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By R. V. Ramani, C. B. Manula, A. Owili-Eger

ANALYTICAL PRESSURE - VOLUME COMPUTATIONS FOR THE MINE PROTOTYPE A new coal mine is projected, with entrance by slope 1,500 feet long. Nine main entries will be standard for development, five as intake and four as return. One return shaft is planned near the slope bottom, and an intake shaft and portal are planned 5,000 feet north of the slope bottom. The slope will have an area of 150 square feet and a perimeter of 55 feet. A belt and supply track will be within the slope. The return shaft will be circular with a diameter of 18 feet and will be 500 feet deep with an escapeway. Two hundred feet of the shaft and 500 feet of the slope will be concrete lined. Select the fan to operate five units per shift and drive the 5,000 feet to a proposed new portal, using the slope for an intake. Two main splits are planned with the maximum of three units on any split. The amount of air desired at each unit is 25,000 c.f.m; a shop at the slope bottom will require 10,000 c.f.m. In the solution of this or any similar problem, the first step is to determine the resistance factors. CALCULATION OF R FACTORS Slope area = 150 sq. ft.; Perimeter = 55 feet; Length = 1,500 feet. The friction factor K must be established. Five hundred feet of the slope is smooth lined, moderately obstructed by belt; K = 35. The remaining 1000 feet is in sedimentary rock and moderately obstructed; K = 85.

Jan 1, 1975

By J. L. Ellenberger

The National Institute for Occupational Safety and Health (NIOSH) has continued the research role of the former US Bureau of Mines (USBM) to engineer techniques that will reduce the hazards in the mining workplace associated with coal bumps. Recent research focused on a longwall coal mine in Utah with overburden greater than 750 m (2,500 ft) containing several massive sandstone units. The primary field instrumentation at the site was three-dimensional, full waveform, autonomous microseismic arrays placed underground and on the surface in order to surround the active multi-panel longwall district. The purpose of these arrays was to help investigate the strata mechanics associated with the redistribution of stress and the associated gob formation of the longwall. Specifically, the seismic arrays were used to determine the timing and location of the failure in the strata surrounding the active mining. Overall 13,000 seismic events were detected and located with on-site processing during the five months the panel was being mined, including a magnitude (ML) 4.2 event. Of these, a smaller subset of 5,000 well-located events was selected during post-processing to form a consistent data set for analysis in this paper. From this data set, it was observed that the seismic events generally occurred in advance of the longwall face, both above and below the panel, consistent with failure of the strata in the forward stress abutment zone. Also, the occurrence of the ML 4.2 seismic event within 150-180 m (500-600 ft) of a deep cover longwall face with no associated bump caused a re-evaluation of the nature of the connection between seismic activity and coal bumps.

Jan 1, 2002

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

Ahmed, M.,• "Development of an Integrated Control System for Mine Ventila¬tion and Firedamp Drainage," Mining Engineer, Vol. 127, No. 91, April, 1968, pp. 382-392. Andrews, J. W., "U. S. Mine Ventilation Standards," Paper presented at the International Mine Ventilation Congress, Sept., 1975. Boyle, J. A., and Conn, 0. S., "The Control of Mine Ventilation Utilizing Multiple Main Fans," Paper presented at the Seventy-second Annual CMIA Meeting, Pittsburgh, December 1958. Collinson, P. L., and Vance, W. E., "Mine Ventilation Planning," The Mining Engineer, Volume 121, No. 14, 1961, pp. 141-156. Committee on Industrial Ventilation, Industrial Ventilation, 12th Edition, 1972. Grever, R. E., "Automatic Monitoring of Ventilation Conditions in European Coal Mines," Symposium on Engineering Systems Design for Mine Safety, Michigan Technological University, August 1973. Hall, C. J., Airflow in Mines - Thermodynamic and Motive Column Analyses, The Book Concern, Printers, Inc., Hancock, Mich., 1967, 263 pages. Hargraves, A. J., "Planning and Operation of Gaseous Mines," Canadian Mining and Metallurgical Bulletin, Vol. 66, No. 731, March 1973, pp. 119-128. Harris, E. J., "The Fluid Network Analyzer as an Aid in Solving Mine Ventilation Distribution Problems," SME-AIME Transactions, Vol. 228, 1963, pp. 391-395 Higgins, J., and Shuttleworth, S. E. H., "A Tracer Gas Technique for the Measurement of Airflow in Headings," Colliery Engineering, November 1958, Vol. 35, pp. 483-487. Kaiser, K. M., and Bhowmick, B. C., "Recent Developments in Mine Ventila¬tion Instrumentation," Journal of Mines, Metals & Fuels (INDIA), June 1974, pp. 155-162. Kalasky, J. D., and Krickovic, S., "Ventilation of Pillared Areas by Bleeder Entries, Bleeder Systems, or Equivalent Means," Trans¬actions AIME, Volume 254, December 1973, pp. 284-291. Mahajan, J. K., "Ventilation Planning for a Deep Metal Mine," Min. Geol. Met. Inst. India, Volume 69, 1972, pp. 31-38.

