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By Vladimir Adamek

This paper describes the Bureau of Mines development of a novel subsidence prediction methodology suitable to the mining and geologic conditions in the Northern Appalachian Coal Region. It describes the computation of vertical and horizontal movements, inclination, curvature, and horizontal strains. The substance of this method is the separation of the effects of lithology by introducing a correlation between hypothetically homogeneous overburden and existing lithologic conditions, while providing for different mining conditions, i.e., underground geometry and overburden thickness. The effects of lithology have been expressed in the form of a variable subsidence coefficient within the subsidence trough. The subsidence coefficient is considered a constant for other predictive methods. Field data from 16 test sites at 11 Bureau longwall panel studies were used in the analysis. For each panel, the characteristics of the variability of the subsidence coefficient were defined. Regression analysis of the subsidence coefficients from all test sites on their locations relative to the edges of their respective panels yielded a third-degree polynomial equation. The results from additional longwall panel studies, not included in the regression analysis, were used to prove the validity of this method. To facilitate the use of this precalculation methodology, a computer program was written in BASIC for use on a personal computer.

Jan 1, 1987

By J. R. Wait, D. A. Hill

The feasibility of locating a buried vertical magnetic dipole source (horizontal loop) from surface measurements of the vertical and horizontal magnetic field components has been investigated by Wait (1971). , For sufficiently low frequencies, the magnetic fields have a simple static-like behavior, and a single observation of the ratio and relative phases of the vertical and horizontal field components is sufficient for location when the earth is homogeneous. However, when inhomogenieties are present, the surface fields will be modified, and source location may be more difficult. In order to obtain a quantitative idea of the surface field modifications, we consider a spherical conducting zone as a perturbation to the homo- geneous half-space. A rigorous solution for the buried sphere problem has been formulated by D'Yakanov (1959). Unfortunately, his solution is restricted to azimuthally symmetric excitation, and even then the solution is not in a convenient computational form. However, if the sphere is electrically small and is located at a sufficient distance from both the dipole source and the interface, the scattered fields can be identified as the secondary fields of induced dipole moments. The latter are equal to the product of the incident fields and the polarizabilities of the sphere. The details of the approach are given by Hill and Wait (1973). Wait (1968) has used this induced dipole moment approach for scattering by a small sphere above a conducting half-space. The method has the advantage that it is easily generalized to scatterers of other shapes for which both the electric and magnetic polarizabilities are known, such as spheroids (Van de Hulst, 1957). This concept has

Jan 1, 1973

By H. H. Fukubayashi

This Bureau of Mines report describes the development of a pyrometallurgical process for the recovery of the zinc and lead contained in brass smelter flue dusts, which constitute a recycling or disposal problem. Tests on brass flue dust from several sources were made in a quartz tube, heated by an electric furnace to temperatures as high as 1,050° C. The dusts were mixed with carbon and heated in an oxygen-free atmosphere. It was demonstrated that 98 pct of the zinc and 12 to 25 pct of the lead, both in the metallic state, could readily be removed from the dusts. It was also found that 75 pct of the zinc could be recovered, with less than 0.1 pct of the lead, in the absence of chlorides. Pelletization techniques were investigated and 0.6 inch pellets were found to be optimal. Pelletizing results in a tenfold reduction in volume.

Jan 1, 1974

By C. Sunderman, J. Johnson, S. Signer

Researchers at the National Institute for Occupational Safety and Health have developed a miniature data acquisition system (MIDAS) that can measure resistance changes and temperature, store data for later retrieval, and illuminate LED lights. This instrument can be used with strain-gaged bolts, cable bolts, CSIRO stress-measuring gages, string pots, and any other instrument that uses single-ended, resistance-type gages. MIDAS has the capability to measure up to 16 gages at preset time intervals and store more than 2000 scans, yet is small enough to fit in a 35-mm hole. Because the MIDAS consumes little power, a 9-V alkaline battery will operate the system for 6 months. Data from the MIDAS can be sent to a PC via an RS232/RS485/IRdA port. A software program was written to set operation parameters, graph data, and store all information directly to a spreadsheet. Three LED lights change from green to yellow then red based on reading levels and/or rates of change. This feature can be used with different types of gages to warn miners of possible rock instabilities. The MIDAS has received MSHA experimental permissibility approval and is currently being tested at several mines.

