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By J. W. Pall

The method of mining bituminous coal in Pennsylvania cannot be treated in an extended manner in this publication since this would require more space than justified. The general plan of operation of most mines is on the room and pillar system, using double entries from which the rooms are driven In the early mining in the Pittsburgh coal bed the "checkerboard" plan was much used, but this entailed a large loss of coal in the blocks of coal that were left standing. In recent years there has been a tendency towards the adoptions of the panel, room and pillar method, also the block system, which ad mats of concentrated mining within a relatively small section of the mine It is not unusual to use 4, 6, or 8 parallel entries for the panel development. The longwall advancing method has been tried in some of the thin beds of the central coal field, but so far it has not passed beyond the experimental stage. The average extraction' of coal throughout the State is 714 per cent, but it is estimated that 15 5 per cent of the loss is avoidable, so the actual extraction should approximate 87 per cent. Pennsylvania is exceptionally well provided with means of transportation by trunk lines, branches, and by intra State railroads, among which are the Pennsylvania, Baltimore & Ohio, New York Central, Buffalo, Rochester & Pittsburgh, Western Maryland, Bessemer & Lake Erie, Pittsburgh & West Virginia, Pittsburgh & Lake Erie, Erie, Monongahela Division, and Montour railroads, all of which reach some of the bituminous mines The Monongahela River furnishes water transportation for Allegheny, Greene, Fayette, and Washington counties During 1923 the coal traffic on this river amounted to 18,709,084 tons, and of coke, 385,426 tons Coal is moved on the Allegheny River also, the total in 1923 being 911,178 tons s.

Jan 1, 1928

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 D. S. Colby, E. M. SEELEY

The total production capacity of the natural-gasoline industry increased to 27,212,000 gallons (647,905 barrels) daily on January 1, 1950, from 21,322,000 gallons (507,670 barrels) daily on January 1, 1948. The rate of growth during these 2 years averaged 13 percent per year, compared with 9 percent per year from 1946 to 1948 and 6 percent from 1944 to 1946. The total number of operable plants on January 1, 1950, was 554, 5 more than at the beginning of 1948. The number of absorption plants increased by 12, the number of cycling plants by 7, and the number of combination plants by 4. The number of compression plants and charcoal plants continued to decrease. Absorption plants accounted for 67 percent of the total capacity on January 1, 1950, compared with 62 percent 2 years previous. Eighty-two per- cent of the expansion in these 2 years was in absorption-plant capacity. Cycle plants accounted for 24 percent of the total industry capacity at the beginning of 1950, compared with 27 percent on January 1, 1948. The average daily capacity of absorption plants increased from 38,400 gallons at the beginning of 1948 to 50,600 gallons at the beginning of 1950. During the same period, the average daily capacity of cycle plants decreased from 150,200 gallons to 144,100 gallons. Texas showed the largest gain in number of plants 13 absorption, 4 compression, and 4 cycling plants. The State accounted for 67 percent of the gain in capacity and on January 1, 1950 had 50 percent total national capacity. Louisiana followed with 7 additional plants. Pennsylvania reported 14 and West Virginia reported 13 fewer plants than in 1948. Most of these reductions were in the number of compression plants.

Jul 1, 1950

By Maria I. De Rosa

Table 10 and figure 4 show the number of fires and fire injuries occurring at the surface of underground metal/nonmetal and stone mines by state during 1990-2001. Table 10 also shows the injury risk rates, employees' working hours, and lost workdays. A total of 12 fires occurred in 11 states; 5 of the fires caused 5 injuries. The yearly average was one fire and 0.42 injury. Five fires with two injuries occurred at metal mines, five fires with two injuries occurred at nonmetal mines, and two fires with one injury occurred at stone mines. None of the fires involved contractors. The Ewhr value was 58 x 106 hr (Irr = 0.017), and the LWD value was 75. Nevada had the most fires (two fires and no injuries). Ohio, New Mexico, Missouri, South Dakota, and Idaho each had one fire with one injury. Of these states, Missouri had the highest injury risk rate value (In = 0.25). Table 11, partly illustrated in figure 5, shows the number of fires, fire injuries, risk rates, employees' working hours, and lost workdays by time period. The number of fires decreased during most of the six time periods. The number of fire injuries and employees' working hours decreased during all of the periods. The Irr values follow patterns similar to those shown by the injury values. Tables 12-17 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 6 shows the major variables related to fires for 1990-2001. Table 18 shows the number of fire injuries per number of fires causing injuries and total fires by year, ignition source, equipment involved, and location.

