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By Robert W. Freedman

Vacutainers are employed by the Bureau of Mines and the Mining Enforcement and Safety Administration for sampling mine air and other atmospheres containing fixed gases, low-molecular-weight hydrocarbons, and products of combustion. Tests were conducted to study shelf life of evacuated samplers prior to sampling and also to check the stability of sampled gases prior to analysis. An unexplained phenomenon, slow accumulation of carbon monoxide in evacuated samplers, occurred after a few weeks' storage; levels were low but increased with time and could pose a problem for critical applications. Accordingly, attempts to halt CO release by additional means of treatment were made, and storage at low temperature was found to be effective.

Jan 1, 1978

By P. J. McDonough

The Bureau of Mines designed and tested a hardware-software system for measuring on-line corrosion rates of materials in a rod mill in operation. Currents ranging from 10-6 to 10-3 A and potentials in I-mV increments were converted to a digital signal. The digitized data were frequency-modulated and transmitted from a rotating ball mill to an FM receiver, where they were decoded by computer and then processed in real time using assembly language software. This design approach would allow accurate measurement and control of systems where signals of small amplitude and large ranges are present.

Jan 1, 1988

By Lars Osen

The Bureau of Mines investigated (1) the effect of torsion on yield and ultimate strengths of bolts when the torsion is applied first and tensile load is applied independently of torsion and (2) various methods of increasing the tension-torque ratio and/or narrowing the data spread of the tension-torque relationship. A special torsional attachment was fabricated to attach to a universal testing machine to independently subject rock bolts to combined tensile and torsional loads. It was found that initially installed torsion is nullified during tensile loading and the tensile yield and ultimate strengths are not significantly reduced. Lubricating various components of a bolt assembly or using hardened washers will improve the tension-torque relationship during conventional installation; however, the torsional load is not nullified during this type of loading. Hence, a bolt is subjected to a combined stress throughout the loading cycle; the yield point will thus be lowered compared with the pure tensile yield if care is not taken during installation to stay below the torsional yield.

Jan 1, 1966

By Robert B. Fulton

Summary of data and estimates for 52 fluorspar properties in the following 13 foreign countries: Mexico Thailand China (PRC) Morocco Tunisia Italy Spain South Africa France United Kingdom Kenya Namibia Federal Republic of Germany Data includes deposit type, resource tonnage and grades, mining and beneficiation methods, annual production, fluorspar products and by-products, manpower requirements, capital and operating cost estimates. For operating properties, engineering and cost data have been developed for present and anticipated levels of production. Hypothetical operations have been assumed for undeveloped deposits.

Jan 1, 1984

By J. M. Mutmansky, L. Xu

"This paper outlines the results obtained when sampling twenty underground coal mine sections, each in a different mine. The sampling effort was oriented toward a detailed characterization of coal mine dusts and thus eight-stage Anderson Model 298 impactors were used as the primary collection instrument. This instrument allowed a rather detailed size distribution for each of the particulates sampled. Because four of the mines used diesel outby equipment and/or diesel shuttle cars at the face, it is possible to make some comparisons on the particulate distributions in diesel versus non-diesel mines.One of the more interesting results is the pattern that exists in mines that contain only diesels used for outby utility haulage. Particulate in these mines seem to be consistently heavy in the fine size ranges, perhaps being of significant concern to the industry. While no definite conclusions can be achieved from the limited data collected in this study, the data indicates that more detaile~ study of particulates in diesel mines is needed so that some idea of the particulate loadings in diesel mines can be achieved."

Jan 1, 1988

By Ronald M. Van Noy

A reconnaissance study of kyanite-group mineral deposits in the Northwest has revealed large exploitable reserves of the mullite-forming raw materials in the Woodrat Mountain and Goat Mountain districts of north-central Idaho. Potential coproducts or byproducts are garnet and muscovite mica. The Woodrat Mountain district contains garnet-kyanite-mica schist, which has been traced for 6 miles and may extend farther. Surface samples average 29 percent kyanite and contain up to 15 percent garnet. Inferred reserves of strippable ore with a low waste-to-ore ratio, and containing more than 15 percent kyanite, are more than 3 billion short tons. The Goat Mountain district contains several kyanite-mineral zones. Samples of the richest zones average from 10 to 20 percent kyanite minerals and represent about 200 million short tons of strippable rock. Beneficiation tests indicate that the kyanite minerals and garnet can be concentrated by a combination of gravity, flotation, and electromagnetic methods. Reserves in these deposits are sufficient to satisfy any foreseeable domestic and export demand. However, the freight tariff to reach the nearest major users of kyanite (located in the Midwest) has discouraged development of western kyanite resources. Western demand of a magnitude to support a moderate to large milling operation has not yet been developed. However, there is some foreign market potential. If a garnet byproduct could be prepared and sold for coated abrasive products or as grinding grains, an offset possibly could be gained to a por¬tion of the mining and milling costs for the Pacific Northwest producer. Such byproduct values would offer a means for expanding the geographic market areas as well as the regional market potential.

