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By R. H. Grau, A. Sainato, S. J. Schatzel, T. M. Kohler, A. T. Iannacchione

This Bureau of Mines research study found gas emission rates from an advancing face, and flows and pressure of gas from an exploration drill hole were dependent upon the geology of salt encountered in a domal salt mine. Normal production-grade "pure" salt adjacent to an anomalous' zone was found to have a methane emission rate of less than 5 ft3/ ton (0.1 m3/t) of mined salt from a room advanced by a continuous miner. Extremely low gas flows [less the 4 ft3/h (0.1 m3/h)] and lack of pressure buildup were also observed from this normal salt in a 154-ft (47-m) exploration drill hole. These data indicate that methane emissions should not be a problem when mining in this type of salt. In the adjacent anomalous zone, methane emission rates ranged from 15 to 70 ft3/ton (0.4 to 1.8 m3/t) of mined salt from an advancing face. Gas flows of approximately 42 ft3/h (1.2 m3/h), and pressures in excess of 900 psig (6,200 kPa) were observed in an exploration drill hole when the anomalous zone was encountered. This information suggests a greater methane emission hazard from the anomalous zone than from the associated normal salt. If this trend of increasing emissions problems associated with anomalous zones of salt is common with similar anomalous zones encountered or observed in other domal salt mines, then special control strategies should be employed to minimize this potential mining hazard.

Jan 1, 1984

By R. V. Ramani, R. Srikanth, R. Zhao

"A two-pan study was conducted to understand the factors affecting respirable dust generation potential or dustiness of coal seams. In the first part, the data from three prior comprehensive laboratory studies was analyzed to establish quantitative relationships between respirable dust generation potential and coal characteristics. This analysis indicates that respirable dust generation rate is positively correlated with Hardgrove Grindability Index (HGI), fuel ratio (fixed carbon/volatile matter), Vitrinite Reflectance (VR), and Level of Organic Metamorphism (LOM). In the second part, specially-designed single breakage experiments were conducted to determine the primary dust generation potential of 17 coal samples obtained from four continuous miner sections, three longwall sections, and the Penn State Coal Data Bank. The single breakage study indicates that primary dust generation rate is positively correlated with fixed carbon content, fuel ratio (fixed carbon/volatile matter), VR, and LOM. Since VR and LOM are strongly influenced by the process of coalification, differences in respirable dust generation rates in different coal seams may be explained by the thermal metamorphism of sedimentary organic matter during subsurface burial.Mineral particles in the range of one to five microns, if inhaled in sufficient amounts, lead to a number of lung diseases generally referred to as pneumoconiosis. A priori knowledge of the mechanisms and rates of fine particle generation during mining can aid in the development of more effective technology for controlling primary dust generation. Unfortunately, the data and knowledge currently available are not adequate for this purpose. In fact, a committee of the National Academy of Sciences on the measurement and control of dust concluded that the knowledge of the fundamental mechanisms by which coal mine dust is generated and a part of it is entrained in the mine atmosphere as respirable dust is not sufficient to clarify, let alone control, the processes involved (Anon., 1980). Under a research contract from the U.S. Bureau of Mines, Stecklein et al. (1982) have identified a number of fundamental research issues for understanding the coal fragmentation and entrainment processes.Reduction of dust generation is the best means of control since fine particles are difficult to control once they become airborne. Therefore, considerable research efforts have been directed to understand the factors influencing dust generation and entrainment, including machine design, water sprays, and ventilation. Laboratory studies have been conducted on the mechanical action of bits and machine power requirements (Evans and Pomeroy, 1966; Roepke, 1984). Since the physical characteristics of coal play an important role in the process of breakage, a number of laboratory studies have been conducted to study the relationship between coal characteristics and respirable dust generation (Baafi, 1977; Moore, 1986; Polat, 1990; Thakur, 1971). Several studies have been conducted on the relationships between coal characteristics and airborne dust concentrations (Hamilton and Knight, 1958; Khair and Xu, 1991; Organiscak and Page, 1993; Page et al., 1993). A limited number of studies have also been conducted on the relationships between coal characteristics and airborne dust concentrations in mines (Organiscak et al., 1990). Yet, no reliable method has been developed to rank coal seams according to their respirable dust generation potential. The conclusions derived from previous studies can be summarized as follows:"

