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Provide the mining industry with an easy-to-use means of accurately predicting surface subsidence caused by longwall mining in the northern Appalachian Coal Basin. Approach The Bureau of Mines developed a subsidence prediction model using the novel approach of a variable subsidence coefficient. This approach had to be used because of the resistant strata types which commonly occur within the relatively thin overburden material typical in northern Appalachia. Such resistant strata precluded the use of the popular European methods that assume homogeneous overburden or overburden behaving as homogeneous from a subsidence point of view. The model is available in a BASIC computer program for use on most personal computers. The user has the options of obtaining individual subsidence calculations or may choose to develop a subsidence profile using an average overburden value. The program output can be generated in graphic or tabular form showing the location of the surface point with respect to the longwall panel edge, overburden depth, and the subsidence value.

Jan 1, 1986

Improve the safety, reliability and overall effectiveness of mine stench warning systems and to provide a means of remote control stench injector operation. Approach Industrial gas odorants were analyzed for their suitability for use in mine stench warning systems. A prototype stench injector capable of precise flowrate control was designed, fabricated, and tested using the odorant chosen as having the most favorable properties. Based on the results of the field tests, a second generation injector was developed. The second generation unit features optional remote control operation, and in addition, is simpler to refill and is less expensive than the original injector. A complete second generation system, consisting of two manually operated injectors and one remote controlled injector was in-mine tested through actual mine fire drills. How It Works Ethyl mercaptan mixed with Freon is the predominant stench agent used in the U.S. underground metal and nonmetal mines. However ethyl mercaptan's toxicity,

Jan 1, 1982

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 Donald R. Irving

THIS CHAPTER is new to the Minerals Yearbook and will appear regularly hereafter. Its purpose is to present statistics that reflect technologic trends in the minerals and metals industries (except fuels). Much useful information has been collected annually through the Bureau of Mines mineral commodity and employment and injuries canvasses. However, these data must be supplemented by further data to permit evaluation of the type, direction, and rate of technologic change, which are vitally important in long-term mineral planning. In addition to, and fully as important as, expanding the available data is the need to ascertain that the various items collected are obtained from identical reporting units, to enable direct comparisons to be made.

Jan 1, 1960

By E. G. Valdez

Iron foundries that melt automobile scrap produce flue dusts averaging about 32 percent zinc and 6 percent lead. Some is sold to smelters, but because of the meager return and difficulty in handling, most of the dust is discarded. As part of the Bureau of Mines program to find uses for mineral wastes, research was initiated to develop an economical process to recover zinc and lead from the flue dust. Research encompassed the extraction of zinc and lead by fuming, leaching, and agglomeration. Controlled vacuum fuming of zinc to produce Prime Western zinc and a lead-rich residue was the most effective method for treating the dust. This process involved two distillations, or fumings, with carbon and methane as reductants, and resulted in recovery of 91.4 percent of the zinc in a Prime Western grade product, and 98 percent of the lead. Hydrometallurgical techniques involved several leaching methods, but the simultaneous extraction of iron, manganese, and copper resulted in contamination of the solution and made the zinc recovery processes too complicated. Agglomeration was done by pelletizing or briquetting the dust for possible use as feed to a zinc smelter.

Jan 1, 1975

To provide safer and more efficient mine operations by improving the operational performance of underground trolley line communication systems. Approach The dc trolley line provides a convenient means of In-mine communication since it can carry signals to each phone on the system whether the phones are in mine vehicles or in a fixed location such as that of a dispatcher. In many cases, however, the system does not perform satisfactorily. Short communication range, noise, and dead spots commonly interfere with effective communication. These problems are inherent with the trolley line, which was designed to transmit power and not communication Signals. As a power line, the trolley line is connected to rectifiers and feeds many loads such as motors, water pumps, track block lights, etc. Each of these devices represents a low impedance radio frequency (RF) shunt that seriously reduces carrier communication Signals. Performance is therefore often poor and can be improved only if the effects of the various shunts can be reduced. The Bureau of Mines has developed numerous methods applicable to either existing or planned phone systems which can improve communication range and reduce the shunting effects of the various loads.