Jan 1, 1977

By Maria I. De Rosa

Table 55 and figure 19 show the number of fires and fire injuries for stone mills by state during 1990-2001. Table 55 also shows the injury risk rates, employees' working hours, and lost workdays. In all, 118 fires occurred in 33 states. Seventy-six of the fires caused 82 injuries (including 8 fires and 6 injuries involving contractors). The yearly average was 9.8 fires and 6.8 injuries. The Ewhr value was 873 x 106 hr (In = 0.019), and the LWD value was 1,911. Missouri had the most fires (16 fires and 9 injuries), followed by Pennsylvania (15 fires and 14 injuries), Michigan (9 fires and 5 injuries), and Virginia (7 fires and 5 injuries). Of these states, Virginia had the highest injury risk rate value (In = 0.09 1). Table 56, partly illustrated in figure 20, shows the number of fires, fire injuries, risk rates, employees' working hours, and lost workdays by time period. The number of fires and fire injuries decreased during most of the periods, with a sharp increase during the last period. The number of employees' working hours increased throughout the periods. The In values follow patterns similar to those shown by the injury values. Tables 57-63 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 21 shows the major variables related to fires for 1990-2001. Table 63 shows the fire injuries per number of fires causing injuries and total fires by year, ignition source, equipment involved, and location.

Jan 1, 2004

By Robert C. Hickman

"INTRODUCTION Two holes were drilled on the G. S. Stiner zinc prospect, in the Lead Mine Bend area of Union County, Tenn. The holes were drilled in the vicinity of an area of gossan float and were bottomed in the Maynardville formation of the Nolichucky shale. Drilling was started January 24 and completed February 16, 1947. The total footage drilled was 421.2 feet.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigative Work, and prepares the final report. The Metallurgical Branch, Cliver C. Ralston, chief, analyzes samples and makes beneficiation tests.The project was under the general supervision of Mitchell H. Kline, chief, Raleigh Division, Mining Branch, Raleigh, N. C.LOCATION AND ACCESSIBILITYThe prospect is located approximately 20.5 miles southwest of Tazewell, Tenn. It is reached from Tazewell by driving 13.8 miles southwest on State route 33, thence 6.8 miles over graveled roads in a northwesterly direction to Stiner's general store. The drill holes are located in the bottom land northeast of the store (fig. 1 and 2)."

Feb 1, 1948

By Robert P. Vinson, Fred N. Kissell, Edward D. Thimons

Because of the high number of accidental methane gas ignitions in metal and nonmetal mines, the Bureau of Mines searched for a simple guideline that would allow mine personnel to evaluate the methane hazard in a given mine. Air samples were collected by the Bureau in 53 metal and nonmetal mines and analyzed for trace evidence of methane gas. Samples were collected in the returns and at the working faces. Those mines classified as gassy by the Mine Safety and Health Administration had a significantly higher average methane concentration than those classified as nongassy. Of the 9 gassy mines sampled, 7 had methane concentrations above 100 ppm, whereas only 1 of the 44 nongassy mines had a concentration above 100 ppm. The 100-ppm concentration may be used as a simple and convenient guideline for forecasting the methane hazard in a mine, whether or not the mine is classified as gassy. There was no consistent correlation between commodity mined and methane concentration, nor was there a correlation between mine depth and methane concentration. Neither of these factors can be considered a guideline for predicting methane hazards.

