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By A. L. Engel

This report describes laboratory-scale experimental treatment of six base-metal ore samples taken by engineers of the Bureau of Mines, Region II, while investigating ore deposits in California and Nevada. The information is of interest in developing the mining districts represented or when similar ores from other sources are being studied. Simple treatment methods were employed as far as possible. More complex treatments also were tried when necessary. The possibilities and limitations of the methods applied to the several ores are shown by the data herein reported.

Jan 1, 1960

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

Detect fires in or near mine shafts, isolate smoke filled areas, and remotely extinguish fire. Approach A system (of sensors, automatic alarms, an aboveground control console, remotely operated ventilation doors, and sprinklers) has been built from off the-shelf components, and fire, tested in two mines. How It Works The system uses three different kinds of sensors that can detect the heat or smoke of a fire and automatically actuate alarms. When the alarm sounds in the control center on the surface, water sprays in the mine shaft and shaft station areas can be remotely turned on to deluge both the inside and the outside of the mine shaft's wooden support structure. To protect miners from toxic fumes, smoke control doors can be closed or opened, either remotely from the control center or directly by miners using the manual or electrical actuators at the door locations. Man doors built into each ventilation door allow persons to pass without opening the main door.

Jan 1, 1977

By P. Delogne, L. Deryck, R. Liegeois

So far as the propagation of electromagnetic waves is concerned, an underground tunnel behaves like a pipe or hollowed waveguide. Waves propagate in this tunnel with a low attenuation only if their frequency is higher than a so-called critical frequency which depends on the shape and mostly on the cross -dimensions of the tunnel and which value is in the neighbourhood of several tenths of MHz. However, when a metallic conductor is stretched along the gallery the electromagnetic characteristics of the latter are considerably modified and the effect of the cut-off frequency disappears; this is due to the fact that the gallery equipped with such a conductor works like a coaxial cable where the conductor serves as the outward conductor and the wall of the gallery as the return conductor. This is the principle of the monofilar waveguide cable which has been perfectly studied by Gabillard. Two mean characteristics of the monofilar mode are as follows: first of all, when the cable is suspended in the middle of the cross section of the gallery, the electromagnetic field occupies all the space between the wire and the walls of the gallery. When the wire is close to the wall, the electromagnetic field tends to become concentrated between the wire and the wall, with the consequence that, with the given monofilar mode power, the aerial of a receiver standing somewhere in the tunnel will capture a weaker and weaker signal. Secondly, owing to the fact that the mode of monofilar propagation uses the ground as return conductor, its power of propagation is considerably diminished; the closer the wire is to the wall the higher the attenuation, for only a very small part of the wall is utilized as return conductor. To cover great distances, everything else being equal, two or more conductors must be placed in the gallery. If the distance between two conductors of a cable is much smaller than the distance between one or other of the conductors and the walls; or again if one of the conductors surrounds the others and forms a screening, two sorts of modes appear: on the one

Jan 1, 1973

By Travis Q. Lyday

Fiji has been an independent country within the British Commonwealth of Nations since 1970. It consists of an archipelago of more than 300 islands ranging from tiny coral atolls, cays, and rugged coral limestone islets, to the larger mountainous islands of Kandavu, Taveuni, Vanua Levu, and Viti Levu of volcanic origin. The islands of Fiji straddle the 1800 meridian about 1,800 kilometers south of the Equator in the part of the southern Pacific Ocean known as Melanesia. The production of gold and silver from the Emperor Mine at Vatukoula on the island of Viti Levu, the main island of Fiji, remained Fiji's only metallic mineral producer. Mining began at the Vatukoula site in 1933, producing 124 million troy ounces of gold and 147 thousand troy ounces of silver by yearend 1985.

Jan 1, 1987

Improve the dust-control effectiveness of the Rotoclone1 dry-dust collection systems used on surface coal mine drills.

