GB191220900A - Improvements in the Treatment of Gases from Coke Ovens and of like Gases and the Recovery of Products therefrom. - Google Patents

Abstract

20,900. Coleman, W. H. Sept. 13. Ammonium sulphate.-Gas from coke-ovens, retorts, producers, &c. is treated with a countercurrent of ferrous sulphate solution, so that at the gas inlet there is an excess of ammonia and sulphuretted hydrogen, and at the gas outlet an excess of ferrous sulphate, the maintenance of either or both of these excesses being effected by adding to the washer sulphuretted hydrogen and ammonia or ferrous sulphate obtained in later stages of the process. The liquor is then heated to render all the cyanogen compounds insoluble, the excess of ammonia and sulphuretted hydrogen expelled being returned to the gas, and the precipitate is separated, leaving. a solution of ammonium sulphate. The filter cake is treated with less dilute sulphuric acid than is equivalent to the ferrous sulphide present to obtain a neutral solution for re-use, and the sulphuretted hydrogen may be converted to sulphuric acid for use in the process or into sulphur.. The residue is freed from its remaining ferrous sulphide by more sulphuric acid, leaving the insoluble cyanogen compounds. The gases are freed from tar before entering the scrubers either above their dew-point, or after cooling. In the latter case, the ammoniacal liquor deposited is distilled with lime, the vapours being returned to the gas before it enters the scrubbers.