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By Stephen Krickovic

A methane emission rate study was conducted in 1969 on a longwall section of a Lower Kittanning coalbed mine in central Pennsylvania. The longwall face was mined with a drum shearer between developed headings on the head end and headings on the tail end that were driven with a ripper-type continuous miner as needed. The study was conducted over 22 consecutive shifts (7-1/3 days). The average methane emission rate from the Lower Kittanning coalbed during mining at the face and developing the headings at the tail end of the face was 34 Am. Caving of the gassy overlying strata as the result of mining at the face increased the methane emission to rates ranging from 702 to 1,049 cfm.

Jan 1, 1971

By D. J. Parker

Du.ring the past two years a number of oases of successful first-aid treatn . .)nt have been reported by or through the employees of the O. s. Bureau of -anes safety cars and stations. Among such cases are the following: At Benbush, w. Va., a boy or 16 years of age who ba.d just started to work in the mines was trained in first-aid by the crew of Bureau of Mines car 8. The local rr.ine superintendent afterwards reported tba.t a few dS¥s later this boy, Melvin Hollingsworht, found droming in a spring a. baby about three years old who bad wandered away fron.. har.e alone. The boy rescued the baby and perf'oxmed artificial re­suscitation upon it, thu.s saving the child's life. The Schaefer method of resuscitation bad bean ta"Ugbt the boy as a routine art of the regular first-aid course.

May 1, 1922

Minimize airborne respirable quartz dust produced by continous mining machines. Approach Install a shovel-mounted underboom water spray system on the off-curtain side of the mining machine. Dusty air containing quartz is momentarily trapped under the boom, where it is captured by fine spray mist. The remaining dust cloud is directed immediately behind the curtain before it can migrate back to the machine operator's location. How It Works Previous studies have shown that most of the dust generated by continous mining machines occurs under the boon as the cutter head shears down. The primary source of respirable quartz dust on many continous mining operations is cutting or trimming roof rock immediately prior to shearing. This results in very high concentration , of

Jan 1, 1989

By L. B. Pankratz

Enthalpies above 298° K were investigated for four crystalline sodium borates by copper-block drop calorimetry. Determinations were made to 1,200° K for NaB02, 1,003° K for Na2B407, 1,005° K for NaB305, and 1,046° K for Na2Be013. No phase transitions or other thermal anomalies were found. The enthalpy determinations, when combined with known heats of formation at 298° K and other supplementary data, enabled the calculation of the heats and free energies of formation of the compounds to their melting points. Values of relative enthalpies, entropies, heat capacities, free energy functions, enthalpies of formation, free energies of formation, and equilibrium constants of formation were tabulated at even temperatures.

Jan 1, 1971

By J. L. Ellenberger, P. W. Jeran

A deep longwall coal mine was instrumented with a three-dimensional microseismic system in order to help determine the exact strata mechanics associated with the rock failure, redistribution of stress and the associated gob formation from the longwall. Overall, 5,000 well calibrated seismic events were recorded during the mining of the panel. Analysis of these events showed a close correlation between the seismic activity and advance rate, and that the majority of the recorded seismic activity occurs in the immediate area of the advancing longwall face.

By Fred N. Kissell

Tracer gas decay curves were experimentally obtained in a full-scale model coal mine working face area. The concentration of tracer gas was found to decay in exponential fashion but with a change in slope. This change in slope is attributed to eddy zones in the face area. A simple theory was developed that allows one to calculate the approximate amount of gas in the eddy zones and thus estimate the size of the eddy zones.

Jan 1, 1974

By L. A. Johnson

The Bureau of Mines analyzed three cores from the south Seep Ridge area of the P. R. Spring tar sand deposit of northeastern Utah. Four tar sand zones are indicated in the area. The zones range in average thickness from 13 to 24 ft. The total net thickness of the tar sand in the three coreholes ranges from 71 to 112 ft. The tar sand occurs between the depths of 27 and 254 ft. It has good porosity, 25.6 pct of bulk volume; high permeability before and after oil extraction, 819 and 2,218 md, respectively; but a relatively low oil saturation, 36.5 pct of pore volume. Gravity of the oil ranges from 8.20 to 16.5° API.

