Water is used for removing scales from Hot steel strips. This water needs to be treated to remove sludge (scale-like material - Ferrous oxide) and oil. The current method of water treatment is not able to remove all the scale/sludge even in 24 hours.
In the current process, the water (Total suspended solids around 11-13 ppm) is first discharged using flumes (by gravity) into a large tank (22 meters in depth) called ‘Scale-Pit’ (Figure 1). Oil is skimmed out from the top. Simultaneously the solid waste which settles at the bottom of the scale pit is removed using jaw-like grab buckets. This does not ensure 100% removal of sludge as it sticks to the bottom of the pit.
The water is then pumped to the settlement tank where the oil and grease are again skimmed out, and solid waste remnants settle down further. The water is then pumped into High-rate filters, which employ rock, slag & synthetic materials such as plastic modules as filter media. The outlet from High-rate filters is sent to Cooling Towers and then reused.
Muck that settles down at the bottom in both scale-pit and settlement tanks is hard to remove. Thus, we are inviting solutions that can either,