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By M. R. Geer

The ever-increasing need to guard against stream pollution has intensified interest in the problems of handling and disposing of flotation tailing. Therefore, the Bureau of Mines investigated the possibility of using crushed washery refuse to adsorb the free water in thickened flotation tailings on a bench scale and then in a pilot plant because the conventional methods of disposing of coal flotation tailings--impounding them or filtering them so they are dry enough to be conveyed to the refuse dump--are sometimes either impractical because of space limitations or costly because of low filter capacity. Most of the refuse samples tested were of similar mineralogical composition and exhibited similar water retention capability. The amount of crushed refuse required to adsorb the water in a particular tailing was influenced greatly by the fineness of the solids in the tailing and hence the percentage of solids to which it could be thickened. The ratio of crushed refuse to tailing solids required to provide a mixture dry enough to be carried on an inclined conveyor belt varied from 2.4 to 6.4. Several chemical agents that were tested were very effective in turning the free water in tailings into a stable gel. Fly ash also was very effective in adsorbing water.

Jan 1, 1968

By N. S. Dalal, X. Shi

It has been known for more than a decade that vanadium (V) stimulates the oxidation of NADH by plasma membranes (1) but the underlying mechanism is still not fully understood. This effect has been attributed to a membrane-associated NADH-dependent vanadium (V) oxidoreductase (1). Subsequent studies suggest that vanadium ( V) can accept an electron from fiavoprotein dehydrogenase that oxidizes NADH (2). The phenomenon ofNAD(P)H oxidation coupled to vanadium(V) reduction has also been demonstrated in other biological systems (3-6). A recent electron spin resonance (ESR) study from our laboratory reported on the accumulation of vanadium (IV) duringthe reduction ofvanadate (vanadium(V)) by the ftavoenzymes glutathione reductase (GSSG-R),4 lipoyl dehydrogenase, and ferredoxin-NADP+ oxidoreductase in the presence of NAD(P)H (7). It was concluded therein (7) that these ftavoenzymes function as NAD(P)H-dependent vanadium(V) reductases. More recently, however, Liochev and Fridovich (8) have argued that the ESR data (7) do not demonstrate that the investigated fiavoenzymes act as vanadate reductases. They suggest an alternative mechanism in which the fiavoenzyme simply serves as a generator ofsuperoxide (02) radical, which acts as a propagator of the radical chain reaction leading to NAD(P)H oxidation (9, 10), as summarized below:

Nov 1, 1995

The twelve latexes listed in Table XI penetrated A horizon soil as shown by elution through a laboratory soil column and gave good sealing efficiency. See details in Table XII. High elution through laboratory soil columns of 4 to 6 inches depth is desirable because it predicts penetration of latex to a greater depth in the field. No definite correlation was evident between penetrating ability and particle size, surface tension, or pH. Most of the materials, however, were characterized by low surface tensions in the 36 to 53 dynes/cm range while particle sizes were usually in the intermediate range of about 1500 to 2500 Å. Naugatex J-3471 (a highly crosslinked styrene-butadiene copolymer) was the most promising of this group for stability, penetrating ability; and sealant efficiency. It also showed utility with [B] profile soil. Many of the other latexes tested in this investigation showed good sealing efficiency but were judged unsatisfactory because they gave low penetration or formed surface films with & horizon top soil. In general, latexes containing cationic surfactants were not satisfactory because they formed a heavy surface film. This is due to neutralization of the positive latex charge by the negatively charged soil particles.

Jan 1, 1972

By Thomas C. Ruhe

The Bureau of Mines conducted research to determine the safe operating conditions for using recycled (used) lubricating oil from mining equipment as a partial replacement for diesel fuel to make ANFO-type blasting agents. The use of recycled oil (RO) saves energy, reduces oil imports, and reduces mining costs. Low ambient temperatures may cause these recycled oils to become too viscous for proper absorption by ammonium nitrate (AN) prills and result in poor blast performance, safety hazards, and environmental problems. To help quantify and resolve these issues, viscosity, mixing, and performance tests were conducted at various temperatures. Diesel fuels No. 1 and No. 2 were studied separately and in blends with 25,50, and 75% RO. Good quality ANFO mixes (94-6) were produced with dry absorbent prills and blended fuel (No. 1 diesel plus RO) at temperatures as low as -40°F (-40°C) with 75% No. 1/25% RO, and at -20°F (-29°C) with 50/50. Diesel fuel No. 2 also made good mixes as low as -30" F (-34°C) with 75% No. 2/25% RO, and at 0°F (-18°C) with 50/50.

