2012 – SME Annual Meeting 2012, Seattle USA

Abstract:

Water for mineral processing is in short supply. Water is a precious resource in Western
Australia because there are few large rivers available and groundwater has sustainability
issues associated with it. Desalination is increasingly used but environmental concerns have
been raised regarding the waste stream impact on the marine environment. The resource
sector is growing at such a rate that new water resources will become critical and the subject
of competing interests.

The history, quality and quantity, sustainability, issues and approaches, water use, balances
and audits, the challenges ahead and environmental considerations are considered in relation
to water in mineral processing. The presence of inorganic salts either naturally occurring or
dissolved from the ore (gypsum, magnesia) has an effect on mineral processing unit
operations.

Technologies such as filtering, sedimentation, clarification and microfiltration are considered.

The need to characterise the water (i.e. the alakalinity, TDS, pH, hardness, full elemental
analysis and organic content of the water being used) is discussed. The impacts of poor
quality process water, such as saline waters include precipitation of calcium carbonate or
sulphate or iron hydroxide resulting in reduced floatability and inadvertent activation of
gangue minerals resulting in loss of selectivity. Common foulants include scale, biofouling
and suspended solids. Antiscalants are widely and successfully used under such
circumstances.

For sustainable mineral processing water audits are necessary based on actual water balances.
This will highlight balancing water quality and optimise the use of recycling. The
requirements for iron ore processing are far more stringent in comparison with other
commodities such as gold ore processing. A number of case studies are used as examples.

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