Medium-trace granular fertilizer prepared from phosphate tailings and preparation method of medium-trace granular fertilizer

Abstract

The invention relates to a medium-trace granular fertilizer prepared from phosphate tailings and a preparation method, the medium-trace granular fertilizer prepared from phosphate tailings comprises 68-94.8 parts of phosphate tailings, 3-10 parts of a strengthening auxiliary agent, 1-10 parts of a binder, 1-10 parts of an activating auxiliary agent and 0.2-2 parts of a micronutrient element material, and a penetrant aqueous solution is based on 100 parts of the above components. And then adding 4-10 parts of a penetrant aqueous solution. A preparation method; the method comprises the following steps: drying the phosphate tailings, ball-milling and crushing to 100-200 meshes; the preparation method comprises the following steps: mixing a micronutrient element material, a binder, an activating auxiliary agent and a strengthening auxiliary agent, and crushing to 100-200 meshes to obtain a synergist; the phosphate tailing powder and a synergist are mixed and put into a granulator, a penetrant aqueous solution with the mass concentration of 0.1-5% is sprayed according to the proportion, granulation, screening and drying are conducted, and the medium-trace granular fertilizer prepared from the 3-5 mm phosphate tailings is obtained. By adding the penetrant, the requirement on the composition of the phosphate tailings is greatly reduced, so that the medium-trace granular fertilizer prepared from the phosphate tailings has better dissolvability, the preparation cost is low, and the medium-trace granular fertilizer can be applied to large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of waste resource recycling and the preparation of medium and trace element fertilizers, and more specifically to medium and trace element granular fertilizers prepared from phosphorous chemical by-products, phosphorous tailings, and a preparation method thereof. Background Art

[0002] In the current status of agricultural fertilization, the excessive use of macronutrient fertilizers such as nitrogen, phosphorus, and potassium has led to soil nutrient imbalance, and the problem of insufficient application of medium and trace element fertilizers has become increasingly prominent. According to investigations, about 85% of the cultivated land in China is severely lacking in medium and trace elements, and the lack of elements such as calcium, magnesium, sulfur, boron, and zinc is relatively common. Phosphorous tailings, as by-products of the phosphorous chemical industry, are inexpensive and mainly composed of metal oxides such as dolomite (CaMg(CO3)2), magnesium oxide (MgO), and silicon dioxide (SiO2), which can meet the needs of plants for essential nutrient elements such as calcium, magnesium, phosphorus, and silicon for growth.

[0003] However, phosphorous tailings are sandy in texture and difficult to granulate. Their calcium and magnesium nutrients mainly exist in the form of carbonates, which are difficult for plants to absorb. These have all become bottlenecks for directly using phosphorous tailings as fertilizers. Therefore, it is necessary to be easy to granulate and facilitate mechanized operation. At the same time, it is required that the fertilizer granules quickly disintegrate into powder in the soil, expand the contact area with the soil, and improve the absorption efficiency of plants.

[0004] With the continuous development of the phosphorous chemical industry, the cumulative amount of phosphorous tailings is increasing. Only in Hubei Province, the annual new discharge of phosphorous tailings reaches 3 million tons, and the stockpile of phosphorous tailings exceeds 30 million tons. However, due to different sources of raw ore, the composition and properties of phosphorous tailings vary greatly. The present invention conducts experiments and tests on phosphorous tailings from more than a dozen different manufacturers in Hubei Province and finds that some phosphorous tailings with a grayish-black color have good disintegration effects without any treatment with disintegrants, while phosphorous tailings with a yellowish color generally have difficulty in disintegration, which is due to the differences in the content of organic matter and transition metal ions in the phosphate ore. However, since phosphorous tailings are generally used as industrial waste, it is difficult to require the stability of the composition of phosphorous tailings.

[0005] Application No. CN202411023638.7 discloses an acidolysis phosphorous tailing granule, a preparation method thereof, and an application. It mainly uses slag acid as an activator to react with phosphorous tailings to improve the viscosity of phosphorous tailings, and uses cellulose as a disintegrant for granulation. In this way, the dosage of slag acid is relatively high, and the acid corrosion resistance requirements for the materials of granulation equipment are relatively high. In addition, slag acid contains a large amount of harmful substances such as fluorine, aluminum, and heavy metal elements. Therefore, this method is not conducive to large-scale application in agriculture, and the disintegration effect of fertilizer granules is not mentioned in this method.

