Search Documents

By Foster Fraas

One of the lithium minerals most widespread in the earth's surface is spodumene (Li2O-A1203-4Si02) a lithium aluminium silicate. For some time, deposits of this mineral were known to exist in the Black Rills of South Dakota, but it was only quite recently that Hess4/ pointed out the great magnitude of the low-grade e deposits it s in North Carolina. The theoretical lithia (Li20) content of spodumene is 8.04 percent. The only other minerals with such high lithia content are the phosphates, but these occur only in pockets and are not in extensive deposits5/. Actually, however, the lithia content in spodumene is never found to be this high, being nearly always below 7 percent for the pure mineral, and part of the lithia is apparently replaced by other alkalies.

Jan 1, 1937

The Bureau has published much data on sulfur (4, 15, 23)3, most of it dealing with national or international aspects of the sulfur industry. Little information, however, is available on sulfur marketing in specific States or areas, Therefore, the Bureau has conducted a survey of the resources, production, consumption, and economic future of the sulfur and sulfuric acid industry in States of the Central and Southern Rocky Mountain area - Wyoming, Colorado, Utah, Arizona, and New Mexico - and in the Northern Plains States - North Dakota, South Dakota, and Nebraska, even though these States do not represent an economic or marketing unit. The purpose of this survey is to review the demand for sulfur and primary sulfur compounds that draws upon the natural resources of the region, to discover opportunities for better use of these resources, and also to analyze and evaluate the patterns of consumption, sources of supply, and other factors that affect the demand for these mineral products. While this survey stresses the economic and marketing phases of the industry, a complementary report (32) emphasizes the resources of sulfur in Wyoming, Colorado, Utah, New Mexico, and Arizona.

Jan 1, 1962

By Forrest T. Moyer

The overall disabling work injury experience, excluding office- workers, at nometal mines and mills during the period 1961-63, as reported to the Bureau of Mines by operators, was 77 fatal and 7,201 nonfatal injuries during an aggregate worktime of 335,029,685 man- hours. These injuries, fatal and nonfatal combined, occurred at a frequency rate of 21.72 per million man-hours, comprising 0.23 for the fatal and 21.49 for the nonfatal injuries. The combined severity rate of the disabilities was 2,312 days lost or charged per million man-hours, consisting of 1,379 for the fatal and 933 of the nonfatal injuries, The average severity of all disabilities during 1961-63, was 106 days per injury, The number of days lost or charged, excluding officeworkers, at nonmetal mines and mills during 1961-63, was 462,000 days charged to fatal injuries and 312,461 days lost from nonfatal injuries. The outstanding causes for fatal injuries were explosions (18 fatalities occurred in a major mine-explosion disaster in a potash mine in Utah in 1963) and falls of rock or ore from back or side, while most nonfatal injuries were caused by handling materials, slips or falls of persons, haulage, and machinery. The parts of the body most frequently injured during the period 1961-63 were the trunk, hand and finger, and foot and toe, An average of 52,810 men were at work daily, There were 20 nonfatal disabling injuries reported for office- workers at nonmetal mines and mills during the period 1961-63 during an aggregate worktime of 23,088,496 man-hours, These injuries occur- red at a frequency rate of 0.87 per million man-hours, There were no fatal injuries reported.

Jan 1, 1967

By Arnis Mangolds

A study of the technical and economic feasibility of using a unique undercut and fill system developed by USBM engineers to mine steeply pitching coal is discussed. A brief resource assessment has indicated that significant reserves exist in most coal regions to justify the development of a safe and economical method of extracting steeply pitching coal. The undercut and fill system combines hydraulic coal cutting with unassisted gravity fluming of the coal slurry. Mining occurs across strike and the extended entry is backfilled to provide uniform strata control and an impermeable water and air barrier. Subsequent mining occurs beneath the previously filled stope such that the roof consists of a solid, controlled back. In addition to providing positive roof and hanging-wall support, the backfill system eliminates subsidence potential, post-mining drainage, and the danger of spontaneous combustion from naturally drafting air currents. A unique through-flowing ventilation system permits passage of return air through the production face via ducting located at the backfill-coal junction. This provides a constant supply of fresh air at the face, eliminates the need for brattice cloths, and provides an additional escapeway for the miners. The preliminary estimates indicate a production rate in the neighborhood of 31.9 tons/ manshift. Capital costs are approximately $3.17/raw ton over a 20-year life with an initial investment per annual ton of $48.29. Total cash-costs for labor, supplies, power and benefits range in the vicinity of $19.59 for a 704,460 ton/year mine, or a total cost of $22.76/ton. These costs do not include federal and local taxes or post-of-money; however, the cost of coal is well within the area selling price.

