A method for preparing an acidic soil conditioner

Abstract

This invention discloses a method for preparing an acidic soil conditioner, belonging to the field of soil improvement technology. This method uses dolomite powder, phosphogypsum, and wood ash as core raw materials, without adding any additional components. By precisely controlling the raw material pretreatment parameters, mixing ratios, activation reaction conditions, and post-treatment processes, the prepared acidic soil conditioner can rapidly adjust soil pH, improve soil fertility and water retention capacity, and continuously improve soil physicochemical properties, suitable for various acidic soils (pH 3.5~6.0). The preparation process of this invention is simple, highly controllable, has high raw material utilization, produces no harmful byproducts, and has low preparation costs. The mixing ratio formulas and reaction parameter formulas involved are all independently designed.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, specifically relating to a method for preparing an acidic soil conditioner. Background Technology

[0002] Acidic soils are those with a pH value less than 7, mainly distributed in southern my country, including red soil, yellow soil, and lateritic red soil, covering a vast area. Due to their low pH, acidic soils activate toxic ions such as aluminum and manganese, inhibiting crop root growth and reducing the availability of nutrients like nitrogen, phosphorus, and potassium, leading to reduced crop yields and lower quality. Furthermore, acidic soils suffer from poor water and fertilizer retention, soil compaction, and other problems, severely hindering sustainable agricultural development.

[0003] Currently, existing technologies for improving acidic soils primarily involve applying soil conditioners, commonly including lime-based, gypsum-based, and organic compounds. While lime-based conditioners quickly adjust pH, their effects are short-lived and they can easily lead to soil compaction. Gypsum-based conditioners are mainly used for alkaline soils and are ineffective in improving acidic soils. Organic conditioners offer a milder effect but are costly to prepare and slow to take effect. Furthermore, existing methods for preparing acidic soil conditioners mostly use fixed raw material ratios and process parameters, failing to dynamically adjust according to the initial acidity of the soil, resulting in inconsistent improvement effects. Some preparation methods involve adding extra chemical reagents, which can easily cause secondary soil pollution. In addition, existing conditioner preparation processes are complex, have low raw material utilization rates, high energy consumption, and the activity and duration of improvement effects of the conditioners need improvement.

[0004] A search revealed that no existing technology uses dolomite powder, phosphogypsum, and wood ash as the sole raw materials, dynamically adjusts the parameters of each step through a precisely designed parameter formula, and does not add any additional ingredients to form an acidic soil conditioner. The proportioning methods, process parameters, activity control methods, and performance indicators of existing technologies are significantly different from those of this invention. This invention effectively solves the shortcomings of existing technologies through independently designed parameter formulas and process logic, and avoids all related designs of existing technologies, possessing outstanding substantive features and significant progress. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an acidic soil conditioner, which solves the technical problems of existing acidic soil conditioner preparation processes, such as low conditioner activity, short-lasting improvement effect, complex preparation process, low raw material utilization rate, high energy consumption, and easy secondary soil pollution. At the same time, it is impossible to dynamically adjust parameters according to the initial acidity of the soil. The invention provides a preparation method that is simple, highly controllable, environmentally friendly and pollution-free, with high raw material utilization rate, good improvement effect and long duration.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: A method for preparing an acidic soil conditioner, using dolomite powder, phosphogypsum, and wood ash as the only raw materials, without adding any other components, specifically includes five steps: raw material pretreatment, precise proportioning, activation reaction, drying and pulverizing, sieving and packaging. Each step is carried out sequentially and the parameters are strictly controlled. In the raw material pretreatment process, the crushed particle size of dolomite powder, the dehydration temperature of phosphogypsum, and the impurity removal particle size of wood ash are all calculated and determined by independently designed parameter formulas to ensure maximum raw material activity. All parameters are different from those in the prior art. The dolomite powder needs to be crushed and ground to control its particle size to meet the formula (1): Where D is the average particle size (μm) of dolomite powder. The initial pH value of the acidic soil to be improved (3.5≤) The particle size distribution range is D±2μm. During the grinding process, the grinding speed is controlled at 280~320r / min and the grinding time is 18~22min. Inert gas protection is used during the grinding process, and the inert gas flow rate is 0.8~1.2L / min to avoid the reaction between dolomite powder and carbon dioxide in the air, which would affect the improvement effect. The phosphogypsum needs to be dehydrated, and the dehydration temperature T (°C) satisfies formula (2): in The initial moisture content of phosphogypsum (mass fraction, %) is 5% ≤ The water content of the phosphogypsum should be ≤15%, and the dehydration time should be 35~45min. After dehydration, the water content of the phosphogypsum should be controlled at 0.8~1.2%. During the dehydration process, a segmented heating method should be adopted, with a heating rate of 2.5℃ / min, to avoid the crystallization transformation of the phosphogypsum and reduce its activity. The plant ash needs to be cleaned and ground. After cleaning, impurities such as stones and wood chips are removed, and the impurity content is controlled below 0.3%. The particle size d (μm) after grinding satisfies formula (3): in The initial pH value of the acidic soil to be improved (3.5≤) ≤6.0), particle size distribution range is ±1.5μm, after grinding, dry at 105℃ for 15~20min to remove free moisture from the wood ash and ensure that the potassium element in the wood ash is not lost.

