CN113603095A - Defluorination residue recovery process - Google Patents
Defluorination residue recovery process Download PDFInfo
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- CN113603095A CN113603095A CN202111031994.XA CN202111031994A CN113603095A CN 113603095 A CN113603095 A CN 113603095A CN 202111031994 A CN202111031994 A CN 202111031994A CN 113603095 A CN113603095 A CN 113603095A
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- defluorination
- residue
- phosphoric acid
- defluorinated
- recovery process
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/08—Compounds containing halogen
- C01B33/10—Compounds containing silicon, fluorine, and other elements
- C01B33/103—Fluosilicic acid; Salts thereof
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Abstract
The invention discloses a defluorination residue recovery process which is characterized by comprising the following steps: firstly, defluorination residues generated in the production process of feed-grade calcium hydrophosphate are settled through a sedimentation basin, so that the water content is further reduced; filtering the settled defluorinated slag with a plate-and-frame filter press, wherein the filtrate is used for producing feed-grade calcium hydrophosphate, and the filter residue is repulped with water and then conveyed to a phosphoric acid device through a pipeline; thirdly, reacting the repulped defluorination residue with concentrated sulfuric acid and active silicon dioxide in a defluorination residue reaction tank, and directly feeding the reacted slurry into a phosphoric acid reaction tank; fourthly, the unreacted defluorination residue in the phosphoric acid reaction tank continues to react with sulfuric acid, and further fluorine is dissolved into a liquid phase; fifthly, the mixed material after reaction is put into a phosphoric acid filter for solid-liquid separation, the solid phase enters a phosphogypsum slag yard for stockpiling, and the fluorine in the liquid phase is promoted. The invention can realize the recovery of fluorine element in the defluorination residue, and the yield can reach more than 75%.
Description
Technical Field
The invention relates to the technical field of feed-grade calcium hydrophosphate and wet-process phosphoric acid production, in particular to a process for recovering feed-grade calcium hydrophosphate defluorination residues in wet-process phosphoric acid production.
Background
In the production process of feed grade calcium hydrophosphate, the fluorine content in the end product is ensured to meet the requirement. In the front end of the process, lime is needed to carry out defluorination reaction on the low-concentration phosphoric acid solution, the product obtained by the defluorination reaction is mainly calcium fluoride, and in addition, partial calcium oxide and a little calcium hydroxide are remained. At present, most enterprises mix defluorination residues with water for size mixing and then store the defluorination residues and phosphogypsum in a mixing mode, so that on one hand, the waste of fluorine resources is caused, and on the other hand, a certain risk is brought to the stable storage of the phosphogypsum.
The chinese patent No. 201110319555.9 "a method for recovering phosphorus and fluorine from defluorinated slag" provides an effective method for recovering defluorinated slag, but it does not describe how to clearly recover fluorine in the defluorinated slag reaction process, and active silica is not used in the reaction step, and the recovery form of fluorine is different from the present application, and the recovery rate of fluorine resource is relatively low compared with the present application.
Disclosure of Invention
The invention aims to solve the technical scheme that an effective recovery process of defluorination residues in the production process of feed-grade calcium hydrophosphate is provided aiming at the defects of the prior art.
In order to effectively recover defluorination residues in the production process of recovering feed-grade calcium hydrophosphate, the inventor collects and arranges related data through a plurality of experiments. The invention discloses an effective recovery production process of defluorination residue in the production process of feed grade calcium hydrophosphate, which comprises the following steps:
firstly, defluorination residues generated in the production process of feed-grade calcium hydrophosphate are settled through a sedimentation basin, so that the water content is further reduced;
filtering the defluorinated slag with a plate frame, wherein the filtrate is used for producing feed-grade calcium hydrophosphate, and repulping the filter residue with a small amount of water and then conveying the filter residue to a phosphoric acid device through a pipeline;
thirdly, reacting the repulped defluorination residue with concentrated sulfuric acid and active silicon dioxide in a reaction tank, and directly feeding the reacted slurry into a phosphoric acid reaction tank; the specific reaction equation is as follows:
CaF2+H2SO4(Thick)
CaSO4+2HF↑
SiO2 + 4HF → SiF4↑ + 2H2O
3SiF4 + 2H2O → 2H2SiF6 + SiO2
Fourthly, the unreacted defluorination residue in the phosphoric acid reaction tank continues to react with sulfuric acid, and further fluorine is dissolved into a liquid phase;
fifthly, the mixed material after reaction is put into a phosphoric acid filter for solid-liquid separation, the solid phase enters a phosphogypsum slag yard for stockpiling, and the fluorine in the liquid phase is promoted.
