Method for removing SiO2 and P in fluorine-containing sludge

Abstract

The invention belongs to the technical field of solid waste treatment, and particularly relates to a method for removing SiO2 and P in fluorine-containing sludge. The method comprises the following treatment steps: (1) primarily crushing the fluorine-containing sludge, and screening to remove large-particle impurities, so as to obtain a uniformly refined sludge raw material; and (2) uniformly mixing the sludge raw material obtained in the step (1) with an alkaline regulating agent solution, adding the mixture into a hydrothermal reaction kettle, sealing, carrying out hydrothermal reaction under the conditions of the temperature of 80-200 DEG C and the pressure of 0.5-2 MPa, cooling a reaction product to room temperature after the reaction is finished, and carrying out solid-liquid separation to obtain a solid phase which is the fluorine-containing sludge without SiO2 and P. According to the method disclosed by the invention, the cheap alkaline reagent is used as a regulating agent of the fluorine-containing sludge, so that the dissolution reaction of SiO2 and phosphate can be effectively promoted, strong acid is avoided, the generation of corrosive waste liquid is reduced, and meanwhile, the influence on fluorine-containing components (such as CaF2) is minimum. The method has the advantages of high efficiency, low cost and environmental protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste treatment, and particularly relates to a method for removing SiO 2 and P from fluorine-containing sludge. Background Art

[0002] Fluorine-containing sludge is a common waste in industries such as metallurgy and chemical engineering. The content of silicon dioxide (SiO 2 ) is relatively high, which seriously affects the purification and industrial application of valuable resources such as calcium fluoride (CaF 2 ) in the sludge. In the prior art, the removal efficiency of SiO 2 in fluorine-containing sludge is low, resulting in unqualified purity of the final product or increased processing costs. In addition, the presence of phosphorus element (mainly in the form of phosphate) in fluorine-containing sludge will also affect its subsequent treatment and the purification of valuable resources such as calcium fluoride. Especially in metallurgical and chemical applications, there are strict restrictions on the phosphorus content. At present, the effective removal of phosphorus has become a key problem in the industrial treatment of fluorine-containing sludge.

[0003] The existing main methods for removing SiO 2 from fluorine-containing sludge include acid dissolution method: adding strong acid to dissolve SiO 2 , so as to achieve separation. The disadvantages are large acid consumption, strong corrosiveness, and serious impact on equipment and the environment. Flotation method: using flotation reagents to separate from SiO 2 . The disadvantages are high reagent cost and easy residue, which affect the purity of subsequent products. Physical separation method: using physical methods such as screening and sedimentation to separate SiO 2 . The disadvantage is that the removal efficiency of fine particle SiO 2 is low.

[0004] The existing main methods for removing P from fluorine-containing sludge include acid dissolution method: adding strong acid (such as HCl or H 2 SO 4 ) to dissolve phosphate. The disadvantages are large acid consumption, strong corrosiveness, unsafe operation, and complex waste liquid treatment, increasing environmental risks. Precipitation method: adding calcium salt (such as CaCl 2 ) to form phosphate precipitation. The disadvantages are incomplete phosphate precipitation, strict requirements for operating conditions during the precipitation process, and possible competition with the CaF 2 product, reducing the extraction efficiency of calcium fluoride. Adsorption method: using adsorption materials (such as activated carbon or polymer) to adsorb phosphorus. The disadvantages are limited adsorption capacity, high material cost, and not suitable for large-scale applications.

