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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 Edward L. McHugh

Digital camera and computer technologies can be used to monitor mine slopes and provide real-time warning of rock falls. NIOSH researchers assembled a surveillance system using low-cost video cameras and computer software from the security industry to test its effectiveness. The system is designed to signal an alarm when motion is detected and to record images of the scene. Masking can restrict motion detection to specific areas within the camera view; sensitivity is adjustable. The time-stamped images provide a record that can help reconstruct and quantify an event. Video motion detection can augment standard monitoring methods to increase safety in surface mines.

To reduce accidents associated with transporting, installing or maintaining mine conveyor belts by providing easy-to-use tools for use in specific tasks. Approach The Bureau of Mines, through a re-search contract, developed three devices for use on conveyor belt systems 1) for use in moving and positioning conveyor components. 2) to reduce spillage and clean-up around conveyors, and 3) to lessen the maintenance of the belt system. The Saucer Skid Moving conveyor components using runner nose 1-beam skids is a simple task when the direction of travel parallels the beams. However, when the unit is moved sideways or around corners for final positioning, the web of the beam scrapes the floor with a bulldozing effect. Many strain and sprain injuries hap-pen when mine workers drag the skids into position at this paint. To minimize such injuries, the Bureau of Mines developed a saucer skid five feet in diameter with rounded sides and a flat bottom. Its design incorporates eight reinforced ribs with holes so the component may be secured to the skid, and eight exterior eyelets to which towing chains may be attached. The skid can be easily moved in any direction because its rounded sides slide over the mine floor rather than drag across it.

Jan 1, 1984

Provide reasonably priced, reliable fire protection for AN-FO haulers. Approach An automatic fire sensing and suppression system for AN-FO haulers was developed and on-vehicle tested. How It Works The system works in two ways to protect personnel from dangerous and unpredictable AN-FO fires. First the system senses and suppresses fires on the truck before they spread to the AN-FO in the bunker. This design was chosen because AN-FO truck fires generally start when combustible liquids (such as diesel fuel, hydraulic fluid or lubricating oils) are ignited by hot surfaces mainly on three areas: the engine, the transmission or the power take-off. These fires are quickly sensed by a linear temperature sensor strung throughout these three areas. The system then warns the operator and automatically suppresses the fire by discharging 30 pounds of multipurpose dry chemical extinguishing agent through a network of fixed hoses and nozzles. Second, this system includes six spot thermal sensors mounted inside the bunker on the truck to monitor the AN-FO temperature in case a fire does spread to the bunker area. If the bunker temperature rises to 190° F, a loud siren is sounded to warn nearby per-

Jan 1, 1981

By James R. Means, George Bowser

A new phone system was developed that provides eight full duplex communications channels over a single twisted shielded phone line, with no central switching station or line amplifiers. This system greatly simplifies installation and maintenance over that required with conventional switching systems. The system is based on microprocessor technology and digital frequency synthesis. Frequency division multiplexing is used over a bandwidth of approximately 300 kHz, and a baseband voice channel (compatible with conventional pager phones) is provided as a backup to assure communication if the multiplex features fail. Multiplex operations are controlled over a 30-kHz digital channel. The system is designed to operate with up to 16 km (10 miles) of cable plant and a maximum phone separation of 8 km (5 miles). The digital techniques permit a limited amount of monitoring and control capability to each phone. This consists of two pair of contact inputs or outputs, to be used as desired. These "flags" may be read or controlled by a dispatcher's phone.

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

8. Refuge Chambers 8.1 Refuge Chambers - Technical Discussion 8.1.1 Introduction As a part of the overall escape system, refuge chambers can provide a last resort when existing escapeways are blocked. These chambers are intended to provide both protection from toxic gases and a life supporting environment for a period of time before external rescue or further escape efforts can be carried out Escapeways may be blocked physically (due to cave-ins, etc), by fire, or by the presence of a toxic or oxygen deficient atmosphere. In the first two cases, the trapped miners would most likely await external rescue efforts, and hence the design of the chamber will have to consider the time durations that such efforts may take, It is also possible, in the second case, for fire fighting and fire protective equipment to be stored in the chamber so that miners may attempt their own escape. In the third case, it should be recognized that a compact, beltmounted 1-hour self-contained breathing apparatus has been developed(9), and that other, less compact equipment is available for up to 4 hours of self-contained breathing supply. If such equipment were stored in the chambers, then miners could escape by travelling from chamber to chamber, taking temporary refuge in each before proceeding to the next. 8.1.2 Background The concept of "barricading" has long been recommended for those emergencies where miners are trapped inby a fire. Barricading, which is the construction of a makeshift shelter in a crosscut or deadend, protects the entrapped miners from toxic gases and enables them to conserve a supply of air. In this manner, they can survive two or three days--hopefully enough time for them to be reached by rescue teams. In the past, many lives have been saved with this technique.

