GB1145390A - Process for manufacture of hydrochloric acid - Google Patents

Abstract

1,145,390. Hydrochloric acid; alkali metal sulphates. WOODALL-DUCKHAM Ltd. 3 Nov., 1967 [8 Nov., 1966]. No. 50004/67. Heading C1A. In the process of the parent Specification, wherein HCl is produced by continually feeding NaCl or KCl and H 2 SO 4 into a boiling aqueous reaction mixture in a vessel, and permitting escape of HCl gas, aqueous reaction mass is continually withdrawn from said vessel and heat-treated to complete the reaction of 1 or 2 moles of salt with 1 mole of H 2 SO 4 . In Fig. 1, HCl gas is formed by reaction of salt and H 2 SO 4 in vessel 1, as described above. In the production of a bisulphate by-product, reaction mass from 1 passes through pump 8 to the head of HCl stripping tower 9, which it descends, at its boiling-point, in countercurrent to air and/or steam from inlet 10, so that the reaction between 1 mole of salt and 1 mole of H 2 SO 4 may go to completion, and so that HCl gas is stripped from the mixture to give a substantially chloride-free bisulphate product. Two alternative forms of HCl stripping device are described. In the production of a sulphate by-product, the reaction mass passes (instead of to a stripping device such as 9), to a spray roaster, in which it is sprayed in countercurrent to ascending hot gases at such temperature that the reaction between 2 moles of salt and 1 of sulphuric acid may take place to give a substantially chloridefree sulphate, which is removed as product, whilst the exhaust gases are scrubbed with water to remove HCI as an aqueous solution which may be recycled to vessel 1.