Device for preparing plant growth substrate from phosphogypsum

Abstract

The utility model relates to a kind of phosphogypsum preparation plant growth matrix devices, belong to phosphogypsum resource utilization technical field. Mainly including raw material pretreatment system, organic matter composite system, matrix proportion mixing system, physical performance control system and biological activity improvement system;Raw material pretreatment system includes phosphogypsum storage bin, heavy metal remover, fluoride purification device and pH regulator connected in sequence, heavy metal remover is internally provided with multistage reaction chamber, each multistage reaction chamber is equipped with pH sensor and heavy metal ion concentration detector;Fluoride purification device is internally provided with ultrasonic generator and lime milk circulation spraying system;Organic matter composite system includes organic material bin, fermentation composting device, composting degree detector and nutrient element adder, adjustable height ventilation duct is arranged in fermentation composting device, ventilation duct is connected with the composting degree detector by control system.

Description

Technical Field

[0001] This utility model belongs to the field of phosphogypsum resource utilization technology, specifically relating to a device for preparing plant growth substrate from phosphogypsum. Background Technology

[0002] As a byproduct of phosphate fertilizer production, phosphogypsum has long been difficult to utilize effectively due to its presence of harmful substances such as heavy metals and fluorides, as well as its strong acidity. Its accumulation has occupied land and posed a potential pollution risk to the environment.

[0003] Phosphogypsum contains abundant plant nutrients such as calcium and sulfur, and has potential resource value in the preparation of plant growth substrates. However, its application faces two major technical challenges: first, the removal efficiency of heavy metals and fluorides in phosphogypsum is low, which can easily lead to the toxicity of the substrate to plant growth; second, the physical properties and biological activity of phosphogypsum substrates are difficult to precisely control, making it difficult to meet the diverse requirements of different plants for substrate porosity, permeability, and nutrients. These problems limit the large-scale application of phosphogypsum in the field of plant growth substrates. There is an urgent need to develop an efficient and systematic preparation technology to achieve the harmless treatment and resource utilization of phosphogypsum, while ensuring that the physical properties and biological activity of the substrate can meet the complex needs of plant growth, thus providing high-quality substrate materials for agricultural production. Utility Model Content

[0004] To overcome the problems in the prior art, such as the low removal efficiency of heavy metals and fluorides in phosphogypsum, which easily leads to the toxic effects of the substrate on plant growth, and the difficulty in precisely controlling the physical properties and biological activity of phosphogypsum substrates to meet the diverse requirements of different plants for substrate porosity, air permeability and nutrition, this utility model provides a device for preparing plant growth substrates using phosphogypsum, thereby overcoming the shortcomings of the prior art.

[0005] To achieve the above objectives, this utility model is implemented through the following technical solution: A device for preparing plant growth substrate from phosphogypsum mainly includes a raw material pretreatment system, an organic matter composite system, a substrate proportioning and mixing system, a physical property control system, and a bioactivity improvement system; the raw material pretreatment system includes a phosphogypsum storage silo, a heavy metal remover, a fluoride purification device, and a pH regulator connected in sequence. The heavy metal remover has multiple reaction chambers inside, each equipped with a pH sensor and a heavy metal ion concentration detector; the fluoride purification device has an ultrasonic generator and a lime milk circulating spray system inside; the organic matter composite system includes an organic material silo, a fermentation and composting device, a composting degree detector, and a nutrient element additive connected in sequence. The fermentation and composting device has an adjustable-height ventilation duct inside, and the ventilation duct is connected to the composting degree detector via a control... The system comprises the following components: an automatic batching machine, a biaxial mixer, and a water-retaining agent additive and a microbial inoculum, all connected in sequence to the matrix mixing system; a pH adjuster and a nutrient element additive, both connected to the automatic batching machine; adjustable-angle blades of the biaxial mixer connected to the drive shaft via an angle adjustment mechanism; a porosity adjustment device, an air permeability meter, a bulk density controller, and a particle size classifier connected in sequence; a porosity adjustment device connected to the biaxial mixer and equipped with a vibrating sieve module; and a bioactivity improvement system consisting of a microbial fermentation tank, an enzyme additive, a growth regulator mixer, and a trace element chelator connected in sequence; a trace element chelator connected to the porosity adjustment device; and a temperature control system and an automatic pH adjustment system installed inside the microbial fermentation tank.

