Abstract

The aim of the study is to propose an alternative process to boric acid generation by researching the dissolution kinetic of tincal in phosphoric acid solutions in high temperature, and to root the procuring of Na₂HPO₄ that is used commonly as byproduct in industry during the process. Reaction temperature, particle size, stirring speed, acid concentration and solid/liquid ratio were selected as parameters of dissolution rate of tincal. The tincal solubility has been found to increase by the temperature, stirring speed and decrease by the particle size and solid/liquid ratio. In the case of acid concentration, the solubility has been found to increase up to 2 M but decrease beyond this concentration. The solubility has been assigned to first order pseudo model. The activation energy has been found to be 46.21 KJ/mol. The solubility of tincal in phosphoric acid solution at high temperature has been defined by the following expression depending on reaction temperature, acid concentration solid/liquid ratio, stirring speed and particle size: -ln(1-X) = 1988.D^-0.78.C^0.22.S/L^-0.39.W^0.99.e^5558.4/T.t.

Key words: Tincal, phosphoric acid, leaching kinetics, high temperature.