Guidelines - Flooded bed dust scrubber

1. In event of the scrubber system breaking down, such system will be repaired before further mining is started, unless the method of face ventilation can be changed back to the exhausting system with fan sprays or dust sprays in accordance with the approved ventilation plan. Maintenance will be performed on the scrubbers according to the manufacturers recommendations, or as needed to promote efficient operation. An adequate supply of filters will be maintained.
2. A blowing system of face ventilation will be used with the operating scrubber located on the opposite side of the working place from the line brattice.
3. The minimum and maximum volume of air maintained at the end of the line brattice in the working place may vary according to type and size of the scrubber being used. The minimum of air at the end of the line brattice prior to activating the scrubber will be specified in the plan. The operating range permitted will be 1,000 cfm below to 2,000 cfm above the rated capacity of the scrubber. The rated capacity of the scrubbers shall be compatible to the methane liberation at the face to insure the methane is diluted and rendered harmless. In the event of an unforeseen liberation of methane that necessitates increasing the air velocity at the face that renders the rated capacity of the scrubber inadequate, additional measures shall be taken. These measures could be (1) installation of exhaust canvas in conjunction with the blowing scrubber ventilation system, (2) reduce the depth of cut, and (3) revert back to exhaust ventilation. The minimum quantity of air at the end of the line brattice before starting each cut and the operating range after the scrubber is started will be measured by a certified mine official.
4. The scrubber shall be activated through an electric interlock before the cutting motors are started and shall be operated in conjunction with the operable spray fan system at all times when mining.
5. The line brattice shall be maintained to within 40 feet of the face at all times except when methane liberation requires it to be kept closer.
6. The depth of cut shall be achieved by either full single lifts or multiple alternate lift sequences, depending on mining conditions and methane liberation.
7. The remote methane sensor head attached to the miner shall be installed opposite the blowing canvas lines.
8. The line brattice shall be installed to the last row of roof bolts after mining operations have been completed in each working place, except when methane liberation requires it to be kept closer.
9. Specify the minimum number of head sprays that shall be operated at all times at a minimum operating pressure for those head sprays. No more than one spray may be inoperable in any spray bank. At least two blocking sprays shall be operated at a minimum specified psi. The bar sprays located at the filter screen will be maintained at a specified minimum psi.
10. Maintenance schedule and procedures are as follows:

    Each Cut:

    After the initial (No. 1) half lift is mined 10' wide x ____' long, the filter screen will have the coal particles tapped out.

    After the second (No. 2) half lift is mined 10' wide x ____' long, the filter screen will have the coal particles tapped out and the filter screen washed with water in the opposite direction of the airflow.

11. Maintenance procedures for flooded bed dust scrubbers:

    Each Shift:

    Flush inlets and ductwork with filter in place and filter cover open.

    Back flush slurry pump for 15 seconds by closing hand valve at pump.

    Open sump drain.

    Flush mist eliminator.

    Flush sump.

    Weekly:

    A full traverse air reading will be taken to determine scrubber efficiency. If this reading is less than 90% of the rater capacity of the scrubber, appropriate action will be taken to attain 90% of the rater capacity of the scrubber. A record of this reading shall be maintained.

    Change filter screen out on a weekly basis.

    Monthly:

    Remove demister cell and clean.

12. At the first indication of cut-thru when splitting pillars or during pillar recovery, the scrubber will be deactivated.
13. A drawing(s) depicting nozzle size, flow rate, location, and direction of sprays shall be submitted with the plan. A drawing(s) depicting mining cut sequence shall also be included.