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By J. W. Walkiewicz

The Bureau of Mines investigated alloys containing mischmetal (MM), cobalt, copper, magnesium, and iron for use in permanent magnets in place of the scarce samarium-cobalt alloys. The magnetic properties of MM-Co, MM-Co-Cu, MM-Co-Cu-Mg, and MM-Co-Cu-Fe-Mg alloys were evaluated. Magnets were fabricated by powder metallurgy consisting of arc-melting the metals, crushing and grinding the resultant alloys, alining and compacting the powder, and sintering the compacts. Magnetic values of MHc = 4.7 kOe, BHc = 4.07 kOe, Br = 6.81 kG, and (BH)max = 10.0 MGOe were obtained with a MM-Co alloy containing 36±0.5 wt-pct MM. By substituting copper and magnesium for part of the cobalt, the values for MHc and BHc were increased to 29.0 kOe and 5.89 kOe, respectively. This intrinsic coercivity value exceeded that of Sm-Co alloy obtained in our laboratory. The addition of iron to MM-Co-Cu-Mg alloys resulted in an increase of Br to 6.90 kG and (BH)max to 10.3 MGOe. Copper and magnesium contents of these alloys were optimized to obtain maximum values of MHc.

Jan 1, 1981

By D. W. Frommer

Processing of nonmagnetic taconites by selective flocculation-des liming and anionic flotation of calcium-activated silica has been investigated using innovative procedures as a means of improving operating costs. Areas chosen for cost-cutting evaluation were grinding, fine screening, and water conservation and reclamation. The investigation was performed on Marquette range nonmagnetic taconites in the Bureau of Mines Twin Cities Metallurgy Research Center flotation pilot plant, at feed rates ranging between 900 and 1,100 lb/hr. With fully integrated water reclamation, flotation concentrates containing 65.8 percent Fe and 3.4 percent Si02 were made in the best operating period, with accompanying weight and iron recoveries of 40 and 74 percent, respectively. During this same period, the estimated cost of both flotation and water reclamation reagents was only $0.80 per ton of concentrate (1968 pricing basis). This cost is about 15 percent lower than obtained previously at this Center for flotation reagents only. The investigation demonstrated additional potential savings in operating costs of approximately $0.96 per ton of concentrate through autogenous grinding as a substitute for ballmilling. Fine screening of intermediate concentrates was employed advantageously, but the frequency of blinding may be a factor militating against use of the screen in this flotation system.

Jan 1, 1973

By Andrew J. Fergus

A study of the flotation characteristics of columbium-tantalum minerals was made by contact-angle and microflotation methods, and the findings were confirmed by flotation of two natural ores. In the contact-angle study conditions for collection of columbite, pyrochlore, and tantalite were determined for (1) sodium oleate with a sulfonate; (2) sodium isooctyl phosphate; (3) a short-chain primary amine; (4) a long-chain primary amine; and (5) a quaternary amine. These conditions were confirmed in microflotation tests. Information about collector action on common gangue minerals was also obtained by these two methods. In batch flotation tests on a pyrochlore ore and a columbite ore, it was demonstrated that collectors selected on the basis of contact-angle and micro-flotation studies would float columbium minerals from a complex natural ore. However, multiple cleaner and scavenger flotation steps will be necessary to produce commercial concentrates. From a pyrochlore ore containing 0.54 percent Cb2O5, a 44.4 percent Cb2O5 concentrate was made containing 36.4 percent of the total Cb2O5. For a columbite are the corresponding values were: 4.35, 54.6, and 67.1 percent. During the batch flotation study, wetting agents were found to aid in the gangue-ore mineral separations.

Jan 1, 1968

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

A. 4 Illustrative Simulations The capabilities of the program are demonstrated by simulating various evacuation cases in different situations for a particular mine. The mine selected for the illustrative simulations is the mine I C' , as described in Section 2, chosen particularly because of availability of mine characteristic data and mine evacuation results for test drills. These evacuation results can be used to verify validity of the predictions made by the program A.4 1 Mine Characteristics A schematic diagram of the mine is shown in Figure 19. The figure shows all the major shafts, drifts, raises and stopes of the mine in the form of a network. There are four hoists, Hoist No. 1 and Hoist No. 2 are assumed to be single drum hoists and Hoists Nos. 3 and 4 form part of a double drum hoist, with Hoist No. 4 being the main hoist (master hoist) The positions of the 133 miners, typically working in a day shift of the mine, are also shown in the figure. The miners are identified by a miner number, and their total number on each level is chosen from the data on the fire drill simulated as Case No. 1 in the illustrative simulations.