By R. V. Ramani, V. T. Burgos, J. A. McClay

The data for Test I1 describes an underground bituminous coal mine operating in a 72 inch seam, with an estimated production rate of 4,257,000 tons per year. The system includes 15 continuous mining sections, conveyor belt haulage, and a rail network for supply and personnel transportation. The following section includes the input data sequence, annual cost report, and cash flow analysis "report for this data set.

Jan 1, 1975

By R. E. Head, Virgil Miller

"Under existing conditions in the treatment of oxidized lead ores containing small quantities of molybdenum no provision is made for the recovery of the molybdenum. Considerable quantities of this important element are lost in the slags of the lead smelters and constitute an economic waste. There is little or no probability that slag dumps containing molybdenum in small quantities could be economically treated for the recovery of the element, and steps for the prevention of waste in this respect must be taken prior to smelter treatment.Wulfenite, lead molybdate (PbMo04), and molybdite, molybdic ocher (Mo03), are the molybdenum minerals most abundantly found in deposits of oxidized lead ores. Wulfenite contains 39.3 per cent molybdenum trioxide and 60.7 per cent lead oxide; molybdite contains 66.7 per cent molybdenum and 33.3 per cent oxygen. Plumbojarosite, argentojarosite, cerussite, and occasionally anglesite are commonly associated with wulfenite ores, and the oxidized iron content is usually fairly high.The recent discovery and development of a body of wulfenite ore in the Star district near Milford led to a cursory microscopic examination of samples of the ore, followed by a few preliminary tests which had for their object the separation and recovery of the lead and molybdenum in separate products.The microscopic examination showed that the samples used in the work were composed of wulfenite, plumbojarosite, and a small quantity of cerussite, and indicated that the iron content was quite high. The ore was porous and yellowish-brown; crystals of wulfenite appeared to be quite uniformly distributed through it, and this mineral and plumbojarosite (Pb0.3Fe203.4S03.6H20) apparently accounted for the major part of the lead content, although lead"

Sep 1, 1928

By R. V. Ramani, V. T. Burgos, J. A. McClay

Cost Systems Cost systems are organized methods of collecting, allocating, and accumulating resource utility expressed in terms of money. There are two major spheres of cost accumulation: financial accounting and cost accounting. Financial accounting deals primarily with historical costs and provides a means of measuring and recording cost events which have al¬ready taken place. While there are no legal requirements to control the methods of recording and reporting cost data in the United States, the procedures in use are guided by professional organizations such as the American Institute of Certified Public Accountants. The final pro¬ducts of financial accounting practices are the income statement and balance sheet which describe the financial status of the organization under study. Cost or managerial accounting is an expansion of financial ac¬counting procedures, providing more detailed cost breakdowns on present operations with one objective being the projection of present costs into the future. The projection process tends to limit the accuracy of the information; however, to management and project justification per¬sonnel, data on future operations tends to be of greater value. The basic principle behind cost accounting is the cost cycle. As products are developed from raw materials, the value of the work-in¬process increases due to the cost input of the various fabricating ele¬ments. Thus, from the basic input elements of facilities, labor, and raw materials, costs are added to each unit of production as a function of the work performed on that unit.

Jan 1, 1975

By Robert L. Chufo

The paper, "An Electromagnetic Roof and Rib Thickness Sensor" presented at The 12th WVU International Mining Electrotechnology Conference in 1992, presented the results of roof coal thickness measurements in underground mines and rib coal thickness measurements in highwall mines. The microwave sensor described uses a unique spatial modulation scheme created by antenna motion, along with frequency domain signal processing, to solve the problem of media, target, and antenna dispersion. This paper further describes the advantages of the unique frequency domain signal processing technology chosen by the U.S. Bureau of Mines in extending previously reported one-dimensional thickness measurement technology to the generation of a full three-dimensional underground image of the underground environment. The electromagnetic signature of a media, whether it is coal or other geological material, is its permeability and permittivity and the effect on the velocity and amplitude of an electromagnetic wave as it passes through. High-quality imaging cannot occur without the identification of, and correction for, the permittivity and permeability of each layer of a multilayer geological deposit. Clutter, or any signal that can interfere with target discrimination, usually comes from objects in the field of view for which there is no design control. These are nuisance targets with possibly very high contrasts compared to the real target. The only proven tool to reduce clutter is to increase spatial, spectral, and polarization diversity. This paper will describe some techniques being used by the U.S. Bureau of Mines to increase the information content of both single-dimensional and three-dimensional imaging systems through the identification of media distortion mechanisms made possible by the use of spatial/spectral sensor technology. These techniques will permit high quality imaging in an environment where the data is corrupted by dispersion and clutter.

