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By Bob Thomas, Syd Peng, Quanzhong Gu, Gene Wilson, Gerald L. Finfinger

Identifying the properties of overlying rocks in underground mining operations is important to ensure the appropriate roof support design is used to maintain stability of the mine entries. Recently J. H. Fletcher & Co. developed a monitoring and control system for roof bolters for the underground mining industry. The system records the drilling parameters used during roof bolt drilling and the information can provide insight into the physical properties of the roof strata. The parameters include thrust, rotational speed, torque and velocity and the measurements are collected every 0.1 second during the operation. The drilling parameters were analyzed to determine the application of identifying the strength of rocks being drilled from the measurements. The data was converted into the specific energy of drilling which is a measure of the amount of energy required for removing a given unit of rock during a drilling operation. The laboratory studies completed to date indicate a fairly high correlation between the specific energy of drilling and the unconfined compressive strength of :he rocks that were drilled. Additionally, the drilling parameters were shown to be effective for identifying the presence of fractures or bed separations between rock layers. The thrust, torque and specific energy of drilling were all good indicators for identifying the fractures or separations. Regardless of the drilling parameters used during the drilling experiments, the location of the fractures were identified. In order to determine the application of the drilling parameters for identifying roof rock properties, two series of experiments were conducted. The first series of experiments used three "manufactured" roof layers that had various rock samples embedded in concrete blocks. The rock samples included three types of sandstone, marble, and argillite. Another concrete block was poured with foam inserts to simulate large bedding separations (2 to 8-in). Two other manufactured blocks were constructed using high-strength concrete with cardboard layers embedded to simulate smaller fractures or bedding separations. The size of the cardboard layers varied from 1/8- to 1-in thick. One of the blocks had the cardboard layers embedded at an inclined angle to determine the effect of the orientation on the drilling parameters. A series of experiments was conducted with the rotational speed and the penetration rate held constant and the thrust and torque allowed to vary. The information collected from the experiments is used to determine the application of the drilling parameter measurements for identifying rock properties, fractures and bedding separations.

By C. M. Frost

Crude shale oil prepared by gas-combustion retorting of Colorado oil shale was hydrogenated over a cobalt molybdate catalyst at an operating pressure of 1,000 psig, temperatures of 781° and 761° F, and liquid hourly space velocities of 0.10 and 0.05 Vo/Vo/hr, respectively. The yields of total liquid products and the amounts of nitrogen and sulfur removed were comparable with those obtained at an operating pressure of 3,000 psig and a liquid hourly space velocity of 1.0 Vo/Vo/hr. Approximately 1.5 times as much gasoline was produced at the lower pressure and space velocities.

Jan 1, 1973

1. In 2001, a total of 785 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Examples of nonmetal mining operations include the mining of clay, trona, barite, phosphate rock, gypsum, talc, gemstones, and pumice. Nonmetal mines comprised 5.4% of all mining operations.1 • Nonmetal mining operations are located in all but seven states or territories (Alaska, Delaware, Maine, New Hampshire, Rhode Island, Puerto Rico, and the Virgin Islands). • The median number of operator employees per nonmetal mine was 6.1.2 • Mines producing common clay comprised 31.2% (n = 245) of all nonmetal mining operations.

Jul 1, 2003

By K. O. Bennington

Enthalpies of formation of three sodium titanates were determined by hydrofluoric acid solution calorimetry, The values obtained for formation from the elements at 298.15° K are -370.9±0.5 kcal/mole for Na2TiO3, -832.1±0.9 kcal/mole for Na2Ti307, and -1,510.9±1.7 kcal/mole for Na2Ti6013. Tables of enthalpies of formation and Gibbs energies of formation are given as a function of temperature both from the elements and from the component oxides for Na2Ti03 and Na2Ti307.