Jan 1, 1983

By Helen W. Lang

The Bureau of Mines has developed a very rapid gas chromatographic method for routine determination of oxygen, nitrogen, methane, and carbon dioxide in mine atmosphere samples. Analysis is accomplished in 3 min; readout appears on a single strip chart. The gas sample is split between two columns contained in separate chromatographs. A 5 A molecular sieve column separates oxygen, nitrogen, and methane; a porous polymer column separates carbon dioxide from an air peak. Direct selective analysis of methane from this unresolved air peak is accomplished using a hydrogen flame ionization detector (FID). Carbon dioxide is catalytically converted to methane and detected by FID.

Jan 1, 1972

By M. J. Sapko

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) has conducted full-scale explosion experiments, to evaluate the strength characteristics of various seal designs, used for safely isolating worked-out areas in underground coal mines. Large-scale explosion tests conducted within the multiple entry section of PRL's Lake Lynn Experimental Mine (LLEM) is currently the only accepted test method used by the Mine Safety and Health Administration (MSHA), for deeming a seal design suitable for use in American mines. These explosion tests are labour intensive, expensive to conduct, and can interfere with other critical underground safety and health research programs conducted by NIOSH. The PRL has developed an alternative seal evaluation method, based on a hydrostatic pressure loading concept that can facilitate the in situ testing of seals in an operating mine. Two chambers within LLEM and one within PRL's Safety Research Coal Mine (SRCM) were used for hydrostatic pressure loading various seal designs. The results from these chamber tests compare favourably with those from the large-scale explosion tests in the multiple entries. In addition to testing seal designs at the required 20 psi static pressure level, the chamber test approach also allows for the determination of the seal's ultimate design strength. Six-scaling relationships for predicting the strength of seal designs as a function of entry size are also presented.

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

Objective Develop a method to warn of hazardous conditions and enhance safety during operation and inspection of vertical mine shafts and hoists. Background Mine hoisting is the most critical and potentially the most dan¬gerous operation in underground mining. Many hazards are related to falls of miners and materials, ground instability, and malfunction or lack of safety devices. All have the potential to cause a cata¬strophic accident. A condition known as "slack rope" is particularly dangerous, expecially if it occurs without the operator's awareness. The most common occurrence of slack rope is in metal or nonmetal mines that have a history of ground control problems near the "haft. Approach Studies of hoist safety features and Mine Safely a and Heath Administration (MSHA) accident statistics suggests a need to measure wire rope tension, conveyance speed and position, and shaft guide misalignment. The most accurate data are obtained directly from the conveyance. Such data could warn of potentially dangerous situations during hoisting operations, as well as during inspections, maintenance, and lowering of large equipment. Figure I shows the concept for monitoring wire rope tension, conveyance position, and guide displacement. Progress to Date A conveyance-mounted system has been developed that monitors rope tension: hoist conveyance position, speed, and load; and shaft guide misalignment. A "flex-beam" load sensor mounted just above the- conveyance protects against slack and tight rope. The measurements are transmitted 60 times a second via wireless equipment from the conveyance to the hoist room. An encoder mounted on the conveyance eliminates the need to correct the position because of rope stretch. Figure 2 shows the encoder wheel and guide displacement sensors being mounted on a cage in¬spection deck. A potentiometer monitors misalignment of the shaft guides during inspections. Information about the cage or skip can be acquired by the shaft inspector using a hand-held indicator. Inspection can also he conducted remotely from a station or hoist room using the wireless link to a laptop computer. Figure 3 shows test results from a simulated slack rope condition. Patent Status NIOSH has a patent pending on this device entitled "Cable-Load¬Sensing Device." For More Information NIOSH is seeking cooperators to assist in further tests of this technology to improve hoisting safety. Additional information can he obtained by contacting Michael J. Beus, Steven Iverson, or Elaine Cullen, Technology Transfer Officer, NIOSH, Spokane Research Laboratory, Spokane, WA 99207 at (509) 354-8000.

