Silicon fertilizer preparation method for improving effective silicon conversion rate of coal gangue and reducing energy consumption

Abstract

The invention belongs to the technical field of preparation of a silicon fertilizer from coal gangue, and particularly relates to a silicon fertilizer preparation method for improving the effective silicon conversion rate of coal gangue and reducing energy consumption. The invention aims to solve the problems of low silicon resource utilization rate and high energy consumption in the prior art. The preparation method comprises the following steps: (1) crushing coal gangue, sieving and drying for later use; (2) adding a specific auxiliary agent and coal gangue according to a certain proportion, and fully mixing; (3) roasting the mixture at a certain temperature for a certain time; and (4) cooling the roasted product to obtain the silicon fertilizer. The silicon dioxide in the coal gangue can be effectively converted into silicate which can be conveniently absorbed and utilized by plants, the yield of the silicon fertilizer is increased, the environmental problem caused by accumulation of the coal gangue can be solved, the silicon fertilizer can also be used as a soil improvement material, good economic benefits and social benefits are achieved, and a solid foundation is laid for wide utilization of the coal gangue. Compared with a traditional method, the method has obvious economic and environmental benefits.

Description

Technical Field

[0001] The invention relates to the technical field of preparing silicon fertilizer by utilizing coal gangue, and in particular to a method for preparing silicon fertilizer which can improve the effective silicon conversion rate of coal gangue and reduce energy consumption. Background Art

[0002] Coal gangue (CG) is a byproduct of coal mining and washing. It is produced in huge quantities every year and has traditionally been treated as waste. Coal gangue is mainly composed of silicon dioxide and aluminum oxide, containing very little silicate minerals, carbon and a small amount of other minerals, among which the content of silicon dioxide is relatively high. However, due to its inherent structural characteristics and chemical stability, it is difficult to directly use it to provide silicon nutrition for crops.

[0003] Silicon is one of the essential nutrients for plant growth, and plays an important role in improving crop resistance (such as drought resistance and disease resistance) and enhancing mechanical strength. However, in nature, although silicon is abundant, most of it exists in an insoluble form, making it difficult for plants to absorb directly. Therefore, developing a silicon fertilizer that is easy for plants to absorb has become an important direction of agricultural research.Silicon fertilizers on the market are mainly produced by chemical synthesis. These methods are not only costly, but also may impose a certain burden on the environment during the production process. Among them, some methods add caustic soda solution to strengthen the calcification leaching reaction. After the reaction is completed, the liquid and solid are separated, and the filter cake is the silicon fertilizer. However, the alkalinity in the calcification leaching reaction strengthened by the addition of caustic soda solution is relatively high, and the equipment requirements are high. The subsequent solid-liquid separation may cause the loss of effective silicon; some methods use coal gangue as raw material, potassium feldspar and limestone as auxiliary materials, and add alkali metal salts and alkali metal oxides as alkaline compounds. According to a certain ratio, high-temperature activation and water mist quenching, drying, and finished product crushing and granulation are carried out to prepare silicon potassium fertilizer. The steps are relatively cumbersome and the thermal activation temperature is relatively high. High, resulting in high energy consumption and high performance requirements for equipment; some methods use coal gangue as raw material, limestone as auxiliary material and alkali metal salt as auxiliary material, and prepare silicon fertilizer by high-temperature activation and water mist quenching, drying and finished product crushing according to a certain ratio. The ratio of coal gangue to lime is as high as 2:1, and the thermal activation temperature is relatively high, resulting in high energy consumption and high performance requirements for equipment; some methods mix high-silicon iron tailings powder with calcium-containing activator and alkaline activator solution, ultrasonically treat to obtain a mixture, hydrothermally react the mixture, and dry it after the hydrothermal reaction to obtain silicon fertilizer. This method requires ultrasonic treatment and hydrothermal reaction, and the energy consumption is relatively high; some methods activate attapulgite powder of a certain purity and particle size , modification treatment to obtain nano-attapulgite, which is mixed with biochar, potassium humate, microbial agents, etc. in proportion to obtain nano silicon fertilizer. This method has high requirements on raw materials and requires activation and modification of attapulgite powder. The method is relatively cumbersome and the modification process is prone to secondary pollution; some methods mix coal gangue and organic solid waste, and successively perform pyrolysis treatment, staged calcination and stabilization, quenching and crushing to obtain the silicon fertilizer. This method requires that the lime content of coal gangue Ad ≥ 85% and the organic solid content K2O> 1.5%, Na2O ≤ 1.0%, and its universality is relatively low; some methods obtain primary micro-nano materials of iron tailings by mechanical grinding, and then further reduce the particle size by chemical dissolution technology diameter to obtain micro-nano silicon material, and reasonably adjust the distribution ratio of the micro-nano particle size in the material to prepare a slow-release silicon improved material. The energy consumption of the ball milling step for preparing primary micro-nano materials in this method is too high, and the subsequent use of chemical dissolution technology may also cause secondary pollution; some methods are to place diatomaceous earth in an alkaline solution to form a mixed solution, add hydrogen peroxide to the mixed solution, heat and stir it, perform high-pressure hydrothermal heating, cool it, and perform solid-liquid separation, add acid to the separated solution to neutralize it and adjust the pH to 7-9, and after standing, obtain silicon fertilizer by different shear speeds. This method is a wet method for preparing silicon fertilizer, which has complicated steps and requires the addition of different acid and alkali solutions and hydrogen peroxide, etc. There are many chemical products, which may cause secondary pollution to the environment and have high costs.