Dec 1, 1996

By Carl N. Anderson

This paper, which is one of a group presented by the United States Bureau of Mines covering mining practice in different districts, deals in particular with the methods employed in mining the horizontal type of zinc-lead orebodies of the West Baxter area of the Tri-State zinc and lead district. These orebodies, locally termed "sheet-ground" bodies, with their relatively low working faces and low tenor of zinc and lead, require changes in the mining practice which is used in the balance of the district. In addition to the general mining methods, this paper also describes the system of hand sorting employed prior to the direct milling of the ore. The Hartley mine is situated mile west of Baxter Springs, Kans., as indicated in Figure 1. Its general outline and the location of the shafts with respect to the milling plant are shown in Figure 2.

Jan 1, 1932

By C. P. Fang, V. A. Marple, K. L. Rubow, P. H. McMurry

"It has been known for some time that sizes of aqueous particles may be affected by flow-induced relative humidity (RH) changes. The RH of air flowing through an impactor decreases as a result of pressure drop through the impactor and increases because of aerodynamic cooling within the high-speed jets, as illustrated in Figure 1. Because the sizes of aqueous particles depend on RH, the impaction stage on which such particles are collected may be different from the stage where they ought to be col¬lected, based on the particle size at the sampler inlet.Fuchs (1980) reviewed literature on water vapor condensation in impactors. The reviewed impactors operated at jet velocities of 100-250 m/s. Particle size increases ow¬ing to water vapor condensation were found in all cases. In one case (Khorguani et al., 1970), it was found that very small droplets (Dp <_ 0.02 um) containing sodium chloride and silver iodide were collected in an impactor with a cut point of 0.32 µm and a jet velocity of 100 m/s. Fuchs believed that such particles could not be captured in an impactor without having been enlarged by condensation. Winkler (1974) sampled at¬mospheric dust with a rectangular nozzle impactor that had a nozzle cross section of 0.3 x 15 mm, a cut size of 0.4 um, and an average jet velocity of 100 m/s. No adhesive was used on the impaction plate. The collection efficiency increased as air humidity was increased from 20% to 100%. The effect was especially noticeable in the increased collection efficiency for hygroscopic particles, and was attributed to condensation.Extensive theoretical and experimental research work on the distortion of the particle size distributions in impactors was done by Biswas and coworkers (1985, 1987). The impactors employed in the study were a low-pressure impactor with high jet velocity stages (Hering et al., 1978, 1979) and a conventional six-stage impactor, Sierra's model 226, operated in the incompressible regime. Ammonium sulfate aerosols were chosen for the study. In the low-pressure impactor, an orifice operating at a Mach number of 1 causes a sudden pressure drop, significantly reducing the RH in the next two stages (stages 5 and 6). This results in a 0.15-um diameter ammonium sulfate droplet shrinking to about 0.07 um at stage 5 when the inlet RH is 95%. In stage 7, the tempera¬ture drop is considerable because the jet speed is sonic. For an inlet RH of 95%, a 0.03 um droplet grows to about 0.06 um. However, the same size droplet at an inlet RH of 25% grows to only 0.04 um. For the Sierra model 226 cascade impactor that is operated with a Mach number of 0.27 at the last stage (stage VI), it was found that for an inlet RH of about 67%, particle growth would occur in stage VI. At 80% RH, both stages V and VI were affected. Biswas et al. (1987) stated that Mach number alone does not determine the size biasing; the type of aerosol, the inlet conditions, the temperature and pressure ratio, and the impactor geometry (throat length, jet-to-plate distance, etc.) must be considered for each stage in evaluating the distortion of the particle size distribution."