In the step 1 of the method, the sedimentation tank is a square sedimentation tank or a conical bottom sedimentation tank; the sedimentation tank is made of carbon steel lining rubber or stainless steel.
In the step 2 of the method, the plate-and-frame filter press is a plate-and-frame filter press used in a common sewage treatment plant; the treatment capacity of the plate-and-frame filter press is 50 m per unit3/h -70m3The filter area of the filter press is 270 m3A table of-300 m3A table.
In the step 3 of the method, the defluorination residue reaction tank is made of stainless steel or carbon steel lined with rubber and then lined with carbon bricks. The reaction condition of the defluorination residue and the sulfuric acid active silica is constant temperature reaction at 80-82 ℃.
In the step 3 of the method, the dosage of the active silicon dioxide is determined according to the mass of the defluorination residue, and the molar ratio of the active silicon dioxide to the defluorination residue and the concentrated sulfuric acid is 1:2: 2.
In the step 4 of the method, the phosphoric acid reaction tank can be a square grid multi-tank or a single-tank multi-stirring paddle tank, and is determined according to the actual conditions of enterprises. The system temperature in the phosphoric acid reaction tank is controlled to be 80-82 ℃; the free sulfur trioxide is controlled between 35 and 40 g/l.
In the 5 th step of the method, the phosphoric acid filter is a tilting pan filter or a turntable filter; the filtration vacuum degree is controlled at 20-45 kPa. The effective filtering area of the tilting pan type filter exceeds 200m3The maximum filtration capacity reaches 600 m3/h。
The invention has the beneficial effects that: the recovery of fluorine element in the defluorination residue can be realized, and the yield can reach more than 75%. The method provided by the invention has the advantages that the fluorine resource is efficiently recovered, the great economic benefit is brought to enterprises, the environmental protection risk of defluorination residue stockpiling is reduced, and the method is suitable for all wet-process phosphoric acid production enterprises.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
Example 1: taking 30g of dried defluorination residue, repulping with 251g of clear water, wherein the defluorination residue has 17.2 percent of fluorine content and 26.55 percent of calcium content, adding 4.54g of active silicon dioxide and 25.24g of 98 percent concentrated sulfuric acid into the repulped defluorination residue, and reacting at 82 ℃; 268.96g of slurry is obtained through reaction, suction filtration is carried out on the slurry to obtain 210.22g of filtrate, the density of the filtrate is 1.086g/l, the fluorine content in the filtrate is 1.93%, the fluorine content in the filter cake is 0.26%, and 78.70% of fluorine in the defluorination residue is transferred to a liquid phase to be recovered through calculation.
Example 2: the process technology adopted by a certain factory to recover fluorine resources in the wet-process phosphoric acid production process has the following specific scheme:
firstly, adopting primary (adding flocculating agent polyacrylamide) to settle defluorination residues; and discharging the bottom-layer high-solid-content material from the bottom, and pumping the material to a plate-and-frame filter press for filter pressing.
② the filter pressing treatment capacity of each plate frame is 50 m3/h -70m3The filter area of the filter press is 270 m3/h -300m3And repulping the plate-frame slag subjected to filter pressing by using clear water.
③ 50 m after repulping defluorination residues3H and 4.43m3Reacting sulfuric acid/h and active silicon dioxide 2.45kg/h at the constant temperature of 82 ℃; the reacted mixture is pumped into a phosphoric acid reaction tank.
Fourthly, the system temperature in the phosphoric acid reaction tank is controlled at 82 ℃ to continue the reaction for 3.5 hours. The slurry after reaction is sent to a phosphoric acid filter by a pump; wherein the free sulfur trioxide is controlled at 35 g/l.