Jan 1, 2004

By D. B. Starkey

Investigation into the expressions of the field produced by a loop over a conducting half space or in an infinite conducting half space are well documented. Reasonably complex descriptions of the effects of stratification also are reported. However, a model which must contain all of these complexities because of transmission to depths of 15,000 feet and also include the pertibation of the field by a verticle cylindrical steel casing loses its facility in the field or for quick, accurate approximation to field magnitudes and phase. This paper describes the results of two field tests to determine the attenuation and phase versus depth and frequency of an electromagnetic wave (induction field). A simple two-layer model is postulated to predict the magnitude and phase of the induced field which does not require sophisticated computing tools. Correlation of the model with experimental results show agreement of most amplitude measurements to within 3 db and most phase measurements to within five degrees. The tests were conducted in a 7400 foot deep well in Nevada and an 11,000 foot deep well in Wyoming which had conductivities ranging from .0025 mhos/m to .25 mhos/m. The surface transmitting dipole had an area of ~ 10 6 feet squared and constant frequency signals of 1.5 Hz to 20 Hz were transmitted through the earth utilizing less than 65 watts of power. Model Description The magnetic field intensity components generated by a magnetic dipole immersed in an infinite homogeneous medium can be expressed in spherical coordinates as: [ ] where N, I, and (p a ) are the transmitting antenna turns, current, and effective area, respectively, and r is the range from the loops circumference to the measurement point. The case of interest for these experiments, however, is the special case of coaxial dipoles, i.e., ? = 180° . For this case H?= 0 and H reduces to: [ ]

Jan 1, 1973

By G. T. Lineberry, W. J. Wiehagen

This paper discusses a practical method for enhancing the performance of mining work crews. The method, described as the Work Crew Performance Model (WCPM), seeks to define performance variability within similar tasks of an underground work crew. Key components of the WCPM include: (I) job definition through task analyses; (2) the ranking of job elements by perceived cost consequence; (3) observational techniques to establish performance baselines; and (4) cost linkages between adherence to task procedures and measures of consequence for noncompliance. The components of this model emphasize a reliance on learning from a veteran work force and using that information to reinvest in strategies to enhance safety and efficiency. These strategies are not limited to technologic efforts but include consideration of the so-called "soft-skill technologies" aimed at reducing variability in individual performance and at effecting a continuous improvement in overall system effectiveness.

Mining and reclamation procedures that meet the requirements of SMCRA are illustrated on pages 8 and 9 for each of the three major surface coal mining methods -- area mining, contour mining, and mountaintop removal mining. The three methods involve the same basic steps: clearing the land of trees and other vegetation, removing topsoil and overburden, mining the coal, and reclaiming the land. Although all three methods would not usually occur on any single site, the illustration facilitates comparison of mining and reclamation methods and aids basic understanding of the reclamation processes that take place under SMCRA. Area Mining The area mining method is commonly used to mine coal in the flat to moderately rolling terrain found principally in the western and midwestern states. After the overburden is excavated down to a coal seam, the mining area is enlarged horizontally to expose more coal for removal. In the West, where coal seams are commonly 10 to 20 feet thick (and range up to 100 feet thick in the Powder River Basin of Wyoming), the life of some mines maybe more than 50 years. In the Midwest, coal seams are typically 3 to 7 feet thick and 75 to 100 feet below the surface. Because of the large expanse of area mines and their relatively unrestricted sites, enormous equipment is used to remove overburden and reconstruct the land. The area mining operation in the illustration is on land that was formerly used for farming. The drawing shows that the agricultural use is being reestablished immediately following reclamation. Mining is proceeding across the land toward the left side of the site. The initial excavation was made far enough away from the stream along the right edge of the site to prevent damage to the water supply. The coal under most of the site has been removed, and reclamation has been completed on some of the land. For example, some of the cattle in the foreground and those in the feedlot behind the silo are grazing on reclaimed land that has been mined. At the far left of the illustration, topsoil from the unmined area is being removed by scrapers, transported across the area of active mining, and immediately spread on the land on the right, which is being reclaimed. (Reclamation of mined land as soon as practical, as required by the Act, is called contemporaneous reclamation.) A