Jan 1, 1979

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 Steven J. Page, John A. Organiscak, Thomas Mal

Monitoring the miner respirable quartz dust exposure for compliance with U.S. federal regulations is mandatory to protect the health of coal miners. However, there is no technique available for the direct measurement of the respirable quartz dust concentration in the mining environment. The only means to estimate the respirable quartz dust concentration is to perform an analysis of the respirable dust sample collected, which contains both coal and quartz dust as well as other mineral constituents. For samples collected at coal mines, the U.S. Mine Safety and Health Administration (MSHA) utilizes the P7 method for respirable quartz analysis. The objectives of this work are to 1) evaluate the performance of the P7 method on field samples of low quartz mass loadings, 2) evaluate the magnitude of dust mass spatial variability within an enclosed cab environment, and 3) estimate the subsequent propagation of error in calculating the per. centage of quartz over a broad range of mass and quartz filter loadings at a surface coal mine. These objectives were achieved by obtaining surface coal mine dust samples over a 9-month time period in enclosed cabs of three drills and three bulldozers. By measuring weighing precision and using reasonable estimates for sampler variability, the dust mass spatial variability component was calculated by difference. The results show that 1) the P7 method can be precise and linear with quartz mass loadings as low as approximately 5 µmg of quartz, 2) the dust mass spatial variability, even within an enclosed cab environment, is the dominant factor of variability in propagation of error in estimating the quartz content of the obtained dust samples on a percentage basis, and 3) weighing precision is not a significant factor in error propagation. In addition to the enclosed cab samples, samples from eight surface coal mine drills were collected at various locations exterior to the drill cab. Significant data scatter at these outside locations strongly suggests that the ambient dust mass spatial variability has a significant effect on the propagation of error in estimating quartz content of the dust samples on a percentage basis.

By Edward Thimons, William A. Hertbrink

The effect of wind speed upon aerosol penetration into an idealized enclosure was studied The idealized enclosure was a painted plywood box that was 1 2X1 2 XI meters in volume Two fans supplied 1 7 m3 /min of filtered air to this enclosure at a static pressure of 2 8 mm of water The enclosure had a 7 5 cm diameter vent port which was isolated from the air flow around the enclosure To simulate holes in real enclosures, three 16-cm diameter holes were drilled on the front and back sides of the enclosure This simulated enclosure was placed in a tunnel-like structure The air flow from an ultra-light air craft was directed at the front of the enclosure The air speeds were varied between 14 and 36 km/hr as measured by rotating vane anemometer Static pressure in the enclosure was measured with an electronic manometer Two optical particle counters measured the particle number concentration of particles between the 0 35 to 0 5 µm inside and outside of the enclosure Aerosol penetration into the enclosure was computed as the ratio of the aerosol concentration inside the enclosure to the concentration outside of the enclosure The enclosure static pressures measured increase from 2 8 to 3 4 mm of water (P=00001) Aerosol penetration into the enclosure increased linearly with air velocity above 20 km/hr Theoretically estimated penetrations were correlated with observed penetration into the simulated enclosure When simple linear regression was used to model the observed penetration as a function of the estimated penetration, the value of the slope was 0 69±0 12 and the P value for the regression model was less than 0 0001 These results indicate that enclosure static pressure needs to be higher than the wind's velocity pressure in order to minimize aerosol penetration into these enclosures