[0006] Furthermore, the multi-stage reaction chambers are a three-stage series structure. The first-stage reaction chamber is equipped with a sodium sulfide inlet, the second-stage reaction chamber is equipped with a sodium hydroxide inlet, and the third-stage reaction chamber is equipped with a flocculant inlet. The detection data from the pH sensor and the heavy metal ion concentration detector are connected to the central control system via a data transmission line. The central control system automatically adjusts the dosage of chemical reagents and the reaction time in each stage of the reaction chamber based on the detection data. Each reaction chamber is equipped with a precipitate discharge port at the bottom, which is controlled to open and close by an electric valve.

[0007] Furthermore, the lime slurry circulating spray system includes a storage tank, a circulating pump, and multi-layer spray heads. The multi-layer spray heads are distributed along the height direction of the fluoride purification device, and the spray angle of the spray heads can be adjusted within the range of 30°-90°. The ultrasonic generator works synchronously with the lime slurry circulating spray system, and enhances the reaction contact area between lime slurry and fluoride in phosphogypsum through the ultrasonic cavitation effect.

[0008] Furthermore, the ventilation duct includes a main ventilation duct and branch ventilation ducts. The branch ventilation ducts are connected to the main ventilation duct and driven by a lifting mechanism. The lifting mechanism can adjust the vertical position of the branch ventilation ducts within the fermentation and composting device.

[0009] Furthermore, the main ventilation duct is installed at the top of the fermentation and composting unit, with its inlet end connected to an external air supply system; the branch ventilation ducts are vertically installed inside the fermentation and composting unit and arranged circumferentially along the inner wall, with their top ends passing through a sliding seal at the top of the fermentation and composting unit and connected to the outlet of the main ventilation duct via a flexible connecting hose; air outlet holes are evenly opened on the bottom side wall of the branch ventilation ducts, and their bottom ends are designed with a tapered structure; the lifting mechanism includes a servo motor, a ball screw, a screw nut seat, and a guide rod; the ball screw is vertically fixed inside the fermentation and composting unit via a bearing seat; the servo motor is fixed to a bracket at the top of the fermentation and composting unit, and its output shaft is connected to the top of the ball screw via a coupling; the screw nut seat is threadedly connected to the ball screw; the guide rod is vertically fixed to a bracket on the outer wall of the fermentation and composting unit; the screw nut seat is slidably installed on the guide rod and fixedly connected to the top of the branch ventilation duct via a connecting flange.

[0010] Furthermore, the vibrating screening module includes a vibrating motor, an eccentric block, and a multi-layer screen. The vibration frequency of the vibrating motor can be adjusted within the range of 10-50Hz. The mesh size of the multi-layer screen decreases sequentially from top to bottom, namely 10mm, 5mm, 2mm, and 1mm. By vibrating at different frequencies, the matrix particles are reorganized into layers according to their particle size. The vibrating screening module is connected to an online porosity detection device, which automatically adjusts the vibration parameters based on the porosity detection results.

[0011] The beneficial effects of this utility model are: This invention solves the technical problems of high levels of heavy metals and fluorides in phosphogypsum and poor physicochemical properties of the substrate through the synergistic effect of five systems: raw material pretreatment, organic matter compounding, substrate proportioning and mixing, physical property regulation, and bioactivity improvement. In the raw material pretreatment, a multi-stage reaction chamber combined with a pH sensor and a heavy metal ion concentration detector precisely removes heavy metals, while an ultrasonic generator and a lime slurry circulating spray system work together to enhance fluoride purification efficiency. The organic matter compounding system optimizes the fermentation process through adjustable-height ventilation ducts and a decomposition degree detector, ensuring thorough decomposition of organic matter. The substrate proportioning and mixing system achieves precise proportioning using adjustable-angle stirring blades and an automatic batching machine. The physical property regulation system dynamically adjusts porosity and particle size through a vibrating sieve module, and the bioactivity improvement system enhances substrate activity through microbial fermentation and trace element chelation. Ultimately, this achieves efficient conversion of phosphogypsum, producing a safe, fertile plant growth substrate with superior physical properties, significantly improving its agricultural application value. Attached Figure Description

[0012] Figure 1 This is a three-dimensional schematic diagram of the fermentation and composting device of this utility model.

[0013] Figure 2 This is a schematic diagram of the internal structure of the fermentation and composting device of this utility model.

[0014] Figure 3 This is a schematic diagram of the preparation process of this utility model.