Feb 1, 1998

By Collin Stewart, Greg Hunt, Christopher Mark

Bowie Resources maintains one of the most pro-active ground control programs in the U.S. mining industry today. Its guiding philosophy is that everyone in the organization, from the miners at the face all the way through the top management, are involved in ground control. Some of the unique elements of the Bowie ground control program include: • Roof bolt operators log the stratigraphy of test holes in nearly every cut. These “lith-graphs” are used by section foremen to determine the need for additional roof support, and they are entered into the geologic data base for use in geologic modeling and mapping. • Underground core drilling is conducted to obtain data for CMRR and stability maps. • Weekly “Quality” meetings, involving mine management and technical staff, are held to ensure that ground control information is integrated into production operations. The paper will describe the program in detail, discussing the involvement of roof bolters, section foremen, surveyors, technical staff, and production managers. It will also show how the program has contributed to the mine planning process. Case histories of successful ground control interventions will be discussed.

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 J. J. Cummins

The Bureau of Mines heated at 150° to 350° C for 0.5 to 360. days Green River oil shale that had been previously extracted by benzene to provide information on in situ processing conditions, to determine the effect of low-temperature heating on the unconverted kerogen, and to determine the composition of benzene-soluble thermal products. The methods used in determining the composition of the soluble thermal products consisted of fractionation of the soluble material, elemental analysis of the soluble products, fractionation of the polar resins by ion-exchange chromatography, gas chromatographic analysis of [n]-alkanes3 and mass spectral analysis of the branched plus cyclic alkanes and aromatic oils. The methods used to determine the effect of low-temperature heating on the unconverted kerogen remaining in the oil shale heated residues consisted of carbon-hydrogen analysis, volatile material determination, carbon residue determination, and oxidation rate determination. In general, it was concluded that significant increases in the degradation of kerogen to oil occurred between the temperature range of 250° to 350° C; that the composition of the soluble products depends upon the temperature at which they are formed; and that the [n]-alkanes are pyrolytically degraded from the kerogen structure. In particular, the 250° C heating temperature is beneficial to the formation of branched plus cyclic alkanes. Also, the heated and unconverted oil shale kerogen and the soluble thermal products become more aromatic as the temperature increases from 150° to 350° C.

Jan 1, 1974

By Geo S. Rice

"Three men lost their lives in the Black Diamond Coal Mine near Seattle, Wash., recently while wearing oxygen breathing apparatus. The press dispatches stated that these men lost their lives while practicing with the apparatus. Later reports stated that the men died while attempting to make a trip 1200 feet down a 25 degree slope which was filled with black damp, in order to measure the amount of water that had accumulated at the bottom of the mine, and the trip was attempted with oxygen in the tanks of the apparatus with dials indicating only 45 minutes supply. The oxygen in the tank was used up and the men therefore lost their lives from a deficiency of air to breathe.In spite of all the education and training done by the Government to prevent accidents, men are prone occasionally to take unnecessary chances. Every piece of apparatus, no matter how perfect, has its limitations. The Government, through the agency of the Bureau of Mines, has trained many thousands of miners in the use of mine rescue apparatus. The training has been given to all miners who requested it, and the Bureau has gone to the extreme of urging miners to join the rescue and first-aid classes. In spite of all the efforts of the Government, men occasionally attempt the impossible."

Jul 1, 1920

By Michael J. Brnich

Since 1991, Pittsburgh Research Center (PRC-formerly part of the Bureau of Mines) researchers have recorded extensive interviews with 30 individuals who are experts in the area of mine emergency response. These individuals, who have an average of 35 years of mining experience and 29 years of mine emergency response experience, related stories and observations from events that they experienced during their combined 850 plus years in mine emergency response. The purpose of this effort was to gather information that could be passed on to both today?s and tomorrow?s mine emergency responders to train and guide them in handling future events. This is the first of two articles which report the responses that these experts gave when asked how they think people who may have to respond to a future mine emergency should be trained. During the interviews they discussed how training should be conducted, who should be trained, and what topics should be included. This article will cover the first two areas: what training methodologies would be most effective and who needs to participate.

