Mining Engineering Commons^™

Equivalent Roughness And Its Application In Calculating Friction Drag Of Mine Roadway, Yan Zhou, Xingshen Wang

U.S. Mine Ventilation Symposium

Some roadways, which do not behave as "wholly rough pipe" as we expected, will have different impact on airflow in a mine ventilation network because of the low Reynolds numbers. For a "non-Wholly-rough" roadway, its resistance factor (R) or the friction factor (¦) is not only dependent upon the relative roughness but also dependent upon the Reynolds number, which varies directly as the flow rate. In this case, R or ¦ is no longer a constant independent of flow rate. Thus, in order to correctly calculate the friction drag of the same roadway for different flow rates, ¦ must be …

Modelling Of The Occurrence Of Hydrogen Sulphide In Coal Seams, A. D. Stewart Gillies, Mehmet S. Kizil, Hsin Wei Wu, Timothy J. M. Harvey

U.S. Mine Ventilation Symposium

Hydrogen Sulphide (H₂S) has been encountered within a number of Bowen Basin collieries, Central Queensland, Australia. High concentration occurrence during mining of a longwall panel raises a number of potential problems, which demand greater understanding to allow efficient mining while maintaining safe and healthy environmental conditions. Longwall panels at Mine A and Mine B have recently mined through H₂S zones. The high H₂S zone mined through at Mine A was wide and covering the whole length of the face comparing to the narrow H₂S zone which was cutting the panel at 45° …

Characteristics Of Airborne Dust In The Return Airways Of The Mechanized Longwall Face, Tevfik Güyagüler, Sinan Keskin

U.S. Mine Ventilation Symposium

In this paper the results of a research study on the characterisation of airborne dust in the return airway of the mechanized longwall face at Middle Anatolian Lignite Mine, OAL are presented. Dust, temperature, moisture and air velocity measurements were carried out in the return airways of the fully mechanized longwalls. Then the analyses of results on real-time concentration data, mass concentration data, effect of moisture, heat and air velocity on dust concentration are made. It has been found that amount of dust in return airway is directly related to the face activities and to the amount of settled dust …

Mitigation Of Methane Emissions From Coal Mine Ventilation Air, Peter Carothers, Milind D. Deo

U.S. Mine Ventilation Symposium

U.S. EPA's coalbed methane outreach program, (CMOP) has prepared a technical assessment of techniques that combust trace amounts of coal mine methane contained in ventilation air. Control of methane emissions from mine ventilation systems has been an elusive goal because of the magnitude of a typical airflow and the very low methane concentrations. One established and cost-effective use feeds the air into a prime mover in lieu of ambient combustion air. This method usually consumes just a fraction of the flow available from each ventilation shaft. The authors evaluated the technical and economic feasibility of two emerging systems that may …

A New Laboratory Technique To Estimate Gas Diffusion Characteristics Of Coal, Satya Harpalani, Shaofan Ouyang

U.S. Mine Ventilation Symposium

This paper describes a new experimental technique developed to measure the diffusion coefficient (D) for a coal-methane system using the transient flow mechanism, and examine its dependency on factors that change with continued flow – pressure and gas concentration. Although developed primarily for coalbed methane reservoirs and coal in the gob regions, it also has application in situations where a second gas is injected in coal since it utilizes the principle of counter-diffusion. The results show that there is a continuous decrease in the value of D with decreasing mean concentration of methane in coal. The logarithm of D varies …

Increased Methane Emissions For Mechanical Miners Working In Burnt Coal, A. P. Cook

U.S. Mine Ventilation Symposium

An intensive research programme has quantified the methane conditions around mechanical miners in production conditions. Methane seam gas contents show an increase of up to 26 times when mining burnt coal compared with normal increase in emission rates. Coal seam methane contents at the face increased from 1 m³/t to 6m³/t in one section, and from 0.1 m³/t to 2.6 m³/t in another. Emission rates from burnt coal were as high as 300 lit/min as it was mined. These increases in content and emission occur immediately after cutting into the burnt coal. …

Flammable Gas Emissions In South African Gold And Platinum Mines Review Of Incidents And Accidents, A. P. Cook, C. F. Meyer, K. Balt

U.S. Mine Ventilation Symposium

Flammable gas emissions are relatively common and widespread across the South African gold and platinum mines, but a general lack of awareness has lead to an increase in flammable gas related accidents and fatalities over the last ten years. The gas is usually a mixture of hydrocarbons C1 to C4 with hydrogen, each in varying quantities, with methane and hydrogen predominant. The three most common causes leading to gas accidents are changes to the ventilation, lack of testing for gas, and contraband, with gas ignitions caused by contraband and illegal tampering with caplamps. Development work accounts for 70 percent of …

Design Of Methane Drainage Systems To Reduce Mine Ventilation Requirements, Michael D. Zuber, Charles M. Boyer Ii, Denise L. Delozier

U.S. Mine Ventilation Symposium

There are numerous proven methods to drain methane from coal seams in coal mines. These systems include vertical wells drilled ahead of mining, horizontal boreholes, gob wells, and others. However, these drainage systems are not typically applied properly to optimize gas recovery and minimize the cost of ventilation to the mine. This lack of optimization generally occurs due to the large up-front costs associated with the drainage systems and the lack of knowledge regarding the drainage technology. This results in the mine having a "reactive" response to methane drainage issues as opposed to a "pro-active" plan for handling methane drainage. …

Methane Ignitions On Roof Bolters In Underground Coal Mines, John E. Urosek, William J. Francart

U.S. Mine Ventilation Symposium

Although not as frequent in nature as ignitions on continuous miner or longwall faces, ignitions of methane on roof bolters have caused serious injuries to underground coal miners. After reviewing the accident reports for all roof bolter ignitions from 1981 to 1998, a summary of the forty-one accidents has been developed. Of interest in the database is the ignition source, method of face ventilation, local velocity, methane liberation, size of the methane body ignited, and the duration of the flame. Three example ignitions are included.

