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In laboratory tests using reconstructed soil columns, rubber latex showed good sealing efficiency when applied at a rate equivalent to 4000-5000 pounds per acre. Results of field testing, however, were inconclusive. The ideal situation in which latex would coagulate in a narrow zone two to three feet below the surface by reacting with acidic or metallic constituents of the soil was not attained. Rather, the latex was deposited progressively as it passed through the soil (most of it remained in the top foot), the rate of deposition being dependent on soil structure and composition as well as on properties of the latex such as particle size and emulsion stability. Latex stability appears to be a more critical property than latex particle size in controlling penetration. Addition of excess anionic or nonionic surfactants to latex improved its penetration into the soil. A styrene-butadiene (SBR) rubber latex of 2400 Å average particle size with high mechanical stability gave the best balance of penetrating ability and sealing capacity in laboratory tests and this was confirmed in tests on a 5 x 5 foot test plot at Lanse, Pennsylvania. This latex was subsequently applied to three one-quarter-acre plots at Lanse by sprinkler irrigation, and compared to adjacent areas that were sprinkled with water only. Soil moisture measurements did not enable us to judge the effectiveness of the seal because differences between sampling positions were greater than differences between treated and untreated sections, but permeability tests showed that water flow was much slower (90-99% reduction) within the top ten inches of soil in the latex- treated sections. This sealing effectiveness was reduced after wintering. There was no deleterious effect on the vegetation as a result of sprinkling the areas with latex. A laboratory study conducted in a 5 x 5 x 5 foot box containing uniform reconstructed soil from a New Jersey source suggests that latex penetration into the soil in the field occurs mainly through natural macro openings and not through the capillaries of the soil structure. Dilute solutions of ammonium hydroxide or sodium carbonate (with no latex present) were found to seal effectively in laboratory soil columns as well as in field applications. However, since these chemicals are water soluble, the seal is temporary. Raw material costs of latex at the application rates used in the field testing are in the order of $1000 per acre. Equipment and operating

Jan 1, 1972

By J. H. Perry, Joseph Cervik, G. N. Aul

The Bureau of Mines is conducting research to determine the effectiveness of long holes in degasifying an area of the Upper Split of the Lower Sunnyside coalbed at Kaiser Steel CO.'s Sunnyside No. 1 mine. These holes were drilled from the two outside entries of a section that was closed to mining because of excessive methane emissions. Two holes drilled to 430 and 450 feet produced initial gas flows of 160,000 and 127,000 cfd, respectively. Sixteen days after the completion of the second hole, the total gas production declined to just over 144,000 cfd. In 9 months of degasification, over 35 MMcf of commercial-quality gas has been removed from the coalbed. The combined gas flows declined to 106,000 cfd in the 9-month period. The two holes have reduced face emissions by about 40 pct.

Jan 1, 1978

By J. Hudy

The performance of six dense-medium washers was evaluated in five preparation plants. Three of the plants were making a two-product separation that produced a clean coal and a refuse; one plant employed dense-medium vessels in series to effect a primary and a secondary separation; and one plant was equipped with a two-compartment washer effecting two separations in one vessel. The separate secondary drum-type washer produced a low-ash metallurgical coal and an intermediate-ash product suitable for plant fuel or steam generation. The two-compartment washer produced a premium anthracite product and a middlings product. The sharpness-of-separation values ranged from good to excellent for the five primary separations and for the secondary separation.

Jan 1, 1968

By John C. Edwards

Chapman-Jouguet detonation calculations were carried out for pentaerythri-tol tetranitrate (PETN), TNT, and ammonium nitrate-fuel oil (AN-FO) explosives using the compressibility form of an equation of state of hard spheres based upon Percus-Yevick (PY) theory, and a chemical equilibrium detonation code called TIGER. Similar calculations were also carried out with the Becker-Kistiakowsky-Wilson (BKW) equation of state. For PETN, the BKW equation gives somewhat better agreement with experimental values of detonation velocity and pressure. However, in terms of experimental temperatures and concentrations of the minor product species (NO), the predictions of the PY equation are shown to be more satisfactory. Similar comparisons of experimental and theoretical results for TNT and AN-FO indicate that the PY equation has general utility in predicting the detonation properties of condensed explosives at moderate loading densities (Po < 1.3 g/cm3).

Jan 1, 1974

By Sarah P. Guerrino

This chapter summarizes data on crude nonfuel mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are the tables that show the principal nonfuel mineral commodities exported from and imported into the United States and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of Volume I and in the State chapters of Volume II of this edition of the Minerals Yearbook. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in this chapter is what is normally termed ?mine output.? It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the output from auxiliary processing at or near the mines.

