A method for repairing heavy metal pollution in saline-alkali soil by mineral fertilizer

Abstract

The invention discloses a method for repairing heavy metal pollution in saline-alkali soil by using mineral fertilizer, and relates to the technical field of soil pollution control; the method for repairing heavy metal pollution in saline-alkali soil by using mineral fertilizer of the invention is to apply mineral fertilizer to saline-alkali soil farmland, and mix it with soil by plowing and harrowing; wherein the mineral fertilizer includes waste hydrochloric acid, nitrogen fertilizer, phosphate fertilizer, potash fertilizer, Chinese medicine residue, and clay mineral; waste hydrochloric acid includes waste hydrochloric acid obtained after washing process in the process of preparing rutile by hydrochloric acid method; nitrogen fertilizer includes ammonium nitrate, sodium nitrate, and urea; the phosphate fertilizer includes diammonium phosphate; the Chinese medicine residue includes honeysuckle, Uncaria rhynchophylla, and toad venom; the clay mineral includes one or a mixture of two or more of kaolin, montmorillonite, illite, bentonite, talc, mica, vermiculite, chlorite, and sepiolite. The mineral fertilizer of the invention has a good repair effect on heavy metal polluted soil.

Description

Technical Field

[0001] The invention relates to the technical field of soil pollution control, and in particular to a method for repairing heavy metal pollution in saline-alkali soil by using mineral fertilizers. Background Art

[0002] Soil is the natural environment on which human beings depend for survival and the basic resource for agricultural production. Saline-alkali land is a type of salt accumulation, which refers to the land where the salt contained in the soil affects the normal growth of crops. Saline-alkali land can be divided into light saline-alkali land, moderate saline-alkali land and heavy saline-alkali land. The essence of its formation is mainly the horizontal and vertical redistribution of various soluble salts on the ground, so that salt gradually accumulates on the soil surface in the salt-collecting area. Some saline-alkali land is also contaminated by heavy metals. Due to the large-scale discharge of industrial "three wastes", farmland has suffered from heavy metal pollution to varying degrees, which not only directly affects the safety of agricultural products but also increasingly threatens the health and survival of animals and humans.

[0003] As we know, heavy metal pollution in soil refers to excessive content of elements such as mercury, cadmium, nickel, chromium, vanadium, arsenic, selenium, iron, manganese, copper, zinc, and lead in the soil. A considerable part of these are trace elements necessary for organisms, and some heavy metals are environmental pollutants. Currently, cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn) and mercury (Hg) are more studied. Since heavy metals are not easy to decompose, transform and enrich after entering the soil, and the structure of the soil system itself is complex, it is very difficult to control heavy metal pollution in soil. Therefore, there is an urgent need for a mineral fertilizer with better remediation effect on heavy metal contaminated soil to solve this problem. Summary of the invention

[0004] The purpose of the present invention is to provide a method for repairing heavy metal pollution in saline-alkali soil by using mineral fertilizers, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a mineral fertilizer, comprising, by weight: 13 to 25 parts of waste hydrochloric acid, 51 to 69 parts of nitrogen fertilizer, 26 to 34 parts of phosphate fertilizer, 13 to 17 parts of potash fertilizer, 60 to 90 parts of traditional Chinese medicine residues, and 90 to 120 parts of clay minerals.

[0006] Furthermore, the waste hydrochloric acid includes waste hydrochloric acid obtained after a washing process in a process for preparing rutile by a hydrochloric acid method, the hydrochloric acid concentration is 60-90 g / L, and the titanium content is 1-3 g / L.

[0007] Furthermore, the nitrogen fertilizer includes one or a mixture of two or more of ammonium nitrate, sodium nitrate and urea.

[0008] Furthermore, the phosphate fertilizer includes one of diammonium phosphate and phosphorus pentoxide, or a mixture of the two.

[0009] Furthermore, the traditional Chinese medicine residue includes one or a mixture of two or more of honeysuckle, Uncaria rhynchophylla and toad venom.

