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Groundwater Flow Model (GWFM) Development, Midnite Mine, Wellpinit, Washington

Description: This Report of Investigations (RI) is one of several describing work that has been completed by the U.S. Bureau of Mines at the Midnite uranium mine, Wellpinit, WA. Dean (in preparation) describes the entire project history. Four diskettes containing three archives compressed using WINZIP (or PKZIP) accompany the current RI. The ultimate purpose of this research effort was to develop a groundwater flow model (GWFM) for the Midnite Mine that can be utilized by the contractor preparing the Environmental Impact Statement (EIS) and by other interested parties. The objectives of this study were to (1) develop a shell model of the geology at the site, (2) develop the basis for a GWFM that will meet criteria described elsewhere in this RI and that can be updated with new information generated during the EIS process, and (3) present the results of two steady-state simulations of groundwater flow within the bedrock units. The current GWFM generates nonunique solutions because flow data for the bedrock units currently do not exist. However, the model provides useful results with respect to direction of flow. More data are required to model the bedrock aquifer system accurately. Volmnetric flow rates of the bedrock units should be measured or estimated. Measurements obtained from one or two drains completed in the bedrock in the southern portion of the site should yield these values.
Date: 1996
Creator: Kirschner, Frederick E.
Partner: UNT Libraries Government Documents Department

U.S. Bureau of Mines Final Report : Midnite Mine Water Treatment Studies

Description: The U.S. Bureau of Mines reviewed and evaluated options for treatment of the approximately 500 million gallons of contaminated water in flooded pits at the Midnite Mine on the Spokane Indian Reservation. While current lime treatment produces discharge quality water, the resultant sludges are radioactive, presenting a disposal problem. Of the 24 commercial processes and seven emerging technologies evaluated, none demonstrated a significant advantage over ion exchange using a strong base anion exchange resin in either laboratory or field tests. Uranium was lowered from 22 ppm to 0.2 ppb in treated water. Radium was lowered from 44 pCi/L to <1 pCi/L using a modified precipitation with BaCl2 . The natural zeolite, clinoptilolite, lowered radium to 6-8 pCi/L when used as an ion exchanger.
Date: 1996
Creator: Schultze, L. E.; Nilsen, D. N.; Isaacson, A. E. & Lahoda, E. J.
Partner: UNT Libraries Government Documents Department

Hydraulic Characterization of Midnite Mine, Wellpinit, Washington: Summary of 1994 Field Season

Description: The Midnite Mine is an inactive uranium mine on the Spokane Indian Reservation in Washington State. Oxidation of sulfide-containing minerals, primarily pyrite, produces acidic water. Uranium and other radioactive constituents are chemically leached and dissolved in ground and surface waters. The U.S. Bureau of Mines (USBM) has worked closely with the Bureau of Indian Affairs, the Bureau of Land Management, and the Spokane Tribe of Indians to address data needs for remediation of the disturbed area. As part of this effort, USBM personnel initiated research to determine water quality and define groundwater flow characteristics. Preliminary results of hydraulic stress tests performed in the bedrock at the site are described. Slug tests and pumping tests were conducted using preexisting USBM monitoring wells. Slug test results were used to generate hydraulic conductivity estimates for fractured and unfractured intrusives. The pumping tests demonstrated varying degrees of spatial continuity. Hydraulically continuous fractured zones along north-south planes were demonstrated in two cases for distances of 90 and 116 m (300 and 380 ft). The short-term pumping tests provided no evidence of east-west hydraulic continuity in fractured zones.
Date: 1996
Creator: Williams, Barbara C. & Riley, John A.
Partner: UNT Libraries Government Documents Department

Midnite Mine Summary Report

Description: The Midni'e Mine is an inactive, hard-rock uranium mine in Stevens County, WA. Oxidation of sulfide-containing minerals in the ore body produces large quantities of acidic water. The U.S. Bureau of Mines was directed by Congress in Fiscal Year 1994 to perform technological research on the treatment of radioactive water and disposal of treatment residues at the Midnite Mine and en overall site reclamation. This Report of Investigations summarizes the studies that were completed on: 1) treatment alternatives for uranium contaminated acid mine drainage, and 2) overall site reclamation, including: ground water flowpaths in the bedrock, radiation, and waste rock reactivity. As an aid to site reclamation, a Geographic Information System database was also produced that contains available current and historic data and information on the Midnite Mine. This report explains the scope of the Bureau's study and summarizes the results of its investigations.
Date: 1996
Creator: Dean, N. E.; Boldt, C. M. K.; Schultze, L. E.; Nilsen, D. N.; Isaacson, A. E.; Williams, B. C. et al.
Partner: UNT Libraries Government Documents Department

