Dewatering Upgrades Can Improve Phosphate Tailings Filtration

Hi-Rate Thickener

Published by Fertilizer International Magazine

Optimization of beneficiation plants can eventually create a bottleneck at the plant’s filters. The modernization of the filter to handle the process increase can be very costly. A very common flowsheet will use a thickener upstream of the filter. Improvements in the upstream thickener translate to significant benefits to the downstream filter and help with plant optimization. The goal is to increase the water recovery at the thickener to reduce the hydraulic load on the filter. This approach can be very beneficial for difficult streams to filter with fine particle size distribution. Phosphate tailings is a prime example.

In this article, WesTech engineers Jerold Johnson and Brad Bentley outlined important ways to evaluate the thickener upstream of the filter and reduce the plant bottleneck in the overall operation.

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They suggested that optimizing the thickener is a cost-effective way to improve the bottleneck at the filter. The article references thickener upgrades such as improving thickener control. Control is dependent on consistent accurate bed level measurements. The WesTech patented bed level sensor MudMax™ is introduced, providing the technology needed for control. Also, the article introduces the EvenFlo® to address common feedwell issues. The EvenFlo can improve overflow clarity, reduce dosage, improve operating costs, and increase the weight percent solids in the underflow.

Modernization with this technology will achieve the goal of recovering more water at the thickener. There is also the potential to replace the high-rate thickener with a high-density thickener. These thickeners generally produce +10 percentage points higher underflow density and drastically reduce the water fed to the filter. These modernization techniques apply not only to current plants but to greenfield plants as well.

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