METHOD FOR PURIFYING A SOLUTION CONTAINING CALCIUM IONS, PHOSPHORIC AND NITRIC (HYDROCHLORIC) ACID, FROM IRON AND ALUMINIUM INCLUSIONS Russian patent published in 2022 - IPC C05B3/00 C01F11/00 C01G49/00 C01F7/00 

FIELD: agriculture.

SUBSTANCE: method for purifying nitric or hydrochloric acid solutions used in the production of mineral fertilisers, resulting from the action of excess solution of nitric or hydrochloric acid on calcium phosphate-containing natural ore, from iron and aluminium ions is characterised by the resulting solutions containing, mol/l: Ca²⁺ 0.1 to 5 , PO₄ ^3- 0.05 to 3, H⁺ 0.1 to 5, Fe³⁺ 0.01 to 1 , AI³⁺ 0.01 to 1, undergoing heat treatment for a time from 5 minutes to 24 hours at 50°C to 100°C so as to form insoluble compounds containing iron and aluminium ions, followed by the separation thereof by filtering or decanting.

EFFECT: possibility of significantly lowering the content of iron and aluminium compounds in acidic agents and/or tertiary calcium phosphate, intended for use as mineral fertilisers or as raw materials for producing mineral fertilisers.

5 cl, 1 ex