Process for producing highly pure magnesium hydroxide
AssigneeAsahi Glass Company, Limited
InventorsKeiichi Nakaya, Kunio Tanaka
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Abstract
A process for producing highly pure magnesium hydroxide, which comprises reacting magnesium hydroxide starting material containing impurities, with an aqueous solution containing a water-soluble calcium salt and carbon dioxide to form an aqueous solution containing a magnesium salt and calcium carbonate precipitates whereby said impurities are transferred to the precipitates, filtering off the precipitates, then reacting the aqueous solution containing the magnesium salt, with ammonia to form a slurry comprising magnesium hydroxide solid and an aqueous solution containing an ammonium salt, and filtering the slurry to obtain highly pure magnesium hydroxide solid and an aqueous solution containing the ammonium salt.
Claims12
A process for producing highly pure magnesium hydroxide, which comprises the steps of:
- reacting magnesium hydroxide starting material containing impurities, with an aqueous solution containing a water-soluble calcium salt and carbon dioxide to form an aqueous solution containing a magnesium salt and calcium carbonate precipitates whereby said impurities are transferred to the precipitates,
- filtering off said precipitates,
- decarbonating said filtered aqueous solution at a pH of from 1-5,
- reacting said decarbonated aqueous solution containing said magnesium salt, with ammonia to form a slurry comprising magnesium hydroxide solid and an aqueous solution containing an ammonium salt, and
- filtering the slurry to obtain highly pure magnesium hydroxide solid and an aqueous solution containing said ammonium salt.
Dependencies are inferred from the claim text.