Jan 1, 1973

Provide the U.S. mining industry with a user friendly computer program to calculate stresses in underground coal mines in order to improve safety conditions for mine workers. Capabilities of MULSIM/NL MULSIM/NL (multiple seams, nonlinear) is a three-dimensional boundary-element method (BEM) program developed at the U.S. Bureau of Mines for stress and displacement analysis of coal mines. It can analyze one or two parallel seams that can have any orientation with respect to the Earth's surface. Three main new features distinguish MULSIM/NL from its predecessors: (1) non¬linear material models, (2) multiple mining steps, and (3) energy release and strain energy computations. MULSIM/NL has six material models for the in-seam material: (1) linear elastic for coal, (2) strain softening, (3) elastic plastic, (4) bilinear hardening, (5) strain hardening, and (6) linear elastic for gob. The multiple mining step capability enables the user to efficiently simulate a changing mine geometry. Finally, MULSIM/ NL computes energy release rate due to mining using the most recent concepts advanced by Salamon.

Jan 1, 1993

By Dale E. Wittmer

Nonoxide ceramic materials could substitute for high-temperature alloy steels containing imported critical and strategic materials such as cobalt, chromium, and nickel if their high-temperature properties can be improved. An important result of this substitution would be a reduction of the Nation&apos;s need for imports of critical and strategic materials. In this Bureau of Mines investigation, the primary objective was to produce high-purity u1trafine (particles <5 ~m equivalent spherical diameter (ESD)) alpha-silicon carbide (a-SiC) powders with improved high-temperature properties using the Bureau&apos;s patented turbo-milling process. A secondary objective was to determine the feasibility of using polymer mill construction materials as a means of eliminating metal contamination from the turbomill. U1trafine a-SiC powders with BET (Brunauer-Emmett-Te11er) surface areas from 30 to 35 m2/g (~0.06 ~m particle ESD) were produced in an all-polymer turbomi11. These high-purity powders (with I-pct Band I-pct C additions) hot-pressed to greater than 99 pct of their optimal density and exhibited properties commensurate with those of commercially available a-SiC. The most promising of the construction materials tested for the major wear surfaces of the turbomi11 was u1trahigh-mo1ecu1ar-weight (UHMW) polyethylene, a polymer thermoplastic.

Jan 1, 1984

By T. O. Llewellyn

The Bureau of Mines, as part of its goal to develop technology that can conserve domestic mineral resources investigated beneficiation methods for recovering phosphate minerals from two Southern Florida deposits with high magnesium content. Chemical analyses of sized fractions indicated that no coarse pebble concentrate could be produced from either deposit. Conventional fatty acid-fuel oil batch flotation tests on two phosphate samples, analyzing 6.8 and 8.5 pct P205, yielded concentrates containing 28.97 to 29.80 pct P20S at recoveries ranging from 72.4 to 76.9 pct of the flotation feed. The MgO content ranged from 1.20 to 1.36 pct. Bubbling S02 gas through an aqueous concentrate slurry, further reduced the MgO content of these phosphate concentrates to 0.5 and 0.8 pct, but with a concomitant loss in the phosphate recovery. Settling characteristics of slimes from both phosphate samples showed a slow settling rate, which is a typical characteristic of other slimes in the region.

Jan 1, 1981

By A. T. Iannacchione

Underground stone mining represents an emerging sector for the U.S. mining industry. As this expansion takes mines under deeper cover and as more efficient mining methods are utilized, adequate stone pillar design methods will become more important. It is the purpose of this paper to examine current design practices and to discuss issues for safe mine layouts so that a rational first approach towards balancing the demands for increased production can be weighed against increased risk to worker safety from rib instabilities and pillar failures. Seventy-two stone mine pillar designs were examined. Pillars with width-to- height ratios below 1.5 and subjected to excessive stress levels appear more likely to fail. When width-to- height ratios fall below 1 .O, defects in the pillars, such as through-going discontinuities, can have a significant influence on stability. Discontinuity persistence, dip, material properties, and orientation are important factors controlling pillar strength. The influence of discontinuity dip, a characteristic easily identified in the field, was examined so that its presence could be accounted for in developing generalized guidelines for pillar design.

