Seed crystal for recovering silicon ions in wastewater, preparation method and nucleation granulation process

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a seed crystal for recycling silicon ions in wastewater, a preparation method and a nucleation granulation process, the preparation method is simple, convenient and low in cost, used raw materials are pure, no other pollutants are brought in, and industrial production is facilitated; the seed crystal prepared by the invention can reinforce silicon ion recovery in practical application, so that silicon ions in water body are crystallized and grown on the seed crystal, the utilization rate of the seed crystal is improved, the removal rate of the silicon ions is improved, the purposes of reducing cost and improving efficiency of a silicon-containing wastewater treatment process are achieved, and industrial production and application are facilitated.

Description

Technical Field

[0001] The present disclosure relates to the technical field of wastewater treatment, and in particular to a seed crystal, a preparation method and a core crystal granulation process for recovering silicon ions in wastewater. Background Art

[0002] Silicon-containing wastewater refers to wastewater containing a high concentration of silicon ions, which is usually generated during the production process of semiconductors, solar cells, electronic components, glass and other industries. This wastewater has the following hazards: 1) Pollution to the environment: Direct discharge of silicon-containing wastewater into rivers, lakes and other water bodies will cause the water to become opaque and turbid, and in severe cases will damage the water ecological environment; 2) Threat to human health: Silicon is a harmful substance, and long-term exposure to silicon-containing wastewater may affect the functions of the human nervous system, liver, kidneys and other organs.

[0003] At present, the main treatment methods for this type of wastewater are: (1) chemical treatment method, which mainly uses chemical reactions to convert silicon substances in silicon-containing wastewater into substances such as silicates or silica gel that are easy to precipitate, filter and remove; (2) biological treatment method, which mainly uses the action of biological active agents to convert silicon substances in wastewater into substances such as ammonia nitrogen and nitrate nitrogen, and uses microbial treatment to remove pollutants such as organic matter; (3) membrane separation method, which mainly uses reverse osmosis membranes, ultrafiltration membranes, etc. to intercept silicon substances in wastewater on the membrane, so that the wastewater has no or low silicon content after treatment; (4) electrochemical treatment method, which mainly uses electrochemical reactions to convert silicon substances in silicon-containing wastewater into substances that are easy to precipitate or remove, and can also remove other pollutants at the same time.

[0004] However, the above wastewater treatment methods all have the problem of high cost, and the solid matter produced after treatment is generally difficult to recycle, resulting in a waste of resources. Some methods may also produce secondary pollution during wastewater treatment.

[0005] In summary, how to provide a treatment method with low cost, good silicon removal effect and the ability to recycle the solid matter produced after treatment has become a problem that needs to be solved urgently. Summary of the invention

[0006] In order to solve the above technical problems, the present disclosure provides a seed crystal, a preparation method and a nuclear crystal granulation process for recovering silicon ions in wastewater. The seed crystal prepared by the present disclosure is used in the nuclear crystal granulation process, which can efficiently remove silicon in the wastewater and improve the reuse rate of the wastewater. At the same time, the obtained granulation body is dense, avoiding the generation of a large amount of hazardous waste sludge, and effectively reducing the treatment cost.

[0007] In a first aspect, the present disclosure provides a method for preparing seed crystals for recovering silicon ions in wastewater, the preparation method comprising the following steps:

[0008] The silicon source, the base and the solvent are mixed and reacted to form a precipitate;

[0009] The obtained precipitate is subjected to aging treatment, solid-liquid separation and drying in sequence to obtain seed crystals for recovering silicon ions in wastewater;

[0010] The molar ratio of the silicon source to the base is (1-2):(1-2).

[0011] The molar ratio of the silicon source to the base may be 1:1, 1.5:2, 1.2:1, 2:1.5, 2:1, etc., but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0012] The appropriate addition ratio of silicon source to alkali helps to improve the quality and capacity of seed crystals. If too little silicon source is added, there will be too few silicon ion sites on the surface of the generated seed crystals, reducing the crystallization rate; if too little alkali is added, it will lead to failure to generate a sufficient number of seed crystals, resulting in a waste of reagents.

