:: Copper Project to Trial Dry Separation

Water availability is becoming a constraint on copper production in a number of key regions. To address this AMIRA has created P902A to develop a commercially efficient process for the dry separation of copper-bearing material from barren gangue.

Substantial advances have been made in dry separation of other materials most notably coal and some of these processes appear capable of being adapted to treat copper ores. To choose the most suitable target for a development program, AMIRA assessed three known technologies:

• The FGX - 48 dry coal beneficiation process developed by the Tangshan Shenzou Machinery Company: 10 of these systems are already operating in China at rates of around 480 tonnes per hour of coal.
• Australian Inspection Technologies coal sorter. Performance of this has been upgraded from an initial 32 tph of 25-75mm coal to 400-600 tph of 10-25 mm coal.
• CSIRO’s Rotary Classifier, licensed to RCR Tomlinson. A demonstration unit is being assembled which will separate higher density copper-containing material (eg sulphides and composite particles) from lower density, finer liberated silicate gangue.

Currently the CSIRO/RCR Tomlinson technology is the AMIRA team’s preferred option for development. The patented Rotary Classifier uses the natural segregation that occurs in cascading granular material to separate particles in terms of their size and density. It requires no water, is robust, quiet and is not energy intensive.

Copper ores are commonly a mix of silicate gangue materials (such as quartz and feldspars) and copper sulphide materials (chalcopyrite, bornite and tennantite). The silicate gangue materials typically make up 98per cent of the ore by weight and are mostly low density material with a specific gravity in the range 2.6 to 2.9. The copper sulphide materials have a specific gravity greater than 4.0. The gangue particles commonly also have a larger natural grainsize than the copper sulphide materials.

These two factors combined mean that as a classifier rotates, the smaller, heavier copper sulphide material will tend to migrate to the inner region of the bed, creating an effective separation. It is proposed to operate two classifiers in tandem, where the output of one becomes the input of the other and in this way determine how many classifiers are needed to create two streams, one of concentrated copper minerals and the other barren silicate gangue.

P902A proposes that an industry consortium trial the CSIRO Rotary Classifier for copper initially using a simulated copper ore that is representative of the porphyry ores obtained from most large copper mines around the world.

The project was reviewed at the recent Copper Technology Roadmap workshop in Santiago, Chile and will concurrently address ore characterisation of properties that allow such pre-concentration, and ore component differentiation that allow application of the Australian Inspection Technologies ore sorter to copper ores. This ore sorter is a significant advance in technology. Industry support is being invited.