Seek advice on the F and Cl balance in wet zinc smelting
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Our company uses conventional wet-process zinc smelting: two-stage leaching via acid leaching, three-stage purification, treatment of leaching residues in a volatilization furnace, and removal of F and Cl using multi-chamber furnaces. The zinc oxide from the lead production process is fed into the system after F and Cl have been removed; however, the levels of F and Cl in this system tend to be high. The cathode plates used in zinc electrowinning develop pitting or are difficult to separate manually. We would appreciate guidance on how to adjust the levels of F and Cl without affecting the quality of the electrolytic cathode plates:handshake
There are currently no effective methods available in China; the usual approaches include: 1. Maintaining the fluoride and chlorine levels in the system to determine the amount to be added; 2. Use of multi-chamber furnaces for removal; 3. Alkaline washing; 4. Ion exchange; 5. Removal of chlorine using copper slag; 6. Removal of fluoride using lime. Recently, rotary kilns have been used in Guangxi for chlorine removal, with very good results – up to 97% of the chlorine can be removed. There are also manufacturers that use modified roasting furnaces; it’s said to work well, but I don’t have complete information on that.
in the solution； F-200 at 300 mg/L and cL- at ≤500 mg/L are no problem; Mn should be maintained at around 7 g/L. As for the issue of pits forming on the cathode plates you mentioned, poor electrical conductivity of the plates can also cause this phenomenon. If the zinc sheets are too thin, they cannot be removed either.