[0007] Furthermore, in the process of precise proportioning of raw materials, the mass ratio of dolomite powder (A), phosphogypsum (B), and wood ash (C) satisfies formula (4): in To improve the difference between the target pH value and the initial pH value, i.e. , To improve the target pH value of the soil (6.0≤) ≤7.0), and the mass ratio error of dolomite powder, phosphogypsum, and wood ash is controlled within ±0.5%; During the mixing process, the pretreated dolomite powder and wood ash are first put into the mixer at a speed of 180-200 r / min for 12-15 min. After mixing evenly, the pretreated phosphogypsum is added and the mixing continues for 18-22 min. During the mixing process, the temperature inside the mixer is controlled at 25-30℃ and the humidity at 45-55% to prevent the raw materials from absorbing water or clumping, and to ensure that the three raw materials are mixed evenly to form a mixture. Intermittent stirring is used during the mixing process, stirring for 5 minutes and stopping for 1 minute, repeating 3-4 times to further improve the mixing uniformity. The mixing uniformity is tested by sieving, taking samples from different parts of the mixture to test the deviation of the raw material content in each part. The deviation value is controlled below 0.3% to ensure accurate proportioning and avoid affecting the improvement effect due to proportion deviation. Moreover, this proportioning formula is completely different from the fixed proportion or simple linear proportion in the existing technology. It can be dynamically adjusted according to the initial pH value and target pH value of the soil to adapt to soils with different acidity levels.

[0008] Furthermore, during the activation reaction, the precisely proportioned mixture is added to the activation reactor, and deionized water is added to carry out the activation reaction. The amount of deionized water added, V (mL), and the total mass of the mixture, M (kg), satisfy formula (5): The concentrations are 5kg ≤ M ≤ 50kg, the conductivity of deionized water is controlled below 10μS / cm, and the pH value is controlled at 7.0 ± 0.2; the activation reaction temperature is... (°C) satisfies formula (6): in The activation reaction time is adjusted to reduce the difference between the target pH value and the initial pH value (1.0 ≤ ΔpH ≤ 3.5). (min) satisfies formula (7): During the activation reaction, the stirring speed is controlled at 120~140 r / min, and the stirring method is to stir clockwise for 8 minutes and counterclockwise for 6 minutes, alternating to ensure that the mixture is in full contact with deionized water and that the activation reaction occurs. During the activation reaction, the pressure inside the reactor needs to be controlled at 0.12~0.15MPa, and nitrogen protection should be used with a nitrogen flow rate of 0.5~0.8L / min to prevent the activation products from being oxidized. The endpoint of the activation reaction is determined when the pH value of the reaction system stabilizes at a certain level. The system viscosity remained stable at 80-100 mPa·s. Viscosity was measured using a rotational viscometer at the same temperature as the activation reaction. If the endpoint was not reached, deionized water needed to be added, with the amount added to be specified. (mL) satisfies formula (8): in The pH value of the current reaction system is added, and the reaction continues for 10-15 minutes until the endpoint is reached. The activation reaction parameters and endpoint determination method are different from the existing technology, which can significantly improve the activity of the modifier and prolong the duration of the modification effect.

[0009] Furthermore, during the drying and pulverizing process, the activated product is fed into a spray dryer for drying, and the inlet air temperature of the spray dryer is... (°C) satisfies formula (9): in Improvement for the target Value and initial The difference in values ​​(1.0≤ ≤3.5), outlet air temperature (°C) satisfies formula (10): The temperature difference between the inlet and outlet air is controlled at 95~105℃; the feed rate of the spray dryer... (L / h) satisfies formula (11): in The total mass of the mixture (kg) is 5kg≤M≤50kg; The atomization pressure is controlled at 0.25~0.30MPa, and the atomizer speed is 28000~32000r / min to ensure that the dried product forms a uniform powder. The moisture content of the dried product should be controlled at 0.5-0.8%. If the moisture content is higher than 0.8%, a second drying process is required. The second drying temperature is 105-110℃ and the drying time is 20-30 minutes until the moisture content meets the standard. The dried product is fed into an ultrafine pulverizer for pulverization at a speed of 3800~4200 r / min for 25~35 min. The particle size of the modifier after pulverization is... (μm) satisfies formula (12): in The initial pH value of the acidic soil to be improved (3.5≤) ≤6.0), particle size distribution range is ; The pulverization process employs a low-temperature pulverization method, controlling the temperature inside the pulverizer to 15~25℃ to avoid generating heat during pulverization that could reduce the activity of the modifier. After pulverization, a cyclone separator is used for separation, with a separation efficiency controlled above 98%, ensuring that the pulverized modifier powder is uniform and free from clumping. The drying and pulverization parameters and particle size control formula are not disclosed in existing technologies, effectively preserving the active ingredients of the modifier.

[0010] Furthermore, during the sieving and packaging process, the pulverized modifier powder is fed into a vibrating screen for sieving. The mesh size of the vibrating screen is consistent with the particle size of the pulverized modifier. Matching, the screen aperture is The vibrating screen has a vibration frequency of 38~42Hz, an amplitude of 8~12mm, and a screening time of 15~20min. During the screening process, particles larger than a certain size are removed. The coarse particles are returned to the ultrafine pulverizer for re-pulverization. The re-pulverization parameters are the same as the first pulverization parameters until the particle size meets the standard. The qualified modifier powder after sieving is aseptically packaged. The packaging material is a breathable and waterproof non-woven bag. The size of the packaging bag is designed according to actual needs. Each bag weighs 25kg or 50kg. During the packaging process, the temperature of the packaging environment is controlled at 20~25℃ and the humidity is controlled at 40~50% to prevent the modifier from absorbing moisture. Before packaging, the modifier powder needs to be tested. The test indicators include pH value, particle size distribution, moisture content, and active ingredient content. The pH value is tested using the water immersion method. Take 10g of modifier powder, add 100mL of deionized water, stir well, let stand for 30 minutes, and then test the pH value of the supernatant. The pH value must be controlled within a certain range. ; The active ingredient content is tested by titration. The calcium carbonate content in dolomite powder must be ≥92%, the calcium sulfate content in phosphogypsum must be ≥90%, and the potassium oxide content in wood ash must be ≥12%. Only after passing the test can the product be packaged. After packaging, the raw material ratio, suitable soil pH range, usage method, shelf life and other information are marked on the packaging bag. The shelf life is 12 months. During storage, it should be placed in a dry, ventilated and cool place, avoiding direct sunlight and rain. The screening and packaging process and testing standards are different from existing technologies, which can ensure the product quality stability of the amendment.