Jan 1, 1992

By Oliver Bowles

"A New Mica Company in China A report has been received from the American Consulate at Chungking, China, to the affect that a new company has been organized to operate a mica mine north of Ta-chien-lu, in the province of Ssu-Chuan. The company, which is entirely under Chinese management and control, has a working capital of $10,000. While comparatively new, the mine has been worked before, and apparently with some success. The mica is said to be of good quality. It is claimed that the deposit will supply a limited amount of mica that will cut in pieces a foot square or over, and larger quantities of smaller sizes. The chief difficulty is transportation, for it is reported that a ten days' journey, part of it over mountain trails, will be necessary to transport the mica from the mine to Yachow, the nearest practical waterway. It is probable, therefore, that the output of the mine will be limited.Necessity for Careful Trimming and Grading of MicaA recent report to the Department of Trade and Commerce, Ottawa, Canada, by Acting Trade Commissioner C. G. Venus, London, England, contains information which is of vital interest to mica producers in the United States. It is pointed out that mica exports from Canada to England show a gradual decline dur¬ing recent years, the figures being as follows: 1913- 1,383 cwt: 1914 - 1,225 cwt: 1915 - 1,864 cwt: 1S16 - 879 cwt: 1917 444 cwt: 1918 - 480 cwt. Shipments from India to England, on the other hand, show a steady increase from 40,178 cwt. in 1913 to 66,401 cwt, in 1918."

Jan 1, 1920

By Clarence O. Babcock

This report describes the results of a Bureau of Mines investigation in which an elastic inclusion, orebody, or mining system is replaced for purposes of analysis with an imaginary effective inclusion of rectangular shape that encloses the region. This effective inclusion has averaged physical properties that are directly related to the average inclusion stresses. The results were in excellent agreement with those predicted by Donnell's theory (2)2 for an isotropic elliptical inclusion in a state of plane strain for all height-to-width ratios and for all degrees of inclusion hardness from very soft to very hard. The results are exact for an isotropic circular inclusion and provide an easy method of evaluating the stresses obtained by cylindrical inclusions in boreholes when the Poisson's ratio for both host and inclusion equals 0.25 for plane strain or 0.333 for plane stress. The theory was also used to predict the average stresses in 48 finite-element models of single transversely isotropic inclusions of ovaloid and rectangular shape. An interesting and useful observation from this work was that the forces on elliptical inclusions in the x and y directions, produced by applied uniaxial stresses in the y and x directions, respectively, were equal in magnitude but opposite in sign when the applied stresses were equal. This occurred when the plane strain condition was used with a Poisson's ratio of 0.25. The practical usefulness of the method is given by treating a variety of mining problems: (1) The average stresses in an orebody of irregular shape; (2) the average stresses in single-level room-and-pillar mining systems; (3) the average stresses in multiple-level room-and-pillar mining systems; (4) the effect of mining sequence on the average stresses produced during mining; (5) the stresses in cylindrical borehole plug related to host rock stresses as a function of plug hardness; and (6) methods for simplifying finite-element analysis of complex structures.

Jan 1, 1974

The National Institute for Occupational Safety and Health (NIOSH) National Personal Protec-tive Technology Laboratory (NPPTL) and the Mine Safety and Health Administration (MSHA) conduct a Long Term Field Evaluation (LTFE) program to evaluate deployed self-contained self-rescuers (SCSRs). The objective of the program is to evaluate how well SCSRs endure the under-ground coal mining environment with regard to both physical damage and aging when they are deployed in accordance with Federal regulations (30 CFR 75.1714). This report presents ?ndings of the combined eighth and ninth phases of the LTFE. For these phases, over four hundred SCSRs were evaluated. The units tested include the CSE SR-100, Draeger Oxy K-Plus, MSA Life-saver 60, and the OCENCO EBA 6.5. The OCENCO M-20 was evaluated only in Phase 9. Testing was per-formed between December 2000 and April 2004. Results of the evaluation indicate that all SCSRs experience some performance degradation due to the mining environment. Observed degrada-tion varies from elevated levels of carbon dioxide, high breathing resistance, and reduced capacity. Mechanical degradation to the SCSR components included breathing hoses, chemical beds, outer cases and seals. The LTFE tests discussed in this report are different from tests performed for SCSR certi?cation to the requirements of 42 Code of Federal Regulations, Part 84 (42 CFR, Part 84). LTFE tests reported here are conducted to an end point, oxygen depletion, to enable comparison of the duration of new and deployed SCSRs. The method for obtaining deployed SCSRs for this evalua-tion was not a random selection from the deployed population of SCSRs. Although the results of these tests are useful for observing performance of the tested SCSRs, they are not representative of all deployed SCSRs. A new evaluation protocol, with revised sampling strategies, test methods, and reporting procedures, is currently being designed to enhance the generalizability of the results. This program will be implemented following completion of Phase 10 of the current LTFE protocol.