[0013] The following are preferred technical solutions of the present disclosure, but are not intended to be limitations of the technical solutions provided by the present disclosure. Through the following technical solutions, the technical objectives and beneficial effects of the present disclosure can be better achieved and realized.

[0014] As a preferred technical solution of the present disclosure, the silicon source includes sodium silicate and / or ethyl orthosilicate.

[0015] Preferably, the base comprises aqueous ammonia and / or sodium hydroxide.

[0016] Preferably, the solvent comprises water.

[0017] As a preferred technical solution of the present disclosure, the mixing operation includes: mixing the silicon source and the alkali with the solvent respectively to obtain a silicon source solution and a first alkali solution respectively; and then adding the silicon source solution to the first alkali solution.

[0018] Preferably, the addition rate of the silicon source solution to the first alkaline solution is 1-3 mL / s, for example 1 mL / s, 1.5 mL / s, 12 mL / s, 2.5 mL / s or 3 mL / s, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0019] Preferably, the concentration of the silicon source solution is 1-5 mol / L, such as 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0020] Preferably, the concentration of the first alkaline solution is 2-10 mol / L, such as 2 mol / L, 4 mol / L, 6 mol / L, 8 mol / L or 10 mol / L, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0021] Preferably, stirring is performed during the mixing process.

[0022] Preferably, the stirring speed is 200-500 r / min, such as 200 r / min, 300 r / min, 400 r / min or 500 r / min, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0023] As a preferred technical solution of the present disclosure, the reaction temperature is 30-80°C, for example 30°C, 40°C, 50°C, 60°C, 70°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0024] Preferably, the reaction time is 1-5 h, such as 1 h, 2 h, 3 h, 4 h or 5 h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0025] Preferably, the aging treatment comprises: allowing the obtained precipitate to stand in the reaction system for 1-24 hours, for example, 1 hour, 2 hours, 5 hours, 9 hours, 12 hours, 15 hours, 18 hours, 21 hours or 24 hours, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0026] Preferably, the temperature of the aging treatment is 0-20°C higher than the temperature of the reaction, such as 0°C, 5°C, 10°C, 15°C or 20°C, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0027] As a preferred technical solution of the present disclosure, the drying temperature is 80-120°C, such as 80°C, 90°C, 100°C, 110°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0028] Preferably, the drying time is 1-2 h, such as 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h or 2 h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0029] In a second aspect, the present disclosure provides a seed crystal for recovering silicon ions in wastewater, wherein the seed crystal is prepared by the preparation method described in the first aspect.

[0030] In a third aspect, the present disclosure provides a nuclear crystal granulation process for recovering silicon ions from wastewater, using the seed crystals prepared by the preparation method described in the first aspect or the seed crystals described in the second aspect;

[0031] The core crystal granulation process comprises:

[0032] Mixing the seed crystals, silicon-containing wastewater and a precipitant;

[0033] The silicon-containing wastewater reacts with the precipitant to generate silicon-containing precipitates which crystallize in an orderly manner on the surface of the seed crystals to form granules.

[0034] As a preferred technical solution of the present disclosure, the core crystal granulation process is carried out in a core crystal granulation reactor, and the core crystal granulation reactor includes an outer cylinder and an inner cylinder;

[0035] The inner cylinder is suspended in the outer cylinder and penetrates vertically;

[0036] The lower end of the side wall of the outer cylinder is independently provided with a wastewater inlet pipe and a precipitant feed pipe, and the setting height is lower than the bottom end of the inner cylinder; the top of the outer cylinder is provided with a toothed overflow weir and a water outlet pipe; the bottom of the outer cylinder is provided with a granulation body discharge pipe.

[0037] As a preferred technical solution of the present disclosure, the core crystal granulation process comprises the following steps:

[0038] (1) filling the seed crystal into the inner cylinder of the nuclear crystal granulation reactor;

[0039] (2) silicon-containing wastewater and a precipitant are introduced into the nuclear crystal granulation reactor to make the seed crystals fluidized, silicon ions in the silicon-containing wastewater react with the precipitant to generate silicon-containing precipitates which are crystallized in an orderly manner on the surface of the seed crystals to form granules, the obtained granules are discharged from the bottom of the nuclear crystal granulation reactor, and the regenerated water obtained after the nuclear crystal granulation treatment is discharged from the upper part of the nuclear crystal granulation reactor.

