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By Jennifer Riefenberg

The U.S. Bureau of Mines has long recognized the hazards associated with rock burst activity in underground mines. Concern over lost lives and resources prompted this study to further characterize rock burst occurrence as related to microseismicity and mining. A period of over 1,079 days of mining with 101 bursts, where microseismicity rates and blasting were recorded, was used in this study. Statistical analyses investigated relationships between (1) rock burst occurrence versus blasting, (2) rock burst size versus damage, (3) rock burst occurrence versus average micro seismicity rates, and (4) rock burst occurrence versus local mine geometry. Statistical analyses showed that 91% of all rock bursts occur with blasting while only 3% of all rock bursts occur, apparently, independent of blasting. Additionally, the long-term average daily micro seismicity rates appear to dictate when blasting will trigger rock bursts. Time series analysis on the daily microseismicity resulted in model equations that may be used to forecast the daily microseismic activity.

Jan 1, 2010

By Foster Fraas

This Bureau of Mines report describes a method for separating minerals at magnetic susceptibilities within the diamagnetic susceptibility range. The maximum feed rate varies directly with the square root of the lower limit of permissible susceptibility, while the lower limit of permissible susceptibility varies inversely as the square of the magnetic field strength. Minerals may be separated at particle sizes smaller than possible on conventional dry-type magnetic separators.

Jan 1, 1969

By R. C. Hickman

"INTRODUCTION The most productive area of the eastern Virginia pyrite belt lies to the north of the village of Mineral., in Louisa County. The largest producers of pyrite ore in the area were the Armenius, Boyd Smith, and the Sulphur mines.The Boyd Smith mine started production about 1890 and operated more or less continuously until 1922, when competition from the Gulf States and Spain closed the pyrite mines in Virginia. There are no reliable records of production or value of minerals produced.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the most effective utilization of our mineral resources to the end that they take the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, Oliver C. Palston, chief, analyzes samples and performs beneficiation tests.The project was under the immediate supervision of Mitchell H. Kline, chief, Raleigh Division, Mining Branch, Bureau of Mines.LOCATIONThe Boyd Smith property is reached from Mineral, Va., by traveling north on State Route 522 about 2-1/2 miles. An unsurfaced road, winding in a northwesterly direction, loads to the Boyd Smith headframe, which is about half a mile from State Route 522 (fig. 1). The tract comprises 181 acres."

Aug 1, 1947

By Robert P. Vinson

A sequential sampler, based on the Archimedes screw, has been developed by the Bureau of Mines. Its initial purpose was to collect air samples during tracer gas studies in underground mines. However, the basic concept can be applied to other sampling needs, including sampling of liquids. A prototype was built and successfully tested in the Bureau's Experimental Mine at Bruceton, Pa. The simple design makes the sampler inherently durable and low in cost.

Jan 1, 1976

By Steven W. Schmauch

The Ruby Mountains study area encompasses 75,615 acres managed by the U.S. Bureau of Land Management in Madison County, MT. A mineral survey was conducted by the U.S. Bureau of Mines and U.S. Geological Survey in 1984. Bureau of Mines personnel reviewed literature and county mining records, and examined prospects or mineralized areas to determine mineral resources. Geological Survey personnel evaluated the area by geochemical sampling and geophysical surveys. There are no organized mining districts and no current claims in the study area. Significantly mineralized quartz veins, shear zones, or talc bodies apparently do not exist within the study area. A small part of the Kelly Iron Deposit is inside, but dips away from the study area; the main occurrence is estimated to have 32 million tons of subeconomic resources that average 21 percent iron.

Jan 1, 1985

By W. W. Weller

This report provides low-temperature heat-capacity data and entropies at 298.15° K. for magnesium metavanadate (MgV206) and magnesium pyrovanadate (Mg2V207). The work completes low-temperature measurements planned for alkaline-earth vanadates; an earlier report dealt with calcium vanadates.4 No similar data for these compounds have been published previously. Free energy of formation values at 298.15° K. were derived by combination of the present entropy values with heat of formation data. MATERIALS The materials used in the measurements were portions of the samples described in a previous Bureau of Mines publication by King, Koehler and Adami.5 Methods of preparation, chemical analyses, and X-ray examinations are covered in this paper. The indicated purity of the samples was 99.9 pct.

