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By A. C. Fieldner, W. A. Selvig

Information concerning the fusibility of coal ash has become of considerable value to the consumer of coal, mainly in connection with the troublesome formation of clinker resulting from the melting of the ash constituents of the burning coal. The growing interest in such data has led the Bureau of Mines to make a general survey of the "fusing" or "softening" temperatures of the ash from coals of the United States. It is hoped that this information when used together with the large number of coal analyses published 1 by the bureau will assist the consumer of coal in comparing different coals, and in selecting the coal best adapted for his purpose.

Jan 1, 1922

By Horace C. Porter

Much has been written of the changes undergone by coal in storage and the deterioration of coal through exposure to the weather. In order to obtain definite information for the benefit of the Government departments and of all who store coal in large quantities, a series of tests was begun in the fall of 1909 under the supervision of J. A. Holmes, then chief technologist of the United States Geological Survey, and was continued by the Bureau of Mines after its establishment in 1910. The tests were confined to determinations of the loss in heating value of the coals and did not include a study of other deterioration; for example, in coking quality or the yield of by-products in coking. The Bureau of Yards and Docks of the Navy Department cooperated in tests of New River (W. Va.) coal, a variety largely used by the Navy. A preliminary report presenting a brief account of the early results of these tests has been published by the Bureau of Mines as Technical Paper 16.a The detailed report is presented in this bulletin, which gives a full account of the tests and the analytical data covering a period of five years' storage. Data of somewhat similar experiments for shorter periods with gas coal from the Pittsburgh bed, with Pocahontas coal on the Isthmus of Panama, and with Sheridan, Wyo., subbituminous coal, which is used for railroad and other purposes in the West, are included.

Jan 1, 1917

By Robert Louis Adams

A general discussion of the structure of the junk automobile recycling system shows that the generation of stripped automobile hulks and scrapped automobiles is price inelastic. As a result, it is extremely difficult for the price mechanism to automatically achieve an equilibrium that will prevent the accumulation of excessive automobile wrecker inventories and vehicle abandonment by the last owners of scrapped cars. The new shredder processing technology and the new portable flattener technology have altered the structure of the junk automobile recycling system. The shredder technology has increased the demand for processed automobile scrap. This increased demand is reflected in higher prices paid for hulks by scrap processors. The portable flattener has reduced the transportation cost of shipping hulks to processors. The two new technologies have eliminated, at least potentially, the net cost of shipping stripped hulks so frequently incurred by wreckers in the past. The elimination of this cost eliminates the economic incentive for excessive wrecker inventories. Unfortunately, the incentive for last owners to abandon their cars does not appear to have been eliminated by the new technologies. The last owner of an automobile with no spare parts value is still likely to incur a cost by delivering his automobile to the recycling system. Although a subsidy payment is probably unnecessary to reduce excessive wrecker inventories, such a payment might be one solution to the problem of automobile abandonment. However, there are a wide variety of subsidy programs that could be introduced. Before any Federal subsidy program is introduced to reduce automobile abandonment, it is recommended that the program be tested on a limited basis in many different parts of the country.

Jan 1, 1973

By J. O. Lewis, Carl H. Beal

The material for this paper was collected for the most part by C. H. Beal during the years 1916, 1917, and 1918. Many of the conclusions reached in regard to the life of oil wells have already been published by the Bureau of Mines 1 but those presented in this paper deal particularly with the theoretical aspects of oil production. The report discusses some of the fundamental factors governing oil production, taking up first the conditions affecting the. amount of oil in the oil sand, then those factors that control the rate of production of oil wells, and then discusses several related problems, most of which deal particularly with the effect of the production of one well on that of another.

