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By M. B. Boyer, C. H. Herty, F. A. Hartgen, G. L. Frear

"DEFINITION OF VISCOSITYViscosity has been defined as the resistance experienced by one portion of a liquid moving over another portion, such as one molecular plane moving over an adjacent plane. A measure of viscosity is the force required to keep one plane in motion at Unit velocity, the other plane being considered stationary. Figure 1 illustrates the general idea that the surface friction between two adjacent areas will be greater the larger the molecules. Therefore it may be assumed that viscosity will be increased by molecular association or agglomeration, and likewise dissociation rill decrease viscosity. According to Maxwell (1)6 the unit of viscosity, the poise, is the tangential force per square centimeter of area of either of two horizontal planes 1 centimeter apart, one of which is fixed while the other moves with unit velocity, the space between being filled with viscous liquid of unit viscosity.The need for a satisfactory apparatus and experimental procedure for the determination of viscosity of high-melting materials at temperatures corresponding to those in pig-iron and steel making has been recognized during the past few decades. The condition of the slag during the smelting and refining periods in the iron- and steel-making processes exerts an important influence on the metal product obtained, this slag condition really meaning the state of viscosity or, vice versa, fluidity, which the slag attains under certain conditions."

Jun 1, 1934

By Raymond W. Hiteshue

Experiments were conducted al temperatures of 480° to 800° C. and hydrogen pressure of 6,000 p.s.i.g. to determine the effect of coal residence time on the conversion of a high-volatile bituminous C coal to liquid and gaseous products when using a semicontinuous apparatus designed fur rapid heating and cooling of reactants. The objective of the studies at high temperatures was to determine if appreciable quantities of coal could be converted to gaseous hydrocarbons and low-boiling liquid hydrocarbons. Experiments at lower temperatures were designed to indicate shifts in product distribution with respect to temperature and to learn more about the general mechanism of the reaction when using close control of coal residence time. One percent molybdenum, based on m.a.f. (moisture-and ash-free) coal, was used throughout this investigation. At 800° C., 6,000 p.s.i.g., and "zero" residence time) the yield of gaseous hydrocarbons was about 38 percent and the yield of oil about 4.5 percent, based on m.a.f. coal. With IS minutes residence time, under the same conditions, the yield of gaseous hydrocarbons was approximately 80 percent with no increase in yield of oil. Apparently at 800° C., and hydrogen pressure of 6,000 p.s.i.g. coal was rapidly carbonized to char with expulsion of volatiles. Char was then slowly hydrogenated to gaseous hydrocarbons without production of oil.

Jan 1, 1962

By William A. Beck

This report describes the loading and transportation practices employed at the zinc-lead mines of The Eagle-Picher Co., Jo Daviess County, Ill., and Lafayette County, Wis. The report also gives a brief history of the Illinois-Wisconsin zinc-lead district and the operations of the company in the area. The diesel-powered, rubber-tired loading and haulage equipment is described and illustrated from the operational point of view only, and an analysis is made of the materials-handling system without going into health and safety factors. The costs per ton of the various components of mechanical loading, underground haulage, underground crushing, and hoisting for fiscal year 1960 are tabulated.

Jan 1, 1964

By R. J. Matetic, David S. Yantek, David K. Ingram

The National Institute for Occupational Safety and Health (NIOSH) has investigated engineering noise controls to reduce sound levels in cabs on air-rotary drill rigs. A recent investigation revealed that some drillers are exposed to A-weighted sound levels exceeding 85 dB even though a cab is used. NIOSH studied the in-cab sound levels of one such rig. First, preliminary tests were conducted in a controlled environment using accelerometers and microphones with spectral analysis to identify the dominant noise sources for in-cab sound levels. The results indicate that vibration transmitted from multiple hydraulic pumps to the control panel produces a dominant spike in the sound level spectrum in the 400 Hz 1/3-octave band. Next, field tests were performed in a production environment to evaluate noise controls to reduce in-cab sound levels. It was found that utilizing hydraulic noise suppressors reduces the structure-borne noise transmitted to the control panel. Further, using hydraulic noise suppressors and enhancing soundproofing reduced the in-cab A-weighted sound levels by as much as 4 dB.

