Filtered(treated) water delivered to hot strip mill for roll cooling and descaling, so the waste water contains scale, oil grease and dust. The recirculation rate of waste water is 7500 cubic meter per hour.
Waste(used) water sprayed into collection flume and flow into scale pit, where 80% of scale
and heavy dust deposited to the bottom, and light oil grease buoied up to the surface owing
to the difference of specific gravity. The deposited scale is cleaned by bucket crane to
drying pit, and the buoied oil grease is loaded into waste tanks by floating pumps.
Thereafter, after scale pit, the waste water which included less than 60ppm of suspended
solid and 10ppm of oil grease will be conducted into waste water treatment plant. Poly-
coagulant is to be added into waste water and well stirred depending on flow rate. Suspended
solid was coagulated and deposited to sedimentation basin bottom. Conducted coagulum from
sedimentation basin bottom is sent to dehydrator and squeeze out to slurry cake, and then
sent out. Before water conducting from sedimentation,scum separator will skin off buoyancy on
water surface. Then, water flow into high rate filter and the remaining suspended solid is
filtered out to less than 20 ppm. At last, the filtered water was dilivered to cooling tower
to descend water temperature to less than 35 ¢J and recirculated to HSM again.
Waste Water Treat Plant (1)
Waste Water Treat Plant (2)