Method for preparing silicon-containing compound fertilizer by extracting aluminum residue from fly ash, and silicon-containing compound fertilizer

Abstract

The present invention provides a method for preparing silicon-containing compound fertilizer from aluminum-extracted residue from fly ash, and silicon-containing compound fertilizer. The method comprises the following steps: washing the aluminum-extracted residue from fly ash in sequence, filtering it under positive pressure, obtaining an intermediate residue; mixing the intermediate residue with an activator, introducing steam into the mixture for activation reaction, and obtaining an activated material; grinding, granulating, screening, and drying the activated material in sequence to obtain a silicon-containing compound fertilizer; wherein the activator is selected from one or more of a potassium-based activator, a magnesium-based activator, or a calcium-based activator. The method for preparing silicon-containing compound fertilizer of the present invention is simple to operate, has low production cost, and the prepared silicon-containing compound fertilizer has a high content of effective ingredients and strong activity of the effective ingredients. It can effectively reduce chloride ions and heavy metal ions in the silicon-containing compound fertilizer. When used as a fertilizer, it can be beneficial to regulating the soil and significantly increase yield.

Description

Technical Field

[0001] The present invention relates to the field of agricultural fertilizers, and in particular to a method for preparing silicon-containing compound fertilizer from fly ash aluminum extraction residue and the silicon-containing compound fertilizer. Background Art

[0002] Silicon is an essential secondary nutrient for crop growth and is ranked by the international soil science community as the fourth most important element after nitrogen, phosphorus, and potassium. It significantly improves crop resistance to lodging, disease, and drought. Furthermore, silicon-containing compound fertilizers (such as silicon-calcium-potassium-magnesium compound fertilizers) can be used as soil conditioners, effectively deactivating heavy metals and reducing the adverse effects of toxic and harmful elements in the soil on crops. They have become highly effective, high-quality fertilizers for green, ecological agriculture. According to statistics, silicon-deficient soils account for approximately 50% of my country's arable land, and this area is gradually expanding. The Yangtze River Basin is particularly severely deficient, with the proportion reaching 70%. For example, rice is cultivated annually on over 33.33 million hectares in my country. If silicon-containing compound fertilizers were applied to all of them, a 10% increase in yield could result in an additional 1 million tons of rice per year. Therefore, promoting the production and use of silicon-containing compound fertilizers has significant social and economic benefits.

[0003] Fly ash is a volcanic ash mixture formed by high-temperature combustion of pulverized coal. The pulverized coal burns in a high-temperature suspended state in the furnace, with the combustible portion burned out in the furnace. Most of the inorganic components are mixed in the high-temperature flue gas and discharged. The particulate matter captured by the dust collector is called fly ash. Fly ash contains harmful substances, and common disposal methods include landfill or incineration. These methods occupy land resources and harm the ecological environment. If fly ash can be recycled, environmental pollution can be reduced and resource utilization can be improved. Fly ash mainly contains silicon dioxide (SiO2), aluminum oxide (Al2O3), and iron oxide (Fe2O3). After high-aluminum fly ash is dissolved in hydrochloric acid to extract aluminum oxide, the SiO2 content of the residue is about 70%, which can be used to prepare silicon fertilizer.

[0004] Although the prior art has a method for preparing silicon fertilizer using the residue after aluminum extraction from fly ash, fly ash, hydrochloric acid, and a grinding aid are mixed evenly and then ground and dispersed, and the material is then filtered and separated to obtain a fly ash aluminum extraction filter residue, and then the fly ash aluminum extraction residue is mixed with an activator and subjected to high-temperature roasting, crushing and granulation to obtain silicon fertilizer. However, the silicon fertilizer prepared by the above method has the following problems: 1. The effective silicon content in the silicon fertilizer is low and the silicon activity ability is low. 2. The fly ash residue after hydrochloric acid treatment still contains a small amount of heavy metal substances and chlorine elements, and the prior art has a low efficiency in removing these heavy metal ions and chloride ions. These substances remain in the silicon fertilizer and will affect the growth of crops. 3. The activation process consumes a lot of energy.

