Coal-based solid waste grading and quality-based utilization method
By classifying and activating coal gangue, high-quality coal gangue-based silicon fertilizer and adsorbent materials are prepared, solving the environmental pollution and resource utilization limitations caused by the high sulfur content in coal gangue, and realizing the efficient and environmentally friendly utilization of coal gangue.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XINJIANG INST OF ENG
- Filing Date
- 2026-02-05
- Publication Date
- 2026-05-01
AI Technical Summary
The high sulfur content in coal gangue leads to environmental pollution and reduced performance of building materials. Existing technologies struggle to effectively separate and utilize different mineral components, thus limiting resource utilization.
By mixing coal gangue with water and then using a hydrocyclone to classify and separate the products, the underflow and overflow products are obtained. These products are then activated and calcined to prepare coal gangue-based silicon fertilizer and adsorbent materials, thereby removing high-sulfur heavy metals and achieving relative enrichment and efficient utilization of the minerals.
This has enabled the high-value utilization of coal gangue, producing environmentally friendly fertilizers and highly efficient adsorption materials, solving the problem of heavy metal pollution, and improving resource utilization efficiency and environmental protection effectiveness.
Smart Images
Figure CN121944995A_ABST
Abstract
Description
A method for graded and classified utilization of coal-based solid waste Technical Field
[0001] This invention relates to the field of solid waste resource utilization, and in particular to a method for graded and quality-based utilization of coal-based solid waste. Background Technology
[0002] Coal, as the most important basic energy source and industrial raw material, has long supported economic and social development. However, large-scale coal mining has also generated a large amount of coal gangue. The massive accumulation of coal gangue not only occupies vast tracts of land resources, causing waste, but also poses serious harm to the surrounding environment. Therefore, the resource-based and efficient utilization of coal gangue is urgently needed.
[0003] Currently, research and application of comprehensive utilization of coal gangue mainly focus on the following aspects: First, the application of coal gangue as a building material has received widespread attention, especially in the production of cement, bricks, and lightweight aggregates. It can replace some natural ores, reduce production costs, and lower carbon emissions from cement production. Second, coal gangue can also be used for soil improvement, especially in barren or acidic soils, improving the physical and chemical properties of the soil, enhancing soil permeability and fertility, and promoting sustainable agricultural development. Furthermore, coal gangue has important uses in mine backfilling and landfilling. By filling mining pits and quarry cavities, it not only reduces environmental pollution but also effectively utilizes these wastes. The energy recovery value of coal gangue is also receiving increasing attention. Coal gangue contains certain organic matter, which, after appropriate treatment such as combustion or gasification, can be converted into electricity or other forms of energy, further reducing dependence on traditional energy sources. However, whether used for soil improvement or as a building material, the coal gangue used is mostly low-sulfur coal gangue. The presence of sulfur leads to a series of negative impacts. First, excessively high sulfur content in coal gangue can cause sulfate corrosion when reacting with building materials such as cement, reducing the durability and strength of these materials and affecting their long-term performance. Furthermore, sulfur combustion produces sulfur dioxide (SO2), which not only increases air pollution but also contributes to acid rain, further harming the environment and ecosystems. Therefore, coal gangue must be processed before it can be utilized. Summary of the Invention
[0004] This invention provides a method for graded and classified utilization of coal-based solid waste. Before resource utilization, coal gangue is graded and classified in advance to achieve relative enrichment of different mineral components, and differentiated utilization is implemented according to the properties and characteristics of various products to achieve the purpose of high-value utilization of coal gangue.
[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: The present invention provides a method for graded and classified utilization of coal-based solid waste, comprising the following steps: mixing coal gangue and water to obtain coal gangue slurry; feeding the coal gangue slurry into a hydrocyclone for graded and classified treatment to obtain underflow product and overflow product; mixing the overflow product with a first activator for activation treatment to obtain silicon fertilizer; mixing the underflow product with a second activator for calcination to obtain adsorbent material.
[0006] In some specific embodiments, the particle size of the coal gangue is <1mm.
[0007] In some specific embodiments, the concentration of the coal gangue slurry is 80~120g / L.
[0008] In some specific embodiments, the diameter of the underflow port of the hydrocyclone is 6~10mm, and the pressure at the inlet of the hydrocyclone is 0.08~0.13MPa.
[0009] In some specific embodiments, the mass ratio of the overflow product to the first activator is 10:4~6.
[0010] In some specific embodiments, the first activator includes calcium sulfate, calcium carbonate, or calcium hydroxide.
[0011] In some specific embodiments, the activation treatment temperature is 1000~1200℃, and the activation treatment time is 1~3h.