Jan 1, 1981

By Nikolaos Polysos, Holger Witthaus

INTRODUCTION The classification system for German coal mining is the result of approximately 100 years of experience in roadway development and longwall mining. It is also based on different research projects covered by national and European research programs. Over the past 30 years, more then 600,000 m of road-ways have been driven and employed for mining activities. To properly describe the German rock mass classification system, therefore, it is useful to take a look at the main geomechanical preferences and common support systems. The decision about the most effective development technique and support system is based on a synthesis of rock mass classification and geomechanical analysis. The properties of surrounding rock, the in situ stress, and the influence of mining activities in several seams at each German mine must be considered for the evaluation of the expected deformation of the roadway. The mine layout, the requirements of ventilation and fire prevention, as well as the need to maintain emergency escape routes for the miners, require that the gate roads remain usable after the passage of the longwall face in most cases. Moreover, the gate roads must be maintained despite the high stresses that are applied during longwall retreat mining. Therefore, gate road design must address a broad spectrum of potential deformation environments. In the past, when gate roads were supported solely with yielding steel arches, lithologic descriptions of the surrounding strata conditions were adequate for the dimensioning of support and the prediction of the roadway deformation. The current conditions of multiple-seam mining at depths of up to 1,700 m require combined support systems, including pattern bolting and backfilled steel arches. Rock bolt support is used for development, after which (typically 50–100 m outby the face) the steel arches are installed and backfilled with building material (concrete) in order to achieve an optimized development rate. The rock mass classification system described below was developed especially for the conditions of German hard-coal mining. It includes the stress distribution caused by multiseam workings (including crossing goaf edges of former longwalls), as well as in situ stresses due to greatdepth and the presence of tectonic faults. It is based on the evaluation of four parameters: • Geotechnical analysis of drill cores • Geotechnical observation of the development face • Geotechnical classification of tectonic structures (faults) • Standard classification derived from geotechnical assessment and evaluation of stress conditions (using numerical modeling for stress calculation) ROCK STRENGTH One of the most important input parameters for describing strata conditions is the strength of the rock. The German classification system is based on a description of lithotypes. This method has been used successfully since the 1950s and is based mainly on the uniaxial compressive strength (UCS) of the material. An evaluation of the rock strength observed in a survey of approximately 82,500 samples of rock core yielded the results shown in Figure 1. The three most common coal measure rock types are mudstone, siltstone, and sandstone. Each shows a specific mean UCS level and a different spread between the minimum and maximum values. Sandstones, in particular, have a wide spectrum of compressive strength, ranging from approximately 40 MPa to greater than 130 MPa, with an average of 85 MPa. The causes of this wide range include different sedimento-logical preconditions, facies, and digenetic processes. [ ]

Jan 5, 2007

By A. R. Taylor

In recent years, thermodynamic data have been used to a greater degree than ever by the chemical and metallurgical engineer as a means of predicting and controlling chemical reactions. To satisfy the spiraling demand for basic physical data needed for the calculations, the Bureau of Mines is studying the heat capacities of a variety of chemical compounds at high and low temperatures. This paper is one of a series presenting such data. The heat capacities of two alkaline earth compounds, strontium bromide and strontium nitrate, were measured in a temperature range of 60° to 300° K. in an adiabatic calorimeter and at temperatures of 300° to about 1,200° K. in a Bunsen ice calorimeter. The construction and operation of the calorimeters are discussed in other reports.3 4 The heat-capacity data presented in this report were extrapolated to 0° K., and smooth values of heat capacity, entropy, enthalpy function, and free-energy function were calculated and tabulated at even 10-degree intervals. The enthalpy data were fitted with algebraic equations by applying the method of least squares; calculations a£ heat-capacity values, entropy, enthalpy function, and free-energy function were made at even 50-degree intervals. The heat and entropy of fusion of strontium bromide were calculated from the enthalpy measurements.