By A. B. Hooler

"A complete list of permissible mine equipment, tested and approved by the Bureau of Mines previous to January 1, 1947, was published as Information Circular 7432. 3/The present list is a supplement thereto that includes all of the equipment approved during the calendar year 1947.The items are numbered to indicate the consecutive order in which each type of machine or device was approved in its particular classification. Thus, Information Circular 7432 showed six air compressors on the active list; two additional compressors, Nos. 7 and 8 in this category, were approved during 1947.Items 2 and 7, unmounted loader and power unit, respectively, under Loading and Conveying Equipment, item 2, rubber-mounted mining machine and item 8, distribution box, appear in Information Circular 7432. They are repeated to show that approvals of these four equipments were extended to cover an additional voltage rating which requires material change in design.Equipment listed in these circulars is approved by the Bureau of Mines only when found upon inspection and test to comply with minimum standards of safety as outlined in schedules prepared on the basis of many years of experience in dealing with safety problems of the coal-mining industry. The use of such equipment in mines known to be gassy, as well as in those that may become so, is earnestly recommended in the interests of safety. This circular is published so that the industry may be kept informed as to the many types of machines, devices, and lamps that are available for reducing explosion and other hazards incidental to coal mining. The present paper, with Information Circular 7432, gives the complete list of permissible mine equipment that is available under the various classifications."

May 1, 1948

By John N. Murphy

INTRODUCTION It's a pleasure to be with you and to share in this opening session for the 27th Annual Institute on Mining Health, Safety, and Research. As we come together today, I would like to reflect for just a moment on the past Institutes. Much of the progress in Mine Health and Safety has been the subject of presentations and discussions at the previous Institutes, either by identifying the issues, proposing techniques to overcome the problems, or presenting new findings to address important issues for the mining industry. May I extend our thanks and congratulations to VPI and to the planners and organizers of all of these Institutes for their important contributions to our mutual goals of improving mine health and safety. In the time available today, I would like to accomplish two objectives: 1. Provide my assessment of the current status of the Mining Health and Safety Research Program; and 2. Share with you the continuing need and direction for the Mining Health and Safety Research. MINE HEALTH AND SAFETY RESEARCH TODAY Mine Health and Safety Research was conducted formerly at four geographical locations within the USBM, specifically: Pittsburgh, Spokane, Twin Cities, and Denver. Although the Twin Cities and Denver Centers were closed, we have been successful in relocatingfmaintaining much of the core competencies to conduct a responsive, multidisciplinary Mine Health and Safety Research Program. The current staff at Pittsburgh and Spokane directed toward Health and Safety Research totals 397. This includes Lake Lynn Laboratory, about 60 miles southeast of Pittsburgh, where large-scale mine fire and explosion research is conducted. With the closures and transition we have worked to maintain the core competencies necessary to address Health and Safety issues. In some cases we have made arrangements to provide the requisite core competencies through external organizations. An example is the reassignment of the diesel particulate instrumentation capability from Twin Cities to Pittsburgh. In the case of diesel emission control, due to the cost of relocating laboratories and the lack of the appropriate skills at Pittsburgh or Spokane, the emission control laboratory is now being operated in Minneapolis through a contractual arrangement with the University of Minnesota.

By D. Harringtong

"There has been much writing and argument on the subject of giving bonuses to miners, quarrymen, metallurgical and chemical workers, and others as a stimulus for safe work and for work safely done. Theoretically, everyone should be careful and should not need monetary or any other type of encouragement for the prevention of accidents; as a. fact, few people are careful, and this is primarily the reason way many if not most accidents occur. A bonus, however, is not simply money given away by an employer; it must be earned, so to speak, before it becomes due; in other words, if the standard established is not reached, no bonus is paid, and in many cases some disciplinary action is taken.The United States Bureau of Mines Is asked from time to time for suggestions for rewards to mine workers who have a good attitude toward working safely or who need some stimulus to cause them to make greater or more earnest efforts toward safety for themselves and their co-workers. A recent inquiry prompted the collection of data on some safety bonus systems from reports of this bureau's field engineers and others, and some of these Now given. Bonus practice at both coal and metal mines is included because a system used at metal mines is generally adaptable to coal mines; in fact, in numerous cases, bonus systems recently started at some coal mines are based on systems in vogue and giving satisfaction some metal mines; in-some instances, also, metal mines have been able to get good suggestions from coal mines or from the cement or petroleum industries. it .should be understood that a bonus, even as applied to the encouragement of safety, does not necessarily mean payment of money; in fact, some successful bonus systems have in them no direct money exchange; hence, the bonus as treated in this paper is that defined as ""Something given in addition to what is ordinarily received by, or strictly due to, the recipient.""Acknowledgment is given here to members of the safety division of the Bureau of Mines who sent in some of the information here presented; to the Engineering and Mining Journal and Mining Congress Journal, from which some items were abstracted; to various mining officials who gave data in one form or another; and to M. von Bernewitz, of the United. States Bureau of lines who aided in framing parts of this paper."

