Lessons learned from thickening and filtering tailings for dry stacking

Abstract

The metallurgical testwork for a new gold project indicated acceptable settling rates and filtration rates. The equipment was sized, and the plant constructed. Subsequently, commissioning of the thickening and filtration for dry stacking of tailings indicated serious deficiencies with the design and a much lower achievable throughput. The throughput was some 30% of design and cash flow considerations were that the project throughput was restricted by poor performance of the thickeners and tailings filtration acting as a bottleneck. Mineral Engineering Technical Services Pty Ltd was commissioned with the task of increasing filtration throughput and removing the bottleneck. For the thickeners, new flocculants were evaluated, changes to the flocculant dilution were made, and thickener underflow pump speeds were increased. An additional filter feed storage tank was installed to allow for short-term filter shutdowns. With the two belt filters, various flocculants, guar and diatomaceous earth were evaluated. Also, more permeable filter cloths were evaluated in order to increase filtration rates. The single biggest improvement achieved was with the use of coagulants. This paper describes how the task was managed and what steps were taken to achieve design throughput.