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By M. M. Myers

"Importance pf the small stone problem.Profitable disposal of limestone too small for making lime in the shaft kiln, is one of the most urgent problems in the lime industry. Reports received by the Bureau of Mines from 31 quarries show that the proportion of small stone varies from 2 to 40 per cent, averaging 18 per cent of gross pro¬duction, Modern methods of heavy blasting, and the use of crushers in large quarries tend to increase the proportion of small stone above that produced in early days when light blasting and hand sledging were almost universally used. There is also a growing movement toward underground operation of lime deposits, a method which in general produces a greater proportion of fines than is encountered in open-pit work. Thus the small stone problem is of growing importance, and demands the attention of every progressive lime producer. As the problem is of almost universal interest, it is urgently desired that every operator who reads this report will contribute from his knowledge or experience, answers to the questions on the final sheet.There are several markets in which small stone may be sold but in these markets the competition is generally keen and the prices low. The lime producer's chief product is lime, he understands its manufacture and marketing, and brings him a greater return than can be obtained from most limestone by-products. For these reasons it is evident that the conversion of small into lime is the nest desirable means of disposal."

Apr 1, 1924

By David F. Smith

[The U. S. Bureau of Mines at its Pittsburgh Experiment Station is frequently called upon to determine by laboratory tests the explosibility of suspensions in air of various dusts encountered in mines and elsewhere. Not all dusts which are combustible or contain combustible material will form explosive mixtures with air under ordinary conditions of temperature and pressure. They may not be highly combustible enough. They may contain a considerable amount of inert or non-combustible material or, the dust particles may not, be fine enough to form explosive mixtures. A knowledge off the chemical composition of a dust together with a determination of the size of the particles often gives valuable indications. But in many cases actual explosibility tests are necessary. Such a case is evidently that of powdered soap, whose explosibility hazard the Bureau was recently called upon to determine, Although an explosion which occurred in a soap plant as early as 1890 was attributed4 to powdered soap, it is apparent, due to the great number of inquiries received by the Bureau, that the hazard presented by powdered soap has not been at all generally appreciated. To the writers' knowledge, no extensive investigation of the explosibility of powdered soaps has been made. It is only recently that pure powdered soap has been manufactured on a large scale. The familiar "soap powder" in the past was usually a mixture of soap with a relatively large quantity of sodium carbonate. Often it contained large amounts of moisture and abrasive material. Even a highly combustible dust when mixed with large quantities of inert dust will not form explosive mixtures with air. Pure powdered soap, however, presents a different aspect. Pure soap is formed by combination of alkali (incombustible material) with fatty acid (combustible material). Toilet soap fray also contain a certain amount of glycerin and essential oil winch, being combustible influence the explosibility]

Jan 1, 1928

By R. M. Winslow

"The phosphorus content of an iron ore is a determining factor as regards the value of the ore and also its metallurgical treatment. If some method of treatment, such as concentration, leaching, etc., could be used and the phosphorus con- tent of the ore reduced, it would be an important advancement in the iron mining industry towards the utilization of high phosphorus ores. Large bodies of material toe high in phosphorus to be marketable under present conditions would be made available, and a great deal of ore from the Cuyuna Range and other places, which is relatively high in phosphorus but otherwise suitable for making spiegel, could be reduced in phosphorus content sufficiently to permit its use in furnaces producing speigel.The form in which phosphorus occurs in iron ore is a much disputed question and it probably varies with the type and location of the ore. The statement has been made that ore piles on long exposure to the atmosphere often decrease in their phosphorus content. (Emmons, S.F. - Ore deposits, 1913, p. 652; Leith, C.K., Mesabi iron bearing district, U.S.G.S. Monograph 43, 1903, p. 275) There is described below experiments on the leaching of iron ores high in phosphorus, to determine whether it was economically possible to reduce the phosphorus content appreciably by leaching. As the research had a practical as well as a theoretical application, only low concentration of acids and alkalies were used.A number of variables were tried, among these being: (1) The solvent used, (2) strength of the solvent, (3) volume of solution used, (4) time ore was agitated (5) type of ore, and (6) screen size of the ore. The amount of ore taken was kept constant."