Jan 1, 1976

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

7. Development of Acoustic Seal Checking System The acoustic approach was shown in Section 4 of this report to be the most promising concept for checking the seals. This section describes the development of this concept into a working hardware system to be used later in the field test program. This development effort included: (1) Theoretical analysis of the acoustic behavior in the mine using acoustic modeling- techniques. (2) Experimental determination of acoustic patterns in mine passages. (3) Refinement of the theoretical model. (4) Verification of final theoretical predictions in the quarter-scale laboratory model of a mine passage and seal. (5) Development of system specifications. (6) Development of the Acoustic Prototype Seal Checking System. 7. 1 Analysis of the Acoustic Seal Checker Concept The acoustic seal checker concept is based on a model which combines corridor acoustics and hole transmission theory. The idealized model for the mine sealing application is shown schematically in Figure 66. A high intensity acoustic- source is located in a corridor at a, position adjacent to the location to be sealed. The acoustic signal transmitted through the seal is monitored by a microphone pick-up placed on the opposite side.

Jan 1, 1973

By Alan R. Buehler

The Bureau of Mines conducted a mineral investigation of the 32,270-hectare Cache Peak study area in 1992; the area had been proposed as wilderness. Bureau personnel examined and sampled prospect workings; 50 rock and placer samples were taken during the investigation. The study area is centered about 25 km southeast of Challis, Idaho, in the Challis National Forest. According to May, 1993, Bureau of Land Management mining claim records there were no current mining claims located inside the study area. Up to 100 claims may have been located in the study area in the past. Gold, silver, copper, lead, zinc: Significant analyses, poor exposure precludes resource estimate. Limestone: More than I billion tonnes may be chemically suitable for a variety of uses, markets too distant to favor mining. Dolomite: More than 1 billion tonnes may be chemically suitable for producing magnesium metal, markets too distant to favor mining. Sand and Gravel: Several million m3, but markets and transportation costs do not favor mining. Chalcedonic nodules: Two localities in the study area may be of interest to hobbyists who cut and polish stone. There is no reported past production from the study area.

Jan 1, 1993

By H. S. Caldwell

This report describes work by the Bureau of Mines on the vacuum distilla¬tion of some of the more volatile metals such as cadmium, zinc, and magnesium from lead and tin. Evacuation within a distillation apparatus allows rapid diffusion of vapor away from the evaporation surface and prevents reaction of the vapor with residual gases. A reduction of pressure to several tenths of a millimeter makes possible practicable distillation rates, at temperatures for which the partial pressure of the metal vapor exceeds 10-3 atmosphere. The rate and selectivity of distillation depend primarily on the volatility and molal ratios of the alloy metals, and their chemical activity to each other. For very rapid evaporation or low concentration of the more volatile constituent, the rate is determined by the rate of diffusion of the evaporating metal, to the surface of the melt. Cadmium, zinc, magnesium, and tellurium were found to volatilize readily from both lead and tin. Tellurium appears to volatilize as an intermetallic compound rather than the pure metal. Antimony could not be removed from lead at 1,000° C.; the condensate was nearly all lead. Antimony, bismuth, and lead were removed from tin.

Jan 1, 1960

Reduce the number of conveyor-related accidents in the mining industry by providing recommendations for effective operation of conveyor belt cleaning systems. The Problem Troughed belt conveyors provide effective, and efficient materials transport and their use has increased throughout the mining industry. Carryback, the spillage that accumulates under the belt, is a problem even with belt cleaning systems installed. Mining personnel are exposed to safety and health hazard; as they attempt to clean up this spillage. Approach To investigate the influence of metal-segmented-blade belt cleaners on the amount of carryback spillage, the. Bureau identified and tested the following parameters: (1) amount of pressure applied to the cleaner blades, (2) friction between the blades and conveyor belt, and (3) wear rates of different metal blades. The test parameters were quantified by recording the amount of carryback material passing the metal cleaner blade, and the weight loss of the blades. The data collected were used to identify the following critic d operational parameters of a segmented-blade conveyor cleaner system: (1) the existence of an optimal operating pressure for the conveyor and cleaning systems and (2) elimination of recessed patterns on the working side of the conveyor belt.

