Metallgesellschaft Aktiengesellschaft

Chemie Linz Aktiengesellschaft

Alfred Garber

Alfred Schmidt

Paul Wiesner

Hans-Martin Stonner

Ferdinand Weinrotter

Fritz Wohler

Hans M Stonner

Karlheinz Wegleitner

Josef Herbert Hatzl

Rudolf Sykora

Alan Sinclair

The aqueous effluent liquors from gasification or de-gasification of coal are extracted with a water-insoluble solvent and the extract is processed to recover the solvent. The aqueous residue is treated to remove NH.sub.3 in a driving-off column. The invention adds the steps of

Processing aqueous effluent liquors from degasification or gasification

Pure, concentrated ammonia is recovered from aqueous liquors by stripping off gas water, de-acidifications, scrubbing and withdrawing ammonia from the top of a scrubbing column.

Continuous process for recovering pure, concentrated ammonia

Guanidine carbonate is isolated from dilute aqueous solutions containing guanidine, urea, pyrolysis products of urea, ammonia and carbon dioxide, by evaporation of the solution at a temperature of 80.degree. to 130.degree. C until a guanidine carbonate content of 20g/l and a pyrolysis products content of not more than 28g/l at 80.degree. C or not more than 128.degree. g/l at 30.degree. C is achieved, without exceeding a heating time of 6 hours at the upper temperature limit, separation of the precipitated pyrolysis products, subsequent cooling to not more than 45.degree. C, addition of ammonia to an ammonia content of 15 to 30 % by weight and separation of the precipitated guanidine carbonate.

Recovery of guanidine carbonate from aqueous solutions

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Alfred Garber