Jul 1, 1921

By Geo. Adams Roalfe

THIS PAPER is one of a series being pre¬pared for and published by the United States Bureau of Mines describing, methods of mining and crushing and the costs of operation at commercial crushed-stone plants throughout the country. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent operating expenditures only and not total costs. It is recognized that publication of total costs might in many instances cause embarrassment to individual operators, as well as to the industry as a whole. On the other hand, operating, costs are essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. Acknowledgments The author wishes to acknowledge the [ ]

Jan 1, 1932

To provide a means for rapidly evaluating proposed mine layouts in order to avoid potential hazards while minimizing loss of coal. The Approach: Development of a computer program that will compute many possible mine layouts by changing the mine plan until the arrangement giving minimal hazards with optimum extraction is found. How It Works: The Hazard Evasion Program for Mine Planning, developed by the Bureau's Denver (Colo.) Mining Research Center, tests hundreds of possible solutions to a mining layout, and by sorting out the 10 best (based on the criteria of maximum safety for workers with minimum abandoned coal), limits the number of choices that need to be considered and appraised for applicability to a given mine scheme. The program is applicable for room and pillar or longwall mining, for oil and gas well hazards, and for other hazards that can be described mathematically such as channel sands, potential bad roof areas, faulting, voids, or water pockets.

Jan 1, 1974

By Joseph Chalmers

[Stimulative methods of production, whereby the total recovery of oil from natural reservoirs is increased, have come into considerable prominence during the past 15 years. In many oil-producing areas properties considered ready for abandonment by ordinary producing methods have responded to some form of stimulation, and their economic lives have been extended. The stimulative method having widest application is the injection of air or gas into the reservoir formations through selected input wells and is commonly referred to as the ?gas drive." As a result of the many successful "gas-drive" operations operators are depending more and more upon this method for increasing the ulti¬mate recovery of oil from their properties. A number of factors influence the efficiency of different gases as propulsive agents in recovering oil from sands. Gases of high density and viscosity shrew a tendency toward a slightly higher efficiency than those of lower density and viscosity. The solubility of the gas in the oil also affects the efficiency of oil recovery. Not only does dissolved gas decrease the viscosity of the oil, but dissolved gas that expands from solution in the oil tends to increase the effectiveness of a "gas drive." Interfacial tension between the oil and the gas and its effect upon the recovery of oil by gas injection are factors of which little is known. Dr. A. G. Loomis5 expressed the opinion that interfacial tension probably plays a minor role in the recovery of oil, except under conditions that produce a gas-oil foam. In connection with the above physical properties that influence the action of a pressure medium, control of the injected volume of the pressure medium is perhaps the major factor. The rate ofg;as injection determines to a great extent the amount of slippage and the resulting efficiency of the operation. The importance of volume control is realized when one considers that frequently it is the only factor that is under complete control of the operator.]

Jan 1, 1930

By J. W. Paul, A. C. Fieldner

"In cooperation with the New York and New Jersey State Bridge and Tunnel Commissions, the Bureau of Mines has just completed the construction of an experimental tunnel in the Bureau's experimental mine at Bruceton, Pa., near Pittsburgh, Pa. The purpose of this tunnel is to make a final study of the ventilation problems arising in the adequate ventilation of vehicular tunnels for automobiles and trucks, especially the 9000-foot tubes that are being designed. to handle the traffic between New York City and New Jersey under the Hudson River.Chief engineer, Clifford M. Holland, of the Tunnel Commissions has shown that there are three principal problems involved in planning the ventilation of this tunnel, namely - (1) The amount and composition of exhaust gases from motor vehicles; (2) The dilution necessary to render these exhaust gases harmless; (3) Determination of coefficients of airflow and horse-power required in ducts, bends and openings.Composition of automobile exhaust gases.The answer to the first problem was obtained by making road tests on 101 automobiles and trucks at the Pittsburgh experiment station. These machines were taken from service without any previous adjustment so that the composition and amount of the exhaust gas may be taken as representative of actual operating conditions prevailing in the tunnel. A report covering the results of these tests was submitted to the chief engineer of the Tunnel Commissions, on November 1, 1920, and 411 be published in the report of the commissions. Several papers a have also been published in the technical journals summarizing the important results as regards tunnel ventilation and also with reference to gasoline losses in present-day motor car operation due to the general use of unnecessarily rich mixtures"

