Method for preparing composite silicon fertilizer from silicon-rich slag

Abstract

The application provides a method for preparing composite silicon fertilizer from silicon-rich residue, which is produced in the production process of phosphogypsum; the silicon-rich residue is first washed with water to remove soluble fluorine; then alkaline components such as carbide slag, calcium hydroxide and calcium oxide are added to fix fluorine; after treatment, the silicon-rich residue is mixed with water glass, polyacrylamide, superabsorbent resin, carboxymethyl starch, sodium carboxymethyl cellulose and other adhesives in a certain proportion, and then granulated to prepare granular composite silicon fertilizer; the effective silicon content in the composite silicon fertilizer is more than 25%, the effective phosphorus content is more than 0.2%, the potassium content is more than 0.3% and the composite silicon fertilizer does not contain soluble fluorine; the method realizes the resource utilization of the silicon-rich residue separated from the phosphogypsum, improves the economy of the overall phosphogypsum purification process and is beneficial to the popularization of the phosphogypsum purification process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wet-process phosphoric acid, and particularly relates to a method for preparing composite silicon fertilizer from silicon-rich residue. BACKGROUND

[0002] Low and medium grade collophanite has high impurity content. In the process of wet-process phosphoric acid, the insoluble silicon, iron, aluminum and other impurities in collophanite are enriched in phosphogypsum, which affects the resource utilization of phosphogypsum. By flotation or source upgrading technology, the quality of phosphogypsum can be improved, and the resource utilization of phosphogypsum can be promoted. However, the silicon-rich residue separated from phosphogypsum contains a small amount of harmful components such as fluorine, calcium, sulfur, phosphorus, iron, aluminum, potassium, sodium and magnesium, and has complex composition and difficult treatment and utilization.

[0003] CN115672568A discloses a method for preparing low-silicon high-grade phosphogypsum by reverse flotation desilication of phosphogypsum waste residue, which comprises the following steps: mixing phosphogypsum waste residue with water to obtain a slurry, then adding a desilication collector for reverse flotation roughing operation to obtain reverse flotation roughing tailings and reverse flotation roughing concentrate; mixing the reverse flotation roughing tailings with the desilication collector for scavenging operation to obtain scavenging concentrate and tailings; returning the scavenging concentrate to the reverse flotation roughing operation; mixing the reverse flotation roughing concentrate with the desilication collector for cleaning operation to obtain cleaning tailings and low-silicon high-grade phosphogypsum concentrate; and returning the cleaning tailings to the reverse flotation roughing operation. The method realizes the separation of gypsum and silicon dioxide by reverse flotation, further improves the quality of phosphogypsum, and provides a new beneficiation method and technical support for the resource utilization of phosphogypsum.

[0004] CN112110470A discloses a method for treating phosphogypsum waste residue, which comprises the following steps: washing, drying and grinding the phosphogypsum waste residue to obtain pretreated phosphogypsum powder; mixing glycerol and anhydrous ethanol, stirring uniformly, then adding dodecyltrimethylammonium bromide, and continuing to stir until the solid is dissolved to obtain solution A; mixing the pretreated phosphogypsum powder and nitric acid solution, stirring, then adding sulfuric acid solution and continuing to stir to obtain solution B, slowly adding solution A to solution B, and treating with intermittent ultrasonic waves to obtain a mixture, which is transferred to a reaction kettle for reaction. After cooling to room temperature, the reaction liquid is filtered, and the obtained solid is dried to obtain nanometer calcium sulfate crystals. The method is simple in operation, and the obtained nanometer calcium sulfate crystals have good stability, a particle size of 30-50nm and good dispersion.

[0005] However, the above method is complex in operation and high in cost for treating phosphogypsum waste residue for reuse.

