GB515374A - Improvements in and relating to the manufacture of ammonium sulphate - Google Patents

Abstract

515,374. Ammonium sulphate. OGDEN, G., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. May 30, 1938; No. 16146. [Class 1 (ii)] [Also in Group IV] Refers to the saturator process, in which ammonia or annnonia-containing gas is passed into a solution of ammonium sulphate and sulphuric acid, and consists in adding to the saturator an oil and a wetting agent having defined characteristics in order to obtain crystals of a good white colour. The oil should be stable, non-volatile and of lower density than the saturator liquor; the wetting-agent should possess high wetting and frustrating power in acid, neutral or alkaline media, good stability to acids and in concentrated salt solution and ready solubility in concentrated salt solutions. Creosote oil -from coal or coke oven tars is preferred, but kerosene, diesel oil and middle oils may be used. Wetting-agents having one or more sulphuric groups are specified. The oil may be added with make-up acid or otherwise, and the wetting-agent may be added with the oil or at other convenient point, e.g., it may be added to water used to wash the crystals, which is then introduced into the mother liquor. As shown, a saturator 1 is fed with mother liquor of sulphuric acid and ammonium sulphate from the tank 3 which liquor overflows through a seal pot 5 into a.tank 6 from which the mother liquor is recirculated to the tank 3 and made up with necessary acid. Ammonia-containing gases are introduced through the pipe 9 and waste gases leave by the pipe 10. A mixture of oil and wetting-agent is fed by a pipe 13 to a small annular trough 12 and overflows into the mother liquor. The oil is withdrawn from the. tank 6 by an overflow 14, purified and returned. Ammonium sulphate crystals are removed from the bottom of the saturator by an elevator 11, drained and centrifuged and the mother' liquor. therefrom returned to the saturator. .Specification 18,559/14, [Class 1 (ii)], is referred to.