Jan 1, 1975

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

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

Jan 1, 1982

By D. R. Tesarik, R. W. McKibbin, J. B. Seymour

Displacement and stress changes in cemented backfill and ore pillars at the Buick Mine, near Boss, MO, were monitored by engineers from the U.S. Bureau of Mines and The Doe Run Co., St Louis, MO. A test area in this room-and-pillar mine was backfilled to provide support when remnant ore pillars were mined. Objectives of this research were to evaluate the effect of backfill on mine stability, observe backfill conditions during pillar removal, and calibrate a numeric model to be used to design other areas of the mine. Relative vertical displacements in the backfill were measured with embedment strain gauges and vertical extensometers. Other types of instruments used were earth pressure cells (to identify loading trends in the backfill), borehole extensometers (to measure relative displacement changes in the mine roof and support pillars),and biaxial stress meters (to measure stress changes in several support pillars and abutments). Two- and three-dimensional numeric codes were used to model the study area. With information from these codes and the installed instruments, two failed pillars were identified and rock mass properties were estimated.

Jan 1, 1995

Provide exhaust face ventilation to remotely-controlled continuous mining machines making extended advances without exposing workers to unsupported roof. Approach Modify the sprayfan to move additional air to and from the coal mine face. Unmodified, sprayfans are capable of ventilating the face with 20-foot brattice setbacks. Additional sprays on the rear of the mining machine allow setbacks to be extended up to 40 feet.

Jan 1, 1988

By A. Mayton, A. Brien, W. Porter, O&apos

In 2004, management at Unimin's Gleason, TN operation began implementing ergonomic interventions specifically targeted to reduce risk of musculoskeletal injuries (MSIs). Together with corporate and site management, Unimin identified work site hazards and began to modify work practices/equipment. Some interventions were relatively simple and were implemented immediately. Others, like improvements to a mobile shredder, were more complex but were eventually resolved through a participatory approach with employees, management, manufacturers and NIOSH. This paper discusses ergonomic interventions that were successfully implemented using a bottom-up approach to reducing the risk of injury.

Hang ventilating air curtains so that they can be installed, moved, opened and closed more easily than curtains that are spadded or nailed in place. Approach Low-leakage plastic curtains fitted with grommets along the top were threaded onto a steel cable which is suspended from roof bolt plates. The system was tested in two mines. How It Works The curtains are threaded onto a steel cable which is suspended from roof bolt plates by S-shaped hooks. See Figure 1. The outby end of the cable is reeled off a hand operated winch; the inby end of the cable is anchored to a roof bolt plate by means of a cable grip and an S-shaped hook. To install the curtains the following procedure is used. First, the winch is located at least 5 feet outby the last open cross-cut. The base of the winch can be secured to the mine roof with short roof bolts, only about a foot long.

Jan 1, 1978

Assist in controlling or extinguishing fires that occur in abandoned mine lands (AML) by providing a compilation of information on past fire control projects, the estimated extent of the current problem, and factors affecting the occurrence, propagation, and extinguishment of AML tires. Conventional fire control methods and their probable effectiveness are evaluated. Background Fires that occur in abandoned coal mines, waste banks, and coal outcrops constitute a serious health, safety, and environmental hazard from toxic fumes, deterioration of air quality, and subsidence. Although fires on AML occur in every coal-producing State, the severity of the problem varies, with most underground fires occurring in Kentucky, Pennsylvania, and Wyoming. Surface fires are prevalent in Kentucky, Pennsylvania, and West Virginia. Methods to extinguish or control AML fires, including excavation, fire barriers, and scaling, are generally expensive and have a relatively low probability of success (see figures 1 and 2). Bureau of Mines Study The Bureau compiled information from a variety of sources and found that the problem of AML fires is a serious one. Such fires can involve a high degree of hazard and can be difficult and costly to control. AML fires usually involve smoldering combustion in outcrops, waste banks, or abandoned mines. Given the nature of these fires, it is unlikely that the extent of the problem or the cost of solutions will decrease in the near future.

