Slow-release fertilizer suitable for plant-growing concrete and preparation method of slow-release fertilizer

Abstract

The invention belongs to the technical field of functional concrete additives, and particularly relates to a slow-release fertilizer suitable for plant-growing concrete and a preparation method of the slow-release fertilizer. The slow-release fertilizer is prepared from the following raw materials: a fertilizer, a capsule wall material, a binder, attapulgite powder and deionized water. The slow-release fertilizer disclosed by the invention is added into the plant-growing concrete, the pore liquid penetrates through pores in the capsule wall to enter the slow-release fertilizer under the swelling action, part of the slow-release fertilizer loaded by the attapulgite powder is taken out, and meanwhile, the functions of slowly releasing the internal fertilizer and continuously maintaining the fertility of the plant-growing concrete are realized by adding the binder and regulating and controlling the release of the internal fertilizer.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional concrete additives, and particularly relates to a slow-release fertilizer applicable to vegetation concrete and a preparation method thereof. Background Art

[0002] Vegetation concrete is a good slope protection material, which skillfully combines engineering protection and ecological restoration. However, due to the lack of fertility in the concrete matrix itself, the cultivation and continuous growth of concrete vegetation have become challenges, which have limited the functions of vegetation concrete to a certain extent and restricted its large-scale utilization.

[0003] Regarding the problems of the cultivation and continuous growth of vegetation on vegetation concrete, there are some preventive and treatment methods, including adjusting the formula of vegetation concrete, subsequent continuous fertilization, etc. However, these measures all have certain defects. For example, when adding more organic matter and sandy loam in the design of the vegetation concrete formula, the strength of the vegetation concrete itself will be greatly reduced, deteriorating its slope protection performance. Subsequent continuous fertilization not only wastes manpower and material resources, but also is affected by environmental weather, and its effect is difficult to guarantee. Another defect of the continuous fertilization method is that the fertilizer after fertilization is easily dissolved and lost quickly by rainwater or irrigation water, resulting in concentrated nutrient supply in a short time, insufficient later fertilizer efficiency, and affecting the growth of plants. In addition, the direct addition of fertilizer may lead to too high local nutrients, causing an increase in the salt concentration of the soil solution and causing the phenomenon of "burning roots" of the vegetation roots.

[0004] With the development of slow-release fertilizers, by coating the fertilizers, although the problem of concentrated nutrient supply has been solved, there are also problems such as uneven nutrient release, large differences in performance in different application environments, and lack of environmental adaptability. Therefore, while ensuring the controlled release effect of the slow-release fertilizer, reducing the impact of the slow-release fertilizer on the strength of vegetation concrete, effectively solving the problems of uneven release of fertilizer nutrients and waste of manpower and material resources in subsequent continuous fertilization, and developing a slow-release fertilizer with environmental adaptability and applicable to vegetation concrete is crucial. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a slow-release fertilizer applicable to vegetation concrete and a preparation method thereof.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A slow-release fertilizer applicable to vegetation concrete, calculated by weight, the raw materials used are: 15-30 parts of fertilizer, 4.5-23 parts of capsule wall material, 1-3 parts of binder, 10-20 parts of activated attapulgite powder, and 76-228 parts of deionized water.

[0008] The activated attapulgite powder is obtained by activating attapulgite powder at 150-200°C for 3-6 hours. The particle size of the attapulgite powder is <74μm, and the water content is <13%.

[0009] The particle size of the slow-release fertilizer is 1.4-3.4mm.

[0010] The wall material of the capsule is one or more of polyethylene glycol and aminotrimethylene phosphonic acid, and the binder is one or more of gelatin and carboxymethyl cellulose.

[0011] A method for preparing a slow-release fertilizer, comprising the following steps:

[0012] 1) Activate attapulgite powder at 150-200°C for 3-6 hours to obtain activated attapulgite powder;

[0013] 2) Weigh each raw material according to the proportion;

[0014] 3) Add the fertilizer to deionized water to make a solution, then add the activated attapulgite powder and stir at a stirring speed of 120-200r / min, then carry out impregnation loading, and filter after completion;

[0015] 4) Dry and crush the filtered activated attapulgite powder, and the crushing particle size is <74μm;

[0016] 5) Prepare a binder solution, and granulate the dried activated attapulgite powder with the binder solution (gelatin solution: 60-80°C, concentration 1-3%, carboxymethyl cellulose solution: concentration 0.1-0.3%) (the rotation speed of the disk granulator is 10-30r / min) to obtain fertilizer particles with a particle size of 1-3mm;

[0017] 6) Dry the fertilizer particles;

[0018] 7) Prepare a 1-5% polyethylene glycol solution or a 0.1-1% aminotrimethylene phosphonic acid solution as the wall material of the capsule at 60-80°C with a stirring speed of 200-600r / min;

[0019] 8) Coating granulate the fertilizer particles with the wall material of the capsule, the coating thickness is 0.2-0.5mm, and finally dry.