[0015] In the attached diagram: 1. Phosphogypsum storage silo; 2. Heavy metal remover; 3. Fluoride purification device; 4. pH regulator; 5. Organic material silo; 6. Fermentation and composting device; 7. Composting degree detector; 8. Nutrient element adder; 9. Automatic batching machine; 10. Twin-shaft mixer; 11. Water-retaining agent adder; 12. Microbial inoculant; 13. Porosity adjustment device; 14. Air permeability meter; 15. Bulk density controller; 16. Particle size classifier; 17. Microbial agent fermentation tank; 18. Enzyme preparation adder; 19. Growth regulator mixer; 20. Trace element chelator; 21. Heavy metal ion concentration detector; 22. pH sensor; 31. Ultrasonic generator; 32. Lime slurry circulating spray system; 61. Main ventilation duct; 62. Branch ventilation duct; 63. Servo motor; 64. Ball screw; 65. Screw nut seat; 66. Guide rod; 131. Vibrating screen module. Detailed Implementation

[0016] To make the objectives, technical solutions, and beneficial effects of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, so as to facilitate the understanding of those skilled in the art.

[0017] This utility model discloses a device for preparing plant growth substrates from phosphogypsum. The device mainly includes a raw material pretreatment system, an organic matter composite system, a substrate ratio mixing system, a physical property regulation system, and a bioactivity improvement system. The raw material pretreatment system includes a phosphogypsum storage silo 1, a heavy metal remover 2, a fluoride purification device 3, and a pH adjuster 4 connected in sequence; the organic matter composite system includes an organic material silo 5, a fermentation and composting device 6, a composting degree detector 7, and a nutrient element adder 8 connected in sequence; the matrix proportioning and mixing system includes an automatic batching machine 9, a twin-shaft mixer 10 connected in sequence, and a water-retaining agent adder 11 and a microbial inoculum 12 connected to the twin-shaft mixer 10 respectively; the physical property control system includes a porosity adjustment device 13, an air permeability tester 14, a bulk density controller 15, and a particle size classifier 16 connected in sequence, with the porosity adjustment device 13 connected to the twin-shaft mixer 10; the bioactivity improvement system includes a microbial agent fermentation tank 17, an enzyme preparation adder 18, a growth regulator mixer 19, and a trace element chelator 20 connected in sequence, with the trace element chelator 20 connected to the porosity adjustment device 13. Each system is connected via pipelines, conveyor belts, and a central control system. The central control system includes a main control PLC, which receives pH / ion data from the heavy metal remover 2 and C / N ratio data from the decay maturity detector 7. It transmits commands to the vibration module of the porosity adjustment device 13 and the ventilation duct lifting mechanism via an RS485 bus to achieve data synchronization. When the material flows through the conveyor belt, the control system coordinates the opening and closing sequence of the valves to form a complete process from raw material input to finished product output, ensuring the intelligent purification, compounding, and improvement of phosphogypsum.

[0018] The raw material pretreatment system is located at the beginning of the device. The phosphogypsum storage silo 1 is a cylindrical structure with an inlet at the top connected to the phosphogypsum supply system, and a screw conveyor at the bottom connected to the heavy metal remover 2. The heavy metal remover 2 is connected to the fluoride purification device 3 via a pipeline. The fluoride purification device 3 is connected to the pH regulator 4 via a pumping system. The output of the pH regulator 4 is connected to the automatic batching machine 9 of the matrix proportioning and mixing system. This sequential connection ensures that the material is purified step by step, avoiding the residue of harmful substances and improving the safety of the matrix. The heavy metal remover 2 has a multi-stage reaction chamber, which is a three-stage series structure. The first-stage reaction chamber has a sodium sulfide dosing port, the second-stage reaction chamber has a sodium hydroxide dosing port, and the third-stage reaction chamber has a flocculant dosing port. By adding sodium sulfide or sodium hydroxide solution, the heavy metal ions such as cadmium and lead in the phosphogypsum react to form insoluble precipitates. Each multi-stage reaction chamber is equipped with a pH sensor 22 and a heavy metal ion concentration detector 21. The detection data from the pH sensor 22 and the heavy metal ion concentration detector 21 are connected to the central control system via a data transmission line. The central control system automatically adjusts the dosage of chemical reagents and the reaction time in each reaction chamber based on the detection data. For example, when the pH sensor reading is below 6.5 or above 8.5, the sodium hydroxide dosage is increased by 10%; when the heavy metal ion concentration detector reading exceeds 50 ppm, the reaction time is extended by 20%. The control algorithm uses PID regulation, and the setpoint is based on a preset threshold (pH 7.0 ± 0.5, heavy metal < 10 ppm). Each reaction chamber has a precipitate discharge port at the bottom, which is controlled by an electric valve. This multi-stage structure achieves a heavy metal removal rate of over 98% through step-by-step precipitation reactions, ensuring matrix safety. During operation, the heavy metal remover 2 receives phosphogypsum material from the phosphogypsum storage silo 1. First, sodium sulfide is added in the first-stage reaction chamber to form preliminary precipitate. Then, the material flows to the second stage where sodium hydroxide is added to enhance alkaline precipitation. In the third stage, a flocculant is added to accelerate sedimentation. A pH sensor 22 monitors the pH value in real time, ensuring it remains within the range of 4-9. A heavy metal ion concentration detector 21 automatically activates the next stage of flow when the ion concentration falls below a threshold. This intelligent control mechanism ensures efficient reaction, avoids excessive reagent waste, and periodically discharges sediment through the precipitate discharge port, improving the continuous operation capability of the device. Through multi-stage reaction and real-time monitoring, the heavy metal remover 2 significantly reduces the content of harmful heavy metals in phosphogypsum, ensuring that the subsequent substrate is non-toxic to plants. Simultaneously, intelligent control reduces manual intervention and improves the automation level of the device.

