A method for recovering mixed acid from cold-rolled stainless steel pickling waste liquid

A technology of cold-rolled stainless steel and pickling waste liquid, which is applied in the field of industrial waste acid treatment, can solve the problems of increasing waste water treatment costs and low economic value, and achieve the effect of recycling waste acid

CN104498974BActive Publication Date: 2017-07-07黄健
4 Cites 0 Cited by

Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2017-07-07
Patent Text Reader

Abstract

The invention relates to a method for recycling mixed acid of nitric acid and hydrofluoric acid from cold-rolling stainless steel acid washing waste liquid. The method comprises the following steps: concentrating, carrying out a replacement reaction, separating, condensing and recycling and the like. By the aid of the method, the defects of an existing cold-rolling stainless steel acid washing waste managing technology are overcome, and the cold-rolling stainless steel acid washing waste liquid can be completely managed; no wastes and wastewater are discharged and no secondary pollution is caused; waste acid recycling and regeneration, and resource recycling are realized, so that a typical green and economic concept is sufficiently realized, and the method is an excellent method which has benefits to nation and people and is good for development of pollution treatment enterprises.
Need to check novelty before this filing date? Find Prior Art

Description

[0001]

Technical field

[0002] The invention belongs to the technical field of industrial waste acid treatment. More specifically, the present invention relates to a method for recovering mixed acid containing nitric acid and hydrofluoric acid from cold-rolled stainless steel pickling waste liquid.

[0003]

Background technique

[0004] The stainless steel cold rolling method includes the step of removing oxides by pickling, and the acid used is a mixed acid of nitric acid and hydrofluoric acid. Therefore, stainless steel pickling waste usually contains ferric nitrate, nitric acid, hydrofluoric acid, etc. Prior art usually uses the mixed acid of 8-18% nitric acid and 8-10% hydrofluoric acid, after repeatedly pickling, the metal ion in described pickling waste liquid increases to certain concentration (for example iron content reaches When about 40 grams / liter), described mixed acid loses pickling ability and becomes spent acid. At this time, the total acidity in the spe...

Examples

Embodiment 1

[0064] Embodiment 1: the present invention reclaims mixed acid from cold-rolled stainless steel pickling waste liquid

[0065] The implementation steps of this embodiment are as follows:

[0066] A. Concentration

[0067] Using a three-effect evaporation system equipped with evaporation equipment made of polytetrafluoroethylene impregnated graphite, the cold-rolled stainless steel pickling waste liquid is concentrated at a temperature of 140 ° C until the pickling waste liquid reach NO 3 - Content is 4.6% by weight, Fe ion content is 29.1% by weight, pH value≤2, obtain a kind of nitrate supersaturated concentrated waste acid, it contains other metal ions and non-metal ions below 0.40% by weight and 2.8% hydrofluoric acid, a dilute acid condensate containing 4.0% nitric acid and 3.0 hydrofluoric acid by weight is also obtained;

[0068] B. Replacement reaction

[0069] In a reactor made of polytetrafluoroethylene impregnated graphite, add concentrated sulfuric acid to the ...

Embodiment 2

[0078] Embodiment 2: the present invention reclaims mixed acid from cold-rolled stainless steel pickling waste liquid

[0079] The implementation steps of this embodiment are as follows:

[0080] A. Concentration

[0081] Using a three-effect evaporation system equipped with evaporation equipment made of polytetrafluoroethylene impregnated graphite, the cold-rolled stainless steel pickling waste liquid is concentrated at a temperature of 110°C until the pickling waste liquid reach NO 3 - Content is 4.0% by weight, Fe ion content is 37.2% by weight, pH value≤2, obtain a kind of nitrate supersaturated concentrated waste acid, it contains other metal ions and non-metal ions below 0.40% by weight and 2.0% hydrofluoric acid, a dilute acid condensate containing 6.0% nitric acid and 2.4% hydrofluoric acid by weight is also obtained;

[0082] B. Replacement reaction

[0083] In a reactor made of polytetrafluoroethylene impregnated graphite, add concentrated sulfuric acid to the n...

Embodiment 3

[0090] Embodiment 3: the present invention reclaims mixed acid from cold-rolled stainless steel pickling waste liquid

[0091] The implementation steps of this embodiment are as follows:

[0092] A. Concentration

[0093] Using a three-effect evaporation system equipped with evaporation equipment made of polytetrafluoroethylene impregnated graphite, the cold-rolled stainless steel pickling waste liquid is concentrated at a temperature of 125 ° C until the pickling waste liquid reach NO 3 - Content is 5.4% by weight, Fe ion content is 1.56% by weight, pH value≤2, obtain a kind of nitrate supersaturated concentrated spent acid, it contains other metal ions and non-metal ions below 0.40% by weight and 2.5% hydrofluoric acid, a dilute acid condensate containing 4.5% nitric acid and 2.0% hydrofluoric acid by weight is also obtained;

[0094] B. Replacement reaction

[0095] In a reactor made of polytetrafluoroethylene impregnated graphite, add concentrated sulfuric acid to the...