This paper describes a novel water spray system, consisting of flat fan spray nozzles, mounted across the top of the mining machine, along with high flow, flat fan, and higher pressure hollow cone nozzles mounted under the boom. The anti-rollback underboom spray system minimizes dust rollback while increasing dust knockdown by its unique positioning of spray manifolds and orientation of spray nozzles. Respirable dust suppression characteristics of the system acted in three ways: (1) by wetting the surface of the broken coal material to prevent dust from becoming airborne, (2) by controlling the airflow pattern at and near the face to minimize dust rollback to the operator's control location, and (3) by dust knockdown, i.e., airborne capture, or scrubbing of airborne dust from the air. During underground trials, the anti-rollback underboom spray system reduced dust levels at the operator's position and in the immediate return by 55 and 15 pct, respectively, when compared to a conventional spray system. Quartz dust levels at the operator's position were essentially eliminated, while quartz dust levels in the immediate return were reduced by 57 pct. Applying the concepts of this technique throughout the mining industry should reduce the health hazard associated with excessive exposure to respirable quartz dust, as well as allow coal mine operators to comply with the associated, more stringent, respirable dust standards.
Ch. 84, Proc. 3rd U.S. Mine Ventilation Symp., 1987, PP. 605-611