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By Potter G. M.

Ore-dressing tests were conducted on a sample of ore submitted by the Richmond Hill Mining Co. of Lead, S. Dak. as a part of the Bureau of Mines program for investigating potential domestic sources of manganese. Half of the sample was taken from the 300-foot level and half from surface cuts. The problems involved were liberation and rejection of silica and iron and removal of lead, Silver, and gold from the manganese concentrates. Although a portion of the silica and iron oxides was too intimately associated with manganese minerals for rejection by ore-dressing methods, thus limiting recovery of high-grade concentrates, the Richmond Hill ore was found amenable to simple gravity methods of concentration for producing intermediate-grade products. By jigging and tabling, 73.8 percent of the total manganese was recovered in a product that, when sintered, assayed plus 40 percent Mn. Lead, silver, and gold were successfully removed from gravity concentrates by a chloridizing roasting treatment.

Jan 1, 1948

By Thomas Fraser, M. G. Driessen

This report is one of a series written by members of the Solid Fuels Mission to Germany describing wartime developments in the mining , preparation, and utilization of coal . The mission was organized early in 1945 under the auspices of the Technical Industrial Intelligence Committee , which cooperated with a counterpart British Committee . Engineers from other allied countries cooperated in some of the investigations . The Solid Fuels Mission operated under the direction of a steering committee headed by Dr. C. J. Potter , deputy solid fuels administrator . The personnel of the mission consisted of H. F. Yancey , in charge , J. W. Buch , Thomas Fraser , L. L. Newman , and L. D. Schmidt , of the Bureau of Mines ; H. H. Lowry , Director of the Coal Research Laboratory , Carnegie Institute of Technology ; H. J. Rose , vice president and director of research , Bituminous Coal Research, Inc .; and F. H. Reed , chief chemist , Illinois Geological Survey . Over 50 reports were written by the members of the Solid Fuels Mission . These and microfilms of supporting data obtained in the course of the investigations are on file at the Bureau of Mines , Washington , D. C. where they are available for public examination . The Office of the Publication Board in the Department of Commerce is prepared to furnish photolith copies , photostats , or microfilm reproductions of all declassified reports . A Bibliography of Scientific and Industrial Reports is issued weekly by the Department of Commerce , Office of the Publication Board , and is sold by the Superintendent of Documents , Government Printing Office , Washington 25 , D. C. , on a subscription basis . An initial payment of 10 dollars will provide for approximately 9 months , and subscribers will be notified when additional remittance is necessary . All subscriptions will begin with volume 1 , No. 1 , unless ordered otherwise . The Bibliography covers all materials and subjects and gives instructions for obtaining the desired items . The reports of the Solid Fuels Mission relate to the following general subjects : Mining methods in the Ruhr district of Germany , with special reference to mechanical cutting and loading equipment , pneumatic packing , and Diesel mine locomotives ; activities of industrial research laboratories supported by the German coal and coke industry ; coal preparation in western Europe ; low-temperature carbonization processes ; metallurgical coke from weakly coking coals ; low- ash electrode carbon from coal ; new developments in the production of metallurgical coke and the utilization of gas and byproducts ; briquetting brown coal and bituminous coal without the use of binders ; recent engineering developments in gas turbines and steam generators , with special reference to use of coal ; German coal-fired heating and cooking stoves; and the commercial extraction of coal with solvents for production of synthetic liquid fuels or chemical products . Numerous reports on the activities of German synthetic - liquid -fuels plants and the plants for the production of synthesis gas from solid fuels are available in the same office as the Solid Fuels Reports . It is planned to publish in this series of Information Circulars the more important reports or combinations of reports prepared by the members of the Solid Fuels Mission . A similar series on synthetic - fuel activities is being prepared .

Nov 1, 1946

By H. W. Kilau

The Bureau of Mines evaluated synthetic fluorspars as substitutes for natural fluorspar in basic oxygen steelmaking using a high-temperature rotational viscometer and a quarter-ton basic oxygen furnace (BOF). Consider-able variation in stability and BOF slag fluidizing properties were found when using the initial synthetic products, but improved synthesis methods produced synthetic fluorspars that were generally comparable to natural fluorspar in laboratory testing. Trials in the furnace showed the synthetic products to be operationally the equivalent of natural fluorspar. Higher sulfur and phosphorus contents in some of the synthetic materials did not adversely affect the steel chemistry. Analyses of wet scrubber samples showed evidence that the pelletized synthetic fluorspars experienced greater physical and chemical disintegration than did natural fluorspar. It was also found that operation of a BOF without fluorspar is possible when making low-carbon steels because iron oxide is intrinsically generated as the slag fluidizer.