Jan 1, 1921

By James L. Elder

The Bureau of Mines and the Alabama. Power Co. jointly conducted a first experiment in underground gasification of coal at Gorgas, Ala., during the fall and winter of 1946-47. This preliminary experiment showed that it was not difficult to maintain combustion of coal underground, and that coal in place could be completely gasified. It was noted that the high temperature developed by the gasification of coal in place brought about changes in overlying strata that appeared to be favorable to the process. The high temperatures caused the roof rock to become plastic, to expand, and to settle down on the mine floor directly behind the reacting coke face. These results were promising enough to warrant further investigation of the process. It was believed that if this action could be controlled properly with roofs of similar composition, it would tend to force the gas-making fluids underground against the coal faces. Plans for the second experiment were based in part on this favor-able roof action, and the successful operation of the planned initial straightline passages depended on this fact. Gorgas was chosen as the site for the second experiment for the following reasons: A tract of coal land of sufficient size was available and isolated from the main body of coal; the roof rock was similar in composition to that encountered in the first experiment; and the overlying strata were thick enough to eliminate some of the operating difficulties that had been encountered, In addition, power, water, and machine-shop facilities as well as an adequate supply of labor were available in this area, and the friendly cooperation of the Alabama Power Co. further recommended this site for the planned experiment.

Jan 1, 1951

By Albert H. Fay

This glossary is publi~hed- by the Bureau of Mines as a contribution' to the mining literature in the belief that it will fill a long-felt need. It contains about 20,000 terms; these include both technical and purely local terms related to metal mining, coal mining, quarrying, petroleum, and natural gas, and metallurgical works; names of useful, important, and common minerals and rocks; an<lgeological terms. It presents in one comprehensive volume the available standard, technical terms relating to the mining and mineral industry, as well as provincialisms that have been or are now in use in English-speaking countries. The glossary also includes many terms relating to ceramics and the clay industry, glass making, foundry practice, railway and building construction, electrical installation and power-plant equipment, and chemical terms relating to metallurgical practice. Complete lists of terms for' each of these allied industries are beyond the scope of this glossary. Paleontological terms, although closely associated with geology, are far removed from mining and metallurgical operations, and for this reason have been omitted. In a compilation of this magnitude, it is difficult, within a reasonable time to verify all definitions as to the latest usage. Much verifying was done and it is hoped that the best and latest definitions have been used. Reference to the publications cited will enable the reader to determine approximately the period when the definition was used. Definitions in use by engineers of high national or international reputation are given first preference. When definitions from different sources are the same, credit is given to the earlier author as being the original or nearest to the original source. Immediately following each term the name of the locality wherein the word is presumed to have originated or is widely used is given, where such information is available. The name of the author or source from which the definition was obtained follows the definition, and serves as a key to the publications listed. The terms selected from the various glossaries and publications examined have been compared with the Webster,

Jan 1, 1920

By M. J. Ankeny, J. J. Forbes

"One of the main functions of the U. S. Bureau of Mines, as authorized by Congress, is to investigate safety and health conditions, to disseminate information regarding safe and unsafe practices in mining, and to aid in improving safety and health conditions of mining communities and in promoting the welfare of the miner. Among several methods of reaching the miner and interesting him in safety work, perhaps the most effective is through the 11 mine safety stations and 11 railroad cars known as mine rescue, or more correctly, mine safety cars.Frequently, the Bureau of Mines receives requests for information regarding the purpose, equipment, personnel, and construction of its safety cars used in the field service. It is the intention of this circular to present to the mining public in particular, and to the public in general, some definite information regarding these safety cars and their functions.The cars are operated throughout the mining fields of the United States and are headquartered as follows (see fig. 1): Car 1, Reno, Nev.; Car 2, Raton, N. M.; Car 3, Pittsburgh, Pa.; Car 4, Terre Haute, Ind.; Car 5, Pineville, Ky.; Car 6, Pittsburg, Kans.; Car 7, Huntington, W. Va.; Car 8, Duluth, Minn.; Car 9, Butte, Mont.; Car 10, Des Moines, Iowa; Car 11, Anchorage, Alaska.One of the most important purposes of the U. S. Bureau of Mines safety cars is to render service at mine fires and explosions where human life is endangered. State mine inspectors and other interested persons are supplied with itineraries of the car operating in their districts from time to time, so that they may know at all times where the car can be found in case of emergency. When these disasters occur the car may be reached direct or through its field headquarters, and upon receiving word of a mine disaster, or request for assistance, it immediately proceeds to the scene of trouble. Frequently a special locomotive is supplied by the railroads and in many instances the movement of the car is given the right of way over all other railway traffic. Upon reaching the destination, the facilities and personnel of the car are immediately available for rescue and recovery operations.Following most mine disasters a thorough investigation is made by engineers of the Bureau of Mines, and a confidential report is submitted to the operator. The information gained in this manner from a large number of mine fires and explosions, together with the knowledge gained from the experimental work carried on at the Experimental mine of the bureau at Bruceton, Pa., serves as a basis upon which the bureau is able to recommend preventive measures whereby similar occurrences may be averted. The bureau car is often used as headquarters for the investigating engineer when such an examination is being made."

