OCR

On the flotation floor, four 10-cell banks of new 6o-In. rougher cells were installed and two 10-cell', banks from the original rougher section were diverted to the new section. Thus, the two flotation sections in the expanded mill now each have six 10-cell banks of rougher scavenger cells. Although the original mill circuit had two 10-cell banks of No. cleaners, only one additional 10-cell bank of cleaners was installed for the additional capacity of the new circuit. There is, however, floor space for two additional cells of any type if experience shows they are needed. For lifting in the flotation bay, monorails have been replaced two overhead traveling cranes . Distribution of pulp to the flotation section was originally done through two 4-port distributors. This has now been revised so that two 3-port distributors serve the older flotation section, and one 6-port dis¬tributor serves the new section. Concentrate from all the rougher ceils in the two circuits is collected and distributed to three banks of cleaner cells by a new 3-port pulp distributor. The regrind circuit in the concentrator has been revised by Replacing the 6-in. duplex diaphragm pump from the middlings thickener under flow with a 5 x 5-in. SRL pump. A. larger 5 x 14-ft. ball mill has replaced the original 4x 10-ft. unit, and a fourth 10-in. cyclone has been added to the original bank of three. All tailings from the scavenger flotation cells now go to a 260-ft. diam. traction thickener rather than directly to the tailing pond. The new tailings thickener was installed to recover the additional water required for the expanded mill capacity. Tailing thickener underflow is pumped by a 10 x 8-in. SRL pump to a junction box and then flows by gravity to disposal in the tailings pond. A. new tailings pond is currently being constructed east of the present ones which are virtually filled to gravity capacity. Water collection has been revised with construction of a 56 x 56-ft. concrete sump next to the tailings thickener. This gathering sump collects the middligs thickener overflow, the tailings thickener overflow and the reclaim water from the tailings pond. All of this is pumped to the 250,000 gal. mi steady-head tank located on the hill above the concentrator. Partial automation has been installed in the mill in the grinding, classifying, pH control and tailings disposal sections. At the two rod -mills proportional controls have been added to automatically maintain the flow rate of water to feed so that the rod mill density is kept at 75 percent Pulp density gauges automatically control the cyclone overflow at the ball mills, and a similar gauge controls the density of the underflow fro the middlings thickener to the regrind road section. At the tailings thickener another gauge controls the underflow to tailings disposal by maintaining the solids within a range of 45 to 48 percent.