Composite mineralizing agent for treating sulfate type saline-alkali soil and application of composite mineralizing agent

Abstract

The invention relates to the technical field of treatment of sulfate type saline-alkali soil, in particular to a composite mineralizer for treating sulfate type saline-alkali soil and application of the composite mineralizer, and the composite mineralizer comprises acid modified calcium-based montmorillonite (Ca-MMT), nitrate intercalated calcium-based hydrotalcite (Ca-based LDH) and humic acid (HA). The composite mineralizing agent can be used for treating the sulfate type saline-alkali soil, and after the composite mineralizing agent is applied to the sulfate type saline-alkali soil, the three components can react with anions and cations in the sulfate type saline-alkali soil respectively, so that SO4 < 2-> and Na < + > are mineralized, OH <-> is consumed, the salt content and the alkali content of the sulfate type saline-alkali soil are reduced, and saline-alkali soil remediation is achieved. The composite mineralizing agent is low in cost, a good sulfate type saline-alkali soil treatment effect can be achieved within a short time, and mineralized products are stable, free of toxic substance precipitation and free of secondary pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of sulfate-type saline-alkali land treatment, and in particular to a composite mineralizer for treating sulfate-type saline-alkali land and application thereof. Background Art

[0002] Saline-alkali land is a general term for salt land, alkaline land, salinized land, and alkalized land. In soil science, it is also referred to as saline soil or saline-alkali soil. Its main characteristics are high salt content or alkalinity, poor soil structure, easy compaction, low organic matter content, poor nutrients, and weak soil fertility retention, which affect crop growth. It is a degraded soil with poor soil properties and low fertility.

[0003] Depending on the causes of formation and the main salt, saline-alkali land can be divided into chloride-type saline-alkali land dominated by NaCl, sulfate-type saline-alkali land dominated by Na2SO4, soda-type saline-alkali land dominated by Na2CO3 and NaHCO3, and secondary salinization-type saline-alkali land caused by excessive application of fertilizers.

[0004] It is well known that the management of sulfate-type saline-alkali land is difficult, and existing management technologies mainly include: chemical management, physical management, biological management and water conservancy project management. Chemical management is the most widely used management method at present. It is mainly achieved by applying various additives to saline-alkali land, such as gypsum, phosphogypsum, desulfurized gypsum, biochar, sulfur, black alum, humic acid, furfural residue and the like. It is easy to bring in other heavy metals or salt ions, and the adsorption product is unstable and easily desorbed, thereby causing secondary pollution. In addition, the traditional chemical method consumes a lot of water, and a large amount of water evaporation aggravates salinization, and long-term use may aggravate soil compaction. The management effects of means such as physical management, biological management and water conservancy project management are often limited by natural conditions such as topography and climate, and there are shortcomings such as slow effect, large water consumption, large engineering workload, high cost, and the need to invest a large amount of manpower, material resources and financial resources.

[0005] It can be seen that the existing treatment methods have their applicable conditions and limitations, and cannot completely solve the problem of sulfate saline-alkali land. There are a series of problems such as time-consuming, high cost, and easy to cause secondary pollution. Therefore, developing a low-cost, efficient, and pollution-free treatment method to repair sulfate saline-alkali land into arable land and ensure the normal growth of crops is of great significance for protecting the ecological environment and promoting sustainable agricultural development.

[0006] Layered double hydroxide (LDH), also known as hydrotalcite, is an anionic clay. LDH is simple to synthesize, low-cost, environmentally friendly, and can be easily produced under laboratory conditions. Due to its unique host-guest structure, LDH has adjustable main layers and interlayer anions under different pH conditions, adjustable grain size, a permanently positive charge on the main layers, strong electrostatic forces, a large specific surface area in a two-dimensional lamellar structure, and a high K sp Low, easy surface modification and excellent buffering capacity, etc., therefore, it is widely used in mineralization, adsorption, etc. Among them, calcium-based LDH materials have great application prospects in the field of soil remediation due to their high adsorption capacity.

