Search Documents

By Madan M. Singh

Hydraulic mining has been practiced in the United States since 1852 and many mineral commodities, such as gilsonite, phosphates, lead-zinc, silver ores and St. Peter Sandstone can be mined in this manner. In 1958, the U. S. Bureau of Mines initiated research into the mining of coal using these techniques.1-4 These early investigations were conducted in the 5000 psi pressure range. The large nozzle diameters used in this pressure range produced extremely high flow rates which created visibility problems at the coal face, and required removal of large amounts of water from the mining area. Besides, the production rates were not much better than with mechanical methods. This indicated that with higher pressures the water quantities might be reduced using the same or higher horsepowers but enhanced breakage. For this reason intensive investigation in material removal using fine water jets at extremely high pressures (50,000 psi to 100,000 psi) has been undertaken. This was not the entire reason for this contract from the Bureau of Mines, however. The contract objective is outlined later. IIT Research Institute has done pioneering work in high pressure jet development in the United States.5-8 Similar schemes have been investigated abroad. 9-13 Hydraulic mining of coal at relatively low pressures is successfully being done in the Soviet Union, Japan, Canada, and most recently, in Germany.

Jan 1, 1973

By Thomas J. Peters

The Lime Creek study area lies 100 air km east of Boise, and 70 air km northeast of Mountain Home, Idaho. The eastern boundary of the 28,000-hectare, east-west-elongate study area lies 0.2 km west of the 3,077-m-high Smoky Dome. The area is mainly underlain by Cretaceous granitoid rocks of the Idaho batholith. No mineral resources were identified, but two mines and one prospect were found in the study area. At the President and the Last Chance mines, in the southwest corner of the study area, gold mineralization occurs along steeply dipping east-northeast-trending faults and associated quartz veins, and within adjacent Cretaceous granitic rock. The mineralized material is not rich enough to mine underground, and near surface, open-pit-mineable deposit areas could not be identified. The third prospect, the Ventura, is within altered pink granite of probable Tertiary age, but metal concentrations are very low. Geothermal activity was not observed within the study area, but hot springs do occur in the Vicinity. Bedrock observed is only suitable for the most basic high bulk and low end value applications, such as crushed aggregate. Numerous sources for crushed stone occur closer to markets. Alluvial concentrate (placer) samples did not contain free gold, and no substantial alluvial bars were seen; deposits were too small to contain resources.

Jan 1, 1993

By K. C. Dean

During investigation of the occurrence of manganese deposits in the western United States, examining engineers of the Bureau of Mines collected samples from several properties in Montana. Extensive laboratory tests were made to determine the amenability of these ores to standard ore-dressing methods of concentration to produce marketable-grade products. The Tzarena claim, one of the properties sampled, is on the western end of the Rama or Black Chief vein in the city of Butte, Silver Bow County, Mont., on the southwestern periphery of the mining district. The Black Chief 'WAR system contains one of the largest and most extensive known rhodochrosite deposits in the world. Test work was conducted on two samples of Tzarena ore. Sample 1 is representative of a vain 5 feet wide on the 150-foot level of the Tzarena shaft. Sample 2 is representative of a vein 8 feet wide in the 100-foot level of the shaft. The Minnie Jane mine, 1/2 mile northwest of the Tzarena claim, contains ore similar in mineralogical composition to Tzarena ore but differing materially in manganese content and to some extent in physical characteristics. Ore-dressing investigations were made on three samples of Minnie Jane ore. Sample 1 represented stock-piled ore, sample 2 represented ore from Minnie Jane mine having a considerable sulfide content, and sample 3 represented low-grade ore.

