Method for preparing carbon-silicon material by cooperatively treating solid wastes and minerals through microorganisms

Abstract

The invention belongs to the technical field of solid waste and mineral recycling, and particularly relates to a method for preparing a carbon-silicon material by cooperatively treating solid waste and mineral through microorganisms, which comprises the following steps: carrying out crushing and acid leaching pretreatment on silicon-containing solid waste / mineral to obtain a treated solid reactant; mixing with agricultural and forestry wastes, and naturally fermenting to obtain an organic-solid waste / mineral complex; treating the organic-solid waste / mineral complex by adopting a segmented heating carbon thermal reduction method to obtain a silicon carbide material; or reducing the organic-solid waste / mineral complex by adopting a magnesiothermic reduction method to obtain the silicon powder material. Microbiota generated by composting and silicon-containing solid wastes / minerals are mixed and cultured, organic matters and the silicon-containing solid wastes / minerals are decomposed, the silicon-containing solid wastes / minerals are decomposed and pores are formed by utilizing the decomposition effect of the microbial flora, and meanwhile, organic matters such as agricultural and forestry wastes are decomposed into micromolecular soluble organic matters by utilizing microorganisms; and further dissolving impurity elements in the silicon-containing solid waste / mineral to realize silicon purification.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste and mineral resource utilization, and specifically relates to a method for preparing carbon silicon materials by using microorganisms to collaboratively process solid waste and minerals. Background Art

[0002] In recent years, with the continuous development of industry and the improvement of environmental quality requirements, the high-value treatment of minerals, tailings and other silicon-containing solid wastes has become a major demand. Non-metallic element silicon is the most important element among them, and silicon oxides usually account for 70% or more of the mass ratio. Therefore, the resource utilization of silicon is a key part of the high-value treatment of minerals and silicon-containing solid wastes. At the same time, agricultural and forestry wastes are common bulk solid wastes in life. They are mainly composed of organic matter and have a high carbon content. It is highly feasible to use them as a carbon source. High-value treatment means converting solid waste into high-value materials. Considering the high carbon and silicon content of the selected materials, it is feasible to convert them into silicon carbide or silicon materials.

[0003] Silicon carbide is one of the hardest materials known, with high mechanical strength, very high thermal and chemical stability, high melting point and oxidation resistance, which makes it very attractive in high-tech applications such as electronic devices, sensors, catalysis and biotechnology. Silicon materials are important semiconductor materials. Silicon materials with high purity and excellent electrical and mechanical properties are widely used in the electronics industry. At present, many technologies have been developed or applied to the synthesis of silicon carbide and silicon materials, mainly using chemical silicon sources and carbon sources. Although silicon carbide and silicon materials can be prepared, the expensive and unsustainable raw materials and low yield are a problem for the commercialization of these methods. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing carbon silicon materials by using microorganisms to synergistically treat solid waste and minerals, and at the same time provide a solution to the problem of high value-added utilization of agricultural and forestry wastes, silicon-containing solid wastes, etc.

[0005] The present invention is achieved through the following technical solutions: A method for preparing carbon silicon materials by using microorganisms to collaboratively process solid waste and minerals comprises the following steps: S1. Pre-treating silicon-containing solid waste / minerals by crushing and acid leaching to obtain treated solid reactants; mixing the solid reactant with agricultural and forestry waste to obtain a mixture; S2, allowing the mixture in S1 to ferment naturally, and spraying water regularly to keep the surface of the mixture moist, and after a period of fermentation reaction, an organic-solid waste / mineral complex is obtained; S3, using a stepwise temperature-raising carbon thermal reduction method to treat the organic-solid waste / mineral complex to obtain silicon carbide material, specifically: First, the organic matter in the organic-solid waste / mineral complex is carbonized; Then, the carbonized carbon reacts with the silicon oxide contained in the silicon-containing solid waste / mineral to obtain a product containing silicon carbide. Then the temperature is lowered, air is introduced to burn off excess carbon, and the product is acid-washed to remove impurities to obtain silicon carbide; Alternatively, the organic-solid waste / mineral complex is reduced by magnesium thermal reduction method, and the silicon powder material is obtained after calcination, acid washing to remove impurities and calcination to remove carbon.