Jan 1, 1989

Promote safer and more efficient mine operations by providing communications between personnel located anywhere in the mine. Approach A radio communications system was designed which takes advantage of existing mine wiring such as telephone lines or electric power cables. The existing wiring distributes radio signals throughout the mine, making communications possible between roving miners, vehicle operators, dispatchers, and other personnel. How It Works Research has shown that medium frequency (MF) signals (300 KHZ-3 MHZ) can couple onto and re-radiate from nearby conductors. This effect is known as parasitic coupling and re-radiation. In a mine, these conductors include electric power cables, control lines, telephone lines, trolley lines, as well as metal water and air pipes Since all underground mines require these conductors for normal operations, the necessary network already exists and expands automatically as the mine is developed. A radio communication system has been developed that uses the parasitic coupling and re-radiation characteristic of MF. Using this system, whole mine radio coverage can be achieved without the need to install or maintain communication lines. The system consists of mobile transceivers for roving personnel and vehicles, and fixed-location base radio stations and repeaters.

Jan 1, 1982

By R. V. Ramani, C. B. Manula, A. Owili-Eger

MINE PROTOTYPE The prototype chosen for application demonstration is from Kingery (1960). The mine and the ventilation plan is presented in Figure 11. A new coal mine is projected with entrance by slope 1,500 feet long. Nine train entries will be standard for development, five as intake and four as return. One return shaft is planned near the slope bottom. The slope will have an area of 150 square feet and a perimeter of 55 feet. The return shaft will be circular with a diameter of 18 feet and will be 500 feet deep. Two hundred feet of the shaft and 500 feet of the slope will be concrete lined. Will it be possible to operate five units per shift with amount of air at each unit not less than 25,000 cfm? Additionally, a shop at the slope bottom will require 10,000 cfm. The problem is completely worked out using standard ventilation formulas and simple manual calculations in the above reference and is reproduced here in Appendix II for ready reference. APPLICATION In this manual, four different applications of the PSU/MVS are outlined. An article by Stefanko et al (1972), outlines how one can move from a mine map to a network for the generation of computer input. Attention is drawn to Figure 12, which is the network line diagram of the mine ventilation system in Figure 11. Note that every roadway junction has been numbered. The dotted lines represent leakage paths and the letter 'R' on a branch denotes that the split is regulated for the quantity shown. For example, there is a leakage

Jan 1, 1975

By Terry S. Cory

This report covers magnetic field strength measurements vs range and frequency in low-medium coal mines. Both quasi-conductor-free and conductor-proximity areas were investigated. The program covered 5 mines, 4 seams, 6 measurement sets, and 3 geographic areas. The results have been summarized in terms of maximum communication range expected per seam and noise condition. Scatter gain is further explored as a simple measure of energy coupled to conductors.

Jan 6, 1978

By M. E. Poad, M. M. McDonald, J. C. Johnson, W. G. Pariseau

A U.S. Bureau of Mines case study of pillar recovery in high-grade ore near the Ross shaft at the Homestake Mine, Lead, SD, has demonstrated the usefulness of the finite-element method for evaluating shaft pillar mining plans and shaft stability. In this study, borehole extensometers and other instruments were installed to provide data for model verification and to monitor shaft displacement. Results of a recalibrated two-dimensional model (UTAH2)confirmed the premining stability evaluation. However, after mining began, concern developed because of cracks and other signs of ground motion that appeared at considerable distances from the area of active pillar mining. An intense three-dimensional modeling effort using the computer modeling program UTAH3 was initiated. The results again showed the observed effects were within expectations and that the shaft would remain safe. Three-dimensional analyses of alternate pillar mining scenarios indicated that more of the shaft pillar ore reserve could be recovered than previously thought on the basis of two-dimensional analyses. This report focuses on startup and implementation of the three-dimensional model, calibration of the three-dimensional model, and application of the model to shaft pillar mining.

Jan 1, 1996

By J. A. Organiscak

The U.S. Bureau of Mines recently conducted an investigation into the amount of respirable and quartz dust generated while mining rock in coal mines by continuous and conventional methods. The study was made at two mines that use both continuous and conventional mining. Results show that continuous mining produces 1.2 to 3 times more respirable dust, and 6.7 to nearly 15 times more quartz dust than conventional mining.

