Burning-free soilless culture pisolite for ecological agriculture and preparation method of baking-free soilless culture pisolite

Abstract

The invention relates to the technical field of soilless culture pisolite, in particular to baking-free soilless culture pisolite for ecological agriculture and a preparation method of the baking-free soilless culture pisolite. 2-10 parts of gold smelting desulfurized gypsum; 0-10 parts of red mud; 5 to 15 parts of water; wherein the core solid waste powder is composed of 60-80 parts of gold tailings, 10-20 parts of fly ash and 10-20 parts of slag powder. According to the application, a large amount of industrial solid waste is taken as a core raw material, and a gel network is formed by virtue of a synergistic gelling reaction of active silica-alumina components in the slag powder and the fly ash, so that material bonding and forming are realized, and nutrient ions necessary for plants can be controllably released in cultivation. Therefore, the problems that in the prior art, the problems of high energy consumption and single function of a soilless culture substrate and the problem of low-value stockpiling pollution of gold solid waste coexist for a long time, and an effective technical path for synergistically converting the two problems is lacked are solved.

Description

Technical Field

[0001] This invention relates to the field of soilless cultivation stone technology, specifically to a non-fired soilless cultivation stone for ecological agriculture and its preparation method. Background Technology

[0002] Soilless cultivation, as a core planting model for efficient resource utilization in modern agriculture, has been widely promoted in facility agriculture and urban agriculture due to its advantages such as water and fertilizer conservation, fewer pests and diseases, and stable yields. Its cultivation effect directly depends on the water retention, aeration, and nutrient supply capacity of the substrate. Currently, mainstream soilless cultivation substrates are divided into two main categories: organic and inorganic substrates. Organic substrates, represented by coconut coir and peat, while possessing certain water retention and organic matter content, are prone to microbial degradation during long-term use, leading to substrate compaction and decreased porosity. Frequent replacement is necessary to maintain planting effects, increasing labor and material costs. Inorganic substrates are mainly composed of expanded clay, perlite, and vermiculite. Sintered expanded clay, which is widely used, requires high-temperature calcination, consuming over 500 kWh of energy per ton of product, resulting in high energy consumption and high carbon emissions. Furthermore, these traditional inorganic substrates lack nutrient supply capabilities, requiring the addition of large amounts of chemical fertilizers during cultivation, further increasing cultivation costs and failing to meet the low-carbon and high-efficiency development needs of modern agriculture.

[0003] Meanwhile, the gold mining and smelting process generates a large amount of solid waste, which has become a prominent bottleneck for the industry's sustainable development. On the one hand, the annual discharge of gold tailings exceeds 100 million tons, the main component of which is potassium-sodium feldspar (usually accounting for ≥65% by mass). It naturally contains nutrients such as potassium and sodium, which are essential for plant growth, and has potential agricultural utilization value. However, due to the dispersed particles and lack of shape-forming properties, long-term open-air storage not only occupies a large amount of land resources, but also easily causes ecological and environmental problems such as dust pollution and soil erosion. On the other hand, in order to remove sulfur from the flue gas during the gold smelting process, a large amount of desulfurization gypsum byproduct is generated. This substance is rich in elements such as sulfur and calcium, which are sources of micronutrients needed for plant growth. However, at present, this type of desulfurization gypsum is mostly disposed of by stockpiling, which not only wastes resources, but the soluble salts it contains may also leach and seep in through rainwater, causing the risk of soil salinization and threatening the surrounding ecological environment. Currently, gold tailings are mostly used in low-value-added fields such as roadbed filling, and the resource utilization rate of desulfurization gypsum is even lower. Neither has achieved high-value utilization that is precisely aligned with agricultural needs. The disposal and resource utilization of solid waste has become an urgent industry problem to be solved.

