One of the largest alumina refineries in Australia needed to replace an ageing ball mill critical to its operation, with Xtreme Engineering, a heavy fabrication company, partnering with Mammoet to provide a solution for the exchange and replacement of the old and new equipment.

The mill was located in the centre of the plant, making access challenging due to narrow clearances and thus the replacement operation required comprehensive engineering.

Recognising the complexity of the task, the importance of the refinery’s continuous operations and team safety, Mammoet used its engineering expertise and advanced technological capabilities to develop a bespoke solution aimed to facilitate a seamless exchange of the mill, all while minimising disruptions within the live plant, it said.

By employing its proprietary Move3D engineering software in combination with traditional 2D drawings, Mammoet engineers meticulously planned every aspect of the operation, taking into account the mill’s challenging location with tight clearances and limited accessibility.

Given the spatial limitations within the work areas, the use of hydraulic cranes or gantries was not viable. Recognising this challenge, Mammoet developed a solution that entailed the use of a ‘jack and pack’ system. With no as-built drawings available, Mammoet used a point cloud scan, provided by the customer, to generate an accurate representation of the plant in its current state within Move3D, facilitating a comprehensive visualisation of the entire operation.

The jack and pack system involved employing self-propelled modular trailers (SPMTs) with strategically positioned cassette towers. Four internal towers placed on the SPMTs, and four external towers positioned on the ground adjacent to the trailers. By adding or removing jacking cassettes, the team could control the height of the mill by redistributing the load between the internal and external towers via the SPMT’s hydraulic suspension.

The process commenced with the removal of the ageing mill. The internal cassette towers were pre-assembled to a specific height on the SPMT, which was then manoeuvred underneath the mill and then raising it until the mill was clear of its foundation. Leveraging the exceptional steering capabilities of the SPMT, the mill was then transported off site, skillfully navigating congested areas. The process was then reversed to install the new ball mill.

Liam Bradburn, Mammoet’s Engineering Manager, emphasised the role of Mammoet’s Move3D software in enabling the safe and successful replacement of the mill. “The customised jack and pack system allowed us to manoeuvre the mill in and out of the live plant with minimal disruption to the existing infrastructure and ongoing production.”