Method for recycling and processing waste liquid produced by combined desulfurization and denitrification technology using steel slag as absorbent

Abstract

The invention provides a method for recycling and processing a waste liquid produced by a combined desulfurization and denitrification technology using steel slag as an absorbent. Firstly, solid-liquid separation is conducted on the waste liquid which absorbs SO2 and NOx and reaches a total salt concentration; then, after the separation, quick lime and / or slaked lime are / is added into the obtained liquid phase to adjust pH, and after filtration, the pH of the filtrate is adjusted to 5-7; the filtrate is introduced into a micro-nano bubble generator, nitrite in the filtrate is completely oxidized to nitrate, and by subsequent operations such as evaporation, concentration, crystallization, filtration, desiccation and the like, calcium nitrate products are obtained. The method is a subsequent process of a metallurgy-slug combined desulfurization and denitrification technology, and solves the problem that secondary pollution is caused by the waste liquid which is produced by the metallurgy-slug combined desulfurization and denitrification technology, the nitrite is completely converted into the nitrate, the complete utilization of the N element in the waste liquid is achieved, and the pure calcium nitrate products are obtained. Meanwhile, the calcium nitrate products reach national standards of industrial calcium nitrate and agricultural calcium nitrate, and have good application prospects.

Description

technical field [0001] The invention relates to the fields of environmental protection and waste water recycling, in particular to a method for recycling and treating waste liquid produced by using steel slag as an absorbent combined with a desulfurization and denitrification process. Background technique [0002] In recent years, with the improvement of my country's industrialization level and rapid economic growth, air pollution has become increasingly serious. SO 2 and NO x emissions are increasing. Domestic for containing SO 2 and NO x The gas needs to be treated and discharged up to standard. [0003] In the desulfurization and denitrification methods disclosed in the prior art, the process involving ammonia has problems such as long process, ammonia leakage, and the need for catalysts; while the dry desulfurization and denitrification cost is high and the removal rate is low; the use of nano-scale materials for desulfurization and denitrification, There are proble...

AI Technical Summary

Problems solved by technology

[0005] However, this treatment process will produce a large amount of desulfurization and denitrification waste liquid. Due to the complex composition of metallurgical slag, there are many types of anions and cations in the combined desulfurization and denitrification waste liquid, and it also contains NO 3 - , NO 2 - , SO 4 2- , SO 3 2- 、HSO 4 - 、HSO 3 - Isoanions and Mg 2+ , Ca 2+ , Mn 2+ or Fe 3+ Cationic, difficult to handle

And the NO 3 - and NO 2 - mixed together, and NO 2 - It is difficult to be completely oxidized, so it is difficult to obtain pure nitrate products when the waste liquid is subsequently recycled