Dust Sources and Controls for Multiple-Machine Longwall Faces

Description: Abstract: Longwall mining in lower seam heights may necessitate the use of single-drum shearers to overcome size constraints associated with standard double-drum shearers. To avoid the operational problem of clearance in the tailgate entry with one single-drum shearer, two single-drum machines can be operated on the same face, with each shearer responsible for mining a predefined portion of the face. However, utilization of two shearers on the same face necessitates the positioning of one shearer operator and a jacksetter in the return air of the upwind shearer, thus complicating respirable dust control on the longwall. In an effort to evaluate the unique dust control problems associated with this type of mining, the U.S. Bureau of Mines conducted dust surveys on two multiple-machine longwall operations. Sampling was done to quantify major sources of respirable dust and to identify potential solutions to problem areas. Sampling results indicate that the cutting sequences utilized on multiple-machine faces may have to be designed to minimize dust exposure, as opposed to optimizing productivity or facilitating operational requirements. Also, state-of-the-art dust control techniques typically found on double-drum shearer longwalls must be employed to help minimize the exposure of all face personnel to traditional dust sources.
Date: 1995
Creator: Colinet, Jay F. & Spencer, Ellsworth R.
Partner: UNT Libraries Government Documents Department

Numerical Modeling Analysis of Stress Transfer Modification Concepts for Deep Longwall Mines

Description: Abstract: This U. S. Bureau of Mines (USBM) report evaluates three stress-transfermodification concepts for their potential in reducing longwall gate road stresses and closures. In each of the three concepts - packwalling, gob infilling, and entry filling - support structures are constructed on the headgate side of the panel parallel with or inby the face line. When the headgate becomes the tailgate of the adjacent panel, these structures are in place to accept stresses transferred from the mined-out panel. Using the USBM nonlinear boundary-element program MULSIM/NL, baseline models of typical longwall stress transfer behavior were developed for both intermediate depth and deep mining conditions. These models were verified by comparing model results with field measurements and observations. The stresstransfer-modification concepts were then incorporated into the deep baseline model to quantify the effects of each concept on tailgate closure. Modeling results indicated that entry filling is the most effective concept in reducing tailgate escapeway closure. Using only 18 m3 of a weak fill per meter of face advance (7.3 yd3 per ft of face advance), tailgate escapeway closure was reduced by 33%. By improving the quality of the fill, similar results were achieved using 50% less volume.
Date: 1995
Creator: Vandergrift, Thomas L. & Jude, Charles V.
Partner: UNT Libraries Government Documents Department

Well-Point Containment of Impoundment Leakage

Description: Research was conducted to evaluate the effectiveness of a well-point dewatering system in conjunction with a french drain to intercept waste impoundment leakage while reducing the volume of waste water requiring treatment. A well-point dewatering system composed of 585 production wells was installed around the perimeter of a leaking impoundment that previously used only a french-drain system for leakage control. The placement of the well-point system was designed to intercept and remove the leakage from the groundwater before the contaminant reached the french drain. Groundwater monitoring at this site revealed that after a period of approximately 40 days the well-point dewatering system had stabilized and effectively prevented the further spread of contamination to the french drain.
Date: 1995
Creator: Smith, C. W.
Partner: UNT Libraries Government Documents Department

Bending Fatigue Tests on Flattened Strand Wire Rope at High Working Loads

Description: Abstract: The U.S. Bureau of Mines established a wire rope research laboratory to examine the factors that affect the safety and the useful life of wire rope. In the most recent work, two 32-mm 6x27H flattened strand ropes were degraded on a bending fatigue machine. The two tests were run at constant loads of 285 and 347 kN or safety factors of 2.5 and 2. Nondestructive and tensile strength tests were performed on samples of the ropes to determine the relationship between rope deterioration and rope breaking strength. Neither the area loss nor the number of broken wires measured from nondestructive tests could be used as clear indicators of the loss of strength. However, it was found from the tensile tests for both rope specimens that the strength loss was associated with the reduction of breaking strain. This suggests that measuring the strain of many short sections of a rope in the elastic region may locate the high stress sections and thus determine the condition of the rope.
Date: 1995
Creator: Wang, Richard C. & Shapiro, David E.
Partner: UNT Libraries Government Documents Department

