Scrubber In Blowing Section Offers Good Ventilation Taking 50 Foot Cuts - Objective

Maintain good blowing face ventilation while taking deeper cuts with a radio-remote, scrubber-equipped miner. Approach A six week in-mine study of face ventilation effectiveness was made by comparing the existing MSHA-approved blowing curtain setback distance of 25 ft with brattice set back distances of up to 50 ft. Effectiveness was determined by measuring methane levels at the face and in the immediate return. How It Works Blowing ventilation systems are commonly used in mines because the high velocity air stream created by these systems rapidly mixes with and dissipates methane generated during the cutting of coal. A drawback to blowing ventilation is that the work area is placed in return air and this may create dust compliance problems for the shuttle car and mining machine operator. To clean dust from the return a number of mining machine manufacturers supply dust scrubbers built into the machine. Dust-laden air is drawn into ducting at the front of the mining machine's boom and is ducted to a scrubbing unit located on the machine's main frame. The clean air from the scrubber is discharged as a high velocity jet toward the return, generally from the left fender of the mining machine. When taking cuts deeper than 20 to 25 ft with a scrubber-equipped machine, the machine's discharge is in by the mouth of the blowing curtain, creating a concern by mine workers that a loss of air to the face could result. However, Bureau of Mines research found that the push or throw of air toward the return by the scrubber discharge jet allows good face ventilation to be maintained with extended curtain setbacks.