[0005] In order to solve the above problems, the present application provides a new method for preparing silicon fertilizer from fly ash aluminum extraction residue. Summary of the Invention

[0006] The main purpose of the present invention is to provide a method for preparing silicon-containing compound fertilizer from fly ash aluminum extraction residue and silicon-containing compound fertilizer, so as to solve the problems of low effective silicon content, inability to effectively remove heavy metals and chlorides, and high energy consumption in the activation process when preparing silicon fertilizer in the prior art.

[0007] To achieve the above-mentioned object, according to one aspect of the present invention, there is provided a method for preparing silicon-containing compound fertilizer from aluminum-extracted residue from fly ash, comprising the following steps: washing and positive-pressure filtering the aluminum-extracted residue from fly ash in sequence to obtain an intermediate residue; mixing the intermediate residue with an activator and introducing steam into the mixture for activation reaction to obtain an activated material; and grinding, granulating, sieving and drying the activated material in sequence to obtain a silicon-containing compound fertilizer; wherein the activator is selected from one or more of a potassium-based activator, a magnesium-based activator or a calcium-based activator.

[0008] Furthermore, the detergent used for washing is water, and the weight ratio of the fly ash aluminum extraction residue to water during the washing process is 1:3 to 8.

[0009] Furthermore, the pressure of the positive pressure filtration is 0.5 to 3.0 MPa.

[0010] Furthermore, the activator is a mixture of a potassium-based activator, a magnesium-based activator and a calcium-based activator, and the weight ratio of the potassium-based activator, the magnesium-based activator and the calcium-based activator is 1:(0.05-0.5):(0.1-1.0):(0.3-1.5).

[0011] Furthermore, the potassium-based activator is selected from potassium carbonate and / or potassium hydroxide.

[0012] Furthermore, the magnesium-based activator is selected from magnesium carbonate and / or magnesium hydroxide.

[0013] Furthermore, the calcium-based activator is selected from one or more of calcium hydroxide, calcium carbonate or calcium oxide.

[0014] Furthermore, the weight ratio of the intermediate residue to the potassium-based activator, the magnesium-based activator, and the calcium-based activator is 1:(0.1-0.3):(0.2-0.6):(0.5-1.0).

[0015] Furthermore, the activation reaction temperature is 200-600° C., and the activation time is 30-120 min.

[0016] Furthermore, a binder is added to the system during the granulation process, and the amount of the binder is 0.01 to 0.05 g per gram of silicon-containing compound fertilizer.

[0017] Furthermore, the binder is selected from α-starch.

[0018] Furthermore, water is added to the system during the grinding process, and the weight ratio of water to the activated material during the grinding process is 1:1-3.

[0019] Furthermore, the particle size of the sieved material is 1 to 4 mm.

[0020] Furthermore, the drying temperature is 70-120° C., and the drying time is 30-150 min.

[0021] Furthermore, the fly ash aluminum extraction residue includes 55-75wt% SiO2, 10-20wt% Al2O3, 7-12wt% residual carbon, 0.5-2.5wt% chloride and other inevitable impurities.

[0022] In order to achieve the above object, according to one aspect of the present invention, a silicon-containing compound fertilizer is provided, which is prepared by the above-mentioned method for preparing silicon-containing compound fertilizer by extracting aluminum residue from fly ash.

