Recovery of sodium sulphate in production of iron oxide black pi

Details Recovery of sodium sulphate in production of iron oxide black pi Recovery of sodium sulphate in production of iron oxide black pi

1978-03-02

1979-11-06

Gantz, Delbert E.

Chemistry of inorganic compounds

Sulfur or compound thereof

Oxygen containing

423632, C01D 500, C01G 4902

Patent

active

041736249

ABSTRACT:
In the production of ferric oxide black pigments with the simultaneous recovery of sodium sulphate wherein ferrous sulphate is reacted with an alkaline sodium compound at a pH above about 6 and a temperature above about 50.degree. C., and the pigment formed is separated from the mother liquor containing sodium sulphate, the improvement which comprises conducting the reaction at a sodium sulphate concentration of at least about 20% by weight, after separation of the pigment cooling at least part of the sodium sulphate-containing mother liquor to a temperature of at most about 30.degree. C., thereby to crystallize sodium sulphate decahydrate, and separating the crystals. Air is preferably passed through the reaction solution to oxidize the precipitated pigment and, advantageously, make-up water is added to compensate for water carried off by the air. The end product mother liquor, containing an appreciable amount of sodium sulphate, is employed to dissolve ferrous sulphate for a subsequent cycle.

REFERENCES:
patent: 2631085 (1953-03-01), Bennetch
patent: 3706531 (1972-12-01), Cozza et al.
patent: 3970738 (1976-07-01), Matsui et al.
Kirk-Othmer, "Encyclopedia of Chemical Technology", Second Edition, vol. 18, (1969), pp. 502, 503.

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