Mar 1, 1931

By L. C. IlsLey

"The underlying principle of the storage battery was discovered within the memory of many still living, hence storage-battery locomotives, which were made possible by this discovery, represent a still more recent development. The Journal of the Franklin Institute for December, 1883, gives an account of the building of an electrical omnibus by The Electrical Storage Battery Co., of Millwall, London, This, if not the first, was among the first attempts to, use the storage battery as the source of energy for locomotion.During the period 1888 to 1893 occasional attempts were made to apply this idea practically, but not much was achieved along useful lines.. The progress during the next, 15 years was slow, and little success was achieved. Therefore, the last two decades may be considered the successful development period of the storage-battery locomotive.In coal mining, the application of the storage-battery locomotive is chiefly in gathering service in competition with animal or cable-reel locomotives. The locomotive delivers empty cars to the rooms or working places where the coal is being mined and hauls the loaded cars from the rooms. The length of haul depends upon the distance of, the junction point from the active workings of the mine. As a rule the haulage from the junction point to the foot of the shaft or bottom of the slope is done by trolley locomotives, but in some instances where the grades permit this main-line haulage work it: performed by storage-battery locomotives.As the place storage-battery locomotives occupy with respect to safe haulage in gassy mines appears to be misunderstood, it is the purpose of this paper to clarify this point.Those who originally designed storage-battery locomotives had no thought of safety in mind and it is just as well that they did not, as these early types of storage-battery locomotives with open controller open motor, open rheostats, flimsy headlights, and crude wiring were very dangerous electrically and not at' all suitable for use in a gassy mine. These locomotives, however, were placed in mines in which open lights were permitted and they replaced considerable animal haulage. Later they were gradually introduced in mines where closed lights were used, but in most cases these mines were not extremely gassy."

May 1, 1928

By H. K. Kutter

The pressure pulse generated by an underwater spark \vas investigated in relation to its potential use for rock fragmentation. The study established (1) the relation between the peak discharge current and the peak wave pressure; (2) the relationships among the peak wave pressure, the discharge voltage, and the spark gap width; (3) the type and pulse duration of the generated wave; (4) the percentage of energy transmitted in the spark as a function of spark gap width and discharge voltage; and (5) the percentage of energy converted into the pressure wave as a function of gap width and discharge voltage. Spark-generated fractures were studied in two-and three-dimensional rock and plastic specimens. The laboratory results indicated that the pressure pulse generated by an underwater spark is a potential practical tool for rock fragmentation. The paper contains an appendix describing the capacitive pressure gage specially developed for the laboratory tests.

Jan 1, 1969

By Alfred Weiss

These volumes report on the study initiated by the U. S. Bureau of Mines to develop and apply a methodology to quantitatively assess the probability and potential benefits of technological innovation over the next twenty-five years. The potential was recognized for new technology to solve copper industry problems in the United States. Objectives of the study were to: (1) Develop a methodology to obtain the opinions of mineral experts about future events -their likelihood of occurrence, and, conditional on occurrence, when and to what extent they are likely to occur; (2) Identify, select, and describe potential technological innovations which would have significant impact on copper production; (3) Implement the methodology and obtain the opinions of the mineral experts regarding selected copper technologies; and (4) Analyze the expected future benefits of successful technological innovations :n the copper industry. Although individual technologies are continuously examined throughout the copper &apos;community&apos;, this study is the first known comprehensive forecast of future copper technology. This study is also believed to be unique 1n that it represents the consensus opinion of over sixty expert copper technologists on the expected use of innovative technology in the industry over the next 25 years. The report is contained in three volumes.