Oct 1, 1921

By Charles L. Kimbell

Available statistics on 1991 worldwide consumption of selected non fuel mineral commodities shown in table 12 indicate downturns for all but 3 of the 15 listed commodities. It should be stressed that in most instances, the consumption declines were primarily the result of lower levels of use in the former U.S.S.R. and the former centrally planned economy nations of Eastern Europe. However, several commodities suffered use cutbacks in market economy countries. In the case of the nonferrous metals covered In the table, the differences in performance between market economy countries and the former centrally planned economy states are immediately evident from the table itself. Among these important commodities, refined lead, primary magnesium, and refined tin registered downturns for market economy countries as well as among the centrally planned economy countries. Also notably, cadmium use showed no significant change from 1990 levels in either group of countries. Global consumption of iron ore fell by 3.4 % or about 31 million tons, and this was a greater decline than that logged for production of marketable iron ore and related products, which was down by only 3.0% or almost 28.2 million tons. Thus, it would seem that for another year there was a net addition to stocks. The 1991 drop in iron and steel scrap use was about 5.5 % or about 18 million tons, on the percentage basis somewhat greater than the 4.8% or 36.9 million ton drop in global steel production. Although consumption of iron ore and iron and steel scrap are not broken down by region in table 12, it seems almost assured that the pattern of 1990 continued into 1991: drops in use in the former U.S.S.R. and Eastern Europe were the overwhelmingly dominant declines and accounted for much, although not all, of the global decline, whereas among market economy countries as a group, there were upturns for both materials. On a global basis, it would appear that the slight shift in the ratio of pig iron to scrap in steel furnace charges noted in 1990 continued into 1991, this shift being toward a slightly larger proportion of pig iron with a corresponding decline in the share accounted for by scrap.

Jan 1, 1993

To provide a simple means for rapidly checking methane concentrations at working faces in coal mines while remaining under permanently supported roof. The Approach: A light telescopic probe, through which a gas sample can be pumped Into a methanometer, has been developed. See Figure 1 [ ] How It Works: The telescopic probe consists of sections of small stainless steel tubing encased in sections of lightweight fiberglass tubing. When fully extended the probe is almost 19 ft. long; fully closed it is approximately 5-1/2 feet long. It can be used In either of these positions as well as at intermediate extensions. An approved methanometer is clamped to the probe by a support bracket.

Jan 1, 1975

By T. Whitrnoyer, J. Sneckenberger

"The acOustic impedances of seven rat lungs were measured at frequencies between 100 and 6400 Hz. Rats were divided into two groups: a silica exposed group (N=3) and a control group (N=4). The silica exposed group was injected intratracheally with silica solution. Three of the control group were intratracheallyinjected with saline. Between four and six weeks after theinjections, all lungs were excised and degassed. Lungs were,suspended in a pressure Chamber, with the trachea canula attached to the end Of a tapered impedance tube. The lungs were subjected to transpulmonary pressures between -30 cm H2O and 6 cm H2O to simulate deflation and inflation. With transpulmonary pressure being held constant, the impedance tube was excited with random noise. A dual channel analyzer calculated H12(f), the transfer function between the two microphones. This function was used to calculate the lung's impedance at that pressure. The impedance magnitude spectra of both groups typically had peaks at 2000,3500, and 5500 Hz. Statistically significant differences. (90%confidence level or greater) between the two groups occur at the 3500 Hz peak at transpulmonary pressures of 20, 8, 6, 4, and 2 cm of H2O. This fact seems to confirm that this method can detect. lung disease. Further research will indicate whether this method will be able to detect the onset Of coal worker's pneumoconiosis.INTRODUCTIONOne of the first studies of impedance Of the human lung were conducted by DuBois et al.[2] using the forced OscillatiOn technique. This technique, however, was limited to frequencies below 30 Hz. Further studies by Van Den Berg [6] revealed thatthe lung reflected higher frequency sounds (100-10,000 Hz), instead Of behaving as an anechoic termination. This discovery has lead to several studies of the acoustical properties of both human and animal lungs at high frequencies [3,4,5]."

