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A method for recycling fluorine-containing nitric acid

A technology of fluoronitric acid and nitric acid, which is applied in the field of waste recycling, can solve the problems of high risk factor, high requirements, and short membrane life of hydrofluoric acid, and achieve good economic and environmental benefits

Active Publication Date: 2022-04-12
盛隆资源再生(无锡)有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The above-mentioned three kinds of waste acid treatment processes all have big problems in terms of investment, operation cost, environmental protection, secondary pollution, and safety: (1) neutralization method for industrial waste acid, a large amount of free acid with economic value and Metal salts have not been utilized at all, and a large amount of alkaline substances are added to neutralize, resulting in several times the volume of filter residues, causing secondary pollution to the environment; (2) waste acid concentration method to treat waste acid, to solve the pollution and pollution of industrial waste acid Reuse plays a positive role, but the construction investment of this device is huge, and the operating cost and cost are high. At the same time, because industrial waste acid is mixed with a large amount of metal salts, it consumes heat in the concentrated environment, crystallizes and blocks the heat exchange device, resulting in the concentration of the concentration device. Difficult to operate; (3) Diffusion dialysis membrane method has reasons such as small processing capacity, short membrane life, easy aging and damage, and low cost performance, which limit its industrial production and use
Although this method is feasible in production, the composition of the fluorine-removing particles used is complex, and the synthesized potassium fluorosilicate solution is not single; the particles after fluorine fixation are small, and flocculants need to be used for flocculation and sedimentation, and the steps are complicated; when using hydrofluoric acid When preparing calcium fluoride and potassium fluorosilicate, the requirements for equipment are high, and the reaction tank of fluorine-resistant materials must be selected, and the raw material hydrofluoric acid used has a high risk factor

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  • A method for recycling fluorine-containing nitric acid

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Effect test

Embodiment 1

[0057] This embodiment provides a method for recycling fluorine-containing nitric acid, the process flow diagram of the method is as follows figure 1 shown, including the following steps:

[0058] (1) Mix defluorinating agent and fluorine-containing nitric acid, carry out solid-liquid separation after fully reacting, obtain sodium fluorosilicate and low-fluorine nitric acid; Described fluorine-removing agent comprises silicon dioxide and sodium nitrate; In the described fluorine-containing nitric acid, H + Concentration is 6.85mol / L, is made up of the nitric acid of 32wt%, the hydrofluoric acid of 2.5wt% and the acetic acid of 3wt%, the balance is water; The mol ratio is 0.9:1, and the mol ratio of the addition of sodium nitrate in the defluoridation agent to hydrofluoric acid in the fluorine-containing nitric acid is 1.05:1;

[0059] (2) mix calcium carbonate and step (1) gained low-fluorine nitric acid, carry out solid-liquid separation after fully reacting, obtain calcium ...

Embodiment 2

[0067] The present embodiment provides a kind of method that fluorine-containing nitric acid recycles, and described method comprises the steps:

[0068] (1) Mix defluorinating agent and fluorine-containing nitric acid, carry out solid-liquid separation after fully reacting, obtain potassium fluorosilicate and low-fluorine nitric acid; Described defluorinating agent comprises silicon dioxide and potassium nitrate; H in described fluorine-containing nitric acid + Concentration is 5.53mol / L, is made up of the nitric acid of 28wt%, the hydrofluoric acid of 1.5wt% and the acetic acid of 2wt%, balance is water; The mol ratio is 0.9:1, and the mol ratio of the addition of potassium nitrate in the defluoridation agent to hydrofluoric acid in the fluorine-containing nitric acid is 1.05:1;

[0069] (2) mix calcium nitrate and step (1) gained low-fluorine nitric acid, carry out solid-liquid separation after fully reacting, obtain calcium fluoride and defluoridation nitric acid; The add-...

Embodiment 3

[0077] The present embodiment provides a kind of method that fluorine-containing nitric acid recycles, and described method comprises the steps:

[0078] (1) Mix defluorinating agent and fluorine-containing nitric acid, carry out solid-liquid separation after fully reacting, obtain potassium fluorosilicate and low-fluorine nitric acid; Described defluorinating agent comprises silicon dioxide and potassium nitrate; H in described fluorine-containing nitric acid + Concentration is 8.13mol / L, is made up of the nitric acid of 36wt%, the hydrofluoric acid of 3.5wt% and the acetic acid of 4wt%, balance is water; The mol ratio is 0.9:1, and the mol ratio of the addition of potassium nitrate in the defluoridation agent to hydrofluoric acid in the fluorine-containing nitric acid is 1.05:1;

[0079] (2) mix calcium oxide and step (1) gained low-fluorine nitric acid, carry out solid-liquid separation after fully reacting, obtain calcium fluoride and defluoridation nitric acid; The add-on...

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Abstract

The invention provides a method for recycling fluorine-containing nitric acid. The method comprises the following steps: mixing a fluoride-removing agent and fluorine-containing nitric acid, and performing solid-liquid separation after sufficient reaction to obtain fluorosilicate and low-fluorine nitric acid; mixing calcium Salt and low-fluorine nitric acid, after fully reacting, carry out solid-liquid separation to obtain calcium fluoride and fluorine-removing nitric acid; mix masking agent, catalyst and fluorine-removing nitric acid, heat until the reaction is complete, and obtain decarburization liquid and nitrogen-containing gas; concentrate decarburization liquid to obtain nitric acid and the remaining mother liquor; neutralize the remaining mother liquor, concentrate the liquid obtained after neutralization, and reuse the obtained nitrate as a defluoridation agent. The method provided by the invention can realize the recycling of fluorine-containing nitric acid containing nitric acid, hydrofluoric acid and acetic acid, and can obtain higher-purity fluorosilicate, calcium fluoride, nitric acid and aluminum sulfate, and the recycling process produces Gas and salt can be fully utilized, achieving a good combination of economic and environmental benefits.

Description

technical field [0001] The invention belongs to the technical field of waste recycling and relates to a method for recycling waste acid, in particular to a method for recycling fluorine-containing nitric acid. Background technique [0002] A large amount of fluorine-containing nitric acid is produced in the production of photovoltaic solar cells and semiconductor wafers. The main hazards in waste acid are fluorine ions and total nitrogen, and direct discharge will cause serious harm to the environment. [0003] At present, the relatively mature treatment processes for industrial waste acid include: (1) Neutralization method: add the waste acid solution to alkaline substances for acid-base neutralization, adjust the pH of the neutralized liquid to 6-9, and air can be introduced if necessary Perform forced aeration to improve the coagulation speed and structure of the neutralized sediment. After neutralization, the slurry is separated from solid and liquid, the filter residue ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B21/46C01B33/10C01F11/22C01F7/74
CPCC01B21/46C01B33/103C01F11/22C01F7/74
Inventor 刘秋月陈琪郎超
Owner 盛隆资源再生(无锡)有限公司