[0020] During the impregnation loading in step 3), soak for 12-24 hours at 60-80°C for impregnation.

[0021] During the drying in steps 4) and 6), dry in a forced-air drying oven at 60-80°C for 4-8 hours.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are:

[0023] 1. When the slow-release fertilizer of the present invention is used, it is added to the preparation of vegetation concrete, which is equivalent to pre-burying the slow-release fertilizer in advance. When encountering rain or irrigation, the wall of the capsule absorbs water and swells, becoming loose and showing a pore structure. The pore liquid passes through the pores on the wall of the capsule and enters the inside of the slow-release fertilizer, taking out some of the slow-release fertilizer loaded on the attapulgite powder and releasing it into the pores of the concrete, thereby providing nutrients for the plants in the concrete.

[0024] 2. With the addition of the binder, the inside of the slow-release fertilizer is firmly adhered and formed by the binder, and the process of fertilizer release is relatively slow. Thus, the release rate of the fertilizer inside the slow-release fertilizer can be regulated, and the controlled release of the fertilizer in the vegetation concrete for a long time can be achieved, reducing the excessive supply and loss of fertilizer nutrients, thereby continuously maintaining the fertility of the vegetation concrete and improving the utilization rate of the fertilizer.

[0025] 3. In the present invention, the attapulgite powder is activated. The structure of the activated attapulgite powder is loose and porous, the specific surface area and pore volume increase, and the loading capacity is greatly improved, and the fertilizer can be completely loaded.

[0026] 4. The capsule wall material and binder selected in the present invention are self-degrading polymer materials, which can avoid the components from affecting the strength of the vegetation concrete and the growth effect of plants.

[0027] 5. When the slow-release fertilizer of the present invention is made, it is preferably granulated by a disc granulator to obtain a particle size within a specified range. A certain particle size can not only ensure a better slow-release effect and a stronger fertilizer loading capacity, but also will not damage the strength and structure of the vegetation concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the external view of the slow-release fertilizer of the present invention.

[0029] Figure 2 It is the internal structure diagram of the slow-release fertilizer of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following examples are used to illustrate the specific implementation manners of the present invention, but the following examples are only used to illustrate the present invention in detail and do not limit the scope of the present invention in any way.

[0031] In the following examples, the particle size of the attapulgite powder used is <74 μm, and the water content is <13%.

[0032] Example 1:

[0033] A slow-release fertilizer suitable for vegetation concrete, and the raw materials used are:

[0034] 15 g of urea, 16 g of capsule wall material (polyethylene glycol), 1 g of gelatin solution, 10 g of activated attapulgite powder and 76 g of deionized water.

[0035] The preparation method is as follows:

[0036] 1) Activate attapulgite powder at 180 °C for 5 h to obtain activated attapulgite powder;

[0037] 2) Weigh each raw material according to the amount;

[0038] 3) Add urea to deionized water to make a solution, then add the activated attapulgite powder and stir at a stirring speed of 120 r / min. Then soak it in a constant temperature water bath at 70 °C for 20 h for impregnation loading, and then filter;

[0039] 4) Dry the filtered activated attapulgite powder in a blast drying oven at 70 °C for 5 h and crush it, with the crushing particle size < 74 μm;

[0040] 5) Prepare a 2% gelatin solution at 70 °C as a binder, and granulate the activated attapulgite powder using a disk granulator with a rotation speed of 20 r / min. The gelatin solution is atomized by the atomizing nozzle of the disk granulator onto the activated attapulgite powder material in the disk, and control the particle size to 1 mm to obtain fertilizer particles;

[0041] 6) Put the fertilizer particles into a blast drying oven at 70 °C and dry for 5 h;

[0042] 7) Prepare a 3% polyethylene glycol solution as the wall material at 70 °C with a stirring speed of 400 r / min;

[0043] 8) Put the fertilizer particles into the disk granulator again, and atomize the wall material through the atomizing nozzle of the disk granulator onto the fertilizer particle material in the disk. Control the environmental humidity < 10%, the rotation speed of the granulator is 10 r / min, the working time is 20 min, and the size of the slow-release fertilizer particles after drying is 1.4 mm, and the wall thickness is 0.2 mm.