Jan 1, 1970

By B. J. Arnold, F. F. Aplan

"The captive bubble and sessile drop contact angle techniques have been used to evaluate the hydrophobicity of petrographically identified coal macerals. The magnitude of the contact angle on vitrinite is shown to be a function of coal rank ( %C, %0 and % vitrinite reflectance), increasing with increasing rank to a maximum for low volatile bituminous rank coals then decreasing for anthracite. The least data scatter is found when vitrinite reflectance is used as a rank parameter. Contact angles measured or estimated for other discrete macerals, indicate a variation in hydrophobicity based on coal type. These data correlate well with known flotation results. Coal is a heterogeneous mixture of plant remains and associated minerals that have undergone chemical and physical changes by biological and geological processes. These plant remains form coal macerals, discrete organic entities in the coal which have characteristic chemical and physical properties. As the differing chemical nature of each maceral will affect its behaviour in processes such as carbonization the separation of macerals during coal preparation may provide an important asset in coal utilization.Separation of some of the macerals based on specific gravity has been achieved in the laboratory, and by Sun and Cohen , in a study of two Pennsylvania bituminous coal preparation plants. It was indicated that the lighter exinites report almost exclusively to the clean coal while the denser inertinites are concentrated in the higher gravity fractions. The Longwy-Burstlein process6 took advantage of the difference in hardness or friability of the macerals by using impact breakage followed by screening to remove the more friable vitrain,clarain and fusain. The remaining durain, often high in spore content, was then recrushed. The re-mixed fractions produced the optimum size for obtaining the best coke strength for a particular coal.Separation or concentration of rnacerals by froth flotation largely depends on differences in the hydrophobicity of the macerals. Sun and Cohen 5 . indicated an order of decreasing floatability as exinite, vitrinite and inertinite, while a Russian study (as cited by Brown 7 ) showed that vitrains floated more readily than the duller types. More recently, Hirt and Aplan8 showed that 'pseudovitrinite' floats somewhat faster than does vitrinite while fusinite floats very slowly. Olson and A plan found that vitrinite floated easily while substantial quantities of the non-floated coal contained fusinitic material. Burdon noted that vitrinite is more floatable than semifusinite, and Sarker et a/. 11 have shown that vitrinite is selectively concentrated by froth flotation and oil agglomeration. Sun indicated that flotation, based on his calculated floatability index, should decrease in the order clarain, vitrain, fusain and durain; while Horsley and Smith 13 indicated the decrease to be: vitrain, clarain, durain and fusain. These differences can be attributed to the specific coals used in each study and to the individual macerals composing each coal type within a given coal."

Jan 1, 1989

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 J. S. Gomer

The U.S. Bureau of Mines conducted Cu exchange tests for six common clays under simulated in situ leaching conditions. Regression equations were obtained from the data expressing the Cu exchange capacity as a function of Cu concentration, pH, and temperature. Using these equations, an analysis was made of the impact each clay could have on overall Cu recovery. The results suggest that Ca and Na montmorillonite clays could have a major impact on Cu recovery and that attapulgite and illite clays could have a smaller, but still significant, impact. Kaolinite and ripidolite clays pose little threat to loss of Cu from in situ leaching solutions.

Jan 1, 2010

As part of the Phase I study activity, a questionnaire was sent to a representative sampling of mining companies to obtain information on the uses, use conditions, personnel policies and other user concerns associated with front-end loaders. On-site visits to several of the mining companies were also parried out and the questionnaire was used during these visits as well. Five major areas were dealt with in the user questionnaire. These included: 1) Front-End Loader Critique - An open-ended form was employed to permit the mining companies to describe the particular things they liked and disliked about front-end loaders, in general, and/ or specific models in particular. 2) Usage - A form indicating the functions performed by front-end loaders and the numbers, makes and models of front-end loaders being used by mining companies. 3) Environment - A form where the user indicated the various types of conditions encountered in their use of front-end loaders. 4) Personnel - A form for describing factors pertaining to the qualifications of front-end loader operators. 5) Miscellaneous and Comments - A form permitting the user to comment on his feelings toward standardization of front-end loader operator stations.