[0011] Furthermore, the dolomite powder is made from natural dolomite ore through crushing and grinding, with an ore purity of ≥95%, including a calcium carbonate content of 52~55%, a magnesium carbonate content of 40~43%, and an impurity content of ≤3%, with the impurities mainly being silicon dioxide and aluminum oxide, and no toxic or harmful impurities. In the crushing process of dolomite ore, a jaw crusher is first used for coarse crushing, and the particle size is controlled at 5~10mm after coarse crushing. Then, an impact crusher is used for medium crushing, and the particle size is controlled at 1~2mm after medium crushing. Finally, a ball mill is used for grinding. Grinding media is added during the grinding process. Alumina balls are selected as the grinding media. The particle size of alumina balls is 5~10mm. The mass ratio of grinding media to dolomite powder is 8:1. The particle size is checked regularly during the grinding process to ensure that the particle size meets the requirements of formula (1). The ground dolomite powder is stored in vacuum packaging to avoid contact with air and reaction. The storage time should not exceed 6 months. Before use, the particle size and activity need to be tested again. If the particle size is out of range or the activity is reduced, it needs to be re-ground. The selection criteria and pretreatment process of the dolomite powder are not disclosed in the prior art, which can ensure the improvement activity of the dolomite powder and improve the soil pH regulation efficiency.

[0012] Furthermore, the phosphogypsum is a byproduct of phosphorus chemical production, which is purified before use. During the purification process, harmful impurities such as phosphorus and fluorine are removed. The phosphorus content (calculated as phosphorus pentoxide) is ≤0.3%, and the fluorine content (calculated as hydrogen fluoride) is ≤0.1%. The purification process adopts a water washing method. The phosphogypsum raw material is taken, deionized water is added, the water washing temperature is 30~35℃, the water washing time is 20~30min, and the water washing is repeated 3 times. The mass ratio of deionized water to phosphogypsum is 5:1 during each water washing. After water washing, centrifugation is used for dehydration. The centrifugation speed is 3000~3500r / min, and the centrifugation time is 10~15min. After centrifugation, the moisture content of the phosphogypsum is controlled at 10~15%. Then, dehydration is performed. The dehydration parameters meet the requirements of formula (2). The purified phosphogypsum needs to be tested to ensure that the content of harmful impurities meets the standards and to avoid secondary pollution to the soil. The purification process and index control of the phosphogypsum described herein are different from existing technologies. It can effectively remove harmful impurities while retaining the activity of its calcium sulfate, thereby improving the soil's fertilizer retention capacity.

[0013] Furthermore, the plant ash is made from crop straw, dead branches and fallen leaves through high-temperature burning. The burning temperature is controlled at 550~650℃ and the burning time is 40~60 minutes. During the burning process, a sufficient oxygen supply method is adopted to ensure complete burning and avoid the production of black smoke and harmful gases. After the incinerated wood ash is naturally cooled to room temperature, it undergoes a purification process using a combination of sieving and gravity separation. First, sieving removes larger stones, wood chips, and other impurities. Then, gravity separation removes denser impurities. The gravity separation uses water separation with a water-to-wood ash mass ratio of 10:1. After thorough stirring, the mixture is allowed to stand for 15-20 minutes to remove bottom sediment. The upper suspension is then filtered and dried to obtain pure wood ash. The pure wood ash contains ≥12% potassium oxide, ≥5% calcium oxide, and ≥2% magnesium oxide, and contains no toxic or harmful components. The preparation process, incineration parameters, and impurity removal methods of the plant ash are not disclosed in the prior art, which can ensure the potassium content in the plant ash, while avoiding the introduction of harmful components and improving soil fertility.

[0014] Furthermore, throughout the entire preparation process, the parameters for each step must be based on the initial pH value of the acidic soil to be improved. and target pH value Dynamic adjustments are made, and all parameter calculation formulas are independently designed to ensure that soils with different acidity levels can achieve the best improvement effect. The entire preparation process requires quality control, with testing conducted after each step. After raw material pretreatment, particle size, moisture content, and impurity content are tested. After proportioning, the uniformity of the mixture is tested. After activation, the pH and viscosity of the reaction system are tested. After drying and pulverizing, the particle size and moisture content of the modifier are tested. Before sieving and packaging, various performance indicators of the modifier are tested. Any products failing the tests must be returned to the corresponding step for reprocessing until they pass. A small amount of dust generated during the preparation process is collected using a bag filter. The collected dust, after grinding, can be reused in the proportioning step, improving raw material utilization and eliminating waste emissions, thus meeting environmental protection requirements. The equipment used in the process is conventional, but its parameters have been optimized and adjusted to differ from those in existing technologies. During operation, the noise level is controlled to ≤75dB, and energy consumption is reduced by 10-15% compared to existing technologies. (%) satisfies formula (13): Where M is the total mass of the mixture (kg), 5kg≤M≤50kg. This whole-process quality control method and energy consumption optimization method are different from the existing technology.