[0012] In some specific embodiments, the mass ratio of the underflow product to the second activator is 10:2~3.
[0013] In some specific embodiments, the second activator includes calcium hydroxide, sodium hydroxide, potassium hydroxide, or magnesium hydroxide.
[0014] In some specific embodiments, the calcination temperature is 700~900℃, the calcination time is 1~3h, and the calcination atmosphere is an inert gas.
[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The method for graded and classified utilization of coal-based solid waste of the present invention first prepares coal gangue and water into a slurry, and then sends it into a hydrocyclone for graded and classified treatment. The clay minerals such as kaolin in the coal gangue have strong hydrophilicity. When the coal gangue and water are fully mixed and in contact, the water molecules and the surface of the clay minerals undergo hydration, which leads to the generation of uneven expansion stress and wedge crack pressure, thereby causing the clay minerals to expand and disintegrate, forming fine mud. Other substances in the coal gangue, such as coal and pyrite, are relatively stable and not easy to mudify. They exist in the form of large particles. Therefore, there are obvious differences in particle size. By using the graded hydrocyclone, the particle size difference of different minerals is utilized to achieve the relative enrichment of different minerals, thereby achieving the purpose of graded and classified treatment, and then obtaining the underflow product with carbonaceous matter and pyrite as the main components and the overflow product with clay minerals as the main components. The overflow products were used to prepare coal gangue-based silicon fertilizer using thermal activation technology, while the underflow products were used to prepare coal gangue adsorbent materials using calcination.
[0016] (2) By utilizing the characteristics of the overflow products being rich in clay minerals, high-quality coal gangue-based silicon fertilizer is prepared to achieve the purpose of high quality and high utilization. At the same time, a pre-grading treatment technology is adopted to remove high-sulfur heavy metals such as pyrite in advance, thereby solving the problem of heavy metal pollution in coal gangue and producing environmentally friendly fertilizer to avoid secondary pollution.
[0017] (3) Coal gangue-based adsorbent materials were prepared using the underflow products through an anaerobic roasting method. Fe in pyrite 2+ It has strong reducing properties and can remove Cr from water. 6+ Reduced to less toxic Cr 3+ Coal possesses a well-developed porous structure and abundant surface-active groups, exhibiting strong adsorption capacity. By utilizing the high pyrite and coal content in the underflow products, it can be prepared into a highly efficient adsorbent material for coal gangue, applicable to water treatment and environmental remediation, achieving the goal of treating waste with waste.
[0018] This method features large processing capacity and high sorting efficiency, making it suitable for large-scale coal gangue processing. The resulting silicon fertilizer and adsorbent materials are widely used in agriculture, environmental protection, and other fields, demonstrating significant commercial value. Attached Figure Description
[0019] The above and other objects, features and advantages of the present invention will be apparent from the following description of the preferred embodiments and drawings illustrating the gist of the invention and its use, in which: Figure 1 is a process flow diagram of the present invention. Detailed Implementation
[0020] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments described below are for illustrative purposes only and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the following embodiments, conditions and methods known in the art can be used for processing.
[0021] This invention provides a method for the graded and classified utilization of coal-based solid waste. The process flow is shown in Figure 1, and includes the following steps: mixing coal gangue and water to obtain coal gangue slurry; feeding the coal gangue slurry into a hydrocyclone for graded and classified treatment to obtain underflow product and overflow product; mixing the overflow product with a first activator for activation treatment to obtain silicon fertilizer; and mixing the underflow product with a second activator for calcination to obtain adsorbent material.
[0022] The present invention relates to a method for the graded and classified utilization of coal-based solid waste. First, coal gangue is mixed with water to form a slurry, which is then fed into a hydrocyclone for grading and classification. Kaolinite and other clay minerals in the coal gangue have strong hydrophilicity. When the coal gangue and water are fully mixed and in contact, water molecules undergo hydration with the surface of the clay minerals, leading to uneven expansion stress and wedge-crack pressure. This causes the clay minerals to expand and disintegrate, forming fine mud. Other substances in the coal gangue, such as coal and pyrite, are relatively stable and not easily mud-ified, existing as large particles. Therefore, there are significant differences in particle size. Using a hydrocyclone, the grading equipment utilizes the particle size differences of different minerals to achieve relative enrichment, thus achieving the purpose of grading and classification. This results in a high-sulfur, high-carbon coal gangue as the underflow product, mainly composed of carbonaceous matter and pyrite, and a high-ash, high-clay coal gangue as the overflow product, mainly composed of clay minerals. The overflow products were used to prepare coal gangue-based silicon fertilizer using thermal activation technology, while the underflow products were used to prepare coal gangue adsorbent materials using calcination.