[0004] Therefore, developing a low-cost, environmentally friendly silicon fertilizer preparation technology has important practical significance and broad market prospects. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing silicon fertilizer which can improve the effective silicon conversion rate of coal gangue and reduce energy consumption, and realize efficient recovery and conversion of silicon resources through the mixed roasting technology of coal gangue and additives, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption, the steps comprising:

[0008] The coal gangue and the additive are mixed and roasted to obtain the silicon fertilizer;

[0009] The auxiliary agent includes at least one of carbonates containing potassium, calcium, magnesium, sodium and lithium.

[0010] Furthermore, the coal gangue and the additive are sieved through a 1-200 mesh sieve before being mixed.

[0011] Furthermore, the mass ratio of the coal gangue to the additive is 20:1 to 1:1.

[0012] Furthermore, the calcination treatment is performed at a temperature of 200 to 1500° C. and a time of 0 to 12 hours, and is not 0.

[0013] Compared with the previous technology, the present invention has significant innovation and beneficial effects in the preparation of silicon fertilizer using coal gangue. First, compared with the traditional roasting method, the present invention can significantly reduce the energy consumption and cost of the silicon fertilizer production process. In the traditional method, high temperature conditions and long-term continuous heating are usually required, which consumes a lot of energy and has a long cycle. The present invention achieves the improvement of the conversion rate of effective silicon at a relatively low temperature by rationally proportioning coal gangue and additives and optimizing the roasting process parameters, which not only greatly saves energy consumption and reduces production costs, but also improves production efficiency and shortens the production cycle, thereby creating greater economic benefits for the enterprise. Furthermore, the preparation method of the present invention also has significant effects on the effective utilization of resources and environmental protection. The use of discarded coal gangue resources to prepare silicon fertilizer not only realizes the reuse of resources, but also effectively reduces the pollution of waste to the environment, realizes the resource utilization of coal gangue, and makes positive contributions to environmental protection and sustainable development. The method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption provided by the present invention has many significant advantages over previous technologies, such as reducing energy consumption, improving product quality, promoting resource recycling and protecting the environment, and is expected to have a broad and far-reaching impact in the fields of agricultural production and environmental protection.