[0023] The technical solution of the present invention is to wash and positively filter the fly ash aluminum extraction residue first, thereby removing soluble heavy metals and their compounds (CrCl3, PbCl2, CdCl2, etc.) and soluble chlorides (AlCl3, FeCl3, etc.) remaining in the fly ash aluminum extraction residue through washing and positive pressure filtration, thereby effectively reducing the content of heavy metal ions and chloride ions in the silicon fertilizer produced subsequently. The intermediate residue after the heavy metal ions and chloride ions are then mixed with an activator and an activation reaction is carried out under the condition of steam. Compared with the existing activation process using high-temperature roasting, the steam activation process can increase the humidity of the activated material, which can participate in the activation reaction process, improve the activation efficiency, and help increase the content and activity of effective silicon in the silicon fertilizer. The energy consumption of the activation process is also lower, which is conducive to reducing production costs. Finally, the activated material is ground, granulated, sieved, and dried to obtain a silicon-containing composite fertilizer. The silicon-containing composite fertilizer produced by the present invention has a high effective silicon content of more than 20%, and the strength of the silicon-containing composite fertilizer is greater than 10N. The method for preparing the silicon-containing compound fertilizer of the present invention is simple to operate and has low production costs. The prepared silicon-containing compound fertilizer has a high content of active ingredients and strong activity of the active ingredients. It can effectively reduce chloride ions and heavy metal ions in the silicon-containing compound fertilizer. When used as a fertilizer, it can be beneficial for soil conditioning, and plants can quickly absorb and utilize it, significantly increasing yield. At the same time, it can also improve the comprehensive utilization rate of aluminum extracted from fly ash and enhance the economic benefits of extracting alumina from fly ash. It has obvious economic advantages, low coal consumption, energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 A schematic diagram of a process for preparing silicon-containing compound fertilizer from fly ash aluminum residue according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0027] As described in the background technology section of this application, the existing methods for preparing silicon fertilizers have the problems of low effective silicon content, inability to effectively remove heavy metals and chlorides, and high energy consumption during the activation process. In order to solve this problem, this application provides a method for preparing silicon-containing compound fertilizers from fly ash aluminum residues, such as Figure 1 As shown, the fly ash aluminum extraction residue is washed and positively filtered in sequence to obtain an intermediate residue; the intermediate residue is mixed with an activator and steam is introduced into the mixture for activation reaction to obtain an activated material; the activated material is ground, granulated, sieved and dried in sequence to obtain a silicon-containing compound fertilizer; wherein the activator is selected from one or more of a potassium-based activator, a magnesium-based activator or a calcium-based activator.

[0028] The present invention first washes and positively filters the fly ash aluminum extraction residue to remove soluble heavy metals and their compounds (CrCl3, PbCl2, CdCl2, etc.) and soluble chlorides (AlCl3, FeCl3, etc.) remaining in the fly ash aluminum extraction residue through washing and positive pressure filtration, thereby effectively reducing the content of heavy metal ions and chloride ions in the silicon fertilizer produced subsequently. The intermediate residue from which the heavy metal ions and chloride ions have been removed is then mixed with an activator and subjected to an activation reaction under conditions where steam is introduced. Compared to the existing activation process using high-temperature roasting, the steam activation process can increase the humidity of the activated material, which can participate in the activation reaction process, improve the activation efficiency, and help increase the content and activity of effective silicon in the silicon fertilizer. The activation process also consumes less energy, which is beneficial for reducing production costs. Finally, the activated material is ground, granulated, sieved, and dried to obtain a silicon-containing composite fertilizer. The silicon-containing composite fertilizer produced by the present invention has a high effective silicon content of more than 20%, and the strength of the silicon-containing composite fertilizer is greater than 10N.

[0029] In summary, the method for preparing silicon-containing compound fertilizer of the present invention is simple to operate, has low production costs, and the prepared silicon-containing compound fertilizer has a high content of active ingredients and strong activity of the active ingredients. It can effectively reduce chloride ions and heavy metal ions in the silicon-containing compound fertilizer. When used as a fertilizer, it can be beneficial for soil conditioning, and plants absorb and utilize it quickly, thereby significantly increasing yield. At the same time, it can also improve the comprehensive utilization rate of aluminum extracted from fly ash and improve the economic benefits of extracting alumina from fly ash. It has obvious economic advantages, low coal consumption, energy saving and environmental protection.

[0030] It should be further noted that the fly ash aluminum extraction residue of the present invention comprises 55-75 wt% SiO2, 10-20 wt% Al2O3, 7-12 wt% residual carbon, 0.5-2.5 wt% chlorides (e.g., AlCl3, FeCl3, etc.), and other unavoidable impurities. Among the heavy metals, the Cr content is 50-100 gm / kg, the As content is 5-15 gm / kg, the Cd content is 3-7 gm / kg, the Pb content is 60-150 gm / kg, and the Hg content is 3-9 gm / kg.

