Methods for preparing silicon-calcium-potassium-magnesium fertilizer from tailings, and the application of silicon-calcium-potassium-magnesium fertilizer.

Abstract

This disclosure provides a method for preparing silicon-calcium-potassium-magnesium fertilizer from tailings, the fertilizer itself, and its applications. The method includes mixing tailings, a calcium source, and agricultural waste powder in a specific ratio to obtain a solid mixture; adding an alkaline activator to the solid mixture and stirring until homogeneous to obtain a slurry; subjecting the slurry to a hydrothermal reaction in a closed reactor; and removing the reaction product after the hydrothermal reaction, filtering, and drying to obtain the silicon-calcium-potassium-magnesium fertilizer. This method is simple and easy to implement, has a high resource utilization rate, and the preparation process is carried out at a relatively low temperature, consuming less energy and effectively reducing production costs. The raw material for this method mainly comes from bulk solid waste—tailings—achieving resource-based, green, and efficient utilization of tailings, realizing comprehensive waste utilization, and providing a feasible solution for the application of ultrafine-grained tailings, which are currently difficult to treat. The silicon-calcium-potassium-magnesium fertilizer prepared by this method fully meets the national standard requirements for its content.

Description

TECHNICAL FIELD

[0001] The embodiment of the present disclosure belongs to the technical field of mineral fertilizer preparation, and particularly relates to a method for preparing silicon-calcium-potassium-magnesium fertilizer from tailings, the silicon-calcium-potassium-magnesium fertilizer and application. BACKGROUND

[0002] At present, the disposal technology of tailings mostly uses coarse-grained tailings, or produces low-end products such as bricks and ceramsite, and the bulk disposal of superfine tailings is still full of difficulties and challenges.

[0003] The silicon-calcium-potassium-magnesium fertilizer is an alkaline soil conditioner formed by calcining phosphogypsum, potash feldspar and the like at high temperature, which can not only adjust the soil, but also supplement various macroelements, mesoelements and microelements, can effectively overcome the deficiency of lime and the like in causing soil compaction, has good application effect on various crops, and has small influence on soil environment, and is a new type of environment-friendly soil conditioner.

[0004] At present, there are many preparation methods of the silicon-calcium-potassium-magnesium fertilizer. For example, CN202111014519 discloses a method for producing silicon-calcium-potassium-magnesium fertilizer from dolomitic limestone, which uniformly mixes dolomitic limestone, potash feldspar, phosphogypsum, additives I and II, and performs compression molding, drying, calcination, cooling, ball milling and granulation to obtain the silicon-calcium-potassium-magnesium fertilizer; Guizhou University Resource Chemical Institute produces silicon-calcium-potassium fertilizer by a "powder grinding block making tunnel kiln sintering process", which first crushes potash feldspar and limestone, uniformly mixes the crushed materials, then performs powder grinding, water adding and compression molding to form blocks, and then sintering in a tunnel kiln, and the sintered blocks are crushed and ground to obtain the silicon-calcium-potassium fertilizer product and the like.

[0005] The existing preparation methods of the silicon-calcium-potassium-magnesium fertilizer have the following problems: (1) the spheroids are calcined at high temperature in a shaft kiln, which easily causes uneven sintering temperature, low average conversion rate of potassium, and phenomena such as large block formation, adhesion to the kiln wall and leakage of raw materials in the kiln, which seriously affect the product quality and production efficiency; (2) the production temperature is high, the energy consumption is large, and the technology is difficult to land; (3) the raw materials are primary resources, and the activation of silicates is difficult; and (4) the bulk disposal of superfine tailings is a difficulty and challenge in the comprehensive utilization of tailings.

[0006] In view of the above problems, it is necessary to provide a method for preparing silicon-calcium-potassium-magnesium fertilizer from tailings, the silicon-calcium-potassium-magnesium fertilizer and application, which are reasonable in design and effective in solving the above problems. SUMMARY

[0007] The embodiment of the present disclosure aims to at least solve one of the technical problems in the prior art, and provides a method for preparing silicon-calcium-potassium-magnesium fertilizer from tailings, the silicon-calcium-potassium-magnesium fertilizer and application.

[0008] One aspect of the embodiment of the present disclosure provides a method for preparing silicon-calcium-potassium-magnesium fertilizer from tailings, which comprises:

[0009] Mixing the tailings, the calcium source and the agricultural waste powder in proportion to obtain a solid mixture;

[0010] Adding an alkali activator to the solid mixture and stirring to obtain a mixture slurry;

[0011] Carrying out a hydrothermal reaction on the mixture slurry in a closed reactor;

[0012] Taking out the reaction product after the hydrothermal reaction, and obtaining a silicon-calcium-potassium-magnesium fertilizer after filtration and drying.

