Managing Our Most Precious Resource-Quality and Quantity Issues with Water for Mineral Processing in Western Australia

摘要

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 floatabiliry 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.