By Sara Jane Boles

In recent years the interest in rare-earth compounds as refractory materials has exceeded the available literature on the subject. While some basic properties, such as density and melting point, of the more readily available rare-earth compounds have been reported in the literature, relatively few papers can be found that deal comprehensively and primarily with high-temperature refractory properties and applications of rare-earth oxides, carbides, sulfides, and nitrides. Therefore, this bibliography has been pre-pared for the use of the ceramic industry as a guide for locating and utilizing the scattered and frequently fragmentary information available. The term "rare earths", as applied in the literature search for this bibliography, is understood to include the following elements: cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanum, lutetium, neodymium, praseodymium, samarium, terbium, thorium, thulium, uranium, and ytterbium. (On the periodic chart, these elements appear as numbers 57 through 60, 62 through 71, 90, and 92.) It is emphasized that many of the abstracts included are from papers in which the rare-earth compound or compounds are treated along with several other ceramic materials, are mentioned only secondarily, with primary interest placed on a more commonly used refractory material, or are used as part of a mixture of materials formed experimentally and reported on in the paper. As the better known rare-earth materials, such as the oxides of uranium, thorium, and cerium, appear more frequently in the literature, they also appear more frequently in this collection. Articles abstracted include only information on the basic properties that are of interest to the refractories investigator. References to crystal lattices and related topics are generally excluded from this publication. The temperature 1,500° C. has been set arbitrarily as the lower limit for reported data on thermal properties. However, because of the scarcity of information, some reports are included in which data are limited to those obtained at lower temperatures. Many of the articles abstracted include lists of references that will be of additional assistance in pursuing specific lines of investigation.

Jan 1, 1962

The Bureau of Mines annually publishes statistical data reflecting technological trends in the minerals industry (metals and nonmetals except fuels). This report outlines recent developments and trends and the technology outlook for mining practices and metallurgical processing based on a review of the minerals industry during the past 2 years. A historical statistical series which indicates trends in the minerals industry has been extended with 1970 data. In addition, data are given from a 5-year Bureau of Mines cyclic canvass of froth flotation plants. Data for 1970 are compared with those of 1960 and 1965.

Jan 1, 1972

By R. H. Fernald

In 1900, as far as available records show, there were only two producer-gas power installations in the United States. In June, 1915, the number probably exceeded 1,000. Of this number, some 84.5 per cent comprised small plants using anthracite, and only about 15 per cent of the total number utilized bituminous coal and lignite. In addition to these, two plants used wood, and three or four used oil. In the main, however, the larger sized units are operating on bituminous coal and lignite.

Jan 1, 1916

By C. Özgen Karacan

Gob gas ventholes (GGV) are used to control methane inflows into a longwall operation by capturing it within the overlying fractured strata before it enters the work environment. Thus, it is important to understand the effects of various factors, such as drilling parameters, location of borehole, applied vacuum by exhausters and mining/panel parameters in order to be able to evaluate the performance of GGVs and to predict their effectiveness in controlling methane emissions. However, a practical model for this purpose currently does not exist. In this paper, we analyzed the total gas flow rates and methane percentages from 10 GGVs located on three adjacent panels operated in Pittsburgh coalbed in Southwestern Pennsylvania section of Northern Appalachian basin. The ventholes were drilled from different surface elevations and were located at varying distances from the start-up ends of the panels and from the tailgate entries. Exhauster pressures, casing diameters, location of longwall face and mining rates and production data were also recorded. These data were incorporated into a multilayer-perceptron (MLP) type artificial neural network (ANN) to model venthole production. The results showed that the two-hidden layer model predicted total production and the methane content of the GGVs with more than 90% accuracy. The ANN model was further used to conduct sensitivity analyses about the mean of the input variables to determine the effect of each input variable on the predicted production performance of GGVs.