[0031] After washing and positive pressure filtration, the intermediate residue contains 55-75 wt% SiO2, 6-16 wt% Al2O3, 8-13 wt% residual carbon, 0.05-0.5 wt% chloride, and other unavoidable impurities. Among the heavy metals, the Cr content is 20-50 gm / kg, the As content is 1.0-5.0 gm / kg, the Cd content is 0.1-2.0 gm / kg, the Pb content is 10-40 gm / kg, and the Hg content is 1.0-5.0 gm / kg.

[0032] In order to further improve the removal efficiency of soluble heavy metal chlorides in silicon-containing compound fertilizers, the washing detergent used is water, and the weight ratio of fly ash aluminum extraction residue to water during the washing process is 1:3 to 8. Preferably, the positive pressure filtration pressure is 0.5 to 3.0 MPa, including but not limited to 0.5 MPa, 0.8 MPa, 1.0 MPa, 1.2 MPa, 1.4 MPa, 1.5 MPa, 1.8 MPa, 2.0 MPa, 2.2 MPa, 2.4 MPa, 2.6 MPa, 2.8 MPa, and 3.0 MPa.

[0033] In a preferred embodiment, the activator is a mixture of a potassium activator, a magnesium activator and a calcium activator, and the weight ratio of the intermediate residue to the potassium activator, the magnesium activator and the calcium activator is 1: (0.05-0.5): (0.1-0.1): (0.3-1.5). In order to further optimize the regulating ability of the silicon-containing compound fertilizer on the soil and improve soil fertility, the activator of the present invention is selected from an activator mixture containing nutrients such as potassium, magnesium and calcium, which has a better effect on promoting the increase in crop yield. At the same time, the present invention controls the ratio of the intermediate residue to the activator containing various nutrients. It can make the effective potassium content of the silicon-containing compound fertilizer greater than 3%, the effective magnesium content greater than 2%, and the effective calcium content greater than 20% while maintaining a higher effective silicon content, thereby broadening the application scenarios of the silicon-containing compound fertilizer of the present invention, making the yield increase more obvious, and the added value of the product higher. More preferably, the weight ratio of the intermediate residue to the potassium-based activator, the magnesium-based activator, and the calcium-based activator is 1:(0.1-0.3):(0.2-0.6):(0.5-1.0).

[0034] In order to further improve the activity of nutrient elements in silicon-containing compound fertilizers, in some optional embodiments, the potassium activator is selected from potassium carbonate and / or potassium hydroxide; the magnesium activator is selected from magnesium carbonate and / or magnesium hydroxide; and the calcium activator is selected from one or more of calcium hydroxide, calcium carbonate or calcium oxide.

[0035] In a preferred embodiment, the activation reaction temperature is 200-600°C, and the activation time is 30-120 min. The activation reaction temperature includes but is not limited to 200°C, 300°C, 400°C, 500°C and 600°C; the activation time includes but is not limited to 30 min, 40 min, 60 min, 80 min, 100 min, and 120 min. The present invention controls the activation reaction temperature and time within the above ranges based on the following considerations: when the activation reaction temperature is too low, the time is too short, resulting in insufficient activation and low content of effective components; when the activation reaction temperature is too high, the time is too long, resulting in excessive energy consumption and low economic benefits.

[0036] In a preferred embodiment, the fly ash aluminum extraction residue and an activator are steam activated in a tube furnace at a steam rate of 0.5 to 2.0 L / h. Steam rates include, but are not limited to, 0.5 L / h, 0.8 L / h, 1.0 L / h, 1.2 L / h, 1.4 L / h, 1.6 L / h, 1.8 L / h, and 2.0 L / h. The present invention utilizes this method to activate silicon in the fly ash aluminum extraction residue, resulting in higher activation efficiency and greater effective silicon activity.

[0037] To further enhance the strength of the silicon-containing compound fertilizer, a binder is added to the system during the granulation process, with the amount of the binder being 0.01 to 0.05 g per gram of the silicon-containing compound fertilizer. Preferably, the binder is selected from α-starch. Furthermore, preferably, water mist is sprayed during the granulation process, with the amount of the water mist being 0.2 to 0.4 g per gram of the silicon-containing compound fertilizer.

