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By Donald O. Capstick

A mineral survey of a 13,525-acre portion of the 21,875-acre Owyhee Canyon Wilderness Study Area in northern Nevada was conducted by the U.S. Bureau of Mines in 1984. Two samples from sand and gravel deposits in the study area contained minor placer gold typical of the Owyhee River area. The gold-bearing gravels are too low grade or of insufficient volume to support commercial placer mining operations. The sand and gravel deposits might have minor local construction uses.

Jan 1, 1986

By George S. Koch

The distribution of gold in part of the Getchell mine, Humboldt County, Nev., is presented through the statistical analysis of 956 assays of rock cuttings from wagon-drill holes. Two methods to predict grade in undeveloped parts of the ore body are evaluated, and the possibility of sampling bias is tested. The distribution of gold is compared with that in three other Nevada gold deposits of the same type characterized by gold particles mostly of submicron size associated with carbonaceous rocks, and also with that in deposits with coarse-grained gold. Usually, fewer samples of a given type are required to make a satisfactory grade estimate for submicron deposits than for coarse-grained deposits. The economic consequence is that submicron gold deposits are likely to be less expensive to sample and evaluate than coarse-grained deposits.

Jan 1, 1970

By Kevin Michael, David C. Byrne

In previous issue of Spectrum (October 1999, 16/4), a system of measuring the attenuation provided by insert-type hearing protectors was described, That report described experiences using the FitCheck (Michael & Associates, Inc.) system in a pilot project involving the steel industry during 1998.[ ]

By N. A. Gokcen

Equilibrium partial pressures of gaseous HCl and H2O over aqueous binary and ternary solutions of HCl and AICls were calculated or estimated in the range of 20° to 110° C, and up to saturation with AlC13?6H2O. The results were extended to solutions containing less than 10 wt-pct FeCl3 by assuming that FeCl3 and AIC13 are equivalent on the molar basis, since both salts have trivalent cations with a cammon anion. The ionic activity coefficient of HCl and the equilibrium constant for dissolution of gaseous HCl were also computed. This research is part of the effort by the Bureau of Mines, U.S. Department of the Interior, to provide thermodynamic data to expand the technology base relevant to the extraction of alumina from nonbauxitic domestic raw materials.

Jan 1, 1980

By R. L. Montgomery

The heats of solution of erbium chloride in water and in hydrochloric acid and of erbium oxide in hydrochloric acid were determined. The results reveal a discrepancy of 10.5 kcal. per gram-atom between the heats of combustion and solution of erbium reported in the literature, the heat of combustion being more negative. The heat of combustion of erbium t4)4 and its heat of solution in hydrochloric acid (1, 18) have been reported in the literature. The heat of solution of erbium chloride was determined in two studies (2, 19). The present work was undertaken to check the reported heats of solution of erbium chloride and to determine the heat of solution of erbium oxide in hydrochloric acid. The latter quantity permits the heats of combustion and solution of erbium to be compared for mutual consistency. It was also desired to determine the degree of similarity between the thermochemistry of yttrium and erbium.

Jan 1, 1961

By Paul T. Allsman

THE THREE words, research, mechanization, and automation are keynote words for mining technology during 1962. Basically interrelated, they not only express the major technologic developments in mining but are the signposts pointing out the road ahead. The process represented by each of these words is evolutionary rather than revolutionary, but developments during the past year indicate a climactical stage has been reached in the process of evolution. Mining research has progressed beyond the stage of academic discussion and is a programed activity within the Federal Government,3 the mining colleges,4 and many of the large mining companies.5 Research was a major agenda item at various national and international mining meetings in 1962. A list of these meetings would include such diverse locales as the Workshop and Symposium on Computers and Computer Applications in Mining and Exploration at the University of Arizona in March; and the 5th Rock Mechanics Symposium at the University of Minnesota, in May; the Rock Mechanics Symposium at McGill University, Montreal, Canada, in September; and the Colloquium XIII, International Society for Rock Mechanics, at Salzburg, Austria, in November.

Jan 1, 1963

By Ernesto Villaescusa, Andres Brzovic

Rock masses of the primary copper ore at the El Teniente Mine are very competent and massive. The rock mass contains almost no open discontinuities. Nevertheless, there is a high frequency network of small discontinuities coupled with widely spaced faults. A data collection campaign designed to characterize the rock structure was recently implemented. The results show that conventional analysis in terms of discontinuity frequency does not predict differences between two studied sectors. However, when an empirical definition of a weak discontinuity is applied, appreciable differences between the two sectors appear in terms of discontinuity frequency and predicted in situ block size distributions. These differences are in accordance with actual observations at the mine site. Due to the geological features of the primary copper ore, rock mass classification schemes cannot be readily applied to characterize these rock masses.

