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By Joseph C. Zelanko, Christopher Mark

During August, two eastern Kentucky coal miners died in a roof fall during retreat mining operations. They had just finished extracting one pillar block and were moving to the next one when the intersection they were standing in collapsed. Regrettably, this was not an isolated incident. Since the end of 2000, there have been 28 ground fall fatalities in U.S. coal mines. Of these, 10 occurred during pillar recovery operations. Although pillar recovery has been associated with about one third of recent ground fall fatalities, it accounts for only about 10% of U.S. underground coal production. Statistically, a coal miner engaged in pillar recovery is several times more likely to be killed in a ground fall than a miner on an advancing section of a longwall. Pillar recovery is dangerous because it creates an inherently unstable situation. Once the pillars are extracted, the roof is expected to cave. Safe pillar recovery does not mean preventing roof collapse, it means ensuring that it only occurs after the miners have completed their work and have left the area. Fortunately, there are a number of proven techniques that can greatty reduce the hazards of pillar recovery. These include better mine planning, improved roof support, and safer work procedures. The goal of this article is to describe the most significant "risk factors" associated with pillar recovery, and prescribe control techniques that, taken together, can reduce the overall risk to miners. The conclusions are based on extensive studies conducted by the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) that have included detailed analysis of every fatal retreat mining incident since 1992 (25 incidents resulting in 30 fatalities). Risk reduction strategies for pillar recovery can be divided into three main groups: Global Stability: Prevention of section- wide pillar failure; Local Stability: Prevention of roof falls in the working area; and Work procedures and worker location: Minimizing exposure to hazardous areas.

By A. E. Sands

The Bureau of Mines, S. Department of the Interior) at, its Morgantown., W. Va., station, operating under a cooperative agreement with West Virginia University, is conducting research and development work on the problem of producing synthesis gas from coal. An important part of this work is the study of the gas purification necessary to meet the rigorous standards required to render the gas suitable for use in the Fischer-Tropsch synthesis of liquid fuels. One of the most detrimental impurities is sulfur in all forms, the maximum amount that can be tolerated being one-tenth of a grain per hundred cubic feet. Concentrations as low as this require the use of precise analytical methods to evaluate the performance of processes used for removing sulfur. At the same time the analytical methods should be rapid in order to reveal the failure of purification before damage to the expensive synthesis catalyst results. Although sulfur in unpurified gas is generally present as hydrogen sulfide and as organic sulfur compounds, the latter may be converted to hydrogen sulfide for analytical purposes. Thus a suitable method for the determination of traces of hydrogen sulfide may also be used for the determination of organic sulfur.

Jan 1, 1949

By R. H. Nielsen

A new, cheaper precipitation scheme has been developed to produce purified zirconium oxide, Technical-grade sulfuric acid is used to precipitate a basic zirconium sulfate from a hot dilute hydrochloric acid solution. With close control of temperature, pH, and zirconium - sulfate ratio, excellent purification and complete zirconium recovery can be attained. The process has been successfully applied for 3 months and has proved to be a more satisfactory procedure than the ammonium phthalate process used previously. INTRODUCTION The Northwest Electrodevelopment Laboratory of the Federal Bureau of Mines has developed and improved the Kroll process for the production of pure ductile zirconium and hafnium. metal. Since 1946 over 1 million pounds of zirconium sponge metal has been produced, mostly high-purity material for the Atomic Energy Commission

Jan 1, 1956

By K. O. Bennington

The thermodynamic properties of hedenbergite, of composition [(Ca0,9516) (Mg0,0583Fe2+0.7134 Fe3+0.0934 Mn0,1366) (Si206)], were experimentally determined at the Bureau of Mines. The standard enthalpy of formation determined by hydrofluoric acid solution calorimetry is AHf298 = -680.96±0.855 kcal/mol. The standard enthalpy of formation from the oxides is AR-96 = -24.55±0.485 kcal/mol. Low-temperature heat capacities were determined by adiabatic calorimetry from 12.3 to 300.1 K. The derived standard entropy is S-98 - 41.218±0.148 cal/mol-K. High-temperature heat capacities were measured with a differential scanning calorim¬eter from 397 to 1,147 K. These experimentally determined data were combined with data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of measurements. Standard enthalpies of formation are given as a function of temperature. The standard Gibbs energy of formation at 298.15 K is AGf298 = -641.90±0.86 kcal/mol.

Jan 1, 1984

By John J. Henn

As part of the U.S. Department of the Interior programs on rutile, authorized by the Office of Emergency Preparedness in June 1967 under provisions of the Defense Production Act, the Bureau of Mines reviewed available literature on major proposed processes for producing rutile substitutes. The processes are grouped according to the major processing step, and important operating features are described. Sixty-one references are cited.

