Method for the purification of sulphuric acid containing mercury
AssigneeBoliden Aktiebolag
InventorKarl-Axel Melkersson
Life of this patent
Estimating the term…
Abstract
The invention relates to a method of purifying sulphuric acid containing mercury in a plant for the production of sulphuric acid according to the contact process which involves drying moist roaster gases containing sulphur dioxide in at least two drying towers where the major part of the water content is absorbed in the first drying tower. The sulphuric acid containing mercury is in a quantity suitably measured to maintain the concentration between 70 and 80 percent by weight led to the first drying tower. To the second drying tower is led a sulphuric acid so that the concentration can be maintained between 95 and 103 percent by weight. The mercury is separated from a partial current from the circulating sulphuric acid in the first drying tower.
Claims14
A method of purifying sulphuric acid containing mercury and producing a substantially mercury-free sulphuric acid in a plant for the production of sulphuric acid according to the contact process, which involves drying moist roaster gases containing sulphur dioxide in at least two drying towers, where the major part of the water content is absorbed in the first drying tower, characterized in adding the sulphuric acid containing mercury wholly or partially deriving from sulphuric acid produced in another plant to a circulating sulphuric acid in the first drying tower, the quantity suitably measured to maintain a concentration of between 70 and 85 percent by weight;
- leading sulphur trioxide, oleum or sulphuric acid to a circulation circuit of sulphuric acid in the second drying tower so that the concentration can be maintained at between 95 and 103 percent by weight;
- leading a partial current from the circulating sulphuric acid in the second drying tower to the circulating sulphuric acid in the first drying tower;
- removing a partial current from the circulating sulphuric acid in the first drying tower;
- purifying said acid current by means of precipitating mercury;
- leading off said purified acid current as product acid or leading it to the absorber which is an integral part of a sulphuric acid plant using the contact process.
Dependencies are inferred from the claim text.