Laserfiche WebLink
,• <br />i <br />in front of the spigots is used to raise the tailings dam in 1 or 2 foot increments. <br />If the desired gradation, permeability, and compaction characteristics of the <br />tailings cannot be obtained by using spigots, a cyclone is employed to control <br />the sand separation process. A 2.8 to 1 horizontal to vertical elope gradient <br />waa maintained during the conatructien of the tailings dam, which was raised <br />in successive stages to a maximum height of 30 feet. When the tailings im- <br />at its <br />• <br />• <br />• <br />• <br />This milling complex was designed to maintain a stable water~balance <br />throughout the ore processing and tailings impoundment system. 'Ihe milling <br />operation requires 4 tone of water for every ton of ore pnxeseed in the gravity <br />and flotation concentration circuits. Fresh water is introduced into the milling <br />process in the grinding circuit (see Figure 1). Moat of the water that is used in <br />grinding and classification, and in the gravity concentration circuit, is recycled <br />from the thickener tank overflow launder back to the ball mill. Fresh water ie <br />also added to the thickened pulp as it passes from the thickener tank underflow <br />to the flotation concentration circuit. A closed circuit was planned to recycle <br />the water that accompanies the tailings pumped from the mill to the tailings <br />retention structure. 'Ihe excess water that accumulates in the tailings pond is <br />decanted from the water pool and stored underground in the Hazel A. edit. A <br />steel pipe with water decant holes is used to remove the excess water that <br />collects in the tailings pond. This decantation line is used to control the water <br />level in the tailings pond, and to keep the water pool as far as possible from the <br />crest of the embankment. Additional sections of steel pipe were connected to <br />the decantation line to regulate the elevation of the water pond as the tailings <br />dam's height increased. Several seep rings were attached to the steel pipe to <br />prevent the tailings from piping along the decantation line. The decantation <br />line was connected with the.HaaPl-A A~1~+ + rouehone of the teat holes that <br />Bureau of Mines. This <br /> <br />to <br />The amount of water that is decanted and stored underground in the Hazel A. <br />Adit is primarily determined by the water balance maintained throughout the <br />~ processing and impoundment system. The water consumed in the milling pm- <br />cess and lost in evaporation from the tailings pond does not exceed 20 percent <br />of the water used in the mill. The water consumed in the one milling process <br />mainly results from water entrapped in the gravity and flotation concentrates <br />and in the unconsolidated tailings. Because of the altitude and limited size of <br />the tailings pond, only a relatively small amount of water was lost due to evap- <br />~ oration. Recycling the mill water reduces the amount of fresh water needed in <br />the milling proceaa, aad decreases the quantity of water pumped from heft <br />Hand Creek. <br />Because of the hillside location selected for the tailings impoundment atruc- <br />~ tore, water runoff inflow has not been substantial. A drainage diversion ditch <br />~~- °'~" <br />~~~ <br />h <br />-~- ~ <br /> <br />