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By Clarence O. Babcock

Model pillars of limestone, marble, sandstone, and granite having length to diameter ratios of 3:1, 2:1, 1:1, and 0.5:1 were broken in axial compression to determine whether lateral end constraint affected the breaking strength. Steel rings bonded to the ends of the model pillars with epoxy provided, during the loading cycle, a lateral end constraint of about 17 to 30 percent of the average axial stress. The effect of this constraint was to increase the breaking strength of the rock as compared to cylindrical pillars without constraint. The percentage increase in breaking strength varied with rock type and increased as the length to diameter ratio decreased. The maximum increase in breaking strength was 35 percent for marble pillars having a length to diameter ratio of 0.5:1. A theory was developed which relates the expected constraint to the physical properties of the ring and rock.

Jan 1, 1968

By John I. Kasteler

The Rambler mine is in the Douglas mining district, Albany County, Wyo. (fig. 1). The property was first operated about 1870 for gold found in the outcrop of a leached ore body. Copper and metals of the platinum group were discovered, in 1900, or soon thereafter, and intermittent mining was done until 1918, when a fire destroyed the surface plant, and the underground workings caved. The mine has since been idle. The Bureau of Mines conducted a development project on the property from October 1942 to October 1943, with a recess period between November 1942 and August 1943. Ten diamond drill holes, totaling 1,859 linear feet, were drilled on the property (fig. 2). The mine dump was sampled after preparation with a bulldozer. Assay determination and spectrographic analyses disclosed small quantities of copper and metals of the platinum group in the samples. Determinations were made on 11 samples from the diamond drill holes and 23 samples from the mine dump. The assay results and spectrographic analyses are given in tables 1 and 2. The logs of the diamond drill holes are given in an appendix to this report.

Jan 1, 1949

By A. D. Garman

The mining ordinance of Costa Rica dates from 1830. In spite of the numerous attempts to enact a new ordinance , it has been so much amended and reamended during the hundred years of its existence either expressly or , more often , by implication , and sometimes by Executive Decrees of which the validity has been called in question - that in most cases no one but a lawyer thoroughly conversant with Costa Rican mining practice could properly advise with reference to it . The present attempt at a digest of these laws is based on the 1929 edition of Bolandi and Johanning - the only source available in Washington . Apparently this edition has no official character , and the editors themselves often made surmises although one would think that definite facts would be available in Costa Rica where it was published .

Jul 1, 1930

By G. W. Birge

As a part of its overall program of coal carbonization, the Bureau of Mines is studying the coking properties of coals that may be used for metallurgical purposes. The objectives of this study were given in detail in a previous report.2/ The inherent suitability of coal for metallurgical use depends primarily on (1) chemical composition, (2) preparation characteristics, and (3) carbonization behavior. The first two factors, as well as the available reserves, are considered in selecting coals for carbonization tests. The selection of coal beds in Westmoreland County for coking tests was based, in part, on estimates of the coal reserves by Dowd,3/ who estimated the recoverable reserves in beds 28 inches or more thick, in thousands of tons, as follows: [ ]

Jan 1, 1957

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 S. L. May

Tantalum and columbium can be extracted from several of their ores or concentrates by chlorination procedures. Direct chlorination of high-grade minerals in the presence of carbon at temperatures between 500° and 800° C will extract up to 99 percent of the tantalum and columbium. Metallurgical beneficiation of low-grade source materials by carbothermic reduction produces a ferroalloy that is amenable to chlorination at a temperature of 500° C. Over 90 percent of the tantalum and columbium can be recovered.

Jan 1, 1965

By BUREAU OF MINES

A complete list of permissible mining equipment, rescue apparatus and gas masks tested prior to January 1, 1925, was published in Bureau of Mines Technical Paper 3761. The present list includes all equipment tested and approved by the Bureau, up to and including January 1, 1926, and supersedes the list issued as Serial 27202 in November, 1925. It covers electric air compressors, coal drills, mining machines, mine pumps, room hoists, switches, electric cap lamps, flame safety lamps, electric hand and trip lamps, flash lamp, methane indicators and detectors, blasting units, storage battery loco- motives, power trucks, self-contained oxygen breathing apparatus and gas masks. The system under which these devices were tested permits the manu- facturer, after his equipment has passed certain tests prescribed by the bureau, to mark his equipment with a seal showing that it has been "approv- ed" by the Bureau of Mines. The tests are designed to insure that the equipment has the minimum requirements for safety in use. The only object of the bureau in making such tests and publishing lists of permissible equipment is to safeguard the lives of workers and to help lessen the hazards of mining.

Feb 1, 1926

By S. A. Matthes

This Bureau of Mines report describes a system for the dissolution of metal and mineral samples using a microwave heat source. Samples and an acid mixture are placed in sealed polycarbonate vessels. The vessel contents are heated using microwaves, digested for 2 min, and quickly cooled. After the solution is brought to a final volume, the vessel contents are heated an additional 2 min in the microwave oven. Using this method, a slag, a feldspar, and a Ni-Cu alloy were dissolved and analyzed by atomic absorption spectroscopy. Values obtained for Na, K, Cu, Ni, Si, Mg, Mn, Ca, Al, and Fe agreed with certified values and had an average relative standard deviation of 1 pct. This system results in a significant savings in time and expense over traditional methods of sample dissolution, and is ideal for preparing solutions for analysis by atomic absorption, plasma optical emission, or X-ray spectroscopy.

