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By Ben A. Kornhauser

The mineral industry consisted primarily of natural gas production and of urea fertilizer, which was manufactured for domestic agriculture. Copper and iron deposits were being developed. Information regarding the mineral industry of Afghanistan was sparse. The Government continued to emphasize the development of mineral resources that could benefit the economy of the U.S.S.R. and repay Soviet grants. The northern half of the country, north of the Hindu Kush mountain range and adjacent to the U.S.S.R., received considerable Soviet aid to develop mineral resources.

Jan 1, 1986

By Richard V. Ageton

"Everyone admits that there are more accidents in metal mines than there should be but there is much difference of opinion as to the causes of accidents, whether avoidable or unavoidable, and the amount of responsibility attaching to the miner and the mine operator, respectively. However, it seems that one of the main reasons why there are so many accidents, is that there is so little general knowledge regarding their causes and costs. Some information regarding the costs and causes of metal-mine accidents is presented in this paper.The data contained were obtained from a study of the complete accident and medical reports of two large metal-mining companies, which carry their own insurance. Path maintain hospitals with competent medical attendants. One of these companies also maintains a very efficient safety bureau, consisting of a safety engineer, with two assistants who work in connection with the medical department, and with the safety committee made up from among the miners themselves.Daring the year of 1920, ""A"" Company employed approximately 900 men, and these men worked more than 270,000 shifts. There were 373 minor and major injuries, among these 900 men, hence assuming that each injured man was hurt cut once, 41 per cent of the men who worked in this mine received some kind of time-losing injury during the year. On account of these injuries the injured men lost 3731 shifts, and thus the time lost due to injuries amounted to approximately 1.4 per cent of the total number of shifts worked,"

Oct 1, 1923

By Joseph V. Mather, E. H. McCleary

"INTRODUCTION Workmen are transported in shafts in various types of cages or skips, most of which were designed primarily for hoisting cars and materials. Therefore, in general the cages or skips are not completely enclosed, adequate and gates are not always provided, and at many mines signaling devices and telephones are re¬stricted to those at the various landings in the shafts.Shaft accidents are usually severe - frequently fatal - and as a rule such an accident is caused by failure to comply with company rules or by ignoring them.Sixty men were killed and 555 men were injured in shafts of the anthracite and bituminous coal mines of the United States during the 5-year period 1938-42. 4/ Many of these accidents could have been prevented by having properly enclosed cages and adequate locking devices on doors to prevent workmen from falling into the shafts.The officials of the Heidelberg Coal Co. contemplated utilizing an old coal-hoisting shaft as a man-hoisting shaft; however, it was their desire to avoid the use of the conventional cage and to try to provide a safer means of transporting men in the shaft. Investigations and studies made by the officials revealed that an elevator similar to those used in large buildings would be more economical in first cost, maintenance, and operating costs would be less, and it would be safer and more convenient for the workmen. Effective safety devices for such elevators have been developed to such a high degree that those properly installed seldom fail. The elevator or man cage finally chosen cannot be pulled above the top landing through mechanical or man failure; it stops automatically at each landing and cannot be moved while a door is open; when the cage leaves the landing the doors opening to the shaft are automatically locked by mechanical and electrically operated locks; electric lights, telephone communication, and push-bottom controls are available on the cage, and adequate safety switches and overspeed controls are provided."

Jun 1, 1947

Reduce the number of accidents caused by slips and falls from large mining equipment. Approach A powered lift was developed that provides operators with a safer way of getting on and off large machines. How It Works The powered step is designed to lift personnel and materials to working levels on large machines. It eliminates hazardous blind steps and makes it unnecessary to climb on irregular surfaces made slippery by mud, ice, snow, and accumulations of grease. The step is powered by a self-contained electric/hydraulic unit which is connected to a vehicle's auxiliary power supply. When in the "down" position, the step rests about 15 inches above ground level. When the power unit is activated with an electrical switch located on the step, a Single cylinder attached between two lifting arms smoothly lifts the step. In conjunction with the lifting motion, a linkage and bearing arrangement on the mounting end of the lift arms causes the step to rotate towards the machine, so that the step moves in an arc from ground to platform level. When the machine Is operating, the step is automatically locked in the "up" position, protecting it against any damaging contact with obstructions. The step is lowered by activating a pressure release solenoid. An in-line orifice controls downward speed and prevents free fall. On most machines, additional control switches are conveniently located at ground level and in the operator's cab. Visual alarms and machine interlocks are provided where necessary to prevent machine operation when the step is In the "down" position. The powered step can be easily adapted to any type or model of large machinery.