Jan 1, 1994

To more rapidly and economically prepare solutions for chemical analysis, of a wide range of ores, slags, minerals, and metals. Approach A Simple pressure-dissolution system was devised using an inexpensive, heavy wall plastic bottle containing a sample in an acid medium. Using the technique, a complex silicate sample can be dissolved in less than 1 hour. How It Works A weighed portion of a sample, ground to minus 100-mesh, is placed into a polycarbonate or polysulfone plastic bottle. A mixture of hydrochloric acid, nitric acid, and hydrofluoric acid then is added. The bottle threads are wrapped with a layer of Teflon tape to prevent leakage, and the bottle cap is screwed on tightly. The sealed bottle is placed in a balling water bath. In the hot water, the plastic bottle acts as a pressure vessel to contain the pressure generated inside it. This technique should only be used by trained experienced people who are familiar with the hazards of hot acids under pressure. After being cooled in cold water, the resulting solution is brought to the final volume by adding 1.5 weight-percent boric acid solution to the bottle. The cap is replaced, and the bottle and solution is reheated. Precipitated fluorides, as well as any residue, are dissolved by the fluoride-boric acid reaction. The resulting clear solution then is suitable for spectro-photometric examination or other analysis.

Jan 1, 1980

By J. E. Matta

The Bureau of Mines has developed a tracer gas method for measuring leak-age through permanent mine stoppings. In this method, a temporary brattice is erected in the same entry as the leaking permanent stopping. Leakage was evaluated from concentration measurements of a tracer gas introduced into the space between the stopping and brattice. Stopping leakages ranging from 15 cfm to 265 cfm were simulated in an underground coal mine. Leakage values determined by the new method were within 10 pct of the known values.

Jan 1, 1978

By Michael A. Trevits

Mine fires can be especially perilous because toxic products can quickly spread well beyond the fire zone thereby exposing all underground miners to dangerous and deadly conditions. Since November 1998, there have been six major underground coal mine fires or explosions in the United States (Willow Creek (twice), Sanborn Creek, Loveridge No. 22, West Elk and the Jim Walter Resources No. 5 Mine). In each case, the entire mine or specific areas of the mine had to be sealed due to the build-up of dangerous gases and the fear of uncontrolled spread of the fire. Effective placement of mine seals can deprive a mine fire of oxygen and is often followed by water flooding or injection of inert gas into the affected area. When access to the fire zone is impossible because of safety reasons, airtight mine seals can be constructed, in the area of the fire, remotely from the surface through vertical boreholes. Remotely constructed mine seals are commonly made from cementitious material. Since these mine seals are typically erected blindly, it is difficult to determine if mine roof-to-floor and rib-to-rib closure has been obtained. This paper provides a review of the available materials and technology used to remotely construct mine seals through vertical boreholes.

Jan 1, 2002

This section contains a summary of our investigation of the soil conditions (type, porosity, moisture content, etc.) at the two sites (Lanse and Kato, Pennsylvania) selected for field testing of latex as a soil sealant. Other natural conditions such as rainfall, frostline, depth of the water table, etc., were also measured and recorded for possible later use in assessing the effect of the latex seal on the total environment. The numbered sites referred to throughout this report are shown on the maps of the Lanse and Kato sites (Figures 1 and 2). KA, RB and KC are positions at the Kato site - all other numbered positions refer to the Lanse site. Two other terms used throughout the report which should be explained are “horizon” and "profile". These are synonymous terms for soil layer, A horizon (or A profile) referring to topsoil and B horizon (or B profile) referring to subsoil. The properties that control the flow of water through the soil are of special interest because these will also govern the passage of a sealant into and through the soil. Normally the particle size distribution is a good measure of soil permeability, which is directly proportional to sand content and inversely proportional to silt and/or clay content. Tables I1 and I11 show the percentages of gravel or stones, sand, silt and clay of Lanse and Kato soil samples. According to the United States Department of Agriculture classification, the gravel is ,ignored and the residue separated into sand, silt, and clay fractions. Figures 4 and 5 indicate by means of the USDk soil texture triangle that the variability of composition of Lanse soil ranges from sandy loam in the creekbed to clay loam. The variation is even greater among soil samples from Kato. Porosity of soil, also known as percent voids, is another indication of how readily water will travel through soils. Soil density usually increases and porosity decreases with depth, and as expected, the porosity of the top soil at Kato, a forest, is exceptionally porous and open (see Table IV) The pore diameter and length of soil capillaries is extremely variable, and its distribution in the field is impossible to determine. In addition to the capillaries, soil also contains many macro cracks, crevices, and passages around stones and roots. All these affect the flow rate of water through soil. Poiseuille's law states that the rate of flow of a liquid through a narrow tube is proportional to the 4th power of the radius of the tube. Pore size normally decreases with depth and in soil containing appreciable amounts of silt and clay this is especially true. Thus, deeper soils should be less permeable and such was the case at Lanse and Kato.

