Process for producing hydrofluoric acid by synthesizing artificial fluorite from fluorine-containing industrial wastewater

Abstract

According to the process for producing hydrofluoric acid by synthesizing artificial fluorite from fluorine-containing industrial wastewater provided by the invention, the artificial fluorite obtained by treating the fluorine-containing industrial wastewater reacts with sulfuric acid to generate hydrogen fluoride, and the hydrogen fluoride is directly condensed and rectified to obtain anhydrous hydrogen fluoride and form a byproduct fluosilicic acid. The method is simple in process, fluorine-containing industrial wastewater can be directly used for producing hydrofluoric acid, formation of new solid waste is avoided, cyclic utilization of resources is achieved, the requirement for natural fluorite is reduced, the production cost of hydrofluoric acid is reduced, the method has high market competitiveness, the fluorine-containing industrial wastewater is recycled, circular economy is formed, and the method conforms to the environment-friendly concept and is worthy of popularization and application. The popularization is worthy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrofluoric acid production, and particularly relates to a process for producing hydrofluoric acid by using artificial fluorite synthesized from fluorine-containing industrial wastewater. BACKGROUND

[0002] Hydrofluoric acid is a chemical product with wide application, and can be divided into anhydrous hydrofluoric acid and aqueous acid. The anhydrous hydrofluoric acid can form the aqueous acid when dissolved in water, and is mainly used for preparing fluorine salt, fluorohalogenated hydrocarbon, fluorine refrigerant, etching glass, impregnating wood, and electrolyzing elemental fluorine. When the fluorine-containing industrial wastewater is treated, the fluorine in the wastewater is converted into calcium fluoride crystal nucleus by the method of chemical induced crystallization, and is separated from the liquid phase. The precipitate is named artificial fluorite. Natural fluorite, also known as fluorite, is mainly composed of calcium fluoride. Fluorite is a strategic material controlled by the state, and the reserves in nature are becoming less and less. The existing production process of hydrofluoric acid needs to consume a large amount of natural fluorite, which causes the price of raw materials to rise sharply, and makes the production of hydrofluoric acid have no profit, thereby restricting the long-term development of the fluorine chemical industry. SUMMARY

[0003] The present application provides a process for producing hydrofluoric acid by using artificial fluorite synthesized from fluorine-containing industrial wastewater, which reduces the demand for natural fluorite, reduces the production cost of hydrofluoric acid, and recycles the fluorine-containing industrial wastewater.

[0004] To solve the above technical problems, the present application provides a process for producing hydrofluoric acid by using artificial fluorite synthesized from fluorine-containing industrial wastewater, which comprises the following steps:

[0005] a. The fluorine-containing industrial wastewater is reacted with calcium source and inducer to generate calcium fluoride crystals, and then the calcium fluoride crystals are dried to obtain fluorite powder, and the fluorite powder is stored in a fluorite storage bin;

[0006] b. A certain amount of fluorite powder prepared in step a is sent to a rotary reaction furnace;

[0007] c. The fuming sulfuric acid and the sulfuric acid in which hydrogen fluoride in tail gas is absorbed in an acid absorption tower are sent to a mixed acid tank, and mixed with dilute acid from a washing tower to obtain mixed acid;

[0008] d. The mixed acid prepared in step c is sent into the rotary reaction furnace;

[0009] e. The rotary reaction furnace is heated to provide the heat required for the reaction of the substances in the rotary reaction furnace;

[0010] f. The slag discharged from the tail of the rotary reaction furnace is neutralized with slaked lime to neutralize excess acid, and then is sent to a slag storage hopper;

[0011] g. The gas generated in step e is sent to a scrubbing tower for dust removal and cooling. The small amount of water in the gas in the scrubbing tower is mixed with the hydrogen fluoride gas in the form of water vapor;

[0012] h. The gas in the scrubbing tower is sent through a primary cooler, a first hydrogen fluoride condenser, and a second hydrogen fluoride condenser in sequence.

[0013] i. The condensate obtained by condensing the gas in the primary cooler is returned to the scrubbing tower. The condensate obtained by condensing the gas in the first hydrogen fluoride condenser is sent to a rectification tower to remove heavy components. The H2SO4 and H2O at the bottom of the rectification tower are returned to the scrubbing tower. The gas at the top of the rectification tower is sent to a degassing tower to remove light components. The SO2 and SiF4 gas at the top of the degassing tower is the product. The anhydrous hydrogen fluoride at the bottom of the degassing tower is the product.

[0014] j. The uncondensed gas from the second hydrogen fluoride condenser and the uncondensed gas discharged from the top of the degassing tower are sent to a sulfuric acid absorption tower to absorb the hydrogen fluoride in the gas using sulfuric acid. The gas that is not absorbed in the sulfuric acid absorption tower is sent to a tail gas tower to remove acidic gas and then discharged into the air.

[0015] k. The scrubbing liquid in the tail gas tower is sent to a waste liquid treatment device. The treated qualified wastewater is discharged into the drainage system.

[0016] Preferably, the rotary reaction furnace comprises a jacket. The mixed acid in step d is sent to the jacket. The jacket is heated to 450°C using flue gas in step e.