Jan 1, 2009

By M. J. Senk, A. Lusin

Federal regulations require that methane liberated at the face be diluted and removed to maintain methane gas concentrations below 1 pct (CFR) in working places and intake air courses. The delivery and distribution of intake air at the face is critical for effective face ventilation. Improved techniques for monitoring the movement of intake air to the face are needed. A test system was developed and a computer program written for using a three-axis ultrasonic anemometer to measure airflow in a simulated mine entry. Results of tests conducted in the entry showed that the anemometer is a valuable tool for measuring mine airflow conditions near the face.

By C. F. McCarroll

The effectiveness of an industry's safety activities can be gaged best by the accident records of that industry. In an effort to gage conditions in the petroleum industry, and with the objective of helping to reduce the number of accidents in it, the Bureau of Mines from time to time has tabulated, analyzed, and published pertinent statistical information.3/. These reports have dealt with distribution, causes, and costs and related phases of accidents for various and collective divisions of the petroleum industry in several sections of the country. This type of study aids the personnel of the Bureau in planning the course of its activities in accident-prevention work and gives useful data to persons engaged or interested in the promotion of safety in the petroleum industry, which will aid them in their efforts to reduce the number and severity of accidents. A majority of petroleum operators and "service? contractors have acknowledged their responsibility to provide their employees with safe working conditions and to their stockholders for greater economic value of invested capital by establishing safety divisions within their respective organizations. Such divisions have a primary duty, namely, to see that properly designed and guarded machinery and working equipment are furnished the employees and that they are trained in the safest practical methods of performing their work. Some companies and individual operators, however, have shown little or

Jan 1, 1939

By L. V. Clark, Arthur La Motte

"INTRODUCTION The U. S. Bureau of Mines in 1930 and 1931 made a study of the properties and characteristics of liquid-oxygen explosives (L.O.X.) at the request of one of the largest users, in order to determine and eliminate the hazards attending its use.This report deals with the examination of absorbents for L.O.X. to (1) determine their most desirable and most undesirable characteristics, (2) to find ways and means of desensitizing absorbents to mechanical shock, and (3) to determine the effect that such desensitization of absorbents has on the explosive Characteristics of L.O.X.ABSORBENT MATERIALS The absorbent used in driving the Simplon Tunnel, the earliest project in which L.O.X. was used, was composed of crude petroleum, soot, and kieselguhr. During the World War, powdered cork, soot, sawdust, powdered straw, or other similar powdered materials were mentioned in the German military instructions for use of ""liquid air"" explosives. At that time the common types of absorbent, materials were compounded ones containing the above ingredients as well as kieselguhr, paraffin, gas oils, charcoal, bituminous coal, etc.Kuryla and Clevenger4 investigated absorbents of the above type and made the following statement concerning them:"

Apr 1, 1932

This publication is the fourth in a series of miners? circulars covering various phases of accident prevention in bituminous-coal mines; these circulars constitute a text hook for courses of instruction on accident prevention in bituminous-coal minim. To these may be added material of particular interest in the field where the course is presented. Other circulars in the series are: Accident Statistics as an Aid to Prevention of Accidents in Bituminous-Coal Mines (Miners? Circular 47). Accidents from Falls of Roof and Coal in Bituminous-Coal Mines (Miners' Circular 48). Accidents from Hoisting and Haulage in Bituminous-Coal Mines (Miners' Circular 49).

Jan 1, 1946

By M. J. Sapko

A moderately scaled apparatus was developed by the Bureau of Mines to determine the fire resistance characteristics of mine conveyor belts and similar type materials. The design of the apparatus was based upon data obtained in full-scale fire tests and features a radiant panel to preheat the belt and a methane-oxygen ribbon burner to ignite the sample under ventilating condi¬tions in a rectangular duct. The test method overcomes the limitations of existing laboratory-scale methods and provides a measure of both ignitability and flammability in quantitative terms. Flame propagation depended upon such variables as air velocity, ignitor heat flux, and belt width and height in the test chamber. Data are presented for nine belt materials and fire resistance ratings are proposed in terms of the flame spread rate, heat release rate, and the critical ignitor heat flux. The ratings discriminate between the fire hazard posed by different fire-resistant belts and tend to be in reasonable agreement with those obtained in full-scale fire tests.

