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: 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 …

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 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: 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.

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.

From abstract: The U.S. Bureau of Mines Reno Research Center investigated, developed, and patented a high temperature cyanide leaching process for recovering platinum-group metals (PGM) from automobile catalysts. A batch pilot plant was constructed at the center and operated to demonstrate this technology to industry.

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.

Abstract: The first step in determining whether Mn can be recovered by in situ leaching is to develop and test a selective lixiviant. Two column leach tests and one core leach test were conducted by the U.S. Bureau of Mines on Mn oxide ore using aqueous sulfur dioxide (SO2) as the lixiviant. The column tests showed that aqueous SO2 could selectively dissolve available Mn oxides from calcite-rich ore in a heap leach system. However, the core test showed that calcite gangue side reactions can have pronounced negative effects on the likelihood of successful in situ leaching of a calcite-rich ore with aqueous SO2. Petrographic and geochemical analyses showed that both Mn (IV, II) oxides and calcite were dissolved. The abundance of dissolved Ca caused precipitation of gypsum. Acid consumption by calcite dissolution caused a rise in pH that caused the S02/S species to shift to SO32- (sulfite), which hindered reductive dissolution of Mn oxide. Gypsum precipitation did not affect complete leaching of the rock fragments in the column tests; however, it plugged the natural permeability in the core. Manganese recoveries were high for the column tests and low for the core test.

Abstract: This U. S. Bureau of Mines (USBM) report presents results of stress analyses and field observations to investigate the effects of elevated trench drifts on the structural stability of rock mass zones surrounding a production draw drift in a mine utilizing a mechanized load-haul-dump (LHD) trench undercut panel caving system. A two-dimensional boundary-element mine stress model was developed to predict the locations and extent of damaged rock mass zones surrounding draw drifts where adjacent, parallel trench drifts are either elevated or not elevated above the LHD production draw drift level. A Mohr-Coulomb shear-failure criterion was obtained directly from in situ borehole shear test data. Hoek-Brown shear-failure parameter values were computed from borehole-shear and triaxial test data. A procedure is described to estimate these parameters when a rock mass rating (RMR) value and triaxial data on intact samples exist, and no borehole shear test data exist. Results indicate that trench drifts, elevated to the level equal to the height of the LHD production draw drift, would not minimize material damage nor significantly enhance the stability of rib and crown pillar zones surrounding production draw drifts in the mechanized LHD trench undercut caving panel investigated at this mine.

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 …

Report issued by the Bureau of Mines over studies conducted on hazard control in talc mines. Methods of testing, and results of the study are discussed. This report includes tables, maps, illustrations, and photographs.