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By T. R. Taubert, D. H. Carlson, J. H. Johnson

The U.S. Bureau of Mines and Michigan Technological University (MTU) are collaborating to develop an apparatus for measuring diesel tailpipe emissions in underground mines. A tailpipe emissions measurement apparatus (EMA) is described that dilutes diesel exhaust and measures the concentrations of diesel particulate matter (DPM), CO, CO, NO, and NO, at known dilution ratios. The EMA was evaluated by side-by-side comparison of its measurements with those by laboratory- grade instruments. Concentrations of CO and CO, measured by the EMA were usually within + 14 pct of concentrations measured by laboratory-grade instruments for CO and 220 pct for CO,. EMA- measured DPM concentrations were, on average, 29 pct lower than those measured by laboratory-grade instruments, with the differences being fairly consistent. The CO and CO, differences are related to the method of calculating the EMA's dilution ratio, and the difference in DPM concentrations is attributed to thermophoretic and/or condensation losses related to the EMA's unheated sample probe. Preliminary analysis of data obtained with a heated sampling probe and modifications in the sampling procedures have indicated reduced variability in DPM and in the calculated dilution ratios.

Jan 1, 1992

By Robert R. Stein, Roy C. Bartholomae, William W. Aljoe

This Bureau of Mines report describes in detail the design and operation of a test apparatus for measuring the sound power levels of drills used by the mining industry. The two major components of the test apparatus are a computer-controlled automated drill test fixture (ADTF) and a large (45,000-ft3) reverberation chamber that houses the ADTF. Design specifications and performance capabilities of the ADTF and the reverberation room are given. Initial test results for three types of drills--a pneumatic percussion drill, a hydraulic percussion drill, and a pneumatic rotary drill--are given to illustrate the types of experiments that can be conducted with the test appartus.

By William C. McBee

Prompted by forecasts of a sulfur oversupply, the Bureau of Mines, U.S. Department of the Interior, is conducting research on potentially large-scale uses of this commodity to extend or replace such construction materials as asphalt, cement, and mineral aggregates. Through these efforts, paving materials have been developed in which sulfur replaces up to 50 pct of the asphalt normally present and which can be prepared and placed with existing mixing and paving equipment. Laboratory properties and design methods for this direct mixing process are described along with properties obtained on small-and large-scale field demonstration projects. These properties are compared with those obtained from control materials prepared without sulfur additions. Monitoring for toxic gases during laboratory and commercial mixing and paving operations is discussed also.

Jan 1, 1978

By L. Prosser, A. Iannacchione, G. Esterhuizen

The potential for roof falls in underground mines remains a clear and present danger for mine workers. An investigation of ground conditions in nearly 50% of the nation’s underground stone mines found that the state of roof stability is primarily determined in a limited and subjective manner. These large opening mines, with roof heights typically of 7 m or more, make physical observation difficult. Although some mines use monitoring techniques to gain additional information on roof stability, this practice is usually short-term and localized to address ground conditions in a particular section or part of the mine. A methodology to assess the risk for a roof fall is proposed in a preliminary fashion based on engineering judgment acquired from extensive underground stone mine experience and examination of related literature. The proposed method utilizes an observational technique to identify the risk of roof falls in three categories. Case study scenarios provide a realistic picture of model implementation. Providing the mine level decision maker with an accurate assessment tool to ascertain the level of risk related to ground conditions is expected to reduce mine worker injuries and fatalities. Moreover, the presences of danger can be overcome with a clear picture of quantified ground conditions.

Develop an inexpensive, reliable means of quickly detecting and locating trapped miners in underground coal mines, particularly after a mine accident. The Limitations Although the Bureau of Mines has performed extensive research on the use of electromagnetics for locating trapped miners, much of its research trends toward the development of long-range systems designed to locate an underground transmitter from the surface. Such location systems are beneficial; however, there are several limitations regarding their use. Two limitations are weight and cost of the equipment. Most long-range detection systems would be too heavy and cumbersome to be accepted by miners as part of their daily protective equipment. Since such long-range detection systems are usually expensive, it would not be economically feasible for every miner to be provided with a system.

