Patent ID: 6254846
Filing Date: 2001-07-03
Classification: B01D,C01D,C04B,Y02W

Abstract:
In a process for purifying fumes laden with ash, originating from the incineration of waste which contains heavy metals, sodium chloride and organochlorine residues, and for manufacturing an aqueous sodium chloride solution, in which processin a first step, the fumes are subjected to a dust-removal operation, from which fumes freed of dust and ash containing sodium chloride and heavy metals are collected separately;in a second step, the fumes freed of dust are subjected to a treatment with a basic reagent comprising more than 50% by weight of a sodium compound, said treatment being selected from a dry-route treatment and a semi-wet-route treatment, and a gas laden with dust containing sodium chloride and heavy metals is collected;in a third step, the gas is subjected to a dust-removal operation, from which a gas freed of dust and the dust are separately collected;in a fourth step, the dust is dispersed in water and an aqueous medium comprising an aqueous sodium chloride solution is collected; andin a fifth step, the aqueous medium is subjected to purification; the improvement which comprises:washing said ash from said first step with a sufficient amount of water to dissolve the sodium chloride of the ash, said washing being carried out in such conditions that the water collected from the washing has a pH greater than 8; andsaid water of said fourth step comprising the water collected from the washing of the ash wherein the ash collected from said washing is subjected to an inertization process in which a reagent selected from phosphoric acid and alkali metal phosphates is added to the ash.