[0005] The above methods generally have problems of low efficiency, high cost, or environmental unfriendliness, and still cannot meet the requirements of industrial scale applications. Therefore, it is necessary to develop a novel, efficient, economical and environmentally friendly method for removing SiO from fluorine-containing sludge2 and the method of P to meet the requirements of industrial treatment. Summary of the Invention

[0006] Aiming at the disadvantages and deficiencies of the above prior art, the purpose of the present invention is to provide a method for removing SiO in fluorine-containing sludge 2 and P. The method of the present invention is based on a hydrothermal reaction regulated by an alkaline solution, so that SiO 2 and phosphate are converted into soluble compounds and separated from the solid phase. This method combines appropriate additives and optimized hydrothermal conditions to efficiently remove SiO 2 and P elemental components without damaging the CaF in the fluorine-containing sludge 2 component.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A method for removing SiO in fluorine-containing sludge 2 and P, including the following treatment steps:

[0009] (1) Preliminary crushing of the fluorine-containing sludge, screening to remove large particle impurities, and obtaining a uniformly refined sludge raw material;

[0010] (2) Mix the sludge raw material obtained in step (1) evenly with the alkaline regulator solution, add it to a hydrothermal reaction kettle, seal it, and carry out a hydrothermal reaction at a temperature of 80-200 °C and a pressure of 0.5-2 MPa. After the reaction ends, cool the reaction product to room temperature, separate the solid and liquid, and the obtained solid phase is fluorine-containing sludge from which SiO 2 and P are removed.

[0011] Further, the water content of the fluorine-containing sludge in step (1) is 5-10%.

[0012] Further, the solid phase components of the fluorine-containing sludge in step (1) include calcium fluoride (CaF 2 ), silicon dioxide (SiO 2 ) and phosphate (such as Ca 3 (PO 4 ) 2 ).

[0013] More preferably, the mass percentage content of calcium fluoride in the fluorine-containing sludge is 50-70%, the mass percentage content of silicon dioxide is 10-20%, and the mass percentage content of phosphate is 5-15%.

[0014] Further, the screening in step (1) is carried out using a 80-120 mesh sieve.

[0015] Further, the basic regulator solution in step (2) is a sodium hydroxide (NaOH) solution, sodium carbonate (Na 2 CO 3 ) solution or potassium hydroxide (KOH) solution with a concentration of 10-30 wt.%.

[0016] More preferably, the dosage of the basic regulator solution is 10-30% of the mass of the sludge raw material.

[0017] Further, the hydrothermal reaction time in step (2) is 8-72 h.

[0018] Further, in step (2), solid-liquid separation is carried out using a centrifuge, plate and frame filter press or vacuum filter.

[0019] More preferably, when using a centrifuge for solid-liquid separation, the rotation speed is 3000-5000 rpm and the time is 10-30 min; when using a plate and frame filter press for solid-liquid separation, the pressure is 0.1-0.5 MPa and the time is 10-30 min; when using a vacuum filter for solid-liquid separation, the vacuum degree is 0.01-0.1 MPa and the time is 10-30 min.

[0020] The principle of the present invention is as follows: Through the reaction of the fluorine-containing sludge raw material with the basic regulator solution under hydrothermal conditions, under high temperature and high pressure conditions, the basic regulator will react with silicon dioxide and phosphate (such as Ca 3 (PO 4 ) 2 ) in the fluorine-containing sludge to generate soluble silicate (Na 2 SiO 3 ) or phosphate (such as Na 3 PO 4 ) and transfer them to the liquid phase, while not affecting the CaF 2 component in the solid phase, so as to achieve the removal of SiO 2 and P impurities in the fluorine-containing sludge and the enrichment of CaF 2 . The specific reaction formulas are as follows:

[0021] SiO 2 (s)+2NaOH(aq)=Na 2 SiO 3 (aq)+H 2 O(aq);

[0022] SiO 2 (s)+2KOH(aq)=K 2 SiO 3 (aq)+H 2 O(aq);

[0023] SiO 2 (s) + Na 2 CO 3 (aq) = Na 2 SiO 3 (aq) + CO 2 (g);

[0024] Ca 3 (PO 4 ) 2 (s) + 6NaOH(aq) = 2Na 3 PO 4 (aq) + 3Ca(OH) 2 (aq);

[0025] Ca 3 (PO 4 ) 2 (s) + 6KOH(aq) = 2K 3 PO 4 (aq) + 3Ca(OH) 2 (aq).