Jan 1, 1970

By Ralph V. Higgins

The present methods of appraising the long-range performance of oil reservoirs are based upon physical properties of the crude oil and the permeability of the reservoir rock. By means of these methods the performance of a reservoir may be estimated throughout its entire life. Before these methods were used, the future performance was estimated mostly by extrapolating pressure-decline curves -a method that is satisfactory for extrapolating only for a short period into the future. One factor that affects satisfactory long-range prediction of reservoir performance is the extent to which small changes in the physical properties of the oil and differences in the choices of relative permeability influence the calculated oil recovery. Selection of the physical properties of the samples to represent those of the oil and rock for the entire reservoir is difficult. This report is concerned with the error in calculated recoveries that may result from these inherent difficulties.

Jan 1, 1956

By Thomas Varley

"During the past few years, since flotation has become the paramount treatment method for most all kinds of ores, the Bureau has gathered the data on consumption of reagents used in the flotation treatment. The first report was issued in 1916. A brief review of such reports shows the progress made in the art of flotation, and each year brings forth development of new reagents or combinations of reagents that seem sure to survive, but research and progress spell their defeat, if not by entire elimination, at least subjects them to considerable modification. Fortunately, close cooperation between the Bureau and the operators has been the means of an exchange of ideas in research work, and the development, in plant practice, of such research work on a commercial basis, is one of the outstanding features in milling today.In past years flotation has been referred to generally as ""oil flotation""— today it might be more properly called ""chemical flotatioin"" Minerals can be floated today without oil. Chemicals alone will do the work, showing how little was truly known about the process heretofore. The term ""regents as used herein, includes both chemicals and oils. The total pounds of oils and reagents consumed during the year was greater than shown in the 1925 report. The 1926 total was 201,711,795 pounds as compared with 81,688,967 pounds for 1925. The equivalent in pounds of reagent use& per ton of ore for 1926 was 3.933 as compared with 1.7972 for 1925. This increase is due largely to the amount of lime which is added in the alkaline circuits particularly in the mills treating coppers ores, which accounts for the larger tonnages."

Jan 1, 1928

This surveillance report summarizes data on work-related fatal and nonfatal injuries, illnesses, and hazardous exposures in the mining industry for the 10-year period 1986-1995. The term "surveillance," as used in public health, may be new to many readers of this report. With regard to occupational safety and health, the goal of surveillance is to describe the occurrence of work-related injuries, illnesses, and known hazardous exposures; to identify new hazards that may occur due to the introduction of new technology or other factors; and to assess the effects of preventive measures designed to improve worker safety and health. Surveillance provides an overall picture, which can be used to focus resources on areas most in need of prevention programs or further research. Surveillance generally requires the use of multiple sources of data, all of which have their own strengths and limitations. Surveillance in the U. S. mining industry is complicated by the fact that U.S. national data systems that provide information on mining are based on two different definitions of the mining industry. One is established by the Mine Safety and Health Administration (MSHA), the other by the Standard Industrial Classification (SIC) System [Office of Management and Budget 1987] and the 1980 U. S. Bureau of the Census (BOC) Classification System [U.S. Bureau of the Census 1982]. The mining industry as defined by MSHA is based on the regulatory jurisdiction of that agency. Reporting requirements for injuries, illnesses, and workplace exposures are stipulated under the Federal Coal Mine Health and Safety Act of 1969 and the Federal Mine Safety and Health Amendments Act of 1977. Of note is that the oil and gas extraction industry falls outside of MSHA jurisdiction. The Occupational Safety and Health Administration (OSHA) was charged with enforcement in the oil and gas industry under the Occupational Safety and Health Act of 1970. Under the SIC, the definition of mining covers the extraction of naturally occurring minerals, including liquids (petroleum), gases (natural gas) and solids (coal, metal, and nonmetallic minerals). Exploration and development of mineral properties are also included in the SIC definition of the mining industry. The SIC was developed by the Office of Management and Budget for use in classifying establishments based on the type of economic activity in which they are engaged and serves as the industry classification standard for all establishment based Federal economic statistics. This classification is important for occupational safety and health surveillance because it also serves as the industry classification system for all data on work-related injuries and illnesses collected by the U.S. Bureau of Labor Statistics (BLS). The U.S. Bureau of the Census uses an industry coding scheme similar to that used by the SIC. For the mining industry, the categorization is identical in both systems. Death certificate data made available by the National Center for Health Statistics (NCHS) are categorized under this system. Death certificate data are particularly important for surveillance of mortality from work-related illnesses. Key differences between the SIC/BOC categorization system and the MSHA system can be summarized as follows: • MSHA excludes the oil and gas industry, which is classified as part of the mining industry under SIC/BOC. • MSHA excludes work that is done off of mine property; work off of mine property is included under SIC/BOC if it is performed by an establishment falling into one of the SIC/BOC mining industry codes. • MSHA includes mine-associated mills and processing plants; these are classified under the manufacturing industry, rather than mining, according to the SIC/BOC coding structure. Since the data collected by MSHA and the data collected by BLS and NCHS using the SIC/BOC classification system are both important sources of information on the mining industry and in many cases serve different purposes, data from both systems are presented in this report. In general, data using the SIC/BOC system are comparable across U.S. industries and should be used when comparing mining to other U.S. industries. Much of the data in this report are presented in the form of frequencies or rates. A frequency provides only a count of the number of cases without providing any information about the risk of occurrence. Rates provide an estimate of the risk of injury or illness. The reader is cautioned, however, that rates based on small numbers can be unstable; thus, any inferences should be drawn with care. In this report, no rates are presented for groups in which there were fewer than three cases. The incidence of most injury and illness conditions differs by age, sex, and race. For this reason, data in many surveillance reports are adjusted for these demographic factors. It was not possible to do this for most of the rates in this report because information on demographics was not available. With the exception of the proportionate mortality ratios (PMRs), all data presented are unadjusted. A detailed account of the sources of data is in appendix A. The methods used in data selection and analysis are described in appendix B.