[0038] In a preferred embodiment, water is added to the system during the grinding process, and the weight ratio of water to activated material during the grinding process is 1:1 to 3, including but not limited to 1:1, 1:2, and 1:3. The addition of water during the grinding process of the present invention is to facilitate the molding of the silicon-containing compound fertilizer into a block-shaped raw material, thereby reducing dust during the subsequent activation process.

[0039] In a preferred embodiment, the particle size of the sieved material is 1 to 4 mm. The present invention controls the particle size within this range based on the following considerations: excessively high particle sizes can slow the slow-release effect of the active ingredients in the silicon fertilizer; while excessively low particle sizes can lead to dispersion and loss during fertilization. To further increase yield and conserve resources, when the particle size is less than 1 mm and greater than 4 mm, the material returns to the granulation step for further comminution and pelletization.

[0040] In order to reduce the moisture content of the product and improve the stability and shelf life of the silicon-containing compound fertilizer product, the drying temperature is 70-120°C and the drying time is 30-150 minutes.

[0041] The present invention also provides a silicon-containing compound fertilizer, which is prepared by the method for preparing the silicon-containing compound fertilizer by extracting aluminum residue from fly ash as mentioned above.

[0042] Based on the above reasons, the effective silicon content of the silicon-containing compound fertilizer of the present invention is relatively high, reaching more than 20%, and the strength of the silicon-containing compound fertilizer is greater than 10N.

[0043] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0044] In the following examples and comparative examples, fly ash was obtained from the residue of alumina extraction from fly ash in Inner Mongolia. The average particle size of the fly ash aluminum extraction residue was 43 μm. The heavy metal content was 63 gm / kg Cr, 10 gm / kg As, 9 gm / kg Cd, 89 gm / kg Pb, and 5 gm / kg Hg. The main composition is shown in Table 1.

[0045] Table 1 Composition of fly ash aluminum extraction residue (wt%)

[0046] <![CDATA[Na2O]]> MgO <![CDATA[Al2O3]]> <![CDATA[SiO2]]> <![CDATA[P2O5]]> <![CDATA[Cl - ]]> <![CDATA[SO3]]> <![CDATA[K2O]]> CaO <![CDATA[TiO2]]> <![CDATA[Fe2O3]]> C 0.13 0.06 17.26 67.28 0.1 2.2 0.41 0.49 0.23 4.12 0.46 7.25

[0047] Example 1

[0048] The preparation process of silicon-containing compound fertilizer is as follows:

[0049] (1) Weigh 1000 g of fly ash aluminum extraction residue, place it in a positive pressure filter, add 3000 g of water into the positive pressure filter, and then pass compressed air into the positive pressure filter at a pressure of 0.5 MPa to pressure wash the aluminum extraction residue to obtain an intermediate residue;

[0050] (2) mixing the intermediate residue with potassium carbonate, magnesium carbonate, and calcium hydroxide in a weight ratio of 1:0.1:0.2:0.5, and then adding water in a weight ratio of 1:1 to the dry powder (intermediate residue with potassium carbonate, magnesium carbonate, and calcium hydroxide), and wet mixing to prepare a block raw material;

[0051] (3) placing the bulk raw material obtained in step (2) into a tubular furnace and introducing 1.0 L / h of 200° C. steam for activation to obtain an activated material. During the activation process, the activation temperature is 200° C. and the activation time is 30 min;

[0052] (4) transferring the activated material obtained in step (3) to a high-speed granulator for pulverization, then adding α-starch to the high-speed granulator for stirring and mixing, and spraying water mist during the mixing process for granulation. The amount of α-starch (pregelatinized starch (α-starch) produced by Hebei Yanxing Chemical Co., Ltd.) used is 0.01 g per gram of silicon-containing compound fertilizer, and the amount of water mist sprayed is 0.2 g;

[0053] (5) Screening the particles obtained in step (4) to obtain particles with a particle size of 1 to 3 mm, and returning the particles with a particle size less than 1 mm and greater than 3 mm to step (4) for granulation;

[0054] (6) Drying the sieved material obtained in step (5) at a drying temperature of 70° C. for 30 min to obtain a silicon-containing compound fertilizer product.

