Preparation method and application of tobermorite-rich high-ash coal slime-based silicon-calcium-potassium fertilizer

Abstract

The invention belongs to the technical field of comprehensive utilization of solid wastes, and particularly relates to a preparation method and application of a tobermorite-rich high-ash coal slime-based silicon-calcium-potassium fertilizer. Mixing the high-ash coal slime with a mineralizing agent, and then adding the mixture into an alkaline solution to obtain mixed slurry; and carrying out hydrothermal reaction and post-treatment on the mixed slurry to obtain a corresponding product. According to the preparation method disclosed by the invention, the high-ash coal slime-based silicon-calcium-potassium fertilizer with tobermorite and potassium-containing aluminosilicate can be obtained through the pretreatment of the raw materials and the cooperative control of the Ca / Si molar ratio, the reaction rotating speed, the alkali liquor concentration, the reaction temperature and the reaction time in the hydrothermal reaction; the high-ash coal slime-based silicon-calcium-potassium fertilizer contains effective silicon, calcium and potassium components; the soil conditioner can be applied to soil improvement and improvement of physical and chemical properties of soil, and can also be applied to heavy metal pollution adsorption / solidification.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of solid wastes, and specifically relates to a preparation method and application of a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite. Background Art

[0002] High-ash coal slime is a type of coal-based solid waste produced as coal washing technology continues to upgrade, mechanize and intelligentize. The resource utilization of this high-ash coal slime has become a new problem that needs to be urgently solved for the sustainable development of coal enterprises in recent years.

[0003] With the progress of industrialization and the emergence of modern agricultural intensive economic development model, global soil degradation is developing at an alarming rate, leading to problems such as soil nutrient deficiency, soil acidification and heavy metal pollution. Lead and cadmium are the most serious elements of heavy metal pollution in the world's soil, and unreasonable fertilizer application patterns have aggravated the problem of soil nutrient deficiency. In the face of non-point source heavy metal pollution and nutritional imbalance in the soil, adding silicon-containing soil conditioners or mineral fertilizers is an economical and effective feasible solution to achieve sustainable agricultural development.

[0004] Silicon, calcium, and potassium are all beneficial elements for plant growth. They enter the soil in the form of monoacids, ions, or complex ions to exert fertilizer effects. Silicon is the second most abundant element in the earth's crust. Effective silicon in the soil has been proven to not only increase crop yield and quality, but also effectively alleviate the biological and abiotic stresses of many plant species, improve soil structure and physical and chemical properties, resist heavy metal stress, and improve acidified soil. However, most of the silicon in the soil is inactive and cannot be directly absorbed and utilized by plants. For instant fertilizers, such as potash fertilizers, it is easy to cause soil nutrient loss. Therefore, the sustainable development of agriculture requires improving the utilization mode of chemical fertilizers and applying fertilizers with slow-release silicon, calcium, and potassium elements. At present, the mineral components contained in silicon mineral fertilizers or improvers are often dicalcium silicate, tricalcium silicate, sodium-containing zeolite, calcium-containing zeolite, etc.

[0005] Tobermorite is a naturally occurring hydrated calcium silicate, but it is relatively rare in nature and can be prepared by hydrothermal method in industry. As early as 1983, tobermorite was initially confirmed to have high selectivity for cesium, and then gradually confirmed to have strong adsorption capacity for heavy metals such as lead, cadmium, zinc, copper and nickel in aqueous solution. There are many studies on water treatment and cement hydration, such as Chinese patents CN112194148B and CN112194148B. Tobermorite not only has selective adsorption for heavy metals, but its crystal layered pore structure is also an important storage unit for calcium, potassium and other ions. In the preparation of soil conditioners or mineral fertilizers, Chinese patent CN108239536B discloses a method for preparing effective silicon soil conditioners using industrial solid waste, but this method only considers the maximization of the effective silicon content of the product, does not pay attention to the simultaneous preparation of slow-release potassium, and does not pay attention to the synthesis of tobermorite crystals and the application of the heavy metal solidification performance of the product. Summary of the invention

