A potential process for the neutralisation of industrial waste acids by reaction with olivine

Abstract

Industrial waste acids such as sulphuric and hydrochloric acid are produced in large quantities. This note deals mainly with waste sulphuric acid, although similar results have been obtained with hydrochloric acid. A method is described by which these acids can be neutralised using crushed olivine rock. This process produces silica. The heavy metals present can be precipitated from the resulting solution. The remaining clean magnesium-sulphate solution can be dumped at sea without adverse environmental consequences. The process has been patented (Dutch patent PCT NL 85/00026), and is being further developed in cooperation with Dutch industries. Silica, one of the major products of the process has been tested as an additive to concrete. An addition of between 5 and 10% silica greatly decreases the permeability of concrete, thereby increasing the resistance of concrete constructions under chemically aggressive conditions.