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) The method of the present invention uses inexpensive alkaline reagents as regulators for fluorine-containing sludge, which can effectively promote the dissolution reaction of SiO 2 and phosphate, avoid the use of strong acids, reduce the generation of corrosive waste liquid, and at the same time have the least impact on fluorine-containing components (such as CaF 2 ). It has the advantages of high efficiency, low cost and environmental protection.

[0028] (2) The method of the present invention can be seamlessly integrated with the existing fluorine-containing sludge treatment process, is suitable for industrial application, and has the advantage of good industrial compatibility. Specific Embodiments

[0029] The present invention will be further described in detail below in conjunction with embodiments, but the embodiments of the present invention are not limited thereto.

[0030] Example 1

[0031] A method for removing SiO 2 and P from fluorine-containing sludge, comprising the following treatment steps:

[0032] (1) The fluorine-containing sludge (calcium fluoride (CaF 2 ) 63.15%, silicon dioxide (SiO 2 ) 14.72% and phosphate (Ca 3 (PO 4 ) 2) 13.13%, moisture content 9%) for preliminary crushing, screening through 100 mesh, removing large particle impurities, to obtain a uniformly refined sludge raw material.

[0033] (2) Mix the sludge raw material obtained in step (1) evenly with a 10 wt% NaOH solution, then add it to a hydrothermal reactor. The dosage of the NaOH solution is 20% of the mass of the sludge raw material. After sealing, carry out a hydrothermal reaction at 100 °C and 1 MPa for 48 h. After the reaction ends, cool the reaction product to room temperature, and use a plate and frame filter press for solid-liquid separation. The pressure for solid-liquid separation is 0.2 MPa and the time is 20 min. The solid phase is the fluorine-containing sludge with SiO 2 and P removed.

[0034] After measurement, the composition of the fluorine-containing sludge after treatment in this example is shown in Table 1 (the content of SiO 2 is determined according to GB / T 5195.8-2006 "Determination of Silicon Dioxide Content in Fluorite"; the phosphorus content is determined according to GB / T 5195.6-2017 "Determination of Phosphorus Content in Fluorite - Spectrophotometry"); the loss rate of calcium fluoride is 6% (the content of CaF 2 is determined according to GB / T 5195.1-2017 "Determination of Calcium Fluoride Content in Fluorite - EDTA Titration Method and Distillation - Potentiometric Titration Method", and the loss rate of calcium fluoride is calculated by comparing the calcium fluoride content before and after treatment).

[0035] Table 1

[0036] Composition <![CDATA[CaF 2 > <![CDATA[SiO 2 > <![CDATA[Ca 3 (PO 4 ) 2 > Fluoride-containing sludge (wt.%) 63.15％ 14.72％ 13.13％ Treated product (wt.%) 93.27％ 3.68％ 1.70％

[0037] From the above results, it can be seen that the method of the present invention can effectively remove SiO 2 and P impurities in the fluorine-containing sludge and enrich CaF 2 , and the loss rate of calcium fluoride is relatively low.

[0038] Example 2

[0039] A method for removing SiO 2 and P from fluorine-containing sludge, comprising the following treatment steps:

[0040] (1) Carry out preliminary crushing and screening of the fluorine-containing sludge through 100 mesh to remove large particle impurities, to obtain a uniformly refined sludge raw material.

[0041] (2) Mix the sludge raw material obtained in step (1) evenly with a NaOH solution with a concentration of 15 wt% and then add it to a hydrothermal reactor. The dosage of the NaOH solution is 20% of the mass of the sludge raw material. After sealing, carry out a hydrothermal reaction at a temperature of 100 °C and a pressure of 1 MPa for 48 h. After the reaction is completed, cool the reaction product to room temperature, and use a plate and frame filter press for solid-liquid separation. The pressure for solid-liquid separation is 0.2 MPa and the time is 20 min. The solid phase is the fluorine-containing sludge after removing SiO 2 and P.

[0042] After measurement, the composition of the fluorine-containing sludge treated in this example is shown in Table 2, and the loss rate of calcium fluoride is 6%.