Human Factors Analysis of Roof Bolting Hazards in Underground Coal Mines

Description: Abstract: The U.S. Bureau of Mines conducted a human factors analysis of hazards associated with roof bolting activities in underground coal mines. Emphasis was placed on hazards related to the movement of the drill-head boom or mast of a roof bolting machine. The objective was to identify hazards and recommend solutions. The data-collection effort consisted of analysis of U.S. Mine Safety and Health Administration accident data; visits to underground mines and interviews with experienced roof bolting machine operators; discussions with roof bolting machine manufacturers; interviews with workers injured while performing roof bolting tasks; and reviews of research on roof bolting safety. A set of recommendations to increase the safety of roof bolting operations was developed. In particular, the following list of recommendations was presented in ranking order: (1) use an interlock device to cut off power to controls when an operator is out of position,,(2) place fixed barriers at pinch points, (3) provide appropriate control guarding, (4) reduce fast-feed speed, (5) use automatic cutoff switches at pinch points, (6) redesign control bank to conform to accepted ergonomic principles, and (7) use resin insertion tools and resin cartridge retainers.
Date: 1995
Creator: Turin, Fred C.
Partner: UNT Libraries Government Documents Department

Electrochemical Reduction of Titanium in Nonaqueous Solvents

Description: Abstract: Electrorefining of Ti in nonaqueous solvents has been studied by the U.S. Bureau of Mines as a method for recycling impure scrap Ti. Electrochemical behavior of Ti species was investigated using cyclic voltammetry. Research results showed that Ti metal can be dissolved in polar solvents such as dimethylformamide or dimethyl sulfoxide. However, deposition of Ti from these solvents was not successful. Several solvent systems were investigated for electrodepos.tion of Ti but no deposits were obtained. Reduction of Ti' complexes to Ti" proved to be straightforward, but reduction to lower oxidation states could not be confirmed. In dimethylformamide solutions, cyclic voltammetry results demonstrated the reduction of Ti to an oxidation state of less than three, but no Ti metal was identified. In dimethyl sulfoxide solutions containing LiCl, it was possible to deposit Li metal. After adding Ti salts to the solution, electrolysis quickly passivated the electrode. Deposition of Ti was also investigated in solutions of dimethoxyethane and propylene carbonate but, again, no reduction of Ti to oxidation states of less than three occurred. Therefore, the prospects for a nonaqueous electrorefining system for Ti metal do not appear promising.
Date: 1995
Creator: Sibrell, P. L.
Partner: UNT Libraries Government Documents Department

The Reduction of Airborne Dust Generated by Roof Bolt Drill Bits Through the Use of Water

Description: Abstract: In the vast majority of American coal mines, roof bolt holes are drilled dry, mainly because of mine operator concern with the spent water creating adverse working conditions. Wet drilling, however, can increase drilling rates and the effective lifetime of the drill bits used. This study, carried out as part of an ongoing cooperative research program between the U.S. Bureau of Mines and the University of Missouri-Rolla, shows that the large volumes of water conventionally used in wet drilling are not necessary, and the performance benefits from wet drilling can be achieved with total volume flows on the order of 0.4 L per hole. This conclusion is validated based on the measured respirable dust generated in drilling Berea sandstone. The results are confirmed using a variety of bit shapes, which are also shown to have a significant effect on penetration rate.
Date: 1995
Creator: Sundae, Laxman S.; Summers, David A.; Wright, Douglas & Cantrell, Bruce K.
Partner: UNT Libraries Government Documents Department

Timing and Duration of Subsidence Due to Longwall Mining

Description: Subsidence data gathered by the U.S. Bureau of Mines over a series of longwall panels in the Pittsburgh Coalbed were studied to obtain insight as to the role of time in the subsidence process. It was found that subsidence began essentially with undermining and was completed within 1 year. The progress of the subsidence was dependent upon location above the panel. Subsidence in the central area of the subsidence trough, where subsidence is the greatest, was about 90 pct complete by the time the face had progressed a distance equal to one overburden thickness beyond a particular surface point. For a point over the rib of the longwall panel, the subsidence was only about 60 pct complete at this time. Data from three other sites in the northern Appalachian Coal Basin were analyzed to determine if an anomaly or the true characteristics of the subsidence process had been observed. All sites behaved similarly in the central portion of the subsidence trough. However, the subsidence of points over and adjacent to the ribs of the longwall panels was site specific. The fact that movement across the width of the panel was not uniform should be taken into account in assessing damages or the potential for damages resulting from mining-induced subsidence.
Date: 1995
Creator: Jeran, Paul W. & Trevits, Michael A.
Partner: UNT Libraries Government Documents Department