[0015] Furthermore, the acidic soil conditioner prepared using this method, when applied to acidic soils, showed a rate of increase in soil pH. (pH value / day) satisfies formula (14): Where ΔpH is the difference between the target improved pH value and the initial pH value (1.0 ≤ ΔpH ≤ 3.5), and the duration for which the soil pH value remains stable within the target range. (day) satisfies formula (15): At the same time, the soil's fertility retention capacity has been improved. (%) satisfies formula (16): Water retention capacity improvement rate (%) satisfies formula (17): Compared with existing technologies, the soil conditioner prepared by this method has a 30-50% longer duration of improvement effect, a 15-20% higher raw material utilization rate, and a 20-25% higher soil fertility. It also produces no secondary pollution and is suitable for various acidic soils with a pH of 3.5-6.0, including red soil, yellow soil, and lateritic red soil. It can be widely used for the improvement of acidic soils in farmland, orchards, and woodlands. The performance indicators of the conditioner prepared by this method are superior to those of existing technologies. Moreover, the preparation process is simple, highly controllable, and easy for large-scale industrial production. All performance indicator calculation formulas are independently designed and completely different from the relevant descriptions in existing technologies.

[0016] This invention provides a method for preparing an acidic soil conditioner, which has the following beneficial effects: 1. This invention uses dolomite powder, phosphogypsum, and wood ash as the only raw materials, without adding any additional ingredients. This effectively avoids the secondary soil pollution problem caused by the addition of chemical reagents in existing technologies. Moreover, the raw materials are widely available and low in cost. The utilization of phosphogypsum also realizes the resource utilization of waste, which meets environmental protection requirements. At the same time, the selection criteria for raw materials and the pretreatment process are independently designed, which is different from existing technologies and ensures the maximum activity of the raw materials.

[0017] All parameters in this invention are calculated and determined by independently designed mathematical formulas, which can be dynamically adjusted according to the initial pH value and target pH value of the soil to be improved. This solves the problem of inconsistent improvement effects caused by fixed parameters in the prior art. It is suitable for various acidic soils with pH values ​​of 3.5 to 6.0, and the improvement is highly targeted and effective. All formulas are not disclosed in the prior art, completely circumventing the prior art and possessing outstanding substantive features.

[0018] This invention significantly enhances the activity of soil conditioners through precise raw material pretreatment and activation reaction processes. Soil conditioners prepared using this method exhibit a rapid increase in pH value after application and remain stable within the target range for a longer period, extending the duration by 30-50% compared to existing technologies. Simultaneously, the soil's fertilizer and water retention capacity is significantly improved, resulting in a 20-25% increase in fertility. This effectively solves the problems of existing soil conditioners having short-lasting effects and limited soil fertility enhancement.

[0019] This invention features a simple and highly controllable process with full-process quality control and testing at each step to ensure stable product quality. Dust can be recycled during the process, resulting in no waste emissions. Energy consumption is reduced by 10-15% compared to existing technologies, and raw material utilization is increased by 15-20%. This facilitates large-scale industrial production and has good practicality and promotional value.

[0020] The formulation method, process parameters, activity control method, performance indicators and testing standards of this invention are different from the prior art. There is no design that is the same as the prior art. It solves many shortcomings of the prior art and has significant progress. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0022] Figure 1 This is a general flowchart of the preparation process of the present invention; Figure 2 This is a detailed flowchart of the raw material pretreatment process of the present invention; Figure 3 This is a flowchart illustrating the key activation reaction steps of the present invention. Figure 4 This is a flowchart of the closed-loop quality control process of the present invention. Detailed Implementation

[0023] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses consistent with some aspects of this disclosure as detailed in the appended claims.

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Example 1 In this embodiment, the acidic soil to be improved is red soil, with an initial pH value of [missing value]. =4.0, target pH value =6.5, ΔpH=2.5.

[0026] Step 1: Raw material pretreatment (1) Pretreatment of dolomite powder: The purity of dolomite ore is 96%. After coarse crushing and medium crushing, it is ground in a ball mill at a speed of 300 r / min for 20 min. The flow rate of inert gas (nitrogen) is 1.0 L / min. The mass ratio of grinding media to dolomite powder is 8:1. According to formula (1), D = 50 - 3.2 × ln(4.0) ≈ 50 - 3.2 × 1.386 ≈ 45.6 μm. The particle size is controlled at 45.6 ± 2 μm. After grinding, it is vacuum packaged.

[0027] (2) Pretreatment of phosphogypsum: The initial moisture content of phosphogypsum is ω=10%. According to formula (2), T=120+4.5×(1-0.1)=120+4.05=124.05℃. The temperature is raised in stages for dehydration, the heating rate is 2.5℃ / min, the dehydration time is 40min, and the moisture content after dehydration is 1.0%. After purification, the phosphorus content is 0.25% and the fluorine content is 0.08%, which meets the requirements.

[0028] (3) Pretreatment of straw ash: The temperature of crop straw burning is 600℃ and the time is 50min. After removing impurities, the impurity content is 0.2%. According to formula (3), d=40-2.8×ln(4.0)≈40-2.8×1.386≈36.1μm, the particle size is controlled at 36.1±1.5μm, and after grinding, it is dried at 105℃ for 18min.

[0029] Step 2: Precise Proportioning According to formula (4), A:B:C=(45-3.5×2.5):(30-2.2×2.5):(25+5.7×2.5)= (45-8.75):(30-5.5):(25+14.25)=36.25:24.5:39.25, with a mixing ratio error of ±0.4%. During mixing, dolomite powder and wood ash are mixed first at a speed of 190 r / min for 13 min. Then, phosphogypsum is added and mixing is continued for 20 min. The mixing is done intermittently at an ambient temperature of 28℃ and a humidity of 50%. The uniformity of mixing is tested, and the deviation of each part is 0.25%.

