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.
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).
MATSUURA HARUAKI
NUMATA HIROO
TOKYO INST TECH
Next Patent: UNIFORM PRESSURE PAD FOR ELECTRICAL CONTACT