Quarry

Sludge dewatering and water recovery from sand and aggregate washing processes

Bilfinger Water Technologies designs and builds complete water recovery and slurry dewatering systems for sand and aggregate washing plants. These high-performance systems minimize water usage and solid disposal problems.

The water recovery and sludge dewatering plants supplied by Bilfinger Water Technologies are generally made up of the following stages:

1. The sludge well receives the slurry to be treated from the washing plant. It is equipped with a lifting pump.
2. The flocculant dosage station dilutes and adjusts, automatically, the dosage of the flocculant necessary to accelerate the process of solid-liquid separation.
3. The clarifier allows the separation of the water (overflow), which can be used again, and the solids (underflow), which are discharged as a concentrated slurry.
4. The clear waters storage tank holds the recovered clean water before being returned to the washing plant.
5. The sludge storage tank receives the concentrated slurry from the underflow of the clarifier and serves as an accumulation and feed tank for the sludge dewatering stage. This stage is recommended to allow the filter press to be fed a consistent slurry at a rate independent of the clarifier underflow supply.
6. The sludge dewatering process is usually carried out with a plate filter press which has the following advantages:

• high dewatering performances;
• eliminates environmental and safety problems associated with tailings dams;
• offers high water quality and maximum recovery of washing water;
• delivery of very compact and dry filter cake which can be used as a stable filling material in the building industry.