Jan 1, 1988

By C. P. Lazzara, R. A. Franks, G. F. Friel, J. C. Edwards, J. J. Opferman

A National Institute for Occupational Safety and Health’s (NIOSH) mine fire detection re-search project was undertaken to evaluate multiple mine fire sensor types for nuisance alarm discrimination. The response of multiple fire sensor types to three small coal fire and three small conveyor belt fires in the presence of diesel emissions was evaluated in NIOSH’s Pittsburgh Research Laboratory (PRL) Safety Re-search Coal Mine (SRCM). An array of fire sensors which included an optical and ionization smoke sensor, a chemical cell CO sensor, and Metal Oxide Semiconductor (MOS) sensors, was used to sample the diesel engine and fire source emissions. The mine fire detection experiments demonstrated the ability of a MOS sensor with a bimodal response to NOx and products-of-combustion (POC) to respond to the onset of smoldering combustion in the presence of CO and POC particulates from a diesel locomotive. As part of an in-mine evaluation in an operating coal mine, the MOS NOx responsive sensor and an ionization smoke sensor was demonstrated as a method to discriminate diesel emissions and cross-interference of H2 on a CO chemical cell fire sensor at a battery charging station. The reinforcement of mine fire sensor information with the use of multiple sensor types, such as an MOS sensor and ionization and optical smoke sensors, is shown to be important for nuisance alarm discrimination and early mine fire detection.

To quickly and reliably assess the stability (safety) of saturated and unsaturated tailings pond embankments. Approach Determine embankment geometry and soil properties, then use that data to obtain the safety factor of the embankment directly from one of a series of factor-of-safety charts.

Jan 1, 1982

By Roy L. Wilfong

Surface area measurements were conducted on cadmium sulfide powders following thermal treatments at temperatures up to 500° C and treatment times up to 1 week. Thermal treatments at temperatures up to 300° C produced no significant changes in the surface area of the powders even after 1 week of exposure. At 500° C some decomposition of the cadmium sulfide occurred.

Jan 1, 1970

By W. D. Haselton

This paper dealing with the mining methods used in producing iron ore from an underground operation located in the central-western part of the Mesabi Range in Minnesota is one of a series being prepared by the Bureau of Mines on mining practices, methods, and costs in the various mining districts in the United States. The mine here discussed was laid out in accordance with a plan adapted to a rather unusual type of ore body, the nature of which is such that the mining method necessarily differs in certain respects from the method used at most of the mines in this district. A description of it may therefore be of interest.

Jan 1, 1930

By J. Brad Seymour, Mark K. Larson, Richard L. Rains, Douglas R. Tesarik

For several years, researchers from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) have been using geotechnical instruments in underground mines to study ground control problems and develop means of reducing accidents and fatalities caused by ground falls. This paper describes many of the different types of instruments, sensors, and data acquisition equipment that have been used for these studies; briefly explains the advantages and disadvantages of various sensor technologies; provides practical recommendations regarding the use of specific instruments and data acquisition systems; and outlines a general approach to the design and implementation of a successful instrumentation plan. A wide variety of instruments are commercially available for measuring deformation, strain, stress, and/or load. If used correctly, these instruments can provide important quantitative information regarding the mining-induced behavior of the host rock, the performance of ground support systems, and the safety and stability of underground workings. Data collected from these instruments can warn mine staff of impending ground control failures or hazardous working conditions, as well as provide valuable information for the design of ground support systems and the configuration and sequencing of mining excavations. We hope that the practical information presented in this paper will encourage a more widespread use of geotechnical instruments in underground mines and lead to reliable measurements that aid the engineering decisions affecting the safety of miners.