Jan 1, 1983

By E. B. Nelson, B. W. Gandrud, B. M. Bird

"The Lewisburg No. 2 mine of the Sloss-Sheffield Steel & Iron Company is located in Jefferson County, Alabama, about 7 miles due north of Birmingham. At this point the coal from the Mary Lee seam when coked in by-product ovens yields an excellent quality of metallurgical coke suitable for use in the iron blast furnace; it is also an excellent steam coal. In mining, all three benches are worked. Coarse impurities are largely gobbed by the miners underground.In addition to giving the data obtained from screen-sizing and float-and-sink tests of a representative sample of the raw coal, this report presents the results of slotted-screen tests to show the proportions of flaky particles in selected sizes, and the results of tests to show how much coal is liberated from impurities by crushing the coarsest sizes. These data have been obtained in connection with an extensive study of coal-washing now being conducted by the U. S. Bureau of Mines and the University of Alabama, with U. cooperation of the different operators of Alabama. As the work progresses other reports will follow containing furtner data on the washability both of the Mary Lee seam and of other seams in Alabama and giving the results obtained in preparing these coals by various methods.Although a great amount of investigative work on the preparation of the Mary Lee scam was previously carried on by the various coal companies of the district, comparatively little of this information has been published. In governmental publications three references have been found. Forbes5 gives a number of sections with proximate and ultimate analyses of face samples taken in the mines. Gandrud and Britton'' show sections of this seam at Flat Creek and New Castle; they also give the specific gravity and ash contents of the partings of coal and impurities. In their paper Yancey and Fraser7 include washability studies and washing data from the Sayreton mine of the Republic Iron & Steel Co."

Jun 1, 1930

By R. R. Brandenthaler

A series of open-flow tests was conducted in the Chickasha gas field, Grady County, Oklahoma, during June, 1927, under the direction of the U. S. Bureau of Mines and at the request of the Oklahoma Corporation Commission. The purpose of these teats was to determine whether or not any differences existed in the open-flow volume of a gas well when taken through well-head nipples of different diameters, and further, to establish if possible a relationship between open-flow volumes taken through well-head nipples of various diameters. The open flow of a well is the volume or quantity of gas, measured under standard conditions, that a well will produce when open to the atmosphere. There are several methods used for determining the open flow of wells; some of the methods are more suitable under certain conditions than others. The Pitot tube method is the simplest, is applicable to almost any condition, and is the one most commonly used. In the tests described in this paper no attempt was made to compare the Pitot tube method with the minute pressure measurement method or the orifice measurement method.5

Jan 1, 1928

By Leslie H. Sharp, Martin J. Gavin

Those of the oil-shale operators in this country who are sincerely attempting to make a real industry out of oil-shale developments, are anxious to obtain fundamental data on the retorting of oil-shale; particularly as regards the effect of certain variable factors in the process of retorting on the quantity and quality of products yielded from oil shales when they are subjected to destructive distillation. From careful examination of a con siderable number of suggested processes for treating oil shales and the con flicting ideas on which they are designed, it seems probable that accurate information of a fundamental nature is highly essential to the successful establishment of an oil-shale industry in this country. . Accordingly, the United States Bureau of Mines, in cooperation with the State of Colorado, is undertaking to furnish some definite and impartial information of this type through investigations now under way at the University of Colorado, Boulder, Colo. A retort for the distillation of oil from oil shale has been designed and installed, together with the necessary auxiliary equipment for controlling and determining variable factors of distillation, and for recovering and de termining the quantity and quality of the products yielded from the shales. The retort is of such a nature that conditions of retorting can be accurately . and completely controlled, and varied at will. It is not designed as a com mercial retort, but only for research purposes. A testing laboratory with equipment necessary for the examination of the shales, physically and chemic ally, and the products yielded by them, has also been fitted up . The material used in the investigations is oil shale obtained from the DeBeque, Colorado, shale field. It yields on distillation in the Bureau of Mines testing apparatus, about 42 gallons of oil to the ton, and is there fore a fairly representative sample of the shales that probably will be first worked in Colorado. The shale used will be as uniform as possible in character and oil yield and will all be obtained from the same seam at the same point, in order to avoid the introduction of unnecessary variable factors in the tests and to render results strictly comparable •