[0017] Preferably, the scrubbing liquid in the scrubbing tower is sulfuric acid. The temperature of the gas after being scrubbed in the scrubbing tower in step g is 150°C.

[0018] Preferably, the temperature at the bottom of the rectification tower is 30°C. The temperature at the top of the rectification tower is 19.5°C.

[0019] Preferably, the temperature at the top of the degassing tower is below 10°C. The temperature at the bottom of the degassing tower is 19°C.

[0020] Preferably, the calcium source in step a is lime milk or calcium chloride.

[0021] The application has the advantages that the application provides a process for producing hydrofluoric acid by using fluorine-containing industrial wastewater to synthesize artificial fluorite, wherein the artificial fluorite obtained by treating the fluorine-containing industrial wastewater is reacted with sulfuric acid to generate hydrogen fluoride, which is directly condensed, and then distilled to obtain anhydrous hydrogen fluoride, and the hydrogen fluoride is reacted with SiF4 to generate fluosilicic acid for storage, and the fluosilicic acid is used to generate hydrofluoric acid when the hydrofluoric acid is needed, so that the process is simple, the fluorine-containing industrial wastewater can be directly used to produce hydrofluoric acid, the demand for natural fluorite is reduced, the production cost of the hydrofluoric acid is reduced, and the process has strong market competitiveness, the fluorine-containing industrial wastewater is recycled, a circular economy is formed, the process is in line with the environmental protection concept, and is worth promoting. DETAILED DESCRIPTION

[0022] In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments.

[0023] Based on the described embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present disclosure.

[0024] The utility model provides a kind of process for producing hydrofluoric acid by using fluorine-containing industrial wastewater to synthesize artificial fluorite, comprising the following steps:

[0025] a, fluorine-containing industrial wastewater is reacted with fluoride ions in wastewater by adding calcium source and inducer to generate calcium fluoride crystals, then the calcium fluoride crystals are dried to obtain fluorite powder, and the fluorite powder is stored in fluorite storage bin;

[0026] b, a certain amount of fluorite powder prepared by step a is sent to a rotary reaction furnace by a screw conveyor;

[0027] c, fuming sulfuric acid and sulfuric acid absorbing hydrogen fluoride in tail gas in acid absorption tower are sent to mixed acid tank, and mixed with dilute acid from washing tower to obtain mixed acid;

[0028] d, the mixed acid prepared in step c is sent into the rotary reaction furnace, and the heating of the rotary reaction furnace uses coal gas producer;

[0029] e, the rotary reaction furnace is heated to provide the required heat for the reaction in the rotary reaction furnace;

[0030] f, the slag discharged from the rotary reaction furnace is neutralized with slaked lime to neutralize excess acid, and then sent to slag hopper, and the gaseous product of the reaction is mainly hydrogen fluoride;

[0031] g. The gas generated in step e is sent to a scrubbing tower for dust removal and cooling. The small amount of water in the gas entering the scrubbing tower is mixed with the hydrogen fluoride gas in the form of water vapor;

[0032] h. The gas in the scrubbing tower is sequentially passed through a primary cooler, a hydrogen fluoride primary condenser, and a hydrogen fluoride secondary condenser.

[0033] i. The condensate obtained by condensing the gas in the primary cooler is returned to the scrubbing tower. The temperature of the gas after being condensed in the primary cooler is 60°C. The condensate obtained by condensing the gas in the hydrogen fluoride primary condenser is sent to a rectification tower to remove heavy components such as H2SO4. The H2SO4 and H2O at the bottom of the rectification tower are returned to the scrubbing tower. The gas at the top of the rectification tower is sent to a degassing tower to remove light components such as SO2 and SiF4. The gas at the top of the degassing tower is SO2 and SiF4 gas. The substance at the bottom of the degassing tower is anhydrous hydrogen fluoride.

[0034] j. The uncondensed gas passing through the hydrogen fluoride secondary condenser and the uncondensed gas discharged from the top of the degassing tower are sent to a sulfuric acid absorption tower to absorb the hydrogen fluoride in the gas using sulfuric acid in the tower. The gas not absorbed in the sulfuric acid absorption tower is sent to a tail gas tower to wash off the acidic gas and then discharged into the air.

[0035] k. The scrubbing liquid in the tail gas tower is sent to a waste liquid treatment device. The treated qualified wastewater is discharged into the drainage system.

[0036] Based on the above embodiment, the rotary reaction furnace comprises a jacket. In step d, the mixed acid is sent into the jacket. In step e, the jacket is heated to 450°C using flue gas.

[0037] Based on the above embodiment, the scrubbing liquid in the scrubbing tower is sulfuric acid. In step g, the temperature of the gas before entering the scrubbing tower is about 350°C. The temperature of the gas after being scrubbed in the scrubbing tower is 150°C.

[0038] Based on the above embodiment, the temperature at the bottom of the rectification tower is 30°C. The temperature at the top of the rectification tower is 19.5°C.