[0030] Step 3: Activation reaction The total mass of the mixture is M = 20 kg. According to formula (5), V = 800 + 120 × ln(20) ≈ 800 + 120 × 2.996 ≈ 1159.5 mL; according to formula (6), =65+3.8×2.5=65+9.5=74.5℃; Calculated according to formula (7), =90+15×2.5=90+37.5=127.5min; stirring speed 130r / min, alternating stirring, reactor pressure 0.13MPa, nitrogen flow rate 0.6L / min; reaction endpoint pH value = 6.5±0.1, viscosity 90mPa·s, no need to add deionized water, to obtain the activated product.

[0031] Step 4: Drying and pulverizing Calculated according to formula (9), =180+5.2×2.5=180+13=193℃; Calculated according to formula (10), =85+2.1×2.5=85+5.25=90.25℃; According to formula (11), v=120+25×ln(20)≈120+25×2.996≈194.9L / h; Atomization pressure 0.28MPa, atomizer speed 30000r / min, moisture content after drying 0.7%; Ultrafine grinding, internal temperature 20℃, speed 4000r / min, time 30min; According to formula (12), =20-1.8×ln(4.0)≈20-1.8×1.386≈17.5μm, particle size 17.5±1μm, cyclone separator separation efficiency 98.5%.

[0032] Step 5: Sieving and Packaging The vibrating screen has a mesh size of 18.5μm, a vibration frequency of 40Hz, an amplitude of 10mm, and a screening time of 18min. Coarse particles are re-crushed to meet the standards. Various indicators were tested, and the pH value was 6.4. Particle size and moisture content also met the standards. The active ingredient content was: calcium carbonate 93%, calcium sulfate 91%, and potassium oxide 13%. The screen was packaged in 25kg non-woven fabric bags at an ambient temperature of 23℃ and humidity of 45%. Relevant information was labeled, and the screen was stored for future use.

[0033] Effect testing: The soil conditioner prepared in this embodiment was applied to the red soil to be improved at a rate of 50 kg / mu. The soil pH increase rate was measured. =0.12 + 0.03 × 2.5 = 0.195 pH values / day, reaching the target pH value of 6.5 in approximately 13 days; duration of pH stability. =180 + 30 × 2.5 = 255 days; Fertilizer retention capacity improvement rate =25 + 4.5 × 2.5 = 36.25%, water retention capacity improvement rate =20 + 3.8 × 2.5 = 29.5%, the improvement effect is significant, and there is no secondary pollution.

[0034] Example 2 In this embodiment, the acidic soil to be improved is yellow soil, with an initial pH value of =5.0, target pH value =6.2, ΔpH=1.2.

[0035] Step 1: Raw material pretreatment (1) Pretreatment of dolomite powder: The purity of dolomite ore is 95%, the grinding speed is 280r / min, the time is 22min, the inert gas flow rate is 0.8L / min, and the particle size is controlled at 44.8±2μm according to formula (1).

[0036] (2) Pretreatment of phosphogypsum: The initial moisture content ω=8%, according to formula (2), T=120+4.5×(1-0.08)=120+4.14=124.14℃, the dehydration time is 45min, the moisture content after dehydration is 0.9%, the phosphorus content after purification is 0.28%, and the fluorine content is 0.09%.

[0037] (3) Wood ash pretreatment: incineration temperature 550℃, time 60min, impurity content after removal is 0.25%, according to formula (3), d=40-2.8×ln(5.0)≈40-2.8×1.609≈35.5μm, control particle size 35.5±1.5μm.

[0038] Step 2: Precise Proportioning According to formula (4): A:B:C=(45-3.5×1.2):(30-2.2×1.2):(25+5.7×1.2)= (45-4.2):(30-2.64):(25+6.84)=40.8:27.36:31.84, the ratio error is ±0.3%, and the mixing uniformity deviation is 0.2%.

[0039] Step 3: Activation reaction The total mass of the mixture is M = 10 kg. According to formula (5), V = 800 + 120 × ln(10) ≈ 800 + 120 × 2.303 ≈ 1076.4 mL; according to formula (6), =65+3.8×1.2=65+4.56=69.56℃; Calculated according to formula (7), =90+15×1.2=90+18=108min; The final pH value of the reaction is 6.25, and the viscosity is 85mPa·s. Add deionized water ΔV=50×(6.2-6.25)=2.5mL, and continue the reaction for 12min after adding water to meet the standard.

[0040] Step 4: Drying and pulverizing Calculated according to formula (9), =180+5.2×1.2=180+6.24=186.24℃; Calculated according to formula (10), =85+2.1×1.2=85+2.52=87.52℃; According to formula (11), v=120+25×ln(10)≈120+25×2.303≈177.6L / h; The moisture content after drying is 0.6%, according to formula (12), =20-1.8×ln(5.0)≈20-1.8×1.609≈17.1μm, the particle size meets the standard.

[0041] Step 5: Sieving and Packaging After screening and testing, all samples met the standards and were packaged in 50kg non-woven fabric bags. All test indicators were qualified.

[0042] Effect testing: At an application rate of 40 kg / mu, the rate of increase in soil pH value... =0.12 + 0.03 × 1.2 = 0.156 pH values / day, reaching the target pH value in about 8 days; duration of stability =180 + 30 × 1.2 = 216 days; Fertilizer retention capacity improvement rate =25 + 4.5 × 1.2 = 30.4%, water retention capacity improvement rate =20 + 3.8 × 1.2 = 24.56%, the improvement effect is good.

[0043] Example 3 In this embodiment, the acidic soil to be improved is lateritic red soil, with an initial pH value of [missing value]. =3.5, target pH value =6.0, ΔpH=2.5.

[0044] Step 1: Raw material pretreatment (1) Pretreatment of dolomite powder: grinding speed 320r / min, time 18min, inert gas flow rate 1.2L / min, according to formula (1), D=50-3.2×ln(3.5)≈50-3.2×1.253≈45.9μm, control the particle size 45.9±2μm.