[0004] In summary, existing soilless cultivation substrates and gold waste treatment technologies face significant challenges: on one hand, there are substrates characterized by high energy consumption and limited functionality; on the other hand, there is solid waste awaiting high-value utilization and disposal. Therefore, it is necessary to break through traditional processes and raw material systems by employing a non-fired process of "roller extrusion + ball-forming rolling" to achieve the synergistic molding and functional transformation of gold tailings and desulfurized gypsum. This approach addresses the pain points of traditional substrates—high cost, high energy consumption, and limited functionality—while simultaneously disposing of solid waste, alleviating ecological pressure, and achieving a win-win situation for both industrial solid waste resource utilization and green agricultural development. Summary of the Invention

[0005] This application provides a non-fired soilless cultivation pebble for ecological agriculture and its preparation method, in order to solve the problems in the existing technology that soilless cultivation substrates are difficult to balance physical properties, production costs and environmental protection requirements, as well as the resource waste and environmental pollution caused by the low-value stockpiling of solid waste from the gold industry, and the lack of an effective technical path to combine the two and realize the high-value and targeted transformation of solid waste into high-performance cultivation substrates.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides a soilless cultivation pebble for non-fired ecological agriculture, such as... Figure 1 As shown, the soilless cultivation pebbles are composed of the following parts by weight: core solid waste powder: 70–85 parts; gold smelting desulfurization gypsum: 2–10 parts; red mud: 0–10 parts; water: 5–15 parts; wherein, the core solid waste powder is composed of 60–80 parts of gold tailings, 10–20 parts of fly ash and 10–20 parts of slag powder.

[0007] Preferably, the gold tailings contain ≥65% potassium-sodium feldspar by mass, with a particle size ≤0.15mm and a specific surface area of ​​100–450m². 3 / kg.

[0008] Preferably, the fly ash is Class III or higher raw ash emitted by the power plant.

[0009] Preferably, the gold smelting desulfurization gypsum is a byproduct of gold smelting flue gas desulfurization.

[0010] Preferably, the mass percentage of calcium sulfate dihydrate in the gold smelting desulfurization gypsum is not less than 80%.

[0011] Preferably, the particle size of the gold smelting desulfurization gypsum is ≤0.1mm, and the particle size of the red mud is ≤0.1mm.

[0012] This invention also provides a method for preparing soilless cultivation pebbles for non-fired ecological agriculture, characterized by comprising the following steps: (1) Mix gold tailings, fly ash and slag powder in proportion and stir for 2–5 minutes at 15–30℃ and 25–40r / min to obtain core solid waste powder. (2) Add gold smelting desulfurization gypsum to the core solid waste powder. If red mud is to be added, add it at the same time. Continue stirring for 1–3 minutes at 15–30℃ and 25–40 r / min to obtain a mixture. (3) Add water to the mixture and stir for 2.5–5.5 minutes at 20–30°C and 30–45 r / min to obtain a plastic mixture; (4) The plastic mixture is fed into a roller mill and extruded and shaped under an extrusion pressure of 1.5–3 MPa and a roller speed of 5–10 r / min. The mixture is then screened to obtain semi-finished granules. The unshaped material under the screen is returned to step (2) or (3) for reuse. (5) The semi-finished particles are fed into a pelletizing machine and rolled for 10–20 minutes at a drum speed of 15–25 r / min and an inclination angle of 30°–45° to perform precision forming; (6) The refined granules are left to stand and cure in an environment of 17–32℃ and 40%–60% relative humidity for 3–8 hours to obtain the finished pebbles.

[0013] Preferably, the sieve used for screening in step (4) has a mesh size of 2cm, 3cm or 5cm, wherein a mesh size of 2cm is used for leafy vegetable cultivation, a mesh size of 3cm is used for fruit vegetable cultivation, and a mesh size of 5cm is used for flower cultivation.

[0014] Preferably, the recycling rate of unformed materials in step (4) does not exceed 30% of the total material mass.