Jan 1, 2008

By Joseph Grumer

In addition to nine powder and gaseous extinguishants of propagating Pittsburgh seam coal dust-air explosions earlier evaluated,6 10 other powders have similarly been evaluated under like conditions such that wall quenching of the coal dust-air flames was virtually absent and the dust concentration was temporally and spatially uniform to within about ±5 percent. None of the newly examined extinguishants was better than Purple-K (potassium bicarbonate); the 10 of this report are anhydrite (calcium sulfate), monobasic (4 types) and dibasic ammonium phosphate, natural and synthetic cryolite (sodium fluoalumi-nate), sodium sulfate, and tricalcium phosphate. Except for anhydrite, sodium sulfate, tricalcium phosphate, and the cryolites, these materials were about equally effective, when present in relatively low concentrations (weight-percent of the coal dust-extinguishant mixture). The maximum oxygen concentration for the extinguishment of otherwise uninhibited coal dust explosions and the influence of coal dust particle size and the volatile content of the coal were also explored. For the present, the choice of the inhibitor among the good ones evaluated is not as critical as the system to be used to deploy the extinguishant against a coal dust explosion.

Jan 1, 1973

By Alan G. Mayton

A prototype end-cab shuttle car (SC) design has been developed to improve protection and address ergonomic concerns of the SC operator in low coal mines. The new design features an end cab transversely mounted to the SC and equipped with a closed-circuit video system. The end cab was retrofitted to a low-coal SC and evaluated in surface trials at the U.S. Bureau of Mines. During surface trials, test operators evaluated the end-cab SC relative to visibility; cab features-space, seating, controls, and operator position; tramming-inby, outby, and turning corners; and dumping. Trials were conducted using 12 test subjects; 6 were experienced SC operators. Results of the trials were promising. Of the experienced operators, the only operator with low-coal experience gave the new design the highest rating. Four experienced operators rated the end-cab design "better" to "much better" than a standard center-driven, side-cab SC for visibility when tramming, protection from roof and rib hazards, and no change in seat position with direction of travel. This report discusses research to modify a used 21SC JOY SC, retrofit the SC with the Bureau-developed end-cab, and evaluate the retrofitted end-cab SC in surface trials.

Jan 1, 1993

By M. M. Fine

In an experimental study by the Bureau of Mines, in cooperation with National Lead Co., the roast-flotation process was found to be an effective means of upgrading certain cobalt-nickel stockpiles. The research was undertaken to determine whether the process could yield an enriched feed, with a minimum cobalt content of 6.0 percent, for the company refinery. The stockpiles (products of the company Fredericktown, Mo., milling operations) were essentially complex sulfides of cobalt, nickel, copper, lead, and iron, 1 sample of which contained 2.84 percent Co and 3.57 percent Ni. After a controlled oxidizing roast at 400° C., laboratory flotation with conventional sulfhydric reagents yielded an enriched concentrate analyzing 9.22 percent Co and 11.43 percent Ni, with recoveries of 84.9 and 85.8 percent, respectively. These are typical laboratory data; other data indicated higher grades were possible but at reduced recoveries. A brief, continuous campaign verified the applicability of the process to the raw material in question but was not continued long enough to establish optimum conditions. As a consequence, the results of the large-scale tests did not equal those obtained in the laboratory but definitely confirm the beneficiation possible from the roast-flotation process.

Jan 1, 1958

By Paul Sands

Single- and two-stage tests were made with 6-inch, coal-cleaning hydrocyclones to determine the effect of hydrocyclone geometry, operating conditions, and feed composition on performance. Most of the testing was conducted in an open-circuit pilot plant that had a maximum capacity of about 9 tons per hour. The coals used in the investigation had top sizes of 1/4 inch and 28 mesh. Considerable latitude was found in the range of geometry variables that could be used without affecting performance adversely, although a certain minimum ratio of overflow to underflow openings had to be maintained for best operation. Two-stage cleaning proved distinctly better than operation with a single hydrocyclone, because clean coal lost in the refuse product of the primary unit can be partly recovered in the secondary. There is an unusually great difference in the specific gravities at which the individual sizes of the feed are separated in the hydrocyclone. This militates against high efficiency because maximum yield occurs when all sizes are cleaned at the same specific gravity. The size composition of the feed and, more particularly, the size composition of the impurity have a greater influence on the efficiency attainable in the hydrocyclone than in most other types of fine-coal cleaners.

