Search Documents

By M. L. Wang, S. R. Short, E. M. Daniloff, E. L. Petsonk, D. M. Mannino, G .. R. Wagner

"Background—It has been suggested that health related job selection is a major cause of the healthy worker effect, and may result in inaccurate estimates of health risks of exposures in the working environment. Improved understanding of self selection, including the role of airway hyperresponsiveness, should improve accuracy in estimating occupational risks.Methods—We evaluated symptoms of the respiratory tract, lung function, occupa¬tional and smoking histories, and airway responsiveness from a cross sectional sur¬vey of 478 underground bituminous coal miners and non-mining controls. Workers with abnormal spirometry were excluded from methacholine testing.Results—Methacholine responsiveness (= 15% decline in forced expiratory volume in one second) was associated in both miners and controls with reduced ventilatory lung function and an increased risk of respiratory symptoms. Miners with the longest duration of work at the coal face had a low prevalence of methacholine responsiveness, compared with miners who had never worked at the coal face (12% v 39%, P < 0.01). Throughout their mining careers, miners who responded to methacholine were consistently less likely to have worked in dusty jobs than miners who did not respond to methacholine.Conclusions—These results provide evidence that workers who are employed in dusty jobs are less likely than their unexposed coworkers to show increased non-specific airway responsiveness, pre-sumably as a result of health related job selection. Surveys of workers in which responsiveness data are unavailable may underestimate the effects of dust exposure on respiratory health."

Dec 1, 1996

By J. J. Drost

The feasibility of basic oxygen furnace (BOF) offgas heat recuperation by preheating scrap was investigated on a pilot plant scale by the Bureau of Mines. In this study, offgases generated during the oxygen blowing of a molten pig iron and scrap charge were passed through a static bed of shredded auto scrap. Scrap quantities varying from 100 to 180 pounds and representing from 22 to 40 percent of the 450-pound BOF metallic charge were preheated in this manner. Average scrap bed temperatures of 1,650° F for 100 pounds of scrap and 1,150° F for 180 pounds of scrap have been achieved during the blows. As compared to cold scrap used in the normal BOF practice, it was found that by preheating scrap, usage could be increased by 43 percent. The thermal energy recovered by this preheating method can account for up to 44 percent of the energy necessary to melt the scrap.

Jan 1, 1974

By J. M. Kuchta

The Bureau of Mines investigated four simulated coal gob fires to obtain a more reliable data base for defining the state of a sealed mine fire and to evaluate the performance of various fire detectors. The fires were conducted in a multiple-entry section of the Bruceton Experimental Mine by heating 4,000 to 21,000 pounds of rubblized bituminous coal to ignition and monitoring the temperature, gas emissions, and smoke under ventilated and sealed combustion conditions. Product gas concentrations depended upon the coal bed size, coal temperature, heating rate, and oxygen concentration or ventilating condition but varied little after the fires were sealed. Expressions are given that define the temporal variation of CO and O2 after sealing when the coal temperature decreased rapidly. The CO/C02 ratio is a more sensitive fire indicator than the CO/?02 ratio, although the latter is universally used for detecting the incipient state of a coal fire. In comparison, the Jones-Trlckett ratio [ CO2 + ¾ CO ? ¼ H2 ?O2] is less reliable for this purpose. The best detector for determining the state of a mine fire after it has been sealed was a prototype submicrometer smoke particulate sensor. Limitations of the various detector systems are also discussed.

Jan 1, 1982

The strike of the Canadian asbestos miners entered its seventh month with increasing signs of early termination. Both unions are in the midst of heavy negotiations with management, and an optimistic industry source predicted that work would resume by October 1. Recession recovery in some segments of the asbestos manufacturing industry is being impeded by lack of fibers, CADMIUM - On September 9, St. Joe Minerals Corp. reduced the price of cadmium metal to $2.75 per pound. The producer price bad been uniformly quoted at $3.00 per pound since June 26, 1975. Subsequently, Amax, Inc. and National Zinc Co. reduced their prices to $2.50 per pound. By mid-September all five U.S. cadmium producers were marketing the metal at $2.50 per pound.