Jan 1, 1992

By John C. Machisak

THE INJURY data and related employment experience of the coking industry in the United States for 1955 arc presented in this publication under the following general sections: (A) General Injury experience: Tables 1 to 9: Contain current and comparable data on operating statistics, number and classification of injuries, injury-frequency rates, and accident agencies involved in causing injuries. Data are tabulated for the industry as a whole, for each typo of oven: and for the States in which coke is produced.

Jan 1, 1958

Reduce spillage hazards and contamination when adding hydraulic nil to mining machine reservoirs. Approach An easily transported module, that delivers hydraulic oil directly into mining machines, was built and tested. How It Works The Hydraulic Oil Delivery Module is carried, from the oil storage area to the equipment needing oil, in the bucket of a scoop or other utility vehicle. Oil is pumped into the module reservoir from storage, or out of the module reservoir into the machine being serviced, through a long hydraulic hose. During long-term testing, the 115 foot long delivery hose made it possible to replenish the hydraulic oil in mining machines at the face with only limited interruption to the mining operation. (Figure 1 shows one! version of the module.) The compact Hydraulic, Oil Delivery Module consists of: an oil reservoir: a pump driven by a hydraulic motor; two high pressure, low volume oil lines, filters; and a low pressure, larger capacity delivery hose equipped with quick-connect-couplers. The high pressure oil lines are connected to the scoop's hydraulic power takeoff, which supplies the power to pump oil in or out of the module reservoir.

Jan 1, 1977

Permit visual inspection of underground cavities dam the surface. Approach A closed circuit TV camera and a 35mm still camera are lowered down a borehole, and remotely operated. How It Works A platform holding the cameras, and other equipment is lowered on a graduated cable until the depth of interest is reached. Then a quartz lamp and the TV camera are turned on. The television picture is monitored at the surface and recorded on video tape. Areas of special interest are photographed with a 35mm still camera. These photographs contain more detail than TV images because photographic film is capable of higher resolution than a TV transmission.

Jan 1, 1979

Provide an operator cab to assure protection, comfortable use of controls, and good visibility. Approach A cab which raises and lowers by pivoting about d horizontal axis was Installed on two S&S cleanup tractors and tested in two underground working mines. How It Works Hydraulic cylinders actuated by a lever inside the cab cause the cab to pivot about a horizontal axis. This action raises or lowers the cab height. The total cab excursion is 14 inches. A release valve in the hydraulic system allows the cab to lower automatically if struck by a roof load or overhead obstruction. The pivoting action of the cab is engineered so that the operator maintains comfortable use of all controls at all cab heights. The movement is such that the angular relationship of the operator's ankles With the tram and brake foot controls IS consistently within 90 to 100 degrees. Figure 1 outlines the approximate position of the operator at three cab elevations.

Jan 1, 1977

To quickly and reliably assess the stability (safety) of saturated and unsaturated tailings pond embankments. Approach Determine embankment geometry and soil properties, then use that data to obtain the safety factor of the embankment directly from one of a series of factor-of-safety charts.

Jan 1, 1982

By Irven A. Jacobson

The thermal reactions of l-methylindole were studied in the temperature range of 525° to 627° C in a flow reactor. The major products consisted of 2-methylindole, 3-methylindole, indole, quinoline, hydrogen, and methane. 2-Methylindole is formed from 1-methylindole by an irreversible isomerization reaction. The 2-methylindole isomerizes in a reversible manner to 3-methyl-indole, the equilibrium favoring the 3-methyl isomer. Indole is formed directly from 1-methylindole. Quinoline is formed from l-methylindole, 2-methylindole, and 3-methylindole.

Jan 1, 1971