[0015] This invention also provides an application of non-fired ecological agricultural soilless cultivation pebbles in the soilless cultivation of vegetables or flowers.

[0016] The beneficial effects achieved by using the present invention described above are as follows: 1. This invention uses bulk industrial solid waste such as gold tailings, gold smelting desulfurization gypsum, fly ash, and slag powder as core raw materials. Through precise proportioning, it achieves the synergistic treatment of multiple solid wastes. In particular, by organically combining gold tailings and gold smelting desulfurization gypsum, two solid wastes from the same source, each ton of finished product can dispose of 0.75-0.9 tons of solid waste from the gold industry, with a total material utilization rate of over 95%. This not only significantly reduces the environmental risks caused by solid waste stockpiling but also transforms the "environmental burden" into "agricultural resources," providing a practical and feasible path for the green and circular development of the gold industry. 2. In this application, the active silica-alumina components in slag powder and fly ash undergo a synergistic cementation reaction under alkaline conditions to form a gel network of hydrated calcium silicate (CSH), which firmly binds the solid waste particles. This network structure simultaneously encapsulates and fixes the potassium and sodium feldspar components in gold tailings and the calcium and sulfur components in desulfurized gypsum. During cultivation, water penetration causes the gel network to slowly hydrate and dissolve, and through ion exchange, it continuously releases potassium at a controllable rate (potassium: 0.5-2 mg / (kg·d); calcium: 0.8-2.2 mg / (kg·d)). + Na + Ca 2+ SO4 2- It contains essential plant nutrients such as ions, realizing the function of the substrate as a fertilizer source, which can reduce the amount of chemical fertilizer used during the growing season by 30%-50%. 3. This invention employs a room-temperature, non-firing process of "roller extrusion preforming + ball rolling precision forming". Roller extrusion, under a pressure of 1.5-3 MPa, forces the material to pack tightly and initially form internal microporous channels; subsequent ball rolling densifies and rounds the particle surface, forming an "eggshell" structure with an outer covering and a loose interior. The final product, pea gravel, has a rich porous structure, possessing suitable bulk density, excellent water absorption, and high air permeability. This effectively balances the supply of moisture and air, creating an optimal growth environment for crop roots and avoiding the compaction problem of traditional organic substrates and the excessive air permeability problem of single inorganic substrates. 4. This invention utilizes a completely non-fired, room-temperature process, eliminating the high-temperature calcination required by traditional ceramsite. Energy consumption per ton of finished product is ≤50 kWh, a reduction of over 90% compared to sintered ceramsite, resulting in a significant reduction in carbon emissions. Raw materials are almost entirely derived from inexpensive industrial solid waste, and waste is further reduced through a material recycling system, making the raw material cost per ton of finished product 40%-60% lower than that of commercial mixed substrates, achieving a high degree of balance between environmental and economic benefits. 5. This invention, by adjusting the aperture of the roller mold, can precisely produce pea gravel products with different particle sizes, such as 2cm (leafy vegetables), 3cm (fruit vegetables), and 5cm (flowers), to meet the growth space requirements of different crop root systems. This pea gravel can be used alone or mixed with a small amount of organic substrate (such as ≤20% coconut coir), suitable for various soilless cultivation methods such as hydroponics and substrate culture. It is widely used in the cultivation of crops such as lettuce, tomatoes, cucumbers, roses, and large green plants, demonstrating high survival rates, robust growth, and excellent quality.

