Yarwun Unit 2 Pit Remediation

Overview

Constructed in 2002, the Rio Tinto Yarwun alumina refinery produces approximately 3 million tonnes of alumina annually, which is shipped to various customers worldwide. As part of the refining process, pits are used to collect caustic sludge, which is disposed of in compliance with regulations. Over time, the corrosive nature of this material led to the deterioration of the concrete walls and floor, exposing the reo bar and causing concrete cancer. Pructon was engaged to undertake remediation works on the pit, including the installation of steel plates and high-strength Renderoc G grout to enhance the longevity of the structure. Additionally, Pructon was responsible for restoring the steel pipework to its original state, with fabrication of the large-bore pipework completed at our Gladstone workshop and installed during a planned shutdown period.

Scope of Work

• Project Planning and Design Review: Comprehensive planning and design review were conducted to ensure efficient project execution.
• Material Acquisition and Quality Checks: All necessary materials were sourced and subjected to quality checks prior to site mobilisation.
• Site Mobilisation and Establishment: The site was established and mobilised to facilitate the commencement of remediation activities.
• Pit Examination and Scaffolding Installation: Detailed examination of the pit was performed, followed by the installation of scaffolding to ensure safe working conditions.
• Remediation of Inlet Channels: High-pressure water blasting was employed to remove contaminants and scale build-up. Loose concrete was removed, followed by a 20mm saw cut around the perimeter, application of mortar, and installation of Fosroc Renderoc G with reinforcing steel.
• Remediation of Vertical Walls: Similar high-pressure water blasting techniques were utilised to address the vertical walls. Exposed steel reinforcement was treated with Fosroc Nitoprime Zinrich, followed by 20mm saw cuts, installation of threaded anchors, application of Fosroc Renderoc G, installation of steel plates to anchors, and final application of Fosroc Primer 13 and Fosroc Nitoseal SC600.
• Platform and Handrail Installation: Removal of the old platform and installation of new handrails over the sump area were completed to enhance safety.
• Site Demobilisation: The site was demobilised upon completion of all works.

Outcomes and Benefits

• Improved Environmental Safeguards: Enhanced safeguards were established to mitigate potential environmental impacts from the caustic materials.
• Increased Longevity of the Pit: The installation of steel plates has significantly improved the durability and longevity of the pit.
• Timely and Cost-Effective Delivery: The project was successfully delivered on time and under budget, demonstrating Pructon's commitment to efficiency and quality.