Abstract: During the week of September 4, 1995, personnel from the U.S. Bureau of Mines conducted a Ra-226 survey at the Midnite Mine. One hundred thirty measurements were made on a rectangular grid with 150-m spacings. Concurrently, Shepherd Miller, Inc., took gross gamma readings in gR/h at the same grid points. In addition, the USBM collected 17 soil samples to be analyzed for radium, thorium, and potassium. The results of this survey are summarized in this report.

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.

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 …

Abstract: A geographic information system (GIS) database has been developed by the U.S. Bureau of Mines (USBM) for the Midnite Mine and surroundings in northeastern Washington State (Stevens County) on the Spokane Indian Reservation. The mine is an open pit uranium mine which has been inactive since 1981. The GIS database was compiled to serve as a repository and source of historical and research information on the mine site. The database supported USBM hydrological and reclamation research on the mine site. The database also will be used by the Bureau of Land Management and the Bureau of Indian Affairs (as well as others) for environmental assessment and reclamation planning for future remediation and reclamation of the site. This report describes the data in the GIS database and their characteristics. The report also discusses known backgrounds on the data sets and any special considerations encountered by the USBM in developing the database. Most of the database also is planned to be available to the public as a two-CD-ROM set, although separately from this report.

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 …

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 …

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.

Abstract: The Midnite Mine is an inactive, hard-rock uranium mine on the Spokane Indian Reservation in Washington State. Oxidation of sulfide-containing minerals, primarily pyrite, produces large quantities of 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. Long-term changes in water quality and the results of slug tests and two geophysical surveys are described. Of the locations monitored, only two exhibited water quality degradation over time. Hydraulic conductivity measurements from slug tests are reported for five additional locations in the bedrock. Relative values of hydraulic conductivity from slug tests agreed well with ranked specific capacity data. A geophysical survey identified buried constructed features that channel subsurface water to a contaminated seep. Historic aerial photos corroborated the results of the geophysical study. A new geophysical technique was successfully used to monitor hydraulic and geochemical responses to a pumping test …

Abstract: The U.S. Bureau of Mines is conducting full-scale laboratory studies on the development of lightweight inflatable devices that can be used for rapidly isolating mine fire areas to allow for fire suppression and/or personnel escape. These inflatable devices were able to stop airflows of over 1,100 m3/min within several minutes. The remotely installed bag was designed to rapidly isolate the fire zone and to then serve, if necessary, as a containment form for the remote injection of low-dersil organic or inorganic foams. Other inflatable bag concepts that were tested include an inflatable feed-tube seal for high-expansion foam generators and a positive pressure inflatable walk-through escape device. Laboratory studies indicated that a high-expansion foam plug will travel 183 m through an entry with a 4.5 pct rise in elevation before foam leakage from around the inflatable feed-tube seal. Additionally, the positive-pressure, inflatable walk-through escape device with its "pass-through" feature may allow extra time for personnel evacuation. All of these inflatable devices have shown merit during laboratory studies in providing a rapid method for isolation of a mine fire prior to suppressant foam injection or personnel escape.

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.

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.

The Midnite Mine is an inactive open-pit uranium mine located on the Spokane Indian Reservation in Washington State. Drill samples from two large waste rock dumps on the site, known as South Spoils and Hillside Dump, were collected with a Becker hammer drill and evaluated to determine potential of the rock to generate acid mine drainage (AMD). Waste rock at this mine contains both pyrite and uranium, and AMD effects are more complicated on this site than most in that uranium is soluble in both acidic and neutral aqueous solutions. Although AMD protocols identified 26% of the South Spoils samples as potentially acid, under 7% of the spoil samples were actually producing acid. Considerable calcite exists in the South Spoils, and weathering feldspars further contribute to acid neutralization. The Hillside Dump has low concentrations of pyrite and calcite that acid-base accounting protocols would predict to be non-acidic. Accumulation of sulfate in rocks with concentrations of less than 0.3% S causes some of those normally non-acid producing rocks to produce acid in the Hillside Dump.

Abstract: Researchers at the U.S. Bureau of Mines conducted field investigations at the Greens Creek Mine in southeast Alaska for the purpose of validating computer design of mining methods and assessing real-time monitoring capabilities. The field study required the application of new technology because of the remoteness of the study site, the need for timely acquisition of data, and a limited budget for instruments and data acquisition. Various sensors were installed to monitor rock mass deformation and strain, temperature, SO gas emissions, and blasting. Data were collected through a distributed personal computer network and high-speed modems. These readings were used to develop visualization models of underground metal mining operations and drift-and-fill mining and real-time graphics displays of ground conditions. Results of the field tests showed that it is possible to gather, process, visualize, and verify mine designs on a real-time basis.

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.