[0017] This solves the problems of existing soilless cultivation substrates, which are difficult to balance physical properties, production costs, and environmental protection requirements, as well as the resource waste and environmental pollution caused by the low-value stockpiling of solid waste from the gold industry, and the lack of an effective technical path to combine the two and realize the high-value and targeted transformation of solid waste into high-performance cultivation substrates. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the synthetic structure of soilless cultivation pebbles for non-fired ecological agriculture provided in an embodiment of the present invention. Detailed Implementation

[0019] The technical solution of the present invention is illustrated below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0020] To better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. While exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0021] The following description, with reference to the accompanying drawings, illustrates an embodiment of this application of soilless cultivation pebbles for non-fired ecological agriculture and its preparation method. Addressing the long-standing issues of high energy consumption and limited functionality of soilless cultivation substrates, coupled with the pollution caused by the low-value storage of gold solid waste, this application provides a method for soilless cultivation pebbles for non-fired ecological agriculture. In this method, bulk industrial solid wastes such as gold tailings, gold smelting desulfurization gypsum, fly ash, and slag powder are used as core raw materials. Precise proportioning achieves the synergistic treatment of multiple solid wastes. The synergistic gelation reaction between slag powder and the active silica-alumina components in fly ash forms a gel network, achieving both material bonding and controllable release of essential plant nutrients during cultivation. Nutrient ions reduce fertilizer usage; a room-temperature, non-fired process of "roller extrusion preforming + ball rolling precision forming" is used to prepare pea stones with a porous interior and a dense exterior, achieving both excellent water absorption and air permeability while avoiding the defects of traditional substrates; and products with different particle sizes of 2-5cm can be prepared by adjusting the mold pore size, suitable for hydroponics, substrate culture and other modes and various crops. At the same time, the raw material cost is reduced by 40%-60% compared to commercial mixed substrates, ultimately solving the dual problems of soilless cultivation substrates and solid waste treatment in the gold industry in existing technologies, achieving a balance between environmental and economic benefits.

[0022] The present invention will be further described in conjunction with the following embodiments.

[0023] Example 1 This invention provides a soilless cultivation pebble for non-fired ecological agriculture. The soilless cultivation pebble is composed of the following parts by weight: core solid waste powder: 70 parts; gold smelting desulfurization gypsum: 2 parts; red mud: 1 part; water: 5 parts; wherein, the core solid waste powder is composed of 60 parts of gold tailings, 10 parts of fly ash and 10 parts of slag powder.

[0024] Among them, the mass ratio of potassium and sodium feldspar in gold tailings is ≥65%, the particle size is ≤0.15mm, and the specific surface area is 100–450m². 3 / kg.

[0025] Fly ash refers to the raw ash of grade III or above emitted by power plants.

[0026] Among them, gold smelting desulfurization gypsum is a by-product of gold smelting flue gas desulfurization.

[0027] Among them, the mass ratio of calcium sulfate dihydrate in desulfurization gypsum for gold smelting shall not be less than 80%.

[0028] Among them, the particle size of desulfurized gypsum for gold smelting is ≤0.1mm, and the particle size of red mud is ≤0.1mm.

[0029] This invention also provides a method for preparing soilless cultivation pebbles for non-fired ecological agriculture, characterized by comprising the following steps: (1) Mix gold tailings, fly ash and slag powder in proportion and stir for 5 minutes at 30℃ and 40r / min to obtain core solid waste powder; (2) Add gold smelting desulfurization gypsum to the core solid waste powder. If red mud is to be added, add it at the same time. Continue stirring for 3 minutes at 30℃ and 40r / min to obtain the mixture. (3) Add water to the mixture and stir for 5 minutes at 30°C and 45 r / min to obtain a plastic mixture; (4) The plastic mixture is fed into the roller mill and extruded into shape under an extrusion pressure of 3MPa and a roller speed of 10r / min. The semi-finished granules are then obtained by screening. The unformed material under the screen is returned to step (2) or (3) for reuse. (5) The semi-finished pellets are fed into the pelletizing machine and rolled for 20 minutes at a drum speed of 25 r / min and an inclination angle of 45° to perform precision forming; (6) The refined granules are left to stand for 8 hours in an environment of 30°C and 40% relative humidity to obtain the finished pebbles.

[0030] In step (4), the sieve used for screening has a mesh size of 2cm, which is used for leafy vegetable cultivation.

