GRINDING SECTION

High-angle view of grinding bay in millThe grinding section consisted of two rod mills, each 10 ft. by 16 ft., and three pebble mills, each 12 ft.-6 in. by 18 ft. Each mill was driven through an air clutch by a 1000 h.p. 4000 volt synchronous motor.

All the units were supplied by Dominion Engineering Works of Montreal. Provision was made for the installation of another pebble mill when capacity was expanded to 9000 tons per day. Liners were chrome-moly and manganese steel supplied by Esco Limited.

This section took up one 68-ft. bay across the full 240- ft. width of the concentrator building. Equipment layout was based on two independent grinding lines. Each rod mill operated in open circuit feeding into the pebble mills which were operating in closed circuit with the classifying cyclones. Recirculating load was set at 400%. Processing a feed consisting of 8% pebbles, 4-in. by 2-in., and 92% rod-mill discharge, minus 6-in. mesh, the pebble mills will yield a flotation feed of 5% plus 65 mesh, and 64% minus 200 mesh.

Again, in the grinding section, one was struck by the high degree of control instrumentation.