Jan 1, 1987

By D. E. Seizinger

Analytical methods for oxygenates in exhaust gases were studied, and emissions of these compounds from automotive engines were measured with and without an oxidation catalyst in the exhaust system. Hydrocarbons, simple mixtures of hydrocarbons, and a single gasoline were used as fuels. With the more complex gasoline, successful analysis was possible only with exhaust from the catalytic system which preferentially converted and thus removed interfering hydrocarbon species. However, it was shown that an estimate of the oxygenate yield from gasoline used in a noncatalytic system can be synthesized from data obtained with simple fuels. Such synthesized data were used for comparison of noncatalytic with catalytic systems. Compared with those of previous studies, results of this work indicate that the action of the catalyst introduced no new oxygenates and reduced both the carbonyl and the total of oxygenates. It is concluded that the compositional character and class distribution of oxygenates in exhaust from catalytic systems may differ significantly from the composition and distribution for oxygenates not subjected to catalytic conversion. The findings also support previous estimates that noncarbonyls may constitute a significant fraction of exhaust oxygenates and may warrant attention in procedures for measurement of the oxygenates.

Jan 1, 1973

By B. G. White

NIOSH researchers have identified a pattern of fracture zone development that suggests an explanation for fracture formation around rectangular openings in underground mines. This pattern is characterized by shearing and dilation that result in either faults or in the repeated formation and propagation of en echelon fractures from sites of tension. Two computer modeling codes, Fast Lagrangian Analysis of Continua (FLAC) and Particle Flow Code (PFC), were used to model different aspects of this pattern. Use of very small elements with FLAC enabled the identification of sites of initial tension near the skin of square-cornered rectangular openings, while PFC allowed the initiation and progressive development of fractures from these sites to be followed as the fractures evolved. Such studies can lead to a greater understanding of how roof support can be better selected and installed for specific conditions in underground mines prone to roof falls and rock bursts. These studies may also lead to modifications of corner and opening shapes that could be incorporated into mine designs to produce more stable mine openings and reduce the risks of rock falls and rock bursts.

By McHenry Mosier

Although local conditions at each mining property affect the percentage of increase in drilling speed for a given reduction in gage of bit, the results of drilling tests conducted at the Mount Weather testing adit show such a large advantage in favor of the smaller gages that they should be indicative of the possibilities at most mines. GENERAL DISCUSSION Although it is common knowledge among miners that drilling speed ill- creases with reduction in gage of bit, the large amount o this increase is not so universally realized, A recent Bureau of Mines4/ survey of drilling practices in 28 metal mines showed that the maximum gage of starters is 3 inches and that at 50 percent of the mines starters are 2-1/4 inches or larger, Because this size appears too large for conditions at most&apos; mines where abrasion is moderate and where powder distribution permits, the use of smaller bits presents a favorable opportunity for reducing drilling costs.

Jan 1, 1939

By J. D. Corrick

Research was conducted to develop operating techniques and define some of the limiting parameters for microbially converting hydrous calcium sulfate to hydrogen sulfide. The work was carried out in either glass stoppered flasks or anaerobic fermentors. Using the criteria of pH, temperature, number of bacteria per milliliter of test solution, and hydrogen sulfide produced, it was shown that hydrous calcium sulfate could be microbially converted to hydrogen sulfide at a rate of 7.3 g H2S/1 of fermentor volume per 24 hours. The various parameters defined were pH, temperature, and medium exchange rate. These were shown to be a pH range of 7.2 to 8.8, a temperature range of 30° to 35° C, and a medium exchange rate of 70 percent of the ferment or volume per 24 hours. It was also shown that a daily waste was between 50 and 77 percent as effective as sodium lactate in supporting the production of hydrogen sulfide and that by utilizing a gas to purge the fermentation system, a 1.7-fold increase in hydrogen sulfide was obtained.

Jan 1, 1970

By J. K. Whyatt, B. G. White

Various methods of monitoring slip movements on bedding planes, as well as examination of rock burst damage in stopes, suggest that many rock bursts in the Lucky Friday Mine are closely associated with these movements. Slip displacements along bedding simultaneously reduce the physical dimensions of stopes and increase compressive stress along stope margins. Such changes, in turn, contribute directly to sudden failures of rock and cemented sandfill surrounding stopes. We believe that the reduction of rock burst hazards must be based on a clear understanding of the basic mechanisms involved. The current work emphasizes the mechanical role of wall rock movement and seismicity in generating conditions that promote rock burst damage. Based on our interpretations of these mechanisms, we briefly address several hypothetical practices that could influence rock burst hazards in similar mining situations. The overall goal of this research is to advance the NIOSH mission of improving the health and safety of the nation’s workers.

