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Regeneration method of acid washing waste acids

A technology for pickling waste acid and nitric acid, which is applied in the field of recovering iron salts and acids from pickling waste acid, can solve the problems of low recovery rate and high follow-up treatment costs, and achieve low input costs, saving treatment costs and operating costs low effect

Active Publication Date: 2015-06-17
NANTONG CHENGGUANG GRAPHITE EQUIP
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  • Abstract
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  • Claims
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AI Technical Summary

Problems solved by technology

[0006] In a nutshell: "spray recovery process" and "sulfuric acid replacement process" are full acid recovery processes, basically no secondary pollution treatment problems, while "ion exchange process" is a free acid recovery process, not only low recovery rate but also waste water treatment and heavy metals Processing and other follow-up processing costs are more

Method used

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  • Regeneration method of acid washing waste acids

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] refer to figure 1 As shown, the pickling waste acid sent from the pickling waste acid workshop mainly contains hydrofluoric acid, nitric acid and iron salts, and the regeneration method of pickling waste acid comprises the following steps:

[0037] Step 1): Filtration by pumping to filter out dirt and impurities;

[0038] Step 2): The filtered and purified pickling waste acid is transported by the system pipeline to the YKZ type round hole graphite heat exchanger, and preheated at 75°C. After preheating, part of the hydrofluoric acid and nitric acid are evaporated;

[0039] Step 3): Send the preheated remaining waste acid to the III-effect evaporator for flash evaporation at 85°C to obtain the mixed steam of hydrofluoric acid and nitric acid, the mixed liquid of saturated iron salt, hydrofluoric acid and nitric acid, The Ⅲ effect evaporator is a falling film bidirectional anti-corrosion evaporator, the tube side is F4 impregnated graphite, and the shell side is steel-l...

Embodiment 2

[0046] The pickling waste acid sent from the pickling waste acid workshop mainly contains hydrofluoric acid, nitric acid and iron salt, and the regeneration method of pickling waste acid includes the following steps:

[0047] Step 1): Filtration by pumping to filter out dirt and impurities;

[0048] Step 2): The filtered and purified pickling waste acid is transported by the system pipeline to the YKZ type round hole graphite heat exchanger, and preheated at 85°C. After preheating, part of the hydrofluoric acid and nitric acid are evaporated;

[0049] Step 3): Send the preheated remaining waste acid to the III-effect evaporator for flash evaporation at 85°C to obtain the mixed steam of hydrofluoric acid and nitric acid, the mixed liquid of saturated iron salt, hydrofluoric acid and nitric acid, The Ⅲ effect evaporator is a falling film bidirectional anti-corrosion evaporator, the tube side is F4 impregnated graphite, and the shell side is steel-lined ETFE;

[0050] Step 4): T...

Embodiment 3

[0056] The pickling waste acid sent from the pickling waste acid workshop mainly contains hydrofluoric acid, nitric acid and iron salt, and the regeneration method of pickling waste acid includes the following steps:

[0057] Step 1): Filtration by pumping to filter out dirt and impurities;

[0058] Step 2): The filtered and purified pickling waste acid is transported by the system pipeline to the YKZ type round hole graphite heat exchanger, and preheated at 80°C. After preheating, part of the hydrofluoric acid and nitric acid are evaporated;

[0059] Step 3): Send the preheated remaining waste acid to the III-effect evaporator for flash evaporation at 85°C to obtain the mixed steam of hydrofluoric acid and nitric acid, the mixed liquid of saturated iron salt, hydrofluoric acid and nitric acid, The Ⅲ effect evaporator is a falling film bidirectional anti-corrosion evaporator, the tube side is F4 impregnated graphite, and the shell side is steel-lined ETFE;

[0060] Step 4): T...

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Abstract

The invention discloses a regeneration method of acid washing waste acids, which comprises the following steps: carrying out waste acid early-stage concentration by a triple-effect evaporation technique to evaporate out saturated iron salts from the substance containing hydrofluoric acid, nitric acid and iron salts, replacing the iron salts with sulfuric acid, volatilizing and separating nitric acid and hydrofluoric acid out of the acid mixture by heating assisted by decompression, and condensing the volatilized acid mist and water vapor, thereby obtaining abundant nitric acid and hydrofluoric acid which are used for acid washing.

Description

technical field [0001] The invention relates to a method for recovering industrial pickling waste acid, in particular to a method for recovering iron salt and acid from pickling waste acid. Background technique [0002] At present, the recovery and utilization of nitric acid-hydrofluoric acid mixed pickling waste resources are mainly the following three methods that are more mature at this stage: [0003] a. Spray roasting process: Hydrofluoric acid, nitric acid and stainless steel metal oxide powder are recovered by pyrolysis method. The spray roasting process has the characteristics of good environmental protection effect and high economic value. The recycled mixed acid can be recycled, and metal oxides can be used as raw materials for stainless steel powder metallurgy or steelmaking. However, due to its high cost and only relying on imported equipment, few domestic customers currently use it. [0004] b. Sulfuric acid replacement process: Use low-value sulfuric acid to r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23G1/36
CPCC23G1/36
Inventor 黄健陈萍张月圆黄垭楹
Owner NANTONG CHENGGUANG GRAPHITE EQUIP
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