[0010] Furthermore, the clay mineral includes one or a mixture of two or more of kaolin, montmorillonite, illite, bentonite, talc, mica, vermiculite, chlorite and sepiolite.

[0011] The present invention provides a method for preparing a mineral fertilizer, comprising the following preparation steps:

[0012] (1) Ingredients: 13-25 parts by mass of waste hydrochloric acid, 51-69 parts by mass of nitrogen fertilizer, 26-34 parts by mass of phosphate fertilizer, 13-17 parts by mass of potash fertilizer, 60-90 parts by mass of traditional Chinese medicine residue, and 90-120 parts by mass of clay minerals;

[0013] (2) Primary mixing: 10-20 parts by weight of waste hydrochloric acid and 30-50 parts by weight of nitrogen fertilizer are mixed, stirred at 200-400 rpm for 30-50 min, then 60-90 parts by weight of Chinese medicinal residues and 32-48 parts by weight of dimethylformamide are added, stirred at 200-400 rpm for 1.5-2.5 h, then heated to 50° C., stirred at 200-400 rpm for 47-49 h, then heated to 153-155° C., kept warm at 10-20 Pa for 2-4 h, then cooled to 0-4° C. and frozen for 1-3 h, and continued to be frozen at -55--45° C. and 10-20 Pa for 24-26 h, taken out, ground, and sieved through a 200-300 mesh sieve to prepare a primary mixed material;

[0014] (3) Remixing: Mix the primary mixture obtained in step (2), 3-5 parts by weight of waste hydrochloric acid, 26-34 parts by weight of phosphate fertilizer, 13-17 parts by weight of potash fertilizer, and 90-120 parts by weight of clay mineral, and stir at 200-400 rpm for 4-6 hours to obtain a mineral fertilizer.

[0015] Furthermore, the nitrogen fertilizer comprises, by mass, 5 to 15 parts of ammonium nitrate, 26 to 34 parts of sodium nitrate, and 10 to 20 parts of urea.

[0016] The present invention also provides a method for repairing heavy metal pollution in saline-alkali soil with mineral fertilizers, and the specific steps are as follows: applying the mineral fertilizers to saline-alkali soil farmland, and mixing with the soil by plowing and harrowing.

[0017] Furthermore, the application amount of the mineral fertilizer is 100-300 kg / mu.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0019] The method for repairing heavy metal pollution in saline-alkali soil by using mineral fertilizer of the present invention comprises applying mineral fertilizer to saline-alkali soil farmland and mixing it with soil by plowing and harrowing; wherein the mineral fertilizer comprises waste hydrochloric acid, nitrogen fertilizer, phosphate fertilizer, potash fertilizer, Chinese medicine residue and clay mineral; the waste hydrochloric acid comprises waste hydrochloric acid obtained after washing process in the process of preparing rutile by hydrochloric acid method, wherein the concentration of hydrochloric acid is 60-90g / L; the nitrogen fertilizer comprises ammonium nitrate, sodium nitrate and urea; the phosphate fertilizer comprises diammonium phosphate; the Chinese medicine residue comprises honeysuckle, Uncaria rhynchophylla and toad venom; the clay mineral comprises one or a mixture of two or more of kaolin, montmorillonite, illite, bentonite, talc, mica, vermiculite, chlorite and sepiolite in any ratio.

[0020] Waste hydrochloric acid, nitrogen fertilizer and traditional Chinese medicine residue are introduced. The introduction of waste hydrochloric acid can neutralize saline-alkali soil well. At the same time, part of the hydrochloric acid in the waste hydrochloric acid reacts with part of the sodium nitrate in the nitrogen fertilizer to form sodium nitrite. The traditional Chinese medicine residues such as honeysuckle, Uncaria rhynchophylla and toad venom are rich in indole. Indole reacts with part of the hydrochloric acid and sodium nitrite in the waste hydrochloric acid to form 3-formyl indazole. 3-formyl indazole reacts with part of the amino group in the nitrogen fertilizer to form Schiff base. Indazole and Schiff base can passivate heavy metals in the soil, thereby enhancing the repair effect of mineral fertilizer on heavy metal contaminated soil. Porous clay minerals can quickly absorb passivated heavy metal elements, and replace the beneficial elements in the clay minerals through crystal substitution, completely fixing and sealing the heavy metal elements in the clay minerals, thereby further enhancing the repair effect of mineral fertilizer on heavy metal contaminated soil. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the various index testing methods of the mineral fertilizers prepared in the following examples as follows:

