Patent ID: 6890417

Claim:
An apparatus for refining alkaline solution to refine the alkaline solution using an electrolytic bath, comprising: an electrolytic bath divided into an anodic chamber and a cathodic chamber by a cation-exchange membrane, an electric power supply for applying voltage between an anode and a cathode respectively provided in the anodic chamber and the cathodic chamber, a supplying path for supplying a base alkaline solution of high impurity concentration to the anodic chamber, a flow volume regulator provided at the supplying path, a circulating path for supplying the alkaline solution of high impurity concentration to the anodic chamber, a flow volume regulator provided at the supplying path, a circulating path for supplying the alkaline solution of high impurity concentration overflowed from the anodic chamber to circulate through the circulating path, a controller for controlling the flow volume regulator to increase a supplying amount of the base alkaline solution when a detected concentration value from the detector become lower than a predetermined set value and to decrease the supplying amount of the base alkaline solution when the detected concentration value becomes higher than the predetermined set value, a circulating path for circulating a refined alkaline solution overflowed from the cathodic chamber again to the cathodic chamber, a tank of the refined solution provided in the circulating path for circulating the refined alkaline solution and a means for getting out the refined alkaline solution from the tank of the refined solution and wherein a metal cation passing through the cation-exchange membrane from the anodic chamber is made to react with water of the refined alkaline solution in the cathodic chamber to obtain the refined alkaline solution of lower impurity concentration and higher concentration than the base alkaline solution.