Method for removing chlorine in process of zinc electrolysis by ammonia method

Abstract

The invention belongs to the technical field of chemical treatment and relates to a method for removing chlorine in the process of zinc electrolysis by an ammonia method. The method includes: firstly,leaching is performed, wherein alkaline leaching is performed on a high-chlorine zinc-containing material with liquid ammonia; secondly, solid liquid separation is performed, wherein leachate is obtained; thirdly, purification is performed, wherein the leachate is subjected to oxidization iron removing and zinc powder replacement, and electrolytic clean liquid is obtained; fourthly, electrolysisis performed, wherein electrolytic residual liquid is obtained; and fifthly, chlorine removal is performed, wherein when the concentration of chlorine ions in the electrolytic residual liquid is between 180g / L and 280g / L, the electrolytic residual liquid is used for the leaching work procedure; and when the concentration exceeds 280g / L, part of the electrolytic residual liquid is used for the leaching work procedure, and the other part is subjected to standing cooling in a cooling pond, and clean liquid flows back to an electrolysis work procedure to be used. By using the method, the concentration of chlorine ions in electrolyte is effectively reduced, the current efficiency in the electrolysis process is improved, and it is guaranteed that production is continuously performed; and meanwhile, the precipitation speed of ammonium chloride is increased through the cooling pond, and the method is safe, capable of saving energy, easy to operate, small in investment, environment-friendly andfree of emission.

Description

technical field [0001] The invention belongs to the technical field of chemical treatment, and relates to a method for removing chlorine in an ammonia-based electrolytic zinc process. Background technique [0002] Since the chlorine content of the acid electrolyte in the electrolytic zinc process needs to be less than 0.2g / L, the chlorine element becomes a harmful element in the traditional acid electrolytic zinc process, resulting in that high-chlorine zinc-containing materials cannot be preferentially selected and used; at the same time, high-chlorine The cost of chlorine removal for zinc-containing materials is also high, mainly due to: low efficiency of chlorine removal by heating and roasting in the furnace or rotary kiln; lengthy process of alkali washing method, large loss of zinc, high treatment cost, and difficulty in sewage treatment; hardware investment in ion exchange method Large size and high cost of consumables; therefore, the ammonia-based electrolytic zinc w...

AI Technical Summary

Problems solved by technology

[0002] Since the chlorine content of the acid electrolyte in the electrolytic zinc process needs to be less than 0.2g / L, the chlorine element becomes a harmful element in the traditional acid electrolytic zinc process, resulting in that high-chlorine zinc-containing materials cannot be preferentially selected and used; at the same time, high-chlorine The cost of chlorine removal for zinc-containing materials is also high, mainly due to: low efficiency of chlorine removal by heating and roasting in the furnace or rotary kiln; lengthy process of alkali washing method, large loss of zinc, high treatment cost, and difficulty in sewage treatment; hardware investment in ion exchange method Large size and high cost of consumables; therefore, the ammonia-based electrolytic zinc with obvious advantages has been widely concerned and scrambled to be developed by electrolytic zinc companies. The advantages of low environmental pressure and low price

[0003] Although ammonia-based electrolytic zinc has the above-mentioned advantages, there are very few manufacturers that have actually put into industrialized and mass-produced production, and the enterprises that have already put into production also have many problems such as temperature control, additive selection, chlorine crystallization pipe plugging, etc., and cannot realize continuous production.

Among them, chlorine crystal plugging is the main problem affecting production, mainly because during long-term use, the concentration of chloride ions will gradually increase and reach saturation, and after supersaturation, it will be crystallized in the form of ammonium chloride, resulting in Difficulty in leaching hydraulic filtration, blockage of electrolyte pipelines, reduction of electrolysis current efficiency, etc.; at the same time, many ammonia process literatures only mention that high-chlorine zinc-containing materials can be used, but the limit and exceeding the concentration of chloride ions in the electrolyte How to remove chlorine after the limit is not detailed, which seriously affects the continuous process of ammonia electrolytic zinc process

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