Jan 1, 1997

By Jack C. White

Studies were made to determine the character and distribution of the copper lost in copper mill tailings. Acid soluble (oxide) and acid insoluble (sulfide) copper were determined for heavy-liquid sink and float products of screen-sized fractions from 12 copper mill tailings. In most of the tailings studied, the coarse-size fractions are higher in copper grade than the respective bulk tailings, high in sulfide copper, and low in oxide copper. Oxide copper occurs predominantly in the minus 325-mesh "slimes." Microscopic examination of heavy-liquid sink products indicated that recovery of liberated copper sulfide minerals is complete in most mills, and that copper minerals not being recovered are locked with gangue particles. Additional copper could probably be recovered from most tailings by size classification, scavenger froth flotation of the coarse fraction, and regrinding of the concentrate to achieve liberation of the locked sulfides.

Jan 1, 1971

By D. E. Seizinger

Analytical methods for oxygenates in exhaust gases were studied, and emissions of these compounds from automotive engines were measured with and without an oxidation catalyst in the exhaust system. Hydrocarbons, simple mixtures of hydrocarbons, and a single gasoline were used as fuels. With the more complex gasoline, successful analysis was possible only with exhaust from the catalytic system which preferentially converted and thus removed interfering hydrocarbon species. However, it was shown that an estimate of the oxygenate yield from gasoline used in a noncatalytic system can be synthesized from data obtained with simple fuels. Such synthesized data were used for comparison of noncatalytic with catalytic systems. Compared with those of previous studies, results of this work indicate that the action of the catalyst introduced no new oxygenates and reduced both the carbonyl and the total of oxygenates. It is concluded that the compositional character and class distribution of oxygenates in exhaust from catalytic systems may differ significantly from the composition and distribution for oxygenates not subjected to catalytic conversion. The findings also support previous estimates that noncarbonyls may constitute a significant fraction of exhaust oxygenates and may warrant attention in procedures for measurement of the oxygenates.

Jan 1, 1973

Provide a lighter, smaller apparatus for more gently supporting electrical cable as it is raised or lowered in a well as compared with the conventional method of using a winch and pulley. Approach The conventional method of running cable into a well is to use a winch to pull the cable over a pulley located at the end of a boom placed over the well. This has the disadvantages of being bulky and of placing a concentrated strain on the cable at the point where it moves over the pulley. These disadvantages are overcome by using a "Chinese finger" cable grip assembly to hold and release a multiple conductor cable.

Jan 1, 1986

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 R. V. Ramani, R. Stefanko, G. W. Luxbacher

Computer input data for an operating mine is developed on the basis of a detailed ventilation survey which includes air quantity, air quality, pressure loss and fan performance measurements. Quantity measurements must be reviewed extensively and assumptions made about leakage quantities and airflow paths. Pressure measurements must be reviewed and developed into a pressure gradient for the mine system. Air quality measurements are used to determine methane sources and amounts. Finally, the fan test data is used to develop the correct fan characteristic curve. Quantities and pressure losses for each branch in the system are used to calculate the branch resistances which are then utilized in the ventilation simulator to model the mine system. QUANTITY BALANCE The quantity of air coming into a mine based on field measurements will rarely equal the quantity exiting the mine, even if allowances are made for methane or compressed air input to the system. The same statement can be made for airflow through any isolated part of the mine ventilation system such as individual working section or main aircourses leading to an area isolated from the rest of the mine. The reason for the apparent discrepancies is the accuracy of the indicated quantities which in turn is based on the accuracy of the individual velocity and area measurements. Even with measurements following the guidelines described in the previous section on quantity measurement, this error can only be minimized but not eliminated. As a result the ventilation system must be carefully balanced so that, for any loop, the quantity in plus any methane or compressed air injection will equal the quantity out. The continuity of flow described by the balanced system must approximate the

Jan 1, 1977