[0006] Further, in S1, the silicon-containing solid waste / mineral is crushed and pre-treated by acid leaching to obtain a treated solid reactant, specifically: The silicon-containing solid waste / mineral is first crushed, and the metal elements harmful to the growth of microorganisms in the crushed silicon-containing solid waste / mineral are leached out with an acidic solution, and the solid is separated to obtain a reactant.

[0007] Furthermore, in S1, the ratio of agricultural and forestry waste to silicon-containing solid waste / minerals is specifically as follows: Agricultural and forestry wastes provide carbon and nitrogen sources, the C:N ratio in the agricultural and forestry wastes is maintained at 25:1~30:1, and silicon-containing solid waste / mineral reactants provide silicon sources; they are mixed at an atomic ratio of C:Si=1.5:1~2:1.

[0008] Further, in S2, during the natural fermentation process, the humidity was maintained between 60% and 70%, adequate ventilation was maintained, and the temperature was kept in an incubator; After 30 to 40 days of reaction, the solid-liquid mixture after the reaction is completed is taken out, and the solid phase is freeze-dried and ground after centrifugation to obtain an organic-solid waste / mineral complex.

[0009] Further, in S3, the stepwise heating carbon thermal reduction method is specifically: Under a protective atmosphere, the organic-solid waste / mineral complex is first subjected to carbonization reaction at 600°C to 610°C for 1 to 1.5 hours to promote carbonization of organic matter into activated carbon; Subsequently, the temperature is raised to 1450-1500°C for 1-1.5 hours to react the activated carbon with silicon oxide to form silicon carbide; Then, the temperature is lowered to 600°C to 610°C and air is introduced to calcine for 0.5 to 1 hour to remove the residual carbon; Finally, soak in acid solution for 2 to 4 hours and then centrifuge and dry to obtain silicon carbide.

[0010] Furthermore, the acid solution is hydrochloric acid.

[0011] Further, in S3, the magnesium thermal reduction method is specifically: The organic-solid waste / mineral complex is calcined at 650-700°C for 1-1.5 hours to remove carbon therein and achieve pore formation; The decarbonized solid is mixed with magnesium particles, calcined at 650-700°C for 1-1.5 hours under a protective atmosphere, soaked in acid solution for 2-4 hours, and then centrifugally dried to obtain silicon powder material.

[0012] Furthermore, in S3, before the carbon thermal or magnesium thermal reaction, the organic-solid waste / mineral complex is pre-crushed to a particle size of less than 100 mesh; the particle size of the magnesium particles is 100-400 mesh.

[0013] Furthermore, silicon-containing solid waste / minerals are solid substances mainly composed of silicon oxides, including one or more of silicate minerals, silicon-containing tailings, coal gangue, fly ash, coal gasification slag, cement concrete and bio-silicon crust.

[0014] Furthermore, the agricultural and forestry wastes include one or more of dry fallen leaves, grass clippings, straw, corn cobs and rice husks.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The invention discloses a method for preparing carbon silicon materials by using microorganisms to synergistically treat solid waste and minerals. The method comprises the following steps: using a microbial community generated by composting agricultural and forestry wastes and co-culturing silicon-containing solid waste / minerals, allowing the microorganisms to adapt to the environment and then decompose organic matter and silicon-containing solid waste / minerals; utilizing the decomposition effect of the microbial community to decompose large particles of silicon-containing solid waste / minerals and create pores; and utilizing microorganisms to decompose organic materials such as agricultural and forestry wastes into small molecular soluble organic matter, thereby promoting further dissolution of impurity elements in silicon-containing solid waste / minerals to achieve silicon purification, and promoting better contact between silicon and carbon elements, thereby obtaining a uniformly mixed organic-silicon-containing solid waste / mineral complex, which is convenient for the later preparation of silicon carbide and silicon materials.

[0016] The present invention uses biological means to react microorganisms with cheap raw materials such as agricultural and forestry wastes and silicon-containing solid wastes to prepare silicon carbide and silicon materials. The process is simple and clear, and silicon elements are extracted, enriched and purified from silicon-containing solid wastes / minerals to form silicon carbide and silicon materials. It can provide a green, feasible, clean and environmentally friendly microbiological method for resource utilization and high-value treatment of silicon-containing solid wastes / minerals. The present invention provides a method for preparing high-value materials using microorganisms and silicon-containing solid wastes / minerals, agricultural and forestry wastes and other cheap and easily available solid wastes as raw materials, providing a new, simple, easy and low-cost idea for the preparation of silicon carbide and silicon materials.

