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On the operability of the Sherritt-Gordon ammonia leach at the Kwinana nickel refinery

Woodward, Travis (2014) On the operability of the Sherritt-Gordon ammonia leach at the Kwinana nickel refinery. PhD thesis, Murdoch University.

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The objective of this thesis was a study of the operability of the leaching process at the Kwinana nickel refinery. The refinery makes use of the Sherritt-Gordon process for producing London Metal Exchange-grade nickel briquettes and other products. Like all industrial operations, the refinery embodies a considerable investment, demanding optimal performance in order to remain profitable. The 3-stage, 6-autoclave ammonia leach there is the most important process in the refining operation, yet it is also the most complex and least understood. A thorough understanding of the leach is critical in promoting optimal refinery operation, thus provoking the present work.

The operability study was conducted on the basis of mathematical modelling and computer simulation, focusing on steady-state operation. An examination of the chemistry of the Sherritt-Gordon ammonia leach was undertaken, leading to a chemical reaction system suitable for robust modelling. A mathematical model of the process was developed, which allowed for the construction of a computer program for the purpose of process simulation. The model was firstly used in a stand-alone fashion to examine the chemistry and operation of the leach. The model was secondly incorporated into an optimisation problem, augmenting the program as required, and used to investigate the impact of process disturbances and set-point changes on leach performance for a wide range of operating conditions.

On a fundamental basis, the following transpired from this work: (1) a new understanding of the Sherritt-Gordon ammonia leach chemistry, (2) a novel method for modelling generic leaching reactors, and (3) a modelling framework for the Sherritt-Gordon ammonia leach. On a practical basis, the operability study of the ammonia leach generated (1) significant insight into process behaviour, which may be directly used by refinery staff to support performance optimisation and process control, and (2) a series of recommendations for unlocking hidden capacity, which should form the basis of future efforts to optimise refinery operation.

Item Type: Thesis (PhD)
Murdoch Affiliation(s): School of Engineering and Information Technology
Supervisor(s): Bahri, Parisa
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