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By Edward L. McHugh

The appraisal of mineral resources of the Challis National Forest, Idaho, by the U.S. Bureau of Mines, was made so that the mineral resources of the forest could be appropriately considered in land use planning. Information from this study is intended to help the U.S. Forest Service to incorporate mineral resource data into forest plans. The study was done in conjunction with the U.S. Geological Survey, which released a companion report on the geology and mineral potential of the Challis National Forest in 1989. Mineral development activity in and under the Challis National Forest has been of great economic significance to Idaho and the United States. Since the 1960's, mines within the forest have produced mineral commodities worth more than $590 million A current (1989) commodity prices. Identified mineral resources have a gross value of about $2 billion at current prices, including 8 strategic or critical minerals. The U.S. Bureau of Mines study identified and described 723 active and inactive mineral properties within the forest. Mineral properties with identified resources were evaluated to determine their economic significance, and an assessment was made of the feasibility of mineral development. Of the 2,516,191 acres in the Challis National Forest, about 390,000 acres were classified as having mining development interest commercially important mineral production, mainly of molybdenum, gold, and silver from the Challis National Forest is likely for the foreseeable future.

Jan 1, 1991

By S. W. Zoldok

[The Bull Valley iron-ore district lie,; in the northern part of Washington County, Utah, approximately 30 airline miles southwest of the highly productive Iron Springs area (fig. 1). Iron-ore occurrences in the district have been known for many years, but they have not been mined, largely because of the inaccessibility of the area. The Bureau of Mines established a development project in the Bull Valley district in September 1941. Two separate areas, the Pilot and the Cove Mountain, were investigated. The work was planned to increase iron-ore reserves for steel production in the Western United States. During the project period three diamond-drill holes aggregating 1, 000 feet were completed (fig. 2). The program also included 6 408 linear feet of surface trenching and 171 feet of underground work (figs. 2 to 8, inclusive). Analyses were made of 460 samples from the diamond-drill holes and surface and underground excavations. The results of the analyses are given in tables 1, 2, 4, and 5, and the logs of the diamond-drill holes are shown in table 3. Field. work was completed in September 1942.]

Jan 1, 1953

By E. D. Gardner

Humphreys Gold Corporation of Denver, Colo., was conducting a successful placer operation in 1936 on North Clear Creek about 6 miles below Blackhawk in Gilpin County, Colo. About 3,000 cubic yards of gold-bearing gravel are dug daily (September. 1936) by two draglines and a power shovel. The gravel is screened in a portable washing plant; the trommel oversize is discarded, and the undersize is pumped to a gold-saving plant. The gold is caught in riffles in sluice boxes. The total cost of mining is about 20 cents per cubic yard. The mine is in a narrow canyon at an altitude of 7,200 feet. The Blackhawk-Central City branch of the Colorado & Southern RR. runs over the property. Freight platforms for receiving supplies were moved as the workings advanced. The workmen reached the mine on a speeder that ran on the railroad tracks from a point on the automobile highway (U. S. 40) on Clear Creek near the bottom of Floyd Hill, about 5 miles distant. The mine is 36 miles by road and speeder, or 30 miles by rail, from Denver.

Jan 1, 1937

By R. T. Sorensen

Bench-scale and continuous testing were performed to adapt the anionic process for flotation of calcium activated silica to the fine-grained hematitic-goethitic jaspers from the Marquette range, Michigan. These ores typically contain about 35 percent Fe and require grinding to about 80 to 100 percent minus 400 mesh to insure an adequate liberation of gangue from the iron oxides. A method for removal of troublesome slime fractions without excessive iron loss, by first dispersing the quartz and then selectively flocculating the iron oxides, was evolved in the laboratory and successfully accommodated to pilot plant practice. The efficiency of the flotation process was improved with respect to both reagent usage and concentrate grade and recovery by using the selective flocculation-desliming technique as a pretreatment. The benefits of the combined desliming-flotation procedure were most evident in pilot plant processing. The best tests on two ores yielded recoveries of about 84 percent in concentrates containing 65.1 percent Fe and 4.8 percent SiO2 and 66.2 percent Fe and 3.9 percent SiO2, respectively. These results are in comparison to recoveries about 10 percent lower than the above to concentrates containing 63.9 percent Fe and 6.6 percent SiO2 in the one instance, and 63.6 percent Fe and 7.2 percent SiO2 in the other, obtained by flotation without the prior desliming treatment.