[0007] Montmorillonite (MMT) is the main component of bentonite minerals. It is a natural layered magnesium aluminum silicate clay mineral with low cost. MMT consists of two silicon oxide tetrahedron layers and one aluminum oxide octahedron layer, with a typical layered structure. The interlayer is mostly Ca 2+ Due to its unique layered structure, MMT has many advantages such as interlayer cation exchangeability, large cation exchange capacity, strong adsorption capacity, and large specific surface area. It is widely used in adsorption, soil remediation and other fields. Summary of the Invention

[0008] To solve the above problems, the present invention provides a low-cost, high-efficiency, pollution-free composite mineralizer for treating sulfate saline-alkali land and its application, which can mineralize or consume excess SO4 in sulfate saline-alkali land. 2- OH - and Na + , thereby reducing the salt and alkali content of sulfate saline-alkali land and achieving the goal of saline-alkali land management.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A composite mineralizer for treating sulfate saline-alkali land, comprising a component A, a component B, and a component C; wherein the component A is acid-modified calcium-montmorillonite (Ca-MMT); the component B is nitrate-intercalated calcium-hydrotalcite (Ca-LDH); and the component C is humic acid (HA).

[0011] Furthermore, the acid-modified calcium montmorillonite (Ca-MMT) is calcium montmorillonite modified with dilute sulfuric acid, dilute hydrochloric acid, or dilute nitric acid. Preferably, the acid-modified calcium montmorillonite (Ca-MMT) is calcium montmorillonite modified with dilute sulfuric acid. The dilute sulfuric acid, dilute hydrochloric acid, or dilute nitric acid is obtained by diluting commercially available 95-98% sulfuric acid, hydrochloric acid, or nitric acid 100 times.

[0012] Furthermore, the solid-liquid ratio of the calcium-montmorillonite (Ca-MMT) to dilute sulfuric acid, dilute hydrochloric acid or dilute nitric acid is 1:5-20, preferably 1:10, the reaction temperature is 25-100°C, preferably 40°C, and the drying temperature is 25-100°C, preferably 60°C.

[0013] Furthermore, the calcium-based hydrotalcite (Ca-based LDH) is one of CaAl-NO3 and CaFe-NO3, preferably CaAl-NO3.

[0014] The composite mineralizer for treating sulfate saline-alkali land of the present invention can be used to treat sulfate saline-alkali land. When the composite mineralizer of the present invention is applied to sulfate saline-alkali land, the three components react with the anions and cations in the sulfate saline-alkali land respectively, thereby mineralizing SO4 2- and Na + , consuming OH - , that is, to reduce the salt and alkali content of sulfate saline-alkali land and realize saline-alkali land restoration.

[0015] The application of the composite mineralizer for treating sulfate saline-alkali land according to the present invention comprises the following steps:

[0016] Acid-modified calcium-montmorillonite (Ca-MMT) was applied to the sulfate-type saline-alkali soil to be remediated. The soil was then watered and gently turned until the acid-modified calcium-montmorillonite (Ca-MMT) was evenly mixed with the soil. On the 20th day, nitrate-intercalated calcium-based hydrotalcite (Ca-LDH) was added, and the soil was watered and gently turned until the nitrate-intercalated calcium-based hydrotalcite (Ca-LDH) was evenly mixed with the soil. On the 40th day, humic acid (HA) was added, watered, and the soil was gently turned until the humic acid (HA) was evenly mixed with the soil. It is worth noting that watering and gently turning the soil were required regularly throughout the process to ensure that the composite mineralizer was evenly mixed with the soil.

[0017] Furthermore, the mass ratio of the acid-modified calcium-montmorillonite (Ca-MMT) to the sulfate-type saline-alkali soil to be repaired is 0 to 10:100; the mass ratio of the nitrate-intercalated calcium-based hydrotalcite (Ca-based LDH) to the sulfate-type saline-alkali soil to be repaired is 0 to 10:100; and the mass ratio of the humic acid (HA) to the sulfate-type saline-alkali soil to be repaired is 0 to 10:100.

[0018] Preferably, the mass ratio of the acid-modified calcium-montmorillonite (Ca-MMT) to the sulfate-type saline-alkali soil to be repaired is 6:100; the mass ratio of the nitrate-intercalated calcium-based hydrotalcite (Ca-based LDH) to the sulfate-type saline-alkali soil to be repaired is 5:100; the mass ratio of the humic acid (HA) to the sulfate-type saline-alkali soil to be repaired is 4:100.

[0019] Compared with the prior art, the composite mineralizer of the present invention has the following beneficial effects:

[0020] (1) The composite mineralizer of the present invention can mineralize or consume excess SO4 in sulfate-type saline-alkali land 2- OH - and Na + , significantly reducing the salt and alkali content of sulfate saline-alkali land, and achieving the goal of saline-alkali land management.