Jan 1, 1983

By Robert C. Hickman

"INTRODUCTION The Big Four fault and the Sandy Creek fault, with several cross faults, traverse the Stalion-Curnel fluorspar prospect in a northeasterly direction. The Big Four mine, about three-quarters of a mile northeast of the prospect, is the only active mine in the immediate area.A resistivity survey was made of a portion of the prospect by the Division of Geophysical Exploration, Bureau of Mines, in May and June 1946. As a result of this survey, five holes were drilled by the Bureau of Mines during the period from October 8 to December 16, 1946. Two Longyear No. 12 Junior Straitline diamond drills were used for the work.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective more effective utilization of our mineral resources to the end 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 Division, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, Oliver C. Ralston, chief, analyzes samples and makes beneficiation tests.The project was under the supervision of Mitchell H. Kline, chief, Raleigh Branch, Mining Division."

Mar 1, 1948

By R. E. Head

"The microscopic work described below was engaged in primarily into ascertain the approximate proportions in which the copper sulphides existed in the ore examined, and by a comparison of the results obtained from a study of both head are tailing samples to supply data which might be of value in treating the ore by flotation. Incidentally, the physical characteristics and association of the sulphides were noted in order to determine the possible relation or bearing of these features on the present conditions of treatment. Since the copper in the ore occurred as three distinct sulphide minerals - chalcopyrite, chalcocite, and bornite each containing copper in different proportions, there appeared to be little or no possibility of obtaining the desired information by chemical methods of determination.Type of material examinedThe material examined was in the crushed condition and was said to be representative of the flotation feed or heads and the resulting tailing. No hand samples of the ore were examined nor any account taken of the physical condition and association of the minerals in place, because the possible value of the analytical results depended on conditions as they existed in the crushed ore. As the problems under consideration dealt only with the sulphide minerals, especially those of copper, the products from screen sizing were concentrated by hand panning and the gangue discarded. The concentrate obtained consisted almost entirely of the sulphide minerals, since the panning had been very carefully done. The object of this procedure was to obtain a sufficient quantity of high-grade sulphide material, from the sample of each screen size selected for examination, to permit its being so prepared for examination as to be representative of the physical characteristics exhibited by a large number of sulphide grains from each respective size, In the tests and investigations carried on by the company' treating the ore the following sizes had been used in tabulating data and basing conclusions:+48, +65, +100, +150, +200, and -200. These same sizes were used in the microscopic investigation, since the results obtained thereby could be most readily utilized for comparison with the results obtained in previous experimental work, together with deductions based on actual concentration of the ore on a commercial scale."

Jun 1, 1921

By H. S. Chiang, Zhao. Y. F., G. C. Sun, S. S. Peng

"Chiang; H. S. West Virginia UniversityPeng, S. S. West Virginia UniversitySun, G. C. West Virginia UniversityZhao, Y. F.West Virginia UniversityDust sampling was performed in two longwall faces working in two separate seams. Instantaneous dust samples were measured by RAH's. for various locations In the longwall faces. Preliminary analysis of the data shows that in addition to the shearer's haulage speed, there are four major factors that influence the airborne dust distribution in longwall face areas: locations with respect to the position of the shearer's cutting, hardness of the materials, characteristics of water spray, and roof conditions. This paper presents the effects of those four parameters in detail.INTRODUCTIONA research project was initiated in September 1983 to measure and construct .a dust distribution map for the longwall face. During the first year, airborne dust samplings were performed in two longwall panels located in northern and southern West Virginia and working in the Pittsburgh and Eagle Seams, respectively. The physical parameters and equipment employed for both panels are 1 isled in Table 1. Figure 1 shows the detailed characteristics of the coal seams. Notice in both panels floor cutting was involved either to gain sufficient mining height or to reduce the adverse effects associated with a soft floor.The purpose of the research is to define the dust distribution at any instance in the longwall face area so that proper working positions can be determined and/or effective dust control techniques can be developed.This paper presents the partial results obtained during the first year."

Jan 1, 1988

By Jon C. Volkwein

Advances in mining technology have enabled deeper seams of coal to be mined from the surface. Highwall mining is frequently used to mine areas at the perimeters of a surface mine when removal of the overburden becomes uneconomical or threatens environmentally sensitive surface features. At the same time, advances in materials and technology have enabled highwall mining of coal that create blind headings over 300 meters in length. Deeper surface mining and deeper highwall penetration depths have lead to more frequent encounters with methane gas. While this coal is remotely mined from the surface, underground ignitions of methane have propagated to the surface and injured miners. Methods described in this paper show how this hazard can be correctly monitored and controlled for auger type highwall mining machines. Research indicates that small quantities of gas liberated during mining migrate to the face, creating higher gas concentrations than would otherwise be expected. Using the same principles that cause the gas to migrate to the face, researchers have shown that inert gas introduced at the collar of the hole can inert the entire hole, thus ensuring safe conditions for mining.