Jan 1, 1981

By S. J. Rodgers

MSA Research Corporation, Division of Mine Safety Appliances Company, was awarded a contract to conduct a survey of past and present methods used to control respirable dust in noncoal mines and ore processing mills. The survey covered information reported in mining journals, and U.S. Bureau of Mines Circulars, dust inspection reports, on-site evaluation of dust control methods and systems, and contact with manufacturers of dust control equipment. Both surface and underground mining operations were visited. Fifty mines and 51 processing plants were included in the survey. Dust control methods for the following types of ores or mines were studied: [ ]

Jan 1, 1974

By D. Harrington

Springing or chambering of deep drill holes is common practice in some quarries. It involves definite hazards from premature explosion during placing of the springing charges or the final charge due chiefly to heating of the bottom of the holes by the successive exploding of the springing charges or, in some instances, from burning of paper or other material following detonation of the explosives The danger is either unknown or disregarded in many instances by those who place the charges in the holes. Disregard of this hazard probably is, at least in part, responsible for the far too high fatality and injury rate due to charging explosives and premature slots in quarry work. Awareness of the danger' should result in elimination or at least of material decrease in injuries from this cause.

Jan 1, 1941

By E. K. Stanek

This report contains the results of an investigation into the feasibility of periodically measuring parameters of the insulation for a mine electrical power system in order to detect incipient faults. The variety of insulation parameters evaluated included insulation resistance, dissipation factor, power factor (vs. applied voltage), current harmonics, leakage current, infrared radiation, as well as certain circuit breaker parameters and tests. In order to augment field tests a program of accelerated life testing was also carried out. Apparent inconsistencies in data were identified as the result of environmental effects, primarily temperature and relative humidity. A series of environmental tests were conducted to develop correction factors that allow one to refer measured parameters to standard conditions. A portable data collector was develop-ed to aid in the accurate collection and analysis of laboratory and field data. The primary conclusion is that insulation deterioration can be measured and failure predicted with reasonable confidence. The secondary conclusion is that most of the tests are impractical in the field although useful in the laboratory. Infrared sensing, insulation resistance and dissipation factor are the best insulation field tests when portability is taken into account.

Jan 1, 1979

By D. A. Paice

A portable calibrator to check tie trip setting of dc circuit breakers within an accuracy of +5% has been developed for the Bureau of Mines. It operates from a 300 volt dc trolley wire to provide controlled current pulses of 120 milliseconds duration and continuously adjustable from 1400 to 3600 A. These current pulses enable a breaker dc trip current to be determined and subject the contacts to full current rating. The equipment is simple to use and weighs 86 pounds. Connections are made with protected, clamp-on leads which are separately connected and weigh about 22 pounds. An accurate calibration procedure takes less than 5 minutes to complete.

Jan 1, 1978

By V. E. Edlund

Pyrometallurgical studies by the Bureau of Mines demonstrated the feasibllity of sintering and smelting a low-grade flotation concentrate made by pilot-plant processing 10-percent manganese ore from the Maggie Canyon deposit, Mohave County, Ariz. Under optimum conditions 85 percent of the manganese in a flotation concentrate that assayed 36 percent manganese was recovered as standard ferromanganese. A blend of this flotation concentrate with high-grade dithionate pilot plant precipitate was similarly processed with a recovery of 90 percent of the manganese. Thorough mixing and pelletizing of the charge before treatment on the sinter hearth was necessary to produce a well agglomerated product by single pass sintering. Although satisfactory sinter was produced from a variety of material combinations, best results were obtained on a charge that contained 80 percent flotation concentrate and 20 percent return sinter fines. This combination was mixed with 6 percent coke, based on weight of concentrate; and 12 percent moisture. Sintering such a charge yielded a well agglomerated product containing over 80 percent coarse material, The results of standard crushing tests showed that the product was physically comparable to iron ore sinters and manganese nodules.

Jan 1, 1962

By Mulligan John J.