[0040] Preferably, the filling height of the seeds in the nuclear crystal granulation reactor in step (1) is 5-50% of the height of the inner tube, for example 5%, 10%, 20%, 30%, 40% or 50%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0041] As a preferred technical solution of the present invention, the pH of the silicon-containing wastewater in step (2) is adjusted to 8.5-10.5, such as 8.5, 9, 9.5, 10 or 10.5, etc. before entering the nuclear crystal granulation reactor, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0042] Preferably, the pH of the silicon-containing wastewater is adjusted using an acid solution or a second alkaline solution.

[0043] Preferably, the acid solution comprises hydrochloric acid and / or sulfuric acid.

[0044] Preferably, the second alkaline solution comprises sodium hydroxide solution and / or potassium hydroxide solution.

[0045] Preferably, the concentrations of the acid solution and the second alkaline solution are independently 1-3 mol / L, such as 1 mol / L, 2 mol / L or 3 mol / L, but are not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0046] Preferably, the precipitant in step (2) is introduced in the form of a solution, and the precipitant includes one or more of sodium chlorate, sodium aluminate, calcium chloride, magnesium chloride or magnesium sulfate, such as a combination of sodium chlorate and sodium aluminate, a combination of magnesium chloride and magnesium sulfate, etc.

[0047] As a preferred technical solution of the present invention, in the nuclear crystal granulation process, the number of the nuclear crystal granulation reactors is not less than 2, and multiple nuclear crystal granulation reactors are arranged in series, and the regenerated water discharged from the upper-stage nuclear crystal granulation reactor is used as feed wastewater for the next-stage nuclear crystal granulation reactor.

[0048] Compared with the prior art, the technical solution provided by the embodiments of the present disclosure has the following advantages:

[0049] (1) The method for preparing seed crystals for recovering silicon ions in wastewater provided by the present disclosure is simple, convenient, low-cost, uses pure raw materials without other pollutants, and is conducive to industrial production.

[0050] (2) The crystal seeds prepared in the present disclosure can enhance silicon ion recovery in practical applications, causing silicon ions in the water to adhere to the crystal seeds and grow, thereby improving the utilization rate of the crystal seeds and increasing the removal rate of silicon ions, which is beneficial to industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0053] Figure 1This is a SEM image of the granules obtained in the core crystal granulation process described in Example 1 of the present disclosure. DETAILED DESCRIPTION

[0054] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0055] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0056] The core crystal granulation reactor used in the following embodiments and comparative examples of the present disclosure includes an outer cylinder and an inner cylinder;

[0057] The inner cylinder is suspended in the outer cylinder and penetrates vertically;

[0058] The lower end of the side wall of the outer cylinder is independently provided with a wastewater inlet pipe and a precipitant feed pipe, and the setting height is lower than the bottom end of the inner cylinder; the top of the outer cylinder is provided with a toothed overflow weir and a water outlet pipe; the bottom of the outer cylinder is provided with a granulation body discharge pipe.

[0059] Example 1

[0060] This embodiment provides a method for preparing seed crystals and a core crystal granulation process for recovering silicon ions in wastewater, the preparation method comprising the following steps:

[0061] Prepare 1 mol / L sodium silicate solution and 2 mol / L sodium hydroxide solution;

[0062] At 30°C, the sodium silicate solution was added to the sodium hydroxide solution at a dropping speed of 1 mL / s, and stirred at a speed of 200 r / min to react for 3 hours. The final molar ratio of sodium silicate to sodium hydroxide was controlled to be 1:1.2, and a precipitate was generated after the reaction;

[0063] The obtained precipitate was aged at 30° C. for 12 h, then washed with deionized water, and dried at 100° C. for 1 h to obtain seed crystals for recovering silicon ions in wastewater.