[0006] Application No. CN202411013654.8 discloses a method for granulating phosphorus tailings, the phosphorus tailings particles prepared thereby, and applications thereof. Specifically, a composite binder is obtained by uniformly mixing tannic acid, lignosulfonate, and saponin, and then the composite binder is compounded with phosphorus tailings and granulated by a disk granulator with water. In this solution, both tannic acid and saponin in the composite binder are substances with relatively high costs, which is not conducive to large-scale applications. At the same time, this method can make the fertilizer have good dispersibility only by using a binder, without considering the situation that some phosphorus tailings themselves have good viscosity, are easy to granulate, and difficult to disintegrate.

[0007] Application No. CN202411238861.3 discloses a method for preparing a slow-release medium and trace element fertilizer by acidolysis of phosphorus tailings with low-quality phosphoric acid. The method mainly involves mixing phosphorus tailings and low-grade phosphoric acid and then granulating, without mentioning the disintegration effect of the prepared fertilizer particles.

[0008] Application No. CN201810687284.4 discloses a granular medium and trace nutrient fertilizer and its production method. Specifically, sandy material yellow phosphorus slag is prepared into particles through a binder, and the viscous substance components include polyacrylamide, polyvinyl alcohol, modified starch, magnesium sulfate, aminosulfonate, or calcium lignosulfonate. The high-cost polymer has a relatively high cost, and although yellow phosphorus slag and phosphorus tailings are both sandy materials, there are significant differences in physical and chemical properties, and the disintegration effect of the fertilizer particles is not mentioned.

[0009] Application No. CN202311514018.9 discloses a method for the resource utilization of high-calcium and magnesium phosphorus tailings, in which surfactants are used to promote the extraction of effective nutrients, without mentioning the effect of surfactants on the disintegration of medium and trace element granular fertilizers mainly made of phosphorus tailings.

[0010] Therefore, how to invent a method for medium and trace element granular fertilizers mainly made of phosphorus tailings with low cost and easy disintegration has become an urgent problem to be solved. Summary of the Invention

[0011] The purpose of the present invention is to provide a medium and trace element granular fertilizer prepared from phosphorus tailings and a preparation method thereof, which is used to solve the problems that phosphorus tailings are difficult to granulate and disintegrate. The medium and trace element granular fertilizer prepared from phosphorus tailings has the characteristics of low cost, high strength, and rapid dispersion.

[0012] The technical solution adopted by the present invention is as follows:

[0013] A medium and trace element granular fertilizer prepared from phosphorus tailings. By weight, the components are characterized in that the composition of the medium and trace element granular fertilizer prepared from phosphorus tailings is as follows: 68 - 94.8 parts of phosphorus tailings, 3 - 10 parts of strengthening aid, 1 - 10 parts of binder, 1 - 10 parts of activation aid, 0.2 - 2 parts of trace nutrient element material. Based on 100 parts of the total amount of the above components, 4 - 10 parts of penetrant aqueous solution are added.

[0014] The strengthening aid is one or a mixture of magnesium oxide and magnesium sulfate.

[0015] The binder is one or a mixture of bentonite and kaolin.

[0016] The activation aid is one or a mixture of humic acid, fulvic acid, lignite, or more than two of them.

[0017] The trace nutrient element material is one or a mixture of zinc oxide and boron oxide.

[0018] The penetrant aqueous solution is a surfactant or an organic solvent aqueous solution with a mass concentration of 0.1 - 5%.

[0019] The surfactant is a non - ionic surfactant or an anionic surfactant. Among them, the non - ionic surfactant is fatty alcohol polyoxyethylene ether, and the anionic surfactant is sodium dodecylbenzenesulfonate or sodium dioctyl sulfosuccinate.

[0020] The organic solvent is ethanol or ethylene glycol.

[0021] A method for preparing a medium and trace element granular fertilizer from phosphorus tailings, which is characterized by including the following steps:

[0022] Step 1: Dry the phosphorus tailings and crush them to 100 - 200 meshes using a ball mill to obtain phosphorus tailings powder.

[0023] Step 2: Mix and crush the trace nutrient element material, binder, activation aid, and strengthening aid to 100 - 200 meshes to obtain a synergist.