Jan 5, 2000

By Lloyd H. Banning

Crucible-smelting tests at the Northwest. Electrodevelopment Laboratory and a pilot-plant test on electric smelting of western phosphate rock for the Westvaco Chlorine Products by the Tennessee Valley Authority indicated that the small vanadium content of the rock is concentrated in the ferrophosphorus by-product of Phosphorus smelting. This research is concerned' mainly with recovering vanadium and phosphorus froth the ferrophosphorus produced from western phosphate rock. Exploratory tests were made of several methods of treating vanadiferous ferrophosphorus. Attempts to separate vanadium as a carbide dross by saturating molten ferrophosphorus with carbon were unsuccessful. Volatilization of phosphorus from ferrophosphorus was accomplished to some extent, both with and without addition of sulfur in several forms, but elimination of phosphorus was not complete. Brief testing in a small experimental converter on oxidation of vanadium and phosphorus; into a slag by blowing with air showed promise. A method that comprised fusing vanadiferous ferrophosphorus mixed with soda ash under oxidizing conditions gave encouraging results and was tested beyond the preliminary stage. A slag product of the fusion contained most of the phosphorus and vanadium as water-soluble sodium phosphate and. virtually water-insoluble sodium vanadate. After leaching the sodium phosphate froth the slag, the leach residue was reroasted with soda ash and salt. This roasted product was leached again with water to extract the vanadium.

Jan 1, 1951

By Thomas E. Green

A combined solvent extract ion-spectrophotometric method for the determination of as little as 1 ppm of copper in tungsten metal or tungstic oxide has been developed and evaluated. Metallic samples are converted to tungstic oxide by treatment with hydrofluoric and nitric acids. The oxide is then dissolved in sodium hydroxide, and the copper is extracted as the colored neocuproine complex. Total elapsed time for the analysis is approximately 1-1/2 days; however, actual working time for a group of six or eight determinations is less than 4 hours. Precision at the 2-ppm level is better than 0.1 ppm.

Jan 1, 1963

By F. R. Cattoir

Analytical methods are presented in this paper for determining soluble titanium, total titanium, indicated titanium, and average effective valence in titanium chloride - sodium chloride mixtures. In addition, data are given showing the effects of coarse and fine grinding on the degree of oxidation and average effective valence of such samples. INTRODUCTION The Electrometallurgical Experiment Station at Boulder City, Nev., as part of the Bureau of Mines program to obtain more efficient utilization of our natural resources, has been developing and improving titanium extractive metallurgical methods and techniques since 1945. Numerous reports have been published describing development of the Kroll process,4/ the electrorefining technique,5/ and methods of analyzing titanium sponge.6/