[0031] In step (4), the recycling rate of unformed materials shall not exceed 30% of the total material mass.

[0032] This invention also provides an application of non-fired ecological agricultural soilless cultivation pebbles in the soilless cultivation of vegetables or flowers.

[0033] Specifically, the performance and application effects of using pebbles in leafy vegetable (lettuce) cultivation are as follows: Physical properties: Particle size 2.0±0.2cm, bulk density 1050kg / m³ 3 It has a water absorption rate of 15% and an air permeability of 16%.

[0034] Nutrient release: Potassium release rate 1.2 mg / (kg·d), calcium release rate 1.5 mg / (kg·d).

[0035] Cultivation trial (lettuce, 28 days): With only one application of nitrogen fertilizer, the survival rate was 98%, the fresh weight of a single plant increased by 12% compared to the traditional perlite substrate, the root system was well-developed, and there was no compaction.

[0036] Example 2 This invention provides a soilless cultivation pebble for non-fired ecological agriculture. The soilless cultivation pebble is composed of the following parts by weight: core solid waste powder: 78 parts; gold smelting desulfurization gypsum: 6 parts; red mud: 6 parts; water: 10 parts; wherein, the core solid waste powder is composed of 70 parts of gold tailings, 15 parts of fly ash and 15 parts of slag powder.

[0037] Among them, the mass ratio of potassium and sodium feldspar in gold tailings is ≥65%, the particle size is ≤0.15mm, and the specific surface area is 100–450m². 3 / kg.

[0038] Fly ash refers to the raw ash of grade III or above emitted by power plants.

[0039] Among them, gold smelting desulfurization gypsum is a by-product of gold smelting flue gas desulfurization.

[0040] Among them, the mass ratio of calcium sulfate dihydrate in desulfurization gypsum for gold smelting shall not be less than 80%.

[0041] Among them, the particle size of desulfurized gypsum for gold smelting is ≤0.1mm, and the particle size of red mud is ≤0.1mm.

[0042] This invention also provides a method for preparing soilless cultivation pebbles for non-fired ecological agriculture, characterized by comprising the following steps: (1) Mix gold tailings, fly ash and slag powder in proportion and stir for 5 minutes at 30℃ and 40r / min to obtain core solid waste powder; (2) Add gold smelting desulfurization gypsum to the core solid waste powder. If red mud is to be added, add it at the same time. Continue stirring for 3 minutes at 30℃ and 40r / min to obtain the mixture. (3) Add water to the mixture and stir for 5 minutes at 30°C and 45 r / min to obtain a plastic mixture; (4) The plastic mixture is fed into the roller mill and extruded into shape under an extrusion pressure of 3MPa and a roller speed of 10r / min. The semi-finished granules are then obtained by screening. The unformed material under the screen is returned to step (2) or (3) for reuse. (5) The semi-finished pellets are fed into the pelletizing machine and rolled for 20 minutes at a drum speed of 25 r / min and an inclination angle of 45° to perform precision forming; (6) The refined granules are left to stand for 8 hours in an environment of 32℃ and 60% relative humidity to obtain the finished pebbles.

[0043] In step (4), the sieve used for screening has a mesh size of 3cm, which is used for fruit and vegetable cultivation.

[0044] In step (4), the recycling rate of unformed materials shall not exceed 30% of the total material mass.

[0045] This invention also provides an application of non-fired ecological agricultural soilless cultivation pebbles in the soilless cultivation of vegetables or flowers.

[0046] Specifically, the performance and application effects of using pebbles in fruit and vegetable (tomato) cultivation are as follows: Physical properties: Particle size 3.0±0.3cm, bulk density 1080kg / m³ 3 Water absorption rate: 13%.

[0047] Nutrient release: Potassium release rate 1.5 mg / (kg·d), calcium release rate 1.8 mg / (kg·d).