[0023] Heavy metal soil remediation: One acre of saline-alkali soil was taken and artificially polluted. The content of heavy metal Cd was 11.23 mg / kg. Mineral fertilizer was applied to the saline-alkali soil farmland and mixed with the soil by plowing and harrowing. The application amount of mineral fertilizer was 200 kg / acre. Appropriate amount of water was sprayed daily to achieve the purpose of moistening. After 30 days, samples were taken for testing and the fixation rate of heavy metal Cd was calculated. The fixation rate = 1-soil heavy metal content of the mineral fertilizer group / 11.23 mg / kg.

[0024] Example 1

[0025] A method for preparing a mineral fertilizer comprises the following preparation steps:

[0026] (1) Ingredients: 13 parts by mass of waste hydrochloric acid, 51 parts by mass of nitrogen fertilizer, 26 parts by mass of phosphate fertilizer, 13 parts by mass of potash fertilizer, 60 parts by mass of traditional Chinese medicine residue, and 90 parts by mass of clay mineral;

[0027] (2) Primary mixing: 10 parts by weight of waste hydrochloric acid and 30 parts by weight of nitrogen fertilizer were mixed, stirred at 200 rpm for 30 min, then 60 parts by weight of Chinese medicinal residue and 32 parts by weight of dimethylformamide were added, stirred at 200 rpm for 1.5 h, then heated to 50° C., stirred at 200 rpm for 47 h, then heated to 153° C., kept at 10 Pa for 2 h, then cooled to 0° C. and frozen for 1 h, and continued to be frozen at -55° C. and 10 Pa for 24 h, taken out, ground, and sieved through a 200-mesh sieve to prepare a primary mixed material;

[0028] (3) Remixing: The primary mixture obtained in step (2), 3 parts by weight of waste hydrochloric acid, 26 parts by weight of phosphate fertilizer, 13 parts by weight of potash fertilizer, and 90 parts by weight of clay mineral were mixed, and stirred at 200 rpm for 4 h to obtain a mineral fertilizer.

[0029] The nitrogen fertilizer comprises the following components by mass: 5 parts of ammonium nitrate, 26 parts of sodium nitrate, and 10 parts of urea.

[0030] The waste hydrochloric acid is waste hydrochloric acid obtained after a washing process in a rutile preparation process using a hydrochloric acid method, and the hydrochloric acid concentration is 60 g / L and the titanium content is 1 g / L.

[0031] The phosphate fertilizer comprises the following components by mass: 10 parts of diammonium phosphate and 16 parts of phosphorus pentoxide.

[0032] The traditional Chinese medicine residue comprises the following components by weight: 20 parts of honeysuckle, 20 parts of Uncaria rhynchophylla, and 20 parts of toad venom.

[0033] The clay mineral is 100 mesh montmorillonite.

[0034] Example 2

[0035] A method for preparing a mineral fertilizer comprises the following preparation steps:

[0036] (1) Ingredients: 19 parts by mass of waste hydrochloric acid, 60 parts by mass of nitrogen fertilizer, 30 parts by mass of phosphate fertilizer, 15 parts by mass of potash fertilizer, 70 parts by mass of traditional Chinese medicine residue, and 105 parts by mass of clay mineral;

