Screw press technology is an innovative approach to tackling the growing pressure to conserve water and minimise the environmental impact of mineral tailings disposal. The principles of the technology have been known for a considerable period of time in non-mining applications such as water treatment, wastewater (municipal sludge), as well as in the paper and chemical industries for dewatering solids, particularly those containing clays.
The screw press represents a viable niche technology for filtering fine and high-clay tailings, without the prior thickening stage, and is capable of producing a filtered product that is sufficiently consolidated and dry enough to provide a product suitable for conveying and dry stacking.
Ishigaki screw press was introduced in 1990 and key features are:
- continuous operation and excellent availability
- low wear to plant
- acceptable flocculant consumption
- low carbon footprint and low noise levels
- fully automatic.
These features lead to simpler plant layouts, easier maintenance, smaller spares inventories, reduced wear, smaller footprint and overall lower capital and operating costs.
The amenability of a particular tailing stream to treatment by screw press technology may be determined by test work. Two pilot plant studies are described where this technology has been applied in the mineral industry being flotation tailings from a rare earth (RE) mineral concentrator and coal tailings. In addition, preliminary details are given of an ACARP sponsored research program titled ‘The application of screw press filtration in tailings dewatering’.
Absolon, V J and Nieuwkerk, D,
2014. Innovative use of screw press filtration in tailings dewatering plant
design, in Proceedings 12th AusIMM Mill Operators’ Conference 2014, pp
449–456 (The Australasian Institute of Mining and Metallurgy: Melbourne).