Method and device for processing sludges containing alkaline earth metal sulphates and sulphates

摘要

Process for treating sludges containing aqueous sulphites and alkaline earth metal sulphates, with an SO₂ content not exceeding 45% by weight based on the weight of the sludge and with an SO₃ content of not more than 40% by weight. related on the weight of the sludge and the total content of sorbed and crystal-bound water not more than 80% by weight, based on the weight of the sludge, the sludge material is mixed in an enclosed space with a mineral acid selected from the group consisting of sulphuric acid, nitric acid and phosphoric acid, diphosphoric acid, hydrochloric acid or mixtures of them in a weight ratio of 1: 0.7 to 1 : 1.6 related to the weight of SO₂ contained in the sludge and allowed to react with stirring or mechanical kneading for 10 to 35 minutes to disintegrate the sludge material, heat it, convert the alkaline earth metal sulphites present in the sludge material to stronger acid salts and displace from SO₂ sludge material which is discharged outside the sludge treatment area and after SO₂ removal, the sludge material after reacting with acid or acids is mechanically kneaded in air for at least 5 minutes to solidify the sludge material and its simultaneous partial disagglomeration to grains smaller than 20 mm .