| 摘要 |
<p>PROBLEM TO BE SOLVED: To recover rare-earth elements in a state of metals, wherein a high temperature operation is not necessary, corrosion of materials is low, and selec tion of materials is easy. SOLUTION: After dismantling nickel-hydrogen storage alloy for secondary battery already used and having taken out the hydrogen storage alloy of a negative electrode, the hydrogen storage alloy is turned into a positive electrode, and immersed into a fused salt in a fused-salt electrolysis vessel together with the negative electrode. Voltage is applied between both electrodes, and electrolysis is performed, and the rare-earth elements of the positive electrode are made to be dissolved (this is referred to as anodic dissolution process). After having separated the dissolved rare-earth element ions from other impurity ions in the fused salt, the dissolved rare-earth elements are made to be deposited at the negative electrode by electrolytic reduction, and made to be collected as metals (this is referred to as negative electrode recovery process).</p> |
