Mining Publication: Bag and Belt Cleaner Reduces Employee Dust Exposure

A system to reduce occupational dust exposure during bag loading and stacking operations in the metal mining industry was developed. The system, known as the Bag and Belt Cleaner Device (B&BCD), was developed by NIOSH, and designed to clean the surfaces of 50 and 100 pound (lb) bags and conveyor belts while the bags were transported to stacking locations. Cleaning reduces dust exposure for bag stackers, other workers, and the end users of the bagged material. The B&BCD used a combination of stationary and rotating brushes and airjet nozzles to clean material from the bag surfaces and conveyor belt. It was ten feet long and incorporated into the conveyor line. Rotating brushes and compressed air jets cleaned the tops and bottoms of the bags. The stationary brushes plus compressed air jets cleaned the sides. A chain conveyor was used along the total length of the B&BCD which allowed product material removed from the bags to fall into a hopper. Product collected was recycled back into the process using a screw conveyor. The B&BCD was evaluated at two silica sand bagging facilities using 50 and 100lb paper bags. Average respirable dust concentrations measured at one site were reduced from 0.99 to 2.02mg/m3, to 0.63 to 1.89mg/m3. Bag surface vacuuming measurements indicated that vacuum bags gained only 9 to 17 grams (g) per loading and stacking run using B&BCD versus 46 to 171g when it was not used. Measurements made at the second site indicated B&BCD decreased respirable dust exposures by an average of 24%. The authors conclude that B&BCD is effective and practical for cleaning product bags at mineral processing facilities.