Jan 1, 1973

Table 1.-Aden: Production of mineral commodities [ ]

Jan 1, 1967

By John J. Sammarco

Light-emitting diodes (LEDs) are emerging as viable replacements for incandescent (INC)-based cap lamps used in mining. The photometric and energy characteristics of these light sources differ in important ways. This paper describes the performance of LED and INC sources in cap lamps in terms of correlated color temperature, color rendering, light output, electric power, ambient temperature and air flow, and light source aging. Importantly, these characteristics can influence a miner?s ability to spot mining hazards thus impacting safety. Second, some of these characteristics interact with the operating life of the cap lamp?s battery power, such that differences between LED and INC sources can be magnified toward the end of a 10-h battery discharge cycle. Empirically, we have determined that after 8 h at an ambient temperature of 25 ?C, the average light output of an INC cap lamp can decrease to about 69% of its initial value when powered by a lead-acid battery, and it can decrease to about 65% of its initial value when powered by a nickel-hydride battery. An LED-based cap lamp using a constant current drive circuit can maintain about 96% of its initial value when powered by a nickel-hydride battery. Real-world tests addressing the effects of ambient temperature and air flow on the light output of an LED and INC cap lamp were conducted in the National Institute for Occupational Safety and Health Safety Research Coal Mine. The LED cap lamp yielded a vertical average illuminance improve­ment of approximately 9.5%, and the INC cap lamp yielded a vertical average illuminance degradation of approximately 4%. The differences between LED and INC cap lamps were further quantified by the calculation of ?mesopic luminance? data that indicated for the same photopic luminance (i.e., as measured using a conventional light meter) the LED cap lamp could be up to 38% more efficient than the INC cap lamp with a lead-acid battery at the end of the 10-h driving cycle. Lastly, accelerated life tests were used to empirically determine light output depreciation as the INC light source age approached its useful life. There was about a 35% decrease in light output. This is quite considerable, particularly given that the light output will decrease an additional 30% to 45% over the period of a 10-h shift. The implications of the differences between LED and INC sources are discussed. This information is crucial in determining how visual performance could be affected for real-world conditions where batteries discharge during the work shift and as the light source ages. To date, only idealized conditions have been used for LED and INC cap lamp visual performance research.

Jan 1, 2009

By Launa G. Mallett, Charles Vaught, Dana C. Reinke, Lisa J. Steiner, Lynn L. Rethi, Kathleen M. Kowalski-Trakofler, Jr. Brnich, William J. Wiehagen

Safety and health professionals recognize that training is a critical element of any effective safety and health program. An extensive literature survey has led the authors to conclude that we are at the beginning of a revolution in training due to changes in the demographics of the workforce, the rapid growth of technology, and the universal ascendance of the information age. Of present major concern in the mining industry is how to provide appropriate training for an aging workforce and concurrently develop training for the expected influx of new and less experienced miners as older workers retire. This report explores the key issues in the changing safety and health training area as identified by the multidisciplinary team of NIOSH researchers who conducted the literature survey. Issues include generational differences between newer mine workers and the present workforce with respect to their physical, psychological, social, and cultural characteristics; their learning styles and work expectations; and the impact of technology. Some preliminary conclusions are offered for future training needs.

Jul 1, 2004

By R. D. Rosenkranz

The Bureau of Mines has investigated the availability of copper from 272 deposits in market economy countries. The deposits studied have demonstrated resources totaling 413 million metric tons of contained copper and account for more than 90 pct of the reserve base for market economy countries. Using data gathered as part of its Minerals Availability Program, the Bureau performed geologic, engineering, and economic evaluations in order to determine the copper production potential of each deposit. At the 1981 copper market price of $0.85/lb, the deposits studied could economically produce an estimated 88 million metric tons of copper (allowing for profit computed at a 15-pct rate of return), primarily from mines operating at the time of the study (1981). At this price, producing mines in market economy countries could economically produce only 2.1 million metric tons of refined copper per year. However, actual 1981 production was 6.2 million metric tons, indicating that many mines continued to operate even though they were unable to cover all production costs. For U.S. producing mines, the estimated average cost of production per pound (including profit at a 15-pct rate of return) was $0.15 higher than the average cost in other market economy countries.

