METHOD OF PRODUCING BRICK-RED IRON OXIDE PIGMENT Russian patent published in 2021 - IPC C09C1/24 C01G49/06 C22B3/06 C22B3/08 

FIELD: chemistry.

SUBSTANCE: invention can be used in production of decorative varieties of concrete, ceramics and paint materials. To obtain iron oxide pigment from steel-smelting slag of converter production method, slag is ground and mixed with 35 % acetic acid solution in reactor equipped with mixer at rate of 100 rpm. Adding sodium hydroxide to the obtained solution to pH 8–9 with increasing temperature to 59 ± 1.5°C, settling for 4 hours. Solution of calcium, sodium, magnesium acetate is removed. Precipitate is washed at least 6–7 times with water in the reactor itself to pH 6. Solution from washing is connected to a solution of acetates. Method then includes adding to sludge 25 % sulphuric acid, turning mixer and increasing temperature to 80 °C is held for 24 hours for passage of reactions. Iron (II) sulphate solution which is stable for 4 hours is removed from the reactor. Obtained residue is washed 5–6 times with water in a reactor and drained in the form of pulp from the reactor. Solution from washing is added to a solution of iron (II) sulphate. Resulting solution is placed for 24 hours into muffle furnace at temperature of 180–200 °C. Then temperature is increased with rate of 10 °C/min to 650 °C is isothermally held for 2–3 hours. Obtained mass is milled in ball mill for 2–3 minutes, washed, dried at 80–100 °C and ground into powdered pigment.

EFFECT: invention makes it possible to carry out waste-free recycling of steel-smelting slag to obtain iron-oxide pigment of brick-red colour with content of α-Fe₂O₃ 93–95 %.

1 cl, 2 tbl, 1 ex