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By R. W. Watson

This Bureau of Mines report summarizes some recent results on the sensitivity of various experimental explosive systems using ammonium nitrate (AN) as the oxidizing agent. The sensitivity survey included drop-weight and friction testing and sensitivity to initiation by projectile impact and a No.8 blasting cap. It was found that certain types of AN prills can result in cap-sensitive mixtures when combined with No.2 diesel fuel (Fa); prilled AN mixed with nitromethane also result in cap-sensitive mixtures. Mixtures of AN prills and neat 1-and 2-nitropropane were not cap-sensitive, and the use of powdered or grained aluminum in AN-FO did not adversely affect the sensitivity except possibly to increase its sensitivity to friction.

Jan 1, 1974

Determine the dust reduction capabilities of various bag valves available to the minerals processing industry. The Problem Many different types of ground mineral products are packaged into 50-and 100-lb paper bags. Although bag technology is continually improving, dust contamination from bags still remains a significant problem for workers. The greatest source of dust is the bag filling valve. Ideally, the bag filling valve should close after it fills the bag with the ground mineral product. However, the valve usually fails to close properly since some mineral product gets trapped inside the valve during filling and ejection. As a result, when the bag has been filled and falls from the fill station, a rooster-tail of product is discharged from the bag valve. As the bag hits the conveyor belt, additional product discharges from the bag valve. The dust from these sources contaminates the air inspired by the workers filling the bags as well as the work area. Dust also clings to the outside of the bag, contaminating the pallet loading station. Because the various commercial bag valves are composed of different materials, a dust analysis was performed on five of these valves to determine their dust reduction capabilities. The five valves analyzed were: standard paper, polyethylene, extended polyethylene, double trap, and foam.

Jan 1, 1986

Improve underground mine roof bolt support systems by alleviating problems associated with certain ground support systems currently being used. Approach Convert a passive resin-grouted roof bolt system into a uniform, tensionable roof bolting system. Background Resin-grouted roof bolts are one of the most common forms of ground support in U.S. underground coal mines. These support systems can be installed with a full-column of grout and be loaded with subsequent roof movements after installation. This is called a "passive" support system. An alternative to the passive support system is the mechanically-anchored, tensioned roof bolt system. This system is installed with resin grout. This system is designed to load or tension the support during installation by using a mechanical anchor, coupling, or threaded nut after the resin has properly cured. It is called an "active" support system and is used extensively for improved strata control in a laminated geologic deposition or in difficult ground conditions. To ensure that active bolts have been properly installed, the bolt loads must be checked by using a torque wrench or other suitable equipment. Unfortunately, this practice presents potential safety hazards and has limited accuracy. Laboratory and field experiments also reveal that the torque-to-tension ratio developed on active support systems can vary by 50% from bolt-to-bolt. Variations in bolt load installations can induce stress concentrations and lead to roof degradation or failure.

Jan 1, 1991

By Rustu S. Kalyoncu

Nonoxide ceramics with improved high-temperature properties could substitute for high-temperature alloys and reduce toe Nation's dependence on imports of Cr, Co, Ni, and Mn. To meet this objective, the Bureau of Mines conducted research to synthesize u1trafine reactive boron nitride (BN) powders BN powders were prepared at temperatures ranging from -75? to 750? C. Low-temperature reactions (-75? to 200? C) between boron halides and N compounds led to formation of e1emento-organic compounds that were thermally decomposed to u1trafine (approximately 100-to 150-A particle size) reactive BN powders. BN powders were also prepared through the reaction of a 10w-me1tinginorganic B compound (boric acid, borax) with an organic N compound (carbimide and thiocarbimide) in N2 and/or ammonia (NH3) atmospheres at temperatures between 500? and 750? C.

Jan 1, 1986

By Charles M. McCulloch

This Bureau of Mines report discusses the principles of using computers to draw maps and plot geologic data of mining areas. The types of maps that can be drawn by a computer are reviewed, using as examples two separate areas where poor roof and gas emissions caused mining problems. Such maps can be used not only to help identify problem areas, but also to predict areas where problems could occur, thus giving mine operators time to work out solutions prior to mining. The average cost of a computer-drawn map for a mine property is less than $100, including computer time and man-hours for data preparation.