[0017] Furthermore, the staged temperature carbon thermal reduction method has the following effects: Silicon carbide is extracted from organic-solid waste / mineral complexes, converting what might have been waste into valuable silicon carbide products. The silicon oxide and organic components in the complex are effectively utilized. After the organic matter is carbonized to form activated carbon, it reacts with silicon oxide to form silicon carbide, converting the components in the raw materials into useful products to the greatest extent, reducing resource waste compared to traditional methods.

[0018] By cooling to 600℃-610℃ and calcining with air for 0.5-1 hour, the residual carbon can be effectively removed. Then, it is soaked in acid to further remove impurities, thereby improving the purity of silicon carbide and enabling it to better meet the application needs in high-end fields such as semiconductors and ceramics.

[0019] Precisely controlling the temperature and reaction time in stages helps to form a high-quality silicon carbide crystal structure. In the 1450-1500℃ reaction stage, the appropriate temperature and time allow the activated carbon and silicon oxide to react fully and orderly, which is conducive to the formation of silicon carbide with good crystallinity and stable performance, and improves its physical and chemical properties such as mechanical properties and thermal stability.

[0020] Carrying out the carbonization reaction under a protective atmosphere avoids the generation of large amounts of harmful gases such as carbon dioxide and carbon monoxide from the reaction of organic matter with oxygen in the air during the carbonization process. In addition, the temperature of the calcination and carbon removal step is relatively low, which reduces the emission of greenhouse gases such as carbon dioxide compared to high-temperature aerobic calcination.

[0021] Acid soaking is the last step and is carried out after most of the impurities and residual carbon have been removed. Since there are relatively few impurities to be treated, the amount of acid required can be relatively reduced, and the acid is used more efficiently, reducing the risk of environmental pollution caused by improper acid treatment.

[0022] Further, the magnesium thermal reduction method has the following effects: Through a series of processing steps, silicon powder materials are successfully extracted from organic-solid waste / mineral complexes. This method provides an effective way to recover silicon resources from waste, which is of great significance for the reuse of solid waste containing silicon components and is conducive to alleviating the contradiction between supply and demand of silicon resources. The organic-solid waste / mineral complex that might have been treated as garbage is converted into economically valuable silicon powder materials.

[0023] First, the carbon in the composite is removed by calcination at 650-700℃, and then it is soaked in acid. This double impurity removal process can effectively remove organic impurities and other metal impurities in the composite to obtain relatively pure silicon powder material.

[0024] The particle size and pore structure of silicon powder can be controlled to a certain extent by calcining at a specific temperature (650-700℃) and time (1-1.5 hours). The pore-forming step may make silicon powder have better adsorption performance or performance as a carrier, while the appropriate calcination conditions help to form silicon powder with a more reasonable particle size distribution, so that it can better meet the requirements of different industrial applications for silicon powder particle characteristics.

[0025] Calcination under a protective atmosphere avoids the large-scale reaction of raw materials with oxygen in the air to produce greenhouse gases such as carbon dioxide during the high-temperature process. At the same time, the early carbon removal step is also carried out at a relatively low temperature. Compared with some high-temperature and oxygen-involved treatment methods, this method reduces carbon emissions to a certain extent.

[0026] Since the previous decarbonization and calcination process has removed most of the impurities, the acid soaking is mainly for a small amount of remaining impurities, so the amount of acid required is relatively small. This not only reduces the cost of acid use, but also reduces the difficulty and environmental risks of subsequent acid treatment, which is beneficial to environmental protection.