By E. F. Ferrell

The Bureau of Mines, U.S. Department of the Interior, studied the use of manganese sea nodules for catalytic oxidation in air of 1 pct carbon monoxide, 1 pct propane, and 1 pct methane. Catalysts were prepared from both Pacific Ocean and Atlantic Ocean nodules and compared with a platinum catalyst using a fixed-bed, steady-state microreactor with gas chromatographic analysis. Combustion temperatures with manganese nodules were 50° to 100° C lower than those with the platinum catalyst. Ion-exchange addition of rare-earth promotors to the nodule catalyst decreased combustion temperatures an additional 5° to 45° C.

Jan 1, 1978

By Ernest R. Rodriguez, Allen D. Look

"INTRODUCTION The underground mine of the Miami Copper Co. has operated since 1927 without a fatality from blasting or the handling of explosives. To improve safety and efficiency, electrical blasting has been used exclusively since 1934. During the period January 1, 1934, to December 31, 1948, inclusive, over 4,000 tons of explosives were used to produce 60,925,071 tons of ore with 896,760 feet of development footage and 2,591,788 square feet of undercut area.The purpose of this paper is to recount the company's precautions to insure safe handling of explosives at this operation, where safety involves careful planning rather than ""trial and error.""GENERAL INFORMATIONThe Miami Copper Co. operates on underground mine in a large, low-grade, Porphyry copper deposit near Miami, Ariz. The deposit contains numerous fractures and planes of weakness, which contribute to ease of working the ore bodies by the block-caving method of mining.An individual stope-caving method is used with stoles 150 feet by 200 to 300 feet and 30- to 50-foot pillars between stapes. After the stope is undercut, the ore is drawn through the draw raises on the grizzly level, and thence through the transfer raises to the ore chutes on the haulage level.Access to the mine is by four active shafts, three of which are primarily for ventilation. No. 5 shaft is used for both hoisting and service. There are four operating levels in the mine. The elevations of the grizzly levels are governed by the contour of the bottom of the ore body and therefore vary in different locations in, the mine.Grizzly levels are on the 850, 900, and 975 levels. The 1,000 level is the haulage level. This mine operates in very low-grade ore and requires economical handling of large tonnages safely and efficiently."

May 1, 1950

By Fred Garcia, William P. Diamond

As part of its mine safety and health research program, the National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, has been investigating the geologic and mining factors influencing methane gas emissions associated with longwall mining. A primary focus of this research has been the consequences of increasing longwall panel dimensions, particularly face width, in gassy coalbeds. Continuous longwall face emission monitoring studies were conducted at two adjacent mines operating in the Pocahontas No. 3 Coalbed, where longwall faces were to be extended from 229 to 305 m (750 to 1,000 ft). Average longwall pass methane emission rates for 229-m (750-ft) wide faces were 61 % (0.072 m31sec (153 cfm)) higher at the VP-3 Mine than at the VP-1 Mine. It was predicted by regression analysis of methane emissions data from 229-m (750-ft) wide faces that extending faces to 305 m (1,000 ft) would increase methane emission rates by only 7%, or 0.009 m3/sec (20 cfm), to 0.144 mysec (304 cfm) at the VP-1 Mine. In contrast, it was predicted that extending faces to 305 m (1,000 ft) at the VP-3 Mine would increase methane emissions by as much as 13%, or 0.029 mysec (65 cfm), to 0.268 dlsec (567 cfm).

