| 摘要 |
<p>PURPOSE: To efficiently and stably recover platinum group metals by adjusting an acid solution containing the platinum group metals recovered from waste catalyst to a specific equilibrium electrode potential and electric conductivity, using fluidized carbon particles as cathode and electrolyzing the solution at a specific voltage. CONSTITUTION: The waste catalyst supporting the platinum group metals is treated by an acid elution method using chlorine gas-hydrochloric acid, etc., to obtain an acid solution containing the eluted platinum group metals. Further, the catalyst after the treatment, is washed with a dilute acid of 1 normal of hydrochloric acid, etc., non-eluted platinum group metals on a support is leached. This leaching solution and the above acid solution are collected into an electrolysis weighing vessel 2 to make them the electrolyte. Then, chlorine gas is added while stirring the electrolyte with a stirrer 1, and the equilibrium electrode potential and the electric conductivity are adjusted to in the range of 550-650mV and 180-200m.s/cm, respecitively. This electrolyte is fed from the bottom part of a fluidized bed type electrolyzing vessel 5 with a pump 3, and while fluidizing the carbon 4, the voltage of >1.8V to <2.2V is impressed between the fluidized carbon 4 and the anode through a cathodic cylinder to execute the electrolysis and the platinum group metal therein is precipitated on the carbon 4.</p> |