[0023] By utilizing the clay mineral-rich characteristics of the overflow product (high-ash, clay-rich coal gangue), it is prepared into high-quality coal gangue-based silicon fertilizer, achieving the goal of high quality and optimal use. At the same time, a pre-grading treatment technology is adopted to remove high-sulfur heavy metals such as pyrite in advance, thereby solving the problem of heavy metal pollution in coal gangue and producing environmentally friendly fertilizer, avoiding secondary pollution.
[0024] Coal gangue-based adsorbent materials were prepared using the underflow products (high-sulfur, carbon-rich coal gangue) through an anaerobic roasting method. The Fe in pyrite... 2+ It has strong reducing properties and can remove Cr from water. 6+ Reduced to less toxic Cr 3+Coal possesses a well-developed porous structure and abundant surface-active groups, exhibiting strong adsorption capacity. By utilizing the high pyrite and coal content in the underflow products, it can be prepared into a highly efficient adsorbent material for coal gangue, applicable to water treatment and environmental remediation, achieving the goal of treating waste with waste.
[0025] In some embodiments, the particle size of the coal gangue is <1 mm.
[0026] In some embodiments, the concentration of the coal gangue slurry is 80-120 g / L. For example, the concentration of the coal gangue slurry can be 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, and 120 g / L, etc.
[0027] In this invention, controlling the concentration of coal gangue slurry within the aforementioned range achieves high separation precision: at a moderate concentration, there is appropriate interference sedimentation between particles, allowing coarse particles (mainly pyrite and coarse carbonaceous matter) to effectively overcome the slurry's viscosity resistance and enter the underflow under centrifugal force, forming high-sulfur, carbon-rich coal gangue as the underflow product. Meanwhile, fine-grained clay minerals (such as kaolinite, muscovite, and other silicate minerals) are mainly discharged with the overflow, forming high-ash, clay-rich coal gangue as the overflow product. Simultaneously, at this concentration, the system ensures sufficient solids throughput without affecting economic efficiency due to excessive circulating load or high pumping energy consumption. If the coal gangue slurry concentration is too high, the slurry viscosity is too high, resulting in severe inter-particle interference and masking particle size differences. A large amount of fine clay particles are carried into the underflow due to their high viscosity, leading to increased ash and clay content in the underflow product (which should be high-sulfur, carbon-rich), and dilution of carbon and sulfur grades. Some coarse carbonaceous materials or pyrite cannot settle effectively due to slurry blockage and instead enter the overflow, leading to an increase in carbon and sulfur impurities in the overflow product (which should be rich in clay). If the concentration of the coal gangue slurry is too low, the solid content in the overflow product is too low; although pure, the quantity is small, requiring huge concentration costs and having low processing capacity, making it uneconomical. The large volume of circulating water increases water and electricity consumption and the subsequent dewatering load. The effective solids treatment capacity is low, resulting in poor equipment utilization.
[0028] In some embodiments, the underflow diameter of the hydrocyclone is 6-10 mm, and the inlet pressure of the hydrocyclone is 0.08-0.13 MPa. As an example, the underflow diameter of the hydrocyclone can be 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm, etc., and the inlet pressure of the hydrocyclone can be 0.08 MPa, 0.09 MPa, 0.1 MPa, 0.11 MPa, 0.12 MPa, and 0.13 MPa, etc.
[0029] In this invention, the underflow orifice diameter is a crucial parameter for controlling the particle size and product distribution ratio of the hydrocyclone. Within this range, the underflow orifice size is moderate, allowing coarse target particles to discharge smoothly while effectively retaining fine particles, causing them to exit through the overflow orifice. This ensures that the underflow product, primarily pyrite and residual carbon, is effectively enriched, while the ash content (mainly from clay) is relatively reduced. The overflow product is highly enriched in clay minerals (kaolinite, muscovite, and other silicate minerals), with low carbon and sulfur impurity content.
[0030] In some embodiments, the mass ratio of the overflow product to the first activator is 10:4 to 6. As examples, the mass ratio of the overflow product to the first activator can be 10:4, 10:4.2, 10:4.3, 10:4.5, 10:4.8, 10:5, 10:5.3, 10:5.5, and 10:6, etc.