Jan 1, 1984

By C. H. Elder, Fred N. Kissell, S. D. Maksimovic

The Bureau of Mines evaluated the hydraulic stimulation of a gob-degasification borehole to determine if this procedure would aid in degasifying a longwall panel. The stimulated borehole did not degasify the longwall panel as expected either before or after mining of the panel started. It reduced the underground methane emission only 11 pct, considerably less than the reductions effected by two unstimulated boreholes in the same panel. Some probable reasons for the reduced methane flow from the hydraulically stimulated borehole are very low reservoir gas pressure, location of hydraulically stimulated zones within the grouted casing, a casing break caused by lateral shifting, possible vertical movement of rock strata during caving, grouting of a 4-inch pipe blocking three stimulated zones, plasticity of shales, and possible hole damage by swelling of water-sensitive minerals. The borehole was also located between two second-mined areas, which may have allowed partial degasification of the overburden and the coalbed in advance of mining. Finally, a period of 3 months is probably not long enough for the borehole to degasify the overburden before mining.

Jan 1, 1977

By D. R. Tesarik, M. K. Larson, J. P. Dunford, E. G. Zahl

Western coal mines are operating under increasingly challenging ground conditions. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are cooperating with mines to evaluate how these conditions affect mine opening stability and related miner safety. A system was developed to monitor rock and coal stresses during mining of an entire longwall panel. The system was designed to generate data in near real time to evaluate rock behavior in roof strata and the onset of hazardous conditions as overburden stress was redistributed over working entries during gob formation. Computer simulations and in-mine evaluations were used to optimize instrument placement. A prototype packer assembly was designed and tested for installing sensitive instruments in a mine roof. This paper provides background information on the stress monitoring concept and focuses on the development of instrument placement techniques and the prototype packer assembly.

By Thomas M. Barczak

The success of longwall mining can largely be traced to the development of powered roof support systems. The most significant improvement in powered support design has been the shield support, which improved kinematic stability and promoted the application of longwall mining in difficult-to- control caving conditions where chock and frame supports were inadequate. The most obvious trend in shield design has been an increase in shield size and capacity. This U.S. Bureau of Mines report examines shield design and operation practices and their consequences for the utilization of high-capacity shield support systems. An optimization goal is to minimize support loading by selecting an active shield setting force that is compatible with strata behavior and shield loading characteristics. Shield stiffness is an important design parameter that is often overlooked. A consequence of increasing shield capacity by incorporating larger diameter leg cylinders is a proportional increase in shield stiffness. Setting forces have also increased in direct proportion to the increase in shield capacity. The increased stiffness and higher setting force cause the available capacity to be consumed more quickly, severely limiting the ability of high-capacity supports to last longer and provide reserve capacity for difficult mining conditions.

Jan 1, 1992

Predict the cumulative hydrologic impact of mining on the environment. Approach A comprehensive set of computer models has been developed to predict the impact of mining on ground water. Mine inflows, drawdowns in aquifers, and ground water quality can be predicted. How It Works The Prickett-Lonnquist finite-difference groundwater model was specially modified for the hydrologic problems of mining. This model, developed at the Illinois Water Survey in the 1960's,

Jan 1, 1982

By W. W. Adams

During the calendar year 1927 the United States Bureau f Mines conducted, for the third consecutive year, a safety contest among more than 250 mines and quarries. Aside from its underlying purpose to promote safety, the object of the contest was to learn which mine or quarry had completed the year's work with the smallest proportionate loss of time from accidents to its employees. Competing companies were grouped into five classes, namely, anthracite mines, bituminous teal mines, metal mines, nonmetallic mineral mines, and quarries and open-pit mines. To the winning company in each group was awarded the bronze trophy "Sentinels of Safety," the gift of The Explosives Engineer magazine. The winner in each group was the mine or quarry whose record showed the smallest loss of time from accidents in proportion to the total amount of time worked by 411 employees. This proportion is designated the "accident-severity"3 rate; it indicates the number of days of disability resulting from personal injuries per thousand man-hours of work performed by all employees. Each company's standing was determined by the Bureau of Mines from detailed records furnished by the contestants. Records of the leading companies were made known to a committee of seven men well known to the mining industry but not connected with the Bureau of Mines. This committee selected the winning companies in accordance with rules governing the Competition. According to the contest rules, the competition for the trophy was restricted to mines employing at least 50 men underground and to quarries and open-pit mines employing at least 25 men in the pit. As several plants fell below these figures during the year, their records could not be considered in connection with the award of the trophy. Figures covering these plants are, however, included in the attached tables.

