Production of iron oxide seeds containing aluminum, used directly for red pigment production, involves adding aluminum component to ferrous chloride solution, heating, adding sub-stoichiometric amount of precipitant and oxidation

摘要

Production of iron (Fe) oxide seeds containing aluminum (Al), with alpha -FeOOH crystal structure and aspect ratio 2100-3100, comprises stirring 6-20 mole% Al component (based on Fe) into Fe-II chloride solution containing 20-100 g/l Fe (0.1-10 mole% Fe-III); heating to 30-60 deg C; adding 20-80% of the stoichiometric amount of precipitant (2-10 equivalent active/l); oxidation at 2-50 mole-%/hour and direct conversion to Fe oxide red pigment. Production of iron (Fe) oxide seeds containing aluminum (Al), with alpha -FeOOH crystal structure and an aspect ratio of 2100-3100, using Fe-II chloride (FeCl2) comprises: (a) adding 6-20 mole% Al component with respect to total Fe content to a stirred FeCl2 solution containing 20-100, preferably 40-65 g/l Fe, with 0.1-10 mole% Fe-III; (b) heating this mixture to a precipitation temperature of 30-60, preferably 35-50 deg C; (c) adding a precipitant (I) with an active content of 2-10, preferably 4-8 equivalent/l, so that the molar ratio of (Fe+Al)/(I) is 20-80, preferably 30-60% of the stoichiometry; (d) oxidizing the precipitated suspension with an oxidant, so that the oxidation rate of the Fe to be oxidized is 2-50, preferably 10-35 mole%/hour; and (e) using the seeds for direct production of iron oxide red pigment via alpha -FeOOH as intermediate stage without further isolation, after testing the properties.