Jan 1, 1957

By Donald W. Mitchell, John Nagy, Edwin M. Murphy

"Investigations in the Federal Bureau of Mines Experimental coal mine near Pittsburgh, Pa., have shown that high-expansion foam containing at least 0.2 ounce of water per cubic foot of volume is effective in controlling exper-imental underground coal, oil, or wood fires. Some of the fires were extinguished, but more of the coal and wood fires were brought under enough control to permit direct attack with water or other extinguishing agent or loading the hot material into cars. The largest controlled experimental fire, which burned about 5 hours before attack, was in a coalbed 5 feet wide, 10 inches thick, and 100 feet long. The greatest distance foam was transported to control a fire was 1,010 feet.An incipient fire should be attacked promptly with water, rock dust, or other approved and readily available extinguishing agents. Where heat, roof falls, and smoke prevent direct approach, the more involved procedure of using foam may be advantageous. The effectiveness of the foam in controlling a deep coated fire of considerable extent H,vet to be proved by actual trials in aSome hydrogen, carbon monoxide, and methane gases are generated when a fire is attacked with foam. Calculations showed that in experimental fire tests an explosive mixture could form; however, this would occur only within a narrow range of combustible gas-air mixtures not likely to be found in practice. The principal explosion hazards are due to generation of gases by the foam, localized build-up of normally liberated methane, and volatiles liberated by the coal during heating. The quantity of combustible gases generated by the action of the foam on the fire is about the same as that when an equivalent amount of water is applied."

Mar 1, 1960

By F. Keith Shelton

"INTRODUCTION Cobalt is an essential metal in the normal industrial ac¬tivity of the United States. Being an important constituent of high-speed steels and other cutting-tool materials, it becomes of critically essential importance during periods of national emergency. 3/ The Presidential order of December 20, 1940, included cobalt among other essential commodities that could be exported only under license. The Executive order 4/ listed cobalt metal, cobalt oxide, and alloys containing more than 5 per¬cent cobalt as being within the licensing requirements.There was no domestic marketed production of, cobalt products from 1931 until 1940 when the Pyrites Co. 5/ produced some cobalt oxide. The major portion of the domestic cobalt requirements has been obtained from Northern Rhodesia, the Belgian Congo, and French Morocco. 6/ The uncertainty of sea transportation from those sources of supply demanded that steps be taken to obtain from domestic raw materials an adequate supply of cobalt for use in the materials required for production of indispensable machined war metal products. In connection with the national policy for attaining self-sufficiency of strategic and critical materials, the Bureau of Mines, Boulder City, Nev., Experiment Station initiated studies to recover cobalt from the low-grade oxidized cobalt deposits in the Goodsprings district, Nevada. Hewett 7/ reported occurrence of cobalt specifically in the Blue Jay, Columbia, Copper Chief, and Highline mines and generally over a widespread area in the district."

Jan 1, 1946

By S. P. Sandoval

Several researchers have shown that the surface of chalcopyrite becomes hydrophobic under oxidizing conditions. Because dissolution of copper from chalcopyrite in dump leaching occurs under oxidizing conditions, the U.S. Bureau of Mines studied the effect of surfactants on chalcopyrite leaching under dump chemical conditions. Surfactants were selected for study because they can lower interfacial tension. The tests were conducted in shaking water baths using 250-mL Erlenmeyer flasks in statistical experimental design formats. The addition of nonionic surfactants increased copper extraction in the fernc sulfate leaching of chalcopyrite when sufficient Fe3+ was present. A positive interaction between Fe3l+ concentration and surfactant concentration was demonstrated. Copper concentration in the leachhing solutions was increased by as much as 100 pct at 25° and 50° C by adding nonionic surfactants. ionic surfactants decreased leaching. The structure of the nonionic surfactants and their hydrophile-lipophile balance (HLB) influenced surfactant performance. The branched hydrophile of an ethoxypolyol was beneficial to surfactant performance. The ethoxypolyol was the superior surfactant at 25° C, but became unstable at 50° C. Four surfactants, an ethoxyalchohol and three block copolymers, performed best at 50° C.

Jan 1, 1990

By Edmund S. Leaver

The Precious Metals Section is concerned primarily with ore-testing problems associated with precious metals and with the analysis and concentration of a large number of the strategic-mineral samples that have been included in the research program of the Bureau of Mines. During the fiscal year 1938-39, 30 projects were completed. The requests for this service are based upon the desire of the sponsor to obtain the best or most satisfactory method for maximum recovery of the minerals. In many instances it is a question of improving present milling practice, with due regard to utilization of present equipment. In others, the probable tonnage available maybe the deciding factor in the choice of a particular recovery method. Under all circumstances the results of tests axe prepared with the thought of aiding a competent metallurgist, familiar with local conditions, to formulate a practical flow sheet or to assist the mill operator to correct known losses. A microscopic examination for identification of the mineral constituents and their association in each ore is always a big help, in planning the tests and may indicate the reason for former troubles or assist with best procedure.