[0006] Therefore, it is necessary to provide a method for preparing composite silicon fertilizer from phosphogypsum waste residue, so as to realize resource utilization of the silicon-rich residue obtained by separating phosphogypsum, and improve the economy of the overall phosphogypsum purification process. SUMMARY

[0007] To solve the above technical problems, the present application provides a method for preparing composite silicon fertilizer from silicon-rich residue, which is produced in the process of producing phosphogypsum. The method comprises the following steps:

[0008] To achieve the above purpose, the present application adopts the following technical solutions:

[0009] The present application aims to provide a method for preparing composite silicon fertilizer from silicon-rich residue, which comprises the following steps:

[0010] (1) washing the silicon-rich residue with water to remove soluble fluorine; the silicon-rich residue is produced in the process of producing phosphogypsum;

[0011] (2) mixing the silicon-rich residue after water washing with a calcium-based alkaline component to perform fluorine fixation treatment;

[0012] (3) mixing the silicon-rich residue after fluorine fixation treatment with a binder to perform granulation to obtain granular composite silicon fertilizer;

[0013] The effective silicon content in the composite silicon fertilizer is more than 25%, the effective phosphorus content is more than 0.2%, the potassium content is more than 0.3%, and the composite silicon fertilizer does not contain soluble fluorine.

[0014] The method for preparing composite silicon fertilizer from silicon-rich residue provided by the present application can remove the soluble fluorine which is not conducive to plant growth by washing the silicon-rich residue produced in the process of producing phosphogypsum, which contains plant-absorbable silicic acid and a small amount of water-soluble silicon, as well as calcium, sulfur, phosphorus, iron, potassium, magnesium and other nutrients required for plant growth. Then, the calcium-based alkaline component is added to fix fluorine. Finally, the treated silicon-rich residue is mixed with a binder to perform granulation to obtain high-quality composite silicon fertilizer. The method is simple to operate, the cost of treating silicon-rich residue is low, and the resource utilization of silicon-rich residue is realized.

[0015] Preferably, the SiO2 content in the silicon-rich residue in step (1) is 50wt%-80wt%, for example, it can be 50wt%, 60wt%, 70wt%, 75wt%, 78wt% or 80wt%, etc.

[0016] Preferably, the P2O5 content in the silicon-rich residue is 0.5wt%-10wt%, for example, it can be 0.5wt%, 1wt%, 3wt%, 5wt%, 7wt%, 9wt% or 10wt%, etc.

[0017] Preferably, the CaO content in the silicon-rich slag is in the range of 0.5wt% to 10wt%, for example, it can be 0.5wt%, 1wt%, 3wt%, 5wt%, 7wt%, 9wt% or 10wt% and the like.

[0018] Preferably, the SO3 content in the silicon-rich slag is in the range of 5wt% to 20wt%, for example, it can be 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt% or 20wt% and the like.

[0019] Preferably, the Fe2O3 content in the silicon-rich slag is in the range of 0.5wt% to 5.5wt%, for example, it can be 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt% or 5.5wt% and the like.

[0020] Preferably, the K2O content in the silicon-rich slag is in the range of 0.5wt% to 7.5wt%, for example, it can be 0.5wt%, 1wt%, 3wt%, 5wt%, 6wt%, 7wt% or 7.5wt% and the like.

[0021] Preferably, the MgO content in the silicon-rich slag is in the range of 0.01wt% to 0.5wt%, for example, it can be 0.01wt%, 0.05wt%, 0.1wt%, 0.3wt%, 0.4wt% or 0.5wt% and the like.

[0022] Preferably, the F content in the silicon-rich slag is in the range of 0.01wt% to 0.8wt%, for example, it can be 0.01wt%, 0.05wt%, 0.1wt%, 0.4wt%, 0.5wt%, 0.7wt% or 0.8wt% and the like.

[0023] Preferably, the mass ratio of the silicon-rich slag to water in step (1) is 1:(0.5 to 5), for example, it can be 1:0.5, 1:1, 1:2, 1:2.5, 1:4 or 1:5 and the like.