Jan 1, 1999

By A. J. Farstad, R. G. Olsen

The Coal Mine Health and Safety Act of 1969, passed by Congress in the wake of the disaster at Farmington, West Virginia, led to an extensive study by the National Academy of Engineering of the problems involved in coal mine safety. One of the results of this report and subsequent research conducted by the U. S. Bureau of Mines has been the investigation of electromagnetic techniques for the location of trapped miners after a mine emergency. The Westinghouse Georesearch Laboratory has been involved in both the 2 theoretical and field studies relating to this problem. A compact personal beacon transmitter has been developed which can be attached to and powered by a miner's lamp battery. A compatible lightweight loop antenna package has also been developed which can be easily carried on a miner's belt. This antenna can be quickly deployed on the mine tunnel floor. For the purpose of calculating its electromagnetic fields on the earth's surface, the loop can be considered to be a magnetic dipole buried in the earth. (The earth is assumed to be homogeneous and to have a conductivity of s mhos/m.) The surface of the earth is assumed to be uniformily sloping and the transmitter dipole oriented as in Figure 1. The fields on the earth's surface can be computed by using a superposition of the fields of a 4 vertical magnetic dipole3 and of a horizontal magnetic dipole in proportions which depend on the slope of the terrain. In the case of level terrain a null in the horizontal magnetic 5 field occurs on the surface directly above the dipole. This null is designated as the apparent source location and is the criterion by which the source is located. The criterion was tested at two hardrock mines and two coal mines in the fall of 1972. The apparent source locations were compared to actual locations determined by conventional surveying techniques. It was found that due to nonlevel terrain the apparent and actual source locations differed by up to 13 meters. This discrepancy can be resolved by an examination of the fields of a source beneath uniformly sloping terrain. Figure 2 shows the experimental and theoretical results for a

Jan 1, 1973

By Douglas D. Reynolds, Tarek Deeb, Qunli Liu

Landmines are a great threat to military vehicles and their occupants. Mine blasts can completely destroy vehicles and kill all the occupants or disable the vehicle and leave the occupants severely injured. Injuries sustained during a landmine blast come from fragmentation that enters the vehicle through a hull breach, hot gasses expanding through the vehicle, or shock created from the extreme pressure of the blast (Lafrance, L.P. 1998). Mitigating the high acceleration experienced by the occupants during survivable mine blasts is the focus of the research being addressed in this paper. Method The objective of the project reported in this paper was to prove the feasibility that pneumatic seat technologies that employ light-weight, foam-filled, inflatable air bladder seats and seat backs can be used to protect the crews of lightweight combat vehicles against the detrimental and injurious effects of mine blasts. This protection includes reducing the shock energy experienced by seated vehicle crews during mine blast initiation and at vehicle slam-down to below potentially injurious levels. Figure 1 shows a schematic representation of the proposed lightweight, foam-filled, inflatable mine blast attenuating seat. It will consist of specially designed interconnected seat and seat back lightweight, foam-filed, air bladders that are supported by a rigid frame. [ ] Results Air gun tests and finite element analyses were conducted to determine the effectiveness of a light-weight, foam-filled, inflatable air bladder seat shock isolation system in isolating a vehicle occupant from the injurious effects of a mine blast. Figures 2 through 5 show analytical and experimental results associated with a 65.8 kg mass resting on an inflatable air bladder that is exposed to a shock input.