Jan 1, 1962

By A. J. Barry

To determine the torque-load relationship for SIB-inch (nominal)-diameter roof bolts, the Bureau of Mines tested 5 makes of expansion shells and 2 types of bolts (regular and high-strength) in 2 sandstone and 2 shale mine roofs. Unused flat-steel bearing plates in as-received condition were used in these tests. The relationship between torque and load was found to be approximately 50 pounds of load per foot-pound of torque for both the regular and high-strength bolts. This relationship is valid up to 130 foot-pounds for the regular bolts and up to 175 foot-pounds for the high-strength bolts. A torque of 130 foot-pounds on a regular bolt will produce a load of 6,150 ± 1,910 pounds 90 percent of the time, and a torque of 175 foot-pounds on a high-strength bolt will produce 8,050 ± 2,750 pounds 90 percent of the time. Above these values, the torque-load relationship tends to be erratic due to binding between the bolt and plug threads. Binding causes excessive torque to be expended in producing torsion in the bolt rather than tension. This torsion adversely affects the yield load of the bolt. Therefore, the installed torques should not exceed the 130-and l75-foot-pound values. A statistical analysis of the data showed that the torque-load relationship was not significantly affected by the type of bolt or expansion shell unit but might have been affected by the type of rock.

Jan 1, 1956

By A. W. Henderson

This investigation was performed to develop chlorination methods for extracting tungsten from scheelite and from an ore concentrate containing a mixture of scheelite and wolframite. On a laboratory scale with proper temperature control using elemental chlorine, over 90 percent extraction of tungsten is achieved. Carbon and sulfur dioxide were studied as reducing agents. The effects of salts such as calcium fluoride and sodium chloride were studied as additives to increase extraction and to reduce impurities in the volatile tungsten chloride product. Sodium chloride reacts with ferric chloride to form a nonvolatile double salt; whereas the chlorides and oxychlorides of tungsten are volatile and consequently condense free of iron. Separation of tungsten from molybdenum from an equal molar mixture was successful by fractionally distilling the oxygen-free chlorides and by selectively condensing the oxychlorides. Yields of 60 and 80 percent, respectively, were achieved for separating the less volatile tungsten chlorides containing less than 0.5 percent molybdenum.

Jan 1, 1965

By John H. Scott

At the request of the Mine Safety and Health Administration, U.S. Department of Labor, the Bureau of Mines evaluated the model BT 300 C-D blasting machine tester, manufactured and distributed by Research Energy of Ohio, Inc. (REO), to determine whether the tester performed as stated by the manufacturer and responded satisfactorily to electrical faults introduced into the blasting machine circuit. Tester readings were recorded for 13 blasting machines and for 12 circuits constructed to simulate the electrical parameters of actual machines. The tester readings were acceptable for all of the blasting machines, although the switch position assigned to one machine produced an off-scale reading. The tester responded satisfactorily to the simulated circuits and detected serious voltage or capacitance faults when they were introduced. However, it did not respond accurately to certain resistance faults. Temperature tests were also made, and the tester performed equally well at temperatures of 20°, 42°, and 81° F. This tester was judged a useful accessory for field checking blasting machines for defective batteries and capacitors, despite its limitations. It is recommended that the tester manufacturer specify the lowest acceptable reading at which a blasting machine may be used and below which the blasting machine should be returned to the laboratory or manufacturer for maintenance.

Jan 1, 1981

By Kenneth M. Earl

In its investigation of deposits of strategic minerals, the Bureau of Mines did some diamond drilling at the Almedia deposit In an endeavor to find an additional source of supply of lead and zinc. It is reported that in 1816, lead and zinc minerals were found in the limestone quarries near the boundary line between Scott and Center townships. In an attempt to develop these minerals in paying quantities, an alit was driven for several rods into a bluff Just west of the present Almedia mine, This is believed to be the Web mine, mentioned briefly by Parker Cleaveland in 1816. In 1901 the Almedia mine was developed by an open cut and three shafts. The hoisting shaft at the time of drilling by the Bureau of Mines was sounded to a depth of 115 feet. A concentrating plant reportedly made shipments to Hamburg, Germany, for reduction. The deposit is in a somewhat slaty limestone. The ore occurs in a northeast fracture zone along the strike of the limestone and dips to the southeast. Old miners state that the ore appeared as large chunks of galena and sphalerite. In 1949, to investigate the downward extension of the oreshoot, the Bureau of Mines drilled four holes aggregating 1,126.3 feet.