Jan 1, 1962

By Robert M. Baker

This document details the method whereby Allen Corporation of America gathered and analyzed data and developed an annotated bibliography of metal and nonmetal mine fire reports (1950-1979). The primary objective of this program was to develop the annotated bibliography which included MSHA accident reports and periodicals. Two additional objectives were to gather data on non-reportable fires and to conduct statistical analyses on the data to delineate trends. Data was acquired from three major areas: periodicals, MSHA fire reports, and mine safety directors. Data was separated into reportable fires (at least ½ - hour duration or injury), non-reportable fires, and opinion data. The data was then analyzed by time trends, state, ore, ignition source, burning substance, location, equipment, detection, duration, injuries, fatalities, and successful extinguishing agent. The authors make a number of recommendations: (1) improved stationary electrical equipment design and fire protection, (2) improved design of mobile equipment to separate combustibles from ignition sources, (3) improved maintenance, (4) improved housekeeping, and (5) improved training. The document is divided into two volumes and an appendix. Volume I contains data acquisition procedures, data analysis procedures, and conclusions and recommendations. Volume II contains a chronological list of mine fires and fifteen indexes to assist the reader in locating fire incident report of interest. The Appendix contains the annotated bibliography of over 300 metal and nonmetal mine fire reports and journal articles and a list of non-reportable fires.

Jan 1, 1980

By John A. Johnson

For the purpose of comparing the amounts of dust produced by various mining operations, samples of atmospheric dust were collected during a complete cycle of drilling, blasting and mucking at or near the face of the Bureau's Mount Weather testing adit while the efficiency of several types of stemming in metal-mine blasting was being investigated. ACKNOWLEDGMENTS All gas samples were analyzed in the laboratory of the Bureau of Mines Gas Section at Pittsburgh, Pa.

Jan 1, 1939

By Kenneth H. Johnston

The Weber pool in Washington County, Okla. (fig. 1), covers an area extending from 2 miles east and slightly north of Bartlesville, Okla., to a point approximately 2-1P tiles northeast of Dewey, Okla. The pool is a part of the area designated by the Standing Committee on Oil Field Nomenclature, Kansas-Oklahoma Division, Mid-Continent Oil & Gas Association, as the Bartlesville-Dewey field. In the following discussion of the geology, development, and exploitation of the Weber pool, the writers, by means of structure maps, cross sections through various parts of the reservoir, and tabulated development data and production statistics, have recorded salient information on a field that was developed before .1910 in an Area that has been repressured since 1926. The total oil production to January 1, 19.0., from the 2,639 developed acres considered in this report, was approximately 14 million barrels, or a recovery of about 5,3;2 barrels per acre, or 227 barrels per acre-foot. The production of the estimated 18 million barrels of recoverable oil remaining in the Bartlesville sand reservoir will require the initiation of additional secondary-recovery practices on some of the leases and the application of a more systematic repressuring program on others.

Jan 1, 1950

By E. J. Gleim

A list of permissible mine equipment, tested and approved by the Bureau of Mines previous to January 1, 1942, was published in Bureau of Mines Information Circular 7207.3/ The list of that date was complete as to equipment then available and in current use. Information Circular 7240,4/ published as a supplement thereto, listed equipment approved curing the calendar year 1943. The present list is another supplement covering approvals issued during the calendar year 1943. The items are numbered to indicate the consecutive order in which each type of machine or device was approved in its particular classification. Thus, Information Circular 7207 gave 19 drills and drilling machines on the Bureau's active list. No additional approvals were given in 1942, but the three issued in 1943 bring the total to 22. Item 102, under Loading Machines and Conveyors, also appeared in Information Circular 7207, and items 120 and 124 appeared in Information Circular 7240. These numbers are repeated here to show that approvals were granted during 1943 for additional voltages on machines previously listed for one voltage only. Equipment listed in these circulars is approved by the Bureau of Mines only when found upon inspection and test to comply with minimum standards of safety as outlined in schedules prepared on the basis of many years of experience in dealing with safety problems of the coal-mining industry. The use of such equipment in mines known to be gassy, as well as in those that may become so, is earnestly recommended in the interests of safety. This circular is published so that the industry may be kept