[0024] Preferably, the temperature of the water washing in step (1) is in the range of 40 to 80°C, for example, it can be 40°C, 45°C, 50°C, 60°C, 70°C or 80°C and the like.

[0025] Preferably, the calcium-based alkaline component in step (2) comprises any one or a combination of at least two of carbide slag, calcium hydroxide or calcium oxide, wherein a typical but non-limiting combination is a combination of carbide slag and calcium hydroxide, a combination of calcium oxide and carbide slag or a combination of calcium hydroxide and calcium oxide.

[0026] The calcium-based alkaline component preferably comprises any one or a combination of two or more of carbide slag, calcium hydroxide or calcium oxide, which has a high solubility and can combine with fluoride ions to form calcium fluoride precipitate, thereby effectively fixing the fluoride in the silicon-rich residue after water washing.

[0027] Preferably, the calcium oxide content in the calcium-based alkaline component is 60wt%-95wt%, such as 60wt%, 70wt%, 80wt%, 85wt%, 90wt% or 95wt%, etc.

[0028] Preferably, the ratio of the mass percentage of calcium in the calcium-based alkaline component to the mass percentage of fluoride in the silicon-rich residue is (1.5-2.5):1, such as 1.5:1, 1.7:1, 2:1, 2.2:1, 2.3:1 or 2.5:1, etc.

[0029] The calcium-based alkaline component preferably has a ratio of the mass percentage of calcium to the mass percentage of fluoride in the silicon-rich residue of (1.5-2.5):1, which can effectively fix the fluoride in the silicon-rich residue after water washing. If the ratio of the mass percentage of calcium in the calcium-based alkaline component to the mass percentage of fluoride in the silicon-rich residue is too small, the resulting composite silicon fertilizer still contains soluble fluoride, which is harmful to plant growth. If the ratio of the mass percentage of calcium in the calcium-based alkaline component to the mass percentage of fluoride in the silicon-rich residue is too large, the amount of the calcium-based alkaline component used is too large, the cost of processing the silicon-rich residue is high, and the soil acidity and alkalinity are affected.

[0030] Preferably, the mixing method in step (2) comprises any one or a combination of two or more of rotary mixing, stirring mixing, spiral mixing, grinding mixing or sieving mixing, and a typical but non-limiting combination is a combination of rotary mixing and stirring mixing, a combination of spiral mixing and grinding mixing, or a combination of sieving mixing and rotary mixing.

[0031] Preferably, the binder in step (3) comprises any one or a combination of two or more of water glass, polyacrylamide, superabsorbent resin, carboxymethyl starch or sodium carboxymethyl cellulose, and a typical but non-limiting combination is a combination of water glass and polyacrylamide, a combination of superabsorbent resin and carboxymethyl starch, or a combination of sodium carboxymethyl cellulose and polyacrylamide.

[0032] Preferably, the mass ratio of the silicon-rich residue after fluorine fixation treatment to the binder in step (3) is 1:(0.01-0.1), such as 1:0.01, 1:0.03, 1:0.05, 1:0.07, 1:0.09 or 1:0.1, etc.

[0033] The numerical range described in the present application not only includes the point values listed above, but also includes any point values between the above numerical ranges not listed, and the present application does not list the specific point values included in the range for the sake of brevity and simplicity.

[0034] As a preferred technical scheme of the present application, the method comprises the following steps:

[0035] (1) The silicon-rich slag is washed with water to remove soluble fluorine, according to a mass ratio of the silicon-rich slag to water of 1:(0.5-5) and a water washing temperature of 40-80 DEG C; the silicon-rich slag is produced in the production process of phosphogypsum;

[0036] The silicon-rich slag contains SiO2 at 50wt%-80wt%, P2O5 at 0.5wt%-10wt%, CaO at 0.5wt%-10wt%, SO3 at 5wt%-20wt%, Fe2O3 at 0.5wt%-5.5wt%, K2O at 0.5wt%-7.5wt%, MgO at 0.01wt%-0.5wt%, and F at 0.01wt%-0.8wt%;