[0024] Step 3: Prepare a penetrant aqueous solution with a mass concentration of 0.1 - 5% of the penetrant.

[0025] Step 4: Mix the phosphorus tailings powder from Step 1 and the synergist from Step 2 in proportion, put them into a granulator, spray the penetrant aqueous solution in proportion for granulation, screening, and drying to obtain a 3 - 5 mm medium and trace element granular fertilizer prepared from phosphorus tailings.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The addition of the penetrant significantly reduces the requirements for the composition of phosphate tailings, can adapt to most phosphate tailings, enables the medium and trace element granular fertilizers prepared from phosphate tailings to have good dispersibility, and reduces the component limitations on the raw material phosphate tailings.

[0028] 2. Both the binder and the activation assistant are common natural components, with low prices and no pollution.

[0029] 3. The medium and trace element granular fertilizer prepared from phosphate tailings in the present invention has the advantages of comprehensive nutrients, good strength, and easy dispersibility. Its good granulation property and low preparation cost can be applied to large-scale industrial production. Specific Embodiments

[0030] The present invention will be further described in combination with embodiments.

[0031] Example 1

[0032] The composition of a medium and trace element granular fertilizer prepared from phosphate tailings is as follows: 840 kg of phosphate tailings powder, 50 kg of magnesium oxide, 50 kg of bentonite, 50 kg of humic acid, 10 kg of zinc oxide, and 100 kg of an aqueous solution of fatty alcohol polyoxyethylene ether with a mass concentration of 0.5%; the preparation method is carried out according to the following steps:

[0033] Step 1: Dry the phosphate tailings and crush them using a ball mill to obtain phosphate tailings powder with a mesh size of 200.

[0034] Step 2: Mix and crush 50 kg of magnesium oxide, 50 kg of bentonite, 50 kg of humic acid, and 10 kg of zinc oxide to obtain a synergist with a mesh size of 100.

[0035] Step 3: Prepare an aqueous solution of fatty alcohol polyoxyethylene ether with a mass concentration of 0.5%.

[0036] Step 4: Mix 840 kg of phosphate tailings powder and 160 kg of synergist powder, then feed them into a rotary drum granulator, and spray 100 kg of an aqueous solution of fatty alcohol polyoxyethylene ether with a mass concentration of 0.5% in batches for granulation, screening, and drying to obtain a medium and trace element granular fertilizer product prepared from phosphate tailings with a particle size of 3 - 5 mm, denoted as P1.

[0037] Example 2

[0038] The composition of a medium and trace element granular fertilizer prepared from phosphate tailings is as follows: 8000 kg of phosphate tailings powder, 1000 kg of magnesium sulfate, 600 kg of bentonite, 200 kg of humic acid, 200 kg of boron oxide, and 600 kg of an aqueous solution of sodium dioctyl sulfosuccinate with a mass concentration of 0.1%; the preparation method is carried out according to the following steps:

[0039] Step 1: Dry the phosphate tailings and crush them using a ball mill to obtain phosphate tailings powder with a mesh size of 200.

[0040] Step 2: Mix 1000 kg of magnesium sulfate, 600 kg of bentonite, 200 kg of humic acid, and 200 kg of boron oxide, and then pulverize them to obtain a synergist with a mesh size of 100;

[0041] Step 3: Prepare an aqueous solution of sodium dioctyl sulfosuccinate with a mass concentration of 0.1%;

[0042] Step 4: Mix 8000 kg of phosphorus tailings powder and 2000 kg of synergist powder, then feed them into a drum granulator, and spray 600 kg of the aqueous solution of sodium dioctyl sulfosuccinate with a mass concentration of 0.1% in batches for granulation, screening, and drying to obtain a medium and trace element granular fertilizer product prepared from 3 - 5 mm phosphorus tailings, denoted as P2.