Jan 1, 1944

By G. L. Oldright, J. D. Sullivan, W. E. Keck

"An apparatus and procedure developed in the laboratory of the South-west Experiment Station of the Bureau of Mines are capable not only of determining the rate and volume of penetration of solutions into porous materials but also of determining the total volume of voids within particles of porous material, and the density. The method is applicable to ores, bricks, concretes, tiles, filter bottoms, or other porous materials of this nature. As will be made clear in the descriptive matter to follow, the method measures (a) the volume of voids within the porous materials and is not concerned with the interstitial space between the particles.Porous materials usually contain some large voids and also pores that are capillary in nature. To measure the total volume of voids in a sample it is necessary to replace the gas or gases within the voids with some liquid of known density. The large cavities can be filled quite readily, but under ordinary conditions a long time may be required to fill capillary pores. As many porous materials are of a decomposable nature it is necessary to evacuate the porous materials and then submerge them in a liquid of known density to bring about saturation in a short time. Then by the use of a hydrostatic balance the volume of porous material (solid itself) can be determined. To determine the volume of porous material plus voids it is necessary to coat the sample with some material, such s paraffin, which will prevent solution from entering the voids; then, by means of a hydrostatic balance, the volume of porous material plus voids is determined and by subtracting that of the porous material from this the volume of voids is ascertained. The rate of penetration of solutions can be determined either (a) by measuring the change in weight as the sample becomes saturated when immersed ni a liquid of know density, or (b) by measuring the volume of liquid penetrating with a dilatometer. In either instance, due to the fact that some penetration takes place as soon as the sample comes in contact with solution and before a reading can be taken, the sample must be paraffined to determine the total volume of penetration. Since many porous materials partly decompose and disintegrate in liquids the rate and volume of penetration can better be measured by dilatometer than by the change in weight, as saturation takes place when immersed in a liquid. The details of procedure for determining (a) total volume of voids, and (b) rate and volume of penetration are given in this paper."

Oct 1, 1930

By Pablo Velasco

The Belize economy recorded modest growth during 1980; the growth of the gross domestic product (GDP) in real terms was between 1% and 2%. At current prices, the 1980 GDP reached $108 million2. This output was largely attributed to the performance of a few industries, mostly nonminerals. Such performance improved significantly the balance of payments situation by reducing the deficit from $19 million in 1979 to $4 million in 1980. The rate of inflation was an estimated 18% in 1980 and would have been greater if not for a conservative monetary policy and price control on a number of essential items. Expert earnings increased $43 million, or 50%, from the 1979 level. After increasing more than 25% in 1979, imports increased only 6% in 1980 to a level of $141 million owing to the decline in investment and stabilization of petroleum prices. The balance of trade deficit was $9.8 million in 1980, a marked improvement from the 1979 level of $45.1 million. The mineral output for Belize accounted for only a fraction of 1% of the GDP. Such activity was limited to the production of limestone, marl, and sand and gravel, all of which were primarily used in construction of the Northern Highway between Orangewalk and Belize City. Mineral resources are deficient or nonexistent in Belize for the majority of metals and nonmetals, although the Government and others continue to believe that petroleum must exist in Belize. The proximity to Mexican oilfields and the growing finds in the Peters area of Guatemala support this expectation. The Government continues encouraging exploration onshore and offshore and offers terms that

Jan 1, 1982

By Maurice J. Peterson

The applications of optical spectrochemical methods of analysis for determining trace impurities in metals are described, and the need for developing analytical procedures capable of accurately determining fractional parts per million of impurity elements in metals is stressed. Factors which determine sensitivity of detection and means to extend sensitivity levels in spectrochemical methods are discussed. Examples from the current literature illustrate the diversity of spectrochemical techniques that have been applied to the analyses of varied sample types, Many of the methods use preconcentration procedures to increase sensitivity limits. A bibliography containing abstracts of recent methods in included. Optical spectrochemical analysis is based upon the measurement of radiant energy emitted by atoms of the elements to be determined when a sample is subjected to a suitable source of excitation. The behavior of the valence electrons during excitation, usually by an arc, spark, or flame, produces radiant energy of specific wavelengths. This is recorded as spectral line images on a photographic film or plate by the spectrograph; for direct-reading instruments, the spectral lines are detected with photomultiplier tubes. The spectral lines result from the excitation of atoms in the sample. Each variety of atom produces its own characteristic set of lines, thus serving to identify the elements in the sample. Increased concentrations of elements in the excited sample results in increased blackening of the spectral line images.

