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By George R. Schottler

The Bureau of Mines investigated the distribution of uranium and various methods of ore sampling in a uranium deposit typical of those in the Morrison Formation sandstone of the Ambrosia Lake area, Grants mining district, north-western New Mexico. Chemical and radiometric assays of diamond-drill core samples are compared in detail by statistical techniques, and the assay data are correlated with the stratigraphy of the deposit. Conclusions applicable to ore-reserve estimation in geologically similar uranium deposits are drawn.

Jan 1, 1971

By Doris M. Hyde

Limited geographically by size and geo-logically by origin, smaller countries and territories of the Caribbean are nonetheless engaging in efforts to encourage the initiation of mineral and mineral-related industries. Petroleum dominates the minerals sector, which otherwise consists principally of minor quantities of construction-oriented materials, usually for local consumption. The increased cost of petroleum has adversely affected most of the world, but these islands with their economies precariously balanced on the uncertainties of agriculture and tourism are especially vulnerable to petroleum's direct and indirect costs. In 1975, the Government of Antigua acquired the financially troubled West Indies Oil Company refinery at St. Johns. The refinery ceased operations in 1976. In 1979, negotiations were underway to sell Ashland Oil Co. an interest in the small, 20,000-barrel-per-day refinery for $6.6 million. In 1977, Antigua granted petroleum exploration rights to the Antigua Mineral Exploration Company, which planned to drill in an undefined offshore area, possibly between Antigua and Barbuda. The company expected to spend about $200,000 per year through 1982. There have been no reports on its activity.

Jan 1, 1981

By H. G. Iverson

An investigation was conducted on the conditions affecting the precipitation of aluminum by autoclaving synthetic solutions containing Na2SO4, Al2(SO4)3, H2SO4, and H2O. Virtually all of the alumina could be precipitated as natroalunite (NaAl3(SO4)2 (OH)6). This product could be readily filtered and dried. Results are reported in terms of alumina precipitated in this compound and not in terms of alumina itself. Solutions of ~ 0.30, ~ 0.60, and ~ 0.80 mole/liter A1203 and various concentrations of H2SO4 and Na2S04 were investigated. The optimum time and temperature for autoclaving were 20 to 30 minutes at 200° C. The highest yields of natroalunite were obtained from solutions containing little H2SO4 and ~ 2 moles Na2SO4 per mole A1202. Acid in quantities of 0.3 to 0.5 mole/mole of alumina in solution depressed the yield to 90 percent or less. In differential thermal analysis, at 1,000° C the natroalunite precipitate decomposed without melting to yield SO, and SO2 gases, a solid composed of Na2SO4, and gamma and alpha Al203. Continued heating to 1,200° C produced No SO, and alpha A1303. Water-leaching of this product removed the Na2S04 and left a final residue of alpha A1203.

Jan 1, 1968

By J. E. Zeilinger

This Bureau of Mines report describes the preparation characteristics of the significant coalbeds of Clarion County, Pa. Of the 15 samples collected, 1 was of metallurgical quality as received, 4 could be sufficiently upgraded to provide acceptable products, and the remaining 10 samples could not be upgraded to metallurgical quality because their sulfur contents could not be lowered to meet the standard. For steam or power generation, 1 sample was of low sulfur content as received, 1 sample could be upgraded to low sulfur content, and 10 samples could be upgraded to medium sulfur content. The original sulfur content of the remaining three samples can be appreciably reduced by removal of the sink 1.58 specific gravity material; however, these coals would be classified as medium sulfur coals both before and after removal of the sink material.

Jan 1, 1968

By Howard E. Parkinson

The mine pager phone to public telephone interconnect system permits mine paging telephones to be interconnected with the public phone system, thereby providing emergency and off-hours communications. The system, a push-to-talk, push-to-listen system, is compatible with any mine paging system utilizing dc voltage on the line to enable paging. A tone generator of the proper frequency enables an outside caller to page over mine pager system loudspeakers. A caller inside the mine can make an outgoing call to a preselected, preprogramed number with the use of a proper frequency tone generator. The system includes an automatic hangup timer that restricts the time off-line due to a wrong number or incorrect hangup to 20 seconds and 6 minutes, respectively.