Jan 1, 1975

By Brian R. Zelenka

The Bureau of Mines (Bureau) reviewed all available information regarding geologic and depositional processes contributing to potential coastal and offshore platinum group metal (PGM) placer deposits around the Goodnews Bay Mining District. The Bureau found that favorable environments for PGM along with gold and chromite enrichment include: (1) buried paleofluvial channels; (2) recent paleofluvial channels with little marine sediment overburden, (3) beach deposits, particularly in the upper swash zone and near back beach environments; (4) paleostrand lines; (5) shoal lag deposits inside the mouths of Goodnews and Chagvan bays; and (6) bases of far offshore tidal ridges which may represent reworked glacial deposits. Limited geologic and compositional (assay) data prevent determination of deposit size and grade of PGM mineralization for each deposit class. Future geologic sampling requirements for demonstration of identifiable offshore and beach PGM-bearing placers are discussed. Beach and offshore sampling programs conducted by the Bureau in 1986 will contribute additional information providing verification of specific deposit classes.

Jan 1, 2011

In 2005, data obtained from the Mine Safety and Health Administration (MSHA) indicated a total of 922 underground (6.3%) and 13,744 surface (93.7%) mining operations.1

Jan 1, 2008

By B. E. Blair

The physical properties and related geological and petrographic data for 81 rock types obtained from operating mines or selected test sites are presented in this report. Most of these rock data were obtained to supplement structural studies in underground mines; however, the data may be equally applicable to other problems where the physical properties of rock are an important factor. Stress-strain curves are presented, where available, and free medium velocities from laboratory and field measurements are compared for several rock types. Rock-type, geographical, and geo-logical indexes are included for reference relative to physical property data in this and previously published Bureau of Mines physical property reports. INTRODUCTION This report presents the physical properties of 81 rock types from 16 different projects (sections 53-68). Three previous physical property reports2 3 4/ (herein after referred to as parts I, II, and III) presented data on 244 rock types from 52 project areas. (Part I included sections 1-25, part II sections 26-36, and part III sections 37-52).

Jan 1, 1956

By James Westfield

This publication covers the work of the Division of Coal Mine Inspection, Bureau of Mines, as performed under provisions of the Federal Coal Mine Safety Act. It presents background information and data since 1952 when the Act became effective and includes up-to-date statistics for the calendar year 1962. During that year, approximately 9,704 coal mines were active in the United States, and the Bureau made 12,810 regular inspections. BACKGROUND The Federal coal-mine inspection program was established to carry out the provisions in Public Law 49, 77th Congress, (H. R. 2082) approved May 7, 1941. This act has since been amended as Title I, Advisory Powers Relating to Health and Safety Conditions in Mines, under Public Law 552, 82d Congress, approved July 16, 1952, which also included Title II, Prevention of Major Disasters in Mines. Public Law 552 is known as the Federal Coal Mine Safety Act.

Jan 1, 1963

By Jennifer Riefenberg

The U.S. Bureau of Mines has long recognized the hazards associated with rock burst activity in underground mines. Concern over lost lives and resources prompted this study to further characterize rock burst occurrence as related to microseismicity and mining. A period of over 1,079 days of mining with 101 bursts, where microseismicity rates and blasting were recorded, was used in this study. Statistical analyses investigated relationships between (1) rock burst occurrence versus blasting, (2) rock burst size versus damage, (3) rock burst occurrence versus average micro seismicity rates, and (4) rock burst occurrence versus local mine geometry. Statistical analyses showed that 91% of all rock bursts occur with blasting while only 3% of all rock bursts occur, apparently, independent of blasting. Additionally, the long-term average daily micro seismicity rates appear to dictate when blasting will trigger rock bursts. Time series analysis on the daily microseismicity resulted in model equations that may be used to forecast the daily microseismic activity.

Jan 1, 2010

By H. P. LeVan

Research was conducted to examine the feasibility of extracting manganese from Georgia umber ore by a three-stage continuous sulfuric acid-ferrous sulfate pickle liquor leaching process. A continuous cyclic process for treating the umber was operated successfully, using a synthetic solution simulating a ferrous sulfate fortified anolyte solution discharged from a manganese electrolytic cell as the leaching medium. Leaching efficiency based on removal of the manganese from the ore ranged from 83 to 89 percent for all systems tested.