Jul 1, 1920

By Oliver Bowles

"Simple systematic accounting that adequately records all transactions has long been regarded as essential to the welfare of any business enterprise. Some of the defects that detract from the prosperity of the slate industry are attributable to a lack of effectiveness in cost keeping. This condition has prompted the United States Bureau of Mines to make a detailed study of accounting methods for the slate industry, and to present for consideration a system of accounts, which it is believed would enable the industry to attain more economical management and operation if accepted by a fair proportion of its important units.The method of accounting presented herein has been worked out with the assistance of leading slate producers and the recommendation are tentative and are submitted in this form as a means of developing constructive criticism. Believing that cooperative effort in this, as in many other problems, will bring the most enduring benefits to the industry as a whole, the writer urges that the most earnest consideration be given to this vital problem now facing the slate industry.Grateful acknowledgment is made of the helpful assistance rendered by R. E. Eckert of the accounting firm of Eckert, Degan, and Palmer of Easton, Pa., in compiling the charts and the explanatory text. He has brought to this work a wide knowledge of accountancy, supplemented by a background of direct contact with the slate industry, and his presence at the various conferences has been of great advantage in clearing up difficulties. The National Slate Association sponsored the cost study and chiefly through the efforts of President W. H. Smith and Secretary W. S. Hays, has aided greatly in conducting it. Acknowledgment is also made of assistance rendered by William F. Marsh of the United States Bureau of Mines."

Nov 1, 1929

By Paul R. Amyotte, Omotayo Kalejaiye, Kenneth L. Cashdollar, Michael J. Pegg

The Siwek 20-L chamber is widely used throughout the world to evaluate the explosibility of dusts. This research evaluated the quality of dust dispersion in the Siwek 20-L chamber using Pittsburgh coal, Gilsonite, and purple K dusts. A Pittsburgh Research Laboratory (PRL) optical dust probe was used to measure optical transmittance through the dust cloud at various locations within the chamber. A total of 540 tests were performed, with triplicate tests at five nominal dust concentrations and six locations. The two standard dispersion nozzles (rebound and perforated annular nozzle) were compared. The transmissions corresponding to the normal ignition delay period were used to: (a) determine variations in spatial uniformity of dispersion obtained with both nozzles; (b) make comparisons between the experimental transmission data and those calculated from theory for the three dusts; and (c) make comparisons with transmission data measured in the PRI, 20-L and Fike 1 -m3 dust explosion chambers. The uniformity of dispersion for the three dusts was similar with both nozzles, despite the differences in nozzle geometry and mode of operation. Transmission data of the three dusts were all significantly lower than those calculated from theory. This was discovered to be, in part, due to significant reduction in particle size that occurred during dispersion. By measuring particle sizes before and after dispersion, values of 60%, 50%, and 20% reduction in particle size (based on the surface weighted mean diameter) were obtained for Pittsburgh coal, Gilsonite, and purple K, respectively. Transmission data from the PRL 20-L, Fike 1 -m3 and the Siwek 20-L chambers indicated comparable results in terms of uniformity of dispersion. However, transmission data from the Siwek 20-L chamber were significantly lower than those of the PRL and Fike chambers. Again, this was attributed, in part, to the significant reduction in particle size that occurred during dispersion in the Siwek chamber. The design of the outlet (dispersion) valve of the Siwek 20-L apparatus charge vessel was largely responsible for the particle break-up. The contribution to particle break-up by the dispersion nozzles and the high level of turbulence in the chamber were found to be minimal. This is a significant finding in that the dust particle size tested for explosibility in the Siwek chamber is considerably smaller than the original dust sample.