Jan 1, 1961

By Francis E. Federspiel

In 1984 and 1985, at the request of the U.S. Forest Service, the U.S. Bureau of Mines examined the 87,720-acre South Boise Yuba study area (formerly known as RARE II Wilderness Recommended area I-4553) to evaluate mineral resources. The study area and additions are in Blaine, Camas, and Elmore Counties, 10, about 60 mi east of Boise. Granitic rocks of the Cretaceous age Idaho Batholith occupy the western two-thirds of the study area. A Tertiary age granitic complex has intruded, and broken into small blocks, Paleozoic age sedimentary rocks in the eastern third of the study area. Tertiary Challis Volcanics overlie both of these rock types. Principal mineralized structures are gold-and silver-bearing quartz veins and shear zones trending northwest to easterly in the Cretaceous granitic rocks. Copper, lead, and zinc are accessory metals in many mineralized structures.

Jan 1, 1987

By J. R. Ross

Recovery of uranium from slightly alkaline mine water, available in the Ambrosia Lake district of New Mexico, was studied using countercurrent ion exchange columns developed by the Bureau of Mines. Approximately 5 million gallons of mine water containing 9 to 12 ppm U308 was treated by ion exchange using a 14-inch-diameter absorption column composed of five or six compartments each 4 feet deep. Uranium recoveries averaged in excess of 98 percent at solution flows ranging from 15 to 25 gallons per square foot per minute and resin loadings up to 3.6 pounds of U.08 per cubic foot. In subsequent tests, loaded resin was continuously eluted in a countercurrent elution column with a diameter of 4 inches and containing a bed of resin 9 feet deep. The resin was eluted to a residual loading of less than 0.06 pound of U305 per cubic foot, at a resin-retention time of 224 minutes, using only 1.9 volumes of 1.1 M NaCl-0.05 M NaHCO3 solution per volume of resin. Compared with existing ion exchange practices for recovering uranium from mine waters in the Ambrosia Lake district of New Mexico, use of these improved ion exchange contactors would reduce ion exchange resin requirements at least 70 percent and allow further substantial reductions in capital and operating costs.

Jan 1, 1971

By G. S. Rice, H. O. Howarth, Greenwald. H. P.

"Electricity as a means of transmitting power was introduced in coal mines of the United States about 1891 for both haulage and coal cutting, only a few years after electrical haulage was first installed on street cars. At first, the hazards of electrical ignition ere not appreciated and the general use of open lights and black blasting powder made the possibility of electrical ignition of fire damp seem small by comparison.5 The possibility of igniting coal dust directly by electric sparks or arcs had not been considered.In the nine years prior to 1900, the progress of introducing electricity underground was slow, except that it was used for lighting shaft bottoms. Electricity had to contend with the more general use of compressed air for coal-cutting machines and, in mainline haulage, with the use of mule-teams and endless and tail-rope systems. During this period, great improvements were made in electrical apparatus, in surface installations as well as in mines. By 1900, therefore, the technique of applying electricity in mines had so far developed that it rapidly drove out the use of compressed air in coal mines because of the comparative ease of its installation and the marked economic advantages of its use over that of compressed air in practically all kinds of mining machines except percussion. rock drills.At this time, however, little thought was given to the hazard of indiscriminate use of electricity causing explosions and fires, and the possibility of electricity causing direct ignition of coal dust had not been considered. On December6, 1907, however, the Monongah, West Va. mine explosion occurred. This was the greatest mine disaster this country has over had, 361 men being killed. Although: there was much diversity of opinion, as to the origin of the explosion, many well-informed engineers concluded that the cause was ignition of coal dust do to wreckage of a runaway trip in a rope haulage entrance slope. This slope also served as a ventilating and it extended from the level of the coal bed to the surface. The runaway trip tore down electric cables and stirred up a cloud of dust when it was wrecked at the bottom of the slope. The dust was probably ignited by the electric arcing that occurred when the wires were knocked down. (Another but less probable source of ignition was the open flames of miners lamps.) From the foot of the slops the explosion appeared to have travelled into the mine, spreading as it went. If this ignition of coal dust was the origin of the explosion, it occurred on pure intake air entering directly from the surface."

