METHOD OF PREPARING SHELL PIGMENT Russian patent published in 1998 - IPC

FIELD: production of inorganic pigments. SUBSTANCE: shell ferric oxide pigment applied in preparing various varnish-and-dye materials, in particular, for dyeing synthetic leather, in plastics production, in rubber industry, when manufacturing colored building concretes and mortars, is prepared as follows: ferric sulfate solution is treated by suspension of nuclei and by oxidant, after which aqueous pigment paste is filtered away and dried. Concentration of ferric sulfate is 240-300 g/cu.dm and aqueous suspension contains 300-450 g/cu. dm of slag powdered industrial-grade belite. Process is conducted to achieve pH 3.4-7 and, pigment precipitated, additional portion of belite suspension is added in amount 0.1-0.2 solution weight. When yellow pigment is to be prepared, ferric sulfate solution is treated by the same suspension at pH 3.4- 4.0; for red pigment, pH 5-6 is necessary. When black pigment is desired, above-mentioned treatment is conducted at pH 6.5-7.0 at 70-75 C with oxidant (e.g. potassium chlorate) added. EFFECT: 2 to 3 times reduced consumption of ferric sulfate, waste water does not require neutralization, and consumption of pigment in paint production reduced by 30-40%. 4 cl, 1 tbl