Jan 1, 1951

By Leonard Obert

The investigation reported herein is concerned with the generation and propagation of the strain wave produced in rock by the detonation of a high-velocity explosive. This report is the second of a series that will deal with this and related problems. The rock type in which these experiments were carried out was greenstone. Subsequent reports will discuss similar investigations in other rock types. Specifically, the problem under study is concerned with how certain characteristics of the strain wave, such as the maximum compressive and tensile strain, the maximum time rate of change of strain, the frequency components present in the pulse, the duration of the pulse, and other measurable characteristics, vary with the size of the charge and the distance from the detonation point to the point of measurement. . Other investigators have studied certain aspects of the generation and propagation problem in rock. However, in these studies the travel distances from the detonation to measurement point were comparatively long and the frequency components in the explosive wave were usually under 100 c.p.s. In this study the detonation to measurement distance covered. the range from 2 to 54 feet, and the strain gages and recording equipment employed in the instrumentation of the problem had a frequency response range from 200 to 10,000 c.p.s.

Jan 1, 1950

By Phillip R. Moyle

A mineral survey of 19,350 acres of the Gooding City of Rocks Wilderness Study Areas (WSAs) in the north-central Snake River Plain was conducted by the U.S. Bureau of Mines in 1984. No formal mining districts are known in or near the study area. Forty-two placer claims within and adjacent to the study areas cover the Clover Creek diatomite deposit. Minor production from four pits was reported by the owners. The diatomaceous sediments are underlain by dacitic welded tuff and capped with basalt. Five exposures or blocks totaling 416 million tons of the diatomaceous material comprise the Clover Creek deposit; four of the blocks are in the study areas, out are predominantly covered by basalt. The North Clover block, just west of the areas, is only partially capped, and could be mined by open pit methods on the western flank of the exposure. The minable wedge contains an inferred marginal reserve of 35 million tons of diatomite possibly suitable for filter aid, filler, insulation, and other applications. At a production rate of 150,000 tons/year, total mining and milling costs for high-grade filter aid diatomite would be about $100/ton. The deposit is classed as marginal because products from this deposit may be inferior to currently marketed diatomite products. The market is well supplied by developed sources.

Jan 1, 1985

By H. Leitch

In laboratory experiments, the Bureau of Mines investigated melting, quenching, and sulfuric acid leaching of alumina from mixtures of albite and anorthite, and from anorthosites containing 26 to 32 percent alumina. Variations in pouring temperature, quenching and leaching conditions, were studied with respect to the extraction of alumina and impurities. Virtually all of the alumina was dissolved by leaching melted and quenched California anorthosite in boiling 16-percent sulfuric acid solutions for 15 to 30 minutes. The leach solutions were readily separable from the solid residue by conventional thickening and filtration techniques. Only 2 to 5 grams of SiO2, Fe2O3, or CaO dissolved per 100 grams of alumina. The quantity of SiOz in solution varied inversely with the duration of the leach and with the concentration of the H2SO4 solution used. Melted and quenched Wyoming and Minnesota anorthosites with SiO2:CaO weight ratios of 4.3 and 3.2, respectively, were less amenable to sulfuric acid leaching than California anorthosite with an SiO2:CaO weight ratio of 5.3. However, excellent results were obtained on the Wyoming and Minnesota anorthosites by the addition of SiO2 to these materials before melting, in quantities sufficient to adjust the SiO2:CaO weight ratios of the furnace charges to between 4 and 6.

Jan 1, 1966

By Laurance L. Oden

The Bureau of Mines conducted corrosion tests of 18 commercial alloys in H3 P04 -phosphate rock or A1,03 slurry, in 10 pct HF, and in 25 pct H2 SiF6 to simulate three environments anticipated in a Bureau process to extract fluoride values from phosphate rock. Small alloy coupons were rotated in duplicate tests at 4.4 to 21 fps in the slurry at 170° C to determine rates of erosion-corrosion. At 4.4 fps the lowest rates, in mils penetration per year (mpy), were measured for Hastelloy C-276 (<20), Hastelloy B (30), and Inconel 625 (150);the rates increased at 21 fps to 55 mpy, 45 mpy, and 1,000 mpy, respectively. The corrosion rate for all alloys exceeded 40 mpy in either the equilibrium vapor or liquid phases of aqueous solutions containing 10 pct HF or 25 pct H2SiF6 at 100° C. Uniform corrosion in 10 pct HF at 50° C was observed only for Inconel 625 (22 mpy), Hastelloy C-276 (43 mpy), and Illium 98 (17 mpy). Inconel 625 (0.75 mpy), Hastelloy C-276 (1.3 mpy), Illium 98 (1.7 mpy), and Incoloy 825 (0.45 mpy) were attacked uniformly in 25 pct H2SiF6 at 50° C.