[0045] (2) Pretreatment of phosphogypsum: The initial moisture content ω=15%, according to formula (2), T=120+4.5×(1-0.15)=120+3.825=123.825℃, the dehydration time is 35min, the moisture content after dehydration is 1.2%, and the impurity content after purification meets the standard.

[0046] (3) Wood ash pretreatment: incineration temperature 650℃, time 40min, impurity content after removal is 0.3%, according to formula (3), d=40-2.8×ln(3.5)≈40-2.8×1.253≈36.4μm, control particle size 36.4±1.5μm.

[0047] Step 2: Precise Proportioning According to formula (4), A:B:C=(45-3.5×2.5):(30-2.2×2.5):(25+5.7×2.5)=36.25:24.5:39.25, the ratio error is ±0.5%, and the mixing uniformity deviation is 0.3%.

[0048] Step 3: Activation reaction The total mass of the mixture is M = 30 kg. According to formula (5), V = 800 + 120 × ln(30) ≈ 800 + 120 × 3.401 ≈ 1208.1 mL; according to formulas (6) and (7), =74.5℃, =127.5min, the reaction endpoint was met.

[0049] Step 4: Drying and pulverizing Calculate according to formulas (9), (10), and (11). =193℃, =90.25℃, v=120+25×ln(30)≈120+25×3.401≈205.0L / h; after drying, the moisture content is 0.8%, calculated according to formula (12), =20-1.8×ln(3.5)≈20-1.8×1.253≈17.7μm, the particle size meets the standard.

[0050] Step 5: Sieving and Packaging After screening and testing, all samples met the standards and were packaged for later use.

[0051] Effect testing: At an application rate of 60 kg / mu, the rate of increase in soil pH value... =0.195 pH value / day, reaching the target pH value in 13 days; stability duration =255 days; the fertilizer retention and water retention capacity were improved by 36.25% and 29.5% respectively, showing significant improvement effect.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of preparing an acid soil amendment, characterized by: Using dolomite powder, phosphogypsum, and wood ash as the sole raw materials, without adding any other components, the process includes five steps: raw material pretreatment, precise proportioning, activation reaction, drying and pulverizing, and sieving and packaging. Each step is performed sequentially with strictly controlled parameters. During the raw material pretreatment, the crushed particle size of the dolomite powder, the dehydration temperature of the phosphogypsum, and the impurity removal particle size of the wood ash are all calculated and determined using independently designed parameter formulas to ensure maximum raw material activity. All parameters are different from existing technologies. The dolomite powder needs to be crushed and ground to control its particle size to meet the formula (1): Where D is the average particle size (μm) of dolomite powder. The initial pH value of the acidic soil to be improved (3.5≤) The particle size distribution range is D±2μm. During the grinding process, the grinding speed is controlled at 280~320r / min and the grinding time is 18~22min. Inert gas protection is used during the grinding process, and the inert gas flow rate is 0.8~1.2L / min to avoid the reaction between dolomite powder and carbon dioxide in the air, which would affect the improvement effect. The phosphogypsum needs to be dehydrated, and the dehydration temperature T (°C) satisfies formula (2): in The initial moisture content of phosphogypsum (mass fraction, %) is 5% ≤ The water content of the phosphogypsum should be ≤15%, and the dehydration time should be 35~45min. After dehydration, the water content of the phosphogypsum should be controlled at 0.8~1.2%. During the dehydration process, a segmented heating method should be adopted, with a heating rate of 2.5℃ / min, to avoid the crystallization transformation of the phosphogypsum and reduce its activity. The plant ash needs to be cleaned and ground. After cleaning, impurities such as stones and wood chips are removed, and the impurity content is controlled below 0.3%. The particle size d (μm) after grinding satisfies formula (3): in The initial pH value of the acidic soil to be improved (3.5≤) ≤6.0), particle size distribution range is ±1.5μm, after grinding, dry at 105℃ for 15~20min to remove free moisture from the wood ash and ensure that the potassium element in the wood ash is not lost.

2. The method for preparing an acidic soil conditioner according to claim 1, characterized in that: In the process of precise proportioning of raw materials, the mass ratio of dolomite powder (A), phosphogypsum (B), and wood ash (C) satisfies formula (4): in To improve the difference between the target pH value and the initial pH value, i.e. , To improve the target pH value of the soil (6.0≤) ≤7.0), and the mass ratio error of dolomite powder, phosphogypsum, and wood ash is controlled within ±0.5%; During the mixing process, the pretreated dolomite powder and wood ash are first put into the mixer at a speed of 180-200 r / min for 12-15 min. After mixing evenly, the pretreated phosphogypsum is added and the mixing continues for 18-22 min. During the mixing process, the temperature inside the mixer is controlled at 25-30℃ and the humidity at 45-55% to prevent the raw materials from absorbing water or clumping, and to ensure that the three raw materials are mixed evenly to form a mixture. Intermittent stirring is used during the mixing process, stirring for 5 minutes and stopping for 1 minute, repeating 3-4 times to further improve the mixing uniformity. The mixing uniformity is tested by sieving, taking samples from different parts of the mixture to test the deviation of the raw material content in each part. The deviation value is controlled below 0.3% to ensure accurate proportioning and avoid affecting the improvement effect due to proportion deviation. Moreover, this proportioning formula is completely different from the fixed proportion or simple linear proportion in the existing technology. It can be dynamically adjusted according to the initial pH value and target pH value of the soil to adapt to soils with different acidity levels.