[0064] The seed crystals prepared in this embodiment are used to carry out a nucleation granulation process, including:

[0065] (1) filling the seed crystals for recovering silicon ions from wastewater into the inner cylinder of the nuclear crystal granulation reactor, the filling height being 5% of the height of the inner cylinder;

[0066] (2) introducing wastewater with a silicon ion concentration of 100 mg / L and a pH of 9 from the lower part of the nuclear crystal granulation reactor at a flow rate of 2000 L / h, and at the same time, introducing a sodium aluminate solution with a concentration of 600 mg / L from the lower part of the nuclear crystal granulation reactor at a flow rate of 60 L / h, so that the seed crystals are in a fluidized state;

[0067] Silicon ions in the silicon-containing wastewater react with sodium aluminate to generate silicon-containing precipitates and crystallize in an orderly manner on the surface of the seed crystals to form granules. The obtained granules are discharged from the bottom of the nuclear crystal granulation reactor, and the regenerated water obtained after the nuclear crystal granulation treatment is discharged from the upper part of the nuclear crystal granulation reactor.

[0068] Among them, the SEM image of the obtained granules is as follows Figure 1 shown.

[0069] Example 2

[0070] This embodiment provides a method for preparing seed crystals and a core crystal granulation process for recovering silicon ions in wastewater, the preparation method comprising the following steps:

[0071] Prepare 5 mol / L sodium silicate solution and 10 mol / L sodium hydroxide solution;

[0072] At 50° C., the sodium silicate solution was added to the sodium hydroxide solution at a dropping speed of 2 mL / s, and stirred at a speed of 500 r / min to react for 1 h. The final molar ratio of sodium silicate to sodium hydroxide was controlled to be 1.5:2, and a precipitate was generated after the reaction;

[0073] The obtained precipitate was aged at 52° C. for 24 h, then washed with deionized water, and dried at 80° C. for 2 h to obtain seed crystals for recovering silicon ions in wastewater.

[0074] The seed crystals prepared in this embodiment are used to carry out a nucleation granulation process, including:

[0075] (1) filling the seed crystals for recovering silicon ions in wastewater into the inner cylinder of the nuclear crystal granulation reactor, the filling height being 30% of the height of the inner cylinder;

[0076] (2) introducing wastewater with a silicon ion concentration of 150 mg / L and a pH of 9.1 from the lower part of the nuclear crystal granulation reactor at a flow rate of 2000 L / h, and at the same time, introducing a magnesium sulfate solution with a concentration of 600 mg / L from the lower part of the nuclear crystal granulation reactor at a flow rate of 60 L / h, so that the seed crystals are in a fluidized state;

[0077] Silicon ions in the silicon-containing wastewater react with magnesium sulfate to generate silicon-containing precipitates and crystallize in an orderly manner on the surface of the seed crystals to form granules. The obtained granules are discharged from the bottom of the nuclear crystal granulation reactor, and the regenerated water obtained after the nuclear crystal granulation treatment is discharged from the upper part of the nuclear crystal granulation reactor.

[0078] Example 3

[0079] This embodiment provides a method for preparing seed crystals and a core crystal granulation process for recovering silicon ions in wastewater, the preparation method comprising the following steps:

[0080] Prepare 3 mol / L sodium silicate solution and 7 mol / L sodium hydroxide solution;

[0081] At 80° C., the sodium silicate solution was added to the sodium hydroxide solution at a dropping speed of 2.5 mL / s, and stirred at a speed of 300 r / min to react for 5 hours. The final molar ratio of sodium silicate to sodium hydroxide was controlled to be 1.8:2, and a precipitate was generated after the reaction;

[0082] The obtained precipitate was aged at 80° C. for 16 h, then washed with deionized water, and dried at 120° C. for 1.5 h to obtain seed crystals for recovering silicon ions in wastewater.