Jan 6, 2006

By Bob Thomas, Syd Peng, Quanzhong Gu, Gene Wilson, Gerald L. Finfinger

Identifying the properties of overlying rocks in underground mining operations is important to ensure the appropriate roof support design is used to maintain stability of the mine entries. Recently J. H. Fletcher & Co. developed a monitoring and control system for roof bolters for the underground mining industry. The system records the drilling parameters used during roof bolt drilling and the information can provide insight into the physical properties of the roof strata. The parameters include thrust, rotational speed, torque and velocity and the measurements are collected every 0.1 second during the operation. The drilling parameters were analyzed to determine the application of identifying the strength of rocks being drilled from the measurements. The data was converted into the specific energy of drilling which is a measure of the amount of energy required for removing a given unit of rock during a drilling operation. The laboratory studies completed to date indicate a fairly high correlation between the specific energy of drilling and the unconfined compressive strength of :he rocks that were drilled. Additionally, the drilling parameters were shown to be effective for identifying the presence of fractures or bed separations between rock layers. The thrust, torque and specific energy of drilling were all good indicators for identifying the fractures or separations. Regardless of the drilling parameters used during the drilling experiments, the location of the fractures were identified. In order to determine the application of the drilling parameters for identifying roof rock properties, two series of experiments were conducted. The first series of experiments used three "manufactured" roof layers that had various rock samples embedded in concrete blocks. The rock samples included three types of sandstone, marble, and argillite. Another concrete block was poured with foam inserts to simulate large bedding separations (2 to 8-in). Two other manufactured blocks were constructed using high-strength concrete with cardboard layers embedded to simulate smaller fractures or bedding separations. The size of the cardboard layers varied from 1/8- to 1-in thick. One of the blocks had the cardboard layers embedded at an inclined angle to determine the effect of the orientation on the drilling parameters. A series of experiments was conducted with the rotational speed and the penetration rate held constant and the thrust and torque allowed to vary. The information collected from the experiments is used to determine the application of the drilling parameter measurements for identifying rock properties, fractures and bedding separations.

By C. J. Johnson, C. J. Bise

"The occurrence of Coal Worker's Pneumoconiosis (CWP) ·has been potentially linked with several characteristics of coal such as rank, volatility, percent content of ash and non-coal components, quartz content, and the presence of several trace elements. According to the National Research Council, numerous epidemiological Studies: indicate that the incidence of CWP varies significantly with the composition and/or the concentration of the coal mine dust.Although advances in dust suppression techniques have markedly reduced respirable dust levels in underground coal mines, the National Research Council has concluded that chemical characteristics of respirable dust from different coal seams should be studied. With this objective in mind, research has been conducted in underground coal mines located in the eastern and mid-western United States, and in the laboratory to characterize the elemental composition of mining-generated airborne dust and laboratory-generated dust derived from samples taken from these mines. The goal of the research is to determine if a relationship exists between mining-generated and laboratory-generated dust from the ·same mine. Results of this research will be presented. ,"

Jan 1, 1988

This chapter presents data on occupational exposures from several sources. Data from compliance samples obtained by MSHA inspectors are presented in table 6-1 for coal mine dust and silica dust, and in tables 6-2 through 6-6 for metal fumes. Since these samples were taken for compliance monitoring rather than as part of a survey of the industry, it is difficult to predict how well they indicate actual exposures for all mining operations. In the coal industry, 7.8% of all respirable dust samples during 1986-1995 were above the permissible exposure limit (PEL). Of silica dust samples obtained during the 10-year period, 23.7% were above the PEL in coal, 16% in metal, 10.8% in nonmetal, 9.1% in stone, and 7.6% in sand and gravel. Of metal fume samples, silver samples showed the largest percentage above the PEL-approximately 48% of samples in both metal and nonmetal. Tables 6-7 and 6-8 present data on noise exposures from the MSHA "dual threshold" survey, which was published in the Federal Register [61 Fed. Reg. 66347 (1996)] as part of a proposed rule change for occupational noise exposure in mining. This study examined a group of samples obtained during 1991-1995 and compared the percent of samples that were above two separate specified limits. The first limit was the current noise standard, a time-weighted average of 90 dBA, calculated to include only exposures at 90 dBA and above. The second limit was a time-weighted average of 85 dBA, calculated to include exposures at 80 dBA and above. Tables 6-8 and 6-9 refer to musculoskeletal overload conditions examined in the National Occupational Health Survey of Mining (NOHSM) [NIOSH 1996]. Table 6-8 shows the operational definitions for each condition; table 6-9 shows the percentage of the workforce potentially exposed, by commodity. Across all commodities, a large proportion of workers were exposed to musculoskeletal overloads due to positioning of the neck and back; positioning and motion of the forearms, arms, and shoulders; heavy lifting; and positioning and movement of the lower limbs. The recorded overloads were defined in the survey and did not exceed any NIOSH, MSHA, or OSHA guidelines for musculoskeletal overloads. Further information on this survey appears in appendix A.