Jan 1, 1974

By L. C. Brichta

The Tri-State zinc-lead catalog, compilation of which was initiated by the Bureau of Mines in August 1949, is designed to provide a continuing record of avail-able drill-hole logs and maps of mine developments in the zinc-lead district in southwestern Missouri, southeastern Kansas, and northeastern Oklahoma. The maps and data thus preserved constitute a reservoir of factual information readily available to individuals and firms interested in planning mineral explorations, to Government agencies for formulating estimates or ore reserves, and to the mining industry in the district for general uses. The areas to be included in the catalog embrace the explored and mined tracts within 760,000 acres of the more active western part of the district. The consensus among local mine operators, geologists, and mining engineers is that over 100,000 boles, costing more than $30,000,000, have been drilled in the district. Records of some of the early drilling and mine developments are destroyed or lost, but the Bureau of Mines has copies of about 47,500 drill-hole logs and is accumulating and recording on microfilm those that are currently available. As of May 1, 1954, the logs of approximately 28,000 drill holes had been microfilmed and are available for inspection at the Bureau of Mines office, Joplin, Mo.

Jan 1, 1955

By d&apos, Dennis V. Andrea

The Bureau of Mines and El Paso Mining and Milling Co. conducted a cooperative in situ leaching research program at the Emerald Isle mine near Kingman, Ariz. The objective of this research was to develop in situ leaching methods for 200,000 tons of ore exposed in the pit bottom and also 3,000,000 tons of ore under 200 feet of overburden adjacent to the pit. The research included core drilling for fragmentation analysis, inplace permeability testing, seismic surveys, blasting tests, blast vibration measurements, inplace leaching, and ground water monitoring. A l5,000-ton test area in the pit bottom was blasted and leached inplace for 117 days. This successful test was followed by leaching 100,000 additional tons of unblasted pit bottom ore. Two test blasts, under 205 feet of overburden and extending to 290 feet, were detonated in an area near the open pit. The second blast was detonated because the first blast did not create adequate permeability for leaching. Pit bottom leaching was discontinued and the test area under 200 feet of overburden was not leached because the company terminated operations at the Emerald Isle mine. Based on the research completed, an expanded in situ leaching system was designed, but not implemented, to recover copper from a 1,500,000-ton area at the Emerald Isle mine.

Jan 1, 1977

By Edward L. Tullis

Numerous widely distributed pegmatites of the southern Black Hills of South Dakota contain small amounts of beryl, and two minor deposits are known in the northern Black Hills. Few mines have produced more than 50 tons, and the current, rate of production for the area is about 100 tons annually. Total production, since the first records, is 2,358 tons. Most of the deposits contain less than 1 percent beryl, although the beryl zones in several deposits contain 2 percent beryl or more. Estimated reserves of beryl total 11,824 tons, and an additional 234 tons has been measured; there are other unestimated reserves. The pegmatites are in a belt about the margin of the Harney Peak batholith in the southern Black Hills, although they fail into three districts. The most important, from the point of view of production and reserves, is the Keystone district. Many deposits also are found in the vicinity of Custer and Pringle. Small amounts of beryl occur in the dikes near Hill City. A little beryl has been produced from the Tinton district in the northern Black Hills, and an undeveloped dike has been discovered on Whitewood Peak near Deadwood. The beryl-bearing pegmatites are principally coarse-grained intergrowths or massive segregations of feldspar, quartz, and mica. Some of them contain notable amounts of lithium minerals, as well as some tantalite, columbite, and cassiterite.