[0044] Example 2

[0045] A slow-release fertilizer suitable for vegetation concrete, and the raw materials used are:

[0046] 20 g of urea, 23 g of wall material (aminotrimethylene phosphonic acid), 3 g of carboxymethyl cellulose solution, 15 g of activated attapulgite powder and 150 g of deionized water.

[0047] The preparation method is as follows:

[0048] 1) Activate attapulgite powder at 200 °C for 3 h to obtain activated attapulgite powder;

[0049] 2) Weigh each raw material according to the amount;

[0050] 3) Add urea to deionized water to make a solution, then add activated attapulgite powder and stir at a stirring speed of 200 r / min. Then soak it in a constant temperature water bath at 80 °C for 12 h for impregnation loading, and filter after completion;

[0051] 4) The filtered activated attapulgite powder is dried in a blast drying oven at 80 °C for 4 h and then crushed, and the crushing particle size is <74 μm;

[0052] 5) Prepare a 0.2% carboxymethyl cellulose solution as a binder, and granulate the activated attapulgite powder using a disk granulator with a rotation speed of 30 r / min. The carboxymethyl cellulose solution is atomized by the atomizing nozzle of the disk granulator onto the activated attapulgite powder material in the disk, and the particle size is controlled to be 1.5 mm to obtain fertilizer granules;

[0053] 6) Put the fertilizer granules into a blast drying oven at 80 °C and dry for 4 h;

[0054] 7) Prepare a 1% aminotrimethylenephosphonic acid solution as a wall material at 60 °C with a stirring speed of 600 r / min;

[0055] 8) Put the fertilizer granules into the disk granulator again, and atomize the wall material onto the fertilizer granule material in the disk through the atomizing nozzle of the disk granulator. Control the environmental humidity <10%, the rotation speed of the granulator is 10 r / min, and the working time is 20 min. The size of the slow-release fertilizer granules after drying is 2.1 mm, and the wall thickness is 0.3 mm.

[0056] Example 3

[0057] A slow-release fertilizer suitable for vegetation concrete, and the raw materials used are:

[0058] 20 g of potassium dihydrogen phosphate, 23 g of wall material (aminotrimethylenephosphonic acid), 3 g of gelatin solution, 15 g of activated attapulgite powder and 150 g of deionized water.

[0059] The preparation method is as follows:

[0060] 1) Activate attapulgite powder at 150 °C for 6 h to obtain activated attapulgite powder;

[0061] 2) Weigh each raw material according to the amount;

[0062] 3) Add potassium dihydrogen phosphate to deionized water to make a solution, then add activated attapulgite powder and stir at a stirring speed of 160 r / min. Then soak it in a constant temperature water bath at 60 °C for 24 h for impregnation loading, and filter after completion;

[0063] 4) The filtered activated attapulgite powder is dried in a blast drying oven at 60 °C for 8 h and then crushed, and the crushing particle size is <74 μm;

[0064] 5) Prepare a 3% gelatin solution at 60°C as a binder, and granulate the activated attapulgite powder using a disk granulator with a rotation speed of 10 r / min. The gelatin solution is atomized by the atomizing nozzle of the disk granulator onto the activated attapulgite powder material in the disk, and fertilizer granules with a particle size of 2 mm are obtained by controlling the particle size.

[0065] 6) Put the fertilizer granules into a forced-air drying oven at 60°C and dry for 8 hours.

[0066] 7) Prepare a 1% aminotrimethylene phosphonic acid solution as the wall material at 80°C with a stirring speed of 200 r / min.

[0067] 8) Put the fertilizer granules into the disk granulator again, and atomize the wall material through the atomizing nozzle of the disk granulator onto the fertilizer granule material in the disk. Control the environmental humidity < 10%, the rotation speed of the granulator is 10 r / min, the working time is 20 min, and the size of the slow-release fertilizer granules after drying is 3 mm, and the wall thickness is 0.5 mm.

[0068] Example 4

[0069] Different from Example 1, the attapulgite powder is not activated.