Jan 1, 1972

By Douglas Talley

This report describes a 4-inch diameter borehole probe which contains a low light level TV camera, magnetic compass, light illumination source, bottom/water detector sensor and a pointing angle sensor. The camera viewing angle is at a right angle to the probe's body. All data from the sensor is multiplexed into the closed circuit camera video for transmission on a single 50 ohm coaxial cable to a surface control unit. Likewise control of the probe's power, zoom lens, focus, panning and aperture is accomplished via a down-link multiplexed on the same cable.

Jan 9, 1984

By E. J. White

Data from oil well logs and core analyses were used to quantitatively evaluate formation porosity and water saturation of heterogeneous carbonates and to study the pore geometry and performance characteristics of cores from these formations. Logs and cores from the Madison limestone from 233 wells in three fields in the Williston basin were used in the investigation. A comparison of log and core analyses shows that log porosities are consistently larger than core porosities, and the differences are correlatable with core porosity ranges. Water saturations from logs are usually smaller than the corresponding core saturations by summation of fluids, but the difference is attributable to mud filtrate invasion into the cores during drilling. Petrophysical studies show that the low permeabilities and high residual water saturations in these reservoir rocks are due to their fine crystalline texture and complex pore geometry (heterogeneity). It is concluded that both log and core analyses must be used for reliable evaluation of these carbonate formations.

Jan 1, 1971

By A. L. Murray, C. A. Allen

"The Industrial Commission of Utah from a study of the accidents (especially the fatalities) occurring in connection with mining in the State was struck by the large number arising from lack of due care on the part of the employee injured or carelessness on the part of some fellow employee. Figures show that approximately 40% of the deaths are due to carelessness as against only ) 10% or 12% that can be laid to faulty conditions in the mines. With a view to reducing the number of these accidents an intensive campaign of education was inaugurated, conducted jointly by the Industrial Commission of Utah and the United States Bureau of Mines.Through the cooperation of the U. S. Bureau of Mines, Mine Rescue Car No. 11 operating in Utah has been utilized as the means of carrying on the campaign. In making the regular training visits to the mining camps of Utah the crew of car 11 was authorized to include with the courses of instruction in Mine Rescue and First Aid, safety and health rallies, foremen's safety meetings, and appeals carried on through the public schools to stimulate an awaking of personal responsibility of miners and their familiar' in safety and health endeavor. The work was placed under the direct charge of Dr. Murray who has had previous experience in similar work and brought to the campaign helpful enthusiasm. He was assisted by Bruce Johnson, fore¬man miner of Car 11, who had been safety engineer for the U. S. Smelting Company, and R. W. Clark, first aid miner of Car 11. The expense of providing posters, literature, pledge cars, buttons, rental of special educational films and incidental expenses of foremens' meetings has been born by the Industrial Commission.Plan of the Campaign.In planning the campaign the main object was to revive as much as possible, among the workers, a spirit of responsibility for safety. Any considerable reduction of preventable accidents can be accomplished only through the workers themselves who are responsible for such accidents, therefore, the more personal the application could be made to all the workers the greater the accruing results would be."

May 1, 1921

Reduce costs of surface mine reclamation by improving scaper operating efficiency and reducing tire costs. Approach The Wheel Slip Monitor senses and compares the peripheral speed of a scraper's four tires 10 the true ground speed of the scraper, and alerts the operator if any of the tires exceeds a predetermined amount of slip. This system helps scraper operators reduce wheel slip during the loading cycle, thereby improving the loading efficiency of the scaper and reducing tire wear and damage. How It Works The system consists of five ultrasonic doppler velocity-sensing devices for measuring the speed of each wheel as well as the true ground velocity (see photograph). Each sensor produces an electrical output signal having a frequency proportional to the speed of the tire or terrain. The signals are conveyed through electrical cables to a control box in the operator's cab where they are converted to voltages proportional to individual wheel speeds (see photograph). The signals are further processed to activate a blinking red light, corresponding to any individual wheel which is slipping, and to sound a beeping tone that is audible to the scraper operator. The rate at which the light blinks and the tone beeps is proportional to the degree of slip. Alerted, the operator can take corrective action.

