THE MECHANISM OF SODIUM GLUCONATE POISONING OF GIBBSITE PRECIPITATION

Sodium gluconate was used as a model compound in the poisoning of gibb site precipitation from caustic aluminate solutions. Experiments were performed to examine the relationship of seed surface area and sodium gluconate dose to the Induction period and precipitation rate, The res ults suggest that growth rate suppression is a surface process and tha t it results from a reduction in the available surface area and not fr om a change in surface activity. The mechanism of poisoning was inferr ed from SEM micrographs, and by using measurements of the growth rate and induction period for both poisoned and unpoisoned gibbsite precipi tations.