Jan 1, 1940

By Edmund S. Leaver

The Precious Metals Section is concerned primarily with ore-testing problems associated with precious metals and with the analysis and concentration of a large number of the strategic-mineral samples that have been included in the research program of the Bureau of Mines. During the fiscal year 1938-39, 30 projects were completed. The requests for this service are based upon the desire f the sponsor to obtain the best or most satisfactory method for maximum recovery of the minerals. In many instances it is a question of improving present milling practice, with due regard to utilization of present equipment. In others, the probable tonnage available maybe the deciding factor in the choice of a particular recovery method. Under all circumstances the results of tests axe prepared with the thought of aiding a competent metallurgist, familiar with local conditions, to formulate a practical flow sheet or to assist the mill operator to correct known losses. A microscopic examination for identification of the mineral constituents and their association in each ore is always a big help, in planning the tests and may indicate the reason for former troubles or assist with best procedure.

Jan 1, 1940

By L. R. Fisher

The purpose of this investigation was twofold: (1) To devise a rapid method for determining quantitatively the porphyrin-carboxylic acid content of a particular crude-oil porphyrin aggregate, and (2) to isolate porphyrins in the crystalline state from crude-oil porphyrin aggregates. The first purpose was accomplished by applying adsorption chromatography. In fulfillment of the second aim three different crystalline porphyries were isolated by methods which involved both adsorption chromatography and fractionation of benzene solutions with hydrochloric acid of varying strength. The three porphyrins had etio, rhodo-, and phyllo-type absorption spectra, respectively. INTRODUCTION Many samples of petroleum have, as interesting minor constituents, chemical compounds known as metalloporphyrins. Their presence in crude oil and other bituminous materials was first discovered by Treibs a quarter century ago. Much experimental work has been done on metalloporphyrins because of their importance to the petroleum industry. They have a deleterious effect on refining catalysts. The ash resulting from the burning of heavy fuel oil is very reactive, We to the presence of metallic constituents, particularly vanadium. In oil-fired gas turbines, the ash may build up on the blades, causing imbalance of the rotors and, in addition, severe corrosion. In industrial boilers, the ash residue is responsible for severe damage to boiler tubes and to the refractory brickwork (15).4 Through study of the chemical constitution of the various metalloporphyrins found in petroleum, much can be learned concerning the origin, migration, and history of crude oils.

Jan 1, 1961

By A. Gene Collins, Cynthia A. Pearson, Cathy J. Waters

The chemistry of selenium and tellurium is discussed , along with a method of preparing a synthetic oilfield brine , an oilfield brine sampling method , and methods for determining selenium and tellurium in complex oilfield brines . Selenium either can be reduced to the elemental form with sulfur dioxide and determined semiquantitatively by color comparison of the red amorphous form or can be converted to selenite and determined quantitatively by reacting it with 3,3 ' - diaminobenzidine and obtaining its spectral absorbance at 420 mu . Tellurium can be reduced to the elemental form with hypophosphorous acid , and the spectral absorbance of its red hydrosol can be measured at 400 mu . Less than 0.05 mg / 1 of selenium and 0.1 mg / 1 of tellurium can be determined by the described methods .

Jan 1, 1964

By George L. Gates

The Bureau of Mines developed a rapid instrumental method of analyzing oil well scales containing primarily barium sulfate. After removal of oil and water by carbon disulfide) the scale was dissolved in strong hydrochloric acid. The cations, barium, calcium, strontium, magnesium, and iron, were determined with the flame photometer using the method of additions. Sulfate was deter-mined colorimetrically after separation by selective adsorption on an alumina column. Phosphate was determined colorimetrically and carbonate titrimetrically. The method was reasonably accurate, although iron and magnesium were found to have mutual interference.

Jan 1, 1965

By A. Gene Collins

This report discusses some of the chemistry and geochemistry of cesium and rubidium. Knowledge of the cesium and rubidium content of oilfield waters aids in resolving the origin of waters and petroleum, exploring for petroleum and other valuable minerals, discovering water pollution sources, and augmenting the knowledge of geologic formations. The methods described in this report permit the detection of less than 0.01 mg/l of cesium and/or rubidium in a complex oilfield brine or water. Solvents possessing high-dielectric constants were evaluated for their ability to extract cesium and rubidium tetraphenylboron from oilfield waters and for their flame emission characteristics. Nitroethane was selected and used for the extraction and flame spectrophotometric determinations because it gave the highest sensitivity. Cesium 137 and rubidium 86 were used to determine the extraction efficiencies, which were about 87 percent and 58 percent respectively using a single 10 ml nitroethane extraction from a distilled water matrix. The standard deviation of the determination was 0.0008 mg for cesium and 0.0007 mg for rubidium in the 0.01 mg range.

Jan 1, 1965