[0037] (2) The water-washed silicon-rich slag is mixed with a calcium-based alkaline component containing CaO at 60wt%-95wt% to perform fluorine fixation treatment;

[0038] The calcium-based alkaline component includes any one or a combination of at least two of carbide slag, calcium hydroxide or calcium oxide; the ratio of the mass percentage of calcium in the calcium-based alkaline component to the mass percentage of fluorine in the silicon-rich slag is (1.5-2.5):1; and the mixing mode includes any one or a combination of at least two of rotary mixing, stirring mixing, spiral mixing, grinding mixing or sieving mixing;

[0039] (3) The silicon-rich slag after the fluorine fixation treatment is mixed with a binder at a mass ratio of 1:(0.01-0.1) to prepare granular composite silicon fertilizer through granulation;

[0040] The composite silicon fertilizer contains effective silicon at 25% or more, effective phosphorus at 0.2% or more, potassium at 0.3% or more, and no soluble fluorine;

[0041] The binder includes any one or a combination of at least two of water glass, polyacrylamide, superabsorbent resin, carboxymethyl starch or sodium carboxymethyl cellulose.

[0042] Compared with the prior art, the present application has at least the following beneficial effects:

[0043] The method for preparing the composite silicon fertilizer from the silicon-rich residue provided by the application removes soluble fluorine from the silicon-rich residue generated in the production process of phosphogypsum through water washing, and then adds an alkaline component to fix fluorine and avoid the release of toxic components. The prepared composite silicon fertilizer has high contents of silicon, phosphorus and potassium, realizes the resource utilization of the silicon-rich residue, improves the economy of the overall phosphogypsum purification process, and is conducive to the promotion of the phosphogypsum purification process. DETAILED DESCRIPTION

[0044] For the purpose of facilitating the understanding of the present application, the present application is illustrated by the following examples. It should be understood by those skilled in the art that the examples are only used to help understand the present application and should not be regarded as a specific limitation on the present application.

[0045] The present application is further described in detail below. However, the following examples are only simple examples of the present application and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims.

[0046] Example 1

[0047] The present example provides a method for preparing a composite silicon fertilizer from a silicon-rich residue, which comprises the following steps:

[0048] (1) The silicon-rich residue generated in the production process of phosphogypsum is water washed to remove soluble fluorine, with a mass ratio of the silicon-rich residue to water of 1:5 and a water washing temperature of 50℃;

[0049] The silicon-rich residue has a SiO2 content of 50wt%, a P2O5 content of 10wt%, a CaO content of 10wt%, a SO3 content of 20wt%, a Fe2O3 content of 0.5wt%, a K2O content of 7.5wt%, a MgO content of 0.01wt% and a F content of 0.6wt%;

[0050] (2) The water-washed silicon-rich residue is mixed with calcium oxide-containing calcium carbide slag with a calcium content of 60wt% to perform fluorine fixation treatment;

[0051] The ratio of the mass percentage content of calcium in the calcium carbide slag to the mass percentage content of fluorine in the silicon-rich residue is 1.5:1;

[0052] (3) The fluorine-fixed silicon-rich residue is mixed with a binder at a mass ratio of 1:0.1, and granulated to prepare a granular composite silicon fertilizer;

[0053] The binder is composed of 20wt% water glass, 20wt% polyacrylamide, 5wt% superabsorbent resin, 25wt% carboxymethyl starch and 30wt% carboxymethyl cellulose sodium.