Jan 1, 1968

By William D. Monaghan, Thomas H. Dubaniewicz, Kenneth L. Cashdollar

Emerging laser technologies are quickly gaining acceptance in the industrial workplace. Besides the risk of human exposure, one safety concern with the more intense lasers is the potential for ignition of flammable gases, vapors, dusts, fibers, or flyings often found in hazardous (classified) industrial settings. In underground coal mines, lasers are being considered for remote measurement of explosive methane gas. Current federal safety regulations for underground mines contain no specific guidance for evaluating the safety of optoelectronic components such as diode lasers. The National Institute for Occupational Safety and Health is conducting research to help provide a scientific basis for developing appropriate safety guidelines for optical equipment in the presence of flammable methane gas and/or coal dust. One phase of the study is an experimental evaluation of methane-air ignition by laser heated small particles. Minimum observed igniting powers for laser energy delivered by 200-, 400-, and 800-um core diameter fiber optic cables and directed onto selected targets in methane-air atmospheres were 0.6, L l, and 2.2 W, respectively. Comparisons are made with other ignition phenomena, including heated wires.

By Jr. Dubaniewicz, Gregory M. Green, Kenneth L. Cashdollar

Laser-based instruments are used in areas where coal dust ignition presents a safety hazard. The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory ~NIOSH, PRL! is conducting a study to help determine when an optical beam may be considered a potential ignition source in underground coal mines or coal storage facilities. Researchers conducted experiments to determine threshold igniting powers for Pittsburgh seam bituminous coal dust clouds using an 803 nm continuous wave laser. For fine sized coal dust dispersed in air, concentrations ranging from 600 to 2000 g/m3 were the most easily ignited. A heated layer of coal dust that deposited on the fiber tip during dispersion ignited the dust clouds. Minimum observed igniting powers for laser beams delivered by 200, 400, and 800 mm core fiber optic cables and directed into coal dust clouds were 2.0, 3.0, and 5.0 W, respectively. Threshold igniting power was proportional to beam diameter, and threshold igniting power density decreased with larger fiber diameters. Ignition delay times averaged 0.6 s and did not vary significantly with laser power under initially turbulent test conditions and with flammable targets. Comparisons are made with the results of other researchers.

By Victor J. Lynch

The Andover-Sulphur Hill mines are 12 miles northeast of Andover and 5 miles southeast of Newton, in Sussex County, N.J. The property is situated on the Lehigh Valley and Hudson River Railroad and half a mile east of U.S. Highway 206. It is connected with the main highway by a hard-surfaced county road. (See fig. 1.) Howard J. Hewitt of Lafayette, N.J., has under lease the Sulphur Hill tract, consisting of 28 acres, and has an option on the Tar Hill tract of 106 acres. The Tar Hill property adjoins the Sulphur Hill on the northeast. (See fig. 2.) The Andover-Sulphur Hill property is owned by the Lenape Corp. of Andover, N.J., while the Tar Hill tract is owned by the Crane Iron Co. of Phillipsburg, N.J. These mines produced iron ore during a period of about 100 years but have not been operated since 1880. Zinc and lead sulfides occur mixed with iron ores in the lower workings of the old mines. A diamond-drilling program was recommended to determine the extent of the sulfide mineralization in depth and also to explore further the iron-ore deposits on the property. The project was started October 6, 1942, and finished November 25, 1942.

Dec 1, 1947

By Kenneth H. Johnston

Information on oil and water production, volume of water injected, core analyses, and well completion data was collected on 28 Red Fork sand water-flood projects for comparison and evaluation of results. An average water injection efficiency of 35 percent, an average water-injected to oil-produced ratio of 16.8:1, and an average loss outside the flood pattern of approximately 45 percent of the injected fluid resulted in an oil recovery to January 1, 1969, of only 5.6 percent of the pore volume, or 9.1 percent of the initial stock-tank oil in place. The principal causes of poor oil recovery from these projects are the losses of large quantities of injection water from the flood patterns through oriented, natural fracture systems or zones of high permeability and excessive channeling of injection fluids from input wells to oil wells. For more efficient operation and a higher percentage of oil recovery from the Red Fork sand and other low-permeability-sand waterflood projects, directional orientation of both induced-and natural-fracture systems should be determined during early development. The success of a low-permeability-sand waterflood project depends to a large extent upon the orientation of the injection wells with the fracture system.

