CN-116835533-B - Method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts

CN116835533BCN 116835533 BCN116835533 BCN 116835533BCN-116835533-B

Abstract

The invention relates to a method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts, which adopts fluosilicic acid solution with the concentration of 12-18% of byproducts in the wet phosphoric acid production process to react with unqualified products in the Mannheim potassium sulfate production process, and then carries out vacuum filtration and separation to obtain a potassium fluosilicate filter cake and dilute sulfuric acid solution containing KCl, K 2 SO 4 and other salt substances. Adding the potassium fluosilicate filter cake into concentrated sulfuric acid with the concentration of more than 95% of heat for thermal decomposition reaction, carrying out vacuum distillation and stirring in the reaction process to obtain a solution containing SiF 4 , HF gas and potassium sulfate, and cooling the solution containing potassium sulfate and returning the solution containing potassium sulfate to the first step for recycling. The raw materials used in the whole process are byproducts, and the cost is low. The used mannham potassium sulfate byproduct not only can improve the fluorine yield of the process system, but also can relieve the condition that silicon dioxide is converted into silica gel to block the process system. All substances, waste water, waste gas and waste residues in the process are recycled, and the whole process is safe and energy-saving.

Inventors

WEI TIANRONG
ZHANG WENCHAO

Assignees

湖北三宁化工股份有限公司

Dates

Publication Date: 20260508
Application Date: 20230710

Claims (8)

1. A method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts, which is characterized by comprising the following steps: 1) Adding unqualified products in the production process of the mannham potassium sulfate into fluosilicic acid solution with the concentration of 12-18% which is a byproduct in the production process of wet phosphoric acid to obtain reaction slurry; 2) Vacuum filtering and separating the reaction slurry obtained in the step 1) to obtain a potassium fluosilicate filter cake and a dilute sulfuric acid solution; 3) Carrying out vacuum concentration on the dilute sulfuric acid solution obtained in the step 2) to obtain concentrated sulfuric acid with the concentration of more than 95% of heat, using the concentrated sulfuric acid for subsequent thermal decomposition reaction and washing gas containing SiF 4 and HF, naturally cooling the crystal containing potassium sulfate salt obtained by vacuum concentration, returning to the step 1) for reaction, and discharging acid water generated by vacuum concentration into a wet-process phosphoric acid production system; 4) Adding the potassium fluosilicate filter cake obtained in the step 2) into hot concentrated sulfuric acid with the concentration of more than 95% to carry out thermal decomposition reaction, carrying out reduced pressure distillation and stirring in the reaction process, obtaining a solution containing SiF 4 , HF gas and potassium sulfate through the thermal decomposition reaction, cooling the solution containing potassium sulfate, and returning the solution containing potassium sulfate to the step 1) to carry out the reaction; 5) Washing and dehydrating the SiF 4 and HF-containing gas obtained in the step 4) by using more than 95% concentrated sulfuric acid cooled in the step 3), and returning the obtained washing liquid to the step 4) for thermal decomposition reaction; 6) Condensing the SiF 4 and the HF gas after washing in the step 5) to obtain liquid-phase HF and SiF 4 gas; 7) Purifying and rectifying the liquid phase HF obtained in the step 6) to obtain an anhydrous hydrogen fluoride finished product with the concentration of more than 99.8%, and returning the residual liquid obtained by rectification to the step 4) for reaction; 8) Introducing SiF 4 gas obtained in the step 6) into the dilute sulfuric acid solution obtained in the step 2) to hydrolyze, so as to obtain hydrolyzed slurry and HF-based gas, discharging the HF-based gas into the step 5) through a vacuum pump to wash and dehydrate to recover HF, filtering and separating the hydrolyzed slurry to obtain an acidic solution containing KF, K 2 SO 4 and KCl and silicon dioxide, returning the acidic solution containing KF, K 2 SO 4 and KCl to the step 1), and continuously reacting to improve the yield of fluorine, and recycling the silicon dioxide to prepare white carbon black; And (3) completing the preparation of anhydrous hydrogen fluoride by comprehensively utilizing byproducts.
2. The method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts according to claim 1, wherein the ratio of the amount of potassium oxide in the mannheim potassium sulfate reject to the amount of fluorosilicic acid in the fluorosilicic acid solution with the concentration of 12% -18% in the step 1) is (1-2): 1, the reaction temperature is controlled to be 10-40 ℃, and the reaction time is controlled to be 10-60 min.
3. The method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts according to claim 1, wherein the main components of the mannheim potassium sulfate reject in the step 1) are water-soluble K 2 O：45%-50%,Cl - ≤2%,H 2 O less than or equal to 1.5%, free acid less than or equal to 1.5% and pH3-5, and the reject can provide H 2 SO 4 for a process system and improve the yield of fluorine.
4. The method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts according to claim 1, which is characterized in that the vacuum filtration in the step 2) is carried out, and the vacuum degree is controlled at-20 kPa to-80 kPa.
5. The method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts according to claim 1, which is characterized in that the vacuum concentration temperature of the dilute sulfuric acid solution in the step 3) is controlled to be 100-180 ℃, the vacuum degree is controlled to be minus 20kPa to minus 80kPa, the concentration of the obtained hot concentrated sulfuric acid is controlled to be more than 95%, and the temperature of the hot concentrated sulfuric acid is controlled to be 100-180 ℃.
6. The method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts according to claim 1, wherein the reduced pressure distillation temperature in the thermal decomposition reaction process in the step 4) is controlled to be 100-180 ℃, the vacuum degree is controlled to be-20 kPa to-80 kPa, the stirring speed is controlled to be 200-400r/min, the ratio of the amount of potassium fluosilicate substances in a potassium fluosilicate filter cake added in the thermal decomposition reaction to the amount of substances of sulfuric acid in the total concentrated sulfuric acid added in the reaction is controlled to be 1:1, the reaction time is controlled to be 10-300min, and concentrated sulfuric acid is added first in the thermal decomposition reaction and then the potassium fluosilicate filter cake is added.
7. The method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts according to claim 1, wherein the concentrated sulfuric acid washing temperature in the step 5) is controlled to be 10-45 ℃.
8. The method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts according to claim 1, wherein the condensation temperature in the step 6) is controlled to be-5-10 ℃.