Jan 1, 1965

By C. M. Frost

The hydrodesulfurization characteristics of a residual fuel prepared from Wilmington, Calif., crude oil were determined at temperatures from 600° to 900° F, pressures of 200 to 800 pSig, and space velocities from 0.2 to 2.0 Vo/Vc/hr, using cobalt molybdate type catalysts. A prediction equation, developed from the experimental data, satisfactorily predicts the fraction of total sulfur that can be removed under any combination of operating conditions within the ranges investigated. Yields and properties of the low sulfur product are correlated with the fraction of total sulfur removed. Kinetic calculations show that the apparent reaction order and activation energy change with space velocity and temperature.

Jan 1, 1970

By W. Hermanson

This report presents the results of a task to complete a final design of a remote controlled hi-roof bolting machine for high roof areas in coal mines. The project was begun by visiting several coal mines to become familiar with roof fall areas. Several machine concepts were generated and presented to the design committee for criticism. A preliminary design was completed, as covered by this report. A Final Design and Final Report will be issued incorporating the committee comments at the Preliminary Design review and comments received concerning this Preliminary Design Report.

Jan 1, 1979

By W. W. Adams

"The results of the fourth annual safety contest, 'mown as the National Safety Competition, contacted by the United States Bureau of Mines are herein announced. A bronze trophy, ‘Sentinels of Safety’, the gift of the Explosives Engineer magazine, has been awarded to the leading mine in each of the five groups into which the mines and quarries that participated in the contest were arranged. These five groups were: anthracite mines, bituminous coal mines, metal mines, nonmetallic-mineral mines, and carries and open-pit mines. The leading plant in each group was the mine whose employee lost the smallest number of days from accidents in proportion to the total number of man hours worked. Where two or more mines operated without a lost-time accident, the winner was adjudged to be the plant which operated the largest number of man hours during the year.The contest was based upon reports of accidents and exposure sent by the competing companies to the Bureau of Mines. Records of the five leading companies in each group were made known to a Committee of Award, consisting of the following seven members: H. Poster Bain, Secretary of the American Institute of Mining and Metallurgical Engineers; James F. Callbreath, Secretary of the American Mining Congress; W. H. Cameron, Managing Director of the National Safety Council; H. L. Gandy, Secretary of the National Coal Association; A. T. Goldbeck, Director of the Engineering Bureau of the National Crushed Stone Association; William Green, President of the American Federation of Labor; and A. J. R. Curtis, Assistant to the General Manager of the Portland Cement Association. Members of the committee voted for the winning company in each group in accordance with the rules governing the contest.. A majority vote prevailed."

May 1, 1929

By Doss H. White

In 1989, Alabama&apos;s nonfuel mineral industry produced a State record of $463 million of nonfuel mineral commodities, an increase of $4 million over that reported by the State&apos;s mineral producers in 1988. The new record marked the fourth consecutive year in which mineral production increased over that of the previous year. Alabama ranked 22d among the States in total mineral value. Cement, stone, and sand and gravel were the three leading mineral commodities produced, accounting for 77% of Alabama&apos;s total mineral value. During the year, there were several acquisitions by Alabama cement and stone companies, and the only tantalum mine in the United States completed its first full year of operation.

Jan 1, 1991

By R. P. Vinson

The Bureau of Mines evaluated two real-time light-scattering dust monitors by measuring their response to Pittsburgh Seam coal dust and Arizona road dust (ARD). Both monitors, the model PDS-l, a personal dust sensor, and the model PCD-l, a digital dust indicator, are made in Japan by Sibata Scientific Ltd. Tests were conducted inside a laboratory aerosol chamber designed to maintain a uniform spatial distribution of the test dust. PDS-l and PCD-l measurements of concentrations for each test dust were averaged over 4-h test periods and compared with simultaneous gravimetric measurements. Both dust monitors responded linearly with mass concentration with both coal dust and ARD. However, the linear response of the PDS-l differed from that of the PCD-l for both dusts.

Jan 1, 1987

The revised inspection standards or recommendations herein have been prepared for use in Federal inspection of bituminous-coal and lignite mines. They succeed a compilation of similar standards published as Bureau of Mines Information Circular 7268 in December 1943 and employed as a guide in Federal inspections since that time. Important alterations and additions have been made because of changes in mining, practice and temporary shortages of some safety equipment; moreover, several previous standards have been found not generally applicable and have accordingly been deleted. Mining methods and equipment continue to change, and new hazards and new safeguards are introduced. Consequently, these standards are subject to revision from time to time. Questions from the coal-mining industry regarding these standards and suggestions as to changes and additions thereto will be welcomed and considered carefully when the next revision is made. Many constructive criticisms from the mining industry have been considered in preparing this edition.