Jan 1, 1976

Predict the spontaneous combustion potential of a coal, using an expert system computer program. Background Approximately 15% of underground coal mint fires in the United States are attributed to spontaneous combustion. These spontaneous combustion fires frequently occur in worked-out or abandoned areas of a coal mine, This makes the control and extinguishment of the fire difficult and often requires large sections of the mine or even the entire mine to be scaled for long periods of time. A prior knowledge of the self-heating potential of the coal can be useful in preventing spontaneous combustion fires through the use of aggressive monitoring and control measures at existing coal mining operations, and in the planning oh new mines. Many factors can affect the spontaneous combustion process in a mine, including the self-heating potential of the coal, ventilation, geologic factors, and mining conditions and practices. Various test methods have been used to evaluate the relative self-healing potential of coals, including crossing point temperature and adiabatic heating methods, and oxygen adsorption techniques. However, these tests arc usually time-consuming and difficult to conduct, limiting their use to laboratories.

Jan 1, 1992

By Charles L. Kimbell

This study is intended to serve three roles. First, it is the second annual edition of this study in a separate volume that represents a global overview and summary to supplement and complement the five regional volumes that now constitute the U.S. Bureau of Mines international, geographically arranged studies. In this regard, it also extends previous works under this title that appeared in the inter-national volume of the Minerals Year-book from the inception of that volume (the 1963 edition) until it was subdivided into six separate volumes in 1989. Following the traditional format of past chapters under this title, the basic statistical presentations herein deal chiefly with 1990, and in a few instances with 1988 or 1989; these latter two only because more recent, comprehensive global statistics simply are not yet available owing to delays in data collection and processing in some countries and continued governmental suppression of data in others. The second role of this study is to provide an update to the coverage of events impacting on the world's mineral industry that have occurred between the end of 1990 and the preparation of this study. Inclusion of this update is almost essential because of the potential effect of some of these events on global mineral industry activities.

Jan 1, 1993

By Robert M. Becker

A thick-wall cylinder solution applicable to the evaluation of anisotropic elastic parameters is derived for the interpretation of stress relief data. For a restricted class of problems, a special relationship among certain orthotropic moduli yields stress distributions for the plane orthotropic problem that are identical to the corresponding isotropic case. A ring or hollow cylinder with these specialized anisotropic properties subjected to uniform radial loads is one of the problems in this class. Consequently, known stress solutions are used to develop the strains and displacements for a specialized orthotropic thick-wall cylinder under uniform pressures. The results are consistent with anisotropic equations used in the evaluation of in situ rock stresses.

Jan 1, 1968

Improve the safety and comfort of operators of large mining equipment. Approach Develop an improved driver restraint system that is easy to use, reliable, and cost-effective, while providing increased protection in the event of a collision or rollover. The Novel Restraint System There are several problems associated with conventional lap-belt type restraint systems. Among these are: restriction of movement, lack of comfort, and fear of entrapment. Standard seatbelts become dirty and oily from lying on the vehicle cab floor and can ruin a driver's clothes. Some haulage equipment may not even have seatbelts available to drivers since they are sometimes removed during maintenance activities or as a result of vandalism. Recognizing a need to address such problems by providing a more acceptable means of driver restraint, the Bureau of Mines designed and fabricated a novel vest-type restraint system. The vest is designed to be worn during a driver's 8-hour shift and would be issued much like safety glasses, hard hats and safety shoes, thus becoming part of the operator's individual protective equipment and assuring that each vehicle has a restraint system when in operation. The vest-

Jan 1, 1985

By Robert L. Lagace, Alfred G. Emslie

This report presents a mathematical model for the propagation of UHF radio waves in the large cross-section tunnels of a room and pillar limestone mine, and describes the analysis of a small amount of propagation data obtained in a limestone mine. The model and analysis is based on the waveguide mode theory developed earlier for the transmission of UHF waves in coal mine tunnels, with allowance for propagation losses due to refraction into the tunnel walls, to scattering by wall roughness, and to long range random tilt of the walls. Propagation around corners and through pillars is also examined based on a ray theory approach, together with the beneficial effects of placing reflectors at intersections to significantly reduce corner losses. The theory is found to be in fair agreement with the data; however, additional in-mine measurements are needed to provide a more conclusive test of the model.