Jan 5, 2007

Develop a reliable, portable device for non-destructively testing the support integrity of a friction rock support (commonly referred to as a Split Set ). Approach The friction rock support, used to support mine roof and ribs, is a slotted tube driven into a drilled hole of smaller diameter. Upon installation, the tube is compressed radially. The amount of compression is a function of the hole diameter, the strength of the host rock, and the properties of the split set itself. A simple lightweight self-contained device was developed to determine the pull-out resistance of the friction rock supports in-situ, based on measurements of the tube's deformation. The tester measures the com-pressed internal volume of the slotted tube, which has been found to provide an estimate of the support's resistance to pull out. How It Works The tester consists of a pump and expander sections. The expander sections are made from an elastomer membrane which is stretched over two cores, each one inch in diameter and twelve inches long. The expanders are connected by a flexible coupler so that they can fit any alignment of the support.

Jan 1, 1984

Develop rugged, cost-effective fire protection for hydraulic shovels and backhoes. Approach Automatic fire sensing and suppression systems were designed and built for use on hydraulic shovels and backhoes. How It Works A line-type temperature sensor is mounted in the machine's engine and hydraulic pump areas to detect the heat from a fire while it is still small and easy to control. Two systems were tested. In one, the inside of the sensor consists of two conductors separated by a ceramic material whose electrical resistance decreases with increases in temperature. When heated to a predetermined temperature) the control circuit responds to the resistance drop. In the second system, the detection element of the sensor is comprised of a thin metal tube containing a hydrogen charged metal hydride wire. The tube is sealed at one end and is connected to a sensitive pressure switch at the other end. When exposed to the heat from a fire, hydrogen gas released from the metal hydride wire actuates the pressure switch.

Jan 1, 1980

By D. E. Hirsch

The Bureau of Mines has developed a systematic procedure for separation, characterization, and semiquantitative analysis of high-boiling (350° to 550° C) distillates of crude oils. Isothermal and molecular distillation were used to prepare the 370° to 530° C distillate of Recluse, Wyo., crude oil. The distillate was separated into fractions by chemical treatment, silica-alumina gel adsorption, and gel permeation chromatography (GPC). The fractions were analyzed by use of GPC correlations and mass and nuclear magnetic resonance (NMR) spectrometry. The increased knowledge of petroleum composition obtained from the data will contribute to improved petroleum processing and utilization and energy conservation.

Jan 1, 1974

By Joseph A. Sutton

The prospect of utilizing bacteria in mining and metallurgical processes introduces a new and challenging area of investigation. Elements of bacteriology and metallurgy are discussed in connection with possible areas where biological science might be applied in extractive metallurgy. Bacteria may prove important in the selective separation of metals from ores and metallurgical solutions, the production of sulfur from gypsum or pyrites, and the production of sulfuric acid from elemental sulfur. A series of reports concerning the experimental applications of bacteria on minerals and metallic ores will follow this paper. For several years the Bureau of Mines has been investigating the action of bacteria in the oxidation of sulfide minerals and their potential uses in metallurgical processes. Primary attention has been given to the possible utilization of certain strains of autotrophic bacteria that live in industrial leaching solutions or fractures of mineral outcrops. The purpose of this paper is to acquaint the mining and metallurgical engineer with micro-organisms and some of their possible applications in the field of extractive metallurgy.

Jan 1, 1961

By Kathleen Madland Kowalski

In recent years the issue of human stress response in emergency workers has begun to receive attention. This paper presents a rationale for considering human stress as a significant factor in the management of emergencies It discusses the concept of stress, Critical Incident Stress in emergency responders, and intro¬duces the Critical Incident Stress Debriefing (CISD) process. It is suggested that in a disaster, the CISD process can improve the effectiveness of response teams on site, their turnaround time on site, and post disaster time off the job. This paper, prepared by a US Bureau of Mines research psychologist, offers some ideas to the mining industry in general, mine rescue trainers and more universally, to those responsible for developing emergency management plans.