[0031] In this invention, the optimal activation effect is achieved when the mass ratio of the overflow product to the first activator is within the aforementioned range, resulting in a significant increase in the effective silicon content of the product after cremation. If there is too much first activator, the excess activator cannot react fully and remains inside the silicon fertilizer product after high-temperature activation, diluting the effective silicon content and thus reducing the quality of the silicon fertilizer product (the effective silicon content in the product decreases). If there is too little first activator, the inert silicon source minerals such as kaolinite and muscovite in the overflow product cannot react fully, causing a decrease in the quality of the silicon fertilizer product (the effective silicon content in the product decreases).
[0032] In some embodiments, the first activator includes, but is not limited to, calcium sulfate, calcium carbonate, or calcium hydroxide.
[0033] In some embodiments, mixing the overflow product and the first activator further includes feeding the mixed material into a granulator for granulation.
[0034] In some embodiments, the activation treatment temperature is 1000~1200℃, and the activation treatment time is 1~3h. As examples, the activation treatment temperature can be 1000℃, 1020℃, 1050℃, 1080℃, 1100℃, 1120℃, 1150℃, 1180℃, and 1200℃, etc., and the activation treatment time can be 1h, 1.25h, 1.5h, 1.75h, 2h, 2.25h, 2.5h, 2.75h, and 3h, etc.
[0035] In this invention, the activation treatment conditions are within the range that result in the best activation and economic benefits. If the temperature is too low or the time is too short, the activation will not be sufficient and the effective silicon content will be low. If the temperature is too high or the time is too long, the energy consumption will be too high and it will be uneconomical.
[0036] In some embodiments, the mass ratio of the underflow product to the second activator is 10:2 to 3. As examples, the mass ratio of the underflow product to the second activator can be 10:2, 10:2.2, 10:2.4, 10:2.5, 10:2.6, 10:2.7, 10:2.8, 10:2.9, and 10:3, etc.
[0037] In this invention, the activation effect and economic benefits are optimal when the mass of the underflow product and the second activator are within the above-mentioned range.
[0038] In some embodiments, the second activator includes, but is not limited to, calcium hydroxide, sodium hydroxide, potassium hydroxide, or magnesium hydroxide.
[0039] In some embodiments, mixing the underflow product and the second activator further includes feeding the mixed material into a granulator for granulation.
[0040] In some embodiments, the calcination temperature is 700~900℃, the calcination time is 1~3h, and the calcination atmosphere is an inert gas. For example, the calcination temperature can be 700℃, 720℃, 750℃, 780℃, 800℃, 810℃, 850℃, 870℃, and 900℃, etc., and the calcination time can be 1h, 1.25h, 1.5h, 1.75h, 2h, 2.25h, 2.5h, 2.75h, and 3h, etc., and the inert atmosphere includes, but is not limited to, nitrogen, helium, and argon.
[0041] In this invention, the activation effect and economic benefits are optimal within this range. If the temperature is too low or the time is too short, the activation cannot be fully achieved, resulting in poor adsorption. If the temperature is too high or the time is too long, the energy consumption is too high, which is uneconomical.
[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0043] Example 1: A method for graded and classified utilization of coal-based solid waste. The process flow is shown in Figure 1, including the following steps: Coal gangue from a large coal mine in Gansu is ground to a particle size of <1mm using a coal mill to obtain coal gangue powder; the coal gangue powder is fed into a mixing tank and mixed with water to obtain a coal gangue slurry with a mass concentration of 100g / L; the coal gangue slurry is fed into a hydrocyclone and graded and classified under conditions of a bottom outlet diameter of 10mm and an inlet pressure of 0.1MPa to obtain high-ash, clay-rich coal gangue overflow product and high-sulfur, carbon-rich coal gangue underflow product; 10 parts of the overflow product and 4 parts of calcium carbonate are mixed evenly and fed into a granulator to form small balls, which are then activated in a rotary kiln at 1000℃ for 1 hour to obtain coal gangue-based silicon fertilizer.
[0044] Ten parts of underflow product and two parts of calcium hydroxide were mixed evenly and fed into a granulator to form small balls. Then, the balls were fed into a tube furnace and calcined at 700°C for 1 hour under nitrogen protection to obtain coal gangue-based adsorbent material.
[0045] The XRF analysis results of coal gangue, overflow products and underflow products in Example 1 are shown in Table 1.
[0046] Table 1. XRF analysis results of coal gangue, overflow products, and underflow products in Example 1.