Jan 1, 1952

By Robert H. Merrill

A method of determining the strength of a mine roof layer in place is described in this report. The method was tested on a limestone roof layer 50 feet wide, 100 feet long, and 20 inches thick. In place measurements were accomplished by introducing air under pressure into a separation between the layer and the overlying roof, and as pressure was increased, the corresponding strain and deflection of the roof layer were measured until the roof failed. The ultimate strength of the roof agreed with the tensile strength of the roof rock (modulus of rupture) as determined in the laboratory; the modulus of elasticity as measured in place did not agree with the laboratory-determined values; the deflection and tensile strain in the layer in place showed good agreement with the theory of a body-loaded beam clamped at both ends. This procedure for determining the strength of a mine-roof layer is safer and less costly than successively widening a roof to failure. For example, it would have been necessary to mine the room to a width of 114 feet and a length of 228 feet to produce failure in this roof layer. The method is not necessarily limited to limestone; any thinly bedded rock type can be tested by this procedure when there is an open parting over the mined area.

Jan 1, 1958

By F. K. McIntosh, L. A. Dahmers

"INTRODUCTION North Carolina has been the leading producer of mica in the United States, accounting for roughly 50 percent of the Nation's output. The producing area is a belt some 100 miles in width lying in the Mountain and Piedmont sections in the western part of the State. Ashe, Watauga, Avery, Mitchell, Yancey, Buncombe, Haywood, Jackson, Macon, Transylvania, Rutherford, Cleveland, and Lincoln Counties supply the bulk of production, while small amounts have been produced in Gaston, Catawba, Burke, Wilkes, Yadkin, Stokes, and Person Counties.To assist the operators and expedite the production of mica during the recent emergency, the Bureau of Mines drilled four of the more promising mica properties in this State. The results of this exploratory program are recorded in this report.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Division, L. B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, O. C. Ralston, chief, analyzes samples and makes beneficiation tests."

Apr 1, 1948

By Wallace W. Roepke

The Bureau of Mines studied the cutting characteristics of point-attack bits to reduce airborne respirable dust and energy during cutting. Linear cutting of two coal types using four bit types at three depths of cut with three space-depth ratios was performed with a modified horizontal milling machine using an optical particle-size monitor for respirable dust sampling. The cutting action of one bit on a rotary hardhead mining machine was mathematically analyzed and compared with the results of the linear cutting test. Airborne respirable dust per unit mass cut (specific dust) was found to be a monotonically increasing function of specific energy. Specific dust and energy decrease with increasing depth of cut. The amount of nonairborne respirable dust was 100 to 1,000 times greater than the airborne dust. The plumb-bob bit produced the most airborne respirable dust and the highest specific energy of the four bits tested. Rotary cutting was a greater dust producer and energy consumer than linear cutting because of the constantly changing depth of cut, space-depth ratio, and attack angle of the bit relative to the horizontal bedding planes. A new cutting technique is proposed to minimize the existing problems of the rotary cutting machines by providing greater production, reduced dust, and minimized methane ignition potential at the face.

Jan 1, 1976

By Xavier B. Starnes

The Dike and Eaton veins in Crittenden County, Ky. (fig. 1), are along northwesterly trending relief fractures that lie between two northeastward striking major faults - the Moore Hill and- the Levias, in Crittenden County, Ky. The veins contain small, narrow, irregular ore bodies of fluorspar with subordinate quantities of sphalerite and galena. Gravel fluorspar was found on the surface in the Eaton vein, and open-cut mining was in progress on the W. M. Conyer property about 1900. Discovery of fluorspar in the Dike vein came much later, about 1933, on the W. H. LaRue tract, but the principal production on the Dike vein started after the discovery of gravel spar in 1938 on the land of the P. J. Gilless estate. Production from the Eaton vein was estimated at 9,400 tons and that from the Dike vein at 15,700 tons, a total of 25,100 tons. A large part of this production was gravel fluorspar from within 50 foot of the surface. Beneath the gravel spar the veins are very narrow, averaging 2 to 2.5 feet in width, and the ore shoots are small. The deepest mine level was 140 feet below the surface, and the deepest shaft 150 foot. Orb was concentrated by log washer or sent unwashed to custom mills at Marion, Ky. about 6 miles distant.