Jan 10, 2006

Roof falls continue to be the greatest single safety hazard faced by underground coal miners. During 1996-99, 44 coal miners lost their lives in rock falls, and nearly 2,400 were injured. In addition, nearly 6,000 noninjury roof collapses were reported. Roof supports are installed to protect the miners, but support system failures contributed to most of these incidents. Reducing the terrible toll taken by ground falls continues to be a major goal of research by the National Institute for Occupational Safety and Health (NIOSH). The purpose of these proceedings is to provide the mining community with a comprehensive survey of coal mine roof supports. Drawing on many years of research undertaken by the NIOSH Pittsburgh and Spokane Research Laboratories, this volume describes what types of support are available, how they work, and when they should be used. The major subjects covered include roof bolts, standing roof supports, cable supports, and longwall shields. Some special topics are also addressed, including an analysis of roof fall accident statistics, techniques for better skin control, material handling considerations, and longwall mining through recovery rooms. This proceedings volume also contains information on several important new technologies, which are described here for the first time: •Guidelines for selecting roof bolt length, pattern, and capacity that were derived from statistical analysis of the roof fall experience at 37 underground mines; •A new design method for longwall tailgate supports; and •A technique for measuring loads developed within cable bolts. The papers in these proceedings were presented at open industry briefings conducted by NIOSH on New Technology for Coal Mine Roof Support. The briefings were held in Norton, VA, Charleston, WV, Evansville, IN, Tuscaloosa, AL, Price, UT, Glenwood Springs, CO, and Washington, PA. The papers were also presented at the Mine Safety and Health Administration (MSHA) Preventative Roof-Rib Outreach Program (PROP) Seminar, which was held at the National Mine Health and Safety Academy near Beckley, WV.

Jan 10, 2000

By Thomas O. Glover

Economic growth in Cameroon was restricted during 1987 owing to a decrease in oil prices during 1986 and the falling value of the U.S. dollar in 1987. The yearly budget reflected a significant drop in revenues and expenditures. Taxes on imports and some exports were increased to raise revenue. The shortage of revenue and the lack of liquidity had restricted the Government's operation and investment programs. External public debt reached an estimated $3.2 billion2 representing 20.8% of the estimated gross domestic product (GDP) of $12.3 billion. The Government operated at an 8.7% deficit in 1987. The GDP growth rate had fallen to 0.6% in 1987 and was projected to remain at that level in 1988. Economic planning was managed through a series of 5-year plans. The country was under the sixth 5-year plan, which would end in 1991. The plan stressed balanced development as one method to achieve the desired results. Sources of revenue for the year included direct and allied taxes (31.2%). customs collections (31.0%), and oil royalties (28.0%). The oil royalties in 1987 represented a larger part of the budget than in 1986. In January 1987, eight African oil exporting countries, including Cameroon, formed the African Petroleum Producers' Association (APPA). The eight countries represented about 80% of the total African oil production of 5.2 million barrels per day in 1987. Cameroon produced approximately 3% of total APPA oil production. Cameroon produced approximately 68.5 million barrels of crude oil in 1987, slightly less than that produced in 1986. Earnings also fell in 1987, not only from falling production, but also from declining oil prices and the fall in value of the U.S. dollar on world markets. Oil had been the main stimulus of Cameroon's growth throughout the past decade, and a key generator of export revenues and financial resources for the economy.

Jan 1, 1989

By Ronald D. Hill, Elmore C. Grim

1. Potential groundwater pollution resulting from large-scale surface mining in western states should be evaluated. 2. Criteria should be developed for the design, construction, operation, and abandonment of sediment ponds for maximum removal of suspended solids. 3. Methods should be developed for reducing suspended solids discharges from surface mines to less than 30 milligrams per liter. 4. A manual should be developed in the form of guidelines for sediment and erosion control planning and implementation. These guidelines must be designed to cover all phases of the coal surface mining operation (i.e., before, during and after mining). 5. A mine road manual should be developed for use by surface mine operators and State and Federal Agencies. Erosion, water control, and dust control should be covered in detail. 6. The block-cut, head-of-hollow fill, and mountain-top removal methods and techniques of contour mining should be evaluated, designed, and ultimately demonstrated in steep, mountainous terrain. Designs should be prepared for single and multiple seam applications. The demonstrations must show that these mining systems will secure rapid achievement of reclamation require¬ments and provide maximum, safe, economic coal recovery in an environmentally safe manner. 7. A Blasting Manual should be developed for use by industry and enforcement agencies. Stress should be placed on how to keep vibration levels and air blast pressures well below accepted safe criteria. Also, methods that can be used to control noise should be listed. 8. Investigations should be conducted on the effect of continued vibrations from blasting on structures that are near quarries. 9. Additional guidelines need to be developed for sampling and analysis of overburden material and associated coals for trace elements and noxious strata. Samples are extremely sensitive, and the source and manner of their collection, handling, storage, and treatment, as well as the techniques of analysis, need to be developed and described. This information can be used to predict possible future problems.

