SPINEL TYPE FERRITE GRANULAR POWDER HAVING SPHERICAL TYPE AND ITS PRODUCTION

摘要

PURPOSE:To produce the titled powder which has a spherical shape and less flocculation properties among the mutual grains by passing an O2-contg. gas into an aq. soln. contg. hydroxide of Fe<2+> and M<2+> in the presence of water soluble silicate to oxidize it and adding alkali hydroxide in the amount of specified range. CONSTITUTION:Hydroxide of Fe<2+> and M<2+> (M<2+> is Mn, Zn, Cu, Ni, Co, Mg and etc.) is oxidized by passing an O2-contg. gas while heating it at 70-100 deg.C into a reacted aq. soln. of Fe<2+> salt and M<2+> salt contg. hydroxide of Fe<2+> and M<2+> which is obtained by allowing an Fe<2+> salt aq. soln. and an M<2+> salt aq. soln. contg. <=50mol% M<2+> for Fe<2+> contained in the aq. soln. to react with alkali hydroxide having 0.80-0.99 equivalent for total quantity of Fe<2+> and Mn<2+>. On such occasion, water soluble silicate is allowed to exist by 0.1-50atom% expressed in terms of Si for Fe<2+>. Then >=1.00 equivalent alkali hydroxide for the total quantity of Fe<2+> and M<2+> remaining in the reacted mother liquid after the oxidation is added to the hydroxide of Fe<2+> and M<2+> under the same conditions as this heating and oxidation conditions. Thereby spinel type M<2+>xFe<3+>2O4 grain (0 bulk density is formed.