[0043] Example 3

[0044] The composition of a medium and trace element granular fertilizer prepared from phosphorus tailings is as follows: 84 kg of phosphorus tailings powder, 3 kg of magnesium oxide, 6 kg of kaolin, 5 kg of humic acid, 2 kg of boron oxide, and 6 kg of an aqueous solution of sodium dodecylbenzenesulfonate with a mass concentration of 3%. The preparation method is carried out according to the following steps:

[0045] Step 1: Dry the phosphorus tailings and pulverize them using a ball mill to obtain phosphorus tailings powder with a mesh size of 200;

[0046] Step 2: Mix 3 kg of magnesium oxide, 6 kg of kaolin, 5 kg of humic acid, and 2 kg of boron oxide, and then pulverize them to obtain a synergist with a mesh size of 200;

[0047] Step 3: Prepare an aqueous solution of sodium dodecylbenzenesulfonate with a mass concentration of 3%;

[0048] Step 4: Mix 84 kg of phosphorus tailings powder and 16 kg of synergist powder, then feed them into a drum granulator, and spray 6 kg of the aqueous solution of sodium dodecylbenzenesulfonate in batches for granulation, screening, and drying to obtain a medium and trace element granular fertilizer product prepared from 3 - 5 mm phosphorus tailings, denoted as P3.

[0049] Example 4

[0050] The composition of a medium and trace element granular fertilizer prepared from phosphorus tailings is as follows: 768 kg of phosphorus tailings powder, 80 kg of magnesium sulfate, 100 kg of kaolin, 50 kg of lignite, 2 kg of zinc oxide, and 80 kg of an aqueous solution of ethylene glycol with a mass concentration of 5%. The preparation method is carried out according to the following steps:

[0051] Step 1: Dry the phosphorus tailings and pulverize them using a ball mill to obtain phosphorus tailings powder with a mesh size of 150;

[0052] Step 2: 80 kg of magnesium sulfate, 100 kg of kaolin, 50 kg of lignite, and 2 kg of zinc oxide were mixed and crushed to obtain a 150-mesh synergist;

[0053] Step 3, preparing an ethylene glycol aqueous solution with a mass concentration of 5%;

[0054] Step 4: 768 kg of phosphate tailings powder and 232 kg of synergist powder are mixed and fed into a rotary drum granulator. 80 kg of 5% ethylene glycol aqueous solution is sprayed in batches for granulation, screening, and drying to obtain a medium-micro granular fertilizer product prepared from 3-5 mm phosphate tailings, which is recorded as P4.

[0055] Example 5

[0056] A medium-micro granular fertilizer prepared from phosphate tailings comprises: 80 tons of phosphate tailings powder, 10 tons of magnesium oxide, 6 tons of bentonite, 2 tons of lignite, 1 t of zinc oxide, 1 t of boron oxide, and 8 tons of a 1% fatty alcohol polyoxyethylene ether aqueous solution. The preparation method is carried out according to the following steps:

[0057] Step 1: drying the phosphate tailings and crushing them using a ball mill to obtain 100-mesh phosphate tailings powder;

[0058] Step 2: 10 t of magnesium oxide, 6 t of bentonite, 2 t of lignite, 1 t of zinc oxide, and 1 t of boron oxide were mixed and crushed to obtain a 100-mesh synergist;

[0059] Step 3, preparing a fatty alcohol polyoxyethylene ether aqueous solution with a mass concentration of 1%;

[0060] Step 4: 80t of phosphate tailings powder and 20t of synergist powder are mixed and fed into a rotary drum granulator. 8t of 1% fatty alcohol polyoxyethylene ether aqueous solution are sprayed in batches for granulation, screening, and drying to obtain a medium-to-trace granular fertilizer product prepared from phosphate tailings with a size of 3-5mm, which is recorded as P5.

[0061] Example 6

[0062] A medium-micro granular fertilizer prepared from phosphate tailings comprises: 83 tons of phosphate tailings powder, 5 tons of magnesium oxide, 5 tons of kaolin, 5 tons of fulvic acid, 1 t of zinc oxide, 1 t of boron oxide, and 7 tons of 0.5% ethanol aqueous solution. The preparation method is carried out according to the following steps:

[0063] Step 1: drying the phosphate tailings and crushing them using a ball mill to obtain 100-mesh phosphate tailings powder;

[0064] Step 2: 5t of magnesium oxide, 5t of kaolin, 5t of fulvic acid, 1t of zinc oxide, and 1t of boron oxide were mixed and crushed to obtain a 100-mesh synergist;

[0065] Step 3: Prepare an aqueous ethanol solution with a mass concentration of 0.5%.