[0014] There are a lot of silicon dioxide crystals in coal gangue. Silica is a covalent bond structure formed by one silicon atom and two oxygen atoms. Each silicon atom is connected to four oxygen atoms through covalent bonds to form a three-dimensional network structure. These silicon-oxygen bonds are very strong and have high bond energy. 2- When close to silicon dioxide, due to its high electronegativity and negative charge, it will exert a strong electrostatic force on the silicon-oxygen bond in the silicon dioxide structure. This electrostatic force will polarize the silicon-oxygen bond, resulting in an increase in bond length, a decrease in bond energy, and ultimately the breaking of the bond. Under high temperature conditions, the energy and electronegativity effect provided by oxygen ions break the silicon-oxygen bond in silicon dioxide. 2- Approaching a silicon-oxygen bond in silicon dioxide, the oxygen ion forms a strong electrostatic attraction with the oxygen atom in the silicon-oxygen bond, pulling the oxygen atom away from the silicon atom, polarizing the silicon-oxygen bond, increasing the bond length, and reducing the bond energy, which eventually leads to the breaking of the silicon-oxygen bond, generating a free silicon atom and an oxygen ion. Once the silicon-oxygen bond is broken, the free silicon atom and oxygen ion will recombine under high temperature conditions to form silicate. Since the order of ion radius is: Na + <Ca 2+ <K + , Na + , K + , Ca 2+ The coordination numbers are 6, 6, and 8, respectively, which leads to a high charge density of the sodium ion group carried by the oxygen ion, a more compact structure, and a small steric hindrance, making it easier to attack the Si-O bond, causing the Si-O bond to polarize, break, and then reorganize. Therefore, the formation of oxygen ions in the process of preparing silicon fertilizer and the ability to attack the Si-O bond are key factors in the preparation of silicon fertilizer. At relatively low temperatures, sodium carbonate is more likely to decompose into sodium oxide to form oxygen ions, and the sodium ion group carried by oxygen ions is more likely to attack the Si-O bond, so sodium carbonate is more advantageous as an auxiliary agent. This reaction mechanism explains the important role of sodium carbonate in the preparation of silicon fertilizer from coal gangue.

[0015] The second technical solution of the present invention is to provide a silicon fertilizer prepared by the above preparation method.

[0016] The third technical solution of the present invention is to provide a method for improving the effective silicon conversion rate of coal gangue when preparing silicon fertilizer from coal gangue, the steps comprising:

[0017] The gangue and the additive are mixed and roasted;

[0018] The auxiliary agent includes at least one of carbonates containing potassium, calcium, magnesium, sodium and lithium.

[0019] Furthermore, the coal gangue and the additive are sieved through a 1-200 mesh sieve before being mixed.

[0020] Furthermore, the mass ratio of the coal gangue to the additive is 20:1 to 1:1.

[0021] Furthermore, the calcination treatment is carried out at a temperature of 200 to 1500° C. and for a time of 0 to 12 hours.

[0022] The fourth technical solution of the present invention is to provide an application of the above method for increasing the effective silicon content of silicon fertilizer when preparing silicon fertilizer.

[0023] The present invention can effectively convert silicon dioxide in coal gangue into silicate which is easy for plants to absorb and utilize, can help solve the environmental problems of coal gangue, and can also provide efficient soil improvement materials for agricultural production. It has good economic and social benefits and lays a solid foundation for the extensive utilization of coal gangue.

[0024] The present invention discloses the following technical effects:

[0025] The present invention utilizes coal gangue, which is traditionally regarded as waste, to prepare silicon fertilizer, thereby reducing the production cost of silicon fertilizer, and by simplifying the process flow, reducing energy consumption and environmental pollution. It not only improves the utilization rate of silicon resources in coal gangue, but also has obvious environmental and social benefits. By optimizing the roasting process and raw material ratio, production efficiency is improved, and the development of industrialized production of silicon fertilizer is promoted, sustainable resource utilization and environmental protection are promoted, providing a new solution for agricultural production.

[0026] The present invention solves the problems of long temperature and time, high energy consumption, etc. in the traditional roasting process by adding different additives. The present invention can significantly reduce the energy consumption in the preparation process of silicon fertilizer. In the traditional roasting process, high temperature conditions and long-term continuous heating are usually required to realize the conversion of materials, resulting in large energy consumption and a long production cycle. However, by adopting the technical scheme of the present invention, by adding appropriate alkali compounds and adjusting roasting parameters, the effective conversion of coal gangue can be achieved at a relatively low temperature, while shortening the roasting time, preparing qualified silicon fertilizer, and greatly saving energy and production costs. In addition, the present invention also has significant economic and social benefits. By reducing the roasting temperature and time, energy consumption and production costs are reduced, production efficiency is improved, and thus the production cost of the product is reduced. At the same time, the optimized roasting product has a wider range of applications and better performance, can meet the needs of different industries, and create a greater market competitive advantage for enterprises. At the social level, the present invention promotes the effective use of resources and environmental protection, helps to promote the implementation of the sustainable development strategy, and makes a positive contribution to social and economic development. In general, the scheme of the present invention transforms the silicon dioxide in the coal gangue into silicon fertilizer with a certain price through innovative processing means, laying a foundation for the resource utilization of coal gangue. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A comparison chart of the effective silicon content in the silicon fertilizer and coal gangue prepared in Example 1 and Examples 16-17;