Jan 5, 2000

By Christopher Mark, Anthony T. Iannacchione

Falls of ground continue to be one of the most serious causes of injury to U.S. miners. Of the 256 fatal injuries that occurred in mining between 1996 and 1998, 59 (23%) were caused by falls of ground (Table 23.1). Falls of ground affect some sectors of the mining industry more severely than others. For instance, nearly 40% of the 98 coal mine fatalities between 1996 and 1998 were caused by falls of ground. Underground miners are at much greater risk than surface miners. Nearly half (45 out of 101) of underground mine fatalities were attributed to roof, rib, and face falls, while only 6% of the 155 surface fatalities were caused by falls of highwalls or slopes. The goal of this chapter is to provide guidance to safety professionals tasked with preventing ground fall injuries. This chapter combines an analysis of the Mine Safety and Health Administration's (MS HA) accident and injury data with a survey of industry "best practices" to safeguard miners from ground falls. Ultimately, this approach can help to form the basis of a sound, proactive ground control program for the mining industry. SOURCES OF DATA All the injury data examined in this study were derived from MSHA's fatal investigation reports and the MSHA accident database. Because falls of ground often result in serious injury, MSHA "Fatalgrams" and fatal investigation reports provide a useful snapshot of ground control issues in the mining industry. These reports are available to the public (on the M FHA Web site at www.msha.gov). Fatalgrams, are one-page summaries that are usually published within a month of an accident. They contain very basic information about the accident with a graphic and a short section on relevant best practices. Fatal investigation reports are the official accident investigation reports filed by MSHA personnel. These reports contain general information about the mine, a, description of the accident, physical factors involved in the accident, a conclusion, and enforcement actions, Enforcement actions typically identify citations and discuss violations to the Federal Mining Law. MSHA also maintains comprehensive statistical data on the mining industry's accident and injury record. The law requires that mines file a report on every reportable accident that occurs, containing information on the accident's location, severity, classification, activity, and nature of injury A short narrative is generally included as well. Accident reports can be searched by many of the above fields.

By F. E. Cash

"In the interest of accident prevention it is felt that a report of the measures taken during the past four years toward the reduction of fatal accidents in Alabama, especially in preventing falls of roof and coal, will be of interest throughout the mining districts.In order to determine the primary factors in the reduction of fatal accidents from falls of roof and coal, the operators, State Inspection Department, and the Alabama council of the Holmes Safety Association were asked: ""What has your organization done to help in the reduction of accidents from fails of roof and coal?"" The responses to this question have made this report possible.To bring out briefly the reduction in fatal accidents from falls of roof and coal as well as from all causes, the following three tables have been prepared.These statistics have been compiled from the records of the State Inspection Department.In the order mentioned, it is felt that credit for the reduction in fatal accidents from falls of roof and coal should be given to the individual operating companies, the State Inspection Department, the Alabama council and chapters of the Holmes Safety Association, and the Alabama Mining Institute. The individual operating companies naturally head the list in that they are directly concerned from a humanitarian as well as a financial point of view. The State Inspection Department through frequent and thorough inspections and by providing necessary statistics is largely responsible for the reduction. The Alabama council and its affiliated chapters of the Joseph A. Holmes Safety Association through its publicity and education reaches a large number of employees throughout the mining district. The Alabama Mining Institute defrays the council expenses and thus makes possible much of this service to the Alabama mining industry.In 1925 there were 49 fatalities, equivalent to 115,169 man days per fatality, from falls of roof and coal, which was by no means a good record; in 1926 the number and frequency of accidents were reduced to 42 fatalities and 149,096 man days per fatality. When in 1927 the fatalities from this cause mounted to 61 and the man days per fatality were reduced to 89,903, it was quickly realized that more concentrated efforts must be exerted to reduce such accidents.As early as August, 1927, at which time the fatalities from falls had reached a total of 31, the following letter from the Chief Mine Inspector was written to each operating company in the State and was the initiation of a very strenuous campaign by all parties concerned towards the reduction of accidents from falls of roof and coal."