Jan 1, 1974

By Jon K. Ahlness

The Bureau of Mines, in cooperation with the Institute of Mineral Research of Michigan Technological University, and the Upper Great Lakes Regional Commission, conducted an investigation of electronic sorting of native copper ore from Upper Michigan. This report is based on research by the Institute of Mineral Research under contract to the Bureau. The test program evaluated the use of belt and rotary sorters on various size and grade fractions of ore. Both plant-scale sorting and lab sorting tests were run. The plant sorting objectives were to determine the sortability of different ores and the efficiency of the electronic ore sorters. High-and low-grade ores from both conglomerate and amygdaloid types were separated into four size fractions. The two larger sizes were sorted on belt sorters and the two smaller ones on rotary sorters. Copper recoveries ranged from 20.0 pct from a feed grade of 0.40 pct to 80.3 pct from a feed grade of 1.08 pct. Lab sorting tests of conglomerate ore were run to determine the efficiency of a belt sorter equipped with a second sensing coil located above the belt and to determine the sorting characteristics of larger ore size fractions than those used in the plant sorting. Copper recoveries from the combined feed sizes ranged from 47.0 pct from a feed grade of 0.13 pct to 96.8 pct from a feed grade of 4.87 pct. For all the ore types except one, it was found that the copper recovery increased with the feed size.

Jan 1, 1980

By R. R. Brandenthaler

A series of open-flow tests was conducted in the Chickasha gas field, Grady County, Oklahoma, during June, 1927, under the direction of the U. S. Bureau of Mines and at the request of the Oklahoma Corporation Commission. The purpose of these teats was to determine whether or not any differences existed in the open-flow volume of a gas well when taken through well-head nipples of different diameters, and further, to establish if possible a relationship between open-flow volumes taken through well-head nipples of various diameters. The open flow of a well is the volume or quantity of gas, measured under standard conditions, that a well will produce when open to the atmosphere. There are several methods used for determining the open flow of wells; some of the methods are more suitable under certain conditions than others. The Pitot tube method is the simplest, is applicable to almost any condition, and is the one most commonly used. In the tests described in this paper no attempt was made to compare the Pitot tube method with the minute pressure measurement method or the orifice measurement method.5

Jan 1, 1928

By P. W. Jerant

The methane emissions from an advancing coal mine section were continuously monitored for 120 days. During this time, the section advanced 2,000 feet into virgin Pittsburgh coalbed producing 54,565 tons of coal with a total methane emission of 91 million ft3. Analysis of the data gathered showed that daily methane emissions did not correlate with overburden thickness and daily coal production. A good correlation was found between the daily methane emission and the average length of rib exposed to virgin coal.

Jan 1, 1976

By F. E. Spencer

This Bureau of Mines report provides a complete mathematical description of the algorithm employed by a general multiphase chemical equilibrium program developed particularly for the purpose of studying problems in coal combustion, although the generality of the program will allow its application to any equilibrium system in which an appreciable gas phase is present. When applied to coal combustion problems, the program predicts composition and quantity of slag and unconsumed carbon phases as well as calculates accurately the composition of the gas phase including trace species such as free electrons and ions which are important for predicting electrical properties.

Jan 1, 1973

By d&apos, Kathleen J. Amico

THIS SUMMARY is shown in volumes I and III of this series on mineral production in the United States (including Alaska and Hawaii), its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, and on the principal minerals imported into and exported from the United States. For further details on production, see the several commodity and area chapters. A summary table comparing world and U.S. mineral production also is included. [ ]

Jan 1, 1960

By Kelly C. Strebig

Laboratory tests were conducted by the Bureau of Mines to determine the effect of depth of cut and bit type on respirable coal dust generation. Apparatuses were constructed to contain the coal samples, measure the linear cutting forces, and analyze the dust generated. Single-bit tests were conducted in Illinois No. 5 and Pittsburgh seam coals with five bit types at four depths of cut. The results showed that bit type did not significantly influence dust production. On the other hand, deep-cutting bits were more efficient and generated substantially less respirable dust per pound of coal broke than shallow-cutting bits.

