| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To produce high purity calcium carbonate having a low chlorine content and a low impurity metal content. <P>SOLUTION: The method for producing such high purity calcium includes: (A) a step of preparing calcium hydroxide slurry by reacting quicklime obtained by firing limestone with water; (B) a step of adding nitric acid to the calcium hydroxide slurry so that the slurry is adjusted to pH 9.5-11.5; (C) a step of obtaining a filtrate by ultra-filtering the solution obtained by adding nitric acid; (D) a step of depositing calcium carbonate by adding an alkali metal carbonate to the filtrate; and (E) a step of separating calcium carbonate by filtering the deposited calcium carbonate. <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