Jan 10, 1999

By James H. Russell

Several solid sorbents were compared for their effectiveness in removing sulfur dioxide from flue gases. The materials were tested for the rate of sorption and capacity at about 300° C, and rate of regeneration around 700° C in thin beds and in 4-inch-diameter fluidized beds. Rates of material loss were also estimated. The sorbents tested included three samples of alkalized alumina, two samples of sodium carbonate-impregnated alumina, and one proprietary sample of porous silica impregnated with copper and iron compounds. The results showed that all the alkalized aluminas had good sorption capacities and rates, required high temperature regeneration, and suffered excessive material loss; the sodium carbonate-impregnated aluminas (1) had high sorption rates but barely adequate capacities, (2) required high temperature regeneration, and (3) suffered excessive material losses; and the copper-iron impregnated silica suffered only slight material loss and could be regenerated at a relatively low temperature, but the sorption rate and capacity were too small. None of the sorbents met all the arbitrary performance criteria that follow: sorption rate constant of 1 min-1, sorption capacity of 0.1 g sulfur per g sorbent, regeneration rate constant of about 0.075 min-1 at a reasonable temperature, less than 0.07 pct per hour material loss during operation, and a chemical life of 500 cycles.

Jan 1, 1971

By Donald P. Tuchman, Robert P. Vinson, Steven J. Page

Researchers at the National Institute for Occupational Safety and Health (NIOSH) have long used stationary tapered element oscillating microbalances (TEOMs®) in laboratory settings. They have served to assess the mass concentration of laboratory-generated particulates in experimental , dust chambers and they provide a reference method for comparison with other particulate- measuring instruments. Current NIOSH research is focused on further adapting TEOM technology as a wearable personal dust monitor (PDM) for coal mining occupations. This investigation&apos;s goal is to help identify, quantify, and provide means for resolving certain TEOM- related error. The present research investigated bias caused by thermal effects on filter assemblies. New filters used in the PDM for 8 h tests show an average positive bias of 25.5 pg, while similar tests of equivalent filters used in two 1400A model TEOMs show an average positive bias of 34.3 µg. The derived bias values allow correction of previously collected biased data. Also, pre- heating the filters for 24 h at 46° C shows significant bias reduction, with PDM pre-heated filters subsequently averaging -3.3 µg and 1400A TEOM filters averaging 5.9 µg. On a single-point comparison to gravimetric sampling, a 25.5 µg bias is only significant at low mass loadings. At 2.5 mg, this bias represents a negligible 1 % of the mass measurement. If ordinary linear regression is used, the bias is still insignificant. However, if the more valid weighted linear regression is used, it gives more weight to the smaller dependent variable values, which are more impacted by the bias. Consequently, what is 1% bias on a single high-mass value can translate into a larger bias percentage at high-mass values when performing a weighted regression on data that include a large number of low-mass values.

By Charles E. Munroe

On March 14, 1921, an explosion occurred at about 6:15 A.~. on the premises of an iron-mining concern throug:1 which two magazines, one containing upwards of 9,000 pounds ot a high explosive of the dynamite class, and a second, 60 feet distant, containing upwards of 10,000 No. 6 detonators, were completely destroyed, and a ncratertt,? f3et deep by 30 feet in diameter, was excavated in the gro~ at ~he place whare the mag~iine containing the high explosive had been lo~ated. As a rule any eye wit~esses to the circumstances im.~ediataly preceding and d(irectly concurrent with a.c.ci.:lental ex;losions ar.e victims of s11ch explosions, and, therefore, the conclusions reached as to the cauoa. of such explosions must, perf'orce, be based aln:ost completely on circumstantial evidetJ.ce. In this iii.stance, b:ecause both the explosive and detonators were of -orov{:;d: character; because of the time of the day and the state of operations iit the·· time of the e:.q,losion; because the rerroteness of the location of the n:-1agazi::1es 1 0::1 the side of a ravine, easily admittfi of unobserved approach; beca:iise differencas existed, and because no obvious cause was at once apparent, there arose suspicfon that the explosion was not accidental.

Sep 1, 1921

By Joseph E. Matta

The Bureau of Mines conducted tests using a tracer-gas technique to measure the effectiveness of the jet fan, which is often employed in mines to ventilate dead headings. Results of these tests show that jet fans can (1) ventilate dead headings beyond the maximum penetration distance indicated by smoke-tube detection of air movement, and (2) redistribute available fresh air through larger working areas. However, if the fresh air base is insufficient, the fan will merely recirculate the contaminated air and disperse it over a larger volume.