Jan 1, 1975

Large quantities of combustible materials are often found in underground metal and nonmetal mines, with support timber predominating. Wood lagging and timber, wires and cables, brattice cloth, hose, paper products, cardboard cartons, and wooden containers are additional combustible materials commonly found in underground storage areas. Shorted or overloaded electrical cables, worn sockets and plugs, spontaneous combustion, careless smoking, and welding and cutting are common fire ignition sources. Inexpensive, reliable fire detection and suppression systems are available to provide early warning and to extinguish fires that originate in underground storage areas.

Jan 1, 2011

By Sabri Ergun

Previous studies of magnetic separation of pyrite from coals have been reviewed critically. Magnetic susceptibilities of United States coals of differing rank have been measured. The effects of crushing, magnetic mixing, drying, weathering, and heat treatment on the enhancement of the magnetism of pyrite have been analyzed. The importance of size distribution of pyrite in the coal and the necessity of crushing to liberate the pyrite has been discussed. It has been found that the inherent susceptibilities of the carbonaceous, mineral-free portions of coals (? -0.5 X 10-6 in cgs units) and of relatively pure pyrite isolated from coals (? -0.3 X 10-6) do not permit efficient separation of pyrite from coal; the average susceptibility of the magnetic fraction of coal must be raised to 3 X 10-6. Friction forces encountered in crushing sedimentary pyrite embedded in coal do not increase its susceptibility. Subsequent weathering or heat treatment below 400° C leads to the formation of iron sulfate and hence increases the effective paramagnetism of pyrite. Ferromagnetic compounds of iron are not formed in significant quantities at temperatures below 400° C. The degree of liberation and apparent susceptibility of pyrite are the most important parameters in its separation. It is concluded that effective beneficiation of coals can be achieved by magnetic separation. A sufficient increase in the susceptibility can be achieved by converting less than 0.1 percent of pyrite into ferromagnetic compounds of iron. Such conversions occur only at temperatures >500° C. An investigation of the dielectric properties of coals and pyrite in the frequency range 0.1 to 60 Mhz indicates that the imaginary dielectric constant of the pyrite is about 100 times larger than that of coal. Exploratory experiments indicate that pyrite can be selectively heated to temperatures above 500° C without appreciable rise in the temperature of coal. It appears that dielectric heating of coals in the Ghz frequency range is the most feasible method of enhancing the paramagnetism of pyrite.

