DEVELOPMENT OF A LABORATORY SEMI-CONTINUOUS GIBBSITE PRECIPITATOR

The development of a laboratory semi-continuous gibbsite precipitator is described. Lab-scale precipitation represents an essential tool in generating experimental information required for improvements in gibbsite precipitation process design, control, and optimisation. It provides an important means for studying gibbsite precipitation mechanisms and effects of different process parameters on precipitation yield and product quality.

The use of a relatively complex experimental setup, such as semi-continuous precipitation (SCP), may provide experimental data that are easy to interpret and directly relevant to the plant. In the SCP setup developed in this work, four important precipitation variables are controlled: (i) solution supersaturation, (ii) solids concentration, (iii) total volume, and (iv) precipitation temperature. Building this experimental unit required development of customised control software to ensure continuous in-line process monitoring and real-time process control. Data from semi-continuous gibbsite experiments were used to extract gibbsite precipitation kinetics, such as crystal growth, nucleation, and agglomeration.