Jan 1, 1981

Reduce workers' dust exposure by capturing airborne coal and quartz dust generated by a continuous mining machine. Approach Install a water-powered scrubber system operating at 1,000 psi on the boom of a continuous miner at the conveyor throat. Dusty air from the face area is drawn through the scrubber and cleaned air discharged into the return. How it Works Most coal mines use exhaust face ventilation to send fresh air over the miner operator and contaminated air behind the line curtain to the return. The problem with exhaust ventilation is that the line curtain should be within 10 ft of the face for maximum effectiveness. If the line curtain is not extended properly, or water sprays for dust control are poorly installed, dust rolls back towards the operator. An effective way of removing this dust is with a scrubber mounted on the mining machine.

Jan 1, 1988

To develop a simple device for rapidly determining the shearing strength and angle of Internal friction of coal and rock in situ. Approach Use a portable, permissible, hydraulically operated device in boreholes as deep as 100 feet into the rib, floor, or roof of the mine. How it Works The device, called a Borehole Shear Strength Tester (BST), is inserted Into a 3-inch-diameter borehole to the desired depth, locked Into position, and activated to shear the rock or coal in the borehole walls. The normal and shear pressures exerted by the BST, which are recorded during the test, are used to calculate the shearing strength and the angle of internal friction. The BST consists of 3 main components and several minor components. Main components are: ? A shear head with 2 shear plates that bite into the rock when normal pressure is applied. ? A hollow hydraulic jack with RW drill rods that pull the shear head when shear pressure is applied. ? A console with a hand pump and two hydraulic gages to activate the device and to indicate the pressures that apply the normal and shear faces to the shearing plates.

Jan 1, 1981

To rapidly limit and interrupt high dc fault currents with minimal arcing in the mine atmosphere. Approach Design a dc switching sys-tem which uses a pressurized, liquid metal-filled, change-of-state device combined with a conventional interrupter and commutating switch. Direct Current Interruption Switching and interruption of large direct currents imposes severe loads on fuses, contactors, and circuit breakers in mine power systems. This problem is much more pronounced with de than with ac because of the lack of a natural current zero in dc. Dc interruption is characterized by persistent arcing that can foul contact tips and con-tribute to interrupter failures. To reduce maintenance and prolong the service life of these units, a commercially viable dc switching system has been developed by the Bureau of Mines through a research contract with the University of Pittsburgh. This system rapidly limits and interrupts high fault currents when used in combination with conventional interrupters.

Jan 1, 1983

Rapidly identify unstable mine waste embankments and similar dam structures. Approach Aerial photography, geotechnical instrumentation, and telephone or satellite data transmission are used to supplement walk-around inspect ions. How It Works Embankment stability and other indicators of structural integrity are evaluated using aerial photography, and on-site unattended instruments and data transmitting systems. Evidence of external movement and water seepage is obtained from aerial photography and photogrammetric evaluation techniques. Surface points marked by stake- mounted targets are monitored photographically at time intervals of several weeks or months. Photographic measurements of x, y, and z coordinates of these points are obtained from flying a series of photo-runs over the dam.

Jan 1, 1979

By Charles C. Boley

The Bureau of Mines dried and carbonized two wood wastes, one softwood (redwood) and one hardwood (oak), using continuous, vertical entrainment techniques previously developed for use with coal. It was demonstrated that these techniques are readily applicable to wood waste and that appreciable changes in the yields of carbonization products can be obtained by varying operating conditions. A limited amount of experimental work was done on briquetting the charcoals. Firm briquets were formed with oak charcoal, although greater quantities of starch binder than used commercially for kiln-produced charcoal were required. Redwood charcoal did not briquet successfully under the test conditions employed.