[0054] Example 2

[0055] The embodiment provides a method for preparing composite silicon fertilizer from silicon-rich slag, and the method comprises the following steps:

[0056] (1) The silicon-rich slag is washed with water at a mass ratio of 1:0.5 and a water washing temperature of 80 DEG C, so as to remove soluble fluorine; the silicon-rich slag is produced in the production process of phosphogypsum;

[0057] The silicon-rich slag contains 80 wt% of SiO2, 0.5 wt% of P2O5, 0.5 wt% of CaO, 5 wt% of SO3, 5.5 wt% of Fe2O3, 0.5 wt% of K2O, 0.5 wt% of MgO and 0.01 wt% of F;

[0058] (2) The silicon-rich slag after water washing is mixed with calcium hydroxide containing 70 wt% of calcium oxide to perform fluorine fixation treatment;

[0059] The ratio of the mass percentage of calcium in the calcium hydroxide to the mass percentage of fluorine in the silicon-rich slag is 2.5:1; the mixing mode is stirring mixing and spiral mixing;

[0060] (3) The silicon-rich slag after fluorine fixation treatment is mixed with a binder at a mass ratio of 1:0.01, and granulation is performed to prepare granular composite silicon fertilizer;

[0061] The binder is composed of 20% water glass, 20% polyacrylamide, 5% superabsorbent resin, 25% carboxymethyl starch and 30% carboxymethyl cellulose sodium.

[0062] Embodiment 3

[0063] The embodiment provides a method for preparing composite silicon fertilizer from silicon-rich slag, and the method comprises the following steps:

[0064] (1) The silicon-rich slag is washed with water at a mass ratio of 1:3 and a water washing temperature of 40 DEG C, so as to remove soluble fluorine; the silicon-rich slag is produced in the production process of phosphogypsum;

[0065] The silicon-rich slag contains 60 wt% of SiO2, 7 wt% of P2O5, 5 wt% of CaO, 12 wt% of SO3, 3 wt% of Fe2O3, 4 wt% of K2O, 0.1 wt% of MgO and 0.8 wt% of F;

[0066] (2) The silicon-rich slag after water washing is mixed with calcium oxide containing 95 wt% of calcium oxide to perform fluorine fixation treatment;

[0067] The ratio of the mass percentage content of calcium in the calcium oxide to the mass percentage content of fluorine in the silicon-rich slag is 2:1; the mixing method is grinding and mixing and sieving;

[0068] (3) The silicon-rich slag after the fluorine fixation treatment is mixed with the binder at a mass ratio of 1:0.06, and granulated to prepare a granular composite silicon fertilizer.

[0069] The binder is composed of 20% water glass, 20% polyacrylamide, 5% superabsorbent resin, 25% carboxymethyl starch, and 30% carboxymethyl cellulose sodium, by mass percentage.

[0070] Example 4

[0071] The present example provides a method for preparing a composite silicon fertilizer from a silicon-rich slag, which comprises the same conditions as in Example 1 except that the ratio of the mass percentage content of calcium in the calcium oxide to the mass percentage content of fluorine in the silicon-rich slag in step (2) is 1:1.

[0072] Example 5

[0073] The present example provides a method for preparing a composite silicon fertilizer from a silicon-rich slag, which comprises the same conditions as in Example 1 except that the ratio of the mass percentage content of calcium in the calcium oxide to the mass percentage content of fluorine in the silicon-rich slag in step (2) is 3:1.

[0074] Example 6

[0075] The present example provides a method for preparing a composite silicon fertilizer from a silicon-rich slag, which comprises the same conditions as in Example 1 except that the calcium oxide in step (2) is replaced by calcium carbonate.

[0076] Comparative Example 1

[0077] The present comparative example provides a method for preparing a composite silicon fertilizer from a silicon-rich slag, which comprises the same conditions as in Example 1 except that the water washing in step (1) is not performed.

[0078] The composite silicon fertilizer products obtained in the above examples and comparative examples are characterized by the following methods:

[0079] The effective silicon content in the product is determined according to the national standard "NY / T 797-2004 Silicon Fertilizer".

[0080] The effective phosphorus and potassium contents in the product are determined according to the national standard "GB / T 15063-2020 Compound Fertilizer".