[0048] Cultivation experiment (tomato): The fruiting period was extended by 7 days, the weight of a single fruit increased by 8% compared with the traditional expanded clay substrate, and no root rot caused by oxygen deficiency occurred throughout the entire growth period.

[0049] Example 3 This invention provides a soilless cultivation pebble for non-fired ecological agriculture. The soilless cultivation pebble is composed of the following parts by weight: core solid waste powder: 85 parts; gold smelting desulfurization gypsum: 10 parts; red mud: 10 parts; water: 15 parts; wherein, the core solid waste powder is composed of 80 parts of gold tailings, 20 parts of fly ash and 20 parts of slag powder.

[0050] Among them, the mass ratio of potassium and sodium feldspar in gold tailings is ≥65%, the particle size is ≤0.15mm, and the specific surface area is 100–450m². 3 / kg.

[0051] Fly ash refers to the raw ash of grade III or above emitted by power plants.

[0052] Among them, gold smelting desulfurization gypsum is a by-product of gold smelting flue gas desulfurization.

[0053] Among them, the mass ratio of calcium sulfate dihydrate in desulfurization gypsum for gold smelting shall not be less than 80%.

[0054] Among them, the particle size of desulfurized gypsum for gold smelting is ≤0.1mm, and the particle size of red mud is ≤0.1mm.

[0055] This invention also provides a method for preparing soilless cultivation pebbles for non-fired ecological agriculture, characterized by comprising the following steps: (1) Mix gold tailings, fly ash and slag powder in proportion and stir for 5 minutes at 30℃ and 40r / min to obtain core solid waste powder; (2) Add gold smelting desulfurization gypsum to the core solid waste powder. If red mud is to be added, add it at the same time. Continue stirring for 3 minutes at 30℃ and 40r / min to obtain the mixture. (3) Add water to the mixture and stir for 5.5 minutes at 30°C and 45 r / min to obtain a plastic mixture; (4) The plastic mixture is fed into the roller mill and extruded into shape under an extrusion pressure of 3MPa and a roller speed of 10r / min. The semi-finished granules are then obtained by screening. The unformed material under the screen is returned to step (2) or (3) for reuse. (5) The semi-finished pellets are fed into the pelletizing machine and rolled for 20 minutes at a drum speed of 25 r / min and an inclination angle of 45° to perform precision forming; (6) The refined granules are left to stand for 8 hours in an environment of 32℃ and 60% relative humidity to obtain the finished pebbles.

[0056] In step (4), the sieve used for screening has a mesh size of 5cm, which is used for flower cultivation.

[0057] In step (4), the recycling rate of unformed materials shall not exceed 30% of the total material mass.

[0058] This invention also provides an application of non-fired ecological agricultural soilless cultivation pebbles in the soilless cultivation of vegetables or flowers.

[0059] Specifically, the performance and application effects of using pebbles for cultivating flowers (Monstera deliciosa) are as follows: Physical properties: Particle size 5.0±0.4cm, bulk density 1020kg / m³ 3 It has a water absorption rate of 12% and a breathability of 18%.

[0060] Nutrient release: Calcium release rate 1.1 mg / (kg·d).

[0061] Cultivation experiment (Monstera deliciosa): Watering interval can be extended to 15 days, root system spread is significantly better than traditional sandy substrate, new leaves sprout 2 more, and growth is vigorous.

[0062] Comparative Example 1 A traditional sintered ceramsite is made by mixing 60 parts clay, 20 parts fly ash, and 20 parts water, granulating the mixture, and then calcining it at 1100℃ for 2 hours to obtain ceramsite with a particle size of 3cm.

[0063] Specifically, the performance of traditional sintered ceramsite was tested, and the performance test results and application effects are as follows: Physical properties: Particle size 3.0±1.0cm (large deviation), bulk density 1200kg / m³ 3 It has a water absorption rate of 8% and no nutrient release function.