Jan 1, 1983

By J. L. Johnson

The U.S. Bureau of Mines investigated the recovery of tin and silver from the Coal Creek deposit in the Talkeetna Mountains, AK. Approximately 5 million st of reserves grading 0.2 pct Sn with silver credits of 0.2 tr oz/st have been delineated by drilling. A 10-to 25-pct Sn gravity concentrate was produced by treating the minus 20-mesh ore with a spiral, then regrinding to minus 65 mesh and tabling. Sulfide contamination in the gravity concentrate was as high as 60 pet. Sulfide flotation of this concentrate produced tailings containing 40 to 50 pet Sn. Overall recovery was 76 pct for tin but only 5 to 10 pct for silver because of losses during sulfide flotation. Other methods tested to clean the concentrate included cassiterite flotation, gangue flotation, nitric acid leaching, and wet and dry magnetic separation. Tin beneficiation tests on the minus 325-mesh fraction included cassiterite flotation, vanning, sulfide flotation, and fuming. The bench-scale and locked-cycle tests were used to estimate the mass flows for a 1,000-st/d plant.

Jan 1, 2010

By M. Howard Berliner

The Harding pegmatite dike is well known for the production of spodumene and lepidolite in the period 1920 to 1930. It attained greater prominence during the last war by being the largest producer of domestic tantalum ore from the rare mineral microlite. The deposit is believed to be the only proved reserve of tantalum ore in the United States today. In 1943 the main portion of a large tantalum-bearing zone in the Harding dike was developed by the Bureau of Mines with the assistance of the Federal Geological Survey. Analysis of this zone from 39 diamond drill holes and quarry exposures showed a large deposit containing 2 pounds of microlite per ton and 21 percent spodumene, In September 1948, the Bureau of Mines resumed development of the deposit with a view to extending the tantalum-bearing zone farther to the southwest or delimiting the ore body. Seven diamond-drill holes failed to penetrate the ore zone in its southwestward projection, Much of the following general information is summarized from the report on the first exploratory work of the Bureau of Mines by John H. Soule.2/

Jan 1, 1949

By G. V. Sullivan, G. F. Workentine

Beneficiation studies were conducted by the Bureau of Mines on three samples of low- grade chromite - bearing material from the Stillwater complex of Montana . The objective of the study was to develop methods for recovering chromite from low- grade materials to improve the domestic reserve situation . Samples were obtained from the three largest deposits in the district , Mouat , Benbow , and Gish . The chromic oxide ( Cr₂ 0 ) content of the ore and of the chromite was about the same in each of the samples . The major gangue constituents ranged from clean olivine in the Mouat sample to such altered minerals as serpentine and talc in the Benbow and Gish samples . Tabling , flotation , high- tension electrostatic separation , and combinations of processes were applied to each ore . Treatment of the Mouat sample ( 9.95 percent Cr₂ 0 ) by high- tension electrostatic separation , a combination of tabling and high- tension electrostatic separation , and tabling with middling retreatment resulted in concentrates that graded 42.8 , 42.0 , and 40.7 percent Cr₂03 at chromium recoveries of 85 , 86 , and 84 percent , respectively . Other techniques were less selective . 2 The Benbow sample ( 7.75 percent Cr₂0 ) responded most selectively to tabling with middling retreatment and a combination of tabling and hightension electrostatic separation to produce concentrates of 40.1 and 39.5 percent Cr₂g with each process having a chromium 2 recovery of 69 percent . Response of the Gish sample ( 8.04 percent Cr₂03 ) to the various concentration techniques was about the same as that of the Benbow sample , but in general , somewhat less selective . A combination of tabling and high- tension electrostatic separation resulted in a concentrate that contained 71 percent The Mouat mine was reopened in 1953 when the American Chrome Co. contracted with the Federal Government to produce 900,000 tons of chromite concentrate . The ore , averaging 20.2 percent Cr₂03 , was treated by tabling to produce a 38.5 - percent Cr₂ O concentrate.

