In July 2004 a flotation concentrate regrind circuit was commissioned in the
High Grade' Ridgeway concentrator at Newcrest's Cadia Valley Operations. This
was the culmination of two years of project testing, process design and planning
which commenced shortly after commissioning the concentrator in March 2002.
During the two-year project evolution alternative grinding technologies were
evaluated from conventional ball milling through to sand milling.
A Detritor mill was eventually selected for the duty and the criteria on
which this selection was based will be presented. As the project evolved so too
did the equipment sizing with the concentrator quickly exceeding design capacity
of 4 Mtpa and currently averaging 5.6 Mtpa, the process design had to
accommodate this and future potential throughput increases. This paper will
focus on the supporting testwork, circuit surveys and concentrate properties
which were used as the design basis for the project. The economic evaluation
which led to the project receiving board approval in November 2003 will also be
presented. Detailed design and construction management issues will be discussed
as will preliminary results and findings up to November
2004.