Jan 1, 1985

To reduce front-end loader (FEL) collision accidents by detecting obstacles in the rear blind area. The Problem Federal regulations require an audible backup alarm to activate when an FEL is backing. Since the device is constantly being activated, the warning soon becomes a normal part of the mine environment and is less effective as a warning device. Also, when several machines are working together, it is difficult to detect by ear alone just which machine is backing. Approach The Bureau defined the location for hazard detection to include an area extending 15 to 20 ft behind the rear bumper of an FEL. Then, existing surveillance and detection technology was assembled, ruggedness, and applied to the FEL's rear blind area to form a new discriminating backup alarm system employing either infrared light, ultrasonics or radar

Jan 1, 1986

By Richard H. Oitto

The Bureau of Mines and Kaiser Steel Corp. are cooperatively demonstrating the shield-type roof support in the longwall mining of a 10-1/2-foot-thick coalbed at the York Canyon mine near Raton, N. Mex. As part of the demonstration, the shield supports have been successfully and safely moved from a completed longwall face to a new longwall face. When these shield supports were moved in 1976 they were the largest and heaviest longwall support system in use in U.S. coal mines. The shield supports, preparations for moving them, the actual move, and installation at the new face are discussed.

Jan 1, 1977

Compare the fire endurance of paneled steel stoppings with that of traditional concrete block Stoppings. Background Permanent stoppings or partitions arc used in mines to separate ventilation airways. The ability of stoppings to retain their structural integrity for a minimum length of time under lire conditions and prevent the spread of flame and toxic combustion products to an adjacent airway is critical. The success of miners in reaching safety during a fire depends largely on the presence of uncontaminated airways. Traditionally, permanent stoppings for coal mines are constructed of concrete blocks. Recently, paneled steel stoppings that satisfy many of the requirements demanded of permanent stoppings, such as incombustibility and strength, have been introduced. Their use also introduced concerns such as the ability of a steel stopping to maintain its ventilation control function when exposed to a fire and the potential that the fire could transmit enough heat through the stopping to ignite combustible materials on the unexposed side. To address these concerns, the Bureau of Mines investigated the fire endurance of galvanized steel and concrete block stoppings.

Jan 1, 1989

By Richard L. Unger

Equipment is the primary cause of injury in 11% of all mining accidents and a secondary cause in another 10%. Purchasers should select new equipment carefully to ensure that the machine incorporates good ergonomic design criteria that maximize the safety of their mine workers. One potential problem area is the workstation-the control center of the machine. Safety problems often occur when the workstation provides insufficient clearance or visibility to the operator or has controls that are difficult to reach. This is especially true for underground mines, where confined space is an issue. In reclined or stooped postures, operators will have less strength and agility and often experience reduced visibility. We have conducted and published much research in Human Factors design of mining machine workstations. This information is currently being compiled into a series of Human Factors design recommendation reports. The reposts dl cover many topics, including workstation layout, control design, seating, and visibility. Each topic has a list of basic or first principles of design. Understanding these principles is the key to designing or purchasing a workstation that is both safe and efficient. Following is a sampling of these main topics and first principles.

Aug 1, 1996

By R. H. Grau, S. B. Robertson, F. Garcia, A. C. Smith, T. P. Mucho

Researchers working for the National Institute for Occupational Safety and Health (NIOSH) at the Pittsburgh Research Center are developing ways to protect the health of miners. Part of that effort is improving the air quality in metal/nonmetal mines by developing proper ventilation techniques. The air quality of large opening nonmetal mines can be greatly improved by using engineering controls of contaminant prevention and proper ventilation techniques. Contaminant prevention includes methods to reduce contaminants from entering the mine air. Ventilation can be improved with appropriate fan selection and fan operation used in conjunction with air coursing using manmade and insitu rock stoppings.

By Margaret R. Egan

In an underground mine fire, a toxic mixture of combustion product gases and particulate matter is transported by the ventilating system endangering everyone downstream. To determine the magnitude of the problem that these toxic combustion products pose, the U.S. Bureau of Mines is investigating the combustion products of typical materials found in underground mines. The total toxicity of the combustion products depends upon the evolving gas species and particulate matter, the amount of material involved, and the ventilation rate. In a simulated mine environment, the products from smoldering poly- vinyl chloride (PVC) brattice and conveyor belting were analyzed for gas concentrations and smoke characteristics. The primary toxic gases are hydrogen chloride (HC1) and carbon monoxide (CO). Smoldering conveyor belts are more detectable than smoldering PVC brattice cloths. These results, combined with previous analyses, are used to estimate relative toxicities, product levels, and detect-ability of smoldering mine combustibles.

Jan 1, 1992