| 摘要 |
<p>PURPOSE:To simply and efficiently recover Ru as chloride, by a method wherein the coating layer containing Ru oxide on a metal electrode substrate is dissolved in molten alkali metal hydroxide containing an oxidizing agent and, after the resulting mixture is dissolved in water, an oxidizing agent is added to the obtained solution while RuO4 generated by vacuum distillation is conducted into hydrochloric acid. CONSTITUTION:The aforementioned coating layer containing Ru oxide is dissolved in molten alkali metal hydroxide (e.g, KOH) containing an oxidizing agent (e.g., NaNO3) at about 350-600 deg.C and peeled off. The amount of the aforementioned oxidizing agent is pref. adjusted to abot 20% or less on the basis of the total amt. of melted material. In the next step, the melt containing Ru obtained in the aforementioned melting process is cooled and dissolved in water by adding water to said melt in an amount of about 2-10 times on the basis of the amt. of the melt and, thereafter, an oxidizing agent (pref. Cl2 gas) is added to the resulting solution to perform vacuum distillation. The generated RuO4 gas is introduced into hydrochloric acid with concn. of about 10-35% and Ru is recovered as RuCl4 and RuCl3 by dissolution reaction. The solution of these high purity Ru chlorides can be reused in preparing a metal electrode and, according to necessity, recovered as a conc. solid or as metal Ru after reduction treatment.</p> |
