An innovative twist to a common piece of industrial equipment could give companies a valuable tool to better treat oil sands tailings. Filter press technology uses applied pressure to separate solids from liquids by squeezing the feed slurry between plates to quickly remove the water. This technology is routinely used in other mining industries and now, for the first time, it has proved to be effective in removing water from oil sand tailings, which is a mix of water, clay, silt and bitumen that is left over from mineable oil sands bitumen extraction.
The filtration technology has potential for fluid tailings treatment because it cuts the time required to convert tailings into a suitable reclamation material – from many years to just a couple of hours. The end product is a dense filter cake that can be easily transported by conveyer or truck to a land reclamation site.
Longer term benefits include the potential to reduce the size of tailings ponds, as well as the need for additional water for operations. The water which was contained in the tailings slurry is recovered and can be recycled for use in the bitumen extraction process.
By using a combination of chemical additives, the ability to efficiently filter these tailings was demonstrated in a series of small scale experiments and pilot plants. An initial laboratory study and small pilot plant proved successful enough to move to a commercial scale pilot plant and, in 2019, a purpose-built facility was constructed at Canadian Natural’s Muskeg River Mine. This pilot contained two filter presses each with one hundred 2m x 2m filter frames. These large presses would treat approximately 15 tonnes of solids per batch.
The large- scale filter presses performed well, removing up to 75 per cent of the water and producing a dewatered product which could then be managed with typical earth moving equipment in a deposit area.
By the time the successful two-month trial wrapped up, the team had established that commercial filter press technology was viable in oil sands mining operations and prepared enough material to study its behaviour in a landfill-type deposit. While a thorough economic assessment still needs to be carried out following the precedent of other mining sectors is definitely beneficial, as large filter presses are already being used and are on the market today.