Jan 1, 1969

By S. M. Shelton, W. A. Calhoun, M. M. Fine, T. L. Johnston

"This report is () expansive test program by the Bureau of Mines to determine methods from various and ferrous manganese-grade product () widespread () and manfniferrous iron ores. Among the samples received for testing was one from the pits of the Barytes Mining Co., 1-1/ 2 miles northeast of Cartersville, Ga.. The property is approximately in the center of the Cartersville manganese district and shares a common corner with properties of the New Riverside Ochre Co. and the Etowah Development Co., both producers of manganifereus ores. The deposit is typical of the district and occurs in residual clays resulting from weathering of the Shady limestone and Weisner quartzite. 7/The property is developed by a number of open pits ranging to 60 feet in depth. In 1918 several carloads of manganiferous iron ore was mined from an alit on the property. Since then mining operations have been negligible. The ore is known locally as calico ore.A 4-ton sample representing -re as it occurs in the -pen pits vas furnished for testing. The sample consisted of a mixture of red iron oxides, wad, and clay, with small pebbles of manganese oxides and siliceous fragments scattered throughout."

Mar 1, 1943

By W. H. Eddy

Laboratory batch and small-scale continuous flotation tests were con-ducted by the Bureau of Mines on a mica waste tailing from Kings Mountain, N.C., to determine the feasibility of producing high-quality mica, feldspar, and glass sand. Mica was recovered by two methods; one was by flotation in an alkaline circuit, which produced a mica concentrate assaying 92.0 percent mica with a recovery of 87.l percent, and the other by flotation in an acid circuit, which produced a mica concentrate assaying 91.0 percent mica with a recovery of 79.4 percent. Continuous flotation processing yielded a feldspar concentrate assaying 1.10 percent Na20 and 13.50 percent K20, with recoveries of 66.4 and 80.6 percent, respectively. The feldspar tailing was high-quality quartz glass sand analyzing 98.6 percent Si02 and 0.02 percent Fe203.

Jan 1, 1969

By J. M. Stuve

The standard heats of formation (?Hf°) of holmium trichloride and terbium trichloride were measured by solution calorimetry. Heats of solution of holmium and terbium metals and their anhydrous chlorides were measured in 4.360 molal HCI at 298.15° K. From these measurements ?Hf° for HoC13 (c) was calculated as -240,290 ±1,700 cal/mo1e, and ?Hf° for TbC13 (c) was calculated as -238,330 ±1,500 cal/mole at 298.15° K.

Jan 1, 1967

By Wilbur I. Duvall

In this report, the Bureau of Mines presents a theoretical solution for the stresses and displacements in an infinite elastic plate containing a circular hole the boundary of which is loaded by applied radial stresses over four separated arcs. The problem solved is a two-dimensional approximation of the stresses and displacements developed by a large tunnel-boring machine anchored in a circular tunnel. Analysis of the solution shows that the tangential tensile stresses induced on the boundary of the circular opening can be minimized in the roof and maximized in the floor of the opening by proper spacing and loading of the four arcs.

Jan 1, 1967

To improve the efficiency and speed of under-ground post-disaster rescue operations. The Approach: Develop a battery-powered mine-rescue vehicle designed to carry rescue crews, rescued miners, and their support equipment. How It Works: The experimental vehicle, shown below, was designed and constructed by the Mine Safety Appliances Company under contract to the Bureau of Mines. ATV Manufacturing Company and Delco Electronics were subcontractors. A rechargeable, silver-zinc battery provides power to a 3-horsepower permissible motor, the speed of which is regulated by a solid-state controller. Three wheels on each side are independently driven by a chain and mechanical trans-mission.

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 D. R. Forshey

The recent occurrence of fatal accidents in copper mines, presumably due to premature ignition of loaded holes by the heat from reacting ammonium nitrate-fuel oil (AN-FO) and pyrite-bearing ores, has led to an examination of this reaction. The reactivity of prilled AN-FO mixtures with pyrite-bearing ores and the effects of water, dilute sulfuric acid, and potential inhibitors on reactivity of the mixtures were evaluated. Initiation of an exothermic reaction was observed as low as 150° F with acid in the absence of inhibitors. Low concentrations of urea, calcium carbonate, zinc oxide, and magnesium oxide were effective in inhibiting the reactivity of the mixtures. The temperatures produced during the reaction of mixtures of AN-FO and pyrite-bearing ores, in the absence of inhibitors, always exceeded the temperature at which electric blasting caps are thermally initiated.