[0029] Figure 2 This is a comparison chart of the effective silicon content of the silicon fertilizer when the auxiliary agent is calcium carbonate in Example 18;

[0030] Figure 3 This is a comparison chart of the effective silicon content of silicon fertilizer when the auxiliary agent is potassium carbonate in Example 19;

[0031] Figure 4 This is a comparison chart of the effective silicon content of the silicon fertilizer when the auxiliary agent is sodium carbonate in Example 20;

[0032] Figure 5 The XRD spectra of coal gangue from different regions before and after roasting, where (a) is before roasting and (b) is after roasting;

[0033] Figure 6 The simulation results of the roasting reaction of coal gangue with different additives added are given. DETAILED DESCRIPTION

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0036] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0037] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0038] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0039] The raw materials and reagents used in the specific implementation of the present invention are all commercially available products, among which the coal gangue is provided by Nanchang Menglan Biotechnology Co., Ltd.

[0040] Example 1

[0041] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0042] S1. Prepare coal gangue and sodium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and sodium carbonate through a 100-mesh sieve;

[0043] S2. Mix the pretreated coal gangue and sodium carbonate in a mass ratio of 8:2, then heat up at a rate of 8°C / min, and keep the temperature at 700°C for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0044] Example 2

[0045] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0046] S1. Prepare coal gangue and sodium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and sodium carbonate through an 80-mesh sieve;

[0047] S2. Mix the pretreated coal gangue and sodium carbonate in a mass ratio of 6:4, then heat up at a rate of 8°C / min, and keep the temperature at 800°C for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0048] Example 3

[0049] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0050] S1. Prepare coal gangue and magnesium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and magnesium carbonate through a 100-mesh sieve;

[0051] S2. Mix the pretreated coal gangue and magnesium carbonate in a mass ratio of 7:3, then heat up at a rate of 8°C / min, and keep the temperature at 700°C for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0052] Example 4

[0053] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0054] S1. Prepare coal gangue and sodium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and sodium carbonate through a 100-mesh sieve;

[0055] S2. Mix the pretreated coal gangue and sodium carbonate in a mass ratio of 7:3, then heat up at a rate of 8°C / min, and keep the temperature at 800°C for 2 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0056] Example 5

[0057] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0058] S1. Prepare coal gangue and calcium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and calcium carbonate through a 100-mesh sieve;

[0059] S2. The pretreated coal gangue and calcium carbonate are mixed in a mass ratio of 8:2, and then the temperature is increased at a rate of 8°C / min. After reaching a holding temperature of 800°C, the mixture is kept warm for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0060] Example 6

[0061] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0062] S1. Prepare coal gangue and potassium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and potassium carbonate through a 100-mesh sieve;

[0063] S2. The pretreated coal gangue and potassium carbonate are mixed in a mass ratio of 9:1, and then the temperature is increased at a rate of 8°C / min. After reaching a holding temperature of 800°C, the mixture is kept warm for 1 hour to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0064] Example 7

[0065] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0066] S1. Prepare coal gangue and sodium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and sodium carbonate through a 100-mesh sieve;

[0067] S2. Mix the pretreated coal gangue and sodium carbonate in a mass ratio of 8:2, then heat up at a rate of 8°C / min, and keep the temperature at 600°C for 2 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0068] Example 8

[0069] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0070] S1. Prepare coal gangue and calcium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and calcium carbonate through a 120-mesh sieve;

[0071] S2. The pretreated coal gangue and calcium carbonate are mixed in a mass ratio of 6:4, and then the temperature is increased at a rate of 8°C / min. After reaching a holding temperature of 700°C, the mixture is kept warm for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0072] Example 9

[0073] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0074] S1. Prepare coal gangue and calcium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and calcium carbonate through a 100-mesh sieve;

[0075] S2. The pretreated coal gangue and calcium carbonate are mixed in a mass ratio of 8:2, and then the temperature is increased at a rate of 8°C / min. After reaching a holding temperature of 1000°C, the mixture is kept warm for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0076] Example 10

[0077] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0078] S1. Prepare coal gangue and magnesium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and magnesium carbonate through a 120-mesh sieve;

[0079] S2. Mix the pretreated coal gangue and magnesium carbonate in a mass ratio of 7:3, then heat up at a rate of 8°C / min, and keep the temperature at 700°C for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0080] Embodiment 11

[0081] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0082] S1. Prepare coal gangue and potassium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and potassium carbonate through an 80-mesh sieve;