[0037] (2) Primary mixing: 15 parts by weight of waste hydrochloric acid and 40 parts by weight of nitrogen fertilizer were mixed, stirred at 300 rpm for 40 min, then 70 parts by weight of Chinese medicinal residues and 40 parts by weight of dimethylformamide were added, stirred at 300 rpm for 2 h, then heated to 50°C, stirred at 300 rpm for 48 h, then heated to 154°C, kept at 15 Pa for 3 h, then cooled to 2°C and frozen for 2 h, and continued to be frozen at -50°C and 15 Pa for 25 h, taken out, ground, and sieved through a 250-mesh sieve to prepare a primary mixed material;

[0038] (3) Remixing: the primary mixture obtained in step (2), 4 parts by mass of waste hydrochloric acid, 30 parts by mass of phosphate fertilizer, 15 parts by mass of potash fertilizer, and 105 parts by mass of clay mineral are mixed, and stirred at 300 rpm for 5 hours to obtain mineral fertilizer; the 250-mesh primary mixture is wrapped and filled on the surface of the 150-mesh clay mineral. After the primary mixture passivates the heavy metals, the porous clay mineral can quickly absorb the passivated heavy metal elements, and replace the beneficial elements in the clay mineral through crystal replacement, so that the heavy metal elements are completely fixed and sealed in the clay mineral.

[0039] The nitrogen fertilizer comprises the following components by mass: 10 parts of ammonium nitrate, 30 parts of sodium nitrate, and 15 parts of urea.

[0040] The waste hydrochloric acid is the waste hydrochloric acid obtained after the washing process in the rutile preparation process using the hydrochloric acid method. The hydrochloric acid concentration is 70g / L and the titanium content is 2g / L. Titanium dioxide can be formed in the mineral fertilizer. The mineral fertilizer attached to the soil surface under light catalyzes the decomposition of traditional Chinese medicine residues to form fertilizer to provide nutrition for plants.

[0041] The phosphate fertilizer comprises the following components by mass: 12 parts of diammonium phosphate and 18 parts of phosphorus pentoxide.

[0042] The traditional Chinese medicine residue comprises the following components by weight: 25 parts of honeysuckle, 25 parts of Uncaria rhynchophylla, and 25 parts of toad venom.

[0043] The clay mineral is 150 mesh montmorillonite.

[0044] Example 3

[0045] A method for preparing a mineral fertilizer comprises the following preparation steps:

[0046] (1) Ingredients: 25 parts by mass of waste hydrochloric acid, 69 parts by mass of nitrogen fertilizer, 34 parts by mass of phosphate fertilizer, 17 parts by mass of potash fertilizer, 90 parts by mass of traditional Chinese medicine residue, and 120 parts by mass of clay mineral;

[0047] (2) Primary mixing: 20 parts by weight of waste hydrochloric acid and 50 parts by weight of nitrogen fertilizer were mixed, stirred at 400 rpm for 50 min, then 90 parts by weight of Chinese medicinal residues and 48 parts by weight of dimethylformamide were added, stirred at 400 rpm for 2.5 h, then heated to 50° C., stirred at 400 rpm for 49 h, then heated to 155° C., kept at 20 Pa for 4 h, then cooled to 4° C. and frozen for 3 h, and continued to be frozen at -45° C. and 20 Pa for 26 h, taken out, ground, and sieved through a 300-mesh sieve to prepare a primary mixed material;

[0048] (3) Remixing: The primary mixture obtained in step (2), 5 parts by weight of waste hydrochloric acid, 34 parts by weight of phosphate fertilizer, 17 parts by weight of potash fertilizer, and 120 parts by weight of clay mineral were mixed, and stirred at 400 rpm for 6 h to obtain a mineral fertilizer.

[0049] The nitrogen fertilizer comprises the following components by mass: 15 parts of ammonium nitrate, 34 parts of sodium nitrate, and 20 parts of urea.

[0050] The waste hydrochloric acid is waste hydrochloric acid obtained after a washing process in a rutile preparation process using a hydrochloric acid method, and the hydrochloric acid concentration is 90 g / L and the titanium content is 3 g / L.

[0051] The phosphate fertilizer comprises the following components by mass: 14 parts of diammonium phosphate and 20 parts of phosphorus pentoxide.