[0021] (2) Compared with Ca-MMT, the acid-modified Ca-MMT in the present invention has a larger pore volume, a larger specific surface area, and a stronger adsorption capacity. In the process of treating sulfate saline-alkali land, the acid-modified Ca-MMT slowly releases Ca 2+ The formation of cation vacancies, through electrostatic attraction and cation exchange, the Na + Filled into the cation vacancies, thus achieving the restriction of salt; at the same time, the slow release of Ca 2+ It can promote the growth of plant roots.

[0022] (3) The Ca-based LDH in the present invention is easy to synthesize and can be used to convert SO4 into 2-3-phosphate dehydrogenase (LDH) by interlayer anion exchange and surface adsorption during the treatment of sulfate-type saline-alkali land. 2- Mineralization, at the same time, releases NO3 - It can act as nitrate nitrogen to promote plant growth.

[0023] (4) HA in the present invention can consume OH in sulfate saline-alkali land. - On the one hand, it can improve the soil's ability to retain water and fertilizer, and on the other hand, it can provide nutrients for plant growth.

[0024] (5) The composite mineralizer of the present invention has low cost and can achieve good sulfate saline-alkali land treatment effect in a short time. The product after mineralization is stable, no toxic substances are precipitated, and no secondary pollution is generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The remediation effect of sulfate saline-alkali soil with different (a) CaAl-NO3; (b) Ca-MMT and (c) HA addition amounts;

[0026] Figure 2 The restoration effect of sulfate saline-alkali soil under different mineralizer addition orders;

[0027] Figure 3 The growth conditions of pea seedlings in sulfate saline-alkali soil, repaired soil and normal soil respectively. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0029] The first aspect of the present invention provides a composite mineralizer for treating sulfate-type saline-alkali land, the composite mineralizer comprising component A, component B and component C; wherein the component A is acid-modified calcium-montmorillonite (Ca-MMT); the component B is nitrate-intercalated calcium-hydrotalcite (Ca-LDH), which is prepared by colloid milling; and the component C is humic acid (HA). When the composite mineralizer is applied to sulfate-type saline-alkali land, the acid-modified calcium-montmorillonite slowly releases Ca 2+ , promoting the growth of plant roots, and forming a cation defect structure, generating cation vacancies, and transferring Na + At the same time, Ca-based LDH can realize the removal of SO4 in sulfate-type saline-alkali land through interlayer anion exchange and surface adsorption. 2- The restricted area and the released NO3 - As nitrate nitrogen to promote plant growth. Adding HA can consume OH in the system. - , improve the soil's ability to retain water and fertilizer, and provide nutrients for plant growth. Then, in the entire repair process, SO4 2- and Na + Fixed, OH - consumption, significantly reducing salt and alkali content.

[0030] In some embodiments of the present invention, the acid-modified calcium montmorillonite (Ca-MMT) is calcium montmorillonite modified with dilute sulfuric acid, dilute hydrochloric acid or dilute nitric acid. During its preparation, the solid-liquid ratio of Ca-MMT to dilute sulfuric acid, dilute hydrochloric acid or dilute nitric acid solution is 1:5 to 20; the reaction temperature is 25 to 100°C; and the drying temperature is 25 to 100°C.

[0031] In some embodiments of the present invention, the Ca-based LDH is selected from CaAl-NO3 and CaFe-NO3, preferably CaAl-NO3.

[0032] In some embodiments of the present invention, the synthesis conditions of CaAl-NO3 include: the addition ratio of Ca(NO3)2·4H2O to Al(NO3)3·9H2O is 1-3:1-2, preferably 2:1. The alkali solution is selected from NaOH, KOH and NH3·H2O, preferably NaOH.

[0033] The second aspect of the present invention provides the use of the composite mineralizer in the treatment of sulfate saline-alkali land.

[0034] When the composite mineralizer of the present invention is applied to sulfate saline-alkali land, the three components react with the anions and cations in the sulfate saline-alkali land respectively, thereby achieving SO4 2- and Na + Mineralization, OH - The consumption of cationic acid-modified calcium-montmorillonite (Ca-MMT) slow-releases Ca 2+ The formation of cation vacancies, through electrostatic attraction and cation exchange, the Na + Fill into the cation vacancies, thus achieving the restriction of salt; the anion intercalation structure Ca-based LDH can transfer SO4 2- Mineralization; HA is responsible for consuming OH in the system - , reducing the alkali content of sulfate saline-alkali land.