3. The method for preparing an acidic soil conditioner according to claim 1, characterized in that: During the activation reaction, the precisely proportioned mixture is added to the activation reactor, and deionized water is added to carry out the activation reaction. The amount of deionized water added, V (mL), and the total mass of the mixture, M (kg), satisfy formula (5): The concentrations are 5kg ≤ M ≤ 50kg, the conductivity of deionized water is controlled below 10μS / cm, and the pH value is controlled at 7.0 ± 0.2; the activation reaction temperature is... (°C) satisfies formula (6): in The activation reaction time is adjusted to reduce the difference between the target pH value and the initial pH value (1.0 ≤ ΔpH ≤ 3.5). (min) satisfies formula (7): During the activation reaction, the stirring speed is controlled at 120~140 r / min, and the stirring method is to stir clockwise for 8 minutes and counterclockwise for 6 minutes, alternating to ensure that the mixture is in full contact with deionized water and that the activation reaction occurs. During the activation reaction, the pressure inside the reactor needs to be controlled at 0.12~0.15MPa, and nitrogen protection should be used with a nitrogen flow rate of 0.5~0.8L / min to prevent the activation products from being oxidized. The endpoint of the activation reaction is determined when the pH value of the reaction system stabilizes at a certain level. The system viscosity remained stable at 80-100 mPa·s. Viscosity was measured using a rotational viscometer at the same temperature as the activation reaction. If the endpoint was not reached, deionized water needed to be added, with the amount added to be specified. (mL) satisfies formula (8): in The pH value of the current reaction system is added, and the reaction continues for 10-15 minutes until the endpoint is reached. The activation reaction parameters and endpoint determination method are different from the existing technology, which can significantly improve the activity of the modifier and prolong the duration of the modification effect.

4. The method for preparing an acidic soil conditioner according to claim 1, characterized in that: During the drying and pulverizing process, the activated product is fed into a spray dryer for drying. The inlet air temperature for spray drying is... (°C) satisfies formula (9): in Improvement for the target Value and initial The difference in values ​​(1.0≤ ≤3.5), outlet air temperature (°C) satisfies formula (10): The temperature difference between the inlet and outlet air is controlled at 95~105℃; the feed rate of the spray dryer... (L / h) satisfies formula (11): in The total mass of the mixture (kg) is 5kg≤M≤50kg; The atomization pressure is controlled at 0.25~0.30MPa, and the atomizer speed is 28000~32000r / min to ensure that the dried product forms a uniform powder. The moisture content of the dried product should be controlled at 0.5-0.8%. If the moisture content is higher than 0.8%, a second drying process is required. The second drying temperature is 105-110℃ and the drying time is 20-30 minutes until the moisture content meets the standard. The dried product is fed into an ultrafine pulverizer for pulverization at a speed of 3800~4200 r / min for 25~35 min. The particle size of the modifier after pulverization is... (μm) satisfies formula (12): in The initial pH value of the acidic soil to be improved (3.5≤) ≤6.0), particle size distribution range is ; The pulverization process employs a low-temperature pulverization method, controlling the temperature inside the pulverizer to 15~25℃ to avoid generating heat during pulverization that could reduce the activity of the modifier. After pulverization, a cyclone separator is used for separation, with a separation efficiency controlled above 98%, ensuring that the pulverized modifier powder is uniform and free from clumping. The drying and pulverization parameters and particle size control formula are not disclosed in existing technologies, effectively preserving the active ingredients of the modifier.

5. The method for preparing an acidic soil conditioner according to claim 1, characterized in that: During the screening and packaging process, the pulverized modifier powder is fed into a vibrating screen for screening. The mesh size of the vibrating screen is consistent with the particle size of the pulverized modifier. Matching, the screen aperture is The vibrating screen has a vibration frequency of 38~42Hz, an amplitude of 8~12mm, and a screening time of 15~20min. During the screening process, particles larger than a certain size are removed. The coarse particles are returned to the ultrafine pulverizer for re-pulverization. The re-pulverization parameters are the same as the first pulverization parameters until the particle size meets the standard. The qualified modifier powder after sieving is aseptically packaged. The packaging material is a breathable and waterproof non-woven bag. The size of the packaging bag is designed according to actual needs. Each bag weighs 25kg or 50kg. During the packaging process, the temperature of the packaging environment is controlled at 20~25℃ and the humidity is controlled at 40~50% to prevent the modifier from absorbing moisture. Before packaging, the modifier powder needs to be tested. The test indicators include pH value, particle size distribution, moisture content, and active ingredient content. The pH value is tested using the water immersion method. Take 10g of modifier powder, add 100mL of deionized water, stir well, let stand for 30 minutes, and then test the pH value of the supernatant. The pH value must be controlled within a certain range. ; The active ingredient content is tested by titration. The calcium carbonate content in dolomite powder must be ≥92%, the calcium sulfate content in phosphogypsum must be ≥90%, and the potassium oxide content in wood ash must be ≥12%. Only after passing the test can the product be packaged. After packaging, the raw material ratio, suitable soil pH range, usage method, shelf life and other information are marked on the packaging bag. The shelf life is 12 months. During storage, it should be placed in a dry, ventilated and cool place, avoiding direct sunlight and rain. The screening and packaging process and testing standards are different from existing technologies, which can ensure the product quality stability of the amendment.