[0019] As one possible implementation, the multi-stage reaction chamber 21 of the heavy metal remover 2 can adopt a two-stage or four-stage structure. For example, a fourth stage can be added for further filtration when the material has a high heavy metal content. However, a three-stage structure balances efficiency and cost in most scenarios. This variant can be flexibly applied according to practical needs and brings higher purification accuracy.

[0020] The fluoride purification device 3 is equipped with an ultrasonic generator 31 and a lime slurry circulating spray system 32. The ultrasonic generator 31 operates at a frequency of 20-40 kHz and a power density of 0.5-2.0 W / cm³. The lime slurry circulating spray system 32 includes a storage tank, a circulating pump, and multiple spray heads. The multiple spray heads are distributed along the height of the fluoride purification device 3, and the spray angle of the spray heads can be adjusted within the range of 30°-90°, which enhances the contact area between the lime slurry and the fluoride, thereby improving the fluoride removal rate. The ultrasonic generator 31 is installed at the bottom of the device and connected to the cavity wall through a fixed bracket. The storage tank of the lime slurry circulating spray system 32 is located outside the device and is connected to the circulating pump through a pipeline. During operation, the fluoride purification device 3 receives material from the heavy metal remover 2. An ultrasonic generator 31 creates cavitation to break up the material particles. Simultaneously, a lime slurry circulating spray system 32 sprays lime slurry solution from multiple spray heads, with the coverage area maximized when the spray angle is adjusted to 45°. The circulating pump maintains the lime slurry concentration at 5-10%. The synchronized operation of the ultrasonic waves and spraying ensures a fluoride removal rate of over 95%. This collaborative mechanism improves reaction efficiency, reduces washing liquid consumption, and ensures that the fluoride content drops below 0.1%. The fluoride purification device 3 enhances reaction contact through ultrasound, thoroughly removing soluble fluorides and preventing plant growth stagnation. The circulating system also reduces environmental pollution and supports the sustainable operation of the device.

[0021] As an alternative, the frequency of the ultrasonic generator 31 can be fixed at 30kHz to optimize specific materials, or an auxiliary stirring paddle can be added to supplement the cavitation effect, improving the adaptability of the device to different types of phosphogypsum. The organic material bin 5 in the organic matter composite system is connected to the fermentation and composting unit 6 via a conveyor belt. The fermentation and composting unit adopts an aerobic fermentation process. The fermentation and composting unit 6 is equipped with adjustable-height ventilation ducts, which are connected to the composting degree detector 7 via a control system. The composting degree detector 7 is connected to the nutrient element additive 8. This connection structure, through the coordinated control of the conveyor belt, adjustable ventilation ducts, and composting degree detector, achieves integrated, continuous, and precise operation of organic materials from storage, fermentation and composting to nutrient fortification, significantly improving processing efficiency and ensuring the stability and high efficiency of the final matrix product. The ventilation ducts include a main ventilation duct 61 and branch ventilation ducts 62. The branch ventilation ducts 62 are connected to the main ventilation duct 61 and driven by a lifting mechanism, which can adjust the vertical position of the branch ventilation ducts within the fermentation and composting unit 6. After the composting degree detector 7 detects the temperature, oxygen content, and C / N ratio of the organic material, the control system calculates the optimal oxygen supply depth according to a preset algorithm. For example, when the temperature is >65℃ or the oxygen content is <10%, the oxygen supply depth H (cm) = K × (T - 60), where K = 0.5 is the adjustment coefficient and T is the detection temperature (℃); when the C / N ratio is <20, H is reduced by 30%. The algorithm is based on a linear regression model, and the input is the detection data. Next, the lifting mechanism adjusts the position of the branch ventilation duct 62. This adjustable structure enables precise oxygen supply and intelligent control of aerobic fermentation and composting treatment.