Jan 1, 1945

By M. H. Marvin

This report presents the results of a program to develop backfilling techniques to mitigate undesirable effects of hydraulic borehole uranium mining. Large underground cavities, formed during the borehole mining process, can be backfilled to prevent ground subsidence and to allow mining of adjacent uraniferous sandstone. Three backfilling techniques were tested in the laboratory and in the field: bulk dumping of slurry into the borehole from ground level, slurry injection under water, and slurry injection above the cavity water level. These techniques were tested with sand and with sand and one percent cement (by weight) mixtures. The project was accomplished in four tasks: equipment preparation and transport, mining operation to generate a full-sized cavity, backfilling operation, and assessment through core samples and subsidence checks. The concentrations of cement mixed with sand proved to be inadequate to bond the sand. Bulk dumping resulted in a 30-degree angle-of-repose, much too steep to completely fill the cavity. Both slurry injection techniques filled the cavity satisfactorily. However, underwater injection is the recommended backfilling technique because the borehole water level does not need to be pumped down during backfilling. The borehole itself was filled by bulk dumping of slurry. In conclusion, backfilling of borehole mining cavities is entirely feasible, and the preferred method is slurry injection under water.

Jan 1, 1979

By Gary L. Hundley

The Bureau of Mines has devised and demonstrated an ammoniacal sulfate leach process for recovering nickel and cobalt from low-grade domestic laterites. Solvent extraction of cobalt, one of the process steps, requires the reduction of hexammine complexes of C03+ to C02+ in an ammo-niacal leach solution. Previously, reduction was accomplished using cobalt metal shot in a column. This report presents experimental results and an economic evaluation comparing two alternate techniques with the shot column: (1) an electrolytic reduction cell with an extended surface area cathode and (2) direct electrowinning from purified leach solution using a cell with a fluid bed cathode. The second alternative eliminates the conventional solvent extraction-electrowinning steps. The costs of the three methods, based on the requirements of a pro-posed commercial-sized plant, including all unit operations, were deter-mined by the Bureau&apos;s process evaluation group. The operating costs for the shot column, $1.19/kg Co, and for electrolytic reduction, $1.20/kg, are essentially the same, but the cost of direct electrowinning, $3.77/ kg Co, would eliminate this method as a practical alternative. The cap-ital cost of approximately $14.4 million for reduction in a shot column is much higher than the approximately $4.4 million for electroreduction.

Jan 1, 1985

By P. M. Sullivan

This report describes a new application of electroamalgam metallurgy in recovering all the zinc as refined metal from galvanizers&apos; sal skimmings. Pure zinc was recovered by electrolysis of skimmings leach liquors in amalgam cells. The following information was gained as a result of literature studies and subsequent laboratory investigations. 1. Reports in the literature indicate that pure zinc can be recovered from chloride solutions with the aid of amalgam cells. From Europe it was reported that amalgam cells could be used to recover pure zinc and chlorine from leach liquor obtained from pyrite cinders following a chloridizing roast.

Jan 1, 1956

By Thomas C. Atchison

The purpose of this Bureau of Mines investigation was to measure the amplitude and shape of the strain pulse and the size of the crushed zone produced in a granite by different explosives and to determine how these quantities are related to the detonation properties of the explosives. The reflection theory of rock breakage has shown that the amplitude and shape of the strain pulse incident at a free surface determine the fragmentation and volume of rock broken. Determination of the properties of an explosive that control the characteristics of the strain pulse produced in the rock will help in evaluating explosives for use in blasting. The investigation showed the different explosives produced a twofold variation in the amplitude of the strain pulse but little variation in the shape of the pulse. The explosives also produced a twofold variation in the volume of the crushed zone, but differences among the explosives were more accurately determined by strain-amplitude measurements than by crushed-zone measurements. The peak amplitude of the strain pulse and the volume of the crushed zone correlated with the calculated detonation pressure of the explosive.

Jan 1, 1959