Jun 1, 1932

By Ronald S. Conti

This paper describes technology and training that has been identified for underground emergency responders. Historically, underground mine rescue teams have only received training in the course of actual emergencies, or in simulated mine environments, usually on the surface, with placards to identify objects and hazards. Also, while U.S. Federal Regulations require all underground miners to walk escapeways and conduct fie drills every 90 days in a smoke-free environment, this does not fully prepare them for the conditions that will be encountered in real escape situations. Therefore, it is extremely important that miners are provided with adequate technology and that training simulations are conducted in a realistic manner. A series of mine rescue training and mine emergency response development (MERD) exercises, and in-mine smoke training was developed, conducted, and evaluated by state and company teams, and by National Institute For Occupational Safety and Health (NIOSH) personnel. The training exercises were held at NIOSH's Lake Lynn Laboratory (LLL) and operating mines during the past several years. This training resulted in improved technology and training for mine rescue teams, fire brigades, first responders, and miners in general. For example, existing technologies were identified to help responders during exploration and recovery operations. These included various chemical light shapes, strobe lights, light vests, and laser pointers to identify team members. Most of these devices may be used to mark underground areas and certain mine materials. Strobe lights were used for mapping out escapeways and lasers were used to negotiate travel through smoke. Thermal imaging systems allow rescue personnel to see in darkness and through dense smoke, and allows the user to easily locate missing or trapped personnel and heated areas. A hands-free communication system showed potential for enhanced communications between team members, the fresh air base, and command center. A new team lighted-lifeline allows for flexibility in movements of team members during routine tasks and allows them to easily find their fixed position on the lifeline. Of all the technology evaluated by underground personnel, laser lights and lifelines were most beneficial in leading personnel to safety and out of the mine in smoke-filled passageways. A positive-pressure inflatable escape device (IED)/airlock, was used to isolate the "hazardous" environment from fresh air and allow rescue team members to traverse through. An inflatable feed- tube partition that can rapidly block large openings such as underground passageways or tunnels and simultaneously provide a feed-tube for high-expansion foam generators was also deployed during the simulations. These technological advancements have improved the state of readiness for rescue personnel and have increased the chances of survival for all personnel escaping from underground emergencies.

By C. A. Herbert

"Haulage accidents usually are responsible for about 17 or 18 percent of all coal-mine fatalities and about 21 percent of all non-fatal coal-mine accidents. When the relatively small number of employees continuously exposed to haulage hazards is considered, it would appear that haulage is more hazardous than any other phase of coal-mine operation.Haulage accidents have increased from year to year, doubtless due to the increase in electrical haulage, and particularly to the use of larger cars, heavier locomotives, longer hauls, and greater speed. Unless very definite steps are taken to eliminate the causes of these accidents, they will continue to increase rather than be reduced, as they can and should be.Underground haulage in many of the large modern mines of today is similar in many respects to railroad practice. In recent years the railroads have made wonderful strides in reducing accidents, and instead. of being one of the most hazardous occupations, as it once was, railroading is now one of the safest. Doubtless, if thought and action, similar to that given to reducing accidents among railroad passengers and employees, were given to safety in mine haulage, under¬ground haulage accidents could be reduced in about the same ratio.Haulage accidents may be classified, according to responsibility, into two groups - those for which management is largely responsible and those for which the employee is largely to blame; there is, however, an overlapping of responsibility from one group to the other. If, therefore, haulage accidents are to be reduced, it is absolutely essential that both management and employees cooperate to this end.In the first group, for which management is largely responsible, may be included accidents due to faulty equipment, moor track, a poorly arranged system of haulage, lack of clearance or of overhead protection, and dirty roadways; even in these features, however, the employee is not without a measure of responsibility, as failure of haulage equipment possibly may be due to lack of care on his part, failure to report when equipment is out of order, or failure to do a good workmanlike job of installing or repairing or operating.To the second group of accidents for which the employee may be largely responsible, belong those caused by such careless practices as jumping on and off fast-moving trips, coupling on the ""fly"", running at excessive speeds, failure to properly block cars, and similar hazardous and unnecessary acts of omission or commission. If, however, management condones such practices, or, as in some instances, insists upon them, it must accept its share of responsibility for the accidents that inevitably result.Some of the most prolific sources of haulage accidents will be discussed briefly, together with the steps that may be taken to minimize their occurrence."