[0027] Furthermore, before the carbon thermal or magnesium thermal reaction, the organic-solid waste / mineral complex is pre-crushed. Generally, this operation is completed by grinding, which serves to make the raw materials of different components more uniform during the thermal reaction and the product better. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the XRD change diagram of gold tailings before and after composting; Figure 2 These are SEM images of gold tailings and agricultural and forestry waste before and after composting; Figures a, b, and c are SEM images of gold tailings before composting; Figures d, e, and f are SEM images of gold tailings after composting; Figure 3 This is the XRD diagram of silicon material prepared before and after gold tailings composting; Figure 4 This is the XRD diagram of silicon carbide prepared before and after gold tailings composting; Figure 5 It is a diagram of the composting process of agricultural and forestry waste and gold tailings; Figure 6 The SEM images of montmorillonite and agricultural and forestry waste before and after composting, where Figures a, b, and c are SEM images of montmorillonite before composting, and Figures d, e, and f are SEM images of montmorillonite after composting; Figure 7 This is the XRD diagram of silicon carbide prepared before and after montmorillonite composting; Figure 8 It is the XRD change of fine residue before and after composting; Fig. 9Figure 5 is the SEM changes of fine residue before and after composting, where Figures a, b, and c are the SEM images of fine residue before composting; Figures d, e, and f are the SEM images of fine residue after composting. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clear, the following is further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, not all embodiments.

[0030] The components described and shown in the drawings and embodiments of the present invention may be arranged and designed in various configurations. Therefore, the detailed description of the embodiments of the present invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely represents a selected embodiment of the present invention. Based on the drawings and embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0031] The features and performances of the present invention are further described in detail below in conjunction with the embodiments.

[0032] The present invention discloses a method for preparing carbon silicon material by using microorganisms to collaboratively treat solid waste and minerals, comprising the following steps: 1) After crushing the silicon-containing solid waste / mineral to a particle size of less than 100 mesh, an acidic solution is used to leach out the metal elements harmful to the growth of microorganisms, and the solid is separated to obtain a reactant; the solid reactant is mixed with agricultural and forestry waste with a C:N ratio of 25:1~30:1 at an atomic ratio of C:Si=1.5:1~2:1 to obtain a mixture.

[0033] Silicon-containing solid waste / minerals refer to solid materials mainly composed of silicon oxides, including but not limited to silicate minerals, silicon-containing tailings, coal gangue, fly ash, coal gasification slag, cement concrete, bio-silicon crust, etc.

[0034] Agricultural and forestry waste generally includes: dry fallen leaves, grass clippings, straw, corn cobs, rice husks and other common agricultural wastes.

[0035] 2) Spray water regularly to keep the humidity of the mixture between 60% and 70%, maintain sufficient ventilation and keep warm in an incubator, so that the mixture in S1 can ferment naturally. After 30 to 40 days of reaction, take out the solid-liquid mixture after the reaction is completed, freeze-dry and grind the solid phase after centrifugation to obtain an organic-solid waste / mineral complex.

[0036] 3) Using the staged temperature carbon thermal reduction method, under a protective atmosphere, the organic-solid waste / mineral complex is first carbonized at 600-610°C for 1-1.5 hours to promote the carbonization of organic matter into activated carbon, and then the temperature is raised to 1450-1500°C for 1-1.5 hours to react the activated carbon with silicon oxide to form silicon carbide, and then the temperature is lowered to 600-610°C and air is introduced for calcination for 0.5-1 hour to remove residual carbon; finally, it is soaked in acid solution for 2-4 hours and then centrifuged and dried to obtain silicon carbide.

[0037] Alternatively, the organic-solid waste / mineral complex is calcined at 650-700°C in a muffle furnace for 1-1.5 hours to remove carbon, achieve pore formation, and make subsequent reactions more fully contacted. The decarbonized solid is mixed with magnesium particles with a particle size of 100-400 mesh, calcined at 650-700°C for 1-1.5 hours under a protective atmosphere, soaked in acid for 2-4 hours, and then centrifuged and dried to obtain silicon powder material.

[0038] Therefore, compared with traditional methods, the use of microorganisms to interact with agricultural and forestry wastes, minerals, and silicon-containing solid wastes to prepare silicon carbide and silicon materials through thermal reduction reactions has cheap raw materials and can achieve continuous supply, which is a potential substitute for traditional raw materials. The combination of microorganisms with agricultural and forestry wastes, minerals, and silicon-containing solid wastes, mild conditions, and the production of high-value materials and biotechnology has shown people a beautiful blueprint. It will bring revolutionary changes to green biomaterials in the new era and provide guarantees for the improvement of human health and living environment. A series of emerging technology industry clusters will be formed around this field, bringing huge economic and social benefits to people.