Jan 1, 1979

Control dust generated during undercutting in salt mines without causing ore-solubility problems that result from excessive water use. Approach A foam generator was developed to provide a reliable foam to control dust on cutting machines used in mining water-soluble ores. The system was designed to keep total foaming agent/water mixture flowrates below the flow-rates characteristic of water-only systems. The foam generator consists of a reservoir to hold the premixed agent and water, a metering pump, and a small compressor to aerate the mixture. The system is compatible with all cutting machines. How It Works One of the current wet-bar techniques, the through-the-bar trickle system, pumps water through a pipe in the cut-ting bar to its tip placing the water behind the kerf. If the pipe conducted foam effectively the foam would be released in the kerf where it would mix with the cuttings and the dust produced by the chain. For improved foam delivery, however, it is recommended that the pipe be replaced with an external channel welded along the top of the bar. This provides excellent dust control while avoiding the accumulation of copious quantities of foam in the heading. The system is very simple. The foam generator is a 50-gallon tank filled with a mixture of water and foaming agent. The mixture is pumped through a wye fitting to a second line where it is mixed with compressed air, (300

Jan 1, 1984

By C. Özgen Karacan

Methane emissions from a longwall ventilation system are an important indicator of how much methane a particular mine is producing and how much air should be provided to keep the methane levels under statutory limits. Knowing the amount of ventilation methane emission is also important for environmental considerations and for identifying opportunities to capture and utilize the methane for energy production. Prediction of methane emissions before mining is difficult since it depends on a number of geological, geographical, and operational factors. This study proposes a principle component analysis (PCA) and artificial neural network (ANN)-based approach to predict the ventilation methane emission rates of U.S. longwall mines. Ventilation emission data obtained from 63 longwall mines in 10 states for the years between 1985 and 2005 were combined with corresponding coalbed properties, geographical information, and longwall operation parameters. The compiled database resulted in 17 parameters that potentially impacted emissions. PCA was used to determine those variables that most influenced ventilation emissions and were considered for further predictive modeling using ANN. Different combinations of variables in the data set and network structures were used for network training and testing to achieve minimum mean square errors and high correlations between measurements and predictions. The resultant ANN model using nine main input variables was superior to multilinear and second-order non-linear models for predicting the new data. The ANN model predicted methane emissions with high accuracy. It is concluded that the model can be used as a predictive tool since it includes those factors that influence longwall ventilation emission rates.

By G. V. Sullivan

This report describes an investigation by the Bureau of Mines of flotation techniques for the recovery of chromite from fine-grained disseminated ores. Reported work on the concentration of chromiferous materials shows that flotation has been applied almost exclusively to slime-free pulps. Therefore, chromium recoveries that could be obtained by flotation were related to the amount of slime rejected. However, results of recent studies by the Bureau of Mines showed that des liming is not a requisite to selective concentration of chromite. Laboratory-scale tests on seven ore types from the more important chromium-bearing areas of the Pacific Northwest showed flotation to be technically feasible for treatment of all but one of the samples. Concentrate grades were affected more by the composition of the chromite mineral than by the grade or character of the ore. Test results from three of the samples showed that, without prior desliming of the pulp, 78 to 91 percent of the chromium could be recovered in concentrates of 90 percent or more chromite; two samples responded to similar treatment, resulting in concentrates of more than 80 percent chromite with recoveries of 85 and 89 percent chromium. One sample of mill products, subjected to severe weathering, required removal of the primary slime to obtain a concentrate of 65 percent chromite with only 75 percent chromium recovery.

Jan 1, 1960

By Clarence O. Babcock

ROCK BEHAVIOR has proved of national interest in a variety of fields. The behavior of rock consequent to a nuclear blast was used to detect such blasts, as criteria for the design of underground military defense installations that would resist nuclear blasts, and for judging the feasibility for peaceful uses of nuclear explosives. An obvious peaceful application of nuclear explosives would be for large-scale rock excavation, and plans were presented during the year to improve the present Panama Canal or create a new canal by this method. These plans were based largely on earlier crater tests that demonstrated rock behavior when subjected to a buried nuclear blast. A knowledge of rock behavior under impact was used to evaluate the materials of the moon by means of the geometric configurations visible in the close-up pictures of the moon surface taken by the U.S. rocket Ranger 7. The composition of the moon must be considered in devising methods for taking samples of the surface layers or in designing underground shelters as bases for future explorations of the moon.

