METHOD OF PRODUCING CALCINED SODA Russian patent published in 1997 - IPC

FIELD: inorganic chemicals production. SUBSTANCE: method includes production and purification of rock salt solution, firing of carbonate raw material, separation of hydrocarbonate suspension, calcination of sodium hydrocarbonate, and stripping of ammonia and carbon dioxide. Method is distinguished with that firing, distillation, and calcination gases are combined at a temperature not lower than 60 C, gas mixture is cooled with simultaneously removing reaction heat, and ammonium bicarbonate obtained is mixed with purified sodium chloride solution to produce hydrocarbonate suspension. Gas mixture is cooled to a temperature not higher than 25-35 C. Cooling of mixture with simultaneously removing reaction heat is conducted according to one of the following procedures: using circulating recuperative attachment, neutral organic heat carrier, ammonium bicarbonate suspension, or sodium hydrocarbonate suspension each cooled before entered into process, cooling of gas mixture being performed in direct contact with indicated heat carriers. Amount and makeup of circulating suspension are maintained by way of introducing a part of filtrate into it. When sodium hydrocarbonate suspension is used, newly formed part of it is subjected to separation. When attachment and organic heat carrier are used, gas mixture is supplemented with steam. Steam and firing gases are introduced in amounts providing their being in excess to stoichiometrically needed amounts for ammonium bicarbonate formation. When cooled, gas mixture is washed with sodium chloride solution. To gas mixture, prior to be washed, gases sucked off out of filtration unit are admixed. Washed solution is treated with calcination gases or the same gases are used to treat combined sodium chloride and ammonium bicarbonate solution. EFFECT: enhanced efficiency of process. 12 cl