Jan 1, 1981

By B. C. Peterson

Calumet Division, Calumet & Hecla, Inc., whose operations are in Houghton and Keweenaw Counties, Mich., is a highly integrated and complex organization. This division operates mines, a railroad, a concentrating mill, a reverberatory smelter, and the auxiliary generating plants and shops to service these operations. In addition, it operates a sands reclamation plant, leaching plants, a foundry, and a machine shop that serves varied industries with castings and parts for many applications. Calumet & Hecla, Inc. has produced over 60 percent of all the copper that has been produced in Michigan since discovery of the ore in 1864, and in 1959 the company ranked eight among the country's producers with a production of 17,407 tons. To keep abreast of modern accounting systems developed elsewhere in industry and to combat increasing costs due to higher labor and supply costs, as well as increased costs due to deeper mines and lower grade ore, the company has developed a modern machine cost accounting system. This not only provides the usual bookkeeping and cost accounting facilities but offers accurate cost data for engineering evaluation of the mining operation. This system is credited with being instrumental in permitting continued operation of these high-cost mines in a period of increasing costs with no corresponding increase in the price of metal.

Jan 1, 1962

By L. W. Higley

It is estimated that well over 20 million lb of chromium and 8 million lb of nickel, plus other metal values, are diverted annually to furnace dusts, mill scale, and contaminated swarfs in the domestic stainless and other specialty steelmaking industry. Little inroad has been made toward the in-plant recycling of these wastes to reclaim the metal values. The Bureau of Mines has devised a process for recovering about 90 pct of the chromium and molybdenum and well over 90 pct of the nickel and iron from stainless steelmaking furnace dusts, swarf, and mill scale. Other metals such as manganese are also recovered. Initial laboratory results were confirmed and expanded to include a wide variation of stainless steelmaking waste mixtures. Later experiments have included specialty steelmaking wastes other than from stainless steelmaking. Significantly, the ease of technology transfer has been demonstrated by a number of industrial-sized (19-ton) commercial electric furnace heats, in which the pelletized wastes represented some 10 to 20 pct of the furnace charge, replacing part of the normal scrap charge. Results of these successful large-scale trials are presented. Some information is also presented on incorporation into the pellets of chromium-bearing particulate wastes originating from other than steelmaking production. Cost evaluation indicates the process is economically attractive.

Jan 1, 1982

Introduction MINING IS THE BRANCH OF INDUSTRY involving the exploration and removal of minerals from the earth (figure 1). Mining is one of the oldest and most important endeavors of humankind, because it provides the raw ingredients for most of the material world around us and, like agriculture, is the lifeblood of civilization. The main objective of any type of mining is to remove the valuable material economically and safely with minimum damage to the surrounding environment. The Earth has many natural resources on which we depend that must be mined. Coal, oil, gas, and other mineral fuels are used for heating electricity, and numerous industrial processes. Nonfuel minerals such as iron ore, precious metals, and industrial metals, and nonmetallic materials like sodium and potassium are used in chemical and agricultural applications. Even crushed stone used in road building and other construction projects must be mined. Mining affects our standard of living and impacts almost everything we do. A myriad of items that we use in our homes and offices and for transportation, communications, and national defense all require minerals (figure 2). For example, more than 30 different minerals are needed to make a television or telephone! Table 1 lists several commonly mined materials and some of the end uses in our daily lives.