Oct 1, 1939

By Steven J. Page

Overexposure to airborne respirable crystalline silica dust can cause disabling or fatal respiratory disease, and mine worker exposure to silica dust continues to be an ongoing occupational health concern. Exposures of surface coal mine rock drillers to respirable crystalline silica are of particular concern. On surface coal mine drills, bailing air flushes the cuttings out of the drill hole. Conveyor belting material is typically used to fabricate a shroud around the drill deck in an effort to contain the drill dust so that it can be captured by a collector. Dust leakage from the drill shroud is usually the worst dust source problem on most drills. The focus of this work is drill shroud dust leakage and the relationships of various drill parameters on this leakage. Experimental data were obtained and used in combination with dimensional analysis to establish these relationships. In general, it is found that airborne respirable dust (ARD) concentrations vary in a direct relationship with shroud leakage area and in an inverse relationship with drill deck cross sectional area and shroud height. This work expands the testing and dimensional analysis previously reported for collector/bailing air flow ratios ranging from 2:1 to 4:1 to include ratios approaching 1:1. A semi empirical mathematical model has been developed and expanded to describe ARD generation on surface coal mine drills. Geometric parameters included are drill deck height and cross sectional area, shroud leakage associated with the deck shroud, and the operational parameters of bailing airflow and dust collector airflow. The relationships can be described by logarithmic functions and yield predictive ARD values, which fall in the range measured on operating drills for collector/bailing air flow ratios greater than 2. However, at values of collector/bailing air flow ratios of approximately 1.1, the amount of ARD shows minimal response, if any, to drill deck shroud improvements that do not result in near perfect seals. This is a condition that can occur in actual operation and is a substantially different result than previously expected and reported. Application of these results should provide mine operators with sufficient information to determine (1) the relative magnitude of their dust emissions, (2) where they should focus their efforts to reduce ARD emissions and (3) the improvement they could reasonably expect to achieve. Given that exposures of surface coal mine rock drillers to respirable crystalline silica are of particular concern, substantial reductions of airborne silica dust during drilling may be estimated and achieved through use of the analysis presented. Keywords: drill; dust; model; dimensional analysis

Jan 1, 2008

By L. C. Ilaley

The Buresa. ot Mines at its Pittsburgh Station conducted tests aa earl7 a.a 1911 looking into the satety of miniature electric bulba. The first teata were maie with bulbs euch as were being sold with the partly developed lamps then on the market. 'l'he.sa aarly teats demonstrated the da.nger of using minia.tu:re bulbs in explosive mine atmospheres unless the current that enet gized the glow!ng filament was in aome minner inter.N.ptecl if the glass surrounding the filanant should be broken.

