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.

Report issued by the Bureau of Mines over studies conducted on mine roof stability. Mining methods to improve roof stability are discussed. This report includes tables, maps, illustrations, and photographs.

Report issued by the Bureau of Mines over the reduction of underground mining hazards. Coal bed discontinuities are discussed. This report includes tables, maps, and illustrations.

Report issued by the Bureau of Mines over the geology of roof-rock stability in coal mines. The distribution, frequency, and magnitude of roof falls in U.S. coal mines are discussed. This report includes maps, illustrations, and photographs.

Report issued by the Bureau of Mines on the anthracite coal in the Bottom Red Ash Bed in Pennsylvania. The coal samples were analyzed for thickness and geologic structure. The amount of recoverable coal was also estimated. This report includes tables, maps, and illustrations.

Report by the Bureau of Mines over oil-recovery methods and experiments conducted in Warren County. Preparation, methods, and results of the experiments are presented. This report includes tables, graphs, maps, and illustrations.

Report issued by the Bureau of Mines over testing conducted on nickel oxide to produce nickel metal. Details of testing methods and results are presented. This report includes tables, illustrations, and photographs.

Report issued by the Bureau of Mines over investigations of coking-coal reserves of Clarion County, Pennsylvania. Methods used, and measurements of coal reserves are listed. This report includes tables, and maps.

Report issued by the Bureau of Mines over investigations of coking-coal reserves of Greene County, Pennsylvania. Methods used, and measurements of coal reserves are listed. This report includes tables, and maps.

Report issued by the Bureau of Mines over investigations of coking-coal reserves of Washington County, Pennsylvania. Methods used, and measurements of coal reserves are listed. This report includes tables, and maps.

Report issued by the Bureau of Mines over studies on the reserves of coking coal from Allegheny County, Pennsylvania. The results of the investigations and the different coal beds sampled are presented. This report includes tables, and maps.

Report issued by the U.S. Bureau of Mines regarding an investigation of the reserves of coking coal in Somerset County, Pennsylvania. The report includes tables and maps representing different coal beds within Somerset County.

Report issued by the Bureau of Mines over an annual study of synthetic liquid fuel production. Results of the annual study are presented and discussed. This report includes maps, tables, illustrations, and photographs.

Report of investigations issued by the U.S. Bureau of Mines evaluating the known reserves of coking coal in Jefferson County, Pennsylvania. The properties of coal and coal blends from the area are analyzed. This report includes tables, and maps.

Report issued by the U.S. Bureau of Mines on the known reserves of coking coal in Fayette County, Pennsylvania. Studies on the properties of coal and coal blends from the area are presented. This report contains tables, and maps.

Report issued by the U.S. Bureau of Mines on the estimate of the known reserves of coking coal in Westmoreland County, Pennsylvania. The report evaluates the properties of coal and coal blends from the area, and includes tables, and maps.

Report issued by the U.S. Bureau of Mines on the estimates of known reserves of coking coal deposits in Armstrong County, Pennsylvania. The properties of coal and coal blends from the area are presented. The report includes tables and maps.

Report issued by the U.S. Bureau of Mines on the known deposits of coking coal in Indiana County. The properties and characteristics of the coal and coal blends sampled are presented. The report includes tables and maps.

Report issued by the U.S. Bureau of Mines on estimates of known deposits of coking coal in Cambria County, Pennsylvania. Studies on the properties of coal and coal blends from the area are presented. The report includes maps and tables.

Report issued by the U.S. Bureau of Mines on the study of pumping at anthracite mines in Pennsylvania. The study was conducted in order to solve anthracite mine-water problems. The report includes maps, photographs, and illustrations.

Report issued by the Bureau of Mines over the progress made on flood prevention in anthracite mines. As stated in the report, "the broad objective of the investigative work was to obtain factual data on: 1. anthracite reserves of Pennsylvania, 2. underground water pools, 3. barrier pillars, 4. the "buried valley" of the Susquehanna River, and 5. infiltration of surface water into underground mine workings" (p. 4). This report includes tables, graphs, maps, photographs, and illustrations.

Report issued by the Bureau of Mines over studies conducted on flood-prevention developed for mine systems. A history of flood prevention procedures as well as updated flood-prevention is presented. This report includes tables, graphs, maps, photographs, and illustrations.

Report issued by the Bureau of Mines over flood-prevention methods at Pennsylvania anthracite mines. The flood-prevention projects are discussed. This report includes tables, maps, photographs, and illustrations.

Report issued by the U.S. Bureau of Mines on testing done on a variety of American coals collected from 32 coal beds across the country. The carbonizing properties of samples tested at 3 different temperatures are presented. This report includes tables, and graphs.