METHOD OF PRODUCING SODIUM CYANIDE Russian patent published in 2019 - IPC C01C3/10 B01D53/14 B01D53/96 

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry. Method of producing cyanides of alkali metals in solid form involves absorption of hydrogen cyanide from reaction gas with an aqueous solution of an alkali metal hydroxide at temperature of 35–75 °C immediately after the reaction gas feed point at pressure of 1120–1600 mbar to obtain an aqueous solution of an alkali metal cyanide. Crystallisation is carried out by adding an alkali metal cyanide solution to an evaporative crystalliser which is heated by means of steam heating. On the contact surface of the heating element and the alkali metal cyanide solution, temperature of 60–100 °C is provided. Separation step is carried out by separation of the formed crystals of alkali metal cyanide from the mother solution using centrifuges of periodic action with knife discharge of the residue. Recirculation is performed in form of reverse feed X vol. % of separated mother solution for absorption and reverse feed (100-X) vol. % of mother solution at crystallisation stage. Separated alkali metal cyanide crystals are dried using a contact drier.

EFFECT: invention provides a completely closed production cycle in which there is no need to recycle a mother solution containing an alkali metal cyanide.

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