[0052] The Chinese medicinal residue comprises the following components by weight: 30 parts of honeysuckle, 30 parts of Uncaria rhynchophylla, and 30 parts of toad venom.

[0053] The clay mineral is 200 mesh montmorillonite.

[0054] Comparative Example 1

[0055] A method for preparing a mineral fertilizer comprises the following preparation steps:

[0056] (1) Ingredients: 19 parts by mass of waste hydrochloric acid, 60 parts by mass of nitrogen fertilizer, 30 parts by mass of phosphate fertilizer, 15 parts by mass of potash fertilizer, 70 parts by mass of traditional Chinese medicine residue, and 105 parts by mass of clay mineral;

[0057] (2) Primary mixing: 15 parts by weight of waste hydrochloric acid and 40 parts by weight of nitrogen fertilizer were mixed, stirred at 300 rpm for 40 min, then 70 parts by weight of Chinese medicinal residues and 40 parts by weight of dimethylformamide were added, stirred at 300 rpm for 2 h, then heated to 50°C, stirred at 300 rpm for 48 h, then heated to 154°C, kept at 15 Pa for 3 h, then cooled to 2°C and frozen for 2 h, and continued to be frozen at -50°C and 15 Pa for 25 h, taken out, ground, and sieved through a 250-mesh sieve to prepare a primary mixed material;

[0058] (3) Remixing: Mix the primary mixture obtained in step (2), 4 parts by mass of waste hydrochloric acid, 30 parts by mass of phosphate fertilizer, 15 parts by mass of potash fertilizer, and 105 parts by mass of clay mineral, and stir at 300 rpm for 5 h to obtain mineral fertilizer.

[0059] The nitrogen fertilizer comprises the following components by mass: 25 parts of ammonium nitrate and 30 parts of urea.

[0060] The waste hydrochloric acid is waste hydrochloric acid obtained after the washing process in the process of preparing rutile by the hydrochloric acid method, and the hydrochloric acid concentration is 70g / L and the titanium content is 2g / L.

[0061] The phosphate fertilizer comprises the following components by mass: 12 parts of diammonium phosphate and 18 parts of phosphorus pentoxide.

[0062] The traditional Chinese medicine residue comprises the following components by weight: 25 parts of honeysuckle, 25 parts of Uncaria rhynchophylla, and 25 parts of toad venom.

[0063] The clay mineral is 150 mesh montmorillonite.

[0064] Comparative Example 2

[0065] A method for preparing a mineral fertilizer comprises the following preparation steps:

[0066] (1) Ingredients: 19 parts by mass of waste hydrochloric acid, 60 parts by mass of nitrogen fertilizer, 30 parts by mass of phosphate fertilizer, 15 parts by mass of potash fertilizer, and 105 parts by mass of clay mineral;

[0067] (2) Primary mixing: 15 parts by mass of waste hydrochloric acid and 40 parts by mass of nitrogen fertilizer were mixed, stirred at 300 rpm for 40 min, then 40 parts by mass of dimethylformamide were added, stirred at 300 rpm for 2 h, then heated to 50° C., stirred at 300 rpm for 48 h, then heated to 154° C., kept at 15 Pa for 3 h, then cooled to 2° C. and frozen for 2 h, and continued to be frozen at -50° C. and 15 Pa for 25 h, taken out, ground, and passed through a 250-mesh sieve to prepare a primary mixed material;

[0068] (3) Remixing: Mix the primary mixture obtained in step (2), 4 parts by weight of waste hydrochloric acid, 30 parts by weight of phosphate fertilizer, 15 parts by weight of potash fertilizer, and 105 parts by weight of clay mineral, and stir at 300 rpm for 5 h to obtain mineral fertilizer.

[0069] The nitrogen fertilizer comprises the following components by mass: 10 parts of ammonium nitrate, 30 parts of sodium nitrate, and 15 parts of urea.