Jan 1, 1968

By Richard Mainiero, James H. Rowland

For many years there have been small scale tests available for evaluating the toxic fumes production by cap-sensitive explosives (DOT Class 1.1), but these could not be used with blasting agents due to the large charge sizes and heavy confinement required for proper detonation. Considering the extensive use of blasting agent in construction and mining, there is a need to determine the quantities of toxic fumes generated by blasting agents. At the International Society of Explosive Engineers Twenty Third Annual Conference on Explosives and Blasting Technique in 1997, the authors reported on a facility for detonating large (4.54 kg), confined blasting agent charges in a controlled volume that had been constructed at the National Institute for Occupational Safety and Health’s Pittsburgh Research Lab’s Experimental Mine. Since 1997, this facility has been used to collect data on toxic fumes produced by the detonation of various ammonium nitrate/fuel oil (ANFO) mixtures and several cap-sensitive explosives. ANFO composition ranging from 1 to 10 percent (pct) fuel oil have been studied. As expected from previous studies, with an increase in fuel oil content the carbon monoxide production increases, while nitric oxide and nitrogen dioxide production decrease. The detonation velocity varies from 3,000 to 4,000 m/sec for the 1to 10 pct range of fuel oil content, suggesting that ANFO mixes with improper fuel oil content may appear to detonate properly, while their fume production differs significantly from optimum. The study also considers such factors as degree of confinement, water contamination, and aluminum content on blasting agent fume production. Results indicate that water contamination of the ANFO has little effect on carbon monoxide production, but causes significant increase in nitric oxide and nitrogen dioxide production. Decreasing confinement from Schedule 80 steel pipe to 0.4-mm thick sheet metal also has little effect on carbon monoxide production, but significantly increases nitric oxide and nitrogen dioxide production. Adding5 and 10 pct aluminum to the ANFO had no clear effect on carbon monoxide, nitric oxide, or nitrogen dioxide production.

By D. D. Bolstad

The Bureau of Mines has developed procedures for sampling the geometry of fractures in underground coal mines. Stratified cluster sampling and the unit area concept are applied to the collection of fracture orientation data. The use of unit area mapping, stratification, and site delineation is made to assure collection of representative data. The procedures developed here help to isolate sources of variability in the fracture patterns.

Jan 1, 1973

By John C. Edwards

To have the capability to predict the development of localized spontaneous heating within a porous coalbed that is subjected to forced air ventilation or in an otherwise quiescent environment in which buoyancy develops, the Bureau of Mines developed three time-dependent mathematical models, which were used to calculate the temperature increase associated with chemisorption of oxygen by the coal. In each model, spontaneous heating is driven by an Arrhenius first-order reaction between the oxygen and coal. Two models are two-dimensional, and one is one-dimensional. In the first two-dimensional model, a constant-velocity forced convection airflow is specified; and in the other, buoyant flow is allowed to develop in the absence of forced convection. The third model evaluates the airflow from Darcy's law and a specification of the pressure at the surface of a one-dimensional porous coalbed. Numerical computations demonstrated how each model could be used to predict the onset of spontaneous heating when the porous coalbed was subjected to constraints of an imposed internal heat source or a high- temperature airflow. The effects of particle size and coalbed compaction upon spontaneous heating were examined with the third model.

Jan 1, 1990

Develop a user-friendly, personal computer-based numerical modeling program that performs structural analyses of underground tabular deposits, making these readily available to the mining industry. Background When ore is extracted from an underground mine, the overburden weight is redistributed to unmined areas, recompacted gob zones, and artificial structures such as packwalls and/or cribs. This redistribution of stresses continually changes throughout the mining cycle and can be especially complicated when multiple-seam mining is involved. Numerical mine structural analysis methods provide a way of calculating the redistribution of overburden stresses and the resulting loading for any given area of an underground mine, thus enabling engineers to design safer and more productive mines. In 1973 Crouch and Fairhurst developed a mine structural analysis computer program called MINSIM. This computer program was based on the three-dimensional displacement-discontinuity approach, a subvariation of the boundary-element method. In 1979 Sinha expanded MINSIM's capability to provide an analysis of parallel multiple seams. Sinha called his program MULSIM. During 1984 and 1985, the Bureau of Mines upgraded and completely restructured MULSIM into what is now called MULSIM/BM.

Jan 1, 1990