Patent ID: 9061919
Filing Date: 2015-06-23
Classification: C01F,C01P,Y10T

Abstract:
1. A method for producing a magnesium oxide powder, comprising the steps: (A) providing a purified magnesium hydroxide slurry; (B) maintaining the purified magnesium hydroxide slurry at a temperature of 50 to 200° C. while stirring of 0.5 to 4 hours to perform a heat stirring treatment; (C) subjecting the heat stirring-treated first magnesium hydroxide slurry to filtration and washing with water to obtain a first magnesium hydroxide cake; (D) adding to the first magnesium hydroxide cake pure water in an amount of 5 to 100 times relative to the mass base amount of a dry magnesium hydroxide contained in the first magnesium hydroxide cake, and stirring the cake in the pure water to prepare a second magnesium hydroxide slurry, and subjecting the second magnesium hydroxide slurry to filtration and washing with water to obtain a second magnesium hydroxide cake; (E) repeating the step (D) further 1 to 20 times using the second magnesium hydroxide cake as a starting material instead of the first magnesium hydroxide cake to obtain a high-purity magnesium hydroxide cake; (F) dehydrating the high-purity magnesium hydroxide cake to obtain high-purity magnesium hydroxide wherein the high-purity magnesium hydroxide has a purity of 99.9% by mass or more and contains chlorine in an amount of 500 ppm by mass or less; and (G) increasing the temperature of the high-purity magnesium hydroxide in an air atmosphere at a temperature elevation rate of 2 to 20° C./minute and calcining the high-purity magnesium hydroxide at 500 to 1,500° C. for 0.2 to 5 hours to obtain a magnesium oxide powder.