Jan 1, 1950

By Sean Gallagher

The restricted workspace present in low-seam coal mines forces workers to adopt awkward working postures (kneeling and stooping), which place high physical demands on the knee and lower back. Method: This article provides an analysis of injury claims for eight mining companies operating low-seam coal mines during calendar years 1996-2008. All cost data were normalized using data on the cost of medical care (MPI) as provided by the U.S. Bureau of Labor Statistics. Results: Results of the analysis indicate that the knee was the body part that led in terms of claim cost ($4.2 million), followed by injuries to the lower back ($2.7 million). While the average cost per injury for these body parts was $13,100 and $14,400, respectively (close to the average cost of an injury overall), the high frequency of these injuries resulted in their pre¬eminence in terms of cost. Analysis of data from individual mining companies suggest that knee and lower back injuries were a consistent problem across companies, as these injuries were each among the top five most costly part of body for seven out of eight companies studied. Application/Impact: Results of this investigation suggest that efforts to reduce the frequency of knee and low back injuries in low-seam mines have the potential to create substantial cost savings.

Jan 1, 2009

By Margaret R. Lickes

Mercury was produced originally at the Idaho Almaden mine from 1939 to 1942. When the ;.nine was shut down, more than 100,000 tons of ore, containing from 2.5 to 3 pounds of mercury per ton, was known to be adjacent to old workings but had been considered too low grade for commercial operation. Later, detailed, systematic exploration by Rare Metals Corporation of America increased and delimited enough minable reserves for further operation to be foreseen for several years. The average grade of the ore is estimated at slightly more than 3.5 pounds of mercury per ton. Open-pit mining and installation of the largest rotary kiln in the United States furnacing mercury ore have made possible profitable exploitation of these reserves (fig. 1). The bulk of the exploration was by percussion drilling, although some diamond drilling was done to check the results. When enough reserves were indicated to assure a successful operation, stripping and plant construction were started simultaneously. Figure 2 is a general view of the plant. The ore bodies, although irregular in size, shape, and grade and covered by essentially barren cap rock, are amenable to low-cost, trackless, open-pit mining. Development consists of stripping the overburden and removing, barren cap rock. Ore is being mined at approximately [5],000 tons per month and treated in a 175-ton-per-day furnacing plant.

Jan 1, 1957

By James C. Barker

Alluvial cassiterite concentrations are widespread in river gravel and high level terraces within the Ray River watershed. The area lies in unglaciated terrain of Alaska&apos;s northern interior. Cassiterite originates from several calc-alkaline plutons of the Ruby batholith. Extensional stresses resulted in graben-like Tertiary basins that were flooded by a 200 ft thick section of mid-to late- Tertiary basalt flows. Basalt blocked local drainages, and 50- to 100-ft of terrace gravel was eventually deposited on top of the flows. Further downwarping and eventual fluvial downcutting of the flows resulted in cycles of accelerated sediment transport, deposition, and reconcentration. Repeated erosional cycles concentrated heavy minerals and resulted in development of tin placers. Preliminary resource estimates of contained tin in Recent alluvium range from 62 to as much as 172 million lbs-Sn in 300 million yd3. Grade of about 90% of the gravels is estimated to range between 0.2- to 0.5- lbs-Sn/yd3. Associated gold and rare earth elements (REE) in monazite and xenotime may be recoverable. Most of the tin is considered a subeconomic inferred resource, though, at least some of the gravels contain 2-to 6-lbs-sn/yd3. Estimates are projected on the basis of surface sampling and several auger drill holes and are provided for the purpose of land-use management planning.