[0022] The main ventilation duct 61 is installed on the top of the fermentation and composting unit 6, and its inlet end is connected to an external air supply system. The branch ventilation duct 62 is installed vertically inside the fermentation and composting unit 6 and is arranged in a circular array along the inner wall. Its top end passes through the sliding seal at the top of the fermentation and composting unit 6 and is connected to the outlet of the main ventilation duct 61 through a flexible connecting hose. Air outlet holes are evenly opened on the bottom side wall of the branch ventilation duct 62, and its bottom end is set with a conical structure. The lifting mechanism includes a servo motor 63, a ball screw 64, a screw nut seat 65, and a guide rod 66. The ball screw 64 is vertically fixed inside the fermentation and composting unit 6 through a bearing seat. The servo motor 63 is fixed on the bracket at the top of the fermentation and composting unit 6, and its output shaft is connected to the top end of the ball screw 64 through a coupling. The screw nut seat 65 is threadedly connected to the ball screw 64. The guide rod 66 is vertically fixed on the bracket on the outer wall of the fermentation and composting unit 6. The screw nut seat 65 is slidably installed on the guide rod 66 and is fixedly connected to the top end of the branch ventilation duct 62 through a connecting flange.

[0023] During fermentation, peat, coconut coir, and sawdust are mixed in the organic material silo 5 at a weight ratio of 2:1:1 and fed into the fermentation and composting unit 6. The ventilation duct network 61 maintains an oxygen concentration of 10-15%, and the fermentation temperature is controlled at 50-60℃. When the composting degree detector 7 detects a local temperature exceeding 65℃, the corresponding branch ventilation duct 62 automatically descends under the drive of the lifting mechanism to enhance oxygen supply. The composting degree detector 7 monitors indicators such as the C / N ratio and germination index of the organic matter in real time. When the C / N ratio drops below 20, the ventilation duct gradually rises to reduce the oxygen supply intensity, thereby enhancing oxygen diffusion and heat dissipation in that area. The composting degree detector 7 monitors indicators such as the C / N ratio and germination index of the organic matter in real time. When the C / N ratio drops below 20, the ventilation duct gradually rises to reduce the oxygen supply intensity, preventing over-mineralization. Furthermore, when the germination index reaches 80% or higher, composting is complete. This adaptive ventilation mode, based on process parameters, fundamentally solves the problems of poor uniformity and lag response inherent in traditional static ventilation, significantly improving the efficiency of composting and the uniformity of substrate product quality. The composted material then enters the nutrient element adder 8, where fertilizers such as urea, diammonium phosphate, and potassium sulfate are added according to the different nutritional needs of various plants, adjusting the N:P:K ratio to 15:10:20, while also supplementing medium-quantity elements such as calcium, magnesium, and sulfur. This working principle ensures complete decomposition of organic matter and improves the nutritional stability of the substrate. The organic matter composite system ensures thorough composting through adjustable ventilation and real-time monitoring, avoiding the negative impact of unripe organic matter on plants. Simultaneously, the nutrient addition enhances the fertility of the substrate, meeting the needs of modern agriculture.

