Mechanical Dewatering of Tailings Team – SP21

Acknowledgements

Project Advisor: Robin Bullock

Technical Advisor: Mick McCaslin and Dr. Alexandra Wayllace

Donations Made by: Newmont and FLSmidth

Video

Elevator Pitch

As the mining industry is being challenged to construct fewer tailings embankments by replacing conventional tailings storage facilities with dewatered tailings technologies, the goal of this project was to research existing technologies that remove excess moisture from tailings waste and in turn, strengthen their shear capacity. As a whole, this project was focused on technologies that allow for filtering of tailings, thus removing the need for conventional tailings embankments. As the primary goal of this project was to examine and improve upon tailings dewatering systems for large scale mines, the work performed this past year was focused on research and analysis of dewatering technology as well as the design, fabrication, and testing of a functioning bench scale model filter press. This work synthesized a foundation for further technological improvement and innovation within the mechanical dewatering realm as a whole.

Design Approach

Design Solution

The team’s tested prototype was developed and via 3D modelling software called SOLIDWORKS. This allowed the team to design a filter plate set consisting of two outer plates and one middle plate. The two outer plates were designed with the intent of being the pressurized to ~15-20 psi while the center plate would be responsible for drainage. The 3D model was then printed from PLA plastic and sealed using various rubber and acetone-based sealants to ensure a pressure-tight environment. The plate assembly was then fastened together via four threaded steel rods (one in each corner) and ½” pressure fittings were then drilled and tapped into the back of each of the outer filter plates. Filter media from a third-party home brewery kit was utilized between each plate face to act as both the filter media and  gasket material. Once connected to a regulated pressure source, the machine could then be filled with slurry tailings and then ran for a given amount of time to produce filtered tailings cake within the targeted moisture content.

The team ran several trials with several different types of tailings. These included gold, copper, and soda ash mine tailings. It was determined that the developed prototype was successful in dewatering all gold tailings samples tested to a moisture content within the targeted range (~20-25%). The machine did however struggle with dewatering the copper and soda ash tailings tested, achieving moisture contents nearly double the required range. It is suspected that this is due to the extremely fine particle size distribution characteristics of the copper and soda ash tailings. 

Next Steps

Future project scope includes prototype modification and improvement, allowing the machine to become capable of processing more problematic tailings such as the copper and soda ash tailings samples tested. Other avenues of interest include improving the overall efficiency of the developed prototype within the context of throughput capability as well as overall cycle time lengths. These various avenues for further development coupled with further specific sample testing such as proctor compaction and optimum moisture content testing will ultimately continue the progress of the relatively new mechanical dewatering industry as a whole. 

Meet the Team