[0070] The waste hydrochloric acid is waste hydrochloric acid obtained after the washing process in the process of preparing rutile by the hydrochloric acid method, and the hydrochloric acid concentration is 70g / L and the titanium content is 2g / L.

[0071] The phosphate fertilizer comprises the following components by mass: 12 parts of diammonium phosphate and 18 parts of phosphorus pentoxide.

[0072] The clay mineral is 150 mesh montmorillonite.

[0073] Comparative Example 3

[0074] A method for preparing a mineral fertilizer comprises the following preparation steps:

[0075] (1) Ingredients: 19 parts by mass of waste hydrochloric acid, 60 parts by mass of nitrogen fertilizer, 30 parts by mass of phosphate fertilizer, 15 parts by mass of potash fertilizer, 70 parts by mass of traditional Chinese medicine residue, and 105 parts by mass of clay mineral;

[0076] (2) Primary mixing: 40 parts by weight of nitrogen fertilizer, 70 parts by weight of Chinese medicinal residue and 40 parts by weight of dimethylformamide were stirred at 300 rpm for 2 h, then heated to 50°C, stirred at 300 rpm for 48 h, then heated to 154°C, kept at 15 Pa for 3 h, then cooled to 2°C and frozen for 2 h, and then continued to be frozen at -50°C and 15 Pa for 25 h, taken out, ground, and passed through a 250-mesh sieve to prepare a primary mixture;

[0077] (3) Remixing: Mix the primary mixture obtained in step (2), 30 parts by weight of phosphate fertilizer, 15 parts by weight of potash fertilizer, and 105 parts by weight of clay mineral, and stir at 300 rpm for 5 h to obtain mineral fertilizer.

[0078] The nitrogen fertilizer comprises the following components by mass: 10 parts of ammonium nitrate, 30 parts of sodium nitrate, and 15 parts of urea.

[0079] The phosphate fertilizer comprises the following components by mass: 12 parts of diammonium phosphate and 18 parts of phosphorus pentoxide.

[0080] The traditional Chinese medicine residue comprises the following components by weight: 25 parts of honeysuckle, 25 parts of Uncaria rhynchophylla, and 25 parts of toad venom.

[0081] The clay mineral is 150 mesh montmorillonite.

[0082] Comparative Example 4

[0083] A method for preparing a mineral fertilizer comprises the following preparation steps:

[0084] (1) Ingredients: 19 parts by mass of waste hydrochloric acid, 60 parts by mass of nitrogen fertilizer, 30 parts by mass of phosphate fertilizer, 15 parts by mass of potash fertilizer, and 70 parts by mass of traditional Chinese medicine residue;

[0085] (2) Primary mixing: 15 parts by weight of waste hydrochloric acid and 40 parts by weight of nitrogen fertilizer were mixed, stirred at 300 rpm for 40 min, then 70 parts by weight of Chinese medicinal residues and 40 parts by weight of dimethylformamide were added, stirred at 300 rpm for 2 h, then heated to 50°C, stirred at 300 rpm for 48 h, then heated to 154°C, kept at 15 Pa for 3 h, then cooled to 2°C and frozen for 2 h, and continued to be frozen at -50°C and 15 Pa for 25 h, taken out, ground, and sieved through a 250-mesh sieve to prepare a primary mixed material;

[0086] (3) Remixing: Mix the primary mixture obtained in step (2), 4 parts by mass of waste hydrochloric acid, 30 parts by mass of phosphate fertilizer, and 15 parts by mass of potash fertilizer, and stir at 300 rpm for 5 h to obtain mineral fertilizer.

[0087] The nitrogen fertilizer comprises the following components by mass: 10 parts of ammonium nitrate, 30 parts of sodium nitrate, and 15 parts of urea.

[0088] The waste hydrochloric acid is waste hydrochloric acid obtained after the washing process in the process of preparing rutile by the hydrochloric acid method, and the hydrochloric acid concentration is 70g / L and the titanium content is 2g / L.

[0089] The phosphate fertilizer comprises the following components by mass: 12 parts of diammonium phosphate and 18 parts of phosphorus pentoxide.