Jan 1, 1950

By C. W. Smith

The Bureau of Mines conducted physical and chemical beneficiation studies on three samples of waste investment casting molds to devise a method to liberate and recover zircon. Rod mill grinding, autogenous attrition grinding, and caustic leaching were liberation methods inves-tigated. Flotation, gravity separation, and caustic leaching and sizing were recovery methods investigated. Flotation techniques produced con-centrates containing up to 74.2 pct zircon with a zircon recovery of 53.4 pct. Gravity concentration produced concentrates containing up to 98.6 pct zircon; however, recovery of the zircon was only 57 pct. Caustic leaching and sizing produced concentrates containing up to 98 pct zircon with attendant recoveries of 81 pct.

Jan 1, 1985

1. In 2003, a total of 258 metal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Metal mines were the smallest mining sector, comprising 1.8% of all mining operations.1 • Gold mines comprised 44.2% (n = 114) of all metal mining operations. Other common types of metal mines were iron ore (n = 29; 11.2%), copper ore (n = 28; 10.9%), and lead and/or zinc ore (n = 21; 8.1%). • Nevada had the largest number of metal mines (n = 48; 18.6%) followed by Alaska (n = 29; 11.2%).

Feb 1, 2005

By D. H. Chambers

The Bureau of Mines developed a process for producing high-purity zinc and tin by electrorefining from liquid amalgams. Commercial grade metals were dissolved in mercury to produce saturated amalgams at room temperature. Amalgams were also prepared by electrolytic transfer from soluble anodes of the metals to a mercury cathode. Amalgams formed by both methods were used as anodes in electrorefining cells to produce high-purity cathodes. Metal impurities, excluding mercury, were at levels of less than 5 ppm in zinc and 9 ppm in tin. Mercury content was about 2 to 10 ppm in zinc products, and this was effectively removed by heating the cathodes in a vacuum. Mercury was excluded from tin cathodes by pumping the tin electrolyte through tin turnings and controlling the cell temperature.

Jan 1, 1969

By B. J. Scheiner

Extraction of molybdenum from molybdenite ore by an electrolytic oxidation procedure was investigated by the Bureau o f Mines. Various parameters affecting molybdenum extraction, such as salt concentration, temperature, treatment rate, current density, and particle size, were studied. Molybdenum extraction of 95.2 percent was achieved on a laboratory scale from an ore containing 0.35 percent molybdenite. Corresponding power consumption was 24 kwhr per pound of molybdenum extracted with a base consumption of 4.5 pounds of sodium carbonate. Laboratory and pilot plant experiments are in progress on low-grade molybdenum concentrates containing rhenium and copper. Preliminary results indicate that molybdenum extractions in the 90- to 99-percent range and rhenium extractions of 93 to 99 percent can he obtained without appreciable oxidation of associated copper minerals.

Jan 1, 1972

By R. V. Ramani, V. T. Burgos, J. A. McClay

Introduction The Cost program was developed to provide the planning engineer with a tool to evaluate the cost implications of the technical mine design decisions. Direct costing methods are employed, where feasible, to provide greater detail and accuracy in the primary cost centers. Options have been provided in the cost computation, economic analysis, and output data subsystems to increase the flexibility of the system. Computer Program The program is written in Fortran IV for use in the IBM System 360/370 computers. i. Main - The main routine reads and stores input data from three sources, user input, Cost Data Library, and data transfer from the Master Design Simulator. Data is trans¬ferred to the appropriate subroutines, as they are called, by means of labeled common blocks. ii. Subroutine CSTCOM - is a data modification routine which computes the peripheral charges related to labor and supervisory costs. iii. Subroutine MANPWR - interrogates section data to determine the total labor and supervisory costs for each cost center. iv. Subroutine CAPCST - computes the total capital investment for each cost center, including the economic life and salvage value of each element. Capital costs are determined by user selection of quantities and models of equipment. Equipment costs are stored in the Cost Data Library for retriev-

Jan 1, 1975

By Green R. E.