[0070] A slow-release fertilizer suitable for vegetation concrete, and the raw materials used are:

[0071] 15 g of urea, 16 g of wall material, 1 g of gelatin solution, 10 g of attapulgite powder, and 76 g of deionized water.

[0072] The preparation method refers to Example 1, except that the attapulgite powder does not undergo the activation step.

[0073] Example 5

[0074] A slow-release fertilizer suitable for vegetation concrete, and the raw materials used are:

[0075] 15 g of urea, 16 g of wall material, 1 g of gelatin solution, 10 g of attapulgite powder, and 76 g of deionized water.

[0076] The preparation method refers to Example 1, except that the activation temperature of the attapulgite powder is 300°C.

[0077] Example 6

[0078] A slow-release fertilizer suitable for vegetation concrete, and the raw materials used are:

[0079] 15 g of urea, 16 g of wall material, 1 g of gelatin solution, 10 g of attapulgite powder, and 76 g of deionized water.

[0080] The preparation method refers to Example 1, except that the activation temperature of the attapulgite powder is 90°C.

[0081] Example 7

[0082] A slow-release fertilizer applicable to vegetation concrete, with the following raw materials:

[0083] 15 g of urea, 16 g of capsule wall material, 1 g of gelatin solution, 10 g of activated carbon, and 76 g of deionized water.

[0084] The preparation method refers to Example 1. The difference is that activated attapulgite powder is replaced by activated carbon for fertilizer loading.

[0085] I. Measure the particle size and wall thickness of the slow-release fertilizers prepared in Examples 1-7, and test and calculate the particle strength and water absorption rate. The results are listed in Table 1.

[0086] Table 1 Performance determination of slow-release fertilizers

[0087]

[0088] As can be seen from Table 1, the slow-release fertilizers prepared in Examples 1-3 have moderate average particle size, reasonable wall thickness, and particle strength and water absorption rate meeting the use requirements. The particle strength can reach more than 20 N.

[0089] In Example 4, although the attapulgite powder without thermal activation treatment has a certain particle strength and barely meets the requirements for the stability during the mixing and transportation of vegetation concrete, its adsorption ability is poor, resulting in poor fertilizer loading ability. Most of the fertilizers are in an independent and dispersed state inside the slow-release fertilizer and it is difficult to form an effective combination and fixation with the attapulgite powder. This structural feature will significantly weaken the slow-release performance of the slow-release fertilizer and thus have a very adverse impact on the overall efficacy of the slow-release fertilizer.

[0090] In Example 5, too high an activation temperature will cause the sintering process of the porous pore structure in the attapulgite powder, resulting in a decrease in specific surface area and pore volume, affecting its adsorption ability and water absorption rate, and leading to a decline in its fertilizer loading ability, thus affecting the effect of the slow-release fertilizer.

[0091] In Example 6, too low an activation temperature of the attapulgite powder will lead to an insufficient activation process, unreasonable pore distribution, lack of micropores and mesopores beneficial for adsorption, and will reduce the particle strength and water absorption rate of the slow-release fertilizer, affecting the stability and controlled-release effect of the slow-release fertilizer.

[0092] In Example 7, when using activated carbon for fertilizer loading, it can be seen that the particle strength is too low to meet the requirements, and cracking will occur during the preparation process of vegetation concrete. Moreover, as a loading material, activated carbon has a low water absorption rate, affecting the effective release of fertilizers.

[0093] II. Application experiment

[0094] Mix ordinary Portland cement: coarse aggregate: water: water reducer: nutrient soil = 20:60:12:0.5:7.5 in proportion to prepare vegetation concrete. Incorporate the slow-release fertilizers prepared in Examples 1-7 of the present invention into the vegetation concrete at a dosage of 8 wt.%, without adding slow-release fertilizer in Blank Group 1, and directly add fertilizer particles without coating and lacking the slow-release core-shell structure in Blank Group 2. Make 150 mm×150 mm×150 mm test blocks respectively, and after curing, test their initial nutrient release rate (the mass fraction of nutrient release within 24 h accounting for the total amount), cumulative nutrient release rate (the mass fraction of nutrient release within 28 d accounting for the total amount), fertilizer efficiency period (the time required for the cumulative nutrient release rate to reach 80%), and 28-day compressive strength respectively. The results are shown in Table 2.

[0095] The difference between the preparation of Blank Group 2 and Example 1 is that the wall material is not used, and steps 7) and 8) are lacking in the preparation.