Jan 1, 1968

The National Personal Protective Technology Laboratory (NPPTL) of the National Institute for Occupational Safety and Health (NIOSH) has undertaken a collaborative study with the Mine Safety and Health Administration (MSHA) to determine how well self-contained self-rescuers (SCSRs), deployed in accordance with Federal regulations (30 CFR 75.1714), withstand the underground coal mining environment with regard to both physical damage and aging. Apparatus tested included the CSE SR-100, the Draeger OXY-K Plus, the MSA Life-Saver 60, and the Ocenco EBA 6.5 and M-20. This report presents findings regarding laboratory-tested SCSRs in the tenth phase of testing, from July 2004 to March 2006. The SCSRs were tested on a breathing and metabolic simulator and on a human subject walking on a treadmill. The tests performed in this study are not the tests used for certification (Title 42 of the Code of Federal Regulations, Part 84). The tests performed in this study continue until the apparatus are empty to enable comparison of new versus deployed apparatus. The method for obtaining deployed SCSRs for this evaluation was not a random selection from the deployed population of SCSRs. We sought older apparatus with visible environmental impact rather than newer apparatus, and we attempted to sample a wide range of deployment modes. Although the results of these tests are useful for observing performance of the tested SCSRs, they are not representative of all deployed SCSRs. This report is the last of 10 report phases begun in 1982. Previous reports describe phases 1 through 9 [Kyriazi et al. 1986; Kyriazi and Shubilla 1992, 1994, 1996, 2000, 2002, 2004, 2006] A new evaluation protocol, with revised sampling strategies, test methods, and reporting procedures, is currently being designed to enhance the applicability of the results. The results of these studies suggest that the large majority of SCSRs that pass their inspection criteria can be relied upon to provide a safe level of life support for mine escape purposes. However, the storage and handling in the mining environment seems to have caused performance degradation in some of the apparatus. In this phase, phase 10, we found some CSE SR-100s (93 tested) that exhibited high CO2 levels, stuck-together breathing hoses, starter-O2 failure, breathing hose punctures and tears, high breathing pressures, and loose particulates in the breathing hose. The loose particulates caused coughing in human-subject tests. One MSA Life-Saver 60 (20 tested) in this phase had a stuck-open relief valve. One Ocenco EBA 6.5 (50 tested) had an unattached O2 supply hose. An unexplained phenomenon occurred with two Ocenco M-20s (20 tested): low O2 flow rates preventing their successful use. Almost all of the failures noted involved units that failed their inspection criteria.

Jan 6, 2008

By R. V. Ramani, V. T. Burgos, J. A. McClay

Introduction The Cost program was developed to provide the planning engineer with a tool to evaluate the cost implications of the technical mine design decisions. Direct costing methods are employed, where feasible, to provide greater detail and accuracy in the primary cost centers. Options have been provided in the cost computation, economic analysis, and output data subsystems to increase the flexibility of the system. Computer Program The program is written in Fortran IV for use in the IBM System 360/370 computers. i. Main - The main routine reads and stores input data from three sources, user input, Cost Data Library, and data transfer from the Master Design Simulator. Data is trans¬ferred to the appropriate subroutines, as they are called, by means of labeled common blocks. ii. Subroutine CSTCOM - is a data modification routine which computes the peripheral charges related to labor and supervisory costs. iii. Subroutine MANPWR - interrogates section data to determine the total labor and supervisory costs for each cost center. iv. Subroutine CAPCST - computes the total capital investment for each cost center, including the economic life and salvage value of each element. Capital costs are determined by user selection of quantities and models of equipment. Equipment costs are stored in the Cost Data Library for retriev-

Jan 1, 1975

By C. L. Chaney

Investigations were conducted to develop spectrochemical methods capable of determining 0.01 to 100 micrograms of metals in 50 milliliters of solution. The use of gallium hydroxide (Ga(OH)3) as a carrier-precipitant to concentrate metallic ions is described. A porous-cup graphite electrode is used to collect the precipitate. A specially designed plunger permits the electrode assembly to serve as the sample-containing electrode in the subsequent spec-trographic analysis. Analytical curves are presented for antimony, arsenic, beryllium, and zinc. Sensitivities of detection are given for 13 elements. The techniques were applied to identify impurities separated from tungsten, to determine trace impurities in solutions containing high concentrations of magnesium, cobalt, or nickel, and to identify trace impurities in hydrofluoric acid. Laboratory glassware was a serious source of contamination when low levels of zinc were determined.

Jan 1, 1963

By Carla A. Kertis, Alan A. Campoli, Claude A. Goode

This Bureau of Mines study was conducted to obtain a better understanding of the coal mine bump problem and its effect on underground coal mining in the Eastern United States. To accomplish this, information was collected on the geologic conditions, mining techniques, and engineering parameters at five bump-prone mines. Two geologic conditions have been found to cause the occurrence of bumps in the Eastern United States: (1) relatively thick overburden and (2) extremely rigid strata occurring immediately above and below the mine coalbed. Additionally, the probability of bump occurrence is increased by certain mining practices that concentrate stresses during retreat mining, in areas where geologic conditions are conducive to bumps. Mining plans that permit the development of pillar line points or long roof spans that project over gob areas should be avoided because these features may contribute to the occurrence of bumps.