By C. W. Vierrether

Tailings from the Pea Ridge iron mine contain significant amounts of apatite, which has rare-earth element values associated with it. In association with the recovery of rare-earth minerals as a secondary resource, the U.S. Bureau of Mines conducted an investigation on the recover ability of the rare-earth minerals from these tailings. The mill tailings were subjected to a phosphate flotation to separate the apatite from other constituents. More than 70-pct recovery of the rare-earth values was achieved. Based on mineralogical characterization and prior analysis of rare-earth-bearing breccia pipe material at Pea Ridge, it is proposed that processing this phosphate concentrate on a vanner table would yield up to a 95-pct recovery of the rare earths in the concentrate, with the apatite reporting to the tailings. Intensive ore microscopy studies of the original tailings to the flotation products led to the identification of monazite, xenotime, and rare-earth-enriched apatite as the major rare-earth-bearing minerals in the tailings.

Jan 1, 2010

By John C. Machisak

The National Safety Competition is sponsored and conducted annually by the Bureau of Mines, U. S. Department of the Interior, to stimulate greater interest in safety in the mineral-extractive industries and to encourage the development of more effective accident-prevention programs. Since its beginning in 1925, thirty-four safety contests have been conducted. This publication reports results of the 11 annual contests for the period 1948-1958, inclusive. Mineral operations awarded the "Sentinels of Safety" trophy for the best safety record in their competitive group as well as those ranking second, third, fourth, and fifth are listed along with a summary of their achievements in preventing disabling injuries. In addition, this publication contains statistical information reflecting the disabling work-injury experience of all other mines and quarries enrolled in the annual contests. The injury statistics of these operations are arranged in the six groups of the competition and through 1955 are the only data on injury-severity at noncoal mineral operations published by the Bureau of Hines. Recognition of the National Safety Competition in promoting safety has increased steadily during its 34 years. The number of plants participating in these annual competitions increased from 210 in 1925, its first year, to a record of 675 in 1958. The expanding scope of the National Safety Competition indicates that more mines and quarries in the United States are enrolling 90 all available means to promote safety on the job will be used. Safety contests like this are generally recognized, in the field of safety promotion, as an effective way to arouse and hold the interest of employees and officials in accident-prevention programs. They tend to forge individual precautionary acts into group action centered on a common objective, such as winning the ?Sentinels of Safety? trophy.

Jan 1, 1960

By Michael J. Sapko, Kenneth L. Cashdollar

In This Chapter [Methane ignition as initiation source for much larger secondary coal dust explosions Rock dusting requirements to prevent coal dust explosions Dangers of hybrid mixtures of methane and coal dust] Although methane explosions are dangerous, those that involve coal dust are even more so. If exploding methane disperses and ignites the coal dust that has accumulated on the mine ribs and floor, the burning coal dust immeasurably increases the strength of the explosion. Such methane-dust explosions are prevented by inerting the coal dust in a way that prevents the exploding methane from igniting it. This chapter discusses the dust hazard and how it is pre-vented in U.S. coal mines. METHANE IGNITION AS INITIATION SOURCE FOR MUCH LARGER SECONDARY COAL DUST EXPLOSIONS The typical scenario for coal mine explosions starts with the ignition of a flammable methane-air atmosphere near the face. The turbulent winds from the primary methane explosion then disperse the coal dust. If there is insufficient rock dust (usually limestone), a secondary coal dust explosion then propagates throughout large sections of the mine. These scenarios have been studied extensively at the Bruceton Experimental Mine (BEM) and the Lake Lynn Experimental Mine (LLEM) of the NIOSH Pittsburgh Research Laboratory. The minimum quantity of methane required to initiate a coal dust explosion was studied in 1930 in the BEM [Rice et al. 1933; Nagy 1981] and then later in the LLEM, whose cross-sectional area (130 ft2) is over twice that of the BEM [Sapko et al. 1987a]. Studies conducted in the BEM closely simulated conditions that existed in operating mines in the early 20th century. The later tests in the 20-ft-wide entries of the LLEM simulated the geometries of modern mines with advanced roof support technology. The data from the BEM tests show that 13 ft3 was the minimum quantity of methane at the face that, when ignited, would disperse and ignite coal dust. In the BEM, this amount of methane was mixed with air to form a total flammable volume of about 140 ft3 of a 9% methane-in-air mix-ture. In the wider entries of the LLEM, about 37 ft3 of methane was required to disperse pure coal dust and start a self-sustained coal dust explosion. This amount of methane was mixed with

