Multi-level recycling system and method for acid-making wastewater of smelting flue gas

Abstract

The invention discloses a multi-level circulation recycling system and method for the acid-making wastewater of smelting flue gas, and belongs to the technical field of chemical engineering. The method includes the steps of using the concentration gradient formed in the process of acid crossflow from back to front when purifying acid wastewater, the deposition of smoke dust in acid wastewater, andthe concentration of fluorine, acid and chlorine, and forming the multi-level circulation concentration recycling system for purifying the acid wastewater; using a cooling tower as a purification watershed, and ensuring that impurities in the flue gas cannot affect the follow-up safe and stable operation of the system; using coarse filtration and fine filtration to remove mud from the acid wastewater, which solves the problem of high solid content in the purifying recycling acid wastewater and improves the recycling rate of the acid wastewater; besides, using multi-level atomization humidifying, dissolving hydrogen fluoride gas in the flue gas, and through condensation and electrostatic-demister, effectively avoiding the risk that hydrogen fluoride enters the post drying and conversion processes. The system and the method have the advantages of low investment, reliable running, simple operation and a remarkable acid wastewater concentration recycling effect, and achieves the purposesof energy saving, emission reduction and cleaner production.

Description

technical field [0001] The invention belongs to the technical field of chemical industry and relates to wastewater treatment in nonferrous metal smelting, in particular to a multi-level recycling system and method for waste water from smelting flue gas acid production. Background technique [0002] A large amount of acidic wastewater will be produced during the wet purification and washing process of acid production from non-ferrous metal smelting flue gas. The existing purification process is single, and the dust and lead that restrict the purification process have not been effectively treated, resulting in a large amount of acid water discharge, The reuse rate is low. However, if the acid water is forced to circulate and concentrate inside the purification system, firstly, the dust in the flue gas will cause serious acid mud deposition in each purification tower, block the spray device and the packing in the tower, and then reduce the effect of washing and dust removal, wh...

AI Technical Summary

Problems solved by technology

[0002] A large amount of acidic wastewater will be produced during the wet purification and washing process of acid production from non-ferrous metal smelting flue gas. The existing purification process is single, and the dust and lead that restrict the purification process have not been effectively treated, resulting in a large amount of acid water discharge, Low reuse rate

However, if the acid water is forced to circulate and concentrate inside the purification system, firstly, the dust in the flue gas will cause serious acid mud deposition in each purification tower, block the spray device and the packing in the tower, and then reduce the effect of washing and dust removal, which is not conducive to the back-end acid production The stability of the system; secondly, the dust and sludge in the system continue to circulate and enrich, and the lead content increases, and then enters the interior of the electrostatic demister, which will cause the cathode line and the anode tube to accumulate lead, reduce the demisting efficiency, and pose a safety hazard; In addition, because the smelting flue gas contains a large amount of harmful impurities, especially gaseous impurities such as some fine-grained metal oxide dust, hydrogen fluoride, and sulfur trioxide, it is more harmful to the subsequent acid production system, and the acid water is forced to circulate in the original purification system. , there is bound to be an increase in the concentration of various impurities due to the concentration of acid water, especially the enrichment of hydrogen fluoride is more harmful to the drying tower and subsequent equipment, which is not conducive to the stability and safe production of the rear-end acid production system

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