[0066] Step 4: Mix 83 t of phosphorus tailings powder and 17 t of synergist powder, then feed them into a drum granulator, and spray 7 t of the aqueous ethanol solution with a mass concentration of 0.5% in batches for granulation, screening, and drying to obtain a medium and trace element granular fertilizer product prepared from 3 - 5 mm phosphorus tailings, denoted as P6.

[0067] Example 7

[0068] The composition of a medium and trace element granular fertilizer prepared from phosphorus tailings is as follows: 68 kg of phosphorus tailings powder, 10 kg of magnesium oxide, 10 kg of bentonite, 10 kg of humic acid, 2 kg of boron oxide, and 4 kg of an aqueous solution of sodium dodecylbenzenesulfonate with a mass concentration of 3%; the preparation method is carried out according to the following steps:

[0069] Step 1: Dry the phosphorus tailings and crush them using a ball mill to obtain phosphorus tailings powder with a mesh size of 100.

[0070] Step 2: Mix and crush 10 kg of magnesium oxide, 10 kg of bentonite, 10 kg of humic acid, and 2 kg of boron oxide to obtain a synergist with a mesh size of 100.

[0071] Step 3: Prepare an aqueous solution of sodium dodecylbenzenesulfonate with a mass concentration of 3%.

[0072] Step 4: Mix 80 kg of phosphorus tailings powder and 20 kg of synergist powder, then feed them into a drum granulator, and spray 4 kg of the aqueous solution of sodium dodecylbenzenesulfonate with a mass concentration of 3% in batches for granulation, screening, and drying to obtain a medium and trace element granular fertilizer product prepared from 3 - 5 mm phosphorus tailings, denoted as P7.

[0073] Example 8

[0074] The composition of a medium and trace element granular fertilizer prepared from phosphorus tailings is as follows: 948 kg of phosphorus tailings powder, 30 kg of magnesium sulfate, 10 kg of bentonite, 10 kg of humic acid, 2 kg of boron oxide, and 40 kg of an aqueous solution of sodium dioctyl sulfosuccinate with a mass concentration of 1%; the preparation method is carried out according to the following steps:

[0075] Step 1: Dry the phosphorus tailings and crush them using a ball mill to obtain phosphorus tailings powder with a mesh size of 200.

[0076] Step 2: Mix and crush 30 kg of magnesium sulfate, 10 kg of bentonite, 10 kg of humic acid, and 2 kg of boron oxide to obtain a synergist with a mesh size of 100.

[0077] Step 3: Prepare an aqueous solution of sodium dioctyl sulfosuccinate with a mass concentration of 1%

[0078] Step 4: Mix 948 kg of phosphorus tailings powder and 52 kg of synergist powder, then feed the mixture into a drum granulator, and spray 40 kg of an aqueous solution of sodium dioctyl sulfosuccinate with a mass concentration of 1% in batches for granulation, screening, and drying to obtain a medium and trace element granular fertilizer product prepared from 3 - 5 mm phosphorus tailings, denoted as P8.

[0079] Comparative Example 1

[0080] The composition of a medium and trace element granular fertilizer prepared from phosphorus tailings is as follows: 840 kg of phosphorus tailings powder, 50 kg of magnesium oxide, 50 kg of bentonite, 50 kg of humic acid, and 10 kg of zinc oxide; the preparation method is carried out according to the following steps:

[0081] Step 1: Dry the phosphorus tailings and crush them using a ball mill to obtain phosphorus tailings powder with a mesh size of 200. <{

[0082] Step 2: Mix and crush 50 kg of magnesium oxide, 50 kg of bentonite, 50 kg of humic acid, and 10 kg of zinc oxide to obtain a synergist with a mesh size of 100.

[0083] Step 3: Mix 840 kg of phosphorus tailings powder and 160 kg of synergist powder, then feed the mixture into a drum granulator, and spray 100 kg of water in batches for granulation, screening, and drying to obtain a medium and trace element granular fertilizer product prepared from 3 - 5 mm phosphorus tailings, denoted as W1.

[0084] Comparative Example 2

[0085] The composition of a medium and trace element granular fertilizer prepared from phosphorus tailings is as follows: 8000 kg of phosphorus tailings powder, 1000 kg of magnesium sulfate, 600 kg of bentonite, 200 kg of humic acid, and 200 kg of boron oxide; the preparation method is carried out according to the following steps:

[0086] Step 1: Dry the phosphorus tailings and crush them using a ball mill to obtain phosphorus tailings powder with a mesh size of 200.