Jan 1, 1928

By T. G. Carnahan

The Federal Bureau of Mines investigated, on a laboratory scale, a technique for recovery of silver from pregnant solutions generated in the hydro-metallurgical treatment of complex base-metal sulfide concentrates with oxidizing chloride media. This technique provides a means for recovery and simplified reduction of accessory silver to metal from chloride solutions. The method consists of adding NaI or KI to the solution to precipitate AgI, which is then contacted with Na2S to produce Ag2S and to regenerate the iodide salt solution. Silver recoveries range from 99 pct with 20 pct excess iodide precipitant, to 92 pct when the theoretical stoichiometric amount of precipitant is employed. The Ag2S product can be reduced to silver metal by contact with aluminum chips in NaOH solution followed by purification with conventional fire refining techniques.

Jan 1, 1980

By R. C. Wang, W. M. McKewan

The behaviour of wire ropes used in mine hoisting is not well understood. In an effort to improve this understanding, the structure of round-strand wire ropes was analysed. This report provides a generalised mathematical model that completely describes the geometry of the wires. It consists of two sets of vector equations and is valid for any round-strand wire rope. One set of equations is used to trace the paths of wires that have the form of a single helix. The other is used for the paths of double helical wires. The specific model for a 33-mm 6x1 9 Seale, IWRC, right regular lay wire rope was presented as an example. The paths and the geometric properties of the wires which include the path length per lay of strand, the curvature, and the torsion were determined from this model. In future work, the model could be used to conduct stress analysis for the wires in the deformed rope at a given rope strain and also to study the effect of wear and breaking of wires on strength loss for the various round-strand wire ropes used in mine hoisting.

By R. D. Saltsman

Under contract with the Federal Bureau of Mines, Bituminous Coal Research, Inc., performed a statistical study to find less expensive and time-consuming methods of monitoring the noncombustible content of coal mine dust. Calculations based on thermodynamic considerations verified the reasonableness of Federal rock-dusting requirements. The results of extensive sampling in southwestern Pennsylvania mines indicated that, at the 95-percent confidence level, the present system of sampling at 200-foot intervals may be replaced by sampling at 500-foot intervals, and that a 1-inch scoop floor sampler may replace the standard 6-inch scoop for floor sampling. Further field testing is recommended.

Jan 1, 1975

Provide a means for reliable in situ stress change measurements in soft, friable geologic materials under high stress. Background Effective mine design requires a knowledge of changes in rock stress generated by a mining operation. In situ stress measurement can provide a means of obtaining this knowledge from an active mine for the ultimate purpose of design verification and analysis. The Bureau of Mines has designed and tested a device for measuring changes in rock stress-the borehole platened flatjack (BPF). It has found application in investigating stress anomalies due to geologic structures, stress concentrations from multiple seam interaction, and stress abutments from pillar retreat and longwall mining.

Jan 1, 1990

By N. T. Lowe, R. E. Miller

When two pieces of heavy equipment interact, jolting and jarring can occur. During haulage truck loading for example, there is a chance that the operator of one or both pieces of the equipment will experience jolting and jarring. Additionally, a jolt can occur when an off highway equipment operator drives over a road defect or inadvertently strikes a berm. Aside from the operators, there is seldom anyone else that witnesses the interaction and can accurately describe the extent of the jolting. This makes it difficult for health and safety managers to address jolting and jarring. The devices and software described in this paper constitute a method for installing “black boxes” called Shox Boxes onboard equipment that already have a GPS system onboard. The resulting configuration provides an objective assessment of jolting and a chance to determine the root causes of it. The Shox Box system reviews data in real time, onboard the vehicles, 24 hrs a day, and sends pertinent information via radio to a central database. The data generated shows whether jolts are above or below a supervisor defined target value for the equipment and the tasks being performed. This allows health and safety personnel to demonstrate safe operation of heavy equipment and recommend proactive actions to maintain jolting within a reasonable range.

