Rotary Classifier – Alcoa Kwinana

Rotary Classifier – Alcoa Kwinana

As far as recent contracts go, GF Engineering’s track record of high-quality, industry-recognised projects was further solidified with its completion of the task to fabricate 2x rotary classifiers.

GF Engineering was awarded the project in September 2020. Work began immediately – the team got straight to work procuring the required plate/materials and began fabrication in early October.

The task, which was awarded to GF Engineering by Alcoa Kwinana, involved the fabrication of a rotary classifier. This involved a rotary outer can, rotary liner and bucket-wheel excavator – complete with flights. 2x of these assemblies were required.

No small task, the bucket-wheel measured 3380mm (outside diameter – OD), and shell 2460mm OD. Overall – 6735mm long. The weight – overall – totalled 19500kgs.

The refinery, which has operations spanning approximately 1,500-hectares of the Kwinana Industrial Area, contracted GF Engineering to complete the task due to our past history of fabricating these difficult items successfully and issue free.

“We always get excited when we have the opportunity to fabricate these items,” GF Engineering Managing Director Todd Jones said.

“It is a great project for our apprentice boilermakers and welders to be a part of as they learn many different aspects of how to fabricate correctly and accurately along the way.” Similar to the functionality of a cement mixer – the project formed a crucial part of the separation process with which the internal spirals separated the bauxite (mud slurry) from the process liquor which contains the alumina.

GF Engineering were able to undertake the entire fabrication including the machining of the tyres (where it sits on rollers onsite) in-house at its Naval Base site in WA.
The entire project was verified by third party surveying.

Bisalloy Protection 400/Hardox 450 Steel Materials (a quenched and tempered steel plate that is especially known for stellar wear resistance and impact toughness), were sourced and supplied by an additional third party company. Following its arrival at GF, the material was cut to appropriate size, and was then rolled into cans and welded. Spiral plates were marked up and cut and the difficult & methodical process of putting them altogether began.

“We always have a challenge of getting the variable pitch flights cut to the correct profile to suit the ID of the liner based on drawings from the 1980’s,” GF Engineering Project Manager Dan Williams said.

“However, with advancements in modern technology the challenge was easily overcome with our in-house drafting department creating a 3D model & organising a scaled model cut and fabricated to ensure accurate fitment. As technical as the project sounds we fabricated a spiral on a spiral, in a can, in a can.”

Demanding a high level of technicality, GF Engineering finished the project in early April 2021.