[0039] The present invention is further described below in conjunction with specific implementation cases: Embodiment 1: A method for preparing silicon carbide and silicon materials by composting agricultural and forestry waste and gold tailings, specifically comprising the following steps: 1) Crush and mix agricultural and forestry wastes including fallen leaves, corn cobs, grass clippings, etc. at a mass ratio of carbon to nitrogen of 25:1; 2) Mix the well-proportioned agricultural and forestry waste with the gold tailings after acid leaching at a molar ratio of Si:C of 1:1.5, maintain the humidity between 60% and 70%, keep ventilation and keep warm in an incubator. Allow the microorganisms to use the agricultural and forestry waste as a nutrient source and weather and decompose the tailings. After a period of reaction, the tailings pile becomes fluffy, and the product is harvested to obtain an organic-tailings solid phase product; 3) The organic-tailings solid phase product is first carbonized at 600°C for 1 hour under the condition of passing argon gas to promote the carbonization of organic matter into activated carbon, and then the temperature is programmed to 1450°C for reaction for 1 hour, and then the temperature is further programmed to cool to 600°C and calcined for 0.5 hour under the condition of passing air to remove residual carbon; finally, it is soaked in 1 mol / L HCl for 2 hours and then centrifuged and dried to obtain silicon carbide material.

[0040] The organic-tailings solid phase product obtained in 2) was calcined at 700°C in a muffle furnace for 1 hour to remove the carbon therein. Subsequently, fine metal magnesium particles were added to the decarbonized solid, mixed and placed in a covered crucible, and thermally reduced at 650°C in an argon atmosphere of a tubular furnace for 1 hour. After the reaction, it was acid-washed with 1 mol / L HCl for 2 hours, and then centrifuged and freeze-dried to obtain a silicon material.

[0041] In this embodiment, a reaction system is formed with agricultural and forestry waste and gold tailings, microorganisms are cultivated with agricultural and forestry waste as a nutrient source, and a variety of microorganisms grown in the composting process are used to weather and decompose the gold tailings to activate the silicon element therein. Microbial metabolites and decomposition products of agricultural and forestry waste are used as carbon sources, and the activated silicon in the tailings is used as a silicon source, so that silicon carbide or silicon materials can be further prepared.

[0042] Figure 1 This is the XRD change diagram of gold tailings before and after composting. From the XRD results, it can be seen that the diffraction peak intensity of the gold tailings after composting is increased compared with the original gold tailings, indicating that the microorganisms produced during the composting process are better at using the amorphous components in the minerals as a source of nutrition, resulting in a relative increase in the crystalline phase components of the minerals, indicating that the microorganisms produced by the composting have a certain weathering effect on the gold tailings.

[0043] Figure 2 This is the SEM change diagram of gold tailings and agricultural and forestry waste before and after composting: Figure 2 Figures a, b, and c are SEM images of gold tailings before composting; Figure 2 Figures d, e, and f are SEM images of gold tailings after composting. Figure 2 It can be seen that the surface of the original ore is relatively smooth, composed of block and flaky structures, with sharp edges, and loose distribution of fine particles around the large block structures. The surface of the gold tailings after composting is attached by microorganisms to form a biofilm, and the minerals are broken down into fragments. The particles are small and uniform, and almost all of them are bonded together by bacterial secretions to form particle aggregates. Due to bacterial erosion, a large number of pits and even frame structures appear. The surface changes from smooth to rough, and the edges are almost arc-shaped. The organic matter secreted by bacteria deeply and evenly wraps the tailings particles.

[0044] Figure 3This is the XRD diagram of the preparation of silicon materials before and after gold tailings composting. The original ore is the gold tailings that have not been composted, and the composted tailings refer to the tailings that have been calcined and decarbonized after composting with agricultural and forestry wastes. Figure 3 It can be seen that after the original ore and the composted ore were subjected to thermal reduction reaction under the same conditions, the experimental product using the composted gold tailings as raw materials formed Si materials, but the product of the control group using the original tailings as raw materials was still mainly SiO2.

[0045] Figure 4 This is the XRD diagram of silicon carbide prepared from gold tailings after composting. The original ore is the gold tailings that have not been composted. The results show that under the same experimental conditions, the gold tailings after composting reaction can form SiC, but the original tailings without composting cannot form SiC.

