GB176400A - Improvements in the recovery of ammonia in the ammonia soda process - Google Patents

Abstract

176,400. Pattison, E. W., (Mathieson Alkali Works, Inc.). Sept. 3, 1920. Ammonia; ammonium sulphide; sodium bi-- carbonate.-In a modified ammonia-soda process,. ammonia is liberated from the ammonium chloride by treating with an alkaline earth sulphide and converting the resulting ammonium sulphide into ammonia by means of an alkali. In the preferred method of working, feeder-liquor from the bicarbonate filters after passing through the heater B wherebv the ammonium bicarbonate present is decomposed, passes to the distilling section A through a pipe 3, whereupon ammonium sulphide and barium chloride are produced by interaction with barium sulphide obtained by lixiviation of black-ash and introduced through the pipe 4. The ammonium sulphide passes to the receptacle C and is treated with caustic soda to give sodium sulphide and free ammonia which is conveyed to the absorbers. Sodium carbonate may be employed in place of caustic soda, but slight excess is required which contaminates the sodium sulphide, and also ammonium carbonate instead of ammonia is produced. The sodium sulphide liquor is removed through the pipe 10 and is crystallized. The barium chloride is withdrawn through pipe 6 and is treated either with a little hydrochloric acid to convert the small quantity of barium sulphate present into barium chloride or is treated with carbon dioxide to precipitate the sulphide as carbonate. The barium chlorideis separated from the sodium chloride present by fractional crystallization. Alternatively, theammonium chloride is crystallized from the feeder liquor, and its solution in water treated with alkaline-earth sulphide.