GB133452A - - Google Patents

Abstract

133,452. Broxburn Oil Co., and Findlater, R. H. Oct. 11, 1918. Carbon.-The carbonaceous residue of the distillation of bituminous shales, cannel coal, &c. is ground, washed, and digested with sulphuric, hydrochloric, nitric, or hydrofluoric acid in a digester 5, the mixture is filtered in a press 13, and the filter-cakes digested in a digester 60 with caustic soda, the carbon being filtered off in a press 63 and washed with water, dilute acid, and then water. Alternatively, the material may be treated first with acid, as described above, then with sodium carbonate, in which case some silica separates on cooling, and then with caustic soda. The acid extract collected in tanks 11 is filtered in a press 18 to remove any calcium sulphate which separates during cooling, and is then passed to saturators 24 arranged in two groups A, B and C, D used alternately. Ammoniacal gases which may be derived from the shale distillation are passed in by a pipe 26 to the lower saturator A, the outlet gases passing by a pipe 27 to the saturator B, leaving finally at 28. When the liquor in A is filtered in a press 33, the liquor from B is passed into A, and fresh liquor is run into B. Alternatively, ammoniacal liquor may be used for this precipitation. The press-cakes from the press 33, consisting of alumina and iron hydrate, are digested with caustic soda in a digester 39, iron hydrate being filtered off in a press 42, and sodium aluminate solution being passed through a tank 46 and pipe 48 to towers 49, in which it is treated with gases containing carbonic acid, the alumina being finally separated in a press 53, while the sodium carbonate may be caustified for re-use. Any ammonia evolved in the digester 39 is passed by a pipe 67 into the saturators. The caustic soda extract from the digester 60 is concentrated for sale as sodium silicate. The ammonium salt solution from the press 33 is withdrawn at 35 and evaporated.