[0083] S2. The pretreated coal gangue and potassium carbonate are mixed in a mass ratio of 8:2, and then the temperature is increased at a rate of 8°C / min. After reaching a holding temperature of 900°C, the mixture is kept warm for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0084] Example 12

[0085] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0086] S1. Prepare coal gangue and potassium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and potassium carbonate through an 80-mesh sieve;

[0087] S2. The pretreated coal gangue and potassium carbonate are mixed in a mass ratio of 6:4, and then the temperature is increased at a rate of 8°C / min. After reaching a holding temperature of 700°C, the mixture is kept warm for 0.5h to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0088] Embodiment 13

[0089] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0090] S1. Prepare coal gangue and magnesium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and magnesium carbonate through a 200-mesh sieve;

[0091] S2. The pretreated coal gangue and magnesium carbonate are mixed in a mass ratio of 6:4, and then the temperature is increased at a rate of 8°C / min. After reaching a holding temperature of 900°C, the mixture is kept warm for 1 hour to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0092] Embodiment 14

[0093] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0094] S1. Prepare coal gangue and sodium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and sodium carbonate through a 100-mesh sieve;

[0095] S2. Mix the pretreated coal gangue and sodium carbonate in a mass ratio of 6:4, then heat up at a rate of 8°C / min, and keep the temperature at 1000°C for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0096] Embodiment 15

[0097] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0098] S1. Prepare coal gangue and magnesium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and magnesium carbonate through a 100-mesh sieve;

[0099] S2. The pretreated coal gangue and magnesium carbonate are mixed in a mass ratio of 7:3, and then the temperature is increased at a rate of 8°C / min. After reaching a holding temperature of 600°C, the mixture is kept warm for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0100] Comparative Example 1

[0101] The method for preparing silicon fertilizer from coal gangue comprises the following steps:

[0102] The coal gangue is ball-milled and passed through a 250-mesh sieve, and limestone and alkali metal oxides (CaO, MgO, K2O, mass ratio 20:15:2) are added to prepare square materials to obtain pretreated coal gangue, which is then calcined at 1300°C for 4h, quenched, and then dried to obtain silicon fertilizer.

[0103] Comparative Example 2

[0104] The method for preparing silicon fertilizer from coal gangue comprises the following steps:

[0105] Prepare coal gangue and organic solid waste materials (K2O>1.5%, Na2O≤1.0%), crush them, mix them in a mass ratio of 60:40 to obtain pretreated coal gangue, and then carry out two-stage calcination, wherein the first stage is calcined at 725°C for 25min in air, and the second stage is calcined at 890°C for 90min in air-tight condition, and then quenched and dried to obtain silicon fertilizer.

[0106] The silicon fertilizers prepared in Examples 1 to 15 and Comparative Examples 1 to 2 were tested for effective silicon content using molybdenum blue spectrophotometry. The results are shown in Table 1.

[0107] Table 1

[0108]

[0109]

[0110] It can be seen from the data in Table 1 that under the same conditions, the effective silicon content of the silicon fertilizer prepared by the auxiliary agent sodium carbonate is higher than that of other auxiliary agents, the temperature required to obtain qualified silicon fertilizer is lower and the amount of coal gangue consumed is larger, which has obvious advantages. Comparative Example 1 uses coal gangue as raw material, limestone as auxiliary material and alkali metal salt as auxiliary material, and prepares silicon fertilizer by high-temperature activation and water mist quenching, drying and finished product crushing according to a certain ratio. The ratio of coal gangue to lime is as high as 2:1, and the thermal activation temperature is relatively high, resulting in high energy consumption and high performance requirements for equipment. Comparative Example 2 mixes coal gangue and organic solid waste, and successively performs pyrolysis treatment, staged calcination and stabilization, quenching and crushing to obtain the silicon fertilizer. This method requires coal gangue lime content Ad≥85% and organic solid waste K2O>1.5%, Na2O≤1.0%, and moisture≤30%, and its universality is relatively low.