[0039] Based on the above embodiment, the temperature at the top of the degassing tower is below 10°C. The temperature at the bottom of the degassing tower is 19°C. Since the boiling point of SiF4 is -86°C and the boiling point of SO2 is -86°C, and the boiling point of hydrogen fluoride is 19.5°C, the gas at the top of the degassing tower is SO2 and SiF4 gas. The substance at the bottom of the degassing tower is anhydrous hydrogen fluoride. The tail gas of the degassing tower is SO2 and SiF4.

[0040] Based on the above embodiment, the calcium source in step a is lime milk or calcium chloride.

[0041] The synthetic fluorite obtained by treating fluorine-containing industrial wastewater is reacted with sulfuric acid, and the reaction equation is: CaF2+H2SO4=CaSO4+2HF, the generated hydrogen fluoride is directly condensed, then distilled to obtain anhydrous hydrogen fluoride, and the hydrogen fluoride is reacted with SiF4 to generate fluosilicic acid for convenient storage, and when hydrogen fluoride acid is needed, the fluosilicic acid is reacted to generate hydrogen fluoride acid. The process is simple, the hydrogen fluoride acid can be directly produced by using the fluorine-containing industrial wastewater, the demand for natural fluorite is reduced, the production cost of hydrogen fluoride acid is reduced, and the process has strong market competitiveness. The fluorine-containing industrial wastewater is recycled, a circular economy is formed, the process meets the environmental protection concept, and is worth promoting.

[0042] The above embodiments only describe the preferred embodiments of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by ordinary engineering technicians in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A process for the production of hydrofluoric acid from synthetic fluorite produced from fluorine-containing industrial waste water, characterized in that, The method comprises the following steps: a. reacting fluorine ions in the fluorine-containing industrial wastewater with a calcium source and an inducing agent to form calcium fluoride crystals, drying the calcium fluoride crystals to obtain fluorite powder, and storing the fluorite powder in a fluorite storage bin; b. sending a certain amount of fluorite powder obtained in step a to a rotary reaction furnace; c. sending fuming sulfuric acid and sulfuric acid that has absorbed hydrogen fluoride in tail gas in an acid absorption tower to a mixed acid tank, and mixing the mixed acid with dilute acid from a washing tower to obtain mixed acid; d. sending the mixed acid obtained in step c to the rotary reaction furnace; e. heating the rotary reaction furnace to provide heat required for reaction of substances in the rotary reaction furnace; f. sending slag discharged from the rotary reaction furnace to a slag storage hopper after neutralizing excess acid with slaked lime; g. sending the gas generated in step e to a washing tower for dust removal and cooling, and mixing a small amount of water in the gas with hydrogen fluoride gas in the form of water vapor; h. sequentially passing the gas in the washing tower through a primary cooler, a hydrogen fluoride primary condenser, and a hydrogen fluoride secondary condenser; i. returning the condensate obtained by condensing the gas in the primary cooler to the washing tower, returning the condensate obtained by condensing the gas in the hydrogen fluoride primary condenser to a rectifying tower to remove heavy components, returning H2SO4 and H2O at the bottom of the rectifying tower to the washing tower, passing the gas at the top of the rectifying tower to a degassing tower to remove light components, and obtaining SO2 and SiF4 gas at the top of the degassing tower, and obtaining anhydrous hydrogen fluoride at the bottom of the degassing tower; j. passing the uncondensed gas through the hydrogen fluoride secondary condenser and the uncondensed gas discharged from the top of the degassing tower to a sulfuric acid absorption tower, absorbing hydrogen fluoride in the gas with sulfuric acid in the sulfuric acid absorption tower, and then sequentially passing the gas to a first water washing tower and a second water washing tower to generate fluorosilicic acid, and passing the gas not absorbed in the sulfuric acid absorption tower to a tail gas tower to wash away acidic gas and then discharging the gas to the air; k. sending the washing liquid in the tail gas tower to a waste liquid treatment device, and discharging qualified wastewater treated to a drainage system.

2. A process for the preparation of a process for the production of hydrofluoric acid from artificial fluorite synthesized from fluoro-industrial waste water as claimed in claim 1, wherein, The rotary reaction furnace comprises a jacket, the mixed acid in step d is sent to the jacket, and the jacket is heated to 450°C with flue gas in step e.

3. A process for the preparation of a process for the production of hydrofluoric acid from artificial fluorite synthesized from fluoro-industrial waste water as claimed in claim 2, wherein, The washing liquid in the washing tower is sulfuric acid, and the temperature of the gas after being washed by the washing tower is 150°C in step g.

4. A process for the preparation of a process for the production of hydrofluoric acid from artificial fluorite synthesized using fluoro-industrial wastewater according to claim 3, characterized by, The temperature at the bottom of the rectifying tower is 30°C, and the temperature at the top of the rectifying tower is 19.5°C.

5. A process for the preparation of a process for the production of hydrofluoric acid from artificial fluorite synthesized using fluoro-industrial wastewater according to claim 4, characterized by, The temperature at the top of the degassing tower is below 10°C, and the temperature at the bottom of the degassing tower is 19°C.

6. A process for the preparation of a process for the production of hydrofluoric acid from artificial fluorite synthesized using fluoro-industrial wastewater as claimed in claim 1, wherein, The calcium source in step a is lime milk or calcium chloride.