[0081] The F content in the product is determined by the method of "GB / T 21057-2007 General Method for Determination of Fluorine Content in Inorganic Chemical Products Ion Selective Electrode Method".

[0082] The results of each index in the above examples and comparative examples are listed in Table 1.

[0083] Table 1

[0084] Item Effective silicon content / % Effective phosphorus content / % Potassium content / % Soluble fluorine content / % Example 1 25 6.3 5.1 not detected Example 2 38 0.2 0.3 not detected Example 3 31 4.5 2.7 not detected Example 4 24 6.4 5.0 0.23 Example 5 21 5.5 4.7 not detected Example 6 26 6.5 5.0 0.42 Comparative Example 1 29 7.0 6.5 0.37

[0085] From Table 1, it can be seen that:

[0086] (1) As can be seen from Examples 1-3, the method for preparing the composite silicon fertilizer from the silicon-rich slag provided by the application is simple to operate, and the composite silicon fertilizer prepared has high contents of effective silicon, effective phosphorus and potassium, and does not contain soluble fluorine which is harmful to plant growth;

[0087] (2) As can be seen from Example 1 and Examples 4-5, the ratio of the mass percentage of calcium in the calcium carbide slag to the mass percentage of fluorine in the silicon-rich slag in Example 4 is small, and soluble fluorine still exists in the final obtained composite silicon fertilizer, which is not conducive to plant growth; the ratio of the mass percentage of calcium in the calcium-based alkaline component to the mass percentage of fluorine in the silicon-rich slag in Example 5 is too large, the use amount of the calcium-based alkaline component is too large, the cost of the silicon-rich slag treatment is high, and the soil acidity and alkalinity are also affected;

[0088] (3) As can be seen from Example 1 and Example 6, calcium carbonate is used in Example 6, which has low solubility and cannot combine with fluorine ions to form calcium fluoride precipitate, so it cannot completely fix fluorine, and the soluble fluorine content in the final obtained composite silicon fertilizer is 0.42%, which is not conducive to plant growth, but the contents of effective silicon, effective phosphorus and potassium in the composite silicon fertilizer are equivalent to those in Example 1;

[0089] (4) As can be seen from Example 1 and Comparative Example 1, the soluble fluorine in the silicon-rich slag cannot be effectively removed in Comparative Example 1 because the silicon-rich slag is not washed, and the soluble fluorine in the composite silicon fertilizer cannot be completely fixed because the alkaline component is added subsequently, and the soluble fluorine content in the composite silicon fertilizer is 0.37%; because the silicon-rich slag is not washed, the contents of effective silicon, effective phosphorus and potassium in the composite silicon fertilizer in Comparative Example 1 are slightly higher than those in Example 1.

[0090] In summary, the method for preparing the composite silicon fertilizer from the silicon-rich slag provided by the application can fix fluorine by washing the silicon-rich slag produced in the production process of phosphogypsum and adding an alkaline component, so that the final obtained composite silicon fertilizer does not contain soluble fluorine which is not conducive to plant growth, and the contents of silicon, phosphorus and potassium in the composite silicon fertilizer are high, the resource utilization of the silicon-rich slag is realized, the economy of the overall phosphogypsum purification process is improved, and the method is suitable for large-scale promotion.