Jan 1, 1970

By Charles L. Kimbell

For 1991, the aggregate value of world international export trade in mineral commodities was roughly estimated at $685 billion in current 1991 dollars. The estimated level was about 6 % higher than that for 1990, but still more than 3 % below the record high set in 1980, and the year was the fifth in a row in which the value of exported minerals advanced. Table 8 provides a data series for the estimated value of world export trade in all mineral commodities from 1979 through 1991, as well as a breakdown of this total into fuel and non fuel commodities. The data shown are based on the historically more traditional and realistic (from the viewpoint of data availability) practice of reporting trade values for the year before the year of review. Despite the considerable increase in the dollar value of mineral commodity exports, their share of total export merchandise trade declined to 19.1 % in 1990 from 19.7% in 1989. At 19.1 %, this share was very near the recent year record low of 19.0% reached in 1988. Comparable 1991 figures were not available in time for inclusion here, but it is expected that the mineral commodity share of the total will be little altered from that of 1990.

Jan 1, 1993

This Information Circular from the National Institute for Occupational Safety and Health (NIOSH) documents and supplements the information presented in a series of workshops held during 2002 and 2003. The primary intended audience consists of all who are involved in developing and conducting miners? training. According to the Mine Safety and Health Administration (MSHA), mine operators reported 240,000 full-time equivalent workers and independent contractors reported 42,000 full-time equivalent workers working on mine property during the year 2000. Unfortunately, these workers have a relatively high risk of suffering serious work-related injuries and illnesses. The mining industry has the highest rate of occupational fatalities among all U.S. industries. The fatality rate is 30 deaths per 100,000 workers compared to 4.6 for all private industry(Morbidity and Mortality Week Report, 2001; NIOSH, 2002).Compared to workers in other industries, miners also have a relatively high rate of nonfatal lost-time injuries, and their injuries tend to be more severe (Bureau of Labor Statistics, 1999). Many miners are also exposed to significant health hazards, including coal and silica dust, diesel exhaust, and noise. More than 1000 U.S. miners die of lung disease each year(NIOSH, 1999).

Jan 1, 2002

By Maria I. De Rosa

Table 19 and figure 7 show the number of fires and fire injuries for surface coal mines by state during 1990-1999. Table 19 also shows by state the risk rates, employees' working hours, lost workdays, and coal production. For surface coal mines, 215 fires occurred in 21 states during 1990-1999. Ninety-four of those fires caused 93 injuries and I fatality (the yearly average was 21.5 fires and 9.3 fire injuries). Fourteen fires and seven injuries involved contractors. The Ewhr value was 729 x 10° hr (In = 0.026), the CP value was 6,355 x 10° st (Fn = 0.034), and the LWD value was 8,141. Kentucky had the most fires and fire injuries (45 fires and 23 injuries), followed by Pennsylvania (33 fires and 14 injuries), West Virginia (25 fires and 14 injuries), and Indiana (20 fires and 8 injuries). Among these states, Pennsylvania had the highest fire risk rate value (Frr=0.145), while Kentucky had the highest injury risk rate value (In 0.041).

Jan 1, 2004

By A. R. Rule

Laboratory tests were conducted to study removal of magnesium impurities from western phosphate rock concentrates by selective leaching. The systems evaluated included leaching with dilute sulfuric acid, with ammonium sulfate, and in an aqueous medium with sulfur dioxide gas. Set standards for the magnesium impurity level of phosphate rock concentrates are not available, but industrial practice has indicated that magnesium in excess of 0.3 percent MgO causes problems in phosphoric acid manufacture. Removal of magnesium was accomplished with all three systems. With dilute H2S04 the magnesium level was reduced to less than 0.1 percent MgO with an accompanying P205 loss of 6 percent. Magnesium oxide levels from 0.3 to 0.2 percent were obtainable with ammonium sulfate. However, the system requires concentrate roasting at temperatures of 900° C or higher, heated pulps (100° C), and large quantities of ammonium sulfate. Selective leaching was obtained using S02 gas in an aqueous concentrate slurry. Magnesium oxide content was reduced to less than 0.1 percent without loss of phosphate.

Jan 1, 1970

By Carla A. Kertis

Because coalbed discontinuities often pose serious economic and safety problems in underground coal mines, criteria were documented for the recognition and prediction of discontinuities in advance of mining. Pennsylvanian strata in Indiana and Armstrong Counties, PA, were deposited as part of fluvio-deltaic complexes with channel-phase sandstones as the predominant type of coalbed discontinuity. Coalbed isopach maps constructed for this study delineated numerous want areas (areas of no coal) with elongate to linear geometries. A comparison of coalbed isopach and corresponding sandstone isolith maps of the study area revealed many examples of a thick-sandstone, thin-subjacent-coalbed relationship. Nearly 60 pct of the want areas in the study area were found to lie subjacent to thick (> 20 ft [6 m]) sandstone accumulations. In addition to erosion of the coalbed, channels may contribute to coalbed splitting, coalbed thinning over paleotopographic highs, abnormal coalbed thick- nesses, and deterioration of coal quality. If these features are considered, then approximately 80 pct of all interruptions in the economic coalbeds in this area result from channel activity. By using the criteria developed in this study and described in this Bureau of Mines report, the occurrence of coalbed discontinuities may be predicted and anticipated in advance of mining.