Jan 1, 1995

By M. M. Fine

Research on the solid-fuel reduction of Knob Lake iron or was conducted to upgrade lean and high-grade ores and recover metallized products suitable for ironmaking or steelmaking. The program included bench-scale tests plus a number of continuous campaigns in a 34-inch by 36-foot rotary kiln. In the laboratory, metallizations in excess of 90 percent were achieved by reduction of crushed ore with lignite at 950° C. Subsequent grinding (to minus 200 mesh) and wet magnetic separation yielded concentrates analyzing less than 3.0 percent SiO2 and more than 90 percent Fe. Virtually complete recovery of the iron occurred. During early continuous tests the crushed ore created a serious ringing in the kiln which was solved by balling the fines with bentonite. Unfortunately, at this temperature (950° C) the bentonite militates against the concentratability of the metallized product. For example, a run on direct-shipping ore produced concentrates of 89.5 percent Fe and 4.5 percent SiO2. At 500° C the adverse effect of bentonite disappeared and concentrates of 88.4 Fe and only 2.5 percent SiO2 resulted. However, with comparable feed r Los, the metallization dropped to 73 percent.

Jan 1, 1969

By Ronald F. Balazik

This Bureau of Mines study identifies and examines the costs of Federal, State, and local environmental protection controls on domestic phosphate rock mining, The costs include the expenditures needed to comply with government regulations and the effects that these expenditures and regulations have on supply. The study analyzes costs of environmental impact assessments, air and water quality standards, reclamation laws, potential solid waste controls, and local government restrictions. In addition, an industry survey and the Bureau's Minerals Availability System (MAS) are used to evaluate land management policies that restrict access to phosphate resources, Conclusions drawn from these analyses confirm that (1) domestic phosphate mining has incurred substantial control costs and may be subject to significant new regulatory costs in the next several years, (2) certain environmental controls can discourage mining investment, (3) environmental policies governing land-use controls affect the disposition of sizable phosphate resources, and are key determinants in the development of those resources on the Federal do- main, and (4) environmental costs could diminish the competitiveness of domestic producers.

Jan 1, 1983

By P. G. Guest

Many of the gases and vapors used in anesthesia form explosive mixtures with oxygen or air. Sources of ignition for these mixtures always have existed, in operating and anesthetizing areas. When ether was first introduced, candles and gas-lights and coal stoves caused fires and mild explosions of the vapor-air mixtures. Today the chief causes of ignition are electrical. Fires and explosions are still much too frequent; and, because many of the mixtures are rich in oxygen, the explosions sometimes are very violent. Obvious sources of ignition, such as electric-power sparks and arcs in open motors, switches, and receptacles, as well as exposed incandescent wires and hot plates, usually are recognized by hospital personnel and corrected. A source of ignition that is not so obvious to many is static electricity. Until quite recently the presence of this hazard in a large majority of anesthetizing areas was not even suspected. However, numerous explosions -many of them fatal to patients -have been attributed, with good reason, to sparks from static electricity. In this paper the authors present facts to show the prevalence of static electricity in the average hospital anesthetizing area, and the degree to which this easily developed electrical form of energy constitutes an explosion hazard. An effort is made throughout to explain how static electricity behaves, why it is a hazard, and why certain safety measures are needed and recommended. Following the introduction and a short general discussion of static electricity, which incorporates a glossary of pertinent electrical terms, an account is given of inspections and tests made in a number of hospitals. This account includes many suggestions that should be useful to any person who plans to make similar inspections and tests. However, a comparison of materials and equipment used with those described in the report will reveal, in many cases, the potential dangers and obviate the necessity for tests. The hospital work was supplemented by considerable laboratory research designed to determine the spark energies required to ignite anesthetic-gas mixtures and the exact amount of time involved in developing the usual static charges. The results of this research are reported and the implications examined. The paper concludes with a general discussion of static and related hazards in anesthetizing areas and of the most urgent preventative measures.

Jan 1, 1952

By Oliver Bowles

Sandstone, a widely distributed siliceous sedimentary rock, is the third most popular building stone in the United States. It is formed by the breaking down of preexisting rocks by weathering, subsequent segregation of the detrital quartz grains into discrete deposits by the sorting action of water or wind, and finally cementation of the quartz sand into a coherent rock. The homogeneity and resistance to weathering of the resultant sandstone make it suitable for exterior construction. Its excellent wearing properties explain its popularity for flagging and stair treads. However, quarrying and dressing methods and costs are adversely affected by the abrasiveness and hardness of sandstone especially as compared to limestone.

Jan 1, 1963