Mar 1, 1992

By A. J. Kraemer

[The Bureau of Minas for a number of years has been studying the properties of crude petroleum from producing fields in the United States and Western Hemisphere and has published a series of reports on these fields, including oil fields of Texas.5]

Jan 1, 1927

By R. A. Beall

This paper summarizes the development of a furnace for producing titanium castings. The general problem is outlined and chronological details are given on the construction and operation of four different casting furnaces, all utilizing consumable-electrode arc heating and water-cooled copper crucibles. Of the two methods of pouring, the tilt-pour technique has been more satisfactory than bottom tapping. Mold design, electrode fabrication, and deep-pool production are discussed. INTRODUCTION In the early summer of 1953 the Bureau of Mines was contacted by the Department of the Army through Watertown Arsenal to explore the possibility of conducting research on casting titanium metal. The objective of the program was "to develop a technique for producing formed castings of titanium metal not less than 40 pounds in weight and without introduction of deleterious contamination."

Jan 1, 1956

By J. C. Edwards

The Bureau of Mines developed a mathematical model for analysis of the impact of scrubber bed length, porosity, and gas flow rate on the absorption of C02 in a breathing apparatus. The model accounts for the decrease in available absorbent through chemical conversion. The pre-dicted efflux of C02 from a canister containing LiOR compared favorably with measured values reported elsewhere. It was determined from a com-putational study that the time for breakthrough of C02 at a prescribed level is nearly directly proportional to bed length and inversely pro-portional to gas flow and porosity.

Jan 1, 1987

By Michael G. Zabetakis

The autoignition temperatures (A.I.T.&apos;s) of natural and synthetic lubricants in air were generally found to decrease with increasing pressure. Of the two types of fluids, synthetic and natural, studied in some detail, the phosphate esters had higher A.I.T.&apos;s at any pressure between 1 and 200 atmospheres than the mineral oils. Most of the A.I.T. data obtained in this study obeyed the relationship predicted by Semenov&apos;s theory of ignition.

Jan 1, 1962

By Carl F. Wingquist

In support of Bureau of Mines studies of thermal fragmentation of rock, the elastic moduli of four types of rock were measured at temperatures ranging from room temperature up to 1,500° F (1,089° K). The sonic method was employed to determine the resonant frequencies of the rock specimens and from these frequencies, the elastic moduli were calculated. Data for Young&apos;s modulus, shear modulus, and Poisson&apos;s ratio are given as a function of temperature for Dresser basalt, Reserve taconite, Jasper quartzite, and Charcoal granite. Young&apos;s modulus and the shear modulus decreased with increasing temperature up to about 1,200° F and then became relatively insensitive to temperatures from 1,200° to 1,500° F.

Jan 1, 1969

By Thomas O. Llewellyn

This U.S. Bureau of Mines (US8M) report presents a concise review on sources, processes, supply, and historical use patterns of domestic cadmium. It also covers a preliminary estimated cadmium material balance for the year 1989.

Jan 1, 1992

By Robert H. Peters

This report presents a literature review conducted by the U.S. Bureau of Mines. The review summarizes what has been learned from recent empirical studies of the relationship between mine safety and characteristics of miners, mine management, and mining companies. The review is based on literature published in the United States during the period from 1976 to 1988. In addition to summarizing the empirical findings, this report discusses the implications and limitations of these studies, and gives recommendations for improving mine safety. An annotated bibliography section appears in the appendix.

Jan 1, 2009

By R. V. Rahfuse

Noncaking 0- by 2 -inch subbituminous coal from New Mexico was gasified with air and steam at 205 prig using a stirred-bed producer to determine coal losses by entrainment in the gas for this low-sulfur, high-ash coal which contained 20 percent particles smaller than 1/16-inch sieve size. The use of fine-sized coal has particular importance because most production from mechanized mines is smaller than 2-inch size. This initial attempt showed technical feasibility for gasifying New Mexico subbituminous coal containing small-sized particles in fixed-bed producers without excessive coal loss by entrainment. Dust loss averaged about 2 percent of moisture-free coal, most of which was recovered from the gas. Ash clinkering was controlled by adding 1,010 lb/hr steam to reduce tempera¬tures in the combustion zone. Yield of low-Btu fuel gas, 150 Btu per scf, dry, amounted to 69,800 scfh from 1,490 lb/hr coal (as received) and 3,450 lb/hr air (dry).