[0006] The present invention overcomes the shortcomings of the prior art and provides a preparation method and application of a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite; the present invention is achieved through the following technical solutions: A method for preparing a tobermorite-rich high-ash coal slime-based silicon-calcium-potassium fertilizer comprises the following steps: S1. Mix high-ash coal slime with a mineralizer, and then add the mixture into an alkaline solution to obtain a mixed slurry; the concentration of the alkaline solution is 0.4-1.0 mol / L; the Ca / Si molar ratio of the high-ash coal slime and the mineralizer is 0.5-1.1; S2. The mixed slurry is subjected to a hydrothermal reaction. After the reaction is completed, the mixed slurry is cooled, filtered, washed and dried to obtain a high-ash coal slime-based silicon-calcium-potassium fertilizer product rich in tobermorite; the temperature of the hydrothermal reaction is 170-230° C., the reaction time is 2-15 h, and the reaction speed is 0-170 rpm.

[0007] Preferably, the high-ash coal slime is pretreated by sulfuric acid acidification with a concentration of 1 to 4 mol / L. The high-ash coal slime treated with different concentrations of acid can prepare products with different silicon, calcium and potassium contents. When the sulfuric acid concentration is low, the effective silicon content of the prepared product can be appropriately increased. When the sulfuric acid concentration is high, the high-ash coal slime mainly participates in the reaction in the form of quartz phase, and the effective silicon content of the obtained product is reduced.

[0008] Preferably, the mineralizer is calcium oxide or calcium hydroxide powder, or a compound that can be converted into calcium oxide; for example, preferably one of slaked lime and quicklime.

[0009] Preferably, the alkaline solution is a KOH solution; the solid-liquid ratio of the obtained mixed slurry is 1:20.

[0010] More preferably, the concentration of the KOH solution is 1.0 mol / L.

[0011] The preferred KOH solution can completely dissolve the original silicon-containing components of the high-ash coal slime. When the concentration of the KOH solution is too low (less than 0.4 mol / L), the original silicon-containing components of the high-ash coal slime cannot be completely dissolved. When the KOH concentration is preferably 1.0 mol / L, the original silicon-containing quartz phase of the high-ash coal slime is completely dissolved, and the increase in effective silicon is not obvious. When the KOH concentration is too high (greater than 1.0 mol / L), the alkaline solution environment changes and other crystal structures are generated.

[0012] Preferably, the reaction speed of the hydrothermal reaction is 90 rpm, the temperature is 200-230° C., and the reaction time is 5-15 h.

[0013] The selection of the above-mentioned preferred reaction speed can completely dissolve the original silicon-containing components of the high-ash coal slime and is conducive to the formation of tobermorite. When the reaction speed is too low or too high, the content and proportion of effective silicon will be affected. When it is a static reaction or the speed is too low (less than 10rpm), the original silicon-containing components of the high-ash coal slime cannot be completely dissolved. When the speed is too high (greater than 170rpm), the formation of the tobermorite crystal phase will be reduced, and other silicate phases will be produced.

[0014] The selection of the above-mentioned preferred temperature can not only completely dissolve the original silicon-containing components of the high-ash coal slime, but also increase the effective silicon content. When the reaction temperature is too low (less than 170°C), the original silicon-containing components of the high-ash coal slime cannot be completely dissolved, affecting the effective silicon content. When the reaction temperature is too high (greater than 230°C), it will increase energy consumption, improve equipment performance requirements, increase costs, and generate other silicate crystal phases.

[0015] The selection of the above preferred time can not only completely dissolve the original silicon-containing components of the high-ash coal slime, but also increase the effective silicon content. When the reaction time is too low (less than 2h), the original silicon-containing components of the high-ash coal slime cannot be completely dissolved, affecting the effective silicon content. However, when the reaction time is too high (greater than 15h), the effective silicon content increases slowly, and the specific surface area of ​​the generated product begins to decrease, which is not conducive to the adsorption of heavy metals and also increases the cost.

[0016] Preferably, the Ca / Si molar ratio of the high-ash coal slime mixed with the mineralizer is 0.8.