[0087] Step 2: Mix and crush 1000 kg of magnesium sulfate, 600 kg of bentonite, 200 kg of humic acid, and 200 kg of boron oxide to obtain a synergist with a mesh size of 100.

[0088] Step 3: Mix 8000 kg of phosphorus tailings powder and 2000 kg of synergist powder, then feed the mixture into a drum granulator, and spray 600 kg of water in batches for granulation, screening, and drying to obtain a medium and trace element granular fertilizer product prepared from 3 - 5 mm phosphorus tailings, denoted as W2.

[0089] Comparative Example 3

[0090] The composition of a medium- and micro-element granular fertilizer prepared from phosphorus tailings is as follows: 84 kg of phosphorus tailings powder, 3 kg of magnesium oxide, 6 kg of kaolin, 5 kg of humic acid, and 2 kg of boron oxide; the preparation method is carried out according to the following steps:

[0091] Step 1: Dry the phosphorus tailings and crush them using a ball mill to obtain phosphorus tailings powder with a mesh size of 200.

[0092] Step 2: Mix and crush 3 kg of magnesium oxide, 6 kg of kaolin, 5 kg of humic acid, and 2 kg of boron oxide to obtain a synergist with a mesh size of 100.

[0093] Step 3: Mix 84 kg of phosphorus tailings powder and 16 kg of synergist powder, then feed them into a drum granulator, and spray 6 kg of water in batches for granulation, screening, and drying to obtain a medium- and micro-element granular fertilizer product prepared from phosphorus tailings with a particle size of 3 - 5 mm, denoted as W3.

[0094] Method for evaluating the performance of granular products:

[0095] Granulation rate: Use a square-hole sieve with a size of 2 mm - 4 mm for screening. Particles with a particle size between 2 mm and 4 mm are qualified products, and the granulation rate is calculated according to formula (1).

[0096] Granulation rate = m1 / m2 * 100% (1)

[0097] In the formula, m1 is the mass of the medium- and micro-element granular fertilizer product prepared from phosphorus tailings with a particle size between 3 mm and 5 mm; m2 is the total mass of the mixed powder materials before granulation.

[0098] Particle strength: Take 30 fertilizers with uniform size and measure them using a KQ-3 type particle strength tester.

[0099] Dissolution rate: Take a certain amount of medium- and micro-element granular fertilizer product prepared from phosphorus tailings, with the mass denoted as m3. Immerse it in still water at room temperature for 10 minutes, weigh the mass of the test sample that does not pass through a 1.00 mm test sieve, with the mass denoted as m4, and the dissolution rate is calculated according to formula (2).

[0100] Dissolution rate = (m3 - m4) / m3 * 100% (2)

[0101] The final test results are shown in Table 1.

[0102] Table 1 Performance of medium- and micro-element granular fertilizer prepared from phosphorus tailings

[0103] Granulation rate % Disintegration rate % Particle strength N Example 1 74 97 18.3 Example 2 68 94 22.6 Example 3 69 90 15.1 Example 4 71 98 17.1 Example 5 74 94 16.5 Example 6 69 96 19.3 Example 7 75 98 18.5 Example 8 77 97 16.9 Comparative Example 1 75 45 20.5 Comparative Example 2 70 40 26.3 Comparative Example 3 65 37 17.9

[0104] From the data in Table 1, it can be seen that the addition of the penetrant has little effect on the granulation of the product, but the particle strength will decrease slightly, and the dissolution rate will increase significantly. This is because the phosphate tailings itself contains some viscous substances, which cannot be dispersed in water, resulting in the particles being unable to disintegrate quickly. However, after adding the penetrant, the viscosity of these phosphate tailings particles can be significantly reduced, thereby greatly increasing the dissolution rate of the particles, but it will also cause a slight decrease in the particle strength.

[0105] Select the above-mentioned examples and comparative examples for bioassay experiments. Select corn seedlings and tomato seedlings as experimental objects, and conduct two groups of treatments respectively. The fertilization amount per plant is shown in Table 2. Observe the effects of corn seedlings and tomato seedlings on plant height, stem diameter, and chlorophyll content 7 days after fertilization. The test results are shown in Table 3.

