Waste acid liquid regeneration pretreatment method and system

Abstract

The invention discloses a waste acid liquid regeneration pretreatment method. The method comprises the following steps: waste acid liquid filtering: filtering waste acid liquid discharged from a pickling tank of a pickling line; adsorbing free acid in the waste acid liquid: filtering the liquid to obtain solid particles, conveying the solid particles to a resin bed, and adsorbing the free acid inthe waste acid liquid; desorpting free acid in the waste acid liquid: desorbing the free acid adsorbed by the resin bed, and conveying the desorbed free acid back to a pickling line for reuse; and enabling the rest waste liquid containing metal ions into an acid regeneration system for complete regeneration and recovery treatment. The invention further discloses a waste acid liquid regeneration pretreatment system. The method and system have the beneficial effects that the method and system are used for pretreatment of the spray roasting process, online acid purification can be achieved, freeacid is recycled in real time, consumption of nitric acid and hydrofluoric acid is reduced, metal salt is removed, formation of sludge in an acid tank is reduced, the dredging period of an emptying acid tank is greatly prolonged, and the production efficiency of a unit is improved.

Description

technical field [0001] The invention relates to the technical field of waste acid treatment, in particular to a waste acid regeneration pretreatment method and system. Background technique [0002] In steel production, the surface of stainless steel is usually treated by pickling with mixed acid (nitric acid + hydrofluoric acid). The waste acid produced after pickling by this pickling method is extremely corrosive, and if not treated, it will cause serious pollution to the environment; at the same time, due to the large amount of waste acid discharge, it will also cause waste of resources, thereby improving pickling. cost. [0003] At present, in the treatment of stainless steel pickling waste acid, the spray roasting process is the most advanced regeneration process, which can completely regenerate the waste acid. In the waste acid regeneration process based on the spray roasting method, the waste acid undergoes a chemical reaction to produce free HF and HNO 3 , after be...

AI Technical Summary

Problems solved by technology

[0004] The spray roasting process can recover more than 90% of hydrofluoric acid, but can only recover about 40-60% of nitric acid. Most of the nitric acid in the waste acid solution is decomposed into NO which is not easily absorbed under high temperature roasting. x (nitrogen oxides NO 2 , NO abbreviation) gas, and a large amount of NO x The gas will lead to expensive denitrification treatment costs; at the same time, the process, together with unnecessary free nitric acid, hydrofluoric acid and water, consumes a lot of energy, which brings great pressure to today's rising energy costs

Images