Combimix proves itself in Canada’s ‘Valley of the Kings’

May 2017

Reference at a glance


Design and supply of a reliable mixer for the special climatic and logistical challenges of a Canadian gold mine


Combimix mixer with "overflow" process and double mixing unit

Operating site

British Columbia, Canada




Conditioning of tailings during gold extraction


Innovative mixing technology for backfilling with reduced energy requirements

The Brucejack Gold Mine in the province of British Columbia, Canada commenced operation in the summer of 2017. It uses a Combimix mixer supplied by BHS-Sonthofen to stabilize the tailings – fine-grained residues from gold mining used for backfilling the mine. Among other things, the mixer sets itself apart with especially high availability at the remote location on Brucejack Lake.

The Brucejack Gold Mine operated by Pretium Resources, Inc. extracts about 2,700 tons of gold ore per day. Nearly the same amount of residue is produced by the processing plant’s belt filter. Used to backfill the mines, these tailings first have to be stabilized with cement and water. That is why the mine operator opted for a Combimix mixer from BHS – which combines the mixing technology of the twin-shaft batch mixer and single-shaft continuous mixer.

The Combimix mixer applies the overflow process: The material to be mixed is added at one end of the mixing trough and leaves the machine through an opening on the opposite end – a proven solution for fine material that does not settle on the bottom of the mixer due to its density. For the ‘Brucejack’ project, BHS also equipped the mixer with a dual mixer mechanism that thoroughly breaks up, disperses and homogenizes the filter cake, even at low rotational speeds. Considerably lower energy consumption compared to other mixer types is a welcome side effect of the lower rotational speed. The average retention time of the material to be mixed in the trough is about 1.5 to 2.5 minutes. It is regulated through the controlled addition of new material at the inlet. To maximize the length of maintenance intervals and minimize downtime, BHS equipped the mixing trough with 28-mm thick and especially wear-resistant Optilong tiles. Fully automated lubrication is integrated for the same reason. It reaches all lubrication points (more than a dozen) and works according to a flexible, adjustable schedule. Another special design feature of the BHS mixers further contributes to the mixer’s high availability: The mixer shaft bearings are physically separated from the seal to the mixing trough, thus ensuring that the material to be mixed is kept clear of the bearings. A high-pressure cleaning system was also installed for the first time for this type of application.