| 摘要 |
PURPOSE:To produce dense magnesium hydroxide having large particle diameter and high sphericity, by reacting a water-soluble magnesium salt with ammonia under specific condition, agglomerating a part of the particles, and crystallizing the secondary particles having definite particle diameter and specific surface area. CONSTITUTION:Ammonia gas is introduced into an aqueous solution of a water- soluble magnesium salt such as magnesium chloride to crystallize the crystal of magnesium hydroxide. The crystallization load of the magnesium hydroxide in the above process is adjusted preferably to <=500kg/m<2>.h, and the concentra tion of the magnesium hydroxide slurry in the crystallizer is made to be 1-6wt%. The primary particles are agglomerated to form secondary particles of magnesium hydroxide in a nearly spherical form with an average particle diameter of 5-500mu and a specific surface area of 25-1m<2>/g. Since the particle is composed of a number of flaky primary particles collected along various directions orienting the flakes almost radially from the center toward the out side, the produced secondary particle takes a spherical form in appearance.
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