Electrolytic cell for removal of material from a solution

Abstract

Disclosed is an electrolytic cell for removal of material from a solution. The cell comprises a cavity for receiving the solution, a rotatable electrode located within the cavity, a counter-electrode in spaced relation to the rotatable electrode, and an ultrasonic generator coupled to said cavity for directing ultrasonic energy toward the rotatable electrode to displace solid material extracted from the solution by an electrochemical reaction. The rotatable electrode may form a cathode, and the counter-electrode may form an anode, wherein metal in the solution is deposited on the cathode as a metal powder, such that the ultrasonic energy displaces the metal powder from the cathode. Alternatively, the rotatable electrode may form an anode, and the counter-electrode may form a cathode, wherein organic waste in the solution is deposited on the anode, such that the ultrasonic energy removes the deposited organic waste from the anode.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit under 35 USC 119(e) of U.S. provisional application No. 60 / 502,950, filed Sep. 16, 2003, the contents of which are herein incorporated by reference.FIELD OF THE INVENTION [0002] The present invention relates to an electrochemical method and apparatus for treating solutions either by electrowinning or electrooxidization. BACKGROUND OF THE INVENTION [0003] The concept of recovering materials from solutions by electrolysis is not new. Many industries, such as plating processes, mining processes and metal finishing, produce waste product of solutions containing ions of metals, and recovery of this metal is both environmentally and economically beneficial. Waste from solutions with unrecovered metal increases the amount of sludge disposed on land-fields. Many systems of metal recovery currently use a mechanical device, such as a blade, to remove deposited material from an electrode. The use of a mechanical ...

AI Technical Summary

Benefits of technology

[0016] The electrolytic cell can be equipped with an hollow rotatable electrode that can be refrigerated; thus, it can be used for the electroextraction of a metal such as gallium that has a low melting point, that is present into a high temperature electrolyte such as those found in the aluminum extraction industry (bauxite processes). In such application, the gallium powder that is being produced when the rotatable electrode is polarized cathodically is recovered without using ultrasonic energy, but rather by removing the cathode from the high temperature electrolyte and dipping it into another liquid, preferably water, at a temperature above the melting temperature of gallium Hence, the powder melts down from the cathode and can be easily recovered under a solid metallic deposit when the liquid is cooled down below the melting point of gallium. The methods, equipments and chemicals used to refrigerate the hollow rotatable electrode are numerous: any combination of method, equipment and chemical that allows the refrigeration of the surface of the electrode may be applied.

[0018] There are many advantages in using this invention. First, the invention allows the recovery of metals from diluted electrolytes, more specifically from solutions where the total metal concentration ranges from 0 to 3000 ppm, preferably between 20 to 500 ppm. The invention also provides economical recovery of metals from such solutions because metals are obtained in a form of a powder which can be removed from a rotatable electrode without using a mechanical device, such as a blade, to remove it. The powdery metal deposit is easily removed from the rotatable electrode with the use of ultrasonic energy. Then the removed powder metal can be recovered using an appropriate filtration system. This separation is further simplified when the rotatable electrode is cathodic.

[0019] Third, the use of ultrasonic energy to remove deposit from the rotatable electrode cleans this latter at the same time, hence, almost eliminating the use of mineral acids or other toxic chemicals to condition its surface for further use. Fourth, the ultrasonic device of the invention can also be used to clean the surface of the rotatable electrode from organic fouling when the rotatable electrode is polarized as an anode for electrooxidation, thus avoiding complex methods for cleaning its conductive surface. However, the equipment is designed such that the rotatable electrode can be raised. Thus can be inspected, cleaned or repaired at will.

[0021] The invention is more adapted to recover metals from plating processes and mining processes, but can be applied to other types of industries such as metal finishing. The recovery of metals lowers the amount of generated waste when the apparatus is installed up-stream a wastewater system, thus, reducing the amount of sludge to dispose on land-fields.

Problems solved by technology

The applicants have found that it is not feasible to dislodge the material if it becomes deposited as a solid film.

Images