Improving the efficiency of the tailings thickener in a coal preparation plant

A customer had multiple coal types, that were processed through the preparation plant. Some of the coal types had different settling characteristics, which affected tailings thickener efficiency and the “clarometer” instrument that tested settling rates in the incoming feed well failed from time to time, which meant that the floccing rate changed and the suspended solids increased, decreasing the quality of the return water back to the prep plant. Hawk Measurement Systems solved the problem by providing a high powered three-crystal sonar transducer with automatic scum cleaning impact plate.

The two outputs of the sonar system provided:

1. BED Level (Heavy density compacted interface)

2. Hindered/fluffy layer (low density interface)

This heavier ‘BED” level output, was used as one of the input loops, to control the underflow pump, guaranteeing an optimised density being pumped to the tailings dam. The hindered/fluffy layer was used to monitor the deviation distance between it and the heavier compact bed. As the deviation moved greater than a set distance flocculent dosing increased. As the deviation decreased flocculent dosing decreased. 

The high powered three-crystal array transducer, penetrated the suspended solids, even under poor settling conditions. The hindered/fluffy layer output could also be used, in the floc dosing control loop to automate this function if the “clarometer” failed. 

Hawk claims to manufacture the largest range of sonar transducers to provide optimised performance, for all bed level thickener applications e.g concentrate thickeners etc. For more on how to maximise the efficiency and performance of coal preparation plant tailings thickeners http://www.hawk.com.au/files/orca_thickener_control.pdf