[0035] The third aspect of the present invention provides a method for treating sulfate saline-alkali land using the composite mineralizer, comprising the following steps: applying component A, i.e., acid-modified calcium-montmorillonite (Ca-MMT), to the saline-alkali soil to be treated, adding water and lightly turning the soil to ensure that component A is evenly mixed with the soil; adding component B, i.e., nitrate-intercalated calcium-based hydrotalcite (Ca-based LDH) on the 20th day, adding water and lightly turning the soil to ensure that component B is evenly mixed with the soil; adding component C, i.e., humic acid (HA) on the 40th day, adding water and lightly turning the soil to ensure that component C is evenly mixed with the soil. Watering and lightly turning the soil are required to be regularly added throughout the process to ensure that the composite mineralizer is evenly mixed with the soil.

[0036] In some embodiments of the present invention, the mass ratio of the acid-modified calcium-montmorillonite (Ca-MMT) to the sulfate-type saline-alkali soil to be repaired is 0 to 10:100, preferably 6:100; the mass ratio of the CaAl-NO3 to the sulfate-type saline-alkali soil to be repaired is 0 to 10:100, preferably 5:100; the mass ratio of the HA to the sulfate-type saline-alkali soil to be repaired is 0 to 10:100, preferably 4:100.

[0037] The present invention will be described in detail below through examples.

[0038] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents and instruments used, if no manufacturer is specified, are commercially available conventional products.

[0039] Example 1: Preparation of acid-modified Ca-MMT

[0040] (1) Weigh a small amount of Ca-MMT ore and place it in a glass beaker. Add an appropriate amount of dilute sulfuric acid (commercially available 95-98% sulfuric acid diluted 100 times) at a solid-liquid ratio of 1:10, heat at 40°C and stir at 500 rpm overnight.

[0041] (2) The product was centrifuged, washed with deionized water and ethanol several times, dried in an oven at 60°C, ground into powder, and reserved for later use.

[0042] Example 2: Synthesis of CaAl-NO3

[0043] (1) Dissolve 5.67 g of Ca(NO3)2·4H2O and 4.50 g of Al(NO3)3·9H2O in 400 mL of deionized water. Mark this solution as solution A and keep it for future use.

[0044] (2) Dissolve 35.20 g of NaOH in 400 mL of deionized water and reserve the solution as solution B.

[0045] (3) Turn on the colloid mill power supply and adjust the speed to 4000 rpm. Quickly pour solutions A and B into the colloid mill. After reacting for 1 minute, collect the sample.

[0046] (3) The precipitate was collected by centrifugation and washed with de-CO2 water until the pH value of the sample was 7. The sample was placed in an oven at 60°C for 24 hours, ground into powder, and reserved for later use.

[0047] Test Example 1

[0048] (1) 10 g of sulfate-type saline-alkali soil sample was added to a plastic container, and then 0-0.65 g of acid-modified Ca-MMT obtained in Example 1, 0-0.55 g of CaAl-NO3 obtained in Example 2, and 0-0.45 g of HA were added respectively.

[0049] (2) A group without adding any mineralizer was set as the blank control.

[0050] (3) After thoroughly mixing the mineralizer with the soil, add 2.5 mL of deionized water to the mixture at a water-to-soil ratio of 1:4. Place the container near a window at room temperature to ensure adequate light and air circulation, and replenish deionized water promptly. After 160 days of reaction, remove a small amount of soil sample from the plastic container, measure the physical and chemical properties of the soil, and compare the remediation effects of various indicators under different mineralizer dosages.

[0051] (4) Three parallel experiments were performed simultaneously in each group of experiments.

