METHOD FOR PREPARING IRON-OXIDE PIGMENTS Russian patent published in 2003 - IPC

FIELD: inorganic chemistry, chemical, paint and varnish industry. SUBSTANCE: solution of FeCl₂ in concentration 100 g/dm³ is treated with solution of NaOH in concentration 80 g/dm³ and air oxygen in the presence of damp clay slimes from potassium production as an inert carrier. Ratio slime : iron in the end product = 1 : (0.2-0.8). Suspension temperature is 80 ± 5 C, synthesis time is 45-50 h. Precipitate is filtered off, washed out and dried obtaining shell iron-oxide yellow pigments with covering powder 20 g/m². Filtrate is fed under hypochlorite pulp layer containing 40-80 g/dm³ of Ca(OCl)₂ and 10-30 g/dm³ of CaO being amount of filtrate is taken so to provide pulp pH ≥ 9. Pulp is treated with 0.2% solution of polyacrylamide, precipitate is filtered off, washed out with reusable solutions, water, dried at 100 ± 5 C, ground, calcined at 550 ± 5 C obtaining iron-oxide pigment corresponding to requirements to pigments "iron minimum" (iron oxide). Degree of iron extraction from filtrate is ≥ 99.9%. Invention allows utilizing slimes from potassium manufacture, to obtain quality iron-oxide pigments, to expand raw base and to enhance degree of iron extraction. Invention can be used for preparing enamels and dyes. EFFECT: improved preparing method. 3 cl, 2 ex