[0090] The traditional Chinese medicine residue comprises the following components by weight: 25 parts of honeysuckle, 25 parts of Uncaria rhynchophylla, and 25 parts of toad venom.

[0091] Effect example

[0092] Table 1 below shows the results of heavy metal soil remediation performance analysis of mineral fertilizers prepared using Examples 1 to 3 of the present invention and Comparative Examples 1 to 4.

[0093] Table 1

[0094]

[0095] It can be found from Table 1 that the mineral fertilizers prepared in Examples 1, 2, and 3 have strong heavy metal soil remediation properties; from the comparison of the experimental data of Examples 1, 2, and 3 and Comparative Example 1, it can be found that the mineral fertilizer prepared using nitrogen fertilizer containing sodium nitrate has strong heavy metal soil remediation properties; from the experimental data of Examples 1, 2, and 3 and Comparative Example 2, it can be found that the mineral fertilizer prepared using Chinese medicine residue has strong heavy metal soil remediation properties; from the experimental data of Examples 1, 2, and 3 and Comparative Example 3, it can be found that the mineral fertilizer prepared using waste hydrochloric acid has strong heavy metal soil remediation properties; from the experimental data of Examples 1, 2, and 3 and Comparative Example 4, it can be found that the mineral fertilizer prepared using clay minerals has strong heavy metal soil remediation properties.

[0096] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing a mineral fertilizer for effectively fixing and sealing heavy metal Cd in saline-alkali land, characterized in that: The mineral fertilizer comprises, by weight: 13-25 parts of waste hydrochloric acid, 51-69 parts of nitrogen fertilizer, 26-34 parts of phosphate fertilizer, 13-17 parts of potash fertilizer, 60-90 parts of traditional Chinese medicine residue, and 90-120 parts of clay minerals; The nitrogen fertilizer comprises, by mass, 5-15 parts of ammonium nitrate, 26-34 parts of sodium nitrate and 10-20 parts of urea; The clay mineral includes montmorillonite; The Chinese medicine residues include honeysuckle, Uncaria rhynchophylla and toad venom; The waste hydrochloric acid includes waste hydrochloric acid obtained after the washing step in the hydrochloric acid process for preparing rutile, the hydrochloric acid concentration is 60-90g / L, the titanium content is 1-3g / L; The preparation method of the mineral fertilizer specifically comprises the following preparation steps: (1) Ingredients: 13-25 parts by weight of waste hydrochloric acid, 51-69 parts by weight of nitrogen fertilizer, 26-34 parts by weight of phosphate fertilizer, 13-17 parts by weight of potash fertilizer, 60-90 parts by weight of traditional Chinese medicine residue, and 90-120 parts by weight of clay mineral; (2) Primary mixing: 10-20 parts by weight of waste hydrochloric acid and 30-50 parts by weight of nitrogen fertilizer are mixed, stirred at 200-400 rpm for 30-50 min, then 60-90 parts by weight of Chinese medicinal residues and 32-48 parts by weight of dimethylformamide are added, stirred at 200-400 rpm for 1.5-2.5 h, then heated to 50° C., stirred at 200-400 rpm for 47-49 h, then heated to 153-155° C., kept warm at 10-20 Pa for 2-4 h, then cooled to 0-4° C. and frozen for 1-3 h, and continued to be frozen at -55--45° C. and 10-20 Pa for 24-26 h, taken out, ground, and sieved through a 200-300 mesh sieve to prepare a primary mixed material; (3) Remixing: Mix the primary mixture obtained in step (2), 3 to 5 parts by weight of waste hydrochloric acid, 26 to 34 parts by weight of phosphate fertilizer, 13 to 17 parts by weight of potash fertilizer, and 90 to 120 parts by weight of clay mineral, and stir at 200 to 400 rpm for 4 to 6 hours to obtain a mineral fertilizer; The phosphate fertilizer comprises one of diammonium phosphate and phosphorus pentoxide or a mixture of the two.

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