Jan 1, 1967

By David E. Nicholson

In a Bureau of Mines investigation of the dynamic compaction of mine hydraulic backfills, two basic forms of mechanical vibration inducers were used and compared for effectiveness of compaction. Internal compaction, using concrete probe vibrators of various sizes, and external compaction, using plate vibrators} were studied and evaluated for use in underground stopes. An aluminum plate, which was light and displaced sufficient volume to remain afloat in fluid fill, and a steel plate were both used in the external compaction tests. Efficiency of compaction was better in studies conducted with internal probe vibrators. Tests were conducted in an underground backfilled stope with three different-sized probe vibrators (2-, 4-, and 6-inch-diameter) to determine an approximate area of influence. Results showed the areas of influence to be approximately 3, 4, and 5 feet in diameter, respectively, for the three different probes. Physical properties of hydraulic slurries were determined; preferred grain-size distributions, water exudation properties, and water contents of hydraulic slurries are reported. The best compaction results were obtained with moderately well-graded, fully saturated backfills, with slow rates of water exudation, which were capable of remaining in a semifluid state during the compaction process.

Jan 1, 1967

By R. Hogg, T. F. Dumm

"It is generally agreed that dust characteristics play a role in the development of Coal Workers' Pneumoconiosis (CWP). Unfortunately, there is a serious lack of information on what the characteristics of mine dust actually are and how they vary among different mining regions, coal seams, etc. This paucity of data can generally be attributed to the serious problems encountered in collecting sufficiently large quantities of dust for conventional analytical procedures.Personal samplers are widely used in coal mines for regulatory and enforcement purposes. Generally, these provide information only on the total (respirable) dust loading in the mine atmosphere and on the mineral matter (primarily quartz) content of the respirable dust. A procedure has been developed by which samples collected with a slightly modified personal sampler can be analyzed for particle size distribution, total mineral matter content and elemental composition, in addition to the standard mass and quartz measurements. These analyses could readily be performed on a routine basis. Shape analysis by Scanning Electron Microscope (SEM) could easily be included if appropriate shape criteria are established. Extension of the procedure to include the determination of complete size/specific gravity (composition) distributions is quite straightforward provided sufficiently large samples (at least 10 mg) can be collected. Typical sample sizes for a personal sampler carried by a miner for one shift range from about 0.5 to 2 mg.The basic procedure was developed and evaluated using synthetic mine dust prepared in the laboratory. Field tests in three working mines in Pennsylvania and West Virginia have confirmed the applicability of the approach to the real world. Particle size distribution measurements on mine dust collected in the modified personal sampler were found to agree closely with the results of simultaneous in situ measurements obtained using cascade impactors."

Mar 1, 1989

By William O. Vanderburg

This report3/ gives the results of a reconnaissance of mining districts in Eureka County, Nevada, made from September 25 to October 20 and from October 27 to November 5, 1577. During this time, virtually all the districts were visited and many data obtained on active and inactive properties. This report covers the locations of the various districts, geological background, ownership and brief descriptions of mines and prospects, information on past and current operations, and, other data likely to be useful to those interested in the development of our mineral resources. From the viewpoint of past production in the county, the silver-lead-gold deposits at Eureka have been tie most important, followed by the silver deposits at Cortez and Mineral Hill. The period of greatest activity in the foregoing districts was from 1870 to 1990, when Eureka was one of the principal mining areas in Nevada; the production of lead was sufficient to affect its price in all the commercial centers of the world. Eureka also merits the distinction of being the birthplace of the silver-lead smelting industry in the United States.

Jan 1, 1938

By Warren E. Morrison

This study was prepared in response to the need for a series of data that reflect the basic flow pattern of energy resources in the United States. To effectively measure and analyze energy,2 it is necessary to prepare balances that reflect both production and consumption, and the various forms energy resources take at different stages of utilization. Before energy can be measured it must also be put into a common unit. In this study the common unit used is the British Thermal Unit (Btu). The ideal point to survey energy is at the stage of final ultimate use, representing the useful work derived from the interaction of energy inputs and the prime mover. Unfortunately this concept of efficient or useful work from energy output cannot readily be measured in the aggregate. With the present available official data, energy measurement can be carried to the point of calculation of net inputs of energy3 into the economy at various stages of utilization. However, preparation of energy balances, on a net basis is hampered by the fact that this can only be done for years when the censuses of Mineral Industries and Manufactures are taken, usually at 5-year interval.

