BHPB Nickel West operates a nickel refinery at Kwinana in Western Australia. The tail gas scrubber removes ammonia from leach off-gas before emission to atmosphere.
The objective of the project was to replace the existing ammonia tail gas scrubber, which was at the end of its useful life, with a new scrubber designed for increased capacity, to maximise ammonia capture for reuse in the process and to remove ammonia from waste gas streams to below the legal emission limit. The new scrubber has 35% increased capacity to process up to 60,000 Nm3/hour of tail gas at 5% ammonia by volume and achieves emissions below the target of 0.2% ammonia by volume.
The project involved replacing the entire existing scrubber shell, shell internals, silencer and instrumentation, along with associated modifications and upgrades to the cooling of inlet gas.
Work included changes to all services and utility requirements, including electrical power, process water, cooling water, demineralised water, instrument and utility air. Design work included point cloud scanning of the existing facility to model it in 3D CAD allowing accurate design and fabrication of new equipment, detailed assessment of the existing structure and foundations for the loads of the new larger scrubber vessel and require facility modifications.
A three-phase approach was taken for the project. Lycopodium initially completed a Selection Phase Study which assessed the various solution options. A key area of design was the process simulation modelling of technology options and process conditions leading to the optimum technology and process conditions being defined as a basis for design.
Upon approval of the recommended solution, Lycopodium completed a Definition Phase Study, which involved completion of preliminary design and capital cost estimate as well as project execution plans. This provided BHPB Nickel West with the necessary information to apply for capital funding approval.
Following funding approval, Lycopodium completed detailed design, provided procurement services and technical support. BHPB Nickel West supervised installation and carried out commissioning.
The site works were implemented during a 10-day shutdown in November 2012.