By Theodore Christos

The Bureau of Mines sponsored an investigation of the thermal oxidative degradation characteristics of selected ingredients employed in the formulation and manufacture of conveyor belts. This work was done to supplement similar studies of samples from finished conveyor belts and thus provide basic data for correlation of the potential toxic behavior of a finished belt with that of the individual ingredients. This report covers the study of (1) basic polymers (styrene-butadiene, neoprene), (2) reinforcing fibers (Nylon 6,6, Dacron, viscose rayon), (3) flame-retardant plasticizers (tritolyl phosphate-isomeric mixture, tri-p-tolyl phosphate, tributyl phosphate, tris (dichloropropyl) phosphate), (4) plasticizers (diphenylphtha1ate, di-(2-ethylhexyl) sebacate), and (5) a vulcanization accelerator (2-mercaptobenzothiazole).

Jan 1, 1977

By R. L. Montgomery

The heats of formation of lanthanum sulfate and the enneahydrate are -939.8 ± 3.1 and -1,587.1 ± 3.2 kcal. per mole, respectively. The heat of hydration is -32.5 ± 3.5 kca1. per mole. These values were obtained from heat-of-solution measurements of lanthanum oxide and salts. Low rates of solution precluded more accurate determinations of the thermal data. The heat of formation of the chloride was similarly observed to be -256.18 ± 0.28 kcal per mole. Heats of solution and combustion of lanthanum metal yield mutually concordant results, and earlier discrepancies reported in the literature may be ascribed to impurities.

Jan 1, 1959

By Gregory J. Chekan

In This Chapter [Drilling, blasting, and crushers Diesel particulate Enclosed cabs Ventilation with jet fans Stopping construction methods Propeller fans as main fans] This chapter explains how to control dust in large-entry stone mines, including both silica dust and diesel particulate. Most stone mines are limestone mines, but a substantial minority are marble, sandstone, and granite mines. These mines differ from most others in that entry widths are 30 ft or more and entry heights are 25 ft or more. Such mines, developed with room-and-pillar methods, have large open areas that can make ventilation and dust control more difficult. Because of the difficulty of ventilating stone mines, improved ventilation is a major focal point of this chapter. However, the chapter also covers the control of dust from drills, blasting, and crushers. Another part of the chapter covers enclosed cabs, an effective dust control technique for some workers. BACKGROUND The major dust compliance problem in stone mines is caused by silica (quartz) in the rock. Mines in high-silica rock, 8% or more, are far more likely to have a dust problem than those where there is less silica. Geographically, the limestone in the Northeastern and South Central United States has higher silica than the rest of the country. Chekan and Colinet [2002] have analyzed Mine Safety and Health Administration (MSHA) dust sampling results [MSHA 2001] from the stone industry. They have concluded that, on average across the United States, the workers exposed to the highest dust concentrations are rotary drill operators, front-end loader operators, truck drivers, and crusher operators. However, there are many regional differences. Also, occupations that work outside of cabs, such as blasters, roof bolters, and laborers, can be exposed to high dust levels.

Jan 6, 2003

By Paul E. Loustaunau, Devah Galloway, Catherine Wetherby

This report describes a project in which Development of a Supervisory and Management Training Program for the Underground Coal Mining Industry was developed and evaluated. The project was carried out in two phases. The first phase was a research effort to develop specifications for the program. The second phase was a development and evaluation effort. In the second phase, training programs for first-line supervisors (section foremen) and for middle managers (mine/shift foremen and mine superintendents) were prepared in accordance with the specifications and evaluated by members of the industry. This report describes the project and presents the conclusions drawn there from.

Jan 5, 1983

By R. E. Perry

In connection with a program of coal research at the Southern Experiment Station the Bureau of Mines, in cooperation with the University of Alabama and the various coal operators, conducts washability studies of coal from beds in Alabama and other Southern States in which commercially important deposits occur. One of the main objectives of a washability study is to obtain technically and commercially important data necessary for determining the best methods for preparing and utilizing the Nation&apos;s limited reserves of coking coal. Such information is important to conservation because it facilitates selection of preparation methods that will provide maximum yields of coal with low ash and sulfur contents.