[0043] Table 2

[0044] Composition <![CDATA[CaF 2 > <![CDATA[SiO 2 > <![CDATA[Ca 3 (PO 4 ) 2 > Fluoride-containing sludge (wt.%) 63.15％ 14.72％ 13.13％ Treated product (wt.%) 95.71％ 2.21％ 0.92％

[0045] It can be seen from the above results that the method of the present invention can effectively remove SiO 2 and P impurities in the fluorine-containing sludge and enrich CaF 2 , and the loss rate of calcium fluoride is relatively low.

[0046] Example 3

[0047] A method for removing SiO 2 and P from fluorine-containing sludge, comprising the following treatment steps:

[0048] (1) Preliminarily crush the fluorine-containing sludge, sieve it through 100 meshes, and remove large particle impurities to obtain a uniformly refined sludge raw material.

[0049] (2) Mix the sludge raw material obtained in step (1) evenly with a NaOH solution with a concentration of 20 wt% and then add it to a hydrothermal reactor. The dosage of the NaOH solution is 20% of the mass of the sludge raw material. After sealing, carry out a hydrothermal reaction at a temperature of 100 °C and a pressure of 1 MPa for 48 h. After the reaction is completed, cool the reaction product to room temperature, and use a plate and frame filter press for solid-liquid separation. The pressure for solid-liquid separation is 0.2 MPa and the time is 20 min. The solid phase is the fluorine-containing sludge after removing SiO 2 and P.

[0050] After measurement, the composition of the fluorine-containing sludge treated in this example is shown in Table 3, and the loss rate of calcium fluoride is 5%.

[0051] Table 3

[0052] Composition <![CDATA[CaF 2 > <![CDATA[SiO 2 > <![CDATA[Ca 3 (PO 4 ) 2 > Fluoride-containing sludge (wt.%) 63.15％ 14.72％ 13.13％ Treated product (wt.%) 96.33％ 1.47％ 0.66％

[0053] It can be seen from the above results that the method of the present invention can effectively remove SiO 2 and P impurities in the fluorine-containing sludge and enrich CaF2 Enrichment with a relatively low loss rate of calcium fluoride.

[0054] Example 4

[0055] A method for removing SiO 2 and P from fluorine-containing sludge, comprising the following treatment steps:

[0056] (1) The fluorine-containing sludge is preliminarily crushed and screened through 100 meshes to remove large particle impurities, obtaining a uniformly refined sludge raw material.

[0057] (2) The sludge raw material obtained in step (1) is mixed evenly with a 25 wt% NaOH solution and then added to a hydrothermal reaction kettle. The dosage of the NaOH solution is 20% of the mass of the sludge raw material. After sealing, a hydrothermal reaction is carried out at a temperature of 100 °C and a pressure of 1 MPa for 48 h. After the reaction ends, the reaction product is cooled to room temperature, and solid-liquid separation is carried out using a plate-and-frame filter press. The pressure for solid-liquid separation is 0.2 MPa and the time is 20 min. The solid phase is the fluorine-containing sludge with SiO 2 and P removed.

[0058] After measurement, the composition of the fluorine-containing sludge after treatment in this example is shown in Table 4, and the loss rate of calcium fluoride is 7%.

[0059] Table 4

[0060] Composition <![CDATA[CaF 2 > <![CDATA[SiO 2 > <![CDATA[Ca 3 (PO 4 ) 2 > Fluoride-containing sludge (wt.%) 63.15％ 14.72％ 13.13％ Treated product (wt.%) 97.63％ 0.74％ 0.39％

[0061] From the above results, it can be seen that the method of the present invention can effectively achieve the removal of SiO 2 and P impurities in the fluorine-containing sludge and the enrichment of CaF 2 with a relatively low loss rate of calcium fluoride.

[0062] Example 5

[0063] A method for removing SiO 2 and P from fluorine-containing sludge, comprising the following treatment steps:

[0064] (1) The fluorine-containing sludge is preliminarily crushed and screened through 100 meshes to remove large particle impurities, obtaining a uniformly refined sludge raw material.