Oct 1, 1930

By C. H. Titus

This study consists of four descriptive Sections covering respectively: a state-of-the-art literature survey on ungrounded and grounded power systems, a report on literature pertaining to human threshold limits of electric shock, an analysis of the performance requirements of isolated systems and a section on design and performance specifications for an isolated system the final section includes copies, and translations where applicable, of the most important articles on foreign mining practice as well as some technical publications which could be difficult to obtain elsewhere. Section 2 - Literature Survey In analyzing the available literature on ungrounded systems it became apparent that too strict an interpretation of Section 1.1 of the Contract would limit the survey in both period of time analyzed and in available literature which discussed several types of power systems. Therefore, the survey was expanded to cover approximately the past twenty-year period and to cover literature which addressed itself to both ungrounded and grounded power system operation. Section 2 gives a brief summary of this literature survey and lists the important papers and books which were examined.

Jan 1, 1972

By K. E. Robinson

This study is the extension of an investigation of reclamation of floodplain areas in the Coeur d'Alene Mining District, Idaho, that are unuseable in their natural condition, by construction of landfills with mill tailings. The study develops a valley-wide tailings disposal plan to utilize 20 potential landfill sites on floodplain areas and presents measures for reclaiming the sites for subsequent productive use. Field and laboratory testing on a test section and two abandoned impoundments support the use of hydraulically deposited tailings for landfill construction. Hydrological testing has shown that controlled discharge from tailings impoundments results in contaminant levels in the discharge below regulated standards. Additional testing indicated that compacted soil liners and pond management provide adequate contaminant abatement where acid-generating tailings are encountered. Mechanical compaction, including surcharge loading, upgrades foundation support capacity so that construction on the surface of tailings deposits is feasible. On completion of the testing program, the test sections were abandoned and rehabilitated. Details concerning potential landfill sites have been refined. At recent production rates, the 20 sites would result in 680 acres of reclaimed land, while providing a minimum of 40 years of tailings storage capacity. A general design has been developed for the retention dikes. Aspects of embankment stability, including liquefaction are discussed, and are shown to provide an adequate factor of safety under the anticipated range of operating conditions.

Jan 1, 1983

By R. L. Levens

Researchers at the U. S. Bureau of Mines conducted investigations to evaluate the potential for ground water contamination by mine waste used as backfill. Samples of cemented waste backfill and water discharging from drillholes and seeps were collected to use in chemical analyses and laboratory tests to determine the physical and chemical factors that control release of heavy metals to ground water. Greater water retention by cemented backfill (as compared to uncemented sandfill) reduces the surface area exposed to oxidation, which in turn reduces the amount of acid produced. The acid is neutralized by the cement and minerals contained in the backfill. The grain-size distribution of tailings used for backfill affects the structural integrity of cemented backfill under attack by acidic water; breakdown of the backfill structure releases neutralizing materials faster. Backfilled stopes in rock with low hydraulic conductivities will constitute preferential flow paths after mine flooding; however, the rate of flow through backfill will be much slower than when the stope is partially saturated during mine operation. Considering all factors, acid generation and release of metal ions from cemented backfill should be less than in uncemented sandfill.

Jan 1, 2010

By Burton Scott

A device for detecting carbon monoxide at ppm levels is described which is based on the measurement of infrared absorption at 4.65 microns. The unique feature of the nondispersive infrared instrument is contained in the optical design which includes a confocal cavity, increasing the effective optical path length by a large factor, thus greatly reducing the required package size. The cavity has the effect of reducing the total amount of radiation passing to the detector, but at the same time increasing the percent attenuation observed when adding CO, by a factor called gain. The radiation is chopped by a filter wheel which contains narrow band filters at 4.0 and 4.65 microns. The resultant signal produced by the pyroelectric detector is demodulated by the electronics to product an automatic gain control signal, proportional to the total radiation, and a difference signal, proportional to the CO present. Tests of a breadboard model are described which show cavity gains of 10 with noise levels equivalent to 2 to 10 ppm CO.

Jan 1, 1975