[0055] Example 2

[0056] (1) Weigh 1000 g of fly ash aluminum extraction residue and place it in a positive pressure filter. Add 5000 g of water to the positive pressure filter, then pass compressed air into the positive pressure filter at a pressure of 1.0 MPa to pressure-wash the aluminum extraction residue to obtain an intermediate residue.

[0057] (2) mixing the intermediate residue obtained in step (1) with potassium carbonate, magnesium carbonate and calcium hydroxide in a weight ratio of 1:0.1:0.2:0.5, and then adding water in a weight ratio of 1:1 to the dry powder (intermediate residue and potassium carbonate, magnesium carbonate and calcium hydroxide), and wet mixing to prepare a block raw material;

[0058] (3) placing the bulk raw material obtained in step (2) into a tubular furnace and introducing 1.0 L / h of 200° C. steam for activation to obtain an activated material. During the activation process, the activation temperature is 200° C. and the activation time is 30 min;

[0059] (4) transferring the activated material obtained in step (3) to a high-speed granulator for pulverization, then adding α-starch to the high-speed granulator for stirring and mixing, and spraying water mist during the mixing process for granulation. The amount of α-starch used is 0.01 g per gram of silicon-containing compound fertilizer, and the amount of water mist sprayed is 0.2 g;

[0060] (5) Screening the particles obtained in step (4) to obtain particles with a particle size of 1 to 3 mm, and returning the particles with a particle size less than 1 mm and greater than 3 mm to step (4) for granulation;

[0061] (6) Drying the sieved material obtained in step (5) at a drying temperature of 70° C. for 30 min to obtain a silicon-containing compound fertilizer product.

[0062] Example 3

[0063] The only difference from the preparation method of Example 2 is that the weight ratio of the intermediate residue to potassium carbonate, magnesium carbonate and calcium hydroxide is 1:0.2:0.3:0.5, the activation temperature is 300° C., and the activation time is 30 min.

[0064] Example 4

[0065] The only difference from the preparation method of Example 2 is that the weight ratio of the intermediate residue to potassium carbonate, magnesium carbonate and calcium hydroxide is 1:0.2:0.3:1.0, the activation temperature is 300° C., and the activation time is 30 min.

[0066] Example 5

[0067] The only difference from the preparation method of Example 2 is that the activation temperature is 500° C. and the activation time is 60 min.

[0068] Example 6

[0069] The only difference from the preparation method of Example 5 is that in step (4), during the granulation process of the activated material, the amount of α-starch (pregelatinized starch (α-starch) produced by Hebei Yanxing Chemical Co., Ltd.) used is 0.05 g per gram of the weight of the silicon-containing compound fertilizer, and the amount of water mist sprayed is 0.4 g.

[0070] Example 7

[0071] The preparation method differs from the preparation method of Example 2 only in that the activator does not include a potassium-based activator, does not contain potassium carbonate, and the weight ratio of the intermediate residue to magnesium carbonate and calcium hydroxide is 1:0.2:0.5.

[0072] Example 8

[0073] The preparation method differs from the preparation method of Example 2 only in that the activator does not include a magnesium-based activator, does not contain magnesium carbonate, and the weight ratio of the intermediate residue to potassium carbonate and calcium hydroxide is 1:0.1:0.5.

[0074] Comparative Example 1

[0075] The only difference from the preparation method of Example 2 is that the fly ash aluminum extraction residue is not treated in step (1), and the fly ash aluminum extraction residue is directly activated with the activator.

[0076] Comparative Example 2

[0077] The preparation method of Example 2 is different only in that the intermediate residue and the activator are not activated by steam activation, but are activated by high-temperature calcination at 1200°C. The specific process is as follows: the intermediate residue is mixed with potassium carbonate, magnesium carbonate and calcium hydroxide in a ratio of 1:0.1:0.2:0.5, and then water is added in a weight ratio of 1:1 to the dry powder (intermediate residue and potassium carbonate, magnesium carbonate and calcium hydroxide) to wet mix to form a block raw material; the block raw material is then placed in a rotary kiln and calcined at high temperature, wherein the calcination temperature is 1200°C and the calcination time is 60 min.