Jan 1, 1976

To improve safety by making speed and direction control of a tracked vehicle simpler and instinctive. Approach A joystick control (which determines vehicle speed and direction of movement as well as the direction of any turning or pivoting) was developed and tested on a loading machine during a long-term underground demonstration. How It Works The control box actuated by the joystick lever contains two multiposition, multideck rotary switches. Fore-aft movement of the joystick rotates one switch through five positions to provide a neutral position and two speeds of travel in both

Jan 1, 1978

By D. K. Dysinger

In this U.S. Bureau of Mines study, neodymium metal of 99.8 pct purity was prepared by electrolysis of Nd203 salts dissolved in a molten fluoride electrolyte. The metal was electrowon in a molten state at current efficiencies of 50 to 60 pct. Oxygen and carbon were the major impurities detected in the product. During operation of the small-scale laboratory cell, a number of technical problems including anode effect, low oxide solubility in the electrolyte, high neodymium metal solubility, reactivity of the metal with the cell materials, and back reaction of the metal with the anode gases were encountered. Approaches to improve cell operation and prospects for commercial adoption of the electrolytic production of neodymium metal are discussed.

Jan 1, 2010

By J. Croeni

The search for new alloys for application in the atomic energy field had prompted investigation of zirconium-rare earth metal alloys by the Federal Bureau of Mines. In this instance the zirconium-dysprosium system was investigated by melting point, thermal analysis, resistivity, X-ray and metallographic methods. Results indicate a single eutectic system with a peritectoid reaction occurring at 890° C. The eutectic isotherm extends from 30 to 95-percent dysprosium at 1,280° C. Eutectic composition is located at approximately 70 percent dysprosium. Solid solubility of dysprosium in both alpha and beta zirconium is extensive. The extent of solid solubility of zirconium in dysprosium has not been determined. Although zirconium rich alloys exhibit a significant increase in hardness, they can be cold worked extensively. These alloys also appear adaptable to solution heat treatment. Additional investigations concerning corrosion resistance and other mechanical properties are necessary for satisfactory evaluation of these alloys. The superior corrosion resistance of zirconium and the nuclear cross-section characteristics of the rare earth metals have stimulated alloy investigations using zirconium as a base metal. Alloys combining these characteristics present a possible substitute for hafnium as a control rod material. In this particular study dysprosium was chosen as the alloying element, and several series of alloys were used to establish the equilibrium diagram.

Jan 1, 1960

Limestone formations in the United States can be subject to relatively high horizontal stresses due to the existence of tectonic loading of the limestone strata. Underground limestone mines use the room-and-pillar method, in which 12- to 18-m-wide rooms are typically excavated. The stability of these excavations can be compromised by the horizontal stress, resulting in a rockfall hazard. Rockfalls are the cause of 15% of all reportable injuries in underground limestone mines. Horizontal stress related damage can occur in the form of guttering along one or more sides of an excavation, roof beam buckling or oval shaped roof falls, with the long axis perpendicular to the major horizontal stress. Numerical analyses show that the pillar layout and orientation of the mine workings have an effect on the horizontal stress distribution within the roof. The effects of high horizontal stresses can be mitigated by orientating the heading development direction parallel to the maximum horizontal stress, reducing the number of cross-cuts and offsetting the cross-cuts to limit the potential lateral extent of horizontal stress related roof falls. The modeling approach described in this paper can be used as a tool to evaluate potential roof failure and optimize the stability of room and pillar layouts.

