REP47880 - Laserfiche WebLink

Home Browse Search

i~ U 3.0 Effluent Releases and Controls 3.1 Wash Water Circuit • Figure 3.1-1 depicts the water flow through the ore sorter. The recycle tank depicted in figure represents the supply of treated water necessary for the ore washing process in the following manner: Water is drawn from the recycle tank and pumped to two wash screens, and a belt washing circuit. Water from both wash screens is collected at a common point referred to as the scalping screen. Water from the belt washer is collected in a sump below. The overflow from the scalping screen is comprised of +?5 mesh solids and goes to the concentrate pad for transporta- tion to the mill along with ore. The underfloor from the scalping screen is comprised of -25 mesh solids and water, and goes to a common collection point where it is combined with water from the belt washer sump. This water and -25 mesh material is pumped to the thickener. • A flocculant, Nalco 8852, is mixed with treated mine waiver and added to the thickener, to aid in precipitation of suspended particles. The overflow from the thickener is pumped to the recyclE~ tank. The thickener with a volume of 30,700 9a1. is equipped with a rake at the bottom, which inhibits any build-up of solids in the bottom of the thickener. The underfloor, drawn from the bottom of the thickener when solids reach 30-50%, is pumped to a drum filter approxi•• mately 5 times per hour. The filtrate is then returned to the thickener. The filtrate is pumped to the recycle tank; the filter cake (approximately 23% water) then goes to the storage pad for transportation to the mill. Table 3.1-1 shows no trend or build-up is suspended solids in the filtrate during a one-week sampling schedule. Table 3.1-1 Date TSS, mg/1 55-19 83 20 234 . 21 72 22 91 23 290 Treated mine water is added to the recycle tank to make up, as needed, the water volume lost to evaporation.