[0065] (2) The sludge raw material obtained in step (1) is mixed evenly with a 20 wt% NaOH solution and then added to a hydrothermal reaction kettle. The dosage of the NaOH solution is 20% of the mass of the sludge raw material. After sealing, a hydrothermal reaction is carried out at a temperature of 120 °C and a pressure of 1.2 MPa for 48 h. After the reaction ends, the reaction product is cooled to room temperature, and solid-liquid separation is carried out using a plate-and-frame filter press. The pressure for solid-liquid separation is 0.2 MPa and the time is 20 min. The solid phase is the fluorine-containing sludge with SiO 2and fluorine-containing sludge of P.

[0066] After measurement, the component composition of the fluorine-containing sludge after treatment in this example is shown in Table 5, and the loss rate of calcium fluoride is 8%.

[0067] Table 5

[0068] Composition <![CDATA[CaF 2 > <![CDATA[SiO 2 > <![CDATA[Ca 3 (PO 4 ) 2 > Fluoride-containing sludge (wt.%) 63.15％ 14.72％ 13.13％ Treated product (wt.%) 97.88％ 0.44％ 0.26％

[0069] It can be seen from the above results that the method of the present invention can effectively remove SiO 2 and P impurities in the fluorine-containing sludge and enrich CaF 2 , and the loss rate of calcium fluoride is relatively low.

[0070] Example 6

[0071] A method for removing SiO 2 and P from fluorine-containing sludge, comprising the following treatment steps:

[0072] (1) Preliminarily crush and screen the fluorine-containing sludge through 100 meshes to remove large particle impurities, and obtain a uniformly refined sludge raw material.

[0073] (2) Mix the sludge raw material obtained in step (1) evenly with a 20 wt% NaOH solution, add it to a hydrothermal reaction kettle, the dosage of the NaOH solution is 20% of the mass of the sludge raw material, seal it and carry out a hydrothermal reaction at a temperature of 100 °C and a pressure of 1 MPa for 36 h. After the reaction is completed, cool the reaction product to room temperature, and carry out solid-liquid separation using a plate and frame filter press. The pressure of the solid-liquid separation is 0.2 MPa and the time is 20 min. The solid phase is the fluorine-containing sludge from which SiO 2 and P are removed.

[0074] After measurement, the component composition of the fluorine-containing sludge after treatment in this example is shown in Table 6, and the loss rate of calcium fluoride is 5%.

[0075] Table 6

[0076] Composition <![CDATA[CaF 2 > <![CDATA[SiO 2 > <![CDATA[Ca 3 (PO 4 ) 2 > Fluoride-containing sludge (wt.%) 63.15％ 14.72％ 13.13％ Treated product (wt.%) 95.11％ 1.77％ 1.44％

[0077] It can be seen from the above results that the method of the present invention can effectively remove SiO 2 and P impurities in the fluorine-containing sludge and enrich CaF 2 , and the loss rate of calcium fluoride is relatively low.

[0078] Example 7

[0079] A method for removing SiO 2 and P from fluorine-containing sludge, comprising the following treatment steps:

[0080] (1) The fluorine-containing sludge is preliminarily crushed and screened through 100 meshes to remove large particle impurities, obtaining a uniformly refined sludge raw material.

[0081] (2) The sludge raw material obtained in step (1) is mixed evenly with a 20 wt% NaOH solution and then added into a hydrothermal reactor. The dosage of the NaOH solution is 20% of the mass of the sludge raw material. After sealing, a hydrothermal reaction is carried out at a temperature of 100 °C and a pressure of 1 MPa for 72 h. After the reaction ends, the reaction product is cooled to room temperature, and solid-liquid separation is carried out using a plate-and-frame filter press. The pressure for solid-liquid separation is 0.2 MPa and the time is 20 min. The solid phase is the fluorine-containing sludge with SiO 2 and P removed.

[0082] After determination, the component composition of the fluorine-containing sludge after treatment in this example is shown in Table 7, and the loss rate of calcium fluoride is 6%.

