METHOD FOR PRODUCING YELLOW IRON OXIDE PIGMENT WITH CaCO3 PRECIPITANT

PROBLEM TO BE SOLVED: To provide a method for producing a yellow iron oxide pigment with comparatively dark L*value by precipitation method favorably using iron chloride (II) raw material. SOLUTION: The yellow iron oxide pigment is produced by a method of initially introducing an aqueous Fe(II) component solution having 55-220 g/L Fe concentration based on the introduced aqueous solution, adding α-FeOOH yellow nuclei, setting temperature at 55-85°C and oxidizing to form more α-FeOOH, wherein temperature during oxidation is 55-85°C and oxidation rate is 0.2-10 mol%/h product Fe(III), calcium carbonate and/or dolomite is added during or soon after oxidation as an aqueous suspension, powder or granule at 80-500 g/L concentration based on the suspension added as a precipitant, and pH at oxidation initiation is raised at 0.05-1.0 pH/h rate by continuously adding the precipitant till rising up to the pH rising end of pH 2.4-5.2. COPYRIGHT: (C)2005,JPO&NCIPI