The Bureau of Mines investigated lode tin deposits on Potato Mountain, Seward Peninsula, Alaska. Tin was found to occur as cassiterite associated with quartz, tourmaline, pyrite, arsenopyrite, and earthy clays, but the deposits lack the varied accessory minerals commonly found in tin districts. The tin-bearing deposits are in metasediments along minor breaks and bedding planes but not in the crushed earthy filling of major faults. Cassiterite and sulfides occur with quartz in veins, both with and without earthy clays, and disseminated through tourmalinized wall rocks. The deposits are characterized by irregular segregations containing 1 to 10 percent tin within zones averaging not over 0.25 percent tin. The largest segregation exposed is on the summit of a low hill on the east-central slopes of Little Potato Mountain; most of the outcroppings are in an area trending east to west, roughly 10 to 30 feet wide and 300 feet long. Sample values ranged as high as 12 percent tin, but the average grade may be about 1 percent tin. The extreme irregularity of both grade and composition precludes a more exact determination. Similar concentrations are scattered for over 1,000 feet to the west and north, but these are smaller and lower in grade. Elsewhere on Potato Mountain, generally similar deposits occur as clusters of veinlets at widely separated points in the metasedimentary walls of major faults.

Jan 1, 1965

By Russell R. Trengove

The Strawberry tungsten mine is in the Jackass Mining District, in an isolated portion of eastern Madera County, near the southeast corner of the Yosemite National Park. The deposit was discovered in 1941, and production started in 1943 when the mill was completed. With the exception of 1946 and 1947, production has been continuous. The area in the vicinity of the mine is granite containing islands of sedimentary beds highly altered by metamorphism that resulted from the intrusion of acid igneous rock. Schoelite occurs in almost vertical lenses of tactite between the limestone and the granite.

Jan 1, 1949

By Fred D. DeVaney

Copper sulphate is a common flotation reagent for blonde ores. Metallic iron also is present in the mill circuit, and a reaction between the iron and the salt would be in accord with well-known chemistry. The abundance of metallic iron in a flotation food may be noted by even perfunctory examination. First of all the mine contributes metallic iron, then the coarse-crushing machines add their share, and finally the fine-grinding medium its portion. If the grinding is with cast-iron balls the amount of metallics is greater than when steel is used. Thus it, is that much more metallic iron is present than would be indicated by noting the ball consumption. An estimate that the total amount of metallics is twice that supplied by the balls and liners might not be far amiss. That copper sulphate plates out on iron in an acid solution is well known, but since flotation is practiced commonly in solutions where acid has not been added this reaction has not been given sufficient thought.

Jan 1, 1929

By James P. Bennett

To identify construction materials for emerging technology in chemical and metallurgical processes, the Bureau of Mines investigated the acid resistance of ceramic materials. Eight commercial ceramic materials comprising two red shale, two fire clay, a silica, a five-claybonded silicon carbide, a carbon, and a high-alumina brick were evaluated. Samples were exposed for 110 days to 20 wt pct HCl at 50°, 70°, and 90° C and to 30 wt pct HCl at 70° C. Statistically significant changes in cold crushing strength, volume, and weight were generally small or not detected. The leach rates of Al, Ca, Fe, K, Mg, Na, Si, and Ti ions were monitored. The carbon brick sample had the best acid resistant properties with a maximum total leached ion weight loss of 0.004 wt pct. The silicon carbide, the silica, and one of the fire clay bricks also had excellent acid-resistant properties.

Jan 1, 1983

By John A. Kost

Control of the dust produced by continuous mining machines in coal mines is conventionally attained by water sprays from fixed nozzles mounted on the frame of the machine behind the cutting head. In the tests conducted under this contract a so-called "wet-head" machine was used, where the spray nozzles were mounted on the rotating head itself, close to the coal-cutting bits. The tests were conducted at the Robena Mine of U.S. Steel Corporation, using Lee-Norse machines. Operating the wet-head machine and a conventional spray machine in turns in the same section, it was found that the wet-head produced approximately 25 percent less respirable dust and 60 percent less total airborne dust than the conventional spray machine. The wet-head also greatly improved the visibility of the cutting bits from the machine operator's position. Several difficulties had to be overcome before any meaningful tests could be conducted, including excessive pressure drops in the piping system and plugging of the nozzles from internal water contamination. The major obstacle, however, was the rotating water seals on the wet-head, which leaked excessively after only a few hours of operation. Only after several changes and plant and laboratory tests was a design found which permitted conducting the underground tests without appreciable water leakage.