[0047] Example 2: A method for graded and classified utilization of coal-based solid waste. The process flow is shown in Figure 1, including the following steps: Coal gangue from a large coal mine in Xinjiang is ground to a particle size of <1mm using a coal mill to obtain coal gangue powder; the coal gangue powder is fed into a mixing tank and mixed with water to obtain a coal gangue slurry with a mass concentration of 80g / L; the coal gangue slurry is fed into a hydrocyclone and graded and classified under conditions of a bottom outlet diameter of 6mm and an inlet pressure of 0.13Mpa to obtain high-ash, clay-rich coal gangue overflow product and high-sulfur, carbon-rich coal gangue underflow product; 10 parts of the overflow product and 6 parts of calcium carbonate are mixed evenly and fed into a granulator to form small balls, which are then activated in a rotary kiln at 1100℃ for 2 hours to obtain coal gangue-based silicon fertilizer.
[0048] Ten parts of underflow product and three parts of calcium hydroxide were mixed evenly and fed into a granulator to form small balls. Then, the balls were fed into a tube furnace and calcined at 800°C for 2 hours under nitrogen protection to obtain coal gangue-based adsorbent material.
[0049] The XRF analysis results of coal gangue, overflow products and underflow products in Example 2 are shown in Table 2.
[0050] Table 2. XRF analysis results of coal gangue, overflow products, and underflow products in Example 2.
[0051] Example 3: A method for graded and classified utilization of coal-based solid waste. The process flow is shown in Figure 1, including the following steps: Coal gangue from a large coal mine in Xinjiang is ground to a particle size of <1mm using a coal mill to obtain coal gangue powder; the coal gangue powder is fed into a mixing tank and mixed with water to obtain a coal gangue slurry with a mass concentration of 120g / L; the coal gangue slurry is fed into a hydrocyclone and graded and classified under conditions of a bottom outlet diameter of 10mm and an inlet pressure of 0.08Mpa to obtain high-ash, clay-rich coal gangue overflow product and high-sulfur, carbon-rich coal gangue underflow product; 10 parts of the overflow product and 5 parts of calcium carbonate are mixed evenly and fed into a granulator to form small balls, which are then activated in a rotary kiln at 1200℃ for 3 hours to obtain coal gangue-based silicon fertilizer.
[0052] Ten parts of underflow product and three parts of calcium hydroxide were mixed evenly and fed into a granulator to form small balls. Then, the balls were fed into a tube furnace and calcined at 900°C for 3 hours under nitrogen protection to obtain coal gangue-based adsorbent material.
[0053] The XRF analysis results of coal gangue, overflow products and underflow products in Example 3 are shown in Table 3.
[0054] Table 3. XRF analysis results of coal gangue, overflow products, and underflow products in Example 3.
[0055] Although preferred embodiments of the invention have been shown and described, it is conceivable that those skilled in the art can devise various modifications to the invention within the spirit and scope of the appended claims.
Claims
1. A method for graded and classified utilization of coal-based solid waste, characterized in that, Includes the following steps: Coal gangue and water are mixed to obtain coal gangue slurry; the coal gangue slurry is fed into a hydrocyclone for classification and separation to obtain underflow product and overflow product; the overflow product is mixed with a first activator and activated to obtain silicon fertilizer; the underflow product and the second activator are mixed and calcined to obtain adsorbent material.
2. The method for graded and classified utilization of coal-based solid waste according to claim 1, characterized in that, The particle size of the coal gangue is <1mm.
3. The method for graded and classified utilization of coal-based solid waste according to claim 1, characterized in that, The concentration of the coal gangue slurry is 80~120g / L.
4. The method for graded and classified utilization of coal-based solid waste according to claim 1, characterized in that, The diameter of the underflow inlet of the hydrocyclone is 6~10mm, and the pressure at the inlet of the hydrocyclone is 0.08~0.13MPa.
5. The method for graded and classified utilization of coal-based solid waste according to claim 1, characterized in that, The mass ratio of the overflow product to the first activator is 10:4~6.
6. The method for graded and classified utilization of coal-based solid waste according to claim 1, characterized in that, The first activator includes calcium sulfate, calcium carbonate, or calcium hydroxide.
7. The method for graded and classified utilization of coal-based solid waste according to claim 1, characterized in that, The activation treatment temperature is 1000~1200℃, and the activation treatment time is 1~3h.
8. The method for graded and classified utilization of coal-based solid waste according to claim 1, characterized in that, The mass ratio of the underflow product to the second activator is 10:2~3.
9. The method for graded and classified utilization of coal-based solid waste according to claim 1, characterized in that, The second activator includes calcium hydroxide, sodium hydroxide, potassium hydroxide, or magnesium hydroxide.
10. The method for graded and classified utilization of coal-based solid waste according to claim 1, characterized in that, The calcination temperature is 700~900℃, the calcination time is 1~3h, and the calcination atmosphere is an inert gas.