Thickening is the separation of suspended particles from a liquid by gravity settling and A thickener is a machine that de-waters slurry, separating the liquid from the solids. In fact, most mineral-refining processes go through a solid-liquid separation in a thickener at some point in their processing. As a result, Improvement of the working efficiency of thickening process can have different beneficial outcomes, water utilization during the process, lowering the costs of energy and flocculant and reaching the optimized separation limit.
In order to achieve the highest performance in a thickener, there are many critical key performance indicators and variables – all of which need to be measured accurately and reliably. The thickening process can be monitored and modified by measuring and controlling these key variables, including bed mass inventory, bed level, underflow density and flow, flocculent dosing and overflow clarity.
A good controlling system should be able to stabilize and optimize thickener performance. Higher performance of a thickener can be reached by:
•    Precise control of feed flow
•    Optimization of flocculent dosing
•    Precise measurements of slurry underflow and overflow rates and their correlation
•    Accurate online calculation of solids content
•    Online calculation of bed pressure and height
Accurate measurement of all of these important parameters allows precise thickener process control, which can lead to significant increases in thickener efficiency. These efficiency gains translate directly into overall refining process cost reductions and increased profitability.
As the plant conditions are very dirty, these measurements are not easy and require a lot of attention to select and install the proper equipment. Thus, implementing a suitable approach with appropriate equipment, could be a big challenge in a mineral processing plant.