[0052] Figure 1The restoration effect of sulfate saline-alkali soil under different addition amounts of three mineralizers. Figure 1 It can be seen from a that the initial sulfate saline-alkali soil SO4 2- and NO3 - The contents were 10.11 and 0.11 g / kg, respectively. With the increase of CaAl-NO3 addition, SO4 2- The content dropped rapidly, the downward trend was fast at first and then slowed down, and finally stabilized. - When the CaAl-NO3 addition amount is 5:100 (5wt%), the SO4 2- The content dropped to 1.53g / kg, NO3 - The content increased to 2.03g / kg. When CaAl-NO3 continued to increase to 5.5:100 (5.5wt%), SO4 2- The content changes little, considering SO4 2- and NO3 - The content of CaAl-NO3 is determined to be 5:100 (5wt%). Figure 1 As can be seen from b, the Na + and Ca 2+ The contents were 4.05 and 0.92 g / kg, respectively. With the increase of Ca-MMT dosage, Na + The content slowly decreased, Ca 2+ The content increased, and the overall change trend was relatively uniform. When the Ca-MMT addition was 6:100 (6wt%), the Na + The content dropped to 2.49g / kg, Ca 2+ When the Ca-MMT addition amount was increased to 6.5:100 (6.5wt%), Na + The content does not change much, so the optimal addition amount of Ca-MMT is selected as 6:100 (6wt%). Figure 1 As can be seen in Figure c, the initial pH value of the sulfate saline-alkali soil was 8.56. As the HA dosage increased, the soil pH continued to decrease. When the HA dosage was 4:100 (4 wt%), the soil pH dropped to 7.51, which is close to the normal soil pH value and can meet the treatment requirements. Therefore, the HA dosage was selected as 4:100 (4 wt%). Based on the above experimental results, the dosages of CaAl-NO3, Ca-MMT, and HA were selected as 5:100, 6:100, and 4:100, respectively.

[0053] Test Example 2

[0054] The amount of mineralizers added was fixed, and the effects of different addition orders of the three mineralizers on the remediation effect of sulfate saline-alkali soil were explored.

[0055] (1) Seven groups of experiments were conducted in the order of adding the three mineralizers in Table 1. To ensure the same repair time, group A added the three mineralizers at the same time on the 20th day, and group BG added them in the order shown in Table 1.

[0056] (3) After thoroughly mixing the mineralizer with the soil, add 2.5 mL of deionized water to the mixture at a water-to-soil ratio of 1:4. Place the container near a window at room temperature to ensure adequate light and air circulation, and replenish deionized water promptly. After 160 days of reaction, remove a small amount of soil sample from the plastic container, measure the physical and chemical properties of the soil, and compare the remediation effect.

[0057] (4) Three parallel experiments were performed simultaneously in each group of experiments.

[0058] Table 1 Addition order of the three mineralizers in experimental groups A-G

[0059]

[0060] Figure 2 The restoration effect of sulfate saline-alkali soil under different mineralizer addition orders. Figure 2 As shown in a, SO4 in groups B, C and D of AG group 2- The repair effect was significantly better than that of the other four groups, among which SO4 2- The repair effect is the best. Figure 2 As shown in b, Na in groups D and E in group AG + The repair effect was better than that of the other five groups, among which the Na + The repair effect is the best. As can be seen from 2c, the pH repair effect of the AG group is similar, indicating that the pH repair effect of different mineralizer addition orders on sulfate saline-alkali soil is not much different. 2- 、Na + Group D had better performance in terms of concentration and pH, so the order of adding mineralizers in the three groups was to add Ca-MMT first, then add CaAl-NO3 on the 20th day, and then add HA on the 40th day.

[0061] Test Example 3

[0062] (1) On the first day, add Ca-MMT at a mass ratio of 6:100 between the mineralizer and the sulfate-alkali soil to be treated. After thoroughly mixing the mineralizer and soil, add 2.5 mL of deionized water to the mixture at a water-to-soil ratio of 1:4. Place the container near a window at room temperature to ensure adequate light and air circulation, and replenish deionized water promptly.

[0063] (2) on the 20th day, CaAl-NO3 was added at a mass ratio of 5:100;

[0064] (3) On the 40th day, HA was added at a mass ratio of 4:100.

[0065] (4) After 160 days of reaction, the repaired sulfate saline-alkali soil was obtained. 120 g of sulfate saline-alkali soil, repaired soil, and normal soil were added to plastic containers for pea seedling cultivation experiments.

[0066] (5) To promote plant growth, 5 g of nutrient fertilizer and 20 mL of deionized water were added to each group. An appropriate amount of plump, similar-sized pea seedlings were sown into the above soil.