The removal of silica from commercial iron oxide concentrates by dissolution with sodium hydroxide was investigated by the Bureau of Mines as a means for producing supergrade concentrates. The effects of strength of solution, temperature, and digestion time on the extraction of silica were evaluated using eight iron oxide concentrates. Silica extraction from the eight concentrates was enhanced by autoclave leaching in the temperature range of 150° to 250° C and varied from 70 to 95 pct depending on the concentrate used. Superconcentrates containing less than 2 pct Si02 and more than 69 pct Fe were made only when magnetite concentrates were leached in the autoclave. The investigation showed that it is not difficult to obtain a supergrade product if the gangue is mainly quartz.

Jan 1, 1973

By Homer J. Ballinger

The Rex mine is one of several zinc deposits in Ozark and Howell Counties, Mo. It is the second of these deposits investigated by the Bureau of Mines in an effort to demonstrate reserves of sulfide ore underlying the shallow carbonate ores from which the district's major production has come. The initial investigation was made during 1945-46 on the Alice mine, Ozark County, Mo.21 The investigation reported herein was conducted during 1947. The Rex open pit is about 250 feet long, 100 feet wide, and about 25 feet deep (average). Three caved shafts are evident in the bottom of the pit, but the extent of the workings from these shafts is not known. The Bureau of Mines drilled five churn-drill holes in and around the Rex pit to test the grade and the vertical and lateral extent of the deposit. Two of the holes indicate notable zinc mineralization ranging from less than 1 to more than 10 percent metallic zinc, but largely in the oxidized condition.

Jan 1, 1948

By P. J. Colbassani

Samples of mine atmospheres collected by Federal coal-mine inspectors during their inspections and investigations of coal mines, in accordance with provisions of the Federal Coal Mine Safety Act (66 Stat. 692; 30 U. S. C., sees. 451-483) are analyzed routinely by chemical methods at Bureau of Mines laboratories. When samples collected in open workings of nongassy coal mines at points not less than 12 inches from the roof, face, or rib contain 0.25 percent or more methane, the act requires the operator, during operation of such mine, to comply with the provisions of sec. 209, Title II, of the act, which pertain to gassy mines. The methane con-tents of such samples are determined by a physical method based on infrared absorption spectrometry to provide an independent check on analytical results obtained by chemical methods. This information circular describes the equipment and procedures used by the Bureau for determining low concentrations of methane in coal mine atmospheres by infrared absorption spectrometry. ACKNOWLEDGMENTS The authors are indebted to Dr. R. A. Friedel, Chief of Spectrometric Section, Branch of Coal-to-Oil Research, Bureau of Mines, for suggesting the analytical method and for furnishing valuable advice and assistance, and to J. A. Queiser of his staff for making exploratory measurements by this method; to Dr. M. G. Zabetakis of the Division of Explosives Technology for his assistance during the conduct of preliminary experimentation; and to L. B. Berger, Chief, Branch of Health Research, under whose guidance the equipment was procured and the work conducted.

Jan 1, 1958

By Russell. Paul L.

"INTRODUCTION Preliminary reports by Bureau of Mines engineers 3/ and by the Federal Geological Survey 4/ suggested that exploration would discover substantial reserves of minable ore in the Contact mine, Grant County, New Mexico. During February and March 1943, a sampling program was conducted on this property under the direction of the author. This was art of a general survey of the manganese districts of southwestern New Mexico.In its program of exploration 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 exploratory project as practicable soon as after its conclusion. The Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocer, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. S. Dean, assistant director. With respect to this report, special acknowledgment is due to C. H. Johnson, district engineer for New Mexico, and E. D. Gardner, regional engineer, and his staff, of the Central Region of the Bureau of Mines at the time of this work in 1943; also to Kenworthy, metallurgist at the Rolla. Mo., Laboratory of the Bureau of Mines, for work on beneficietion of the ore, and Sherman K. Neuschel, geologist of the Federal Geological Survey, for assistance in interpreting geological data at the project."

Oct 1, 1946

By E. C. Lane

Although motor gasoline marketed in the United States in January of this year was, on the average, slightly more volatile than that sold in January 1925, the improvement in quality is too small to be of importance. In other words, there is no evidence that any radical change in the quality of gasoline is being made at the present time. During the past six years the Bureau of Mines has made semi-annual surveys of the gasoline marketed in the United States, the survey just completed being the thirteenth in the series. The cities in which samples have been collected have been chosen as representative of the more important marketing territories as it is obviously impracticable to obtain a sample of every gasoline sold in the entire country.

Jan 1, 1926