Jan 10, 2000

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.

Improve the accuracy of commonly-used mine air velocity measurement techniques. Approach The Bureau of Mines, through a contract with Ketron, Inc., conducted a detailed study to establish appropriate, generalized correction factors for commonly-used air velocity measurement techniques. The techniques used were centerline readings, continuous traverse and split traverse vane anemometer readings, and smoke cloud readings (see Bureau of Mines Bulletion 589 for details on the proper use of these techniques). The various measurement techniques were used at different mine test sites to measure different air velocities. The data collected from the test sites were used in a statistical analysis which determined a generalized correction factor for each measurement technique. The correction factor multiplied by the measured velocity was used to provide the true velocity.

Jan 1, 1984

Provide means for rapidly re-establishing ventilation control in metal mines after blasting, for emergency applications, and for routine temporary use. Approach Two quickly-installed, parachute-like stoppings have been developed and tested by the Bureau's Pittsburgh Mining and Safety Research Center. How the Parachute Stopping Works The parachute stopping can be fastened to an existing anchor point, opened, and effectively block the air flow, in less than two minutes. Because the parachute stopping tends to be self-scaling, its performance is generally better than that of conventional fabric stopping. However, the periphery of the parachute stopping must be longer than the periphery of the mine opening, Figure 1 shows the parachute stopping deployed in a mine entry. To reduce leakage during routine use, the cloth at the periphery of the parachute stopping can be adjusted and then anchored at several points as necessary. This extra adjustment can also be done after the initial installation during mine rescue or mine recovery.

Jan 1, 1977

By J. F. Barkley

"In trying various coals at one of the Government power plants, comparison was made of the ash softening temperature of each coal, with the clinkering tendencies of the coal when burned in the furnace. The proximate analyses, ash softening temperature and plant reports as to clinkering were tabulated. It was desired to bring out any correlation that might appear between the ash softening temperature found in the laboratory, and the clinkering of the ash as found in the boiler furnace.Each coal used was sampled and analyzed, and the standard ash fusion test made. The clinkerring of the coal in the furnace was observed by the furnace operator. The furnace equipment consisted of the ""V"" or Murphy type of stoker with the ordinary fire-brick arch roof. With such arrangement very high furnace temperatures are apt to be produced at the ratings carried at this plant.The softening temperature of ash is defined as the temperature at which small cone of the ash, as tested in the laboratory furnace, has fused down to a spherical lump, The softening interval is the difference between the softening temperature and the temperature at which the first rounding, or bending, of the apex of the cone takes piece. The flowing interval is the difference between the softening temperature and the temperature at which the ash has reached a fluid condition as shown by spreading out over the base in a flat layer.While the analyses of the different samples of the some coal did not vary appreciably, the ash softening temperatures were not always so consistent. It will be noted from the following examples that the ash softening temperatures of different samples of the same coal differ as much as 290° F, Hence, in order to judge this property of a coal, many samples ore desirable, taken from many different shipment."

Aug 1, 1924

The National Institute for Occupational Safety and Health (NIOSH) recommends that occupational exposures to respirable coal mine dust and respirable crystalline silica* be controlled by complying with the provisions presented in this document. These recommendations are designed to protect the health and provide for the safety of workers exposed to respirable coal mine dust and respirable crystalline silica for up to 10 hr/day during a 40-hr workweek over a working lifetime. The information presented in this document demonstrates that underground and surface coal miners are at risk of developing simple coal workers' pneumoconiosis (CWP), progressive massive fibrosis (PMF), silicosis, and chronic obstructive pulmonary disease (COPD). Adherence to the recommendations in this document should prevent or greatly reduce the risk of adverse health effects in workers exposed to respirable coal mine dust and respirable crystalline silica. NIOSH recommends that preventive efforts be focused primarily on reducing worker exposures. Effective health and hazard surveillance and medical screening are also useful components of a comprehensive prevention effort.

Jan 1, 1997