[0017] The selection of the above preferred Ca / Si molar ratio can not only completely dissolve the original silicon-containing components of the high-ash coal slime, but also is more conducive to the crystallization of the tobermorite phase. A too low Ca / Si molar ratio (less than 0.5) cannot completely dissolve the original silicon-containing components of the high-ash coal slime, affecting the effective silicon content. A too high Ca / Si molar ratio (greater than 1.1) increases the effective silicon content only slightly and weakens the crystallinity of the tobermorite phase.

[0018] Preferably, the cooling is water cooling or natural cooling.

[0019] The invention discloses an application of a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite in soil improvement and heavy metal pollution adsorption / solidification. The high-ash coal slime-based silicon-calcium-potassium fertilizer is prepared by the preparation method of the high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite.

[0020] The beneficial effects of the present invention compared with the prior art are as follows: 1. The present invention can obtain a high-ash coal slime-based silicon-calcium-potassium fertilizer having tobermorite and potassium-aluminum silicate by coordinated control of the Ca / Si molar ratio, reaction speed, alkali solution concentration, reaction temperature and reaction time in the pretreatment of raw materials and the hydrothermal reaction; the high-ash coal slime-based silicon-calcium-potassium fertilizer has effective silicon, calcium and potassium components; the high-ash coal slime-based silicon-calcium-potassium fertilizer prepared by the present invention is rich in tobermorite, and the formed tobermorite has a silicon (aluminum) oxygen tetrahedral skeleton structure, which is not only an important slow-release reservoir of potassium and calcium ions, but also can show good heavy metal solidification performance.

[0021] 2. The method of the present invention synthesizes tobermorite and potassium aluminum silicate by activating and recombining the silicon component in high-ash coal slime, which can be used for soil improvement to improve the physical and chemical properties of the soil, and can also be used for heavy metal pollution adsorption / solidification. The process of the present invention is simple, low in energy consumption, green and low-carbon, effectively reduces the production cost, and can achieve the comprehensive utilization of high-ash coal slime solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a scanning electron microscope image of the product prepared in Example 1 of the present invention; Figure 2 The nitrogen adsorption-desorption curves of the product prepared in Example 1 of the present invention and the raw material high-ash coal slime; Figure 3 This is a scanning electron microscope-energy spectrum analysis diagram of the product prepared in Example 2 of the present invention; Figure 4 XRD patterns of the product prepared in Example 2 of the present invention before and after leaching in hydrochloric acid; Figure 5 This is a graph showing the release pattern of effective silicon, calcium and potassium nutrients of the product prepared in Example 3 of the present invention; Figure 6 This is a scanning electron microscope-energy spectrum analysis diagram of the product prepared in Example 4 of the present invention; Figure 7 This is a scanning electron microscope-energy spectrum analysis diagram of the residue after lead adsorption by the product prepared in Example 4 of the present invention; Figure 8This is a scanning electron microscope-energy spectrum analysis diagram of the residue after cadmium adsorption by the product prepared in Example 4 of the present invention; Fig. 9 The XRD pattern of the product prepared in Example 5 of the present invention and the residue after the product adsorbs lead and cadmium; Fig.10 This is a scanning electron microscope image of the product prepared in Example 8 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail in conjunction with the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The technical solutions of the present invention are described in detail below in conjunction with the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0024] The following Examples 1-12 and Comparative Examples 1-4 all use the same high-ash coal slime as a silicon source, and the silicon-containing components in the high-ash coal slime are quartz and kaolinite. The comparative example data are only for more clearly illustrating the content of the present invention, and the application scope of the present invention should not be limited to the experimental data in the examples.

[0025] Example 1 This embodiment provides a method for preparing a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite, which specifically comprises the following steps: The high-ash coal slime and lime were simply mixed at a Ca / Si molar ratio of 0.8 and added to a KOH solution with a solid-liquid mass ratio of 1:20 to obtain a mixed slurry with a KOH solution concentration of 1 mol / L; the mixed slurry was placed in a reactor for hydrothermal reaction, the hydrothermal reaction time was set to 5h, the reaction speed was 90rpm, and the reaction temperature was 230°C. After the reaction was completed, the reactor was opened and the material was discharged after natural cooling to room temperature; the product obtained by the reaction was then vacuum washed and filtered, and the washed solid phase was dried to obtain a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite.

