| 摘要 |
PROBLEM TO BE SOLVED: To provide precipitated barium sulfate powder which is made to have small particle size, a narrow-width particle size distribution and excellent dispersibility by solving problems of the conventional method for reacting mirabilite or sulfuric acid with barium sulfide. SOLUTION: The barium sulfate powder is obtained by preparing a barium sulfide solution having≥50 g/L barium concentration as Ba, preparing an ammonium sulfate solution as a sulfate solution to be reacted with the barium sulfide solution, adding the ammonium sulfate solution corresponding to 0.8-2.5 equivalent ammonium sulfate to the barium sulfide at 30-60°C liquid temperature to obtain slurry containing a precipitate of barium sulfate, adjusting the pH of the obtained slurry to 11-13 by adding sodium hydroxide, aging the pH-adjusted slurry at 60-90°C liquid temperature, filtering the aged slurry, washing the filtered precipitate with water, drying the washed precipitate and crushing the dried precipitate. The obtained barium sulfate powder contains≤10 wt.ppm sodium, has pH 7.0-9.0, namely, is almost neutral to weakly alkaline, and has the narrow-width particle size distribution like a particle size distribution curve, which is measured by a laser diffraction method and shown in Fig.1, and excellent dispersibility. COPYRIGHT: (C)2008,JPO&INPIT
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