Nov 1, 1929

By H. M. Lawrence

"In the land-pebble district of Florida a lively interest in the possibilities of obtaining increased recoveries of phosphate rock is evident. Research in several directions is being carried on by companies operating in the district to increase the yields obtained by the washing plants. The Bureau of Mines is cooperating with this research program to promote more efficient plant practice and to avoid unnecessary depletion of mineral resources.Washing practice, as carried on in the district at present for the recover of phosphate rock from the crude ores or matrix, is not a complicated process. Flow sheets of the several companies are similar, although the equipment varies with the preferences of the individual operators. For disintegrating the matrix log washers are favored, although revolving drums equipped with flights to break up lumps of clay are also used. Fine sand is removed by screening. Vibrating screens have become well established in the district, although stationary flat screens and trammels are also employed.The writer acknowledges with appreciation the cooperation of the phosphate companies in the land-pebble district; suggestions and criticism by Will. H. Coghill, supervising engineer, Ore Dressing Section of the Bureau of Mines; and the laboratory assistance of J. O. Davie, J. W. Pamplin, and E. Roca, cooperative fellows of the University of Alabama.Losses in the Finer SizesOf the phosphate that is not recovered by present washing methods the greater portion is in the finer sizes. In these sizes the phosphate grains are accompanied by grains of sand - largely quartz - of the same size, and recovery of these phosphate grains as a commercial product is not possible by simple washing methods. Phosphate recoveries approaching complete extraction can only be effecte by applying metallurgical processes, either mechanical or chemical. As yet, most of these processes have not advanced much beyond the laboratory or perhaps the pilot-plant stage. Such processes may have some application to the beneficiation of phosphatic ores or washer rejects, but a discussion of them is not within the scope of this paper."

Apr 1, 1929

By Michael J. Pazuchanics, Thomas J. Fisher, John J. Sammarco, Jeffrey H. Welsh

This report (An Introduction to Safety) is the first in a nine-part series of recommendations addressing the functional safety of processor-controlled mining equipment. It is part of a risk-based system safety process encompassing hardware, software, humans, and the operating environment for the equipment's life cycle. Figure 1 shows a safety framework containing these recommendations. The reports in this series address the various life cycle stages of inception, design, approval and certification, commissioning, operation, maintenance, and decommissioning. These recommendations were developed as a joint project between the National Institute for Occupational Safety and Health and the Mine Safety and Health Administration. They are intended for use by mining companies, original equipment manufacturers, and aftermarket suppliers to these mining companies. Users of these reports are expected to consider the set in total during the design cycle. • 1.0 Safety Introduction.—This is an introductory report for the general mining industry. It provides basic system/software safety concepts, discusses the need for mining to address the functional safety of programmable electronics, and includes the benefits of implementing a system/software safety program. • 2.1 System Safety and 2.2 Software Safety.—These reports draw heavily from International Electrotechnical Commission (IEC) standard 61508 and other recognized standards. The scope is "surface and underground safety mining systems employing embedded, networked, and non-networked programmable electronics." System safety seeks to design safety into all phases of the entire system. Software is a subsystem; thus, software safety is a part of the system's safety. • 3.0 Safety File.—This report contains the documentation that demonstrates the level of safety built into the system and identifies limitations for the system’s use and operation. In essence, it is a "proof of safety" that the system and its operation meets the appropriate level of safety for the intended application. It starts from the beginning of the design, is maintained during the full life cycle of the system, and provides administrative support for the safety program of the full system. [ ]