[0083] The seed crystals prepared in this embodiment are used to carry out a nuclear crystal granulation process, wherein the nuclear crystal granulation device comprises a primary nuclear crystal granulation reactor and a secondary nuclear crystal granulation reactor arranged in series;

[0084] The core crystal granulation process comprises:

[0085] (1) filling the seed crystals for recovering silicon ions from wastewater into the inner cylinders of the primary nucleus crystal granulation reactor and the secondary nucleus crystal granulation reactor respectively, with the filling height being 50% of the height of the inner cylinder;

[0086] (2) introducing wastewater with a silicon ion concentration of 300 mg / L and a pH of 9.1 from the lower part of the primary nuclear crystal granulation reactor at a flow rate of 3000 L / h, and at the same time, introducing a magnesium sulfate solution with a concentration of 600 mg / L from the lower part of the nuclear crystal granulation reactor at a flow rate of 60 L / h, so that the seed crystals are in a fluidized state;

[0087] Silicon ions in silicon-containing wastewater react with magnesium sulfate to generate silicon-containing precipitates and crystallize in an orderly manner on the surface of the seed crystals to form a primary granulation body, which is discharged from the bottom of the primary nuclear crystal granulation reactor, and the primary regenerated water obtained after the nuclear crystal granulation treatment flows out from the upper part of the primary nuclear crystal granulation reactor and enters the secondary nuclear crystal granulation reactor;

[0088] (3) When the primary regenerated water enters the secondary nuclear crystal granulation reactor, a magnesium chloride solution with a concentration of 500 mg / L is introduced from the lower part of the secondary nuclear crystal granulation reactor at a flow rate of 60 L / h to fluidize the seed crystals. The silicon ions in the primary regenerated water react with the magnesium chloride to generate silicon-containing precipitates which crystallize in an orderly manner on the surface of the seed crystals to form a secondary granulation body. The obtained secondary granulation body is discharged from the bottom of the secondary nuclear crystal granulation reactor. The secondary regenerated water obtained after the nuclear crystal granulation treatment flows out from the upper part of the secondary nuclear crystal granulation reactor.

[0089] Comparative Example 1

[0090] This comparative example provides a method for preparing seed crystals and a nuclear crystal granulation process for recovering silicon ions in wastewater. The preparation method refers to the preparation method in Example 1, with the only difference being that the final molar ratio of sodium silicate to sodium hydroxide is controlled to be 1:3.

[0091] The core crystal granulation process refers to the core crystal granulation process in Example 1, with the only difference being that the seed crystals prepared in Example 1 are replaced by the seed crystals of this comparative example.

[0092] Comparative Example 2

[0093] This comparative example provides a method for preparing seed crystals and a nuclear crystal granulation process for recovering silicon ions in wastewater. The preparation method refers to the preparation method in Example 1, with the only difference being that the final molar ratio of sodium silicate to sodium hydroxide is controlled to be 3:1.

[0094] The core crystal granulation process refers to the core crystal granulation process in Example 1, with the only difference being that the seed crystals prepared in Example 1 are replaced by the seed crystals of this comparative example.

[0095] Comparative Example 3

[0096] This comparative example provides a seed crystal for recovering silicon ions in wastewater, wherein the seed crystal is quartz sand.

[0097] The core crystal granulation process refers to the core crystal granulation process in Example 1, with the only difference being that the seed crystals prepared in Example 1 are replaced by the seed crystals of this comparative example.

[0098] After running for 120 hours, the pH of the regenerated water, the concentration of silicon ions in the regenerated water and the turbidity after the nuclear crystal granulation process in the above Examples 1-3 and Comparative Examples 1-3 were measured, and the removal rate of silicon ions was calculated. The results are shown in Table 1.

[0099] Table 1

[0100]

[0101] It can be seen from Table 1 that, compared with existing commercial seed crystals, the seed crystals prepared by the preparation method disclosed in the present invention have a silicon ion removal rate of more than 90% in actual applications, and the turbidity is below 8.9 NTU, which effectively improves the recovery rate of silicon ions and achieves the purpose of reducing costs and increasing efficiency in the silicon-containing wastewater treatment process.

[0102] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0103] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing seed crystals for recovering silicon ions from wastewater, characterized in that: The preparation method comprises the following steps: The silicon source, the base and the solvent are mixed and reacted to form a precipitate; The obtained precipitate is subjected to aging treatment, solid-liquid separation and drying in sequence to obtain seed crystals for recovering silicon ions in wastewater; The molar ratio of the silicon source to the base is (1-2):(1-2).

2. The preparation method according to claim 1, characterized in that: The silicon source includes sodium silicate and / or tetraethyl orthosilicate; Preferably, the base comprises aqueous ammonia and / or sodium hydroxide; Preferably, the solvent comprises water.