Jan 1, 1976

By Yael Miron

Two recent unplanned detonations occurred during blasting operations in sulfide-bearing ores in a Nevada gold mine. Other premature detonations have also reportedly occurred at other Nevada, California, and Arizona operations within the past few years, with increasing frequency. Unplanned or premature detonations can be extremely hazardous to life and can cause extensive property damage. A miner was injured in one of these occurrences. This report, by the U.S. Bureau of Mines, is intended to acquaint personnel involved in such mining activities with the basic causes for these accidents. These causes include the exothermic oxidation of pyrite (FeS2) and formation of ferrous sulfate (FeS04), the exothermic and energetic reaction of the ferrous sulfate with ammonium nitrate-fuel oil (ANFO)-based explosives, and the associated elevated temperatures that can set off detonators and explosives in the boreholes. Recommendations for safe operation by the Mine Safety and Health Administration, the Bureau, and the mine involved with the recent incidents include monitoring temperatures in the blast holes, analyzing for sulfate and ferrous ions, and limiting the time between loading and firing in accordance with conditions in the blast holes. Other procedures for safe operations should fit specific conditions in, the mines.

Jan 1, 1992

By Brian G. White

The Coeur d'Alene Mining District of northern Idaho is remarkable for its number of large ore bodies and for the amount of its historical production of lead, zinc and silver (Fig. 1). Since veins were first discovered in 1884, more than 127 Mt (140 million st) of ore have been produced from narrow, high-grade veins. Mining continues at the Lucky Friday, Galena and Sunshine mines (Fig. 2). All have been in production for decades. At these mines, more efficient mining and exploration techniques have reduced costs while adding significant new reserves. Even the old Bunker Hill Mine, where ore was first found in 1875, continues operation on a limited basis, partly involving production of world-class pyromorphite specimens. Until recently, the Coeur Mine was also a profitable silver producer. Other large producers have included the Star-Morning, Hecla, Page, Standard-Mammoth, Hercules and Gold Hunter mines (Fig. 2). The first deposits were discovered by prospectors who spilled over from the Murray gold mining district, 24 km (15 miles) to the north. The Bunker Hill Mine was founded the year after the first veins were discovered. Bunker Hill has now operated for more than 100 years. Production includes 2.3 Mt (2.6 million st) of lead, 1.1 Mt (1.2 million st) of zinc and 4.1 kt (132 million oz) of silver. Total district production through 1996 (Springer, 1997) amounted to 7.3 Mt (8.1 million st) of lead, 3 Mt (3.3 million st) of zinc, and 34.5 kt (1.109 billion oz) of silver. This record establishes the district as the largest recorded producer of silver in the world, while also yielding major quantities of lead and zinc. Only Potosi, Bolivia, may have produced more silver, although records are unclear. Despite the district's longevity, historic production and current activity, the published literature on the district lags behind with regard to recent concepts of district geology. The most recent comprehensive US Geological Survey (USGS) bulletins (Hobbs et al., 1965; Fryklund, 1964) are dated. Much research in the last half century has been short-lived or geographically restricted because the district is large and its geology is complex - and even this research tends to remain unpublished. Thus, it has been difficult for in- [ ]

By E. C. Pattee

A mobile spectroscopic laboratory was completed by the Bureau of Mines in 195 to provide a rapid, inexpensive means of field testing samples for beryl¬lium and other associated metals of possible commercial importance. Spectro-copes have been used in laboratories for many years in various types of research and routine analyses, but this spectroscope is probably the first mobile unit. The laboratory provides for spectroscopic, radioactivity, fluorescent, and limited chemical tests of samples. The unit has been a valuable reconnaissance tool. It has been used to search for beryllium, cesium, columbium, tantalum, rubidium, and lithium in Idaho, Washington, and Montana. Several very low grade deposits of these elements were found, and occurrences of other important elements were identified; however, none are of economic importance. The spectroscope permits the detection of elements by analysis of visible light produced when elements in a small powdered sample are volatilized in an electric arc., A total of 70 elements can be detected; 29 can be detected at or below 0.01 percent, Electric power for the arc is supplied by a gasoline motor-driven generator, Equipment is housed in an aluminum van, mounted on a 4-wheel-drive vehicle for easy maneuverability on mountain roads, A trailer with crushing, pulverizing, and splitting equipment permits the reduction of samples to a small representative pulp.