By C. Özgen Karacan

Degasification and methane control in underground coal mining is an important area augmenting conventional ventilation in order to prevent possible fires and explosions due to excessive methane emissions. Coal bed reservoir engineering has been applied for many years to coalbed methane production. In recent years, modeling the flow and draining methane, not only from coal bed itself but also from the overlying strata, have been recognized as important areas of expertise for supplementing underground ventilation. This paper demonstrates the applications of coal bed reservoir engineering and modeling techniques for optimizing and controlling methane emissions in longwall and continuous miner sections. Practical applications and some considerations are presented for reservoir modeling, borehole performances, and face emission predictions for various coal bed and borehole configurations. A section on field reservoir studies and well bore log analyses for methane control are also presented as a complementary way of controlling methane and optimizing ventilation.

Jan 1, 2009

By R. E. Perry

In connection with a program of coal research at the Southern Experiment Station the Bureau of Mines, in cooperation with the University of Alabama and the various coal operators, conducts washability studies of coal from beds in Alabama and other Southern States in which commercially important deposits occur. One of the main objectives of a washability study is to obtain technically and commercially important data necessary for determining the best methods for preparing and utilizing the Nation's limited reserves of coking coal. Such information is important to conservation because it facilitates selection of preparation methods that will provide maximum yields of coal with low ash and sulfur contents.

Jan 1, 1958

By R. V. Ramani, R. A. Jankowski, R. Bhaskar

"The spatial distribution of airborne dusts, deposition of dust in the airway, as well as the effect of airflow velocity and particle density on dust behavior in mine airways were studied in a set of experiments performed in a mine airway under controlled conditions. Considerable deposition of dust near the source was indicated. Pronounced effects due to velocity were observed in ambient dust concentration and deposition along the mine airway, both in the respirable and the total size ranges. Cross-sectional concentration measurements indicate an increase in concentration from the roof to the floor. The average cross-sectional concentration is about 75% of the concentration in the center of the airway.IntroductionA number of studies have been performed since the early 1950s on the behavior of dust in mine air (Bradshaw and Godbert, 1954; Dawes and Slack, 1954; Bradshaw et al., 1954; Hall, 1955-56; Reinhardt, 1971; Ford, 1971; Courtney et al., 1982). While the experimental data available from these studies are indeed useful in understanding dust cloud behavior in a specific situation, no generalized conclusions can be drawn because of the lack of data on parameters such as flow velocity, size distribution of the source dust, and particle density. These change from mine to mine or even within the same mine. The present study is aimed at providing a better understanding of the temporal and spatial behavior of dust particles in underground' mine airways (National Academy of Sciences, 1980). The characteristics studied encompassed airborne concentrations and floor depositions over the entire size range as well as the respirable size range. The experimental results in this paper are intended to complement a mathematical model developed to predict ambient concentration and deposition of airborne dust in mine airways (Bhaskar and Ramani, 1986)."

Aug 31, 1989

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 Hiram C. Draper

The Mining Division of the Bureau of Mines, in cooperation with the Obstacle and Demolition Branch, Engineer Research and Development Laboratories, Department of the Army, undertook some extensive tests to determine the effectiveness and limitations of using standard demolition-type shaped charges in underground Mining. The tests proved the shaped charge has no practical application in the functions of mining covered by this report. At an approximate cost of 0 per foot hole plus spall produced by the most efficient single shots with the M3 shaped charge, the cost is over 20 times that of producing a better hole with a rock drill. The concussion would prohibit its use in many mines, and the excess carbon monoxide gas liberated by the pontolite explosive would be an additional hazard when used underground.

Jan 1, 1948

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

By John Taber, Robert D. O'Brien

"INTRODUCTION The Bozeman corundum deposit was first examined in May 1944 by an engineer of the Bureau of Mines. In August 1944, the property was re-examined because of a sharply increased war demand for corundum. A small program of trench exploring was undertaken after the second examination. The work was started in October 1944 and was completed in December 1944. This report presents the essential data obtained by the exploratory work.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end 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 exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploration work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests.The field work on the Bear Trap project was supervised by E. W. Newman, district engineer Montana District office. The microscopic examinations and. the grid grain-count analyses of the samples and the beneficiation tests were made at the Bureau's laboratory at Salt Lake City, Utah, under the direction of S. R. Zimmerley, chief, Salt Lake City Division, Metallurgical Branch."

May 1, 1947

By M. Howard Berliner

In August 1943 the Bureau of Mines completed seven churn-drill holes in an area of old mine workings near Linden, Wis., formerly known as the Argall mine. The work was undertaken as part of a general investigation by the Bureau of the zinc and lead producing area of southwestern Wisconsin at a time when special effort was being made to increase the production of metals necessary for war. The area was selected for investigation on the basis of its favorable geologic structure, past history, and apparent mineralization.

Jan 1, 1948