[0024] As a possible variation, the branches of the ventilation duct can be adjusted by rotation instead of lifting to accommodate different fermentation bed thicknesses and optimize fermentation uniformity. The substrate mixing system is connected to both the raw material pretreatment system and the organic matter composite system. The automatic batching machine 9 precisely dispenses materials according to a ratio of phosphogypsum: peat: perlite: vermiculite = 40:30:20:10. The automatic batching machine 9 is connected to a twin-shaft mixer 10, whose blades have adjustable angles. The water-retaining agent additive 11 and the microbial inoculant 12 are both connected to the twin-shaft mixer 10. Through the adjustable-angle mixing blades and precise material ratio control, combined with the simultaneous addition of water-retaining agents and microorganisms, the substrate mixing system ensures the uniformity of component distribution and functional integrity, thereby significantly improving the physical structural stability and biological activity consistency of the plant growth substrate. During the mixing process, the automatic batching machine 9 employs a high-precision electronic scale system to batch materials with an accuracy of ±1%. The materials enter the twin-shaft mixer 10, and the angle adjustment mechanism adjusts the blade angle to 45° to optimize shear force. The mixing speed is 20-60 r / min, and the mixing time is 15-20 minutes. During the mixing process, the water-retaining agent additive 11 adds high-molecular water-retaining materials such as sodium polyacrylate at 0.1-0.3% of the substrate weight to improve the water and fertilizer retention capacity of the substrate. The microbial inoculator 12 sprays fermented beneficial bacterial solution (viable bacteria count ≥10⁸ CFU / mL) into the substrate at an inoculation amount of 0.5-1.0% of the substrate weight. This collaboration improves the uniformity of distribution and effectively enhances the quality of the substrate.

[0025] The physical property control system is connected to the matrix proportioning and mixing system. The twin-shaft mixer 10 is connected to the porosity adjustment device 13, which is equipped with a vibrating sieve module 131 and is sequentially connected to the air permeability tester 14, the bulk density controller 15, and the particle size classifier 16. This sequence ensures step-by-step control of physical properties, realizing fully automatic, integrated, and precise control from porosity construction to bulk density compaction, significantly improving production efficiency and product uniformity.

[0026] The vibrating screening module 131 includes a vibrating motor, an eccentric block, and a multi-layer screen. The vibration frequency of the vibrating motor can be adjusted within the range of 10-50Hz. The mesh size of the multi-layer screen decreases sequentially from top to bottom, being 10mm, 5mm, 2mm, and 1mm respectively. The vibrating screening module 131 is connected to an online porosity detection device. The vibrating screening module 131 automatically adjusts according to the online porosity detection results. For example, when the porosity is below 60%, the vibration frequency increases to 40Hz; when the porosity is above 70%, the frequency decreases to 20Hz. The adjustment mechanism is implemented through a PLC controller, where frequency F (Hz) = reference value 30 + (measured porosity P - target value 65) × 0.5. Through the synergy of adjustable frequency vibration and gradient screening, and dynamic adjustment based on online detection results, precise and automated control of matrix porosity is achieved, fundamentally ensuring the stability and consistency of the product's physical structure. During the regulation process, the mixed substrate enters the porosity adjustment device 13. The pore structure of the substrate is adjusted by adding perlite and vermiculite of different particle sizes. The vibrating sieve module 131 adds perlite and vermiculite at a frequency of 30Hz to achieve a total porosity of 60-70%. The air permeability meter 14 measures the air permeability at 10-30 mL / min. By adjusting the substrate composition ratio and moisture content, the substrate bulk density is controlled within the range of 0.4-0.8 g / cm³. The particle size is then graded to 0.5-10 mm by the particle size classifier 16, optimizing physical properties and making it suitable for container cultivation. The physical performance regulation system ensures a balance between substrate air permeability and water retention through vibration regulation and monitoring, preventing root hypoxia or waterlogging and improving plant survival rate. The microbial agent fermentation tank 17 is equipped with a temperature control system and an automatic pH adjustment system, which are connected sequentially to an enzyme additive adder 18, a growth regulator mixer 19, and a micronutrient chelator 20. The micronutrient chelator 20 is connected to the porosity adjustment device 13. The mixed substrate first enters the porosity adjustment device 13. During this process, the microbial agents, enzyme preparations, growth regulators, and chelated trace elements prepared by the bioactivity improvement system are simultaneously added and mixed. Subsequently, the substrate undergoes physical property testing and fine-tuning through an air permeability tester 14, a bulk density controller 15, and a particle size classifier 16, ultimately yielding a high-quality plant growth substrate with excellent physical properties and abundant bioactivity. This integration of biological elements, through sequential addition and regulation, enhances the substrate's bio-promoting effect, promoting plant root development and stress resistance. During the improvement process, the microbial agent fermentation tank 17 cultivates beneficial microorganisms such as AM bacteria, PGPR bacteria, and phosphate-solubilizing bacteria at a fermentation temperature of 28-32℃, a pH of 6.5-7.0, and a fermentation cycle of 7-10 days. The enzyme preparation adder 18 adds cellulase, amylase, and other biological enzymes at a dosage of 0.01-0.05% of the substrate weight, improving the efficiency of organic matter decomposition. The growth regulator mixer 19 adds growth promoters such as humic acid and amino acids. The amount of humic acid added is 1-3% of the substrate weight, and the amount of amino acids added is 0.1-0.5%.The trace element chelator 20 prepares chelated trace elements such as iron, zinc, and boron, and improves the bioavailability of trace elements through EDTA or citric acid chelation technology. This mechanism enhances biological activity and improves the decomposition of organic matter and nutrient availability. In a complete embodiment, the device of this invention operates according to the following process to prepare a high-quality plant growth substrate: Raw material pretreatment stage: The phosphogypsum raw material is output from the phosphogypsum storage silo 1 and passes sequentially through the heavy metal removal device 2 and the fluoride purification device 3, effectively removing heavy metal ions such as arsenic, lead, and cadmium, as well as harmful impurities such as soluble fluorides. The purified phosphogypsum enters the pH adjuster 4, where a quantitative amount of limestone powder (CaCO3) is added to precisely adjust its pH value to approximately neutral 7.0, forming a safe pretreated phosphogypsum.