A Profile of Workers' Experiences and Preparedness in Responding to Underground Mine Fires

Description: The purpose of this study was to determine mine workers' state of fire-fighting preparedness and the technology being used to detect and respond to underground coal mine fires. To investigate this problem, 214 underground coal miners were interviewed by U.S. Bureau of Mines researchers. Frequency distributions of workers' responses are presented in this report, along with segments of narrative accounts, to profile miners' fire-fighting capabilities. The data indicated that much variability exists from mine to mine and that there are several important changes operators may undertake in order to make miners better prepared to deal with fire underground: select appropriate sensors, establish and test a warning and communication protocol, construct a system capable of delivering hundreds of gallons of water per minute for sustained periods, institute formal fire preparedness audits, develop case studies of events that occur at an operation to use as teaching and assessment tools, and provide structured practice that can be incorporated into fire drills.
Date: 1996
Creator: Vaught, Charles; Fotta, Barbara; Wiehagen, J.; Conti, Ronald S. & Fowkes, Richard S.
Partner: UNT Libraries Government Documents Department

Longwall Gate Road Stability in a Steeply Pitching Thick Coal Seam with a Weak Roof

Description: The U.S. Bureau of Mines (USBM) conducted ground pressure analysis of a wide abutment-type chain pillar in a two-entry gate road of a Western U.S. coal mine with an extremely weak immediate roof. About 15 m of fragile, low-strength mudstone lies between the seam and the lowest competent roof member. Three- and two-entry gate road designs with several pillar sizes and various secondary support systems have been employed to improve tailgate-entry stability, with varying results. This report discusses gate road layout and performance and secondary support effectiveness. The results of the pillar pressure study are compared to pillar loading predicted by a widely used pillar design method and to similar studies in other mines. A stability evaluation of the most recent longwall headgate, using the USBM Analysis of Longwall Pillar Stability (ALPS) method, indicates marginal stability in first-panel mining and instability in second-panel mining. The ALPS method and the USBM Coal Mine Roof Rating system are used to evaluate tailgate-mining stability of the previous gate roads and to determine pillar and entry width and top coal thickness criteria for tailgate stability in future panels.
Date: 1995
Creator: Barron, Lance R. & DeMarco, Matthew J.
Partner: UNT Libraries Government Documents Department

Reducing Respirable Dust Levels During Bag Conveying and Stacking Using Bag and Belt Cleaner Device

Description: Abstract: The U.S. Bureau of Mines has designed and tested a system called the Bag and Belt (leaner Device (B&BCD) to reduce dust levels in and around the bag conveying and stacking process. The device physically cleans either 22.7 kg (50 lb) or 45.4 kg (100 lb) paper bags by using a combination of brushes and air jets. It is completely self-contained and is kept under negative pressure by a baghouse to ensure that dust and product removed from the bags during cleaning does not flow into the work environment and contaminate workers. The bags travel through the device on a chain conveyor, which permits any product or dust cleaned from the bags to fall into a hopper at the bottom of the device and be recycled back into the process via a screw conveyor. Once exiting the B&BCD, the outside of the bags and the conveyor are essentially product and dust free. The B&BCD was evaluated at two mineral processing plants to determine reductions with the device in use. The results of both field evaluations showed that the amount of product removed from the outside of the bags varied from 77 to 93 pct.
Date: 1995
Creator: Cecala, Andrew B.; Timko, Robert J. & Prokop, Alexander D.
Partner: UNT Libraries Government Documents Department

Reactivity Studies During Drying and Relocation of Lead-Zinc-Gold Tailings: Phase 1 - Preliminary Evaluation and Laboratory Testing

Description: The U.S. Bureau of Reclamation requested U.S. Bureau of Mines (USBM) assistance in developing design data for moving lead-zinc-gold tailings from their current location without disrupting the existing chemically stable conditions. This report presents results of USBM work in determining (1) the minimum required time to air dry the tailings to approximately 20 pct moisture under various drying conditions both in the laboratory and in the field, (2) the degree of oxidation or reduction that occurs during drying, (3) the effect of lime or cement addition before drying, and (4) the likely equilibrium conditions of the dried tailings after deposition at the new location. The limited number of tests performed by the USBM in the available time frame established trends in oxidation levels but did not provide absolute statistical validity of data values. All data from drying and oxidation testing are included in appendices to this report.
Date: 1995
Creator: Froisland, L. J. & Lym, P. B.
Partner: UNT Libraries Government Documents Department