[0111] Example 16

[0112] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0113] S1. Prepare coal gangue and potassium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and potassium carbonate through a 100-mesh sieve;

[0114] S2. The pretreated coal gangue and potassium carbonate are mixed in a mass ratio of 6:4, and then the temperature is increased at a rate of 8°C / min. After reaching a holding temperature of 800°C, the mixture is kept warm for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0115] Embodiment 17

[0116] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0117] S1. Prepare coal gangue and calcium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and calcium carbonate through a 100-mesh sieve;

[0118] S2. The pretreated coal gangue and calcium carbonate are mixed in a mass ratio of 6:4, and then the temperature is increased at a rate of 8°C / min. After reaching a holding temperature of 1500°C, the mixture is kept warm for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0119] Figure 1The comparison chart of the effective silicon content in the silicon fertilizer and coal gangue prepared in Example 1 and Examples 16-17 is shown in FIG. Figure 1 It can be seen that the addition of sodium carbonate and potassium carbonate can significantly increase the effective silicon content at relatively low temperatures, while the effective silicon content of calcium carbonate can only be increased at relatively high temperatures. Therefore, under the same conditions, the order of the strength of the additives that can improve the effective silicon conversion efficiency of coal gangue is: Na2CO3>K2CO3>CaCO3.

[0120] The cost of preparing silicon fertilizers in Example 1 and Examples 16 to 17 was calculated, and the results are shown in Table 2.

[0121] Table 2

[0122]

[0123]

[0124] Formula (1) is used to calculate the basic heat (Q1) required to heat coal gangue, where C represents the specific heat capacity of coal gangue (1.24×10 J / kg·K), m is the mass of coal gangue, and Δt is the temperature difference between the final temperature of coal gangue and the ambient temperature. This formula reflects that the energy required per unit mass of coal gangue is proportional to the temperature change during the heating process.

[0125] Formula (2) estimates the heat consumed in the insulation process, where P represents the thermal power, η1 represents the insulation efficiency (average is 0.7), and the KAΔT / d term describes the heat conduction process, where K is the thermal conductivity (0.3w / m·K), A is the heated area of ​​the gangue (2.67m), ΔT is the temperature difference, and d is the material thickness (0.667m). This formula helps to calculate the additional energy required to compensate for the heat conduction loss during the baking process.

[0126] Equation (3) estimates the useful work (Qe) as the sum of the basic heat required to heat the gangue (Q1) and the energy lost due to heat conduction (Q2).

[0127] Formula (4) calculates the total energy demand (Q T ), where η2 is the thermal conversion efficiency (average is 0.6) and η3 is the baking efficiency (average is 0.9).

[0128] Will J = 0.8 yuan total energy cost, Table 2 shows the energy consumption and additive cost of preparing coal gangue-based silicon fertilizer under different conditions. It can be seen from Table 2 that the total cost required to prepare qualified silicon fertilizer with sodium carbonate as the additive is relatively low, and the effective silicon content is high.

[0129] Q1=CmΔt——-(1)

[0130]

[0131] Q. =Q1+Q2-----------(3)

[0132]

[0133] In order to explore the effective silicon content of silicon fertilizer prepared by coal gangue and different additives (sodium carbonate, potassium carbonate, calcium carbonate) under different conditions, Examples 18 to 20 were designed.

[0134] Embodiment 18

[0135] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0136] S1. Prepare coal gangue and calcium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and calcium carbonate through a 100-mesh sieve;

[0137] S2. The pretreated coal gangue and calcium carbonate are mixed in a mass ratio of 9:1, 8:2, 7:3 or 6:4, and then the temperature is increased at a rate of 8°C / min to a holding temperature of 700°C, 800°C, 900°C, 1000°C or 1100°C for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0138] Embodiment 19

[0139] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0140] S1. Prepare coal gangue and potassium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and potassium carbonate through a 100-mesh sieve;

[0141] S2. The pretreated coal gangue and potassium carbonate are mixed in a mass ratio of 9:1, 8:2, 7:3 or 6:4, and then the temperature is increased by 8°C / min to a holding temperature of 400°C, 500°C, 600°C, 700°C or 800°C for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0142] Embodiment 20

[0143] A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption comprises the following steps:

[0144] S1. Prepare coal gangue and sodium carbonate, crush, screen and dry the coal gangue to obtain pretreated coal gangue, and pass the pretreated coal gangue and sodium carbonate through a 100-mesh sieve;

[0145] S2. The pretreated coal gangue and sodium carbonate are mixed in a mass ratio of 9:1, 8:2, 7:3 or 6:4, and then the temperature is increased at a rate of 8°C / min to a holding temperature of 400°C, 500°C, 600°C, 700°C or 800°C for 3 hours to convert silicon dioxide into effective silicon to obtain silicon fertilizer.