Jan 1, 1964

By W. D. Mcmillan

Important reserves of nickel ore occur in the Levies district in Oriente, Cuba. The area is mountainous and mostly covered by heavy vegetation. The ore bodies comprise surface tracts of nickeliferous laterite underlain with decomposed serpentine of ore grade. The Cuban Nickel Co., a wholly owned United States Government corporation, owns a plant for leaching the nickel from its ores at Nicaro, Oriente, Cuba, Between December 1943 and March 31, 1954, 5,902,225 short tons of ore was treated, with a recovery of 116,206,519 pounds of nickel (52,711 metric tons). In 1953, 1,330, 224 short tons of ore was mined and 27;"3,129 pounds of nickel produced. The Cuban Nickel Co. also owns a townsite, with the necessary facilities, mining equipment, and 11 miles of railroad. Ore for the plant has been produced from the Ocujal-San Juan claims on lends owned by the Nicaro Nickel Co., a sub¬sidiary of Freeport Sulphur Co. The Government enterprise is man-aged by the Nickel Processing Corp. The Cuban Nickel Co. has denounced mineral concessions and has purchased other claims from private owners.

Jan 1, 1955

By Thomas M. Barczak

This U.S. Bureau of Mines report chronicles the historical development of longwall mining in the United States and speculates on future developments to the turn of the century. The involvement and contributions made by the Bureau during these developments are also discussed. Two major periods of history are analyzed: (1) from 1875 to 1950 when small advancing faces were operated manually, and (2) from 1950 to 1990 when mechanized extraction and powered roof supports provided a system to efficiently extract large coal panels. Five eras of technological development during the modern period are described and analyzed. These eras discuss the development of (1) mechanized extraction, (2) powered roof supports, (3) high-capacity roof supports, (4) shield supports, and (5) system automation. Current trends are analyzed in terms of longwall utilization, face production, support capacity, face widths, and new technological developments. From these analyses, the future of longwall mining to the year 2000 is speculated. It is concluded that longwall mining will continue to grow in importance during the next decade and that the next major technological milestone will be the realization of a fully automated longwall mining system.

Jan 1, 1992

By C. L. Karr

U.S. Bureau of Mines (USBM) research has shown that fuzzy logic and genetic algorithms (GA's) have great potential for industrial process control. A technique has been developed by the USBM in which GA's are used to substantially reduce the time needed to design fuzzy logic controllers (FLC's).This technique shows promise as an efficient, robust approach to developing control systems. The research described in this report is twofold. First, the basic approach to developing an FLC using GA's is presented. The GA-designed FLC is developed for a specific physical system, a pH titration system. Second, empirical results are presented in which variations in the FLC implementation are compared. Specifically, the effects of altering five aspects of the pH FLC are considered: (1) membership function form, (2) number of fuzzy classes, (3) the center-of-area method, (4) implication operator, and (5) fuzzy rule form. Results indicate that (1) the technique in which GA's are used to design FLC's is effective, and (2) when this technique is used, variations in FLC implementation have little effect on FLC performance in a chosen control problem.

Jan 1, 2010

By C. W. Davis

This paper is the second of a series of progress reports on a study, of the hydrometallurgy of manganese which is being conducted in an endeavor to make possible utilization of the large deposits of low-grade domestic manganese ores that occur in several States. There are at least four processes in which a knowledge of the action of SO2 gas on manganese oxides at elevated temperatures may prove of value. One ,of these involves dissolution of manganese from ores. The Bureau of Mines has investigated the hydrometallurgy of manganese by a process in which SO2 gas, a waste product at many smelters, is passed into water to form a solvent for manganese. Although Several manganese minerals acre readily dissolved, rhodochrosite (MnCO3) was attacked but superficially.§. Recent experiments have shown that a roast at 650 to 900°C converts the manganese of rhodochrosite to a form that is quickly dissolved by a weak SO2 solution. Introduction of smelter gases containing as much as 5 per cent SO2 during such a roast would not add much to the cost of the operation and might result in the formation of considerable water-soluble manganese sulphate.

