 1, 1972

By R. Hogg

"The problems of sampling particulate materials, and of characterizing the distributions of particle size and composition are reviewed. Requirements for sampling from comminution systems are discussed and a simple formula is presented for estimating the minimum sample size needed. The limitations and errors associated with the techniques available for particle size analysis are evaluated and guidelines are suggested for the selection of appropriate methods. The use of microscopic and macroscopic approaches to the characterization of particle composition are discussed.INTRODUCTIONComminution is a process of particle size reduction in which the goal is to produce a material with a specified particle size distribution from a coarser feed. In mineral processing applications, the product size distribution is often qf secondary importance to the extent to which individual mineral grams can be liberated from one another. However, due to poor understanding of the nature of the liberation process and the lack of reliable procedures for characterizing it, the actual specification is normally in terms of particle size.Particle size distribution can be regarded as the fundamental characteristic of a particulate system. The distributions of particle shape and composition among the various particle sizes present are often sufficient to define the bulk properties and behavior of the system. Description of the distributions of size; shape and composition of the different phases which may exist within individual particles is necessary to complete the picture and is especially important for predicting liberation etc., in comminution processes. It is quite obvious that · the complete characterization of real particulate systems is a formidable, if not .impossible task. Practical characterization procedures should involve ·evaluation of those characteristics which are deemed to be important and which can be measured. In comminution systems, this should ideally include the particle size distribution, the size-by-size distributions of particle composition, and as much information as can be acquired on the internal composition and structure of individual particles. In most cases, of course, we fall far short of even this rather limited goal."

Jan 1, 1988

By David K. Denton

There are no active mines in the Mt. Eddy RARE II area. Chromite, gold, and stone prospects were examined. The RARE II area contains no identified mineral resources; however, a sample of a 260 ton occurrence contained 38.1 percent chromium oxide (Cr203) at the Ratero Prospect (fig. 1, no. 3), which has low potential for chromium resources. The Johnson Mine (fig. 1, no. 6) produced a small unrecorded amount of chromite during World War IT, but only a low potential exists for chromium resources. A low potential exists for gold resources at the Half Century Prospect (fig. 1, no. 2). At a borrow pit northwest of the study area (fig. 1, no. 1), sheared serpentinite is quarried for road metal; similar rock occurs in the RARE II area, but better material is more readily available elsewhere. Sand and gravel occurrences are too inaccessible and distant from markets to be considered resources. Mineral fuels and geothermal resources were not evaluated during this Bureau of Mines study. There currently are three unpatented lode mining claims in the study area. INTRODUCTION The Mt. Eddy RARE II area is 7 air-mi west of Mt. Shasta City, California, and straddles the Siskiyou-Trinity county line. The roadless area includes 7,200 acres of rugged, glacially carved, ridges and drainages which comprise Mt. Eddy. Elevations vary from 6,000 ft along the North Fork Sacramento River to 9,025 ft at the summit of Mt. Eddy. The area is covered with conifer forest below 8,000 ft elevation.

Jan 1, 1983

By J. E. Pahlman

One of the goals of the Bureau of Mines is to develop metallurgical pro-cesses that conserve energy and/or that take advantage of abundant domestic energy sources. Western lignites and subbituminous coals can be used for firing pellet induration and metallization furnaces. However, the refractory linings of these furnaces must be able to withstand attack from corrosive alkali metal oxides present in the ash of many of the low-rank fossil fuels. The Bureau of Mines conducted dynamic and static slag tests on high-alumina and alumina-silica refractories to determine their resistance to lignite ash slags. The investigations showed that increased alkali content in the lignite ash caused increased corrosion and erosion of the tested refractories. The degree of corrosion decreased with increasing alumina content, with the 99-percent-alumina refractories having the highest resistance. In general, the matrix phase was attacked preferentially to the alumina grains. Also, porosity reduction and tar impregnation enhanced the corrosion and erosion resistance. The 90-to 99-percent-alumina refractories are recommended for use as furnace linings in alkali slag environments.

Jan 1, 1979