Jan 1, 2008

By G. L. Gates

The Bureau of Mines studied the scales formed in producing wells in the Wilmington field, California. The scales were primarily barium sulfate and resulted from the mixing of injected sea water and formation waters; there was excess sulfate in the injection water and the formation waters contained appreciable barium. After breakthrough, the produced brines were supersaturated with barium sulfate. Laboratory tests indicated that barium sulfate precipitated quickly When the supersaturated brines were agitated with crystals of barium sulfate and fairly rapidly when more sulfate solution was added. Precipitation occurred slowly on standing or under nonturbulent conditions. Both the apparent and equilibrium solubilities of barium sulfate in these brines were determined and compared with equilibrium solubilities in distilled water and sodium chloride solutions.

Jan 1, 1965

By James S. Browning

The Bureau of Mines conducted laboratory batch and pilot plant flotation tests to determine the technical feasibility of recovering commercial-grade mica from a California micaceous schist. Best results in the laboratory batch tests were obtained using sodium carbonate and sodium silicate for pH control and quartz depression, and a combination of fatty acid and cationic reagents as the mica collector. In continuous pilot plant flotation tests, an alkaline fatty acid-cationic method recovered about 70 percent of the mica in a concentrate analyzing 95.6 percent mica.

Jan 1, 1965

By F. E. Brantley, D. A. Martin

Synthetic zeolites were tried as selective adsorbents for recovering sulfur dioxide from synthetic gases and gases produced from gypsum decomposition . Initial adsorption tests , using the synthetic gases , indicated that three of these compounds , having sulfur dioxide capacities of up to 29 grams per 100 grams of adsorbent , were satisfactory . Regeneration studies showed that over 90 pct of the sulfur dioxide desorbed from the loaded beds was of sufficient purity for direct liquefaction . However , all zeolites tested lost adsorptive capacity with repeated use . The zeolite determined to be the most promising in the preliminary synthetic gas tests was also evaluated for capability in adsorbing sulfur dioxide from gases produced by the thermal decomposition of gypsum . Despite small amounts of hydrogen sulfide in the gypsum decomposition offgas , good adsorption of sulfur dioxide was attained . The economic practicality of utilizing zeolites for sulfur dioxide removal from industrial gases was not evaluated , but the technical feasibility was demonstrated .

Jan 1, 1963

By J. R. Hauger, P. A. Romans, W. J. Niebuhr

With suitable instrumentation and techniques it is possible to determine the presence of tantalum in columbium to 20 ppm . This paper discusses the selection of X- ray spectrographic instrumentation and describes a technique for accomplishing the low level determination of tantalum . An ion- exchange method of separating tantalum from columbium is also described .

Jan 1, 1964

Recent Bureau of Mines research in earth grounding safety is documented in three separate papers. First, guidelines for the design of a 5- ohm borehole ground are presented. Next, an inexpensive practical means to construct a low-resistance bed in high-resistivity soil is described. Finally, a procedure that employs a commercial resistivity meter to measure shock potentials around grounded objects is explained step-by-step. These papers complement the material presented at an earlier technology transfer seminar and published as IC 8767.

Jan 1, 1985

By Richard F. Hewlett

An attempt has been made to fit assay data from an underground copper deposit to a three-dimensional polynomial surface as a means of expressing assay points in terms of their mine coordinates by a mathematical equation. The resulting equation was evaluated to predict the grade trend of the deposit. Although the fit obtained by this initial experiment is not considered accurate enough to provide good predictions about the deposit, the methodology is presented in this preliminary report to show the potential usefulness of the technique in mineral deposit evaluation. The technique also should be useful in determining the grade of blocks of ore for production scheduling and blending problems in open pit operations. Further experimentation is needed to increase the reliability of the computer program, to increase the precision of the method, and to make the solution more flexible for use on other mineral deposits.

