THE SPONTANEOUS PRECIPITATION OF HYDRATED ALUMINA FROM ALUMINATE SOLUTIONS

Abstract

The rates of spontaneous precipitation of hydrated alumina from unseeded and metastable sodium aluminate solutions of a molar relation for Na2O/Al2O3 (α) ranging from 1.15 to 1.60 have been investigated. All precipitation curves showed autocatalytic characteristics with a pronounced induction period, during which no precipitation occurred, a steady state period, and a period of delayed precipitation. Empirical equations for calculating the maximum precipitation rate, for the time when this precipitation takes place, and for the amount of the precipitate at equilibrium for any of these aluminate solutions have been developed.