Despite low nickel prices during the 2008-2009 global financial crisis and unexpected sea freight delays, Outotec and Cosmos worked closely together during the filter project to overcome these obstacles.The end result was the commissioning of a large, modern pressure filter at Cosmos with 28% more capacity than the old one and within a 9-month timeframe that coincided with Cosmos’s mill optimisation.
With its dewatering constraints solved by a freshly painted, refurbished and modernized Outotec Larox pressure filter, Cosmos is ready to produce new benchmark dewatering rates. These improved rates will meet Xstrata Nickel Australasia’s (XNA’s) production target of 13k nickel tonnes per annum (Ni t pa) for 2010, a significant increase from 7.5k Ni t pa in 2009.
Cosmos is a remote nickel-sulphide operation situated about 900 km north-west of Perth in Western Australia. The mine produces high-grade nickel concentrate containing 18-22% nickel that is trucked south to Esperance Port and shipped to Xstrata Nickel’s Sudbury smelter in Canada.
Throughout 2009, Cosmos systematically upgraded and optimised its processing plant in preparation for XNA’s doubled 2010 production target. The plant’s debottlenecking process included a review of a 17-year old Larox pressure filter, inherited with the Cosmos site when XNA bought out Jubilee Mines in February 2008.
The Cosmos filter review identified that the Outotec Larox pressure filter model PF 25/32 (25 m2) was working to full capacity for its configuration and that its small size would become a constraining factor in meeting XNA’s higher production production rate. Service technicians from the Outotec Perth office were sought for a filter audit, as well as a quote for upgrading and modernizing the existing equipment to a 32/32 capacity.
Outotec’s filter assessment found that the structural components were badly corroded after extensive outdoor weathering. Outotec deemed the filter’s life to be very limited and that an upgrade and modernization of its mechanical parts were not in Cosmos’s best interest long term.
Concurrently planned with debottlenecking the dewatering constraints, Cosmos’s mill optimization was scheduled for completion within nine months. This timing, however, didn’t allow for a longer delivery time that was required for a brand new filter replacement. In response, Outotec searched worldwide for an available, suitable, second-hand pressure filter.
Providentially, a hydraulic Outotec Larox pressure filter model PF 32/38 (32 m 2 ) was sitting unused in England, leftover from a previous starch and chemical operation. It was perfect for Cosmos’s needs. Further expandable to a maximum capacity of 24 plates (38 m 2 ) (i.e. a PF 38/38 size), the available second-hand filter could also be easily converted to an abrasive minerals slurry application.
During the filter’s shipping to Finland, its refurbishment and modernization and then it's further shipping to Perth, Outotec kept Cosmos continually up-to-date with the filter’s progress. As a result, when unexpected logistics delays occurred during the filter’s shipping travels, Cosmos was able to readily accommodate these reports into the filter’s installation schedule.
The refurbishment and modernization of this second-hand filter also produced an ecological benefit by reducing the unnecessary carbon footprint of new filter manufacture through the use of an existing one.