Jan 1, 1974

By T. SPOLAN, G. W. Jones, R. E. Kennedy

Information relative to the explosibility of acetylene at elevated pressures and means of handling acetylene safely under these conditions is of considerable interest at present. American practice limits the pressure at which acetylene may be generated and distributed to poiIits of' use. The pressure in portable acetylene generators is 15 pounds per square inch gage. Tests made by the Bureau of Mines have shown that 15 pounds per square inch gage is too high to prevent explosiofiS of gaseous acetylene in the absence of air; in fact, dry acetylene gai can be exploded at pressures greater than 5.9 pounds per square inch gage. The Bureau has been interested in the explosibility of acetylene for many years because of its continued: use for illumination in many metal mines and its general use in cutting 1illd~--eldifigoperations in the mining maus-try.

Dec 1, 1948

By R. V. Higgins

A numerical method is presented to calculate the isopressure (isobar) lines and streamlines for an oilfield from the pressure distribution. A knowledge of these lines is useful in the study of the flow of fluids in underground reservoirs, especially for those containing gaseous and/or liquid hydrocarbons. This work was done primarily to enable determination of the shape factors needed in the calculation of petroleum reservoir performance. However, it has application for the flow of water in aquifers, or electricity or heat in odd-shaped geometry. Techniques previously developed were used to calculate the pressure distribution. From this pressure distribution, the isopressure lines were calculated accurately by the method presented in this paper. Then by successively projecting orthogonal lines from one isopressure line to another, the streamlines are determined. From the coordinates of the isopressures and the streamlines, the shape factors can then be determined by a published method. Computer methods are presented to calculate the streamlines and isopressures for any well-spacing pattern existing within a field with multiple wells. The method reproduces the flow net for several well configurations having extensive geometrical variations. Such information provides the petroleum engineer with data from which he can compute oil recoveries for different patterns and thereby maximize the recovery of hydrocarbons from the reservoir.

Jan 1, 1972

By R. E. Peterson

Scrap iron is partially oxidized at elevated temperatures in the selective oxidation process to produce iron oxide and a dense residual metal of high purity. Investigation of the process was confined to converting automobile hulks into useful products. In one test series, compressed, sheared automobile scrap was processed at 1,000° C in a 36-foot-long rotary kiln at feed rates ranging from 300 to 1,200 lb/hr. Less fuel was required to maintain the temperature at the higher feed rates because of the heat generated from the burning of the combustibles and the oxidation of the iron. The bulk density of the residual metal exceeded 75 pounds per cubic foot. In an attempt to lower the quantity of contaminants in the residual metal, another test was designed using automobile hulks which had been prepared by ripping, a low-cost method of scrap fragmentation. Before oxidizing the ripped scrap approximately 62 percent of the total copper was removed in a tumbling, screening, magnetic separation and hand-sorting system. Cast iron made from the residual metal obtained by selective oxidation contained 0.15 percent copper; iron oxide scale obtained from the kiln averaged 0.13 percent copper. Pellets made from the scale demonstrated compressive strengths necessary for blast furnace reduction; lead and zinc were removed by volatilization when the induration was performed in a reducing atmosphere.

