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Who we are :

Industrial crystallization research was initiated in the Department of Chemical Engineering in 2000 and the Crystallization and Precipitation Research Unit was formally accredited by the university in 2006.

Although industrial applications of crystallization and precipitation have a long history and precipitation has been studied scientifically since the 1930’s, understanding of this operation is still very limited. For this reason, the main aim of the Research Unit is to advance existing fundamental knowledge in the fields of crystallization and precipitation, especially related to the South African and International mineral processing and extractive metallurgy industries.

The unit focuses on two main areas of research:

  1. Optimising precipitation in hydrometallurgical processes. Our work on both Rhodium and Mixed Metal Sulphide precipitation are examples of this.
  2. Development of innovative technologies for mining wastewater treatment. Our Eutectic Freeze Crystallization project is an example of this.

The tools used in the research include modelling and simulation approaches to industrial research, such as the particle rate process approach for modelling of industrial crystallization processes; aqueous chemistry modelling and computational fluid dynamics modelling. All of these modelling techniques are aimed at deepening the understanding of these chemically complex, multiphase processes.

What we do: Research Focus and Project Areas

Eutectic Freeze Crystallisation
• Developing a continuous Eutectic Freeze Crystalliser to treat multi component hyper saline brines
• Investigating the factors affecting phase separation in Eutectic Freeze Crystallisation
• Salt purity and recovery in Eutectic Freeze Crystallisation
• Ice purity and recovery in Eutectic Freeze Crystallisation
• Factors affecting purity, recovery and hydrate formation of salts
• Integrated gProms model for batch Eutectic Freeze Crystallization
• Kinetic aspects and residence time in the design and control of a Continuous Eutectic Freeze Crystallization process

Rhodium Deta Precipitation
• Modelling semi batch precipitation of Rhodium Deta

Fundamentals of precipitation processes in water treatment
• Measurement of growth and aggregation kinetics of fine particles
• Developing methods to measure and model aggregation kinetics in precipitation systems
• Developing methods to measure nucleation and growth rates in sparingly soluble systems
• Computational Fluid Dynamics modelling of solid suspension behaviour

Metal Sulphide and Hydroxide Precipitation
• Removal of metals from industrial effluents and acid mine drainage using metal sulphide and hydroxide precipitation
• Precipitation using fluidized beds

Selenium precipitation thermodynamics and kinetics
• Selenium recovery
• Measurement of nucleation kinetics