Technology for treating stainless steel nitrate-free pickling waste water

Abstract

The invention relates to a technology for treating stainless steel nitrate-free pickling waste water. The technology comprises the following steps: respectively leading the pickling waste water and neutral salt waste water into corresponding adjusting tanks; adjusting the pH value of the neutral salt waste water and reducing hexavalent chrome; leading the reduced neutral salt waste water and the pickling waste water into a neutralizing tank together, and neutralizing the waste water by using caustic soda liquid; after carrying out aeration treatment on the neutralized waste water, carrying out solid-liquid separation by using a superfine separator, concentrating and dehydrating sludge obtained by separation to form heavy metal mud, leading the waste water obtained by separation into a defluorination reaction tank, and carrying out fluorine removal treatment; and continuing leading the waste water subjected to the fluorine removal treatment to a settling pond for mud-water separation to obtain fluoride mud and supernatant which conforms to the emission standard. Compared with the prior art, the technology has the advantages that the waste water treated by the technology reaches requirements of a chart 2 of GB13456-2012, the heavy metal mud and the fluoride mud are obtained step by step, wherein the heavy metal mud has re-melting and reusing value, and the fluoride mud which is lower than the requirements of the standard of GB5085.3-2007 can be treated as common solid wastes after being identified.

Description

technical field [0001] The invention relates to the field of industrial wastewater treatment, in particular to a stainless steel nitric acid-free pickling wastewater treatment process. Background technique [0002] Due to its exquisite appearance, high strength and light weight, stainless steel is widely used in petroleum, chemical, machinery, construction and other fields. At present, the main factor restricting the development of the stainless steel industry is the pickling wastewater produced in the production process. The pickling wastewater has high acidity (4-7mol / L), strong toxicity (containing nickel, chromium, fluorine and other toxic pollutants), high Large and difficult to handle. GB13456-2012 "Water Wastewater Discharge Standard for Iron and Steel Industry" has added the requirements for the total nitrogen index in pickling wastewater. The national standard stipulates that the total nitrogen in pickling wastewater shall not exceed 15mg / L. Currently, the neutrali...

AI Technical Summary

Problems solved by technology

When the traditional treatment method of lime neutralization is used to treat the pickling wastewater of this process, although the wastewater can be discharged up to the standard after lime neutralization, a large amount of sludge is formed at the same time, and the sludge composition is complex and cannot be recycled directly. Disposal of hazardous waste not only entails huge disposal costs but also causes waste of resources

In addition, the traditional lime neutralization treatment process still has the following problems: serious scaling and clogging of pipes, reaction tanks and other structures, and poor operation; the calcium sulfate content in the sludge produced by wastewater treatment has a large proportion, resulting in difficult dehydration , the filter cloth filter plate of the filter press is seriously scaled; the amount of sludge is increased by more than 30% compared with the wastewater treatment process of nitric acid pickling treatment process, etc.

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