[0013] Optionally, the molar ratio of silicon to calcium in the tailings to the calcium source ranges from 1:0.2 to 1:1.6.

[0014] The weight ratio of the tailings to the agricultural waste powder ranges from 100:1 to 1:0.

[0015] Optionally, the calcium source is quicklime, phosphogypsum or calcium hydroxide.

[0016] The agricultural waste is straw, rice husk or coconut shell.

[0017] The tailings are molybdenum tailings, iron tailings or gold tailings.

[0018] Optionally, the calcium source is quicklime, and the mass ratio of the tailings to the quicklime ranges from 1:0.3 to 1:1.2.

[0019] Optionally, the concentration of the alkali activator ranges from 0.1 mol / L to 1.4 mol / L.

[0020] The alkali activator is a NaOH solution or a KOH solution.

[0021] Optionally, the mass-to-volume ratio of the solid mixture to the alkali activator ranges from 1:0.5 g / mL to 1:10 g / mL.

[0022] Optionally, the particle size of the tailings and the calcium source is less than 200 mesh, and the particle size of the agricultural waste powder is less than 80 mesh.

[0023] Optionally, the temperature of the hydrothermal reaction ranges from 130°C to 200°C, and the time of the hydrothermal reaction ranges from 3 hours to 15 hours.

[0024] Another aspect of the embodiments of the present disclosure provides a silicon calcium potassium magnesium fertilizer, which is prepared by the method described above, wherein the pH value of the silicon calcium potassium magnesium fertilizer ranges from 10.41 to 11.00, the content of silicon ranges from 6.52% to 9.61%, the content of K2O ranges from 3.17% to 6.8%, the content of Ca ranges from 22.8% to 26.1%, and the content of Mg ranges from 2.05% to 2.14%.

[0025] Another aspect of the embodiments of the present disclosure provides an application of the silicon calcium potassium magnesium fertilizer prepared by the method described above, and the silicon calcium potassium magnesium fertilizer is applied to soil remediation.

[0026] The method for preparing the silicon calcium potassium magnesium fertilizer from the tailings, the silicon calcium potassium magnesium fertilizer and the application thereof have the advantages that the preparation method is simple and easy to implement, the resource comprehensive utilization rate is high, the preparation process is performed at a relatively low temperature, the energy consumption is low, and the production cost is effectively reduced. The raw material of the preparation method is mainly derived from the bulk solid waste, i.e., the tailings, the tailings are efficiently utilized in a resourceful and green manner, the comprehensive utilization of waste is achieved, and a feasible solution is provided for the application of the superfine particle tailings which are difficult to handle at the present stage. The content of the silicon calcium potassium magnesium fertilizer prepared by the preparation method fully meets the index requirements of GB / T 36207-2018, and the silicon calcium potassium magnesium fertilizer has multiple effects such as soil remediation, soil water retention, adsorption of heavy metal ions in soil, reduction of soil bulk density, and improvement of soil permeability. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 FIG. 1 is a flowchart of a method for preparing a silicon calcium potassium magnesium fertilizer from tailings according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0028] In order for those skilled in the art to better understand the technical solutions of the embodiments of the present disclosure, the embodiments of the present disclosure are further described in detail below with reference to the drawings and specific embodiments.

[0029] As shown in FIG. 1, one aspect of the embodiments of the present disclosure provides a method S100 for preparing a silicon calcium potassium magnesium fertilizer from tailings, and the method S100 comprises the following steps. Figure 1

[0030] S110, uniformly mixing the tailings, the calcium source and the agricultural waste powder in proportion to obtain a solid mixture.

[0031] First, the tailings and the calcium source are respectively ground and crushed to a particle size of less than 0.0740 mm. That is, the tailings and the calcium source are respectively ground and crushed to a particle size of less than 200 mesh. The agricultural waste is coarsely crushed and dried, and then ground and crushed to a particle size of less than 0.178 mm, that is, the particle size of the agricultural waste is less than 80 mesh. ​

[0032] Secondly, the ground tailings, calcium source and agricultural waste powder are mixed in a certain proportion to obtain a solid mixture.

[0033] In the embodiment, the main component of the tailings is silicon dioxide, and the molar ratio of silicon to calcium in the tailings to the calcium source ranges from 1:0.2 to 1:1.6. Specifically, the molar ratio of silicon to calcium in the tailings to the calcium source can be 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6. Further preferably, the molar ratio of silicon to calcium in the tailings to the calcium source ranges from 1:0.3 to 1:0.5, and the use of the above preferred ratio can make the silicon component in the tailings more effectively activated.

