Newcrest Cadia Valley Operations (CVO) is located 25 km south west of Orange and comprises the Cadia Hill open Pit Mine and the Ridgeway Underground mine and a shared ore treatment facility. Production in 2004/05 was 690,000ozs of gold and 72,000 tonnes of copper. Without a reliable supply of water the operations would not be viable.
Water use at Cadia
The main use of water at CVO is in the processing of the ore. After grinding the fine ore undergoes a process called flotation to recover the copper and gold. The ground ore is mixed with water and a frothing agent. It is then agitated and injected with air to generate bubbles. A collector is then added to the mixture. The collector attracts and coats the sulphide material hosting the precious metals and at the same time it has an aquaphobic property, which means it seeks the quickest route away from the water. As a result the collector attaches to the bubbles as they rise through the mixture and takes the copper and gold with it. This process forms a froth rich in precious metals which is recovered and forms the copper gold concentrate produced by CVO.
The non-mineralised slurry, called tailings, is then thickened to reduce its moisture content and sent out to the tailings storage facility. Water from the tailings storage facility is recycled to the plant, however the main water loss is through evaporation. Water is constantly being added to the process.
Water Sources at CVO
This 'make-up' water is sourced from the following, in order of priority:
Water and the Environment at CVO
CVO has a number of programs in place to ensure that its operations have minimal impact on water quality and quantity for downstream users and the environment. A comprehensive environmental monitoring program is in place to monitor both water quality and quantity and includes both surface water and groundwater. Surface water flows are monitored in a number of creeks surrounding the operations. Part of the development consent was that CVO maintains a minimum flow in Cadiangullong Creek to satisfy downstream users and environmental requirements.
In order to restore riparian environments to a more natural condition CVO is undertaking a willow removal program along Cadiangullong Creek which involves poisoning the willows, removing the dead timber, then replanting with local creek species and excluding stock from direct access to the creek.