METHOD OF PRODUCING RED IRON OXIDE PIGMENT Russian patent published in 2018 - IPC C09C1/24 C09C3/06 C30B29/16 

FIELD: chemistry.

SUBSTANCE: method includes oxidative hydrolysis of aqueous solutions of iron sulphate (II) at a temperature of 15 to 40°C and pH of the reaction medium of 4 to 12 followed by hydrothermal treatment of the resulting suspension of iron oxyhydroxides (III) at a temperature of 160 to 230°C. And before the oxidative hydrolysis stage begins, additives are added to the reaction medium, which stabilise the crystal growth. Such additives are polyphosphates or sodium silicates in an amount of 1 to 50 mmoll per 1 mole of iron oxyhydroxide (III).

EFFECT: improvement of qualitative indicators of the red iron oxide pigment due to reduction of its polydispersity in 1,25-1,4 times in comparison with the nearest analogue.

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