Jan 1, 1964

By N. S. Dalal, Xianglin Shi

"The mechanism of vanadium(V) V ) toxicity is still not fully understood in spite of extensive current effort (1-3). The presence of a vanadium(V) V ) -dependent NAD ( P )H oxidase in cell membranes suggests that at least one of the pathways involves oxidation of NAD(P)H (1-3). Considerable effort has therefore been devoted to finding the mechanism of NAD ( P ) H-oxidation by va¬nadium( V ) (1-19). Recently Liochev and Fridovich (4, 16) provided a critical review of vanadium( V) -stimulated NAD (P )H oxidation by plasma membranes. They out¬lined a mechanism in which vanadium(V) V )-stimulated oxidation of NAD ( P )H by biomembranes involves an O2 - initiated free radical chain reaction (4 ). While the above may be the major pathway for the vanadium-me¬diated NAD (P )H oxidation in membrane-related sys¬tems, some recent results suggest that in the presence of NADPH the flavoenzyme glutathione reductase can function as a vanadium(V) V ) reductase (18). Because of the significance of this result in relationship to the mech¬anism of vanadium( V) metabolism and the novelty of the metal-reductase behavior of a flavoenzyme, we have car¬ried out additional studies on one-electron reduction of vanadium( V) by two other, related flavoenzymes: lipoyl dehydrogenase and ferredoxin-NADPH oxidoreductase. These two enzymes were selected because they are known to catalyze a one-electron reduction of Cr ( VI ) (19-21 ), which is isoelectronic with vanadium( V ).The present study also reports on the generation of hydroxyl ( • OH) radicals in the vanadium( V) -flavoen-zyme redox system without exogenous H2O2. The • OH study was undertaken because • OH radicals are known to be generated in reactions of vanadium( IV) with H2O2 (17,18,22-27). For example, Piette and co-workers (17, 22) have studied effects of vanadium(IV) IV ) on lipid per-oxidation and NADPH oxidation and suggested that va-nadium( IV) -induced • OH radical formation may play an important role in vanadium( V) toxicity. Carmichael (25, 26) investigated the reaction between a RNA /VO 2' complex and H2O2 with a view to probe the possible re-lationship between vanadium( IV) -mediated • OH radical generation and DNA damage. He has suggested that in this reaction the • OH radical adds to the C (5) carbon of uracil, causing nucleotide damage, similar to what occurs in the nucleotide /Fe2+ / H2O2 reaction (28) and in y-irradiated aqueous solutions of nucleic acids (29 ). To our knowledge, however, there is as yet no report on ·OH radical generation in any reaction involving the reduction of vanadium ( V) by a well-characterized enzyme, without exogenous H20 2 • The present study provides evidence that ·OH radicals can form in a flavoenzyme-mediated reduction of vanadium( V) to vanadium( IV) and that this process involves also the reduction of molecular oxygen ( 0 2 ) to H20 2 • The H20 2 thus generated reacts with vanadium( IV) to produce ·OH radical, in analogy with the Fenton reaction ( Fe2 + + H20 2 - Fe3 + + OH- + ·OH)."

Mar 1, 1992

By Ronald T. Mayerle

In 1989, the U.S. Bureau of Mines conducted a mineral investigation of the Mallard study area near Elk City, Idaho. The study area comprises most of the original Mallard RARE II area (1-847) plus some additional lands. The investigation is part of an ongoing, multi-year study of north-central Idaho that is being conducted in cooperation with the Idaho Geological Survey and the U.S. Geological Survey (USGS). The only identified resources are rock suitable for road metal. Five lode prospects and a pyrite-bearing rock quarry, which is operated by the Forest Service for aggregate, were examined for metals. One of the prospects warrants additional exploration for silver in quartz veins, but the chance of finding an economically minable deposit is limited. Several rock and stream sediment samples were anomalous in various metals. Two of the more promising localities for gold and/or other metals are adjacent to a unit of the Frank Church-River of No Return Wilderness that the USGS classified as having a moderate potential for gold deposits related to fossil hot springs.

Jan 1, 1991

By G. E. McElroy

This report discusses the construction and use of an all-pressure psy- chrometric chart in which the requirements of simplicity of appearance and absolute accuracy have been waived, to a certain extent, to provide for the rapid determination of psychrometric data and for the rapid solution of air- conditioning problems of major interest to the mining industry. Many mines in which air-conditioning problems are important are situated at elevations far above sea level and embrace great differences in elevation - in excess of 8,000 feet in certain mines → throughout their airflow circuits. Under these conditions, the effects of variations in the pressure of the at- mosphere upon the physical properties of the mixture of air and water vapor of which it is composed are considerable and should be taken into account in the solution of problems. The simple types of psychrometric charts in common use, such as the Carrier, Bulkeley, Hill, and Goff (American Society of Heat- ing and Ventilating Engineers Guide), are not generally suitable, in that they are drawn for a single barometric pressure 29,92 inches mercury.

Dec 1, 1947