Process for preparing raw sulfite acid

Claim 1

A CONTINUOUS PROCESS FOR PREPARING RAW SULPHITE ACID WHICH COMPRISES, IN AN ABSORPTION ZONE, PASSING A GAS CONTAINING SO2, AND OBTAINED SUBSTANTIALLY FROM A FURNACE PRODUCING SO2, OVER ACID ALREADY HAVING THE DESIRED CONTENT OF BISULPHITE, MOVING A SOLID BODY ALTERNATINGLY THROUGH SAID ACID AND GAS IN SAID ZONE FOR INTIMATELY MIXING SAID ACID AND GAS TO INCREASE THE FREE SO2 CONTENT OF SAID ACID, THE SUPPLY OF SO2 TO SAID ABSORPTION ZONE AND THE MOVEMENT OF SAID SOLID BODY BEING ADJUSTED IN SUCH A WAY THAT AT MOST 25% OF THE TOTAL SO2 CONTENT OF THE GAS IS ABSORBED, CONDUCTING THE REMAINING SO2 CONTAINING GASES FROM SAID ABSORPTION ZONE TO A BISULPHITE PRODUCING ZONEE CONTAINING A BASIC MATERIAL OF AT LEAST ONE METAL OF THE GROUP CONSISTING OF CALCIUM, AND SODIUM, CONTINUALLY SUPPLYING WATER TO SAID BISULPHITE PRODUCING ZONE IN A QUANTITY CORRESPONDING TO THE QUANTITY OF RAW ACID TO BE PRODUCED, CONTACTING THE SAID SO2 CONTAINING GASES IN SAID BISULPHITE PRODUCING ZONE WITH SAID WATER AND SAID BASIC MATERIAL TO PRODUCE AN ACID HAVING THE DESIRED CONTENT OF BISULPHITE, THE CONDITIONS OF ABSORPTION IN SAID BISULPHITE PRODUCING ZONE BEING ADJUSTED IN SUCH A WAY THAT THE SO2 CONTENT OF THE GAS IS PRACTICALLY COMPLETELY ABSORBED, AND PASSING THE ACID WITH THE DESIRED CONTENT OF BISULPHITE THUS PRODUCED TO SAID ABSORPTION ZONE.