Description

Method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts Technical Field The invention relates to the technical field of hydrogen fluoride production, in particular to a method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts. Background The anhydrous hydrogen fluoride is used as a basic raw material of a fluoride industry chain, the market demand is increased increasingly, the price is raised gradually, and a plurality of domestic enterprises see the considerable profits of the anhydrous hydrogen fluoride product and put into the research and development of the production process. In summary, the production route of anhydrous hydrogen fluoride mainly comprises two methods, namely a traditional fluorite method and a method for decomposing fluosilicic acid which is a byproduct in the process of producing wet-process phosphoric acid by utilizing phosphate ore. The second method for producing anhydrous hydrogen fluoride becomes the first choice for domestic enterprises and is also the key step for widening the industrial chain for wet-process phosphoric acid production enterprises. At present, the method for producing anhydrous hydrogen fluoride by fluosilicic acid by domestic wet phosphoric acid enterprises is layered endlessly, but the process technology is basically the same as or different from each other, and has advantages and disadvantages, and the actual process capable of realizing industrial production is less. The process for producing anhydrous hydrogen fluoride by fluosilicic acid can be divided into the following ways, namely, the way of decomposing fluosilicic acid by sulfuric acid, the way of converting fluosilicic acid into related salts and then decomposing by sulfuric acid, the way of directly decomposing by fluosilicic acid, and the way of converting fluosilicic acid into related salts and then directly decomposing by sulfuric acid. For example, patent publication No. CN101948114A discloses a method for preparing silicon tetrafluoride and anhydrous hydrogen fluoride by acidifying sodium fluosilicate with sulfuric acid, but the technological process is too simple, and the actual production is difficult. As another example, patent publication No. CN102275877a discloses a method for producing anhydrous hydrogen fluoride and silicon tetrafluoride by using fluosilicic acid, but a rotary kiln in fluorite production is used in the process, which has large energy consumption and difficult operation. As another example, the patent with publication No. CN108439340a discloses a method for preparing anhydrous hydrogen fluoride, which does not describe the process flow, and is difficult to realize, and dilute sulfuric acid generated in the process is not effectively utilized, but phosphogypsum without added value is produced, which wastes resources. For another example, the patent publication CN112897466a discloses a method for producing anhydrous hydrogen fluoride by using fluosilicic acid in phosphoric acid, which describes the process flow, but the whole process is not optimized, partial materials are not fully utilized, the yield of the anhydrous hydrogen fluoride cannot reach the highest, and the raw material is fluorine-containing phosphoric acid, and the high content of the impurities is unfavorable for the whole process. The processes have various disadvantages such as high production cost, high energy consumption, difficult operation, no effective utilization of byproducts in the production process, difficult industrial implementation, and the like. Disclosure of Invention In view of the defects of the prior art, the invention combines the characteristics of wet phosphoric acid production and Mannheim potassium sulfate production processes, provides a method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts, and can reduce the production cost, comprehensively utilize byproduct resources, realize safety, high efficiency, economy, environmental protection, simple operation, and product purity of more than 99.8 by using byproducts fluosilicic acid and unqualified products in the Mannheim potassium sulfate production process in the wet phosphoric acid production process, and realize industrial production. In order to achieve the purpose of the invention, the technical scheme of the invention is as follows: a method for preparing anhydrous hydrogen fluoride by comprehensively utilizing byproducts, which comprises the following steps: 1) Adding unqualified products in the production process of the mannham potassium sulfate into fluosilicic acid solution with the concentration of 12-18% which is a byproduct in the production process of wet phosphoric acid to obtain reaction slurry; 2) Vacuum filtering and separating the reaction slurry obtained in the step 1) to obtain a potassium fluosilicate filter cake and a dilute sulfuric acid solution; 3) Carrying out vacuum concentration on the dilute sulfuric acid