[0034] Further preferably, in the embodiment, the calcium source is quicklime, and the mass ratio of the tailings to the quicklime ranges from 1:0.3 to 1:1.2. Specifically, the mass ratio of the tailings to the quicklime can be 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, and preferably, the mass ratio of the tailings to the quicklime ranges from 1:0.8 to 1:1.

[0035] The weight ratio of the tailings to the agricultural waste powder ranges from 100:1 to 1:0. Specifically, the weight ratio of the tailings to the agricultural waste powder can be 100:1, 90:1, 80:1, 70:1, 60:1, 50:1, 40:1, 30:1, 20:1, 10:1, 1:0. Further preferably, the weight ratio of the tailings to the agricultural waste powder ranges from 70:1 to 1:0, and the use of the above preferred ratio can make the silicon component in the tailings more effectively activated.

[0036] It should be noted that the tailings can be common bulk solid waste-tailings such as molybdenum tailings, iron tailings or gold tailings. The type of tailings is not specifically limited in the embodiment and can be selected according to actual needs. The calcium source can be common tailings such as quicklime, phosphogypsum or calcium hydroxide. The type of calcium source is not specifically limited in the embodiment and can be selected according to actual needs. The agricultural waste can be common agricultural waste biomass such as straw, rice husk or coconut shell, and the type of agricultural waste is not specifically limited in the embodiment and can be selected according to actual needs.

[0037] In the above embodiments, agricultural waste uses common agricultural waste biomass such as rice husk, straw or coconut shell, etc. The hydrothermal reaction of agricultural waste biomass resources generates biochar, silicon potassium and other element hydrolysis conversion. On the one hand, it reduces the pollution of burning agricultural waste biomass to the environment, and on the other hand, it turns waste into treasure and makes full use of resources. The addition of agricultural waste biomass can promote the activation process of silicon, potassium and other components in the tailings; increase the conditioning of silicon, calcium, potassium and magnesium fertilizer products on soil carbon pool, soil salt base saturation and fertilizer retention capacity.

[0038] In the above embodiments, the tailings are common bulk solid waste-tailings such as molybdenum tailings, iron tailings or gold tailings, which realizes the resourceization, green and efficient utilization of tailings, realizes the comprehensive utilization of waste, and provides a feasible solution for the application of ultra-fine particle size tailings which are difficult to handle at present.

[0039] S120, adding an alkali activator to the solid mixture and stirring uniformly to obtain a mixture slurry.

[0040] Specifically, the alkali activator is added to the solid mixture in a mass-volume ratio of 1:0.5 g / mL to 1:10 g / mL, and stirred uniformly to obtain a mixture slurry. The mass-volume ratio of the solid mixture to the alkali activator can be 1:0.5 g / mL, 1:1 g / mL, 1:1.5 g / mL, 1:2 g / mL, 1:3 g / mL, 1:5 g / mL, 1:10 g / mL. Further preferably, the mass-volume ratio of the solid mixture to the alkali activator is 1:1.5-1:5 g / mL.

[0041] Illustratively, in this embodiment, the concentration of the alkali activator ranges from 0.1 mol / L to 1.4 mol / L. Specifically, the concentration of the alkali activator can be 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L. Further preferably, the concentration of the alkali activator is 0.4-1 mol / L.

[0042] Illustratively, in this embodiment, the alkali activator can use NaOH solution or KOH solution, or other alkali activators, which can be selected according to actual needs.

[0043] S130, performing a hydrothermal reaction on the mixed slurry in a closed reactor.

[0044] Specifically, in the present embodiment, the mixed slurry is subjected to a hydrothermal reaction in a reaction kettle. The temperature range of the hydrothermal reaction is 130-200°C. Further, the temperature of the hydrothermal reaction can be 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C. Preferably, the temperature of the hydrothermal reaction is 170-200°C.

[0045] In the present embodiment, the time range of the hydrothermal reaction is 3-15h. Further, the time of the hydrothermal reaction can be 3h, 5h, 8h, 9h, 10h, 12h, or 15h. Preferably, the time of the hydrothermal reaction is 3-9h.

[0046] S140, the reaction product after the hydrothermal reaction is taken out, filtered, and dried to obtain the silicon-calcium-potassium-magnesium fertilizer.