[0083] Table 7

[0084] Composition <![CDATA[CaF 2 > <![CDATA[SiO 2 > <![CDATA[Ca 3 (PO 4 ) 2 > Fluoride-containing sludge (wt.%) 63.15％ 14.72％ 13.13％ Treated product (wt.%) 97.62％ 0.59％ 0.26％

[0085] From the above results, it can be seen that the method of the present invention can effectively remove SiO 2 and P impurities in the fluorine-containing sludge and enrich CaF 2 , and the loss rate of calcium fluoride is relatively low.

[0086] Example 8

[0087] A method for removing SiO 2 and P from fluorine-containing sludge, comprising the following treatment steps:

[0088] (1) The fluorine-containing sludge is preliminarily crushed and screened through 80 meshes to remove large particle impurities, obtaining a uniformly refined sludge raw material.

[0089] (2) The sludge raw material obtained in step (1) is mixed evenly with a 20 wt% NaOH solution and then added into a hydrothermal reactor. The dosage of the NaOH solution is 10% of the mass of the sludge raw material. After sealing, a hydrothermal reaction is carried out at a temperature of 160 °C and a pressure of 1.5 MPa for 12 h. After the reaction ends, the reaction product is cooled to room temperature, and solid-liquid separation is carried out using a centrifuge. The rotation speed for solid-liquid separation is 4000 rpm and the time is 30 min. The solid phase is the fluorine-containing sludge with SiO 2 and P removed.

[0090] After determination, the component composition of the fluorine-containing sludge after treatment in this example is shown in Table 8, and the loss rate of calcium fluoride is 8%.

[0091] Table 8

[0092] Composition <![CDATA[CaF 2 > <![CDATA[SiO 2 > <![CDATA[Ca 3 (PO 4 ) 2 <!-- 5 -->]]> Fluoride-containing sludge (wt.%) 63.15％ 14.72％ 13.13％ Treated product (wt.%) 96.87％ 1.47％ 1.05％

[0093] As can be seen from the above results, the method of the present invention can effectively remove SiO 2 and P impurities in the fluorine-containing sludge and enrich CaF 2 , and the loss rate of calcium fluoride is relatively low.

[0094] Example 9

[0095] A method for removing SiO 2 and P from fluorine-containing sludge, comprising the following treatment steps:

[0096] (1) The fluorine-containing sludge is preliminarily crushed and screened through 120 meshes to remove large-particle impurities, and a uniformly refined sludge raw material is obtained.

[0097] (2) The sludge raw material obtained in step (1) is mixed evenly with a NaOH solution with a concentration of 20 wt%, and the amount of the NaOH solution is 30% of the mass of the sludge raw material. Then it is added to a hydrothermal reaction kettle, sealed, and subjected to a hydrothermal reaction at a temperature of 120 °C and a pressure of 1.2 MPa for 15 h. After the reaction, the reaction product is cooled to room temperature, and solid-liquid separation is carried out using a vacuum filter. The vacuum degree of the solid-liquid separation is 0.1 MPa and the time is 10 min. The solid phase is the fluorine-containing sludge from which SiO 2 and P have been removed.

[0098] After measurement, the composition of the fluorine-containing sludge after treatment in this example is shown in Table 9, and the loss rate of calcium fluoride is 7%.

[0099] Table 9

[0100] Composition <![CDATA[CaF 2 > <![CDATA[SiO 2 > <![CDATA[Ca 3 (PO 4 ) 2 > Fluoride-containing sludge (wt.%) 63.15％ 14.72％ 13.13％ Treated product (wt.%) 96.19％ 1.18％ 1.05％

[0101] As can be seen from the above results, the method of the present invention can effectively remove SiO 2 and P impurities in the fluorine-containing sludge and enrich CaF 2 , and the loss rate of calcium fluoride is relatively low.

[0102] Example 10

[0103] A method for removing SiO 2 and P from fluorine-containing sludge, comprising the following treatment steps:

[0104] (1) The fluorine-containing sludge is preliminarily crushed and screened through 100 meshes to remove large-particle impurities, and a uniformly refined sludge raw material is obtained.