[0046] Figure 5 Figures a and b in the figure are both diagrams of the composting process of agricultural and forestry waste and gold tailings. It can be seen that hyphae grow on the surface of the tailings, indicating that the microorganisms produced in the composting process have strong adaptability to adverse environmental conditions and show strong initiative. They can use the organic matter produced by agricultural and forestry waste as a source of nutrition for growth. In this process, the screening, domestication and cultivation of microorganisms are completed simultaneously, and these well-grown microorganisms can be better utilized later.

[0047] Embodiment 2: A method for preparing silicon carbide and silicon materials by composting agricultural and forestry waste and silicate mineral montmorillonite, specifically comprising the following steps: 1) Crush and mix agricultural and forestry waste including dry fallen leaves, grass clippings, straw, etc. at a mass ratio of carbon to nitrogen of 30:1; 2) Mix the well-proportioned agricultural and forestry waste with montmorillonite at a molar ratio of Si:C of 1:2, keep the humidity at about 70%, keep it well ventilated and place it in an incubator. Allow the microorganisms to use the agricultural and forestry waste as a nutrient source to weather and decompose the montmorillonite. After 40 days of reaction, it is found that the pile becomes fluffy and fully decomposed. The product is harvested and centrifuged to obtain an organic-mineral solid phase product; 3) The organic-mineral solid phase product is first carbonized at 610°C for 1.5 hours under the condition of passing argon gas to promote the carbonization of organic matter into activated carbon, and then the temperature is programmed to 1500°C for reaction for 1.5 hours, and then the temperature is further programmed to cool to 610°C and calcined for 0.5 hours in air to remove residual carbon; finally, it is soaked in 1 mol / L HCl for 2 hours and then centrifuged and dried to obtain silicon carbide material.

[0048] In this embodiment, a reaction system is formed with agricultural and forestry wastes and montmorillonite, microorganisms are cultivated with agricultural and forestry wastes as a nutrient source, and the montmorillonite is weathered and decomposed by various microorganisms grown during the fermentation process to activate the silicon element therein. The organic matter in the microorganisms is used as a carbon source, and the activated silicon in the montmorillonite is used as a silicon source, so that silicon carbide or silicon materials can be further prepared.

[0049] Figure 6 This is the SEM change diagram of montmorillonite and agricultural and forestry waste before and after composting. Figure 6 Figures a, b, and c are SEM images of montmorillonite before composting. Figure 6 Figures d, e, and f are SEM images of montmorillonite after composting. The results show that the microbial community produced by composting has a weathering effect on montmorillonite. Before composting, montmorillonite is a curled sheet aggregate. After composting, many fine particles produced during the weathering process are scattered on the surface of montmorillonite. These tiny fragments are more easily weathered and utilized by microorganisms. In addition, after the reaction, bacterial extracellular secretions are almost evenly distributed on the surface of montmorillonite, and the montmorillonite is cemented together by them to form floccules of different sizes. There is also a clear action boundary line in the larger aggregates.

[0050] Figure 7 This is the XRD diagram of silicon carbide prepared by montmorillonite composting. Figure 7 It was concluded that after the composted montmorillonite was subjected to thermal reduction reaction, SiC with high purity and good crystallinity was generated. This is because, on the one hand, during the composting process, microorganisms weathered the montmorillonite, making its structure loose, leaving pits on the surface of the mineral, increasing the contact area with the mineral, and the microbial secretions evenly covered the montmorillonite surface, serving as a carbon source for the subsequent preparation of SiC; on the other hand, microorganisms activated the silicon element in the montmorillonite, making it easier to use than the original ore as a silicon source for the preparation of SiC.

[0051] Embodiment 3: A method for preparing silicon carbide and silicon materials by composting agricultural and forestry waste and coal gasification slag, specifically comprising the following steps: 1) Crush and mix agricultural and forestry wastes including fallen leaves, corn cobs, grass clippings, etc. at a mass ratio of carbon to nitrogen of 25:1; 2) Mix the coal gasification slag fines with the well-proportioned agricultural and forestry wastes at a molar ratio of Si:C of 1:2, keep the humidity at about 65%, keep ventilation and keep warm in an incubator. Let the growing microorganisms use the agricultural and forestry wastes as a nutrient source to weather and decompose the fines. After about 40 days of reaction, harvest the product to obtain an organic-fines solid phase product; 3) The organic-fine slag solid phase product is first carbonized at 605°C for 1 hour under the condition of passing argon gas to promote the carbonization of organic matter into activated carbon, and then the temperature is programmed to 1450°C for reaction for 1 hour, and then the temperature is further programmed to decrease to 600°C and calcined for 0.5 hour under the condition of passing air to remove residual carbon; finally, it is soaked in 1 mol / L HCl for 2 hours and then centrifuged and dried to obtain silicon carbide material.