[0096] Table 2 Test results of nutrient release experiment for application examples

[0097]

[0098] It can be seen from Table 2 that compared with Blank Group 2, the nutrient release rate in Examples 1-3 slows down, greatly extending the fertilizer efficiency period. This is mainly related to the adoption of the slow-release core-shell structure and the extension of the fertilizer release process through the binder. Blank Group 2 has no wall, with a fast release rate and a short fertilizer efficiency period.

[0099] It can be seen from the data of Examples 1-3 that the thicker the wall, the longer the fertilizer efficiency period. This is mainly related to the effective release of the core. The thicker the wall, the lower the effective release rate of the core, and the better the slow-release effect, but all can meet the requirements. The type and dosage of the binder and wall material selected in the present invention also have a certain impact on the fertilizer efficiency period, but all can meet the requirements and should be flexibly adjusted according to actual application requirements.

[0100] The slow-release fertilizers in Examples 1-3 have little impact on the compressive strength and will not deteriorate the slope protection performance of the vegetation concrete.

[0101] It can be seen from Example 4 that adding unactivated attapulgite powder results in a relatively fast initial nutrient release rate, which affects the fertilizer efficiency period and cannot achieve the expected slow-release effect, indicating that the load effect of unactivated attapulgite powder on fertilizers is limited and cannot meet the requirements.

[0102] It can be seen from Example 5 that although the attapulgite powder with too high activation temperature has a certain fertilizer loading capacity, due to the sintering process, the structure becomes dense, the water absorption rate decreases, which affects the effective release of fertilizers, and the sintering process also makes the loading capacity of attapulgite powder worse, affecting the slow-release effect of attapulgite powder.

[0103] It can be seen from Example 6 that attapulgite powder with too low activation temperature has poor loading capacity for fertilizers, the nutrient release is concentrated in the early stage, the fertilizer efficiency period is short, and it cannot meet the requirements of the slow-release effect of slow-release fertilizers for vegetation concrete.

[0104] In Example 7, activated carbon was used to load the fertilizer. Although the low water absorption rate resulted in a long fertilizer efficiency period, the nutrient release was concentrated in the early stage, and the compressive strength of the test block was too low to meet the actual needs.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention should be covered within the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.

Claims

1. A slow-release fertilizer applicable to vegetation concrete, characterized in that, The raw materials used, by weight parts, are: 15 - 30 parts of fertilizer, 4.5 - 23 parts of capsule wall material, 1 - 3 parts of binder, 10 - 20 parts of activated attapulgite powder, and 76 - 228 parts of deionized water.

2. The slow-release fertilizer according to claim 1, wherein The activated attapulgite powder is obtained by activating attapulgite powder at 150 - 200 °C for 3 - 6 h.

3. The slow-release fertilizer according to claim 1, wherein The particle size of the slow - release fertilizer is 1.4 - 3.4 mm.

4. The slow-release fertilizer according to claim 1, wherein, The fertilizer is one or more of urea and potassium dihydrogen phosphate; the capsule wall material is one or more of polyethylene glycol and amino trimethylene phosphonic acid; the binder is one or more of gelatin and carboxymethyl cellulose.

5. A method for preparing the slow-release fertilizer according to claim 1, characterized in that, It includes the following steps: 1) Activate attapulgite powder at 150 - 200 °C for 3 - 6 h to obtain activated attapulgite powder; 2) Weigh each raw material according to the proportion; 3) Add the fertilizer into deionized water to make a solution, then add the activated attapulgite powder and stir, then carry out impregnation loading, and filter after completion; 4) Dry and crush the filtered activated attapulgite powder; 5) Prepare a binder solution, and granulate the dried activated attapulgite powder with the binder solution (the rotation speed of the disk granulator is 10 - 30 r / min) to obtain fertilizer particles; 6) Dry the fertilizer particles; 7) Prepare a 1 - 5% polyethylene glycol solution or a 0.1 - 1% amino trimethylene phosphonic acid solution as the capsule wall material; 8) Coating - granulate the fertilizer particles with the capsule wall material, and finally dry.

6. The preparation method according to claim 5, characterized in that, When carrying out the impregnation loading in step 3), soak at 60 - 80 °C for 12 - 24 h for impregnation.

7. The preparation method according to claim 5, characterized in that, When drying in steps 4) and 6), dry in a forced - air drying oven at 60 - 80 °C for 4 - 8 h.

Images