[0146] Figure 2 This is a comparison chart of the effective silicon content of the silicon fertilizer when the auxiliary agent is calcium carbonate in Example 18; Figure 3 This is a comparison chart of the effective silicon content of silicon fertilizer when the auxiliary agent is potassium carbonate in Example 19; Figure 4 This is a comparison chart of the effective silicon content of silicon fertilizer when the auxiliary agent is sodium carbonate in Example 20. Figure 2 to Figure 4 It can be seen that additives play a vital role in the preparation of silicon fertilizers; under the same conditions, the effective silicon content in silicon fertilizers prepared with sodium carbonate and potassium carbonate as additives is better than that with calcium carbonate as additive. Considering factors such as the consumption of coal gangue and temperature and energy consumption, sodium carbonate is the best additive.

[0147] When Example 1 uses coal gangue from different regions to prepare silicon fertilizer, the main components of the coal gangue before and after roasting are shown in Table 3, and the XRD spectra of the coal gangue before and after roasting are shown in Table 3. Figure 5 shown.

[0148] Figure 5 The XRD spectra of coal gangue from different regions before and after roasting, where (a) is before roasting and (b) is after roasting. Figure 5 (a) shows that the coal gangue before roasting is composed of kaolinite, quartz, aluminum oxide and other substances. Figure 5 From (b), it can be seen that the characteristic peaks of kaolinite and silica are significantly lowered, while the characteristic peak of sodium carbonate is significantly increased; the gangue in different regions has the same changes, indicating that this method is universal.

[0149] Table 3 Main component contents of coal gangue silicon fertilizer in different regions before and after preparation

[0150]

[0151]

[0152] Note: The numerical unit in the table is "%".

[0153] Figure 6The simulation calculation results of the roasting reaction (200-1000°C) of coal gangue with different additives (sodium carbonate, calcium carbonate and potassium carbonate) are shown in the figure. The change of Gibbs free energy of the reaction between coal gangue and three different carbonate additives in the temperature range of 200°C to 1100°C is shown. It can be seen that with the increase of temperature, the Gibbs free energy of all reactions gradually decreases, and eventually becomes negative, indicating that the reaction proceeds spontaneously at high temperature. Specifically, the Gibbs free energy of the reaction between coal gangue and sodium carbonate is the lowest in the entire temperature range, showing a large negative value, which means that this reaction is the most spontaneous and easy to proceed at all temperatures. In contrast, the reaction between coal gangue and potassium carbonate is second, while the reaction between coal gangue and calcium carbonate has the highest Gibbs free energy and the greatest reaction difficulty.

[0154] As a by-product of the coal industry, gangue is usually regarded as waste. By converting it into silicon fertilizer, we not only reduce the accumulation of waste, but also convert it into valuable products and realize the reuse of resources. In the preparation process, by precisely controlling the roasting temperature and time, and selecting suitable additives, energy consumption and pollutant emissions can be minimized while avoiding excessive energy consumption. In the prepared silicon fertilizer, the concentration of toxic metals and ions is strictly controlled at a low level, so as not to cause harm to the soil and plants. The state encourages the resource utilization of solid waste such as gangue, and relevant policy support also provides a good policy environment for the production of gangue-based silicon fertilizer.

[0155] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing silicon fertilizer for improving the effective silicon conversion rate of coal gangue and reducing energy consumption, characterized in that the steps include: The coal gangue and the additive are mixed and roasted to obtain the silicon fertilizer; The auxiliary agent includes at least one of carbonates containing potassium, calcium, magnesium, sodium and lithium.

2. The preparation method according to claim 1, characterized in that The coal gangue and the additive are sieved through a 1-200 mesh sieve before being mixed.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the coal gangue to the additive is 20:1 to 1:

1.

4. The preparation method according to claim 1, characterized in that: The calcination treatment is carried out at a temperature of 200 to 1500° C. and for a time of 0 to 12 hours, and is not 0.

5. A silicon fertilizer obtained by the preparation method according to any one of claims 1 to 4.

6. A method for improving the effective silicon conversion rate of coal gangue when preparing silicon fertilizer from coal gangue, characterized in that the steps include: The gangue and the additive are mixed and roasted; The auxiliary agent includes at least one of carbonates containing potassium, calcium, magnesium, sodium and lithium.

7. An application of the method according to claim 6 in preparing silicon fertilizer from coal gangue to increase the effective silicon content of silicon fertilizer.

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