Jan 1, 1989

In 2001, a total of 2,144 coal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Coal mines comprised 14.7% of all mining operations. • Bituminous mines comprised 92.0% (n=1,972) and anthracite mines 8.0% (n=172) of coal mining operations. • More than 71% of coal mines were located in three states: Kentucky (29.5%), West Virginia (21.3%), and Pennsylvania (20.6%).

Apr 1, 2003

By Peter J. Clarke

Afghanistan's mineral industry continued to be dominated by the production and export of natural gas, although several mining and related industrial projects, all under the supervision of Soviet technicians, were in the planning stage in 1982. Afghanistan produced minor quantities of barite, cement, coal, fertilizer materials, iron, and lapis lazuli, all for domestic consumption.2 Large-scale projects being investigated were a copper mine and concentrating plant at Ainak, extensive mining of the Hajigak iron ore deposit near Kabul, construction of an oil refinery at Angot, increasing production and processing of natural gas, and implementing an intensive geologic prospecting and exploration program for areas of mineral potential. Afghanistan's gross domestic product (GDP) was estimated at $2.76 billion3 and has remained stagnant for the past several years. Total exports in 1982 were estimated at $700 million, only a marginal increase from the 1981 figure of $694 million. Exports of natural gas to the U.S.S.R. earned $385 million in 1982, representing just over one-half of Afghanistan's total exports. Natural gas revenues were down approximately 11% from the 1981 level, owing primarily to increased antigovernment activity in the northern part of the country.4 About 90% of the country's natural gas production was exported to the U.S.S.R.5 About 38% of Afghanistan's development budget had been earmarked for mining and industrial projects in 1982.6

Jan 1, 1984

By Harold L. Rhodes

Vapor-liquid equilibria data for 65-34-1 and 25-27-48 mole percent helium-nitrogen-methane mixtures are presented for 12 temperatures from 76.5° to 164° K and pressures from 100 to 1,200 psia. These data were obtained in a windowed phase equilibria cell equipped with a vapor recirculating pump. Isobaric and isothermal K-values are plotted for both mixtures. Two isometric plots are included.

Jan 1, 1972

Underground and strip mining (6,7) produce different hydrologic environments. Many underground mines are below the zone that is completely saturated with water and the mine openings may cause new and continuous contact between sulfurous material and water which flows from the saturated zone to the workings. Strip mines are usually above the zone of continuous saturation and contact between sulfurous material and water is generally restricted to periods of precipitation. A full appreciation of the problem of water pollution caused by drainage from deep mines requires a basic understanding of occurrences and movement of water in the ground and the modes of ground water entrance into mining areas.

Jan 1, 1970

By R. L. Montgomery

Heats of solution of cerium metal and cerium (III) chloride in hydrochloric acid were measured. The standard heat of formation of the aqueous cerium (III) ion at 25° C is -166.1 ± 0.3 kcal/mole. Heats of solution of cerium (III) chloride in hydrochloric acid are consistent with the existence of a complex CeC1++ having a stability constant of 1 and a heat of complexing of 5.4 kcal/mole.

Jan 1, 1962

By William J. Wiehagen

This is the third in a series of four articles that discuss underground fire-fighting preparedness. As with the first two articles, it is based on interviews with 214 miners conducted at 7 underground coal mines (referred to as Mines ?A? through ?G?) by researchers of the National Institute for Occupational Safety and Health?s (NIOSH) Pittsburgh Research Center [Vaught et al. 1996]. In the first article, the authors presented an overview of the study conducted by NIOSH on mine fire response preparedness and provided a general perspective on underground mine fires. The second article discussed miners? preparedness to evacuate a fire and their experience with incipient fires. In this article, we describe miners? experience in fighting underground mine fires and present their perceptions of training and readiness for fire-fighting.

Jan 1, 1997

By Maria I. De Rosa

This report analyzes mobile equipment fires for all U.S. surface and underground coal and metal/nonmetal mining categories by state and 2 year time periods during 1990-1999. Risk rate values are derived, and ignition source, methods of fire detection and suppression, and other variables are examined. The data were derived from MSHA mine fire accident publications and verbal communications with mine personnel. The analyses will provide the National Institute for Occupational Safety and Health (NIOSH), the Mine Safety and Health Administration (MSHA), and the mining industry with a better understanding of the hazards associated with mobile equipment fires and will create a basis for future fire research programs.

Jan 1, 2004