[0106] Table 2 Bioassay experiment test table

[0107] Treatment Treatment method CK 2g NPK(15 - 15 - 15) Experimental group 1 1g NPK(15 - 15 - 15)+1g P1 Experimental group 2 1g NPK(15 - 15 - 15)+1g P2 Experimental group 3 1g NPK(15 - 15 - 15)+1g P3 Control group 1 1g NPK(15 - 15 - 15)+1g W1 Control group 2 1g NPK(15 - 15 - 15)+1g W2 Control group 3 1g NPK(15 - 15 - 15)+1g W3

[0108] Table 3 Effects of medium and trace element granular fertilizers prepared from phosphate tailings on corn and tomato plants

[0109]

[0110] From the data in Table 3, it can be seen that the simultaneous application of medium and trace elements and nitrogen, phosphorus, and potassium compound fertilizers is better than the application of only nitrogen, phosphorus, and potassium compound fertilizers, which can significantly increase the early biological growth of corn and tomatoes. This is because corn and tomatoes grow rapidly and have strong metabolism during the seedling stage, and have a large demand for various nutrients. Medium and trace elements, as enzyme activators or components, can significantly affect their physiological metabolism process, thereby having an obvious promoting effect on growth. By comparing the three experimental groups and the three control groups, it can be found that due to the addition of the penetrant, the fertilizer particles that are easily disintegrated can release nutrients better to supply the plants and promote plant growth.

Claims

1. A medium and trace element granular fertilizer prepared from phosphorus tailings, characterized in that, by weight, The composition of the medium and trace element granular fertilizer prepared from phosphorus tailings is as follows: 68 - 94.8 parts of phosphorus tailings, 3 - 10 parts of strength enhancing agent, 1 - 10 parts of binder, 1 - 10 parts of activation agent, 0.2 - 2 parts of trace nutrient element material. Based on the total amount of the above components being 100 parts, 4 - 10 parts of penetrant aqueous solution are added.

2. The medium- and micro-element granular fertilizer prepared from phosphorus tailings according to claim 1, characterized in that The strength enhancing agent is one or a mixture of magnesium oxide and magnesium sulfate.

3. The medium- and micro-element granular fertilizer prepared from phosphorus tailings according to claim 1, characterized in that, The binder is one or a mixture of bentonite and kaolin.

4. The medium and trace element granular fertilizer prepared from phosphorus tailings according to claim 1, wherein, The activation agent is one or a mixture of humic acid, fulvic acid, lignite and the like.

5. The medium and trace element granular fertilizer prepared from phosphorus tailings according to claim 1, characterized in that, The trace nutrient element material is one or a mixture of zinc oxide and boron oxide.

6. The medium and trace element granular fertilizer prepared from phosphorus tailings according to claim 1, characterized in that, The penetrant aqueous solution is an aqueous solution of a surfactant or organic solvent with a mass concentration of 0.1 - 5%.

7. The medium and trace element granular fertilizer prepared from phosphorus tailings according to claim 6, characterized in that, The surfactant is a non - ionic surfactant or an anionic surfactant. The non - ionic surfactant is fatty alcohol polyoxyethylene ether, and the anionic surfactant is sodium dodecylbenzenesulfonate or sodium dioctyl sulfosuccinate.

8. The medium and trace element granular fertilizer prepared from phosphorus tailings according to claim 6, characterized in that, The organic solvent is ethanol or ethylene glycol.

9. The method for preparing the medium- and micro-element granular fertilizer from phosphorus tailings according to any one of claims 1-8, characterized in that It includes the following steps: Step 1: Dry the phosphorus tailings and crush them to 100 - 200 mesh using a ball mill to obtain phosphorus tailings powder. Step 2: Mix and crush the trace nutrient element material, binder, activation agent, and strength enhancing agent to 100 - 200 mesh to obtain a synergist. Step 3: Prepare a penetrant aqueous solution with a mass concentration of 0.1 - 5%. Step 4: Mix the phosphorus tailings powder from Step 1 and the synergist from Step 2 in proportion and put them into a granulator, spray the penetrant aqueous solution in proportion for granulation, screening, and drying to obtain the medium and trace element granular fertilizer prepared from 3 - 5 mm phosphorus tailings.

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