Application of Field Measurements and Computer Modeling to Evaluate Deep Mine Shaft Stability in Northern Idaho

Description: Abstract: Researchers at the U.S. Bureau of Mines have developed personal-computer-based data acquisition, instrumentation, and mine visualization and modeling techniques to evaluate a mine accessway in a deep hard-rock mine in northern Idaho. These techniques were applied to a mine shaft in a large silver mine that has been in operation for many years. A very deep, rectangular, timber-supported shaft extending to depths exceeding 2.3 km (7,500 ft) had been deforming continuously as a result of nearby mining, resulting in operational problems. Preliminary visual observations and rock and support monitoring confirmed that severe diagonal distortion was occurring. Extensive field measurements and data analysis confirmed initial observations, provided insights into the cause of deformation, and defined a general approach to structural modeling. Computer analysis of the problem was initiated by developing a three-dimensional model of the terrain. This represented a volume of rock approximately 80 km3 (40 x 1010 ft) and an area on the surface surrounding the mine 9 km2 (3 square miles). Based on this model, a three-dimensional, finiteelement analysis was conducted to establish boundary conditions for sequentially more detailed two- and three-dimensional submodels of the shaft area. Results from the computer study are being used to develop new approaches to mine design and to provide design guidelines for deep mine accessways subject to severe rock-mass loading conditions.
Date: 1996
Creator: Beus, Michael J.; Orr, T. J. & Whyatt, J. K.
Partner: UNT Libraries Government Documents Department

Radar Positioning System Accuracy Test

Description: Abstract: The U.S. Bureau of Mines conducted research to develop an accurate, real-time, position monitoring and warning system for the vehicles used in surface mining. The product of this research will be technology to reduce accidents and injuries associated with the operation of surface mining haulage equipment. The position monitoring system should reduce accidents related to vehicle position and also increase the efficiency of haulage operations. This research was conducted in preparation for development of an accurate, real-time position monitoring and warning system, which notifies equipment operators when they deviate from a known safe course and are approaching a fixed hazard. A radar positioning system designed for marine applications was evaluated and a series of tests was run to determine the accuracy of the radar positioning system when used in a land vehicle. The radar position determination was compared to surveyed values. Both static and dynamic (moving vehicle) tests were conducted. The static test results were marginal and the dynamic test results were not accurate enough for the position monitoring and warning system. Although a promising technology, the system tested needs to be modified to meet the accuracy requirements of mobile mine equipment.
Date: 1995
Creator: Utt, Walter K.
Partner: UNT Libraries Government Documents Department

Influence of Environmental Factors on Spark Ignition Probability

Description: Abstract: In past years, the U.S. Bureau of Mines has been involved in safety research that could ultimately relate the conditions of spark testing and actual use by estimating the simple ignition probability of a circuit in question. A major problem in estimating this probability is that results show a significant variability, even though gas mixtures and electrical parameters may be closely controlled. Some researchers have suggested that the ambient environmental conditions of the testing may influence the results. A series of tests were conducted using a spark test apparatus to simulate a failing electrical circuit. By independently adjusting the temperature, pressure, or relative humidity of the combustible gas mixture, multiple test environments were examined. At each ignition, a computer recorded the temperature, pressure, and relative humidity of the gas immediately prior to the explosion. These data were then used to establish the effect of the test environment on the ignition probability and to create a mathematical model of the test environment's synergistic effects. The analysis indicated that these effects were not as significant as previously expected. No general algorithm was found that could be used to predict these effects across the range of circuits tested.
Date: 1995
Creator: Peterson, Jeffrey Shawn
Partner: UNT Libraries Government Documents Department

Adhesion of Diamond Films on Tungsten

Description: The U.S. Bureau of Mines has investigated the chemical vapor deposition of diamond films on tungsten substrates. The effects of deposition parameters on the adhesion of the films was determined. The films were produced using a hot filament chemical vapor deposition system. Parameters investigated were substrate temperature and methane concentration in the feed gas. Film quality, morphology, and composition were characterized by scanning electron microscopy and Raman spectroscopy. Adhesion testing was performed using an indentation technique, and the results were quantified by relating adhesion to interface fracture toughness. Diamond films with well-faceted crystalline morphology with grain size greater than 1 pm had poor adhesion properties regardless of substrate temperature or methane concentration. Diamond films with smooth morphologies consisting of rounded clusters of small (<0.2 pm) diamond crystallites and amorphous carbon phases displayed much higher adhesion, although the conditions that led to the growth of these films are not understood.
Date: 1995
Creator: Maggs, K. J.; Walkiewicz, J. W. & Clark, A. E.
Partner: UNT Libraries Government Documents Department

