Hydrometallurgy alumina

Crystallisation and precipitation

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Crystallisation is a separation and purification process used in the production of a wide variety of materials ranging from bulk commodities to specialty chemicals and pharmaceuticals.

The crystallisation process commonly involves simultaneous occurrence of a number of crystallisation mechanisms.

Photo of project scientist in lab coat and googles conducting a laboratory precipitation experiment.

Project scientist conducts a laboratory precipitation experiment to improve the understanding of problems in Bayer precipitation circuits.

Research focus

Our research focus includes:

  • improving fundamental understanding of crystallisation mechanisms such as:
    • nucleation – generation of new crystals in solution
    • crystal growth – deposition of solute from solution onto crystal surfaces
    • agglomeration – aggregation and cementation of smaller crystals to form larger agglomerates
  • advancing experimental techniques and tools for monitoring and quantifying crystallisation mechanisms
  • developing numerical procedures for the estimation of crystallisation kinetics and modelling of crystallisation processes  
  • integrating fundamental understanding of physicochemical processes with mathematical modelling to address complex process challenges 
  • developing numerical models of plant-scale crystallisers and crystallisation circuits.

Laboratory equipment

Our researchers use a range of specialised laboratory-scale crystallisation equipment to generate experimental crystallisation data under different operating conditions.

This equipment includes:

  • Taylor-Couette crystalliser
  • semi-continuous stirred tank crystalliser
  • batch controlled-cooling stirred tank crystalliser
  • Coulter Counter and AccuSizer particle size analysers
  • optical and scanning electron microscopy
  • automated titrator and other specialist on-site analytical equipment.

Science outputs

Our crystallisation and precipitation research has resulted in:

  • an improved understanding of gibbsite precipitation from caustic-aluminate solutions.
  • development of mechanistic models for gibbsite precipitation kinetics (through the AMIRA P521 project) 
  • quantification of the impact of process operating conditions and impurities on gibbsite precipitation kinetics
  • development of crystallisation process models and simulation tools to facilitate rigorous plant optimisation.