2009 – Water In Mining, AusIMM Conference, Perth WA
There are no large rivers in Western Australia capable of supplying water for
processing magnetite ores. If sea water is used there are severe corrosion issues and
the requirement to wash the concentrates with potable water. If groundwater is used
there is a need to treat the water and sustainability is an issue for large projects
because of potential drawdown of the aquifer.
If sea water is desalinated the cost of the water is high because of the power
requirement. At the same time the necessity to conserve water has lead to flowsheets
where all of the tailings have to be filtered to minimise the water requirement.
Managing the various water qualities and optimising water recovery and quality has
resulted in optimising the water balance and issues meeting environmental obligations.
Reverse flotation is a critical final step in reducing the silica level in the
final concentrate and requires good quality water.