[0047] Specifically, the silicon-calcium-potassium-magnesium fertilizer product is separated from the liquid, which can be achieved by filtration, pressure filtration, vacuum filtration, etc. After separation, drying is required, and finally the silicon-calcium-potassium-magnesium fertilizer meeting the national standard is obtained.

[0048] The present disclosure provides a method for preparing a silicon-calcium-potassium-magnesium fertilizer from tailings. The preparation method is simple and easy to implement, has a high resource comprehensive utilization rate, is carried out at a relatively low temperature, consumes less energy, and effectively reduces production costs. The raw material of the present preparation method is mainly derived from bulk solid waste-tailings, which realizes the resourceization and green and efficient utilization of tailings, achieves comprehensive utilization of waste, and provides a feasible solution for the application of ultra-fine particle tailings which are difficult to handle at the present stage.

[0049] Another aspect of the present disclosure provides a silicon-calcium-potassium-magnesium fertilizer prepared by the method described above. The specific steps of the method have been described in detail above, and will not be repeated here. According to the silicon-calcium-potassium-magnesium fertilizer prepared by the above method, the pH value of the silicon-calcium-potassium-magnesium fertilizer ranges from 10.41 to 11.00, the content of silicon ranges from 6.52% to 9.61%, the content of K2O ranges from 3.17% to 6.8%, the content of Ca ranges from 22.8% to 26.1%, and the content of Mg ranges from 2.05% to 2.14%.

[0050] The silicon-calcium-potassium-magnesium fertilizer prepared by the present preparation method fully meets the index requirements of GB / T36207-2018, and has multiple effects such as soil repair, soil water retention, adsorption of heavy metal ions in soil, reduction of soil bulk density, and improvement of soil permeability.

[0051] Another aspect of the present disclosure provides an application of the silicon-calcium-potassium-magnesium fertilizer prepared by the above method. The silicon-calcium-potassium-magnesium fertilizer is applied to soil repair.

[0052] Specifically, the silicon calcium potassium magnesium fertilizer is an alkaline soil conditioner formed by calcining phosphogypsum, potassium feldspar and the like at high temperature, which can not only adjust the soil and supplement various macroelements, medium elements and trace elements, but also effectively overcome the deficiency of lime and the like in causing soil compaction, has good application effect on various crops, has small influence on the soil environment, and is a new type of environment-friendly soil conditioner.

[0053] The method for preparing a silicon calcium potassium magnesium fertilizer from tailings, the silicon calcium potassium magnesium fertilizer and the application thereof in the embodiments of the present disclosure are further illustrated through several specific examples.

[0054] Example 1

[0055] The present embodiment is a method for preparing a silicon calcium potassium magnesium fertilizer from tailings and the silicon calcium potassium magnesium fertilizer, which specifically comprises the following steps:

[0056] According to the silicon calcium molar ratio of 1:0.42 between the molybdenum tailings and the quicklime and the mass ratio of 70:1 between the molybdenum tailings and the straw, the solid materials are mixed to obtain a solid mixture, the solid mixture is dissolved in a 0.5 mol / L KOH solution to form a mixed slurry, the ratio of the solid mixture to the KOH solution is controlled to be 1:2 g / mL, the mixed slurry is subjected to hydrothermal reaction in a reaction kettle, the reaction temperature is 170°C, the reaction time is 9 h, after the reaction, the slurry is filtered, and the solid is dried to obtain the silicon calcium potassium magnesium fertilizer.

[0057] As shown in Table 1, the silicon calcium potassium magnesium fertilizer prepared by the above steps has a K2O content of 4.64%, a silicon content of 8.6%, a Ca content of 25%, and a Mg content of 2.14%.

[0058] Example 2

[0059] The present embodiment is a method for preparing a silicon calcium potassium magnesium fertilizer from tailings and the silicon calcium potassium magnesium fertilizer, which specifically comprises the following steps:

[0060] According to the silicon calcium molar ratio of 1:0.42 between the molybdenum tailings and the quicklime and the mass ratio of 70:1 between the molybdenum tailings and the straw, the solid materials are mixed to obtain a solid mixture, the solid mixture is dissolved in a 1 mol / L KOH solution to form a mixed slurry, the ratio of the solid mixture to the KOH solution is controlled to be 1:3 g / mL, the mixed slurry is subjected to hydrothermal reaction in a reaction kettle, the reaction temperature is 180°C, the reaction time is 5 h, after the reaction, the slurry is filtered, and the solid is dried to obtain the silicon calcium potassium magnesium fertilizer.