[0026] The effective silicon, calcium and potassium contents of the product in this embodiment are 23.18, 22.93 and 3.01 wt % respectively. The crystalline phase of the product includes tobermorite, hydrocalcium zeolite and potassium-containing aluminum silicate. The characteristic diffraction peak of tobermorite is obvious; the average pore diameter is 18 nm, and the specific surface area is 44.46 m 2 / g, the specific surface area of ​​high ash coal slime is higher than that of raw material (10.24m 2 / g) increased by 3.33 times (see Figure 1 and Figure 2 ).

[0027] Example 2 This embodiment proposes a method for preparing a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite. Compared with Example 1, the difference is that the hydrothermal reaction time is 15 hours, the cooling method is water cooling, and the rest is the same as Example 1.

[0028] The effective silicon, calcium and potassium contents of the product in this embodiment are 30.24, 19.79 and 7.25wt% respectively. The crystalline phase of the product mainly includes tobermorite and potassium-containing aluminum silicate. The characteristic diffraction peak of tobermorite is obvious; the particles are fibrous agglomerates; the leaching rate of effective elements in aqueous solution is significantly lower than that of acid solution. After leaching in ultrapure water for 0.5h, the type of crystals does not change, but the peak of some crystals weakens. After the product is placed in 0.5mol / L HCl for 0.5h and 23h, all the original phases in the product are dissolved and a new white mica crystal phase is generated. It can be seen that the nutrients in the product have slow release properties (see Figure 3 and Figure 4 ) Figure 4 The curve corresponding to Example 2 is the XRD spectrum of the prepared high-ash coal slime-based silicon-calcium-potassium fertilizer, HCl-0.5h is the XRD spectrum of the high-ash coal slime-based silicon-calcium-potassium fertilizer after leaching in hydrochloric acid for half an hour, HCl-23h is the XRD spectrum of the high-ash coal slime-based silicon-calcium-potassium fertilizer after leaching in hydrochloric acid for 23 hours; H2O-0.5h is the XRD spectrum of the high-ash coal slime-based silicon-calcium-potassium fertilizer after leaching in water for half an hour.

[0029] Example 3 The product in this example is the product in Example 1. This example provides the release law of effective nutrients of the product in a simulated plant root environment (pH 5.2). The release of effective silicon dioxide conforms to the Elovich equation, the release of effective calcium oxide conforms to the Elovich equation, and the release of effective potassium oxide conforms to the first-order kinetic equation (see Figure 5 ).

[0030] Example 4 This embodiment proposes a method for preparing a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite. Compared with Example 1, the difference is that the temperature of the hydrothermal reaction is reduced to 200° C., and the rest is the same as Example 1.

[0031] The effective silicon, calcium and potassium contents of the product in this embodiment are 20.76, 23.64 and 2.43 wt % respectively, and the characteristic diffraction peak of tobermorite is obvious.

[0032] In this embodiment, the application of the product in heavy metal adsorption is provided. The test process is as follows: 500 mg / L and 200 mg / L solutions are prepared with the acetate of the corresponding lead / cadmium heavy metal to be tested, respectively, and the pH value of the solution is adjusted to 5.2 to obtain a heavy metal ion solution. 50 mg of the product is put into 40 mL of the heavy metal ion solution, and the product is taken out after oscillation at 180 rpm on a constant temperature oscillator (temperature controlled at (25±0.2)°C) for 48 hours. The adsorption amount of the product for single metal ions of lead and cadmium is measured to be 186 mg / g and 65 mg / g, respectively (see Figures 6 to 8 ).