Aug 1, 1998

By John F. Wiss

A series of controlled experiments was conducted at four surface coal mines to study the effects of certain blast parameters upon the ground and air vibration. Preliminary scale-model blasts were conducted at a quarry to provide basic data. It was found that the amplitudes of the ground and air vibration were controlled by the maximum explosive weight per delay. Either cube root or square root scaling could be used for the seismic amplitudes, and cube root scaling could be used for the overpressure amplitudes. Both amplitudes were not significantly affected by the total charge weight per blast, the attitude of the boreholes, or the charge length or diameter. The overpressure amplitudes were affected by the charge depth, the use of cover over surface detonating cord, and the use of adequate stemming. The length of the delay intervals and the spacing of holes were important in determining the potential for reinforcement of the amplitudes in certain directions from the blasts. In downwind directions from the blast, the attenuation of the overpressure with distance decreases. Surface terrain did not significantly affect the overpressure amplitudes within the range investigated. The type of overburden affects the generation of both amplitudes and the propagation of the seismic amplitudes. Spectral analysis of the ground and air vibration is reported. A scaled distance of 300 ft/lb1/3 should produce a peak particle velocity of less than 1 ips and an overpressure of less than 128 dB linear peak. For square root scaling, a scaled distance of 75 ft/ lbl/2 should limit the ground vibration to less than 1 ips.

Jan 1, 1978

By Peter Grandone

"INTRODUCTION The Bureau of Mines, recognizing the importance of knowing the evapor¬ation losses of aviation gasoline as larger quantities of this material must be stored, has made studies at a large refinery in the Texas Panhandle area during the past 13 months to determine the magnitude of the losses, by evaporation, under different storage conditions. Proper storage of aviation gasoline is very important, not only because large supplies are being stored for military use but because the specifications to which his fuel must conform are very rigid. Aviation gasolines that conform present-day specifications are blended from base-gasoline stocks (in some instances relatively pure hydrocarbons), each of which has different physical and chemical characteristics. Consequently, partial loss of any one of the more volatile components from the blended fuel results not only in material loss of the blended fuel but also may affect the characteristics or performance of the gasoline. One characteristic that has considerable influence or the vaporization tendency of gasoline is vapor pressure; and although the vapor pressure of aviation gasoline usually is lower than that of average commercial motor fuel, the quantity of certain components having relatively higher vapor pressure is greater in aviation gasoline, so that under prolonged storage the evaporation loss of these components may be appreciable."

May 1, 1943

By Thomas E. Green

A solvent extraction procedure using 8-hydroxyquinoline and chloroform was investigated by the Bureau of Mines as a preconcentration technique for the determination of aluminum, calcium, cobalt, copper, iron, lead, magnesium, manganese, nickel, and zinc in large samples of high purity tungsten. X-ray spectrographic and atomic absorption methods were used to determine the trace metals after preconcentration. The presence of 10 grams of tungsten had a pronounced effect on the distribution of 8-hydroxyquinoline between the aqueous and chloroform phases. This change in the 8-hydroxyquinoline distribution in turn had an adverse effect on the extraction of the trace metals. Extraction efficiencies can also be adversely affected by an increase in the quantity of extractable metals present, as shown by radiotracer tests using 65Zn. Excess 8-hydroxyquinoline in the extracts did not interfere with the determination -of the serious interference in the combined ion exchange paper--X-ray spectrographic method. Although preconcentration by 8-hydroxyquinoline extraction was found to be partially successful, other preconcentrationn methods based on ion exchange and dithizone extraction were found to be superior.

Jan 1, 1968

Develop a method for control of groundwater inflow to chronically "wet" sections of underground coal mines, in order to reduce groundwater interference with mining activity and to minimize acid mine drainage. Approach In eastern coal regions, groundwater stored in fracture zones in the rock mass can create a significant water problem for underground mining operations. Fracture stored inflow to mine workings impedes mine productivity since storage water sources usually release at the active face, creating the poor mining conditions typical of a "wet" section. Fracture water can also contribute to AMD problems when the water subsequently contacts sulfide minerals in the coal, The Bureau of Mines has developed a mine-dewatering method that eliminates many of the problems associated with mine water inflow by draining these fracture zones before the water can reach the developing face and interfere with mining activity. How it Works The dewatering method removes large volumes of the stored groundwater through high-capacity pumping from a minimal number of wells placed strategically on fracture traces (the surface expressions of fractured rock zones). These fracture traces are located through low-level aerial photographic and geologic investigation. As shown on the map, dewatering wells are sited precisely on fracture trace intersections in order to take advantage of the increased pumping capacity gained from these zones of high permeability. Once well drawdown indicates that the stored water is depleted,