[0064] Cultivation experiment (tomato): required additional application of NPK compound fertilizer 3 times, short fruiting period, and single fruit weight 8% lower than in Example 2.

[0065] Energy consumption and cost: The energy consumption per ton of product is approximately 600 kWh, the raw material cost is 2.5 times that of Example 2, and there is no solid waste utilization benefit.

[0066] Comparative Example 2 A soilless cultivation pebbles for non-fired ecological agriculture, wherein, based on the formula of Example 1, 5 parts of desulfurized gypsum are removed, and the remaining amount is made up by an equal amount of gold tailings, and the preparation process is the same as in Example 1.

[0067] Specifically, the performance testing of soilless cultivation pebbles without desulfurized gypsum was conducted as follows: Molding performance: The particles have poor strength during the molding process, resulting in a high breakage rate in the pelletizing machine and a final yield of less than 60%.

[0068] Product performance: The pebbles have a loose structure and are easily broken in water, with no release of calcium or sulfur elements.

[0069] Application results: When cultivating lettuce, obvious symptoms of calcium deficiency (scorched edges of new leaves) appeared, and the growth was far inferior to that in Example 1.

[0070] Comparative Example 3 A non-fired ecological agricultural soilless cultivation pebbles, wherein the preparation method skips the roller extrusion step (step 4), and the plastic mixture is directly fed into the pelletizing machine for molding, with the same formula as in Example 1.

[0071] Specifically, the performance of soilless cultivation pebbles formed by a single pelletizing machine was tested as follows: Physical properties: The particle size distribution is extremely uneven (ranging from 1 to 5 cm), with poor sphericity, large differences in bulk density, and uneven air permeability.

[0072] Application results: When used in lettuce cultivation, the imbalance between water retention and air permeability led to waterlogging in some areas causing root rot, while other areas suffered from drought, resulting in an overall survival rate of only 85%.

[0073] In summary, Examples 1-3 demonstrate that the synergistic combination of gold tailings and gold smelting desulfurization gypsum is key to achieving stable pea gravel formation and slow-release nutrient function. Comparative Example 2, lacking a core cementing component and calcium source, resulted in low forming rate, structural collapse, and calcium deficiency in crops, confirming the necessity of their synergistic effect. The composite process of "roller extrusion pre-forming + ball rolling precision forming" successfully constructed an eggshell structure with a dense outer layer and a loose inner layer, giving the pea gravel both high air permeability and suitable water absorption. Comparative Example 3, lacking a pre-compaction step, resulted in dispersed particle size distribution and an imbalance between air permeability and water retention, proving the decisive role of the composite process in performance regulation. The pea gravel of this invention significantly outperforms traditional sintered ceramsite in both physicochemical properties and agricultural effects. Its unique ion-exchange nutrient release mechanism realizes that the substrate is also a fertilizer source, reducing fertilizer application by 30-50%. The entire process of no-firing reduces energy consumption to ≤50 kWh / t, saving more than 90% energy compared to sintered ceramsite. With solid waste accounting for ≥75% of the raw materials, the driving cost is reduced by 40-60%.

[0074] This application provides a non-fired soilless cultivation pebble for ecological agriculture, using bulk industrial solid waste such as gold tailings, gold smelting desulfurization gypsum, fly ash, and slag powder as core raw materials. Through precise proportioning, it achieves the synergistic treatment of multiple solid wastes. Utilizing the synergistic gelation reaction of the active silica-alumina components in the slag powder and fly ash to form a gel network, it not only achieves material bonding and shaping but also allows for the controlled release of essential plant nutrient ions during cultivation, reducing fertilizer usage. Employing a room-temperature non-fired process of "roller extrusion pre-forming + ball rolling precision forming," it produces a porous internal and dense external "eggshell" structure pebble, balancing excellent water absorption and air permeability, avoiding the defects of traditional substrates. Furthermore, by adjusting the mold pore size, it can produce products with different particle sizes of 2-5 cm, suitable for hydroponics, substrate cultivation, and various crops. Simultaneously, the raw material cost is reduced by 40%-60% compared to commercial mixed substrates, ultimately solving the dual problems of soilless cultivation substrates and gold industry solid waste treatment in existing technologies, achieving a balance between environmental and economic benefits.