Jan 1, 1985

By Lawrence L. Davis

This chapter includes tables for 1981 that were not available in time for publication of the 1981 Minerals Yearbook, but does not include corresponding tables for 1982. The value of raw nonfuel minerals produced in the United States during 1982 was estimated at about $20 billion, a decrease of $5 billion compared with that of 1981. The decline in value is the first since 1971 and is the largest percentage drop since 1938. Although the domestic mining industry continued to be troubled by difficulties in attracting capital and by import competition from countries with lower overall production costs, the principal cause of the decline was sharply decreased demand brought on by the worldwide economic slowdown. Metal commodities were impacted most severely with only 4 of 21 metals registering production value gains and only 3 of 21 showing production quantity increases. Overall metal production value decreased 37% from that of 1981, a reflection of the domestic slowdown in the automobile and construction industries, which are major metal users, Overall production value of nonmetals decreased 12% compared with that of 1981, with only 14 out of 44 nonmetals showing increases. Nonmetal production quantities increased over 1981 for only 6 of the 44 nonmetals.

Jan 1, 1983

By R. Hogg

"Particles play an important role in our environment and in many aspects of human activity. Much of the Earth's surface - sand, soil, rocks - consists of particles, as do clouds in the atmosphere, smoke from fires, and dust in our homes. Many of the foods we eat - cereals, flour, instant coffee - and everyday items such as pharmaceuticals, cosmetics, detergents and other cleaning products are encountered in the form of particles. Inks and paints consist of very fine particles dispersed in liquids. Modem agriculture uses huge quantities of fertilizers and pesticides, largely in particulate form. The list could be extended almost indefinitely; particle systems are obviously an important part of our daily lives. But what do we know about them? For most people, the answer is probably: not much.We are all familiar with the three common states of matter: gas, liquid and solid. In many respects, particle systems should be regarded as a distinct class of their own. The particles themselves may be solid but we all know that a heap of sand is quite different from a solid rock. A cloud of liquid droplets - fog - has much more in common with a cloud of solid particles - smoke - than it does with a bucket of water. There are certain characteristics and properties which are unique to the particulate state. The behavior of any particle system is determined not only by the material from which the particles are made, but also by interactions among the particles and with their environment. These interactions become increasingly important as the size of the particles decreases, and for exceedingly fine particles, smaller than about one micrometer (0.000001 meters or 0.00004 inches), these interactions dominate and we enter the realm of colloidal systems.Particle SystemsA system in which discrete entities - particles -are dispersed in a continuous medium can be regarded as a particulate system. The particles and the medium can consist of a solid, liquid or gas. The various combinations and some common examples are listed in Table 1. The properties and behavior of these systems depend on the characteristics of the particles, the nature of the medium, and the relative abundance of the two phases. In general, it is the latter which determines the kind of behavior exhibited by the system.As a general rule, the behavior of particle systems follows that of the dispersed phase (the particles) at high concentration, and that of the continuous phase (the medium) at low concentration. For example, both powders and smokes consist of solid particles in a gaseous medium. However, in a powder the solids typically occupy over one half of the total volume; in many respects powders behave like solids. In a smoke, on the other hand, the particles may take up only a few parts per million of volume, so that these systems generally behave like gases."

Jan 1, 1989

By Christopher Mark

Since it was first introduced, the Coal Mine Roof Rating (CMRR) has been widely accepted as a tool for geologic characterization and mine planning. This paper discusses the application of the CMRR to another practical ground control problem. Extended cuts (cuts greater than 6 m (20 ft) in length) are commonly used with remote control continuous miners. Extended cuts can greatly increase productivity, but they have been associated with a number of fatal roof fall accidents. When extended cuts are attempted in weak roof, the roof may collapse before it can be bolted, causing hazardous conditions. Until now, it has not been possible to predict where conditions may not be suitable for extended cuts. In this study, data on the CMRR and extended cut experience were collected at 36 mines in 7 states. It was found that when the CMRR was greater than 55, deep cuts were routine in nearly every case. When the CMRR was less than 37, extended cuts were almost never taken. Between 38 and 55, extended cuts were feasible sometimes but not others. The data also shows that extended cuts are less likely to be stable if either the entry span or the depth of cover increases.