Jan 1, 1958

By Edward D. Thimons

The Bureau of Mines conducted in-mine tests to determine correction factors applicable to low-velocity airflows (below 150 fpm) measured by the smoke cloud, vane anemometer, and oil of wintergreen tracer gas techniques 0 The average correction factors found for these methods of measurement were lower than those reported in the literature for use with higher velocity measurements. All tests measured airflows with controlled average velocities ranging from 50 to 100 fpm. Correction factors averaged about 0.75 for readings taken by the centerline smoke cloud method, remotely controlled and stickheld center" line anemometer, and split traverse stick-held anemometer. For hand-held centerline anemometer and oil of wintergreen tracer gas readings, correction factors averaged about 0.67. Since special anemometers are needed to measure airflows in this low-velocity range, and since proper calibration of these anemometers is difficult and expensive, the use of anemometers for low-velocity measurement is imprac-tical. On the other hand, smoke and oil of wintergreen give results as con-sistent as those obtained with specially calibrated, low-velocity anemometers. Furthermore, they are easy to use and inexpensive.

Jan 1, 1979

By Jay F. Colinet, John A. Organiscak

In This Chapter [Which dust source to address first How much air and water are needed Keeping dust out of the walkway Moving workers upwind Dealing with the stage loader-crusher Gob and wing curtains to aid airflow The shearer-clearer system Modified support movement practices and Dust control for future longwalls ] Controlling longwall dust is not easy. Longwall production levels are high, and there are several different sources of dust to contend with. If dust levels are high, the initial effort should be devoted to finding which source is the cause. Then, efforts to reduce dust can be concentrated where they will have the most impact. To control dust at longwalls, a large amount of ventilation air and spray water must be used. The water must be sprayed correctly so as not to blow dust into the walkway. Techniques to change local airflow patterns can be helpful. The shearer-clearer, as well as gob and wing curtains, are examples of such techniques. DECIDING WHICH DUST SOURCE TO ADDRESS FIRST [If a longwall is out of compliance with dust standards, knowing where the extra dust is coming from helps to get back in compliance quickly.]

Jan 6, 2003

By S. E. Khalafalla

The extremely sluggish oxidation of steel scrap was appreciably accelerated when the charge was pretreated in aqueous solutions of sodium metavanadate or sodium molybdate. The degree of oxidation acceleration was inversely correlated with the melting point of the promoter oxide possessing the highest valency. The magnitude of oxidation enhancement exhibited a systematic inverse dependence on the duration of pickling processes; mere dipping of the oxidizable charge in the vanadate bath was most effective. In general, the rate of steel scrap oxidation increased with increasing concentration of the pickling reagent. The results are explained on the basis of the hydrolytic decomposition of the pickling agent with subsequent slow interaction with the metal surface, coupled with the tendency of vanadium to form polyanions in alkaline media. The data not only served to elucidate the mechanism by which catastrophic oxidation takes place, but also showed that the accelerating species need not be alloyed with the oxidizable metal; surface impregnation by minute amounts of the accelerating species can still produce catastrophic effects.

Jan 1, 1970

By George E. Fasching

The Bureau of Mines has developed a pulse counting system with improved energy resolution and having dual channels to process pulses at different rates and a pulse pileup detector for channel selection. Pulse input is delayed until the detector determines if any pulse is so closely followed by a second pulse as to constitute pulse pileup. If no pulse pileup is detected, the slower channel is selected; this clips the pulse to a wide pulse width to retain good energy resolution. If pulse pileup is predicted, the fast channel, with correspondingly shorter pulse width, is selected to improve resolution with respect to time. Output of the two channels is transmitted to a pulse height analyzer for interpretation. The pulse processing system can process count rates above 300,000 counts per second with little loss in energy resolution.

Jan 1, 1974

By Elizabeth A. Johnson

The effect of slag composition on lead losses to slags and on the behavior of associated accessory elements in lead blast furnace smelting has been studied by the Bureau of Mines. Equilibrations of 30 g of lead and synthetic slag doped with Cu, In, TI, and Sb at 1,200° C in CO-C02 atmospheres revealed the importance of the FeO:Si02 ratio and the basicity ratio, (CaO+MgO):SiO2, of the slag. Lead losses to slags increased with an increasing FeO:Si02 ratio and decreased with an in-creasing basicity ratio. Copper and indium distribution coefficients, [Lx =] increased from 15 at the lower basicity ratios to near 60 at higher basicity ratios. LTI values increased from 20 to 150 as slag basicity increased. Lcu, Lin, and LTI were relatively in-dependent of the FeO:Si02 ratio, but increased with greater amounts of accessory elements in the system. Antimony distribution alone was shown to be strongly affected by FeO:Si02 ratio, although data were scattered. LSb values ranged from 20 to 800 and decreased sharply with increasing FeO:Si02 ratios. The basicity ratio and the level of accessory element load did not have any noticeable effect on LSb.

Jan 1, 1983