Research On Operation And Optimization Of Cobalt Electro-Deposition Process By Ion Exchange Membrane Method

Cobalt is an iron group metal element, because of its simple substance has good physical and chemical properties and machining performance, cobalt is widely used in aerospace,machinery processing, chemical industry, electronics industry and health and other fields, it is also an extremely important strategic resource. Chinese cobalt resources are poor and mainly existed in iron, nickel, and copper mineral deposits. For a long time, cobalt smelting company mainly produces chemical form of cobalt salts and cobalt oxide, with the continuous development of the aviation industry and modern machinery industry, the metal cobalt refining production has become particularly important. This paper analyzes the status quo of cobalt metal refining production process, most domestic and foreign production enterprises are using the insoluble anode electrolytic method. In view of the presence of chlorine pollution problems, the paper proposes a new method of membrane electrodeposition production process and an electrodeposition process equipment(double-membrane three-room membrane module), in order to promotes the technology innovation of cobalt refining industry.This paper research on membrane electrolysis process specifications(including the electrolyte temperature, current density, electrode spacing, circulation flow rate, and fill medium, etc) by conducting single factor and orthogonal experiment study with self-made double-membrane three-compartment membrane module. Obtained that it is feasible using membrane electrodeposition technology for refining production of cobalt metal, the influence level of each factors are as follows: current density> electrolyte temperature> pole spacing>circulation flow rate> sulfuric acid concentration. Cobalt chloride as the electrolyte(at a concentration of 110±5g/L, circulation flow rate of 3L/h), 1% dilute sulfuric acid and 0.5%dilute hydrochloric acid as the fill medium, under the conditions of 45℃ electrical fluid temperature, 200A/m2 current density, 100 mm pole spacing, the test result is satisfactory. The current efficiency of membrane electrodeposition process has reached 97.91%, and the cathode board laminated flat, densified and smooth without pinhole and nodulation phenomenon.Considering the amplification effect and industrial applications problems, paper conducted pilotscale experiment on the basis of preliminary experiment. Two stage pilotscale experiments showed that: average current efficiency of the membrane electrodeposition process reached 90.71%. Compared with conventional electrodeposition process, the current efficiency increased by about 2.2 percentage points and the chlorine production reduced amount 93.8%. After the deaeration and absorption by alkali, chlorine system-wide reduction amounted to 99.11%. Per tonne cost of cobalt production savings about 5448.92 yuan, which is a significant economic and environmental benefits.Laboratory test and pilotscale experiments result that: it is feasible that using membraneelectrodeposition technology for refining production of metal cobalt, the technology is expected to achieve scale and industrial applications through improving membrane module structure, developing high-performance ion exchange membrane, improving the effect of circulation system. Thus promoting technological innovation of the cobalt refining industry.