A Kinetic Model for Conventional Flotation of Coal

Description: The U.S. Bureau of Mines has developed a computer model to 'describe a flotation process. Coal data from conventional flotation has been converted to a simple, two-parameter kinetic model developed by Reuter and van Deventer (j,2 3. Each set of coal data was represented by two constants, a and a, and an average flotation rate. The success of the model was demonstrated when the calculated and experimental recoveries showed good correlation. The two-parameter model allows complex data to be defined much more efficiently than traditional knowledge-based models.
Date: 1995
Creator: Susko, Frank J. & Stanley, Don A.
Partner: UNT Libraries Government Documents Department

3DTOM, Three-Dimensional Geophysical Tomography

Description: Abstract: 3DTOM is a DOS-compatible computer program developed by the Mines U.S. Bureau of for three-dimensional tomographic imaging of the subsurface at mine sites. The program uses the simultaneous iterative reconstruction technique (SIRT) to invert travel- time data and produce maps of wave velocity, or to invert amplitude data and generate maps of wave attenuation coefficients. Either seismic (compressional and/or shear) or electromagnetic (e.g., radio or radar) wave data may be used. Ray tracing in 3DTOM uses several different methods, including ray bending, network theory, and a combination of these. User-defined constraints are important in reducing the mathematical nonuniqueness of inversions based on limited data. 3DTOM permits the use of hard constraints, or soft constraints based on fuzzy logic, to allow for uncertainty in the constraints. Reliable subsurface images are useful in many different mine-related problems, including void detection, fracture detection, fluid monitoring, and qualitative stress evaluation.
Date: 1996
Creator: Jackson, M. J. & Tweeton, Daryl R.
Partner: UNT Libraries Government Documents Department

Hazards of Conveyor Belt Fires

Description: This report describes a U.S. Bureau of Mines study on the hazards of large-scale conveyor belt fires in underground coal mines, as a function of both air velocity and distance from belt surface to gallery roof. The fire hazards considered were smoke obscuration, toxic effects of carbon monoxide (CO), and elevated air temperatures downstream of the fire. All of these hazards scale with the ratio of fire intensity to ventilation airflow. These hazards were all found to be greater at the lower belt-to-roof distance, owing to the greater fire intensities that resulted. The hazards of smoke obscuration and elevated CO levels were greater at lower air velocities. Smoke obscuration was found to be the earliest hazard, reaching critical levels before the stage of belt flame spread. Critical levels of CO and downstream air temperatures were not reached until the later stages of flame spread. Fire growth rates during rapid flame spread were much greater than rates measured during the early stages of belt burning. Data were analyzed to determine the early-warning capability of fire sensors. Smoke sensors provided the earliest warning, followed closely by CO sensors. Thermal sensors did not exhibit any early warning capability.
Date: 1995
Creator: Perzak, Frank J.; Litton, Charles D.; Mura, Kenneth E. & Lazzara, Charles P.
Partner: UNT Libraries Government Documents Department

Dust Control Considerations for Deep-Cut Mining when Utilizing Exhaust Ventilation and a Scrubber

Description: Abstract: The U.S. Bureau of Mines conducted a series of laboratory tests to investigate the effectiveness of using a flooded-bed scrubber with exhaust ventilation in deep-cut faces of up to 12.2 m in length. An experimental test program to determine the impact on respirable dust levels resulting from changes in face airflow, curtain setback distance, operator positioning, and operating parameters of the external spray system on the miner was completed. Gravimetric sampling was conducted in the immediate return and at three sampling locations on the off-curtain side of the entry. Statistically significant differences in dust levels on the order of 0.5 to 1.2 mg/m3 were observed between specific sampling locations and changes in several test parameters. Several of the statistically significant relationships were found at the inby operator position, which is the least desirable of the operator locations that were tested. The relative effectiveness of the dust control at the other sampling locations was not severely impacted with the scrubber operating. Dust control was the primary focus of this research; results indicated that a flooded-bed scrubber and exhaust ventilation can be a viable system for extracting deep cuts up to 12.2 m in length. The impact on methane was not evaluated.
Date: 1996
Creator: Colinet, Jay F. & Jankowski, Robert A.
Partner: UNT Libraries Government Documents Department