Jan 6, 2006

By John R. Bradley

The object of this paper is to survey and analyze the bearing of economic nationalism, competitive sources of energy, and technologic developments on international trade in coal with especial reference to the competitive position of the leading coal-exporting countries in the Italian market, the largest in the Mediterranean region, and the Brazilian market, the second largest in Latin America. The political, economic, and financial disturbances caused mainly by the World War have resulted in an amazing situation. Especially since 1930 have conditions been complicated.

Jan 1, 1936

By A. Wahib Khair

"This article first describes the impact of respirable dust on the health of miners in underground coal mines in the United States of America. Second, it identifies the major sources of dust generation, namely cutting tools in the road headings. Two surveys associated with cutting tools were made to determine the useful life of these cutting tools, and to determine the effect of cutting tool wear on productivity of the continuous miners. Third, this article presents the results of a series of experiments carried out in the Rock Mechanics Laboratories at West Virginia University in order to study: 3.1 the effect of cutting tool rate of wear on respirable dust generation, 3.1.1 the effects of rock materials on tool wear and respirable dust generation, 3.1.2 the effect of cutting tool geometric parameters on respirable dust generation, and 3.1.3 the effect of tip materials used in the cutting tool on respirable dust generation. Recommendations in regard to cutting tool design are also presented in this paper.Silica and coal dust are the two major elements affecting the health of underground miners. According to Lemen [1] approximately 1,500 men died due to breathing in silica dust in 1936 while tunneling through a mountain of mostly silica, near the town of Gauley Bridge, West Virginia. Coal dust resulting in lung diseases in one of the major health hazards in underground coal mines. The impact of black lung on miners, coal workers' pneumoconioisis (CWP), has ranged from 16,000 to 23,000 each year since 1982 [1].The trend for conventional mining to continuous machine cutting of coal, using more productive machinery, is inexorable. Intolerable level of dust generated at the face is an indication of inefficient coal/rock cutting by these machines. The federal goverment of the United States paid about 11.7 billion dollars in workmen's compensation to more than 470,000 miners with CWP [2]. Bieniawski and Zipf [3] reported that annual benefit payments were about 2 billion dollars. The enactment of the Health and Safety Act in 1969 in the United States triggered the initial investigation into coal cutting mechanisms and cutting tool designs.The surveys concerning the utilization of cutting bits and performance of continuous miners in underground coal mines were made in order to have first hand information about bit consumption and coal produ¬ction.Three types of used bits, commonly utilized cutting tools on continuous miners, were collected from different coal mines. The used bits were grouped into symmetrically and asymmetrically worn bits. Distribution analysis for weight loss and conical height loss was done. Details of the results are presented elsewhere [4], here the results are summarized briefly. The analysis shows that approximately 50% of the collected bits have worn asymmetrically, which shows that many bits do not rotate properly during cutting. Analysis of the distribution of bit wear showed that the degree of bit wear varied from one type to another and with mining conditions. On average, the weight loss of the used bits was 4% to 7% with a maximum of 31%. Correspondingly, the loss of the conical height was observed to vary between 11% and 23% with a maximum of 71%. Figure 1 shows typical data associated with some of the used bits."

Jan 1, 1998