[0105] (2) Mix the sludge raw material obtained in step (1) evenly with a KOH solution having a concentration of 20 wt% and add it to a hydrothermal reactor. The dosage of the KOH solution is 20% of the mass of the sludge raw material. After sealing, carry out a hydrothermal reaction at a temperature of 150 °C and a pressure of 1.5 MPa for 10 h. After the reaction is completed, cool the reaction product to room temperature, and perform solid-liquid separation using a plate-and-frame filter press. The pressure for solid-liquid separation is 0.2 MPa and the time is 20 min. The solid phase is the fluorine-containing sludge with SiO 2 and P removed.

[0106] It is measured that the composition of the fluorine-containing sludge after treatment in this example is shown in Table 10, and the loss rate of calcium fluoride is 6%.

[0107] Table 10

[0108] Composition <![CDATA[CaF 2 > <![CDATA[SiO 2 > <![CDATA[Ca 3 (PO 4 ) 2 > Fluoride-containing sludge (wt.%) 63.15％ 14.72％ 13.13％ Treated product (wt.%) 96.72％ 1.03％ 1.05％

[0109] It can be seen from the above results that the method of the present invention can effectively remove SiO 2 and P impurities in the fluorine-containing sludge and enrich CaF 2 , and the loss rate of calcium fluoride is relatively low.

[0110] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for removing SiO2 and P from fluorine-containing sludge, characterized in that: The processing steps include: (1) Preliminary crushing of fluorine-containing sludge, screening to remove large particle impurities, and obtaining uniformly refined sludge raw materials; (2) The sludge raw material obtained in step (1) is mixed evenly with the alkaline regulating agent solution and then added into a hydrothermal reactor. After sealing, the hydrothermal reaction is carried out at a temperature of 80 to 200° C. and a pressure of 0.5 to 2 MPa. After the reaction is completed, the reaction product is cooled to room temperature and the solid-liquid separation is performed. The solid phase obtained is the fluorine-containing sludge from which SiO2 and P are removed.

2. The method for removing SiO2 and P from fluorine-containing sludge according to claim 1, characterized in that: The water content of the fluorine-containing sludge in step (1) is 5-10%.

3. The method for removing SiO2 and P from fluorine-containing sludge according to claim 1, characterized in that: The solid phase components of the fluoride-containing sludge in step (1) include calcium fluoride, silicon dioxide and phosphate.

4. The method for removing SiO2 and P from fluorine-containing sludge according to claim 3, characterized in that: The mass percentage of calcium fluoride in the fluorine-containing sludge is 50-70%, the mass percentage of silicon dioxide is 10-20%, and the mass percentage of phosphate is 5-15%.

5. The method for removing SiO2 and P from fluorine-containing sludge according to claim 1, characterized in that: The screening in step (1) is performed using a sieve with a mesh size of 80 to 120.

6. The method for removing SiO2 and P from fluorine-containing sludge according to claim 1, characterized in that: The alkaline regulating agent solution in step (2) is a sodium hydroxide solution, a sodium carbonate solution or a potassium hydroxide solution with a concentration of 10 to 30 wt.%.

7. A method for removing SiO2 and P from fluorine-containing sludge according to claim 6, characterized in that: The dosage of the alkaline regulator solution is 10-30% of the mass of the sludge raw material.

8. The method for removing SiO2 and P from fluorine-containing sludge according to claim 1, characterized in that: The time of the hydrothermal reaction in step (2) is 8 to 72 hours.

9. The method for removing SiO2 and P from fluorine-containing sludge according to claim 1, characterized in that: The solid-liquid separation in step (2) is carried out by using a centrifuge, a plate and frame filter press or a vacuum filter.

10. The method for removing SiO2 and P from fluorine-containing sludge according to claim 9, characterized in that: The rotation speed of the centrifuge for solid-liquid separation is 3000-5000rpm, and the time is 10-30min; the pressure of the plate and frame filter press for solid-liquid separation is 0.1-0.5MPa, and the time is 10-30min; the vacuum degree of the vacuum filter for solid-liquid separation is 0.01-0.1MPa, and the time is 10-30min.