Jan 1, 1987

By Charles L. Kusik

As part of an effort to establish processes that could be exploited in case of adverse changes in international chromium production and trading patterns, this study was sponsored by the Federal Emergency Management Agency (formerly the Federal Preparedness Agency) through the Bureau of Mines, to experimentally determine the feasibility of recovering chromium from critical scrap metals containing significant quantities of this element. Based on a conceptual pyrometallurgical chromium recovery flowsheet developed at Arthur D. Little, Inc., the experimental program described in this report demonstrated key process steps for the recovery of chromium as ferrochromium in a batch process. The process involves oxidation of chromium into a slag phase, subsequent separation of the slag phase from the remaining metal, followed by reduction of chromium from the slag phase to produce ferrochromium.

Jan 1, 1981

By T. J. Driscoll

In this Bureau of Mines investigation, the electrochemical polarization behavior of Fe and Fe-1BCr has been characterized in rigorously controlled 1[N] H2S04 solutions stirred with oxygen or an inert gas. Samples that under-went various levels of corrosion or passivation were examined using Auger electron spectroscopy (AES) and ion sputtering. Passivation of iron occurred at a potential of approximately 0.6 volt (1) in poorly stirred, oxygen-saturated solutions for forward polarization (scanning from cathodic to anodic potentials); (2) in pH-adjusted (increased), well-stirred, oxygen-saturated solutions for forward polarization; and (3) in well~ and poorly stirred, oxygen-and helium-saturated solutions for reverse polarization. Passivation of Fe-18Cr occurred at a potential of approximately -0.1 volt in helium-, nitrogen-, and oxygen-saturated solutions for all cases of forward polarization and most cases of reverse polarization. Elemental depth profiles obtained from AES sputtering measurements indicated that films or adsorbed species were present on iron samples in solution subjected to open-circuit, active, and transpassive corrosion, cathodic reduction, and passivation. This conclusion was reached by considering the distribution of the solution species, primarily sulfur, in the films, which were composed primarily of iron and oxygen. Sulfur was present throughout the films on actively corroding samples, in the outer regions of films of passive and transpassive samples, and on the film surfaces of open-circuit and cathodically reduced samples. For Fe-18Cr, sulfur was found on the surfaces of films on passive samples only, indicating that only the passive samples had films on their surfaces in solution. The films on electropolished and passive Fe-1BCr samples had the largest chromium concentrations, estimated to be approximately 45 at. pct, with less chromium in films of cathodically reduced, active, and open-circuit samples, in that order.

Jan 1, 1979

By Gordon L. Kinney

The only economically important mineral currently produced in Bangladesh was natural gas. Bangladesh was not a world? ranked producer of any mineral commodity, but the possibility of producing and exporting commercial amounts of liquefied natural gas (LNG) was being examined. Proved reserves of natural gas were sufficient to supply most of the country's industrial and domestic heating and electric needs and still support an export-oriented LNG plant. Other mineral production was of virtually no significance to the economy, although there were a few prospects for nonmetallic mineral development. Bangladesh continued to make economic progress during 1978 and into early 1979. Gross domestic product (GDP) at current prices rose from $6.6 billion in 1976-772 to $8.2 billion in 1977?78 and $9.3 billion in 1978.79.2 In fiscal 1979, the economic conditions were favorable until a severe drought hit most of the country. It W88 reported that conditions were the worst in 40 years, and 88 of July 1979, substantial crop losses were predicted. The agricultural sector accounts for over 53% of the GDP and about 75% of all employment. The poor weather will cause economic problems in the form of slower growth, larger trade deficits, and a higher rate of inflation. The 1978.79 statistics showed that real GDP increased just 4%.

Jan 1, 1981