Fifthly, the effective filtering area of the tilting pan type filter exceeds 200m3The maximum filtration capacity reaches 600 m3H, controlling the filtration vacuum degree at 45 kPa; the fluorine content in the filtered filtrate is increased from the original 1.75 percent to 1.85 percent, and the fluorine in the defluorination residues is recovered.
Claims (10)
1. The defluorination residue recovery process is characterized by comprising the following steps:
firstly, defluorination residues generated in the production process of feed-grade calcium hydrophosphate are settled through a sedimentation basin, so that the water content is further reduced;
filtering the settled defluorinated slag with a plate-and-frame filter press, wherein the filtrate is used for producing feed-grade calcium hydrophosphate, and the filter residue is repulped with water and then conveyed to a phosphoric acid device through a pipeline;
thirdly, reacting the repulped defluorination residue with concentrated sulfuric acid and active silicon dioxide in a defluorination residue reaction tank, and directly feeding the reacted slurry into a phosphoric acid reaction tank;
fourthly, the unreacted defluorination residue in the phosphoric acid reaction tank continues to react with sulfuric acid, and further fluorine is dissolved into a liquid phase;
fifthly, the mixed material after reaction is put into a phosphoric acid filter for solid-liquid separation, the solid phase enters a phosphogypsum slag yard for stockpiling, and the fluorine in the liquid phase is promoted.
2. The defluorinated slag recovery process according to claim 1, characterized in that: in the step 1, the sedimentation tank is a square sedimentation tank or a conical bottom sedimentation tank; the sedimentation tank is made of carbon steel lining rubber or stainless steel.
3. The defluorinated slag recovery process according to claim 1, characterized in that: in the step 2, the plate-and-frame filter press is a plate-and-frame filter press used in a common sewage treatment plant; the treatment capacity of the plate-and-frame filter press is 50 m per unit3/h -70m3The filter area of the filter press is 270 m3A table of-300 m3A table.
4. The defluorinated slag recovery process according to claim 1, characterized in that: in the step 3, the defluorination residue reaction tank is made of stainless steel materials or carbon steel lined with rubber and then lined with carbon bricks.
5. The defluorinated slag recovery process according to claim 1, characterized in that: in the step 3, the defluorination residue and the sulfuric acid active silica react under the constant temperature of 80-82 ℃.
6. The defluorinated slag recovery process according to claim 1, characterized in that: in the step 3, the dosage of the active silicon dioxide is determined according to the mass of the defluorination residue, and the molar ratio of the active silicon dioxide to the defluorination residue and the concentrated sulfuric acid is 1:2: 2.
7. The defluorinated slag recovery process according to claim 1, characterized in that: in the 4 th step, the phosphoric acid reaction tank is selected from a square multi-tank or a single-tank multi-stirring paddle tank.
8. The defluorinated slag recovery process according to claim 1, characterized in that: in the 4 step, the temperature of the system in the phosphoric acid reaction tank is controlled to be 80-82 ℃; the free sulfur trioxide is controlled between 35 and 40 g/l.
9. The defluorinated slag recovery process according to claim 1, characterized in that: in the 5 th step, the phosphoric acid filter is a tilting pan filter or a rotary table filter; the filtration vacuum degree is controlled at 20-45 kPa.
10. The defluorinated slag recovery process according to claim 8, characterized in that: the effective filtering area of the tilting pan type filter exceeds 200m3The maximum filtration capacity reaches 600 m3/h。
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114057170A (en) * | 2021-12-20 | 2022-02-18 | 瓮福（集团）有限责任公司 | Method for synthesizing phosphorus pentafluoride and preparing lithium hexafluorophosphate by solid phase method |
| CN114133276A (en) * | 2021-12-23 | 2022-03-04 | 四川省汉源化工总厂 | White fertilizer recycling treatment method |
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- 2021-09-03 CN CN202111031994.XA patent/CN113603095A/en active Pending
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| CN114057170A (en) * | 2021-12-20 | 2022-02-18 | 瓮福（集团）有限责任公司 | Method for synthesizing phosphorus pentafluoride and preparing lithium hexafluorophosphate by solid phase method |
| CN114133276A (en) * | 2021-12-23 | 2022-03-04 | 四川省汉源化工总厂 | White fertilizer recycling treatment method |
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