Jan 1, 1965

Simplify the spraying of sealants onto coal mine roofs. Approach A nonclogging system in which dry-fed sealant is mixed with water down-stream of the spray nozzle, has been developed and tested. How It Works The two-channel nozzle of this spray discharges two separate flows, a mixture of air and dry sealant from a central cylinder, and an encircling spray of water from a concentrically mounted water ring (a ring-shaped manifold). Downstream of the nozzle, the water mixes with the air and sealant to form a wet sealant spray that adheres to mine surfaces with very little rebound. (See photograph.) Extensively modified commercial spray machines are used to feed the sealant to the spray nozzle smoothly, without raising dust. Plugging of the nozzle is practically eliminated by two self-cleaning design features of the nozzle. These are the air gap and the tapered bore of the cylinder, (See drawing.)

Jan 1, 1979

By Larry P. Jackson

As part of the current research effort in shale-oil chemistry conducted by the Federal Bureau of Mines, reduced chlorophyllins were prepared and pyrolyzed in an effort to identify the role of plant pigments and their decomposition products in the nitrogenous compounds found in the product of oil-shale pyrolysis. The properties of the chlorophyllin pyrolysates were related to the composition of the reduced chlorophyllins with particular emphasis on the amount and types of nitrogen compounds formed. A comparison based on the types of nitrogen compounds present was made betvJeen shale oil and the chlorophyll in pyrolsates. In order to make this comparison, a sample of shale-oil light distillate was separated into polar and nonpolar fractions, and a careful examination of the polar fraction was conducted to obtain an accurate picture of the types of nitrogen compounds present. The information gathered from these studies was used to evaluate reduced chlorophyllin as a model of oil-shale kerogen insofar as the production of nitrogen compounds was concerned. The results indicate that the reduced chlorophyllin does yield nitrogen products which are directly related to the nitrogenous compounds in shale oil, and it therefore represents a good model of shale-oil kerogen.

Jan 1, 1975

By M. E. Tyrrell

The purpose of the work leading to this report was two-fold: (1) To determine the properties of cemented tungsten carbide modified by the addition of one, two, and five percent of titanium diboride, and (2) to compare the properties of these mixtures when sintered, hot-pressed, and flash-welded (resistance-sintered). Minor additions of titanium diboride to mixtures of 94 percent WC and 6 percent Co decrease mechanical strength but increase oxidation resistance in proportion to the amount of the addition. One percent of titanium diboride increased the hardness by 2 Rockwell A units. Hot-pressing produced compacts with the highest density and the best mechanical strength, but losses of cobalt were high and grain growth was pronounced.

Jan 1, 1962

By B. Dimitriades

The Bureau of Mines measured the reactivities of 19 hydrocarbons known to be prominently present in automotive exhaust and ambient air in a smog chamber. Results agreed well with those obtained using two other smog chambers. Reactivity scales were developed for hydrocarbons and aldehydes using the results of this work and those of a previous study. Application of the reactivity scales to automotive exhaust samples gave fair agreement between predicted and observed rate-of-N02-formation values; however, predicted and observed ozone yields were neither in agreement nor did they correlate well. This lack of correlation for ozone yield was attributed to the inappropriateness of (1) the individual component reactivity data, (2) the reactivity classification scheme used, and (3) the linear summation method. In seeking to understand this problem and to develop more appropriate reactivity scales, the data were examined from a reaction mechanism standpoint, and further studies were suggested.

Jan 1, 1975

This Information Circular from the National Institute for Occupational Safety and Health (NIOSH) documents and supplements the information presented in a series of workshops held during 2002 and 2003. The primary intended audience consists of all who are involved in developing and conducting miners? training. According to the Mine Safety and Health Administration (MSHA), mine operators reported 240,000 full-time equivalent workers and independent contractors reported 42,000 full-time equivalent workers working on mine property during the year 2000. Unfortunately, these workers have a relatively high risk of suffering serious work-related injuries and illnesses. The mining industry has the highest rate of occupational fatalities among all U.S. industries. The fatality rate is 30 deaths per 100,000 workers compared to 4.6 for all private industry(Morbidity and Mortality Week Report, 2001; NIOSH, 2002).Compared to workers in other industries, miners also have a relatively high rate of nonfatal lost-time injuries, and their injuries tend to be more severe (Bureau of Labor Statistics, 1999). Many miners are also exposed to significant health hazards, including coal and silica dust, diesel exhaust, and noise. More than 1000 U.S. miners die of lung disease each year(NIOSH, 1999).

Jan 1, 2002