[0027] Organic matter compounding and composting stage: Organic materials such as peat, coconut coir, and sawdust are transported from the organic material silo 5 to the fermentation composting unit 6. During composting, the ventilation duct network 61 dynamically adjusts the oxygen supply intensity based on parameters such as temperature, oxygen concentration, and C / N ratio fed back in real time by the composting degree detector 7, ensuring that aerobic fermentation takes place within the optimal temperature range of 50-60℃, generating fully composted and stable organic matter. The composted organic matter is then transported to the nutrient element additive unit 8, where basic nutrients such as nitrogen, phosphorus, and potassium are added according to a preset formula to complete the nutritional fortification of the organic matter.

[0028] Matrix proportioning and mixing stage: Pretreated phosphogypsum and nutrient-fortified organic matter are precisely proportioned by automatic batching machine 9 according to an optimized ratio of phosphogypsum: peat: perlite: vermiculite = 40:30:20:10. The proportioned materials enter the twin-shaft mixer 10 for preliminary mixing. During this process, water-retaining agent additive 11 and microbial inoculator 12 add water-retaining agent and spray fermented beneficial bacteria solution into the mixer, respectively, to achieve uniform mixing and functionalization of the basic components.

[0029] Physical property synergistic bioactivity improvement stage: The initially mixed matrix enters the physical property regulation system. First, the matrix is ​​transported to the porosity adjustment device 13, where it is mixed with porosity adjustment materials such as perlite and vermiculite to optimize its pore structure. Simultaneously, a composite active agent prepared by the bioactivity improvement system, composed of microbial agents produced by the microbial agent fermentation tank 17, enzymes added by the enzyme preparation adder 18, growth promoters added by the growth regulator mixer 19, and chelated trace elements provided by the trace element chelator 20, is added to the porosity adjustment device 13, ensuring uniform distribution of bioactive components from the initial formation of the matrix's physical framework. Subsequently, the matrix undergoes permeability verification via the permeability tester 14, is adjusted to the ideal bulk density by the bulk density controller 15, and finally, is sieved by the particle size classifier 16 to obtain a finished matrix with uniform particle size.

[0030] Finished product output: After the above continuous pretreatment, compounding, mixing, regulation and improvement process, a high-quality plant growth substrate with excellent physical and chemical properties, moderate porosity, good air permeability, suitable bulk density, comprehensive nutrition and high biological activity is finally output, realizing the goal of efficient utilization of phosphogypsum resources.

[0031] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although the utility model has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of this utility model.

