Feedwell is the heart of a thickener

Abstract

Thickeners that produce non-Newtonian underflow suspensions use the same feedwells as with other thickener types. The functions of converting the horizontal momentum of the feed to a vertical flow and the promoting flocculation of the suspended solids are the same for any thickener. The industry has correctly addressed the feedwell design in recent years. The effectiveness of the feedwell design to accomplish these functions has generally been poor in the industry. Short circuiting flows carry the solids into the thickener prematurely before all the suspended solids have been captured. Also these flows generate such force that solids are carried to the overflow launder before settling can occur. Paste thickeners are oftentimes used as the final dewatering stage of the tailings and the main source for process water return. Clarity of the process water is often regulated if discharged and poor clarity recirculates solids that cause a burden on the system. The patented Evenflo TM feedwell has been installed in all types of thickener in China and around the world with significant improvements to overflow clarity and overall thickener operation. This paper provides case study results of clarity and elimination of short circuiting.

Paste thickener benefits for soda ash: liquor recovery, mine backfill and surface stack

“…Another recent improvement in the thickener has focused on the feedwell design. The benefits and description of the WesTech patented EvenFlo TM feedwell were presented in Johnson and Accioly (2017). The design uses a two-stage feedwell that receives the feed flow in an inner raceway that directs the feed stream radially out into the feedwell.…”