[0033] Example 5 The product in this example is the product in Example 1. The heavy metal adsorption experimental method in Example 4 is used. The adsorption amounts of single metal ions of lead and cadmium by the product in Example 1 are 138 mg / g and 59 mg / g respectively. The newly generated lead silicate and cadmium silicate precipitates in the adsorption residue are important results of the activation of silicon in the product and the presence of tobermorite phase (see Fig. 9 ).

[0034] Example 6 The product in this embodiment is the product in Example 2. In this embodiment, the application of the product in fixing lead in heavy metal contaminated soil is provided. The test process is as follows: the product of Example 2 is added to the lead contaminated soil at a mass percentage of 0.4%, and cultured in a light-proof room for 90 days. Deionized water is added once every 3 to 4 days on average during the culture period. The weighing method is used to maintain the on-site water holding capacity at 70%. The content of lead in different forms in the soil is measured after 90 days. Compared with the lead-contaminated soil to which the product of Example 2 is not added, the exchangeable lead decreases by 36%, the carbonate-bound lead decreases by 6%, and the residual lead increases by 6.29%.

[0035] Example 7 This embodiment proposes a method for preparing a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite. Compared with Example 2, the difference is that the hydrothermal reaction time is 5 hours, and the rest is the same as Example 2.

[0036] The effective silicon, calcium and potassium contents of the product in this embodiment are 25.12, 21.78 and 5.03 wt % respectively. The crystalline phase of the product mainly includes tobermorite and potassium-containing aluminum silicate, and the characteristic diffraction peak of tobermorite is obvious.

[0037] Example 8 This embodiment proposes a method for preparing a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite. Compared with Example 2, the difference is that before the hydrothermal reaction, the high-ash coal slime is pretreated with 1 mol / L sulfuric acid, that is, the high-ash coal slime is pickled with sulfuric acid, and the rest is the same as Example 2.

[0038] The effective silicon, calcium and potassium contents of the product in this embodiment are 31.24, 20.95 and 6.68 wt % respectively. The crystalline phase of the product mainly includes tobermorite and potassium-containing aluminum silicate. The characteristic diffraction peak of tobermorite is obvious, and the particle morphology between tobermorite and potassium-containing aluminum silicate is more distinct (see Fig.10 ).

[0039] Example 9 This embodiment provides a method for preparing a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite. Compared with Example 2, the difference is that calcium hydroxide is used instead of lime, and the rest is the same as Example 2.

[0040] The effective silicon, calcium and potassium contents of the product in this embodiment are 28.81, 19.86 and 7.15 wt % respectively, and the characteristic diffraction peak of tobermorite is obvious in the crystal phase of the product.

[0041] Example 10 This embodiment provides a method for preparing a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite. Compared with Example 2, the difference is that the KOH concentration is set to 0.4 mol / L, and the rest is the same as Example 2.

[0042] Embodiment 11 This embodiment provides a method for preparing a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite. Compared with Example 2, the difference is that the KOH concentration is set to 0.8 mol / L, and the rest is the same as Example 2.

[0043] Example 12 This embodiment provides a method for preparing a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite. Compared with Example 2, the difference is that the hydrothermal reaction time is 2 hours, the rotation speed is 10 rpm, and the temperature is 170°C; the rest is the same as Example 2.

[0044] Comparative Example 1 This comparative example provides a method for preparing high-ash coal slime-based silicon-calcium-potassium fertilizer. Compared with Example 2, the difference is that the hydrothermal reaction time is 1 hour, the KOH concentration is set to 0.1 mol / L, and the rest is the same as Example 2.

[0045] The effective silicon, calcium and potassium contents of the product in this comparative example are 8.18, 18.37 and 0.25 wt % respectively, and there is no characteristic diffraction peak of tobermorite in the crystal phase of the product.

[0046] Comparative Example 2 This comparative example provides a method for preparing high-ash coal slime-based silicon-calcium-potassium fertilizer. Compared with Example 2, the difference is that the hydrothermal reaction temperature is 170°C, and the rest is the same as Example 2.

[0047] The effective silicon, calcium and potassium contents of the product in this comparative example are 14.55, 20.96 and 4.03 wt % respectively, and there is almost no characteristic diffraction peak of tobermorite in the crystal phase of the product.