3. The preparation method according to claim 1 or 2, characterized in that: The mixing operation includes: mixing the silicon source and the alkali with the solvent respectively to obtain a silicon source solution and a first alkali solution respectively; and then adding the silicon source solution to the first alkali solution; Preferably, the silicon source solution is added to the first alkaline solution at a rate of 1-3 mL / s; Preferably, the concentration of the silicon source solution is 1-5 mol / L; Preferably, the concentration of the first alkaline solution is 2-10 mol / L; Preferably, stirring is performed during the mixing process; Preferably, the stirring speed is 200-500r / min.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The reaction temperature is 30-80°C; Preferably, the reaction time is 1-5h; Preferably, the aging treatment comprises: allowing the obtained precipitate to stand in the reaction system for 1-24 hours; Preferably, the temperature of the aging treatment is 0-20°C higher than the temperature of the reaction.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The drying temperature is 80-120°C; Preferably, the drying time is 1-2 hours.

6. A seed crystal for recovering silicon ions from wastewater, characterized in that: The seed crystal is prepared by the preparation method according to any one of claims 1 to 5.

7. A nuclear crystal granulation process for recovering silicon ions from wastewater, characterized in that: Using the seed crystal prepared by the preparation method according to any one of claims 1 to 5 or the seed crystal according to claim 6; The core crystal granulation process comprises: Mixing the seed crystals, silicon-containing wastewater and a precipitant; The silicon-containing wastewater reacts with the precipitant to generate silicon-containing precipitates which crystallize in an orderly manner on the surface of the seed crystals to form granules.

8. The core crystal granulation process according to claim 7, characterized in that: The core crystal granulation process is carried out in a core crystal granulation reactor, and the core crystal granulation reactor comprises an outer cylinder and an inner cylinder; The inner cylinder is suspended in the outer cylinder and penetrates vertically; The lower end of the side wall of the outer cylinder is independently provided with a wastewater inlet pipe and a precipitant feed pipe, and the setting height is lower than the bottom end of the inner cylinder; the top of the outer cylinder is provided with a toothed overflow weir and a water outlet pipe; the bottom of the outer cylinder is provided with a granulation body discharge pipe.

9. The core crystal granulation process according to claim 8, characterized in that: The core crystal granulation process comprises the following steps: (1) filling the seed crystal into the inner cylinder of the nuclear crystal granulation reactor; (2) introducing silicon-containing wastewater and a precipitant into the nuclear crystal granulation reactor to make the seed crystal in a fluidized state, and silicon ions in the silicon-containing wastewater react with the precipitant to generate silicon-containing precipitates which are crystallized in an orderly manner on the surface of the seed crystal to form granules, and the obtained granules are discharged from the bottom of the nuclear crystal granulation reactor, and the regenerated water obtained after the nuclear crystal granulation treatment is discharged from the upper part of the nuclear crystal granulation reactor; Preferably, in step (1), the filling height of the seed crystals in the nuclear crystal granulation reactor is 5-50% of the height of the inner cylinder; Preferably, the pH of the silicon-containing wastewater in step (2) is adjusted to 8.5-10.5 before being introduced into the nucleus crystallization granulation reactor; Preferably, the pH of the silicon-containing wastewater is adjusted using an acid solution or a second alkaline solution; Preferably, the acid solution comprises hydrochloric acid and / or sulfuric acid; Preferably, the second alkaline solution comprises sodium hydroxide solution and / or potassium hydroxide solution; Preferably, the concentrations of the acid solution and the second alkaline solution are independently 1-3 mol / L; Preferably, the precipitant in step (2) is introduced in the form of a solution, and the precipitant includes one or more of sodium chlorate, sodium metaaluminate, calcium chloride, magnesium chloride or magnesium sulfate.

10. The core crystal granulation process according to any one of claims 7 to 9, characterized in that: In the nuclear crystal granulation process, the number of the nuclear crystal granulation reactors is not less than 2, and a plurality of the nuclear crystal granulation reactors are arranged in series, and the regenerated water discharged from the upper-stage nuclear crystal granulation reactor is used as feed wastewater for the lower-stage nuclear crystal granulation reactor.

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