By Linda L. Chasko, Charles P. Lazzara, Ronald S. Conti, William J. Wiehagen

Fire has long been a concern for underground mine workers. A mine fire can occur at any time and can result in a partial or total evacuation of mine personnel and the loss of lives. Fires can grow rapidly. Time is the critical element. Prompt detection, timely and accurate warnings to those potentially affected, and a proficient response by underground miners can have a tremendous impact on the social and economic consequence of a small underground fire. Fire preparedness and response have components of technology and people. These components can work synergistically to reduce the time it takes to bring the system back in balance. This report deals with the preparedness of miners to respond to underground mine fires. It is intended to aid the mining industry in understanding the various roles of emergency responders and the training techniques used to increase their skill levels. The report also presents a technology overview to assist in effective response to mine fires.

By Robert L. Chufo

This paper describes a general purpose imaging technology developed by the U.S. Bureau of Mines (USBM) that, when fully implemented, will solve the general problem of "seeing into the earth." A first generation radar coal thickness sensor, the RCTS-1, has been developed and field-tested in both underground and highwall mines. The noncontacting electromagnetic technique uses spatial modulation created by moving a simple sensor antenna in a direction along each axes to be measured while the complex reflection coefficient is measured at multiple frequencies over a two-to-one bandwidth. The antenna motion imparts spatial modulation to the data that enables signal processing to solve the problems of media, target and antenna dispersion. Knowledge of the dielectric constant of the media is not necessary because the electrical properties of the media are determined automatically along with the distance to the target and thickness of each layer of the target. The sensor was developed as a navigation guidance sensor to accurately detect the coal/noncoal interface required for the USBM computer-assisted mining machine program. Other mining applications include the location of rock fractures, water-filled voids, and abandoned gas wells. These hazards can be detected in advance of the mining operation. This initiating technology is being expanded into a full threedimensional (3-D) imaging system that will have applications in both the underground and surface environment.

By M. A. Trevits, S. W. Lambert

In this Bureau of Mines investigation, production was monitored for 1 year at over 30 coalbed gas-drainage boreholes located in Alabama, Pennsylvania, and West Virginia. Results indicate that the quality of data gathered from such wells can be improved greatly if potential problems are anticipated and prevented in the early stages of well production. Major water-monitoring problems include solids buildup, freezing, the presence of gas in surface waterlines, and improper pumping interval settings. Such problems may be avoided by incorporating in the original well design waterline filters, sand screens, separator tanks, and systems to automatically control pumping intervals. Problems related to measurement of coalbed gas flow include large quantities of water vapor contained in the gas, especially during winter months; freezing and subsequent obstruction of flow; sudden, uncontrolled release of gas pressure; and solids buildup in metering equipment. The installation of commercially available items, such as filters, separators, and insulation, and the thoughtful application of a basic knowledge of coalbed gas reservoir characteristics will prevent most production-monitoring problems.

Jan 1, 1978

As technology evolves, accidents may occur because human-system interactions were not considered adequately in the process. A systematic methodology can be used to evaluate the causes of mishaps and to develop recommendations that will enhance safety. A recent trend observed in underground coal mining is used to illustrate this principle because an underground mine is a dynamic work environment. Mining is characterized not only by frequent geologic changes but by technological evolution that can seriously degrade human performance and compromise worker health and safety The case exemplified in this paper involves implementation of remotely controlled equipment for extended cut mining. Extended cut mining technology evolved with minimal ergonomic consideration even though the change from on¬board to remote machine operation dramatically modified the role of the human component. In response to concern that system interactions should be examined more closely. a methodology was developed to identify hazards.

Jan 1, 1998

By M. B. Cooke

 An analytical method for the determination of the gum-forming material in gasoline has been developed by the Bureau of Mines, during a study now in progress to determine the best rays for elimination of such constituents from gasoline. This method is similar in principle to that previously described by Smith and Cooke, which involved evaporation of e semple of gasoline in a small glass dish. The evaporation was started on an actively boiling steam bath and completed in an air oven at 105°C. In the improved method described below, the steam bath has been replaced by a steam heated oven in which an inert atmosphere is maintained. Air is ex- cluded from the oven, consequently the precision of the determination is increased. Furthermore, evaporating dishes different from those previously described may be used.

May 1, 1925