| In recent years the zinc production in our country has been close to 6 million tons per year,80% of which is produced by zinc hydrometallurgy technology.Zinc sulfate solution electric is an important process of the zinc hydrometallurgy technology.When zinc electrolyzing, the fluorine ion and chlorine ion existed in the electrolyte and the acid fog in the production workshop could easily to make the plate corrode,which has a great influence to the production, cost and quality.The corrosion phenomena is more serious than before in the company of zinc production in Shanluo Shaanxi because of the complicated sources of the raw material,so plate corrosion prevention and increase its working lifet are the problems that urgent to be solved.Based on the research methods of the principle of corrosion electrochemistry,application of electrochemical and corrosion experiment simulated,in this paper,the corrosion performance in the sulfate solution was studyed on the cathode plate and anode plate and the corrosion mechanism of the fluoride ion and chloride ion to plate in the electrolyte is studyed.it also analyzed the feasibility of the engineering measures to reduce plate corrosion based on the analysis of the literature and the production from the plate material, purification technology and workshop ventilation.it could provide theoretical basis for the production practice.The related research content is as follows:(1)Corrosion experiment simulated:the paper text the degree of corrosion with the conditions of the single factor and mixed factors.The results show that with the increasingly concentration of the fluoride ion and chloride ion in the electrolyte,the corrosion degree of thecathode plate is on the rise.When the Cl- concentration is less than 600mg/L,there is almost no concentration in the cathode plate,when the Cl- concentration is between 600mg/L and1000mg/L,the cathode plate all can be corroded to some degree,When the Cl- concentration is more than 1000mg/L,the concentration in the cathode plate is obvious increase.The cathode plate and anode plate are all no corroded when there is only F- in the electrolyte.The cathode plate corrosion degree is more serious when the fluoride ion and chloride ion are all in the electrolyte than either.The corrosion effect of the chloride ion is bigger than the fluoride ion.In the process of the fluoride ion and chloride ion concentration become larger,there is no obvious corrosion phenomena on the anode plate.(2)The XRD analysis results show that the anodic corrosion product is mainly about the plumbous oxide except for a little Pb SO4.The cathodic corrosion products are mainly Zn SO4 and Na Al(SO4)2.(3)The analysis of the polarization curve indicate that the fluoride ion and chloride ion in the electrolyte are all show depolarization effect.Hydrogen precipitation is increasing when the Chloride ion concentration increased,but it has little change when Fluorine ion concentration increased.The analysis of cyclic voltammograms curve shows that Chloride ion made the reduction potential rise of the the cathode product and the precipitation of reduction isrestrained when there is Fluorine ion in the electrolyte.The analysis of Ac impedance diagram show that Zinc deposits will becomes difficult with the concentration of fluoride ion and chloride ion is increasing.(4)According to the ventilation mode used in electrolytic workshop,the relation between the speed of air exhaust and the influence degree of plate corrosion was studyed for two different operating conditions(ventilate in negative pressure on the bottom of the closed workshop and forced ventilation at the top of the open workshop) by the experiment.The results showed that under the condition that the fluorine ion and chlorine ion is same in the electrolyte,the corrosion degree of the plate in closed workplace has a obvious downward trend with the increase of speed of air exhaust and is stable in the outdoor environment,which loss rate is about 11%.When the speed of air exhaust is less than 130m3/min,the plate loss rate is higher in the closed environment but is lower when the speed of air exhaust is higher than130m3/min.(5)Under the same experimental conditions,the new lead dioxide anode, quaternary alloyanode and binary alloy anode were used for anode plate and their performance for corrosion resistant was contrasted by experiment.The result shows that lead dioxide anode is better and second is quaternary alloy anode, binary alloy anode is the worst.(6) According to current situation of the production of Shaanxi Xin Ye, appropriate measures taken are: using the copper slag dechlorination method to reduce the content of chlorine ion in the electrolyte; Strictly control the plate quality;Use moderate additives can reduce acid fog or increasing the speed of air exhaust timely; use the new lead dioxide anode for small-scale industrial test. |
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