Method and apparatus for the synthesis in a continuous manner of an aqueous solution of aluminum sulfate from a sludge of aluminium hydroxide and apparatus for adjust the temperature in the course of this synthesis

摘要

The process according to the present invention for the continuous synthesis of an aqueous aluminium sulphate solution from an aluminium sludge comprises the stages consisting in alternately introducing the aluminium sludge produced during a surface treatment operation of the aluminium, the residual sulphuric acid produced during the removal of a coating during the treatment and the aqueous sulphuric acid solution containing aluminium sulphate produced during the recovery of the sulphuric acid during the treatment into a plurality of reaction vessels, so as to subject these substances to a reaction in the vessels, respectively, while mixing them, stirring them and heating them at a temperature between 80 DEG C and the boiling point of the reaction solution, and, finally, in bringing part of the sulphuric acid solution containing the aluminium sulphate into at least one of the second to last vessels in order to adjust the pH value of the reaction solution in the last vessel to a level between 1.6 and 2.5.