METHOD FOR PRODUCTION OF IRON OXIDE PIGMENT AND UNIT FOR ITS REALIZATION Russian patent published in 1995 - IPC

FIELD: production of iron oxide pigment. SUBSTANCE: method for production of iron oxide pigment includes charging into reactor 1 of electroerosion dispersion of pellets of metallic iron, iron chips or pieces of plain steel, filling with water, and applied to electrodes is pulse voltage from source 2. Erosion products are directed to hydrocyclone 3 for separation of suspension of dispersed iron particles from nondispersed iron particles. Decrease of iron in reactor 1 is replenished from metering device 5. Iron-containing suspension is filtrated by filter 6 and filtrate is fed to filtrate collector 8, water is added and product is supplied to reactor 1 of electro-erosion-dispersion. Iron-containing paste from filter 6 is fed to oxidizing reactor 7 and water or filtrate is added. Suspension contains solid phase in the amount of 10-20 mas. Passed through suspension is carbon dioxide gas with stirring for 6-24 h, then, air or oxygen is passed through for 1-24 h. Oxidized suspension is filtrated by filter 9. Filtrate is supplied to collector 10 and with added water is directed to oxidizing reactor 7. Precipitant is thermally treated in furnace 11 and ground in mill 12. Process is free from harmful effluents to environment. Pigment features the following characteristics:content of iron compounds (in terms of Fe₂O₃) 98 mas. volatile and water-soluble substances none; hiding power 7.0 g/sqm; water suspension pH 7; oil absorption 30 g/100 g of pigment; dispersed particle size 28 mcm; residue insoluble in HCl is less than 0.1 mas. EFFECT: higher efficiency. 2 cl, 1 dwg, 1 tbl