Abstract: Researchers at the U.S. Bureau of Mines (USBM) have developed adaptive process control systems in which genetic algorithms (GA's) are used to augment fuzzy logic controllers (FLC's). GA's are search algorithms that rapidly locate near-optimum solutions to a wide spectrum of problems by loosely modeling the search procedures of natural genetics. FLC's are rule-based systems that efficiently manipulate a problem environment by modeling the "rule-of-thumb" strategy used in human decisionmaking. Together, GA's and FLC's include all of the capabilities necessary to produce powerful, efficient, and robust adaptive control systems. To perform efficiently, such control systems require a cont element to manipulate the problem environment, an analysis element to recognize changes in the problem environment, and an adaptive element to adjust to the changes in the problem environment. The control system also employs a computer simulation of the problem environment. Details of an overall adaptive control system are discussed. A specific laboratory acid-base pH system is used to demonstrate the ideas presented; all results are from the physical laboratory system and not from a computer simulation.

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.

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.

Abstract: The U.S. Bureau of Mines, Tuscaloosa Research Center, in cooperation with the U.S. Army Corps of Engineers under interagency Agreement No. 14-09-0078-1510, conducted a comprehensive sampling program of 10 upland disposal sites along the Alabama, Black Warrior, and Tombigbee River systems in Alabama. Samples from each site were characterized according to particle size, chemical analysis, mineralogical content, and potential end use. Additionally, samples were subjected to the Toxic Characteristic Leachate Procedure to determine the presence of potentially harmful heavy metals. Based on the results of these studies, each sample was determined to have properties amenable for use as aggregate in general-purpose portland cement concretes and certain asphalt concrete applications.

This U.S. Bureau of Mines study examined spontaneous heating episodes in coal mine pillars in an active underground coal mine. The information obtained from these incidents was then analyzed to learn which sampling methods provided the earliest indication of pillar heating. The objective of this study was to discover if the location of future events of pillar spontaneous heating could be inferred from the available information. The spontaneous heating-prone area in this evaluation involved pillars located just in by the mine portals. Several detection methods were used to determine gas levels outside as well as inside the affected pillars. It was hoped that, by incorporating external and internal sampling methods into an organized program, locations undergoing spontaneous heating could be determined more readily. This study found that by drilling small-diameter boreholes into the pillars, then obtaining gas samples from the affected pillars, the ability to locate early spontaneous heating episodes was improved. However, the ability to accurately predict future spontaneous heating events remains in question.

Standard smoldering and flaming combustion tests using small coal samples have been developed by the U.S. Bureau of Mines as a method to evaluate the response of a smoke detector. The tests are conducted using a standard smoke box designed and constructed according to Underwriters Laboratories. The tests provide a standard, easily reproducible smoke characteristic for smoldering and flaming coal combustion, based upon a comparison of the smoke optical density and the response of a standard ionization chamber to the smoke. With these standard tests, the range of threshold limits for the response of a smoke detector and the detector's reliability can be evaluated for nearly identical smoke visibility and smoke physical characteristics. The detector's threshold response limits and reliability need to be well defined prior to the instrument's use as part of a mine fire warning system for improved mine safety.

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.

Abstract: The hazards to the public posed by abandoned mine shafts are well documented. As private development encroaches on previously mined areas, the potential for fatalities and serious injuries from abandoned mine shafts increases. The U.S. Bureau of Mines has conducted research into cellular concrete as a material for sealing these openings. The current work involves testing the characteristics of cellular concrete before and after it had been pumped or dropped from different heights into a simulated mine shaft. Cellular concrete was pumped vertically up to and subsequently dropped from heights of 18 and 37 m into concrete forms. Wet density measurements were made at multiple sampling points in the test circuit. Air content determinations and uniaxial compressive strength testing were conducted. Research results showed significant loss in air content and changes in the characteristics of cellular concrete during pumping or dropping from various heights. Recommendations on effective use of cellular concrete for sealing abandoned mine shafts are made.

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.

Abstract: This U.S. Bureau of Mines (USBM) report summarizes a field demonstration of pneumatic backfiling technologies conducted at the abandoned Hillside Coal and Iron Slope in Vandling, PA. Researchers demonstrated tro pneumatic backfilling technologies recently developed under the USBM's Abandoned Mine Reclamation Research Program, the Pneumatic Pipefeeder and the High-Efficiency Ejector. Both systems had previously been evaluated at the USBM's subsidence abatement investigation laboratory near Fairchance, PA. The objective of the demonstration was to fill 100% of the abandoned tunnel with backfill stone to prevent further subsidence. The Pneumatic Pipefeeder was used for 21 days, at a rate of 63 to 124 t/d (69 to 136 st/d), to fill 88% of the tunnel. The High-Efficiency Ejector was used for 2 days, at a rate of 125 to 132 t/d (138 to 146 st/d) to fill the remaining 12% of the tunnel. The backfill placed by both systems was tightly compacted. The major problem encountered was wear on the polyethylene pipeline from the abrasion of the high-velocity backfill. The use of heavier steel pipe minimized the problem. A cost analysis for the entire project is given.