[0075] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A type of non-fired ecological agricultural soilless cultivation pebble, characterized in that, The soilless cultivation pebbles are composed of the following parts by weight: Core solid waste powder: 70–85 parts; Gold smelting desulfurization gypsum: 2–10 parts; Red mud: 0–10 parts; Water: 5–15 parts; The core solid waste powder consists of 60–80 parts gold tailings, 10–20 parts fly ash, and 10–20 parts slag powder.

2. The soilless cultivation pebbles for non-fired ecological agriculture according to claim 1, characterized in that, The gold tailings contain ≥65% potassium-sodium feldspar by mass, with a particle size ≤0.15mm and a specific surface area of ​​100–450m². 3 / kg.

3. The soilless cultivation pebbles for non-fired ecological agriculture according to claim 1, characterized in that, The fly ash mentioned is the raw ash of grade III or above emitted by the power plant.

4. The soilless cultivation pebbles for non-fired ecological agriculture according to claim 1, characterized in that, The gold smelting desulfurization gypsum is a byproduct of gold smelting flue gas desulfurization.

5. The soilless cultivation pebbles for non-fired ecological agriculture according to claim 1, characterized in that, The mass percentage of calcium sulfate dihydrate in the gold smelting desulfurization gypsum shall not be less than 80%.

6. The soilless cultivation pebbles for non-fired ecological agriculture according to claim 1, characterized in that, The particle size of the gold smelting desulfurization gypsum is ≤0.1mm, and the particle size of the red mud is ≤0.1mm.

7. A method for preparing soilless cultivation pebbles for non-fired ecological agriculture based on any one of claims 1-6, characterized in that, Includes the following steps: (1) Mix gold tailings, fly ash and slag powder in proportion and stir for 2–5 minutes at 15–30℃ and 25–40r / min to obtain core solid waste powder. (2) Add gold smelting desulfurization gypsum to the core solid waste powder. If red mud is to be added, add it at the same time. Continue stirring for 1–3 minutes at 15–30℃ and 25–40 r / min to obtain a mixture. (3) Add water to the mixture and stir for 2.5–5.5 minutes at 20–30°C and 30–45 r / min to obtain a plastic mixture; (4) The plastic mixture is fed into a roller mill and extruded and shaped under an extrusion pressure of 1.5–3 MPa and a roller speed of 5–10 r / min. The mixture is then screened to obtain semi-finished granules. The unshaped material under the screen is returned to step (2) or (3) for reuse. (5) The semi-finished particles are fed into a pelletizing machine and rolled for 10–20 minutes at a drum speed of 15–25 r / min and an inclination angle of 30°–45° to perform precision forming; (6) The refined granules are left to stand and cure in an environment of 17–32℃ and 40%–60% relative humidity for 3–8 hours to obtain the finished pebbles.

8. The method for preparing soilless cultivation pebbles for non-fired ecological agriculture according to claim 7, characterized in that, In step (4), the mesh size of the sieve used for sieving is 2cm, 3cm or 5cm. Among them, the mesh size of 2cm is used for leafy vegetable cultivation, the mesh size of 3cm is used for fruit vegetable cultivation, and the mesh size of 5cm is used for flower cultivation.

9. The method for preparing soilless cultivation pebbles for non-fired ecological agriculture according to claim 7, characterized in that, In step (4), the recycling rate of unformed materials shall not exceed 30% of the total material mass.

10. The application of non-fired ecological agricultural soilless cultivation pebbles as described in any one of claims 1-6 in soilless cultivation of vegetables or flowers.

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