Jan 1, 1930

By Gregory B. Beacher

Analyses have been performed on geotechnical properties of copper, uranium and phosphate (gypsum) tailings materials, with the intent of identifying typical measures of variability within and among sites, and of characterizing such variability for use in reliability modeling of tailings embankments. In all, data from approximately 41 sites were analysed. Fairly consistent results were obtained for within site variabilities. However no one probabilistic model was found to be applicable to all sites. The distributional forms for most of the data sets are regular, and tend toward Normality when spatial trends are removed. At many of the sites sufficient in situ data were available to allow estimates of vertical autocorrelation distances and measurement noise. Available data indicate that variability in pore pressures may have a more important effect than strength property variation. A major problem in interpreting available strength property data results from the unknown drainage conditions during testing.

Jan 1, 1983

By Thomas M. Barczak

This U.S. Bureau of Mines (USBM) report evaluates the load supporting characteristics of grout columns used as point supports for mine subsidence abatement. The cone-shaped columns were constructed with sodium silicate and cementitious grout in both wet and dry environments. The scope of work included the testing of seven full-scale grout columns in the USBM's Mine Roof Simulator from which the load-deformation and failure characteristics were determined. The performances of grout columns are analyzed with respect to (1) the amount of roof contact established during column construction, (2) shape effects produced by the truncated cone geometry, (3) size effects in reference to grout strength and full-scale column capacity, (4) the effect of wet environments on grout strength, (5) the effect of the sodium silicate on the grout strength and full-scale column behavior, and (6) the stiffness of the grout column. Limited tests were also conducted on cylindrical columns constructed in fabric bags. Recommendations for point support construction using sodium silicate technology and the need for additional research to develop improved containment devices for column construction are addressed in the report.

Jan 1, 2010

By Robert B. Hoekzema

The Bureau of Mines and U.S. Geological Survey completed a 4-yr (1979-82) mineral appraisal of the Chugach National Forest (CNF), AK. This report summarizes the Bureau's placer gold studies in the CNF. Placer mining from the mid-1890's through 1982 produced an estimated 133,800 oz of gold, of which two-thirds was produced prior to 1920. As much as 6,800 oz of placer gold was produced from 1979 to 1982. Most production came from Crow, Canyon, and Resurrection Creeks. Five types of placer gold deposits were identified in the CNF: (1) alluvial placers, (2) bench placers, (3) eluvial placers, (4) glacial placers, and (5) marine placers. Placer sampling indicated a potential for gold production from alluvial and bench placers associated with historically mined drainages such as Crow, Canyon, Resurrection, Sixmile, and Mills Creeks and from unmined drainages including the Avery, Kings, Snow, Copper, and Tasnuna Rivers and several smaller streams throughout the CNF. Results of fineness tests indicated that gold from the CNF ranges from 455 to over 950 fine. Subsequent investigations in drainages with anomalous placer sample values also identified previously unknown lode mineralization.

Jan 1, 1986

The 1963 Lignite Symposium was held on the University of North Dakota campus, Grand Forks, N. Dak., April 30-May 1, 1963, under the cosponsorship of the University of North Dakota and the Bureau of Mines. This symposium, the third in a series, had as a general objective the dissemination of information concerning advances in technology and utilization of solid fuels, with emphasis on lignitic coals. Approximately 150 representatives of industry, government, and educational institutions from 21 states and 3 Canadian provinces were present at the symposium. Those attending were welcomed by Marling J. Ankeny, Director of the Bureau of Mines, representing the Bureau, and Dean T. H. Clifford, Vice President of the University, representing the University.

Jan 1, 1964

The 1963 Lignite Symposium was held on the University of North Dakota campus, Grand Forks, N. Dak., April 30-May 1, 1963, under the cosponsorship of the University of North Dakota and the Bureau of Mines. This symposium, the third in a series, had as a general objective the dissemination of information concerning advances in technology and utilization of solid fuels, with emphasis on lignitic coals. Approximately 150 representatives of industry, government, and educational institutions from 21 states and 3 Canadian provinces were present at the symposium. Those attending were welcomed by Marling J. Ankeny, Director of the Bureau of Mines, representing the Bureau, and Dean T. H. Clifford, Vice President of the University, representing the University.