Jan 1, 1972

By V. J. Lynch, A. L. Peyton

"INTRODUCTION AND SUMMARYThe Brewer mine, near Jefferson, Chesterfield County, S.C., was originally operated as a gold mines as late as 1890 this mine was reported to have been one of the large gold producers in the southeast,Occurrence of topaz on the Brewer property was not reported until 1935, when it was discovered by Pardee and Parks. 3/ of the Federal Geological Survey while they were investigating gold deposits in the Piedmont province.During the 1940's the Chemical Engineering Branch of the Tennessee Valley Authority and the Electrotecbnical Laboratory of the Bureau of Mines at Norris, Tenn., investigated topaz from the Brewer mine to determine the possibilities of its use as mullite and for the production of calcium fluoride.From July 1950 through. April 1951 the Bureau of Mines conducted a diamond-drilling project at the Brewer mine to determine the grade and extent of the topaz deposits. Ten diamond-drill holes, totaling 2,344 feet, were completed, and 231 analyses of core samples were made during the course of the project.This report presents factual data relating only to the diamond-drilling project, The placer deposits on the Brewer property were previously investigated by the Federal Geological Survey 4/."

Aug 1, 1953

By Frank J. Wiebelt

The Carbonate King zinc mine is on the west slope of Kokoweef Peak, Ivanpah Mountains, San Bernardino County, Calif. It has produced more-than 10,000 tons of ore with a 39-percent?zinc content since mining operations began in 1940. The ore, consisting principally of calamine and smithsonite, occurs in replacements of the YellowPine limestone. Milling, has been done from the surface to a depth of 275 feet. Eight holes, aggregating 2,121, feet were drilled by the Bureau of Mines in an endeavor to establish extensions of the worked-out ore bodies and to develop new ones. Although indication of mineralization was found in several of the holes, no new ore bodies were developed.

Jan 1, 1949

By R. J. Matetic

The Bureau of Mines, as part of a program to improve mine planning and development, is currently investigating the effects of pillar load transfer, which can impact mining operations within a multiple-seam configuration. A comparative study was performed at two separate mine sites. The objective of this study was to compare two mines, each affected by this pillar load transfer mechanism, and to show how this interaction affected underground workings by the installing and monitoring underground instrumentation. At mine site A where the overburden was 1,000 ft, the innerburden thickness was less than a pillar width (40 to 45 ft), overlays of the mine layout show pillars were not superpositioned, excessive roof to floor convergence was measured, and pressure readings indicated pillar core loading only. At mine site B, the overburden was approximately 555 ft, the innerburden thickness was approximately 105 ft, overlays of the mine layout show pillars were superpositioned, minimal roof to floor convergence was measured, and pressure readings indicated a skin loading only.

Jan 1, 1988

By Charles A. Seitz

This Bureau of Mines report describes a chromatographic method for analyzing impurities in helium that utilizes a helium carrier gas contain-ing 25 to 30 ppm Ne. An example of the effect of trace amounts of nitrogen, methane, and moisture on the detector&apos;s response is shown. The added neon in the carrier does away with irregularities of the analysis which were experienced when the carrier contained up to 3 ppm Ne. The addition of 25 to 30 ppm Ne causes a loss of sensitivity, but the re-maining sensitivity is adequate for routine analyses. The high-neon carrier allows positive and more linear responses for eight impurities: neon, hydrogen, argon, oxygen, nitrogen, methane, carbon dioxide, and ethane. Neon concentration levels of 0.02 to 125 ppm in helium carrier gases were studied. The high-neon carrier has been in successful rou-tine use in Bureau of Mines helium facilities since October 1981.

Jan 1, 1985

By Lloyd Williams

1. The investigation shows that the bed identified as Wilder in this report is the only bed in Overton County that has produced commercial coal and is the only bed in which coal reserves were estimated for this report. Three other coal horizons were recognized but lacked enough data for reserve estimates. 2. Known measured and indicated reserves of coal, based on a minimum bed thickness of 14 inches and on 1,800 tons per acre-foot of coal in place, are estimated to be 19 million short tons, as of January 1, 1953. Of this total, 10 million tons represents coal 28 inches and more thick. Areas of the Wilder bed were omitted from the estimate because available data relative to the bed characteristics were too meager for making an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1955