[0052] 4) The organic-fine slag solid phase product obtained in 2) was calcined at 650°C for 1 hour in a muffle furnace to remove the carbon therein. Subsequently, 300 mesh magnesium particles were added to the decarbonized solid, mixed and placed in a covered crucible, and subjected to thermal reduction reaction at 700°C in an argon atmosphere of a tubular furnace for 1 hour. After the reaction, the solid was acid-washed with 1 mol / L HCl for 2 hours, and then centrifuged and freeze-dried to obtain a silicon material.

[0053] Figure 8 This is the XRD change of fine slag before and after composting. It can be seen from the figure that the fine slag has a wide scattering peak and a high background, indicating that the sample has an amorphous component and the main crystalline phase is quartz. After composting, the quartz peak intensity in the fine slag is slightly weakened and the crystallinity is reduced, indicating that the fine slag structure is destroyed to a certain extent and the amorphous structure increases. This is because the weathering of the fine slag by the microbial community reduces the crystalline component.

[0054] Fig. 9 is the SEM change of fine residue before and after composting, Fig. 9 Figures a, b, and c are SEM images of fine residue before composting; Fig. 9 Figures d, e, and f are SEM images of fine slag after composting. It can be seen that the fine slag structure is mostly spherical with regular shape and different sizes, smooth surface, and no broken. It may be silicon dioxide wrapped in amorphous metal oxides, which is consistent with the XRD results. After composting, the fine slag spheres are more concentrated, and the surface becomes irregular due to bacterial etching, with a large number of small holes. Some microspheres even disappear to form fine particle agglomerates, and the substrate material presents an uneven shape. The composting microbial community can weather the fine slag to a certain extent.

[0055] In summary, the organic-silicon-containing solid waste / mineral complexes after co-composting of silicon-containing tailings, silicate minerals, coal gasification fine slag and agricultural and forestry wastes can be used to prepare SiC or Si materials, which provides a new idea for the high value of silicon-containing solid waste / minerals and agricultural and forestry wastes.

[0056] With the development of industry and the continuous improvement of national environmental quality requirements, the resource utilization, reduction and harmless treatment of silicon-containing solid waste has become a major demand. Compared with the metal elements in it, non-metallic element silicon is the most important element, and silicon oxides often account for 70% or even higher. Therefore, the resource utilization of silicon in silicon-containing solid waste is a key part of its reduction and resource utilization. Further development of it as a high-value functional material is an important topic that crosses multiple disciplines such as mineralogy, environment, energy, materials, and chemical engineering, and has both scientific significance and economic value.

[0057] The present invention uses biological means to utilize a variety of composite microorganisms produced by agricultural and forestry wastes to achieve the enrichment of silicon in silicon-containing solid wastes / minerals, and then converts them into high-value materials - silicon carbide and silicon materials, thereby realizing the resource utilization and high value of agricultural and forestry wastes and silicon-containing solid wastes / minerals, and providing a green, feasible, clean and environmentally friendly biological method for the treatment of silicon-containing solid wastes / minerals.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing carbon silicon materials by using microorganisms to collaboratively treat solid waste and minerals, characterized in that: The following steps are involved: S1. Pre-treating silicon-containing solid waste / minerals by crushing and acid leaching to obtain treated solid reactants; mixing the solid reactant with agricultural and forestry waste to obtain a mixture; S2, allowing the mixture in S1 to ferment naturally, and spraying water regularly to keep the surface of the mixture moist, and after a period of fermentation reaction, an organic-solid waste / mineral complex is obtained; S3, using a stepwise temperature-raising carbon thermal reduction method to treat the organic-solid waste / mineral complex to obtain silicon carbide material, specifically: First, the organic matter in the organic-solid waste / mineral complex is carbonized; Then, the carbonized carbon reacts with the silicon oxide contained in the silicon-containing solid waste / mineral to obtain a product containing silicon carbide. Then the temperature is lowered, air is introduced to burn off excess carbon, and the product is acid-washed to remove impurities to obtain silicon carbide; Alternatively, the organic-solid waste / mineral complex is reduced by magnesium thermal reduction method, and the silicon powder material is obtained after calcination, acid washing to remove impurities and calcination to remove carbon.