Jan 1, 1963

By Gregory J. Chekan

The Bureau of Mines, in an effort to improve planning and development in coal mining, is investigating strata interactions associated with mining of multiple coalbeds. Two common interactions that occur between adjacent coalbeds are subsidence and pillar load transfer. The study described involves underground observations and measurements conducted at two Pennsylvania mines, each affected by one of these interactions. At the mine affected by subsidence, measurements show that undermining had little effect on upper mine pillar stability, but had a more severe effect on the development and maintenance of entries. Roof-to-floor measurements recorded over four times more convergence in entries developed over gob as compared with entries developed over support pillars in the lower mine. At the mine affected by pillar load transfer, Initial in situ measurements have shown the existence of a pressure arch in the lower workings. Prior research has shown that arch interaction between two adjacent openings can create stress concentrations in the in-nerburden. Underground measurements and results obtained from both mine sites correlate with theoretical and photoelastic multiple-seam models, and eventually these field data will serve to refine model accuracy. Further study of multiple-seam interaction mechanisms will lead to improved mine planning, increased resource conservation, and a safer working environment.

Jan 1, 1986

By Frank D. Lamb, Lloyg H. Baning

"The crushed-stone industry has long been troubled with the problem of producing a more or less cubical product for use as concrete aggregate. Its seriousness varies widely for each producer, depending upon the character of the rock employed for raw material and the ultimate use of the crushed stone. For many construction uses, such as the macadam or bituminous-concrete- type road, flat pieces are not objectionable and may even be preferable to more cubical rock. However, most specifications for concrete require that the stone must be reasonably free from flat and elongated pieces.The rigid specifications set by many contractors have resulted in the rejection of coarse aggregate that, except for the presence of an excessive amount of flat and elongated pieces, would be entirely acceptable. In many instances, if an efficient, economical method of removing flat and elongated pieces were available, local producers could meet the requirements of the contractor and thus eliminate the necessity for importing more cubical material.A brief investigation of the problem of removal of flat and elongated pieces from crushed aggregate, carried out at the Eastern Experiment Station of the Bureau of Mines, indicated that it is mechanically possible to remove flat pieces from crushed rock.TEST EQUIPMENTA number of mechanical devices are used by the coal industry for separating slate from coal; these depend upon the difference in shape of the crushed slate as compared with the coal. Such devices as shutter screens, spiral separators, and the Norman picker would be suitable for removing flat pieces from crushed rock in the same manner as they are used by the coal industry. None of these devices was immediately available for testing purposes, so an attempt was made to construct a simple device that could be used in commercial operations."

Sep 1, 1944

By William M. Knuth

The objectives of this study were the evaluation of the technical and economical feasibility of utilizing color and color infrared aerial photography to satisfy some informational needs for pre-mine planning, mine progress monitoring, and reclamation monitoring. Seven aerial data collection missions were conducted within a two year period over strip mine sites in Pennsylvania. Scales of 1:6,000; 1:12,000; 1:24,000; and 1:48,000 were flown on the first aerial mission. The 1:12,000 was chosen as the optimal scale for the remaining six flights. An extensive literature and legislative review and discussions with strip mine operators identified the informational parameters that could possibly be obtained from aerial photography. Interpretability accuracies were evaluated for parameters in the broad categories of land use, soils, water, vegetation, and geology. Seasonal interpretation characteristics were noted for infrared photography. Man hours for photointerpretation and costs of aerial data collection were monitored closely and incorporated into a cost benefit analysis. Those parameters that could be mapped, identified, or measured with accuracies =75 percent were incorporated into a photointerpretation training manual. An additional analysis was performed to determine the applicability of the interpretation methodologies and results developed for Eastern sites to Western surface coal mining sites. In addition, a separate aerial photographic interpretation manual was produced during this contract. It is intended to be utilized by eastern and midwestern surface mine operators and regulatory personnel.

Jan 1, 1978

By J. E. Miller

This paper reports experimental determinations by the Bureau of Mines of compressibility factors to 4,000 pounds per square inch absolute (p.s.i.a.) for helium at temperatures from -10° to 130° F. and for 16 helium-nitrogen mixtures at 70° F. This information is needed for computing accurate discharge volumes and is necessary for determining an average-density value for use in orifice-meter formulas. In thermodynamic calculations, several functions of the compressibility factor with pressure and temperature are required. The data in the original publications (6, 8)5 of this study have been reexamined and have been given a more comprehensive treatment. The recalculated compressibility factors are higher by approximately 0.2 percent because in the earlier work a linear relationship between the compressibility factor of helium and pressure was assumed.

Jan 1, 1961