Neutralization of waste acids with olivine-dissolution in organically contaminated acids

Olivine is the most easily weatherable, common silicate. The olivine proces s provides a promising way for the treatment of waste acids. Dissolution ex periments were carried out in organically contaminated waste acids and clea n acid. The rate of neutralization is accelerated in the presence of organi c contaminants (mainly sulphonate and its derivatives). In a vigorously sti rred batch reactor, the dissolution/neutralization process can be described satisfactorily using a model based on first order kinetics with respect to acid concentration. The first order rate constant is, however, found to be dependant of the starting acid concentration. The organic contaminants do not present an extra problem to silica washing, nor do they seem to have a significant effect on the silica texture. The SEM images of solid samples d o not show the existence of a precipitated silica layer, indicating that, i n a vigorously stirred reactor, a "surface-reaction-controlled" mechanism i s predominant.