[0091] The applicant states that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and it should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought out by those skilled in the art, and all of them fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a complex silicon fertilizer free of soluble fluorine from a silicon-rich slag, characterized in that, The method comprises the following steps: (1) washing the silicon-rich residue with water to remove soluble fluorine; the silicon-rich residue is produced in the production process of phosphogypsum; (2) mixing the water-washed silicon-rich residue with a calcium-based alkaline component to perform fluorine fixation treatment; (3) mixing the fluorine fixation treated silicon-rich residue with a binder to prepare granular composite silicon fertilizer through granulation; The effective silicon content in the composite silicon fertilizer is more than 25%, the effective phosphorus content is more than 0.2%, the potassium content is more than 0.3%, and the composite silicon fertilizer does not contain soluble fluorine; In step (1), the SiO2 content in the silicon-rich residue is 50wt%-80wt%; In step (1), the P2O5 content in the silicon-rich residue is 0.5wt%-10wt%; In step (1), the F content in the silicon-rich residue is 0.01wt%-0.8wt%; In step (1), the mass ratio of the silicon-rich residue to water is 1:(0.5-5); In step (2), the mass percentage ratio of calcium in the calcium-based alkaline component to fluorine in the silicon-rich residue is (1.5-2.5):1; In step (2), the calcium-based alkaline component comprises any one or a combination of at least two of carbide slag, calcium hydroxide or calcium oxide; In the calcium-based alkaline component, the content of calcium oxide is 60wt%-95wt%.

2. The method of claim 1, wherein, In step (1), the CaO content in the silicon-rich residue is 0.5wt%-10wt%.

3. The method of claim 1, wherein, In step (1), the SO3 content in the silicon-rich residue is 5wt%-20wt%.

4. The method of claim 1, wherein, In step (1), the Fe2O3 content in the silicon-rich residue is 0.5wt%-5.5wt%.

5. The method of claim 1, wherein, In step (1), the K2O content in the silicon-rich residue is 0.5wt%-7.5wt%.

6. The method of claim 1, wherein, In step (1), the MgO content in the silicon-rich residue is 0.01wt%-0.5wt%.

7. The method according to any one of claims 1 to 6, characterized in that, In step (1), the water washing temperature is 40-80℃.

8. The method according to any one of claims 1 to 6, characterized in that, In step (2), the mixing mode comprises any one or a combination of at least two of rotary mixing, stirring mixing, spiral mixing, grinding mixing or sieving mixing.

9. The method according to any one of claims 1 to 6, characterized in that, In step (3), the binder comprises any one or a combination of at least two of water glass, polyacrylamide, superabsorbent resin, carboxymethyl starch or sodium carboxymethyl cellulose.

10. The method according to any one of claims 1 to 6, characterized in that, In step (3), the mass ratio of the fluorine fixation treated silicon-rich residue to the binder is 1:(0.01-0.1).

11. The method according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: (1) washing the silicon-rich residue with water to remove soluble fluorine; the silicon-rich residue is produced in the production process of phosphogypsum; In the silicon-rich residue, the SiO2 content is 50wt%-80wt%, the P2O5 content is 0.5wt%-10wt%, the CaO content is 0.5wt%-10wt%, the SO3 content is 5wt%-20wt%, the Fe2O3 content is 0.5wt%-5.5wt%, the K2O content is 0.5wt%-7.5wt%, the MgO content is 0.01wt%-0.5wt%, and the F content is 0.01wt%-0.8wt%; (2) mixing the washed silicon-rich residue with a calcium-based alkaline component having a calcium oxide content of 60wt%-95wt% to perform a fluorine fixation treatment; The calcium-based alkaline component includes any one or a combination of at least two of calcium carbide slag, calcium hydroxide or calcium oxide; the ratio of the mass percentage of calcium in the calcium-based alkaline component to the mass percentage of fluorine in the silicon-rich residue is (1.5-2.5):1; the mixing mode includes any one or a combination of at least two of rotary mixing, stirring mixing, spiral mixing, grinding mixing or sieving mixing; (3) mixing the silicon-rich residue after the fluorine fixation treatment with a binder at a mass ratio of 1:(0.01-0.1) to prepare granular composite silicon fertilizer through granulation; The effective silicon content in the composite silicon fertilizer is more than 25%, the effective phosphorus content is more than 0.2%, the potassium content is more than 0.3% and the composite silicon fertilizer does not contain soluble fluorine; The binder includes any one or a combination of at least two of water glass, polyacrylamide, superabsorbent resin, carboxymethyl starch or sodium carboxymethyl cellulose.