Claims

1. A device for preparing plant growth substrate using phosphogypsum, characterized in that: The device for preparing plant growth substrate from phosphogypsum includes a raw material pretreatment system, an organic matter composite system, a substrate ratio mixing system, a physical property regulation system, and a bioactivity improvement system. The raw material pretreatment system includes a phosphogypsum storage silo (1), a heavy metal remover (2), a fluoride purification device (3), and a pH regulator (4) connected in sequence. The heavy metal remover (2) is equipped with multiple reaction chambers, each of which is equipped with a pH sensor (22) and a heavy metal ion concentration detector (21). The fluoride purification device (3) is equipped with an ultrasonic generator (31) and a lime milk circulating spray system (32). The organic matter composite system includes an organic material silo (5), a fermentation and composting device (6), a composting degree detector (7), and a nutrient element additive (8) connected in sequence. The fermentation and composting device (6) is equipped with an adjustable-height ventilation duct, and the ventilation duct is connected to the composting degree detector (7) through a control system. The substrate mixing system includes an automatic batching machine (9), a twin-shaft mixer (10) connected in sequence, and a water-retaining agent additive (11) and a microbial inoculum (12) respectively connected to the twin-shaft mixer (10); the pH regulator (4) and the nutrient element additive (8) are both connected to the automatic batching machine (9); the mixing blades of the twin-shaft mixer (10) have an adjustable angle structure; The physical performance control system includes a porosity adjustment device (13), an air permeability tester (14), a bulk density controller (15), and a particle size classifier (16) connected in sequence. The porosity adjustment device (13) is connected to a twin-shaft mixer (10). The porosity adjustment device (13) is equipped with a vibrating sieve module (131). The bioactivity improvement system includes a microbial agent fermentation tank (17), an enzyme preparation adder (18), a growth regulator mixer (19), and a trace element chelator (20) connected in sequence. The trace element chelator (20) is connected to the porosity adjustment device (13). The microbial agent fermentation tank (17) is equipped with a temperature control system and an automatic pH adjustment system.

2. The apparatus for preparing plant growth substrate from phosphogypsum according to claim 1, characterized in that: The multi-stage reaction chambers are a three-stage series structure. The first-stage reaction chamber is equipped with a sodium sulfide dosing port, the second-stage reaction chamber is equipped with a sodium hydroxide dosing port, and the third-stage reaction chamber is equipped with a flocculant dosing port. The detection data of the pH sensor (22) and the heavy metal ion concentration detector (21) are connected to the central control system through a data transmission line. The central control system automatically adjusts the dosage of chemical reagents and the reaction time in each stage of the reaction chamber according to the detection data. Each reaction chamber is equipped with a precipitate discharge port at the bottom, and the precipitate discharge port is controlled to open and close by an electric valve.

3. The apparatus for preparing plant growth substrate from phosphogypsum according to claim 1, characterized in that: The lime slurry circulating spray system (32) includes a storage tank, a circulating pump and multi-layer spray heads. The multi-layer spray heads are distributed along the height direction of the fluoride purification device (3). The spray angle of the spray heads can be adjusted within the range of 30°-90°. The ultrasonic generator (31) works synchronously with the lime slurry circulating spray system (32) to enhance the reaction contact area between lime slurry and fluoride in phosphogypsum through ultrasonic cavitation effect.

4. The apparatus for preparing plant growth substrate from phosphogypsum according to claim 1, characterized in that: The ventilation duct includes a main ventilation duct (61) and several branch ventilation ducts (62). The branch ventilation ducts (62) are connected to the main ventilation duct (61) and driven by a lifting mechanism. The lifting mechanism can adjust the vertical position of the branch ventilation ducts (62) in the fermentation and composting device (6).

5. The apparatus for preparing plant growth substrate from phosphogypsum according to claim 4, characterized in that: The main ventilation duct (61) is installed on the top of the fermentation and composting unit (6), and its inlet end is connected to an external air supply system; the branch ventilation duct (62) is installed vertically inside the fermentation and composting unit (6) and is arranged in a circular array along the inner wall. Its top end passes through the sliding seal at the top of the fermentation and composting unit (6) and is connected to the outlet of the main ventilation duct (61) through a flexible connecting hose. Air outlet holes are evenly opened on the bottom side wall of the branch ventilation duct (62), and its bottom end is set as a conical structure; the lifting mechanism includes a servo motor (63), a ball screw (64), and a screw nut seat (65). The ball screw (64) is vertically fixed inside the fermentation and composting unit (6) via a bearing seat, and the servo motor (63) is fixed on the bracket at the top of the fermentation and composting unit (6). Its output shaft is connected to the top of the ball screw (64) via a coupling. The screw nut seat (65) is threadedly connected to the ball screw (64). The guide rod (66) is vertically fixed on the bracket on the outer wall of the fermentation and composting unit (6). The screw nut seat (65) is slidably installed on the guide rod (66) and fixedly connected to the top of the branch ventilation duct (62) via a connecting flange.

6. The apparatus for preparing plant growth substrate from phosphogypsum according to claim 1, characterized in that: The vibrating screening module (131) includes a vibrating motor, an eccentric block and a multi-layer screen. The vibration frequency of the vibrating motor can be adjusted within the range of 10-50Hz. The mesh size of the multi-layer screen decreases from top to bottom, and is 10mm, 5mm, 2mm and 1mm respectively. The vibrating screening module (131) is connected to an online porosity detection device.

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