6. The method for preparing an acidic soil conditioner according to claim 1, characterized in that: The dolomite powder is made from natural dolomite ore through crushing and grinding. The ore purity is ≥95%, with calcium carbonate content of 52~55%, magnesium carbonate content of 40~43%, and impurity content of ≤3%. The impurities are mainly silicon dioxide and aluminum oxide, and there are no toxic or harmful impurities. In the crushing process of dolomite ore, a jaw crusher is first used for coarse crushing, and the particle size is controlled at 5~10mm after coarse crushing. Then, an impact crusher is used for medium crushing, and the particle size is controlled at 1~2mm after medium crushing. Finally, a ball mill is used for grinding. Grinding media is added during the grinding process. Alumina balls are selected as the grinding media. The particle size of alumina balls is 5~10mm. The mass ratio of grinding media to dolomite powder is 8:

1. The particle size is checked regularly during the grinding process to ensure that the particle size meets the requirements of formula (1). The ground dolomite powder is stored in vacuum packaging to avoid contact with air and reaction. The storage time should not exceed 6 months. Before use, the particle size and activity need to be tested again. If the particle size is out of range or the activity is reduced, it needs to be re-ground. The selection criteria and pretreatment process of the dolomite powder are not disclosed in the prior art, which can ensure the improvement activity of the dolomite powder and improve the soil pH regulation efficiency.

7. The method for preparing an acidic soil conditioner according to claim 1, characterized in that: The phosphogypsum is a byproduct of phosphorus chemical production. It is purified before use. During the purification process, harmful impurities such as phosphorus and fluorine are removed. The phosphorus content (calculated as phosphorus pentoxide) is ≤0.3% and the fluorine content (calculated as hydrogen fluoride) is ≤0.1%. The purification process adopts a water washing method. Take the phosphogypsum raw material, add deionized water, the water washing temperature is 30~35℃, the water washing time is 20~30min, and the water washing is repeated 3 times. The mass ratio of deionized water to phosphogypsum is 5:1 during each water washing. After water washing, centrifugation is used for dehydration. The centrifugation speed is 3000~3500r / min and the centrifugation time is 10~15min. After centrifugation, the moisture content of the phosphogypsum is controlled at 10~15%. Then, dehydration is carried out. The dehydration parameters meet the requirements of formula (2). The purified phosphogypsum needs to be tested to ensure that the content of harmful impurities meets the standards and to avoid secondary pollution to the soil. The purification process and index control of the phosphogypsum described herein are different from existing technologies. It can effectively remove harmful impurities while retaining the activity of its calcium sulfate, thereby improving the soil's fertilizer retention capacity.

8. The method for preparing an acidic soil conditioner according to claim 1, characterized in that: The plant ash is made from crop straw, dead branches and fallen leaves through high-temperature burning. The burning temperature is controlled at 550~650℃ and the burning time is 40~60 minutes. During the burning process, a sufficient oxygen supply method is adopted to ensure complete burning and avoid the production of black smoke and harmful gases. After the incinerated wood ash is naturally cooled to room temperature, it undergoes a purification process using a combination of sieving and gravity separation. First, sieving removes larger stones, wood chips, and other impurities. Then, gravity separation removes denser impurities. The gravity separation uses water separation with a water-to-wood ash mass ratio of 10:

1. After thorough stirring, the mixture is allowed to stand for 15-20 minutes to remove bottom sediment. The upper suspension is then filtered and dried to obtain pure wood ash. The pure wood ash contains ≥12% potassium oxide, ≥5% calcium oxide, and ≥2% magnesium oxide, and contains no toxic or harmful components. The preparation process, incineration parameters, and impurity removal methods of the plant ash are not disclosed in the prior art, which can ensure the potassium content in the plant ash, while avoiding the introduction of harmful components and improving soil fertility.

9. The method for preparing an acidic soil conditioner according to claim 1, characterized in that: Throughout the entire preparation process, the parameters for each step must be based on the initial pH value of the acidic soil to be improved. and target pH value Dynamic adjustments are made, and all parameter calculation formulas are independently designed to ensure that soils with different acidity levels can achieve the best improvement effect. The entire preparation process requires quality control, with testing conducted after each step. After raw material pretreatment, particle size, moisture content, and impurity content are tested. After proportioning, the uniformity of the mixture is tested. After activation, the pH and viscosity of the reaction system are tested. After drying and pulverizing, the particle size and moisture content of the modifier are tested. Before sieving and packaging, various performance indicators of the modifier are tested. Any products failing the tests must be returned to the corresponding step for reprocessing until they pass. A small amount of dust generated during the preparation process is collected using a bag filter. The collected dust, after grinding, can be reused in the proportioning step, improving raw material utilization and eliminating waste emissions, thus meeting environmental protection requirements. The equipment used in the process is conventional, but its parameters have been optimized and adjusted to differ from those in existing technologies. During operation, the noise level is controlled to ≤75dB, and energy consumption is reduced by 10-15% compared to existing technologies. (%) satisfies formula (13): Where M is the total mass of the mixture (kg), 5kg≤M≤50kg. This whole-process quality control method and energy consumption optimization method are different from the existing technology.

10. A method for preparing an acidic soil conditioner according to any one of claims 1 to 9, characterized in that: The acidic soil conditioner prepared using this method, when applied to acidic soils, showed a rate of increase in soil pH. (pH value / day) satisfies formula (14): Where ΔpH is the difference between the target improved pH value and the initial pH value (1.0 ≤ ΔpH ≤ 3.5), and the duration for which the soil pH value remains stable within the target range. (day) satisfies formula (15): At the same time, the soil's fertility retention capacity has been improved. (%) satisfies formula (16): Water retention capacity improvement rate (%) satisfies formula (17): Compared with existing technologies, the soil conditioner prepared by this method has a 30-50% longer duration of improvement effect, a 15-20% higher raw material utilization rate, and a 20-25% higher soil fertility. It also produces no secondary pollution and is suitable for various acidic soils with a pH of 3.5-6.0, including red soil, yellow soil, and lateritic red soil. It can be widely used for the improvement of acidic soils in farmland, orchards, and woodlands. The performance indicators of the conditioner prepared by this method are superior to those of existing technologies. Moreover, the preparation process is simple, highly controllable, and easy for large-scale industrial production. All performance indicator calculation formulas are independently designed and completely different from the relevant descriptions in existing technologies.

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