[0048] Comparative Example 3 This comparative example provides a method for preparing high-ash coal slime-based silicon-calcium-potassium fertilizer. Compared with Example 2, the difference is that the hydrothermal reaction time is 5 hours, the Ca / Si molar ratio is 1.1, and the rest is the same as Example 2.

[0049] The effective silicon, calcium and potassium contents of the product in this comparative example are 25.54, 22.81 and 6.76 wt % respectively. The characteristic diffraction peak of tobermorite in the crystal phase of the product is obvious, but the peak intensity is weaker than that of the tobermorite peak of the product in Example 5.

[0050] Comparative Example 4 This comparative example provides a method for preparing high-ash coal slime-based silicon-calcium-potassium fertilizer. Compared with Example 2, the difference is that before the hydrothermal reaction, the high-ash coal slime is pretreated by acidification with 4 mol / L sulfuric acid, and the rest is the same as Example 2.

[0051] The effective silicon, calcium and potassium contents of the product in this comparative example are 17.35, 26.22 and 7.29 wt % respectively. The crystalline phase of the product mainly includes tobermorite and potassium-containing aluminum silicate, and the characteristic diffraction peak of tobermorite is obvious.

[0052] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be determined that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the present invention, which should be regarded as belonging to the present invention and the scope of patent protection determined by the submitted claims.

Claims

1. A method for preparing a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite, characterized in that: The following steps are involved: S1, mixing high-ash coal slime with a mineralizer, and then adding the mixture into an alkaline solution to obtain a mixed slurry; The concentration of the alkaline solution is 0.4-1.0 mol / L; the Ca / Si molar ratio of the mixture of high-ash coal slime and mineralizer is 0.5-1.1; S2. The mixed slurry is subjected to a hydrothermal reaction. After the reaction is completed, the mixed slurry is cooled, filtered, washed and dried to obtain a high-ash coal slime-based silicon-calcium-potassium fertilizer product rich in tobermorite; the temperature of the hydrothermal reaction is 170-230° C., the reaction time is 2-15 h, and the reaction speed is 10-170 rpm.

2. The method for preparing a tobermorite-rich high-ash coal slime-based silicon-calcium-potassium fertilizer according to claim 1, characterized in that: High-ash coal slime is coal slime that has been pretreated with sulfuric acid at a concentration of 1~4 mol / L.

3. The method for preparing a tobermorite-rich high-ash coal slime-based silicon-calcium-potassium fertilizer according to claim 1, characterized in that: The mineralizer is calcium oxide or calcium hydroxide powder.

4. The method for preparing a tobermorite-rich high-ash coal slime-based silicon-calcium-potassium fertilizer according to claim 1, characterized in that: The alkaline solution is a KOH solution; the solid-liquid ratio of the obtained mixed slurry is 1:

20.

5. The method for preparing a tobermorite-rich high-ash coal slime-based silicon-calcium-potassium fertilizer according to claim 4, characterized in that: The concentration of the KOH solution is 1.0 mol / L.

6. The method for preparing a tobermorite-rich high-ash coal slime-based silicon-calcium-potassium fertilizer according to claim 1, characterized in that: The reaction speed of the hydrothermal reaction is 90 rpm, the temperature is 200~230°C, and the reaction time is 5~15h.

7. The method for preparing a tobermorite-rich high-ash coal slime-based silicon-calcium-potassium fertilizer according to claim 1, characterized in that: The Ca / Si molar ratio of high-ash coal slime mixed with mineralizer is 0.

8.

8. The method for preparing a tobermorite-rich high-ash coal slime-based silicon-calcium-potassium fertilizer according to claim 1, characterized in that: The cooling is water cooling or natural cooling.

9. Application of a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite in soil improvement and heavy metal pollution adsorption / solidification, characterized in that: The high-ash coal slime-based silicon-calcium-potassium fertilizer is prepared by the preparation method of a high-ash coal slime-based silicon-calcium-potassium fertilizer rich in tobermorite as described in any one of claims 1 to 8.

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