[0061] As shown in Table 1, the silicon calcium potassium magnesium fertilizer prepared by the above steps has a K2O content of 6.17%, a silicon content of 8.86%, a Ca content of 26.1%, and a Mg content of 2.12%.

[0062] Example 3

[0063] According to the molar ratio of molybdenum tailings and quicklime of 1:0.34, and the mass ratio of molybdenum tailings and straw of 1:0, the solid materials are mixed to obtain a solid mixture, the solid mixture is dissolved in a 1 mol / L KOH solution to form a mixed slurry, the ratio of solid mixture to KOH solution is controlled to be 1:2 g / mL, the mixed slurry is subjected to hydrothermal reaction in a reaction kettle, the reaction temperature is 190°C, the reaction time is 3h, after the reaction, the slurry is filtered, and the solid is dried to obtain the silico-calcium-potassium-magnesium fertilizer.

[0064] As shown in Table 1, the silico-calcium-potassium-magnesium fertilizer prepared by the above steps has a K2O content of 5.87%, a silicon content of 7.78%, a Ca content of 24.9%, and a Mg content of 2.05%.

[0065] Table 1: Proportion of each component in the silico-calcium-potassium-magnesium fertilizer prepared in each example

[0066]

[0067] As can be seen from Table 1, the silico-calcium-potassium-magnesium fertilizer prepared by the preparation method has contents that meet the detection standards, fully meets the index requirements of GB / T 36207-2018, and has multiple effects such as soil repair, soil water retention, adsorption of soil heavy metal ions, reduction of soil bulk density, and improvement of soil permeability.

[0068] It can be understood that the above embodiments are only exemplary embodiments adopted to illustrate the principles of the disclosed embodiments, but the disclosed embodiments are not limited thereto. Various modifications and improvements can be made by those of ordinary skill in the art without departing from the spirit and essence of the disclosed embodiments, and these modifications and improvements are also considered within the protection scope of the disclosed embodiments.

Claims

1. A method for preparing a silicon calcium potassium magnesium fertilizer using tailings, characterized by, The method comprises: mixing tailings, a calcium source and agricultural waste powder in proportion to obtain a solid mixture; adding an alkali activator to the solid mixture and stirring to obtain a mixture slurry; subjecting the mixture slurry to a hydrothermal reaction in a closed reactor; wherein the temperature of the hydrothermal reaction ranges from 130 DEG C to 200 DEG C; removing the reaction product after the hydrothermal reaction, filtering and drying to obtain a silicon-calcium-potassium-magnesium fertilizer; the tailings are molybdenum tailings; the calcium source is quicklime, and the mass ratio of the tailings to the quicklime ranges from 1:0.3 to 1:1.2; the agricultural waste is straw, rice husk or coconut shell, and the weight ratio of the tailings to the agricultural waste powder ranges from 70:1 to 10:1; the alkali activator is a NaOH solution or a KOH solution, and the concentration of the alkali activator ranges from 0.1 mol / L to 1.4 mol / L; the pH value of the silicon-calcium-potassium-magnesium fertilizer ranges from 10.41 to 11.00, the silicon content ranges from 6.52% to 9.61%, the K2O content ranges from 3.17% to 6.8%, the Ca content ranges from 22.8% to 26.1%, and the Mg content ranges from 2.05% to 2.14%.

2. The method of claim 1, wherein, the molar ratio of silicon-calcium in the tailings to the calcium source ranges from 1:0.2 to 1:1.

6.

3. The method according to any one of claims 1 to 2, characterized in that, the mass-to-volume ratio of the solid mixture to the alkali activator ranges from 1:0.5 g / mL to 1:10 g / mL.

4. The method according to any one of claims 1 to 2, characterized in that, the particle size of the tailings and the calcium source is less than 200 mesh, and the particle size of the agricultural waste powder is less than 80 mesh.

5. The method according to any one of claims 1 to 2, characterized in that, the hydrothermal reaction time ranges from 3 h to 15 h.

6. A silicon calcium potassium magnesium fertilizer, characterized by, The silicon-calcium-potassium-magnesium fertilizer prepared by the method of any one of claims 1 to 5 has a pH value ranging from 10.41 to 11.00, a silicon content ranging from 6.52% to 9.61%, a K2O content ranging from 3.17% to 6.8%, a Ca content ranging from 22.8% to 26.1%, and a Mg content ranging from 2.05% to 2.14%.

7. Use of the silicon calcium potassium magnesium fertilizer produced according to the method of any one of claims 1 to 5, characterized in that, The silicon-calcium-potassium-magnesium fertilizer is applied to soil remediation.

Images