Jan 1, 1974

To evaluate the potential for dust reduction, during blasthole drilling, of water or foam applied directly into the drill hole. Approach The Bureau of Mines tested a through-the-drill-steel water and foam injection technique in two noncoal mines to evaluate the method's potential for greater dust reduction. The tests were performed by drilling a series of blastholes for an entire face (a 90 minute time-period). For the first 45 minutes of drilling, foam or water was applied through the drill steel. Blowing ventilation was supplied to the entry about 50 feet from the face. The dust concentration measurements were made by a Real-Time Aerosol Monitor (RAM-I), and the data were read out on a strip chart recorder. The evaluation test results showed that the water or foam injection technique, when used on localized dust sources, can be an extremely effective dust control method. Small amounts of water used in this method have also allowed it flexibility to be used in water-soluble ores such as salt, gypsum, anhydrite, and trona. How The System Works Water or foam is mixed with compressed air (approximately 100-120 psi) with suitable metering systems and forced through the drill steel into the blast hole at the point of dust generation. Because the water or foam is applied at the source, minimal quantities of liquid are needed (0.2 to 0.6 gpm). These low flowrates are sufficient to just moisten the dust emerging from the blast hole, thus eliminating a major source of airborne dust. The wet drilling procedure also eliminates a second source of dust. With dry drilling, the dust from the blast hole falls to the floor. Since this can be a 15-ft drop or more, the impact can send the dust billowing up from the floor, adding to the airborne dust. With wet drilling, the moistened dust merely dribbles down the face.

Jan 1, 1982

By L. C. IlsLey

A specially recommended cable is a rubber-sheathed cable that has met the minimum performance requirements for cables as set forth in Schedule 20. The first in the series of recommended cables was listed September, 1930, by an ad- vance notice published as Information Circular 6375 which described the conditions under which the cable tests were made. Since that time six additional cables have met the test re- quirements and have been specially recommended. The complete list of specially recommended. cables is as follows: Specially recommended-cables Cable Symbol No. Hazacord No. 2 BM1 Stranding 19 x 7 Hazacord No. 3 BM2 do. Hazacord No. 4 BM3 do. Super-service No. 3 BM4 7 x 19 Super-service No. 2 Super-service No.. 4 BM5 do. BM6 do. Super-service No. 4 BM7 7x 7 Manufacturer Hazard Insulated Wire Works (division of the Okonite Co.) Do. Do. Rome Wire Company (division of the General Cable Corporation) Do. Do. Do. The cables listed were all twin (parallel duplex) cables having outer belts or cov- erings of approximately -inch high-grade rubber compound, and have the same general appear- ance and relative dimensions as the types of twin cables in general use. The cables were tested under conditions designed to show their approximate perform- ance under mine conditions. Only twin-type cables have met these test conditions. Although the recommended trailing cables are much better and safer for mine use than other cables and withstand being run over by a 7-ton car, they should not be considered as 100 per cent safe. The 7-ton car test represents the minimum limit requirement effective at present under Schedule 2-C, but the test car operates on a straight and level track, and thus does not represent the more severe conditions of mine use such as might result from uneven and curved tracks.