[0078] Performance Testing: The effective nutrient content, composition, and strength of the silicon-containing compound fertilizers in the above examples and comparative examples were tested in accordance with the national standard GB / T 36207-2018, "Silicon-Calcium-Potassium-Magnesium Compound Fertilizer." The fertilizer strength was tested using a particle strength tester, the heavy metal content of the silicon-containing compound fertilizer products was tested using the ICP method, and the chloride content of the silicon-containing compound fertilizer products was tested using potentiometric titration. Specific test results are shown in Table 2.

[0079] Table 2

[0080]

[0081] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing silicon-containing compound fertilizer from fly ash aluminum residue, characterized in that: The following steps are involved: The fly ash aluminum extraction residue is sequentially washed and positive pressure filtered to obtain an intermediate residue; The intermediate residue is mixed with an activator and steam is introduced into the mixture for activation reaction to obtain an activated material; Grinding, granulating, screening and drying the activated material in sequence to obtain the silicon-containing compound fertilizer; in, The activator is a mixture of a potassium-based activator, a magnesium-based activator, and a calcium-based activator, and the weight ratio of the intermediate residue to the potassium-based activator, the magnesium-based activator, and the calcium-based activator is 1:(0.05-0.5):(0.1-1.0):(0.3-1.5); The potassium activator is selected from potassium carbonate and / or potassium hydroxide; The magnesium activator is selected from magnesium carbonate and / or magnesium hydroxide; The activation reaction temperature is 200-600° C., and the activation time is 30-120 minutes.

2. The method for preparing silicon-containing compound fertilizer from fly ash aluminum residue according to claim 1, characterized in that: The washing agent used in the washing is water, and the weight ratio of the fly ash aluminum extraction residue to water during the washing process is 1:3~8.

3. The method for preparing silicon-containing composite fertilizer from fly ash aluminum residue according to claim 2, characterized in that: The pressure of the positive pressure filtration is 0.5~3.0Mpa.

4. The method for preparing silicon-containing composite fertilizer from fly ash aluminum residue according to claim 1 or 2, characterized in that: The calcium-based activator is selected from one or more of calcium hydroxide, calcium carbonate or calcium oxide.

5. The method for preparing silicon-containing compound fertilizer from fly ash aluminum residue according to claim 4, characterized in that: The weight ratio of the intermediate residue to the potassium-based activator, the magnesium-based activator, and the calcium-based activator is 1:(0.1-0.3):(0.2-0.6):(0.5-1.0).

6. The method for preparing silicon-containing compound fertilizer from fly ash aluminum residue according to claim 1 or 2, characterized in that: During the granulation process, a binder is added to the system. The amount of the binder is 0.01-0.05 g per gram of the silicon-containing compound fertilizer.

7. The method for preparing silicon-containing compound fertilizer from fly ash aluminum residue according to claim 6, characterized in that: The binder is selected from α-starch.

8. The method for preparing silicon-containing compound fertilizer from fly ash aluminum residue according to claim 1 or 2, characterized in that: Water is added to the system during the grinding process, and the weight ratio of water to the activated material during the grinding process is 1:1-3.

9. The method for preparing silicon-containing compound fertilizer from fly ash aluminum residue according to claim 1 or 2, characterized in that: The particle size of the sieved material is 1-4 mm.

10. The method for preparing silicon-containing compound fertilizer from fly ash aluminum residue according to claim 1 or 2, characterized in that: The drying temperature is 70-120° C. and the drying time is 30-150 min.

11. The method for preparing silicon-containing compound fertilizer from fly ash aluminum residue according to claim 1 or 2, characterized in that: The fly ash aluminum extraction residue includes 55-75 wt% of SiO2, 10-20 wt% of Al2O3, 7-12 wt% of residual carbon, 0.5-2.5 wt% of chloride and other inevitable impurities.

12. A silicon-containing compound fertilizer, characterized in that: The silicon-containing compound fertilizer is prepared by the method for preparing the silicon-containing compound fertilizer by extracting aluminum residue from fly ash according to any one of claims 1 to 11.

Images