Jan 1, 1978

By Robert L. Marovelli

The thermal conductivities of six rocks were measured by the transient line source method over the temperature range of -850 to 1,500° F. Close-fitting ceramic probes were used in 0.065-inch-diameter holes drilled through 5-to 6-inch-thick rock specimens. Taconite, granite, quartzite, and basalt were used in the tests. The method yields absolute data and is applicable to both laboratory and in situ measurements.

Jan 1, 1965

By E. J. Kloos

The Bureau of Mines developed a test for evaluating gas masks designed to protect against phosphine gas; phosphonium iodide is used as a source of phosphine. Gas masks approved by the Bureau for respiratory protection against phosphine include the GMC-SS-1, Mine Safety Appliances Co.; the LG-10 and LG-10G, Willson Products Division, The Electric Storage Battery Co.; and the 084-PHOV-R, Acme Protection Equipment Co.

Jan 1, 1966

By E. J. Kloos

The Bureau of Mines developed a test for evaluating gas masks designed to protect against phosphine gas; phosphonium iodide is used as a source of phosphine. Gas masks approved by the Bureau for respiratory protection against phosphine include the GMC-SS-1, Mine Safety Appliances Co.; the LG-10 and LG-10G, Willson Products Division, The Electric Storage Battery Co.; and the 084-PHOV-R, Acme Protection Equipment Co.

Jan 1, 1966

By E. C. Lane

This report on properties of commercial motor fuels is the twelfth in a series made in accordance with a cooperative agreement between the Cooperative Fuel Research (C.F.R.) Committee and the Bureau of Mines of the United States Department of the Interior. The first report contained data on motor gasolines sold during the winter of 1935-36.V The -present report, covering the summer of 1941, presents analytical data for 1,857 samples, representing the products of approximately 135 companies. As in previous surveys, these companies include both large and small suppliers. In addition, the Pacific coast is represented by data averaged by the Pacific Coast Technical Group before being submitted, and these data are published exactly as they were received. Conforming to previous surveys, the data cover three groups of samples -- regular-price, premium-price, and third-grade gasolines -- and each group has been aver aged separately. The number of samples, items, and brands comprising each group, exclusive of those of the Pacific coast, are as follows: Regular price, 1,010 samples, 291 items, and 86 brands; premium price, 577 samples, 263 items, and 78 brands; third-grade gasoline, 270 samples 159 items, and 74 brands. The meanings of these terms as used in the surveys are as follows: Sample: The individual supply of gasoline obtained at the filling station and analyzed in the laboratory.

Jan 1, 1942

By J. M. Oestreich

Supercritical water (sew) Is being tested for commercial use 1n several organic extraction systems but little work has been done on the extraction of metals from minerals. This lack of information prompted Bureau of Hines (BOM) research into the sew treatment of minerals. As a result, this research project is intended to serve mainly as a starting point for further experimentation. A simple flow-through reactor was built out of high pressure tubing and used to treat minerals with SCU at 400? C and 3500 to 7000 psi. The research produced four main conclusions: (1) carbonates of copper, iron, and lead convert to oxides; (2) most iron minerals showed alteration to oxides with some iron dissolution; (3) valuable trace elements including nickel, chromium, and others leached to some extent from sea minerals along with some calcium, iron, silicon, and sulfur; and (4) treatment of sulfides extracted elemental sulfur and resulted in several alteration reactions, though with the exception of cinnabar and the iron bearing minerals, the metals in sulfides were mainly insoluble. Surface alterations on many of the minerals show significant changes have occurred in the minerals even when only minor extractions were detected. These surface effects may be very important when used in conjunction with flotation processes since the sew treatment may selectively enhance or suppress a mineral&apos;s floatability.

Jan 1, 1989