Jan 1, 1964

By Jr. Frank Parrish

This report describes the performance of 17 selected water-injection projects producing from Pennsylvanian-and Permian-age reservoirs. Illustrations depict reservoir structure and thickness, and production and injection history. A selected bibliography of publications pertaining to area oil recovery and geology is included. Tabulations of field and reservoir data reveal marked differences in the projects. Increased oil recovery resulted from injecting water in most cases; however, seven projects recovered less oil than the operators anticipated. Oil recovery by water injection ranged from 0.2 to 262 bbl per acre ft, or 0.1 to 22.5 pct of the initial stock-tank oil in place. Major reasons suggested for poor performance include: (1) Adverse directional horizontal permeability, (2) channeling of injected water through fractures or zones of high permeability, and (3) lack of containment of injected water. One 330-foot-deep project is among the first successful shallow water-floods in north Texas. Another project is the first successful Canyon sand-stone waterflood reported in the area. Previous gas injection in two Cisco sandstone projects did not prevent the reservoirs from responding favorably to waterflooding.

Jan 1, 1965

By V. A. Marple, K. L. Rubow

"In our laboratory several impactors have been developed in the past which have penetration characteristics that approximate that of the ACGIH or the British MRC respirable curves. In these impactors the large nonrespirable particles are collected on an impaction plate of a multiple round nozzle stage where the nozzles are of different diameters. The principle for designing a respirable cut impactor is quite simple in that the respirable curve is divided into two or more segments and the nozzles are designed with the correct diameters and number of nozzles to have collection characteristics with 50% cutpoints at the center of each segment. The particles not collected on the impaction plates are then collected upon a filter. These particles represent the respirable fraction of the aerosol. Therefore the respirable curve is approximated in a stepwise fashion with the approximation becoming better as the respirable curve is divided up into increasing numbers of segments. It has generally been felt that three segments is satisfactory for most cases.A new version of the respirable impactor has recently been developed in our laboratory. This impactor approximates the ACGIH respirable curve in three steps at a flow rate of 30 liters per minute. However, unlike previous models where all of the particles larger than the three cut points designated by the three steps are collected upon one impaction plate, a separate impaction plate is now used for each of the three cut sizes. To approximate the respirable curve in three steps, the cut sizes must be 2.2, 3.5 and 5.8 microns diameter. Therefore, on each of these stages the particles collected will be the mass of particles that are larger than these three cut sizes. By determining the mass of particles collected on each of these three stages plus that on the after filter using Gravimetric techniques, some information can be obtained on the size distribution of the aerosol being sampled. Furthermore, the impaction plates of the three stages are rotated and the nozzles are placed in such a position such that a uniform deposit is obtained on each of the impaction plates. Therefore, the deposits collected are suitable for X-ray fluorescence analysis or other types of analysis where a uniform deposit is required."

Jan 1, 1988

By Van H. Manning

EXPLOSIVES RESEARCH. As the physical laboratories of the explosives section of the Pitts- burgh experiment station were equipped for testing the physical properties of explosives, both the Army and Navy Departments for many years had requested the Bureau of Mines to make such tests. Chemical control of the physical tests through analyses, heat tests, analyses of gaseous products of combustion, and sand tests was exer- cised through the explosives chemical laboratory. Often an investigation was cooperative between two laboratories. The explosives chemical laboratory also aided the work of the Ex- plosives Regulation both by chemical tests and investigation of acci- dents in explosives plants. COOPERATIVE WORK FOR ARMY AND NAVY DEPARTMENTS. The explosives chemical laboratory devised, at the request of the Bureau of Ordnance of the Navy, a more economical method of making hexanitrodiphenylamine. This problem was assigned to the Bureau of Mines by Dr. C. E. Munroe, chairman of the committee on explosives of the National Research Council, acting as the depart- ment of science and research of the Council of National Defense. Before the United States entered the war the following reports of investigations were submitted to the Army or the Navy: 1. Report of sensitiveness and relative efficiency of TNT and ammonium picrate, dated February 6, 1913, undertaken at the re- quest of the Chief of Ordnance. 2. Report of tests and examination of two samples of TNT and one of TNA for the Ordnance Department of the Army, dated August 5, 1915, was undertaken at the request of commanding officer, Frankford Arsenal. 3. Report of tests for sensitiveness to detonation of mercury ful- minate of 21 samples of TNT crystallized from various solvents, for the Bureau of Ordnance, Navy Department, dated June 17, 1916. 4. Report of tests of two samples of mercury fulminate for Frank- ford Arsenal, dated December 2, 1916, undertaken at the request of the commanding officer, Frankford Arsenal. After the United States entered the war the following reports of investigations were submitted: 5. Report of pendulum friction and large impact tests on two samples of "sodatol" and two samples of "amatol." The final report was dated July 20, 1918; and the preliminary report, May 15, 1918. This investigation was undertaken at the request of the Ordnance

Jan 1, 1919