Jan 1, 2011

By P. R. Tisot

Knowledge acquired from this research contributes to a better understanding of the physical structure of Green River oil shale and provides fundamental data and concepts that may serve to improve oil-shale technology. This study by the Bureau of Mines indicates that oil shale is a highly consolidated organic-inorganic system with no significant micropore structure, pore volume, or internal surface. This system is a form of physical structure that precludes rapid diffusion of either gases or liquids. The mineral matter consists essentially of nonspherical particles that tend to follow a log-normal size distribution. An excess of 99 weight-percent of these particles have equivalent spherical diameters of less than 44 microns--75 weight-percent are from 2 to 20 microns, and 15 weight-percent are less than 2 microns. The surface area (3 to 5 square meters per gram) of these mineral constituents is mainly external surface. The mineral constituents contain some micropore structure--pore radii ranging from 10 to 100 Angstrom--with the pore sizes randomly distributed. Distribution of the organic matter within the inorganic matrix is essentially interparticle and not intraparticle. The organic matter within the micropores of the mineral constituents is less than 4 percent of the total. Estimates made from surface area data suggest that perhaps only a small amount of the organic matter is bonded either physically or chemically to the mineral constituents.

Jan 1, 1963

By C. H. Schack, K. C. Dean

An investigation was made to devise and evaluate a flexible flotation method for beneficiating typical tactite types of calcareous scheelite - bearing ores ; these scheelite - bearing ores are available in large tonnages in deposits containing 0.2 to 0.3 pct tungsten trioxide . The objective was to achieve a high recovery of the tungsten in concentrates , containing a minimum of 10 pct WO3 , that would be suitable for chemical processing into high- quality synthetic scheelite . The principal problems encountered and resolved by bench- scale flotation tests on ore samples from five different deposits were to define the conditions and reagent combinations essential for ( 1 ) achieving selective flotation of a small amount of scheelite from a large amount of calcite and ( 2 ) controlling the effect of small amounts of calcium , magnesium , and iron salts in the ores and water used . The flotation process was evolved from batch tests and continuous runs in a pilot - scale mill with a capacity of 100 lb per hour . The flotation process comprised ( 1 ) removal of sulfide minerals , ( 2 ) conditioning the residual ore pulp with sodium carbonate , quebracho , and trisodium phosphate , and ( 3 ) rougher flotation and single - stage cleaning of a scheelite concentrate . In a pilot plant run , over 91 pct of the tungsten was recovered from ore containing 0.27 pct WO3 , in a concentrate containing 11.2 pct WO3 .

Jan 1, 1964

By K. A. Johnson

Marshall and Bird have published the results of a cooperative investigation by the Bureau of Mines in which they developed a procedure for measuring the agglutinating value of coal.4 As stated in their paper, the procedure outlined was suggested by the early worn of Richters5 and Campredon,6 whose procedures were hurriedly modified to meet the need of an investigation then in progress. Since the publicatien of that paper, further work has been done in an attempt to show how the variables involved affect the concordance of the results, in order that such results may be obtained in different laboratories. Briefly, Marshall and Bird&apos;s method for determining the agglutinating value of coal consists in carbonizing an intimate mixture of 10 parts by weight of sand and 1 part by weight of coal in a porcelain crucible at a uniform temperature of 950° C. in a, vertical, cylindrical, electrically-heated furnace. After carbonization, the resultant buttons are crushed in a testing machine and the breaking strengths recorded in grams. The agglutinating value reported is the average breaking strength of 10 buttons. The coal for the test is prepared by crushing to pass a 100-mesh screen. The sand used as a diluent is sized between 40 and 50 mesh sieves with openings of 0.381 icon and 0.279 millimeters, respectively.

Jan 1, 1930