Comparison Of Methane Concentrations At A Simulated Coal Mine Face During Bolting, Charles D. Taylor, Edward D. Thimons, Jeanne A. Zimmer

U.S. Mine Ventilation Symposium

Strategies for monitoring methane levels during roof bolting in an extended cut entry were evaluated. Testing was conducted at the Pittsburgh Research Laboratory's methane test gallery. Operating conditions were varied and methane releases at the face and drill holes were simulated. Methane readings were taken at the face, and at locations outby the face. Results show that, when the major source of methane was at the drill holes, the highest methane readings were at locations on or 6.1 m (20 ft) inby the bolting machine. Methods for selecting better outby sampling locations, when the majority of the methane is released …

A Proposed New Method To Determine The Effectiveness Of In-Heading Methane Control, F. J. Van Zyl

U.S. Mine Ventilation Symposium

Various methods have been derived to determine the effectiveness with which ventilation systems clears headings of methane in a bord-and-pillar sections. A problem with applying these methods in underground sections is that the either require the face-area air quantity to be measured, which is virtually impossible in South African collieries, or they were developed for test galleries, making it difficult to use in production sections. Taking this into consideration the methane safety index (MSI) method was developed. The method utilizes methane data recorded around an active continuous miner (CM) and an activity log of cm operations to quantitatively assess methane …

Evaluation Of A Continuous Miner Half-Curtain Dust Control System In A South African Underground Coal Mine, Bharath K. Belle, J. J. L. Du Plessis

U.S. Mine Ventilation Symposium

The issues of public health and safety in the mining industry have been dealt with around the world through the intervention of governments. In 1997 the South African Department of Minerals and Energy (DME) sent out a directive to reduce the dust concentration level to /m³ at the operator's position for the sampling period. The reasons for the difficulty with compliance are: long headings up to 35m, inherently high dust generation rates of coal, and the increased use of highly mechanized equipment. A project was formulated under SIMRAC auspices with the title of "Underground Mechanical Miner Environmental Control" to …

Methods For Dust Removal In Roadway Sections, Walenty Frydel, Marcin Steindor, Robert A. Jankowski

U.S. Mine Ventilation Symposium

Systems for dust extraction in roadway workings subjected to suction or forced ventilation are a combination of dust collecting equipment and facilities designed for ventilating the working. Such a combination of suitable equipment provides safe and effective dust removal and ventilation of a roadway working as well as is determinant of proper cooperation of the equipment a system is composed of. The development of effective dust collectors of wet type which provide safe operation under conditions of great exposure to coal dust and methane explosion hazards as well as of vortex ventubes allowing methane accumulations under the roof to be …

The Effects Of Offshore Mining Of Beach Quality Sediments On Nearshore Wave Climate, Frank R. Lonza

Civil & Environmental Engineering Theses & Dissertations

Coastal communities rely on the beaches to attract tourism, but these sources of revenue require maintenance, such as beach nourishment. In an effort to maintain these beaches without causing any detrimental results, research is conducted to determine what effects, if any, exist when mining for sand in offshore areas.

The U.S. Government is permitting the search for beach quality sands offshore but is also ensuring that such mining will not have adverse results to the nearshore wave climate. This study was conducted using a coarse grid bathymetric map to calibrate a numerical model developed by the Danish Hydraulic Institute (DHI). …

Comparison Of Toms And Avhrr Volcanic Ash Retrievals From The August 1992 Eruption Of Mt. Spurr, N. A. Krotkov, O. Torres, C. Seftor, A. J. Krueger, A. Kostinski, William I. Rose, Gregg J. Bluth, D. Schneider, S. J. Schaefer

Department of Geological and Mining Engineering and Sciences Publications

On August 19, 1992, the Advanced Very High Resolution Radiometer (AVHRR) onboard NOAA-12 and NASA's Total Ozone Mapping Spectrometer (TOMS) onboard the Nimbus-7 satellite simultaneously detected and mapped the ash cloud from the eruption of Mt. Spurr, Alaska. The spatial extent and geometry of the cloud derived from the two datasets are in good agreement and both AVHRR split window IR (11–12µm brightness temperature difference) and the TOMS UV Aerosol Index (0.34–0.38µm ultraviolet backscattering and absorption) methods give the same range of total cloud ash mass. Redundant methods for determination of ash masses in drifting volcanic clouds offer many advantages …

Early Evolution Of A Stratospheric Volcanic Eruption Cloud As Observed With Toms And Avhrr, David J. Schneider, William I. Rose, Larry R. Coke, Gregg J. Bluth, Ian E. Sprod, Arlin J. Krueger

Department of Geological and Mining Engineering and Sciences Publications

This paper is a detailed study of remote sensing data from the total ozone mapping spectrometer (TOMS) and the advanced very high resolution radiometer (AVHRR) satellite detectors, of the 1982 eruption of El Chichón, Mexico. The volcanic cloud/atmosphere interactions in the first four days of this eruption were investigated by combining ultraviolet retrievals to estimate the mass of sulfur dioxide in the volcanic cloud [Krueger et al., 1995] with thermal infrared retrievals of the size, optical depth, and mass of fine-grained (1–10 μm radius) volcanic ash [Wen and Rose, 1994]. Our study provides the first direct evidence of gravitational separation …