Our Newcastle office has recently been appointed to assist with the replacement of two semi-autogenous grinding (SAG) mills and the upgrade of the motor and electrical drive systems at a copper mine in New South Wales.

Engenium, now Stantec will provide the detailed design and drafting services for the concrete remediation works, foundations upgrade, new switchroom and access stair footings, as well as site construction and engineering support to prepare the scope of works, material take off sheets, and quality inspection and test documentation for civil construction on site.

The engineering design was previously completed to feasibility level, identifying some issues with the existing mills foundations which are now around 55 years old. In addition, the feasibility phase work did not account for variable speed mill operation and the impact of natural frequency of the mill foundation falling within the proposed operating speed range. The foundations were also identified as being less than the total mass recommended by the mill components supplier.

The grinding circuit at the copper mine consists of two primary cascading SAG mills, which are operated on either a closed or open circuit depending on the feed grade, and a third ball mill that operates in closed circuit with cyclones as a secondary to the primary circuit.