Jun 1, 1922

GLOSSARY Acid- and toxic-forming materials. Rock or coal layers containing significant amounts of pyrite or other minerals which, if exposed by coal mining, will cause acid or toxic drainage to occur when acted upon by air and water. Add mine drainage. Any water with a pH less s than 6.0 draining from a coal mine. Water is often orange-colored because of the presence of oxidized iron. Adit. An underground mine entry at sites where coal seams are exposed at ground level. Apple core. A complete hilltop (360°) left exposed by not backfilling the highwall. Approximate original contour. The surface configuration achieved by backfilling and grading the mined area so that be reclaimed land closely resembles the general pre-mining surface configuration and blends into and complements the drainage pattern of the surrounding terrain. Area mining. A surface mining method that is carried on in level to gently rolling topography on relatively large tracts of land. Active area mine pits may be several miles long. Arid and semiarid regions. Lands, generally west t of We 100% meridian, where water use by native vegetation equals or exceeds that supplied by natural precipitation, and rainfall is insufficient to support agriculture. Annual precipitation is normally 20 inches or less. Auger mining. A mining technique often used by surface mine operators when the overburden becomes too for the coal to be mined economically using traditional surface mining methods. Large-diameter (usually 2'-4') horizontal holes are drilled as much as 300 feet into We vertical Me of the coal bed by an auger. Like a bit used for boring holes in wood, coal augers consist of a cutting head with a screw-like extension. As the auger turns, the head breaks up the coal and the screw carries it back into a conveyor that loads it directly into a truck. Backfilling. The operation of refilling an excavation using material removed during the mining process. Bench. The level or flat working area at the base of the highwall that is excavated between the exposed coal seam and the original surface of the ground. Bucket wheel excavator. A continuous-digging machine that uses a rotating vertical wheel with buckets for large-scale stripping and excavating. Cessation Order. Order to cease mining issued to a coal operator by the regulatory authority due to severity of violations, Contemporaneous reclamation. Restoration of mined land that occurs as soon as practical after coal removal. Contour mining. A mining method commonly used in eastern mountainous topography where coal is removed in a narrow strip around the hillside. The extent of the cut into the hillside is determined by the depth of overburden at the highwall compared with the thickness of the coal seam. Daylighting. A term used to describe a surface mining procedure that exposes abandoned underground coal mine workings to enable removal of the remaining coal. Daylighting is followed by land reclamation. Dragline. An excavating machine, usually used in large, flat areas, that drags a bucket (which holds up to 220 cubic yards of material) toward the machine by cables, loads it with spoil, and then hoists it wit a boom up to 350 feet long, allowing the machine to excavate wide benches by depositing the spoil hundreds of feet away from the highwall. Grading. The process of smoothing the disturbed areas of the mine site, after the coal is removed, to closely approximate the pre¬mining terrain. Haul road. Any road constructed, improved, maintained, or used by mine operators and located within the permit area. Head-of-hollow fill. See "valley rill." Highwall. The cliff-like excavated face of exposed overburden and coal in a surface mine. Hydroseeding. Planting of seed mixed in a water medium. Water, mulch, lime, fertilizer, and seed are blended and sprayed onto regarded soil.

Jan 1, 1992

Develop and demonstrate a lightweight material that has low thermal conductivity and that would be suitable for placement using shotcrete methods. This material could be applied in deep, hot mines where mine drifts must be insulated. Its use would decrease mine refrigeration needs and reduce energy costs.

Jan 1, 1994

By J. E. Tiffany, Z. C. Gaugler

This supplement has been prepared to furnish information on amendments to the regulations that were approved by acting secretary of the Interior on June 24, 1946, while this report was in the press. Page 14, item 2, and page 20, item 4, have been amended by the addition of the following footnote: "Pending the development of a satisfactory multiple-shot permissible blasting unit, a blasting unit of Type II, Class A, covered by Federal Specification WB 411, December 31, 1941 (with or without Amendment 2, June 16, 1945), may be used until Decem- ber 31, 1947. Should a satisfactory multiple-shot permissible unit be made available prior to that date, this interim approval may be terminated." Page 14, footnote / has been amended to read as follows: "The use of charges over 1-1/2 pounds and not exceeding 3 pounds is approved pending further investigation. The approval, which may be withdrawn at any time, expires December 31, 1947, unless renewed. For charges over 1-1/2 pounds, the following additional requirements must be observed: (1) Shot holes must be 6 feet or greater in length. (2) Explosives must be charged in a continuous train with no cartridges deliberately deformed or crushed, with all car- tridges in contact with each other, and with the end cartridges touching the rear of the hole and the stemming, respectively. (3) The permissible explosive must be one showing toxic gas omission that will place it in either Class A or Class B."

Jan 1, 1947

By Lloyd A. Morley, Robert Stefanko

This report was prepared by The Pennsylvania State University, College of Earth and Mineral Sciences, ' Department of Mineral Engineering, University Park, Pennsylvania, under USBM Grant No. GO-133077. The grant was initiated under the Coal Mine Health and Safety Research Program. It was administered under the technical direction of the Pittsburgh Mining and Safety Research Center with Mr. G. J. Conroy acting as the technical project officer. Mr. J. A. Herickes was the grant administrator for the Bureau of Mines. This report is a summary of the work recently completed as part of this grant during the period 19 June, 1973 to 17 June, 1975. This report was submitted by the authors on 18 July, 1974. This technical report has been reviewed and approved.

Jan 1, 1974

To reduce air be respirable dust generated from emptying dry dust collectors on small truck-mounted drills used at surface coal mines.

Jan 1, 1995