2. The method for preparing carbon silicon materials by using microorganisms to collaboratively treat solid waste and minerals according to claim 1, characterized in that: In S1, the silicon-containing solid waste / mineral is crushed and pre-treated by acid leaching to obtain a treated solid reactant, specifically: The silicon-containing solid waste / mineral is first crushed, and the metal elements harmful to the growth of microorganisms in the crushed silicon-containing solid waste / mineral are leached out with an acidic solution, and the solid is separated to obtain a reactant.

3. The method for preparing carbon silicon materials by using microorganisms to collaboratively treat solid waste and minerals according to claim 1, characterized in that: In S1, the ratio of agricultural and forestry waste to silicon-containing solid waste / minerals is as follows: Agricultural and forestry wastes provide carbon and nitrogen sources, the C:N ratio in the agricultural and forestry wastes is maintained at 25:1~30:1, and silicon-containing solid waste / mineral reactants provide silicon sources; they are mixed at an atomic ratio of C:Si=1.5:1~2:

1.

4. The method for preparing carbon silicon materials by using microorganisms to collaboratively treat solid waste and minerals according to claim 1, characterized in that: In S2, during the natural fermentation process, the humidity was maintained between 60% and 70%, adequate ventilation was maintained, and the temperature was kept in an incubator; After 30 to 40 days of reaction, the solid-liquid mixture after the reaction is completed is taken out, and the solid phase is freeze-dried and ground after centrifugation to obtain an organic-solid waste / mineral complex.

5. The method for preparing carbon silicon materials by using microorganisms to collaboratively treat solid waste and minerals according to claim 1, characterized in that: In S3, the stepwise temperature-raising carbon thermal reduction method is specifically as follows: Under a protective atmosphere, the organic-solid waste / mineral complex is first subjected to carbonization reaction at 600°C to 610°C for 1 to 1.5 hours to promote carbonization of organic matter into activated carbon; Subsequently, the temperature is raised to 1450-1500°C for 1-1.5 hours to react the activated carbon with silicon oxide to form silicon carbide; Then, the temperature is lowered to 600°C to 610°C and air is introduced to calcine for 0.5 to 1 hour to remove the residual carbon; Finally, soak in acid solution for 2 to 4 hours and then centrifuge and dry to obtain silicon carbide.

6. The method for preparing carbon silicon materials by using microorganisms to collaboratively treat solid waste and minerals according to claim 5, characterized in that: The acid solution used is hydrochloric acid.

7. The method for preparing carbon silicon materials by using microorganisms to collaboratively treat solid waste and minerals according to claim 1, characterized in that: In S3, the magnesium thermal reduction method is specifically: The organic-solid waste / mineral complex is calcined at 650-700°C for 1-1.5 hours to remove carbon therein and achieve pore formation; The decarbonized solid is mixed with magnesium particles, calcined at 650-700°C for 1-1.5 hours under a protective atmosphere, soaked in acid solution for 2-4 hours, and then centrifugally dried to obtain silicon powder material.

8. The method for preparing carbon silicon materials by using microorganisms to collaboratively treat solid waste and minerals according to claim 1, characterized in that: In S3, before the carbon thermal or magnesium thermal reaction, the organic-solid waste / mineral complex is crushed in advance to make the particle size less than 100 mesh; the particle size of the magnesium particles is 100-400 mesh.

9. The method for preparing carbon silicon materials by using microorganisms to collaboratively treat solid waste and minerals according to claim 1, characterized in that: Silicon-containing solid waste / minerals are solid materials mainly composed of silicon oxides, including one or more of silicate minerals, silicon-containing tailings, coal gangue, fly ash, coal gasification slag, cement concrete and bio-silicon crust.

10. The method for preparing carbon silicon materials by using microorganisms to collaboratively treat solid waste and minerals according to claim 1, characterized in that: Agricultural and forestry wastes include one or more of dry fallen leaves, grass clippings, straw, corn cobs and rice husks.

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