Jan 1, 1964

By R. L. Grayson, W. E. Wallace, T. Simonyi, J. C. Harrison

"Application of an SEM-based methodology suggests a reason for past contradictory results on the relationship between quartz and coal workers' pneumoconiosis (CWP). Results indicate that coal seams with the same bulk analysis of quartz may have different amounts of surface-availablequartz. Our research shows that the amounts of pure and surface-available quartz in a respirable dust vary directly with the rank of a coal seam, except in the case where rock materials are mined. The estimated amount of surface-available quartz therefore provides a measure of the quartz-related fibrogenic potential of a respirable dust.INTRODUCTIONFrom our previous work (Grayson, 1991), we have shown that the amount of pure quartz in a respirable coal mine dust sample appears to vary directly with the rank of the seam (using fixed carbon as the basis for comparison), except when a substantial rock parting, roof or floor are mined. Our other work (Wallace et al., 1989) showed that high-silica particles in a clay mine may generally be coated with clay, rendering the quartz core non-available for surface reaction in the lung. The combination of these findings led us to hypothesize that the coating phenomenon may indeed be present in coal mines as well, and that a rank relationship may be present regarding this phenomenon. Thus higher rank coal seams may have more surface-available quartz as well as more pure quartz particles in their respirable dusts. The scientific protocol for testing this hypothesis and the results obtained to date are discussed in this paper. Thus far, there is no reason to doubt that the relationship holds."

Mar 1, 1992

Develop a curved ray geotomographic program with constraints to counteract non-uniqueness in order to improve the reliability of seismic tomographic imaging of geological structure in mining regions. Background Seismic tomography provides a two-dimensional image (tomographic reconstruction) of the distribution of the seismic velocity in geologic structures using measured travel times of seismic waves crossing the area. It can provide a more complete representation of features be¬tween boreholes than other crosshole processing methods that measure only average properties or borehole logging methods that measure properties only near each borehole. Seismic tomography has many mining applications. They include locating geologic structures of contrasting seismic velocity, detecting fractured regions where the seismic velocity is low, and monitoring solution injected above the water table where the increase in saturation increases the seismic velocity. Thus, tomographic imaging techniques show great promise for detecting and locating geologic hazards that affect the productivity, safety, and environment of mining operations.

Jan 1, 1992

By David D. Walker

The purpose of the investigation was to describe and appraise tungsten deposits in Montana . The work supplements previous investigations made by Pattee ( 10 ) and Walker ( 17 ) in selected areas of the State . Scheelite deposits in tactite are the most numerous and most important economically , having accounted for nearly all of the State's tungsten production . Of the 64 deposits examined during the current study , 50 contained scheelite , 11 hubnerite , 2 wolframite , and 1 ferberite . The State's major tungsten production has been from scheelite deposits in Beaverhead County . The report lists , by counties , the type and grade of each deposit . The more important occurrences are accompanied by geological and assay maps .

Jan 1, 1963

By D. W. Butner

The blast -hole method for drilling and breaking ground is not new to the mining industry . For several years it has been used rather extensively in Canada , particularly in the gold mines , where it was first developed and where the major advances in the technique as applied to present - day mining problems have been made . At present , 40 mines in Canada and the United States are using the method in one form or another , and from all indications its use will increase in the future . In two California mines , blast -hole diamond drilling is now used for a part of or for all stoping operations , and in one of these it is used to some extent in development work . At the Mountain Copper Co.'s Hornet mine in Shasta County, about 50 percent of the pyritic sulfide ore produced is mined by the blast - hole method , and the U. S. Vanadium Corp. mines 80 percent of the ore produced at its Pine Creek tungsten mine in Inyo County by this method . At Pine Creek , long -hole drilling and blasting is used for mining pillars also , and in pre - stoping development . The blast -hole diamond - drilling method is not applicable to all types of ore bodies . A third property in California , the El Dorado Limestone Company , El Dorado County, tried the method for several months in 1943 and 1944 , but , owing to certain factors that greatly increased mining cost , the company soon returned to conventional mining methods .

Feb 1, 1948

By W. G. Bradley

THIS PAPER describing the quarrying, mining, and crushing of gypsum at the Blue Diamond mine, 11 miles from Arden, Nev., on the Union Pacific Railway, is one of a series on gypsum mining being prepared for and published by the Bureau of Mines. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent operating expenditures only and not total costs. It is recognized that publication of total production costs might in some instances cause embarrassment to individual producers as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue.

Jan 1, 1932