What are the Electrolyzers classified by electrolyte
Electrolyzer is the electrolyte storage tank. It is the main equipment for non-ferrous hydrometallurgy. According to the applicable metal types and production processes, it is divided into copper electrolysis tank, copper electrolysis tank, zinc electrolysis tank, nickel electrolysis tank, cobalt electrolysis tank, and lead. Electrolyzer, manganese electrolyzer, copper removal tank, nickel liquid tank, etc.
According to the different electrolytes, it can be divided into: aqueous electrolytic tank, molten salt electrolytic tank, and non-aqueous electrolytic tank.
The form of aqueous electrolysis cell can be divided into two types: diaphragm electrolysis cell and non-diaphragm electrolysis cell. Diaphragm electrolyzers can be divided into homogeneous membranes, ion membranes and solid electrolyte membranes; non-diaphragm electrolyzers are further divided into mercury electrolyzers and oxidation electrolyzers. When using different electrolytes, the structure of the electrolytic cell is also different. Aqueous electrolyzers are divided into two types: diaphragm and non-diaphragm. Diaphragm electrolyzers are generally used. In the production of chlorate and the production of chlorine and caustic soda by mercury method, a diaphragmless electrolytic cell is used. Maximizing the electrode surface area per unit volume can increase the production intensity of the electrolytic cell. Therefore, the electrodes in modern diaphragm electrolyzers are mostly upright. The electrolyzer exhibits different performance and characteristics due to the material, structure, and installation of the internal components.
Molten salt electrolyzers are mostly used to produce low-melting-point metals, which are characterized by operating at high temperatures, and should try to prevent the entry of moisture to prevent hydrogen ions from being reduced on the cathode. For example, in the production of metallic sodium, since the cathode reduction potential of sodium ions is very negative, reduction is very difficult. Anhydrous molten salt or molten hydroxide containing no hydrogen ions must be used to avoid hydrogen precipitation at the cathode. For this reason, the electrolysis process needs to be carried out at a high temperature, for example, when the sodium hydroxide is electrolyzed and melted, the temperature is 310°C. When sodium chloride is contained as a mixed electrolyte, the electrolysis temperature is about 650°C. The high temperature of the electrolytic cell can be achieved by changing the electrode spacing to convert the electrical energy consumed by the ohmic voltage drop into heat energy. When electrolyzing molten sodium hydroxide, the tank body can be iron or nickel. The electrolysis of molten electrolyte containing chloride is often due to the inevitable introduction of a small amount of water in the raw material, which will cause the anode to generate moist chlorine gas, which has a strong corrosive effect on the electrolytic cell. The electrolytic cell for electrolyzing molten chloride generally uses ceramic or phosphate materials, and iron can be used for parts that are not affected by chlorine. The cathode and anode products in the molten salt electrolyzer are also required to be properly separated, and should be drawn from the bath as soon as possible to prevent the cathode product metal sodium from floating on the surface of the electrolyte for a long time, which will further interact with the anode product or oxygen in the air .
Because non-aqueous electrolyzers are often accompanied by various complex chemical reactions when preparing organic products or electrolyzing organic substances, their applications are limited and there are not many industrializations. The generally used organic electrolyte has low conductivity and low reaction speed. Therefore, a lower current density must be used, and the distance between the poles must be minimized. The electrode structure adopting a fixed bed or a fluidized bed has a larger electrode surface area, which can improve the production capacity of the electrolytic cell.