[0067] (6) Keep the soil moist and replenish water regularly. Two parallel experiments were conducted for each group. After sowing, the soil was placed in an intelligent artificial climate chamber with a temperature of 28 ± 5 °C, a relative humidity of 50 ± 10%, and a photoperiod of 12 h.

[0068] The growth of pea seedlings can be seen in Figure 3 Pea seedlings germinate in the unrepaired sulfate saline-alkali soil in about one week, and the final emergence rate is only 3%. After about two weeks, the plant height of the pea seedlings is much lower than that of the pea seedlings in normal soil. However, in the repaired sulfate saline-alkali soil, the pea seedlings germinate in about three days, which is similar to the germination time of pea seedlings in normal soil. The growth rate of pea seedlings is also close to that of normal soil. At one and two weeks, the plant height of pea seedlings is almost the same as that in normal soil, and the density of leaves is no different from that in normal soil. Therefore, it can be proved that the performance of the repaired sulfate saline-alkali soil is similar to that of normal soil, and it can maintain the normal germination and growth of pea seedlings, that is, the sulfate saline-alkali land has achieved a good repair effect.

[0069] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A composite mineralizer for treating sulfate saline-alkali land, characterized by: The composite mineralizer comprises component A, component B and component C; wherein the component A is acid-modified calcium-based montmorillonite; the component B is nitrate-intercalated calcium-based hydrotalcite; and the component C is humic acid.

2. The composite mineralizer for treating sulfate saline-alkali land according to claim 1, wherein: The acid-modified calcium-montmorillonite is calcium-montmorillonite modified by dilute sulfuric acid, dilute hydrochloric acid or dilute nitric acid.

3. The composite mineralizer for treating sulfate saline-alkali land according to claim 2, characterized in that: The solid-liquid ratio of the calcium-based montmorillonite to dilute sulfuric acid, dilute hydrochloric acid or dilute nitric acid is 1:5-20, the reaction temperature is 25-100°C, and the drying temperature is 25-100°C.

4. The composite mineralizer for treating sulfate saline-alkali land according to claim 3, characterized in that: The solid-liquid ratio of the calcium-montmorillonite to dilute sulfuric acid is 1:10, the reaction temperature is 40°C, and the drying temperature is 60°C.

5. The composite mineralizer for treating sulfate saline-alkali land according to claim 1, characterized in that: The calcium-based hydrotalcite is one of CaAl-NO3 and CaFe-NO3.

6. The use of a composite mineralizer for treating sulfate saline-alkali land according to any one of claims 1 to 5, characterized in that: Used to treat sulfate saline-alkali land.

7. The use of a composite mineralizer for treating sulfate saline-alkali land according to claim 6, characterized in that: The steps include: Acid-modified calcium-montmorillonite is applied to the sulfate saline-alkali soil to be repaired, and water is added and the soil is gently turned over until the acid-modified calcium-montmorillonite is evenly mixed with the soil; on the 20th day, nitrate-intercalated calcium-hydrotalcite is added, and water is added and the soil is gently turned over until the nitrate-intercalated calcium-hydrotalcite is evenly mixed with the soil; on the 40th day, humic acid is added, and water is added and the soil is gently turned over until the humic acid is evenly mixed with the soil.

8. The use of a composite mineralizer for treating sulfate saline-alkali land according to claim 7, characterized in that: During the whole process, water should be added regularly and the soil should be turned lightly to ensure that the compound mineralizer is evenly mixed with the soil.

9. The use of a composite mineralizer for treating sulfate saline-alkali land according to claim 7, characterized in that: The mass ratio of the acid-modified calcium-based montmorillonite to the sulfate-type saline-alkali soil to be repaired is 0 to 10:100; the mass ratio of the nitrate-intercalated calcium-based hydrotalcite to the sulfate-type saline-alkali soil to be repaired is 0 to 10:100; and the mass ratio of the humic acid to the sulfate-type saline-alkali soil to be repaired is 0 to 10:

100.

10. The use of a composite mineralizer for treating sulfate saline-alkali land according to claim 9, characterized in that: The mass ratio of the acid-modified calcium-based montmorillonite to the sulfate-type saline-alkali soil to be repaired is 6:100; the mass ratio of the nitrate-intercalated calcium-based hydrotalcite to the sulfate-type saline-alkali soil to be repaired is 5:100; and the mass ratio of the humic acid to the sulfate-type saline-alkali soil to be repaired is 4:100.

Images