Resource recycling method of stainless steel pickling wastewater

Abstract

The invention relates to a resource recycling method of stainless steel pickling wastewater. The resource recycling method comprises the following steps: concentrated nitric acid is added to the stainless steel pickling wastewater, and pH is regulated to 1.5-2.5; the wastewater is filtered, and iron and chromium precipitates are obtained; the stainless steel pickling wastewater is concentrated, concentrated acid water is obtained and subjected to reduced-pressure evaporation, an evaporated liquid is collected, and hydrofluoric acid and nitric acid are obtained; the solution after hydrofluoric acid and nitric acid are separated is cooled and filtered, and iron is recovered from the solution; a preneutralization agent is added to the solution obtained after acid recovery to control pH, and sedimentation and filtering are performed; a vulcanizing agent is added to a filtrate after acid removal through neutralization, vulcanizing pH is controlled, nickel-chromium separation is completed with a vulcanizing method, and nickel recovery is realized. Compared with the prior art, nickel ions can be extracted from waste liquor, and wastewater recovery can be realized without introduction of new impurities.

Description

technical field [0001] The invention relates to a resource recovery method of stainless steel pickling wastewater. Background technique [0002] Stainless steel is known as a fine steel product. With its superior corrosion resistance, unique surface and excellent processing performance, it has developed very rapidly and its application fields have become wider and wider. The pickling of stainless steel strip is a key process in the production of cold-rolled stainless steel, which plays a decisive role in ensuring the surface quality of the product. The pickling process has also developed from pure chemical pickling in the 1960s and 1970s to the current combination of chemical pickling and electrolytic pickling. Wastewater containing heavy metals nickel and chromium will be produced in stainless steel pickling. Traditionally, these wastewaters are discharged directly, seriously polluting the environment. [0003] Stainless steel slag contains a large amount of valuable met...

AI Technical Summary

Problems solved by technology

In addition, stainless steel slag contains Cr 6+ Toxic compounds, if not treated, the tailings discharged will also cause serious harm to the surrounding environment, destroy the structure of soil vegetation, pollute the air and water