Mar 1, 1931

By G. E. McElroy, A. S. Richardson

"The Bureau of Mines, in cooperation with the Anaconda Copper Mining Co., has conducted a series of experiments an air measurement in fan-pipe installa¬tions in a Butte mine during the fall and winter of 1922-3. The chief purpose was to determine the friction factors for different types and sizes 3f fan piping, but much attention was devoted to methods of air measurement, not only with respect to the methods used for friction factor tests, but also to com¬parison with other methods.The air flow was measured simultaneously at two points 380.6 feet apart in six different fan-pipe installations, each over 500 feet in overall length, in a rock cross cut adjacent to an air shaft,The air pressure was regulated by two sinoco multivane fans, driven by 7 ½ h.p. motors, the fans being connected in tandem so that one discharged into the intake of the other through a short connector and the latter discharged into the line through a straight connection equipped with a honeycomb of 4-inch squares or S radial vanes to prevent spiral flow of air, At each point where it was desired to measure the air flow, measuring sections equipped with piezometer rings pierced for easy insertion of pitot tubes, thermometers, etc. Piezometer static pressures were used in all the tests as standard, and dynamic or total pressures only were obtained with the pitot tubes, except for purposes of comparison.The tubes had special guide blocks, designed especially for underground work. To insure greater accuracy two tubes were used simultaneously, in order to obtain the velocity pressure at the center of the section simultaneously with that nearer the circumference, so that the mean velocity would be determined as accurately as possible. The tubes were held in proper place by means of flat guide boards. Velocity pressures were measured in manometers."

Sep 1, 1923

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

6. Computer Simulation of Mine Evacuation Analysis of mine evacuation involves manipulating a large number of interacting variables, such as mine passages, hoist movements, miner position etc. , which makes the problem very difficult to solve without use of a digital computer. Therefore, under this contract, a computer program is written to simulate evacuation of a mine under different configurations. The simulation input variables include characteristics of the mine, expressed in the form of a network of passages, properties of hoists and hoisting strategies, initial miner positions, ventilation and compressed air velocities, stench warning system and self-rescuer capabilities. The simulation can be carried out for cases in which there is no fire, i. e , fire drill simulation, or for cases in which there is a fire at any arbitrary location. The fire is assumed to generate gases which impede movement of miners in the gaseous region. However, the thermal effect of the fire on ventilation or on the miners is not considered. The simulation output includes the evacuation time for each miner, movement of the hoists, propagation of smoke through the mine passages and smoke exposure time of the miners. Details of the mine evacuation program are summarized in Appendices A and B Appendix A describes structure of the program and its capabilities. The flexibility of the program and its suggested uses are demostrated by a number of illustrative examples Appendix B is a user' s manual for the program which includes instructions for program use and explanation of the logic employed in the program. A computer listing and printout of a typical output are also included in the Appendix B The ten illustrative examples summarized in Section A 4 (Appendix A) provide proof of validity of the program and help make certain inferences about mine evacuation. The first example, which is simulation of an actual mine fire drill conducted in a mine, has predicted evacuation time within 5 percent of the actual evacuation time in the fire drill, demonstrating thereby, the ability of the program to make accurate predictions.

Jan 1, 1976

To prevent injury to miners caused by violent whipping of mining machine trailing cables. Approach: The hydraulic cable controls are adjusted to reduce whip by visual reference of the cable sag to the height of the cable guide. How It Works: The cable sag is adjusted by visually estimating its height above the ground, at a specific reference distance behind the machine. This reference distance is measured horizontally back from the point where the cable leaves the cable guide. The Reference distance is 2H where H equals the height of the cable guide above the floor. See Figure 1. Cable sag should be less during rewinding than during unwinding. During cable unwinding, the cable height (at the refer¬ence distance) should equal 1/31-1. During rewinding, the cable height should equal ½ H. Field tests were made on several manufacturers' equipment after adjusting cable sag as above. Cable whip was greatly reduced for all, and whip was almost eliminated on a shuttle car equipped with a Joy Manufacturing Company 500108-104 cable reef and the newer (nonporous) shuttle valve. The following directions are for adjusting cable sag on a shuttle car equipped with a Joy Manufacturing Company 500108-104 Cable Reel equipped with the newer shuttle valve. Cable sag can be adjusted on machines equipped with other cable reels and valves by referring to the manufacturer's manual and making the appropriate cable valve adjustments.

Jan 1, 1976

? A roof bolter reaches for a lever while guiding the drill with his other hand. Since he's watching the drill and many of the controls look and feel alike, he hits the wrong control and crushes his hand. ? Six hours into the night shift, an ore truck driver dozes off. The truck plows over the berm and down into the pit. ? Fleeing a afire, a face crew sees smoke in the intake entry. Assuming the fire is ahead, they cross over to another entry, but soon encounter even worse smoke. These very different accidents have at least one factor in common: the human factor. The actions, decisions, thoughts, or perceptions of one or more humans contributed to the accident. These are just a few examples of safety problems researched by the Human Factors Group of the Pittsburgh Research Center, U.S. Department of Energy.

Jan 1, 1998

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

Jan 1, 1974