Jan 1, 1983

By T. H. Jeffers

Significant amounts of cobalt, a strategic and critical metal, are present in readily accessible spent copper leach solutions. For example, recovery of cobalt at two major u.S. copper operations could produce about 1,300,000 lb Co annually, about 13 pct of domestic consumption. However, techniques such as solvent extraction and precipitation have not proven cost effective in separating and recovering the cobalt from these low-grade domestic sources. The Bureau of Mines has devised a procedure using a chelating ion-exchange resin to extract cobalt from a pH 3.0 copper leach solution containing 30 mg/L Co. Cyclic tests in 4-ft-high by 1-in-diam columns gave an average cobalt extraction of 95 pct when 65 bed volumes of solu-tion were processed at a flow rate of 4 gpm/ft2 of resin area. After an impurity scrub, eluates contained, in grams per liter, 0.4 Co, 0.2 Ni, <0.001 Cu, 1.3 Fe, 2.8 Zn, and 0.008 AI. Solvent extraction procedures to remove impurities, reject nickel, and concentrate cobalt produced a cobalt sulfate solution containing 80 g/L Co, 0.05 g/L Ni, and not more than 1 mg/L Cu, Fe, Zn, or AI. Based on data from commercial electro-winning operations, this solution appears suitable for production of metallic cobalt.

Jan 1, 1985

Provide a means of evaluating the in place structural properties of coal seams and coal measure rocks in advance of mining. Approach Develop a sonic logging probe for use in dry wells, a condition common to shallow wells and semi-arid coal regions. How It Works The Bureaus&apos; sonic probe differs from conventional sonic probes because it does not require fluid in the well to couple sonic vibrations to the drill hole wall. A self-contained hydraulic system forces pistons containing the measurement transducers against the wall and clamps them in position until the sonic waveform information has been recorded. The pistons are then retracted and the probe is raised or lowered in the well as required. In the clamped position, the piezoceramic transmitter emits a sonic pulse which travels along the drill hole wall and is detected at the receivers in the form of compressional (P) and shear (S) wave motion. The receivers are designed to be sensitive to either the (P) wave or (S) wave motion as determined by the operator so that discrimination between the two wave types is improved by comparison of the respective output channels, and the travel time between transmitter and detectors can be accurately determined. Use of two receiver stations eliminates errors in timing of pulse travel because of electronic delays inherent in the probe.

Jan 1, 1981

Determine the extent to which remote-sensing techniques, primarily lineament analysis, can be used to identify geologic structures that may affect the location and migration of subsidence over abandoned underground coal mines in the Colorado Springs, CO, area. Compile data using a geographic information system (GIS) to allow efficient and reproducible comparisons and analyses. Background The basis for evaluating abandoned mine land (AML) sites with remote-sensing techniques comes from past and ongoing Bureau ground control research using remote-sensing data to identify potential hazards caused by geologic structures (faults, joints, etc.) above active underground coal mines. Research showed that lineament (linear feature) analysis of Landsat Multispectral Scanner (MSS) images could indicate locations of fractures and fracture trends that had varying, but significant, impacts on the stability of mine openings. Such geologic structures should be identifiable over abandoned mines as well. If fractures are present, even if they arc not faults, they should represent areas of potential instability over these mines and, therefore, should tend to localize subsidence when it occurs, particularly for deep and moderately deep portions of mines.

Jan 1, 1992

Decrease dust concentra¬tions of longwall face workers by keeping them up¬wind of the headgate stage loader and crusher. Approach Direct the face airflow from tailgate-to-headgate, the direction of coal transport. How It Works Ventilation is the primary method of dust control on longwall faces, and the most effective ventilation control is to put workers upwind of dust sources. Recent ad¬vances in longwall dust sampling by the Bureau have shown that on some faces, the headgate crusher and transfer points are signifi¬cant sources of dust -some¬times making up more than half of the total dust to which the face workers are exposed. Also, when the air is coursed from head-to-tail, the relative velocity between the air and moving coal on the face conveyor can cause dust entrainment from the conveyor, particularly if the coal is dry. On the faces where these dust sources are a signifi¬cant problem, they may be eliminated by coursing the air from tailgate-to-headgate, provided that the mine roof is stable enough to permit the necessary intake of the tailgate along with an aux¬iliary intake at the headgate.

Jan 1, 1982