Method for direct electrolytic refining of crude lead

Abstract

The invention relates to a method for direct electrolytic refining of crude lead, and belongs to the technical field of lead refining. According to the method, the crude lead prepared by pyrometallurgy is casted into a crude lead anode, wherein the crude lead anode is sleeved inside an anode bag; and electrolysis is performed in an additive-containing perchloric acid-lead perchlorate solution electrolyte to electrically deposit the lead in the anode on the cathode, such that the high purity electrolyzed lead and the anode mud are respectively obtained from the cathode and the anode. With the present invention, the lead without a pre-refining treatment can be directly subjected to electrolytic refining to obtain the pure lead with the purity more than 99.99% and the anode mud doped with noble metals, such that the recovery rate of the noble metals can be substantially improved so as to provide greater economic benefits.

Description

technical field [0001] The invention belongs to the technical field of lead refining, and relates to a direct electrolysis method of crude lead, specifically, the crude lead obtained by the existing pyrometallurgy process is directly electrolytically refined by an electrochemical method to obtain high-purity electrolytic lead and Method for residual valuable metals. Background technique [0002] With the rapid development of automobiles and other vehicles, lead-acid batteries, as an indispensable chemical power source for these vehicles, have also developed rapidly. According to statistics, my country's lead output in 2010 reached more than 3.5 million tons, of which nearly 80% of the lead was used in the field of lead-acid battery manufacturing. In order to reduce the self-discharge coefficient of the battery, the valve-regulated maintenance-free lead-acid battery puts forward high requirements on the impurity content of the lead raw material. Generally, in order to ensur...

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Problems solved by technology

[0005] 2. Fluorosilicic acid is easy to volatilize and decompose into toxic HF and SiF when heated 4 , the process generally can only use dilute fluorosilicic acid solution, and the electrolysis temperature is generally controlled at a relatively low temperature (30-45°C), this relatively dilute electrolyte and low working temperature make the conductivity of the electrolyte The rate is low, and the ion diffusion speed is slow, so the current density that the electrolysis process can withstand is also low, generally 180-200A / m 2 , and at the same time, a cell voltage of up to 0.4-0.5V is generated during the electrolysis process, making the electrolysis energy consumption per ton of lead up to 120-135KWh

[0006] 3. The toxicity of fluorosilicate-lead fluorosilicate solution is relatively high, and the solution itself is easy to volatilize, which is more prominent when working in summer. The fluorosilicate volatilized from the electrolytic cell and the toxic products produced by its decomposition SiF 4 And HF gas not only smells bad, but also directly endangers the health of operating staff

We found in our research that it is difficult to achieve complete anodic dissolution with this simple shape anode. The main reasons are that firstly, the anode area is small and it is difficult to bear high current density; With the gradual enrichment of anode slime on the surface, the impedance of the electrolysis process continues to increase. Often when only 50% of the anode remains, the electrolysis is terminated early due to the large amount of anode slime on the surface

The third is that due to the incomplete flatness of the cathode electrodeposited lead surface, the electrode spacing between the flat anode and the lead cathode gradually shortens as the electrolysis progresses, so people have to reserve a 4-5cm electrode spacing in advance to prevent The short circuit between the electrodes, this long distance between electrodes aggravates the rise of electrolysis energy consumption

In addition, the anode stripping potential of metal copper in crude lead is higher than that of metal lead, but it is easily dissolved in the electrolyte under the oxidation of oxygen in the air, and the dissolved trace copper is easily accompanied by the cathode due to the high electrode potential. The lead electrodeposition process leads to the high index of copper in electrodeposited lead, which has to prompt people to also use the fire pre-refining process to greatly reduce the content of copper, tin and other impurities in crude lead. Some electrolytic refining provides high-quality raw materials

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