Jan 4, 2001

Objective To reduce equipment operator exposure to respirable dust in enclosed cabs by examining the effectiveness of retrofitting air pressurization and filtration systems on existing cabs. Background Many types of heavy equipment are used in mining, construction, and agriculture. Most have enclosed cabs to protect the equipment operator from excessive dust and noise exposure. When the equipment is new, controls are normally implemented into the cab to keep these exposures at acceptable levels. However, as this equipment becomes older, many components of the enclosure deteriorate, such as gaskets and seals. This causes the effectiveness of the enclosed cab to be greatly reduced. Once this occurs, the equipment operator's dust exposure can increase to hazardous levels. In surface mining operations, elevated exposures to crystalline silica have caused an excessive incidence of silicosis. Approach A cooperative research study with a mining operation and a cab filtration company was conducted to evaluate the effectiveness of retrofitting an older surface drill with two controls to lower the drill operator's respirable dust exposure. These two controls were: (1) A good air filtering and pressurization system to ensure that clean air was delivered into the enclosed cab. Ideally, the incoming air filter should be 99% efficient in removing particles with an aero- dynamic diameter of 0.3 pm or greater from the airflow. (2) Sufficiently sealing the cab to develop a positive static pres- sure and ensure that dust was not leaking into the cab. This was done by plugging all holes and cracks and maintaining good gaskets and seals. To prevent wind from forcing contaminated air through holes in the cab, the cab's static pressure must be greater than the wind's velocity pressure. During the course of this research, it was found that a floor heater fan used in the drill during the winter months greatly increased the operator’s Respirable dust exposure. Problem Identification Four days of background dust levels were measured as a baseline for this research. These baseline measurements were taken in May 2000 when air temperatures ranged from 60° to 70° F. When this was completed, the two controls were implemented. The first control was to install an improved air filtering and pressurization system on the enclosed cab. This was composed of a two-stage prefilter, a blower, then the respirator-medium secondary filter. Since the secondary filter was on the positive side of the fan, all air delivered into the enclosed cab had to pass through this secondary filter. After the filtering system was installed, the cab was pressurized to a static pressure of0.01 inches of water (w.g.), which is still very minimal. The second control was to seal the cab. New door gaskets were installed, and all cracks and holes in the shell of the enclosure were plugged. This increased the cab pressurization to approximately 0.1 inches w.g.

Mar 1, 2001

Homans [1950] offered a working definition of group that is useful for this research: "We mean by a group a number of persons who communicate with one another often over a span of time, and who are few enough so that each person is able to communicate with all the others, not at secondhand, through other people, but face-to-face." This chapter begins with a discussion of the group concept in reference to the hypothesized escape groups mentioned earlier. It then moves to an examination of analysis techniques used by the authors. Finally, the subjects themselves are profiled according to their demographic characteristics. The Nature of Groups Warriner [1956] took a realist approach to understanding groups: "(1) the group is just as real as the person, but (2) both are abstract, analytical units, not concrete entities, and (3) the group is understandable and explicable solely in terms of distinctly social processes and factors, not by reference to individual psychology." Warriner's realist position merely holds that "group" occupies a different domain in which it is no more or less concrete than "person." At this group level the unit of analysis will be those relations that indicate social rather than individual behavior. It is possible to investigate these group properties empirically-if a researcher avoids confusing conceptual entities with concrete ones. Most people seem to accept that group attributes must somehow be inferred, but think personal attributes will be directly manifested, requiring little or no interpretation [Snizek 1979]. In other words, nobody would equate physical components of an underground working section with the actual work group, yet social scientists (as well as laypeople) very often confuse real individuals with notions of the person. In actuality, neither groups nor persons are directly disclosed to the senses; both are inferred by experience and observation. One can "see" a group just as clearly as one can "see" a person, given the proper perspective from which to do so. It is necessary, in developing this perspective, to begin with a sound definition of the thing being examined. Besides communication, or more generally, social interaction, Homans [1950] included three other components of group makeup. "Sentiment" is characterized as the feelings people tend to form about one another when they interact often. These feelings include not only friendliness and dislike, but attitudes such as approval or disapproval. A "norm" is an idea, held in common by group members, that specifies how people ought to behave in given circumstances. In lay terms, norms are simply those informal rules individuals abide by in order to get along together in social situations. Finally, "activity" refers to those things persons do with others. In work groups, as an example, many of the activities are cooperative and goal-directed.

Jan 1, 2000