A method for preparing a conditioner for saline-alkali land from sulfuric acid residue and its application

Abstract

The present invention discloses a method for preparing a saline-alkali soil conditioner using sulfuric acid residue and its application. By weight, the formulation of the conditioner is as follows: 50-150 parts of modified sulfuric acid residue, 5-50 parts of humic acid, and 0.01-0.02 parts of beneficial bacteria agent. The modified sulfuric acid residue is obtained by acid leaching, reduction, filtration of concentrated acid, and drying of the sulfuric acid residue, and has a pH of 4.5. Using the conditioner and application method of the present invention can effectively improve the quality of saline-alkali soil, achieve the reduction of the salt content and pH value of saline-alkali soil, and increase the aggregate content and organic matter content.

Description

Technical Field

[0001] The present invention belongs to the technical field of saline-alkali land improvement, and particularly relates to the preparation and application of a conditioner for saline-alkali land, which is specifically aimed at improving the soil structure of saline-alkali land, reducing salinity and increasing soil organic matter. Background Art

[0002] Currently, the commonly used methods for saline-alkali land improvement include chemical improvement, physical improvement, hydraulic improvement and biological improvement methods. The use of these improvement methods to a certain extent meets the needs of saline-alkali land improvement. However, these methods have both advantages and disadvantages. For example, in the method of flooding for salt washing, although the soil salt content in saline-alkali land can be reduced for a while, this method wastes a large amount of water resources, and at the same time, the large amount of water is likely to cause the loss of organic matter and nutrients; in the biological improvement method, microbial fertilizers, as a sustainable improvement measure, have problems such as low survival rate of strains in different external environments; single chemical improvement cannot achieve the purpose of increasing soil organic matter and reducing salt content, and must be used together with other substances.

[0003] The patent with the authorization announcement number CN101514290A discloses the use of synthetic organic polymer polyacrylamide as a water-retaining material, which is mainly used for soil structure improvement. However, the use of such polymer materials easily causes poor water vapor circulation between soils; the patent with the authorization announcement number CN102925358B discloses the application of a microbial combination conditioner. This microbial preparation is mainly used for saline-alkali land improvement after fermenting organic fertilizers, rather than directly acting on saline-alkali land soil. Moreover, this patent adds a large number of bacterial species, which is not easy to control and has a high cost.

[0004] Sulfuric acid residue is a powdery waste residue generated during the production of sulfuric acid using pyrite as a raw material in the sulfuric acid industry. Since most sulfur iron residues are landfilled, it not only causes serious environmental pollution, but also occupies land for landfill. Using this waste residue for saline-alkali land improvement can not only save costs, but also achieve the purpose of comprehensive utilization. Summary of the Invention

[0005] One of the problems to be solved by the present invention is to utilize Fe in solid waste sulfuric acid residue in view of the practical problems such as poor soil structure, high salt content and pH value, and poor soil fertility in saline-alkali land 2+ oxidized to Fe 3+The cementation during the process forms the soil aggregate skeleton, improves the soil aggregate structure, and provides sufficient water and salt channels, thereby achieving the purpose of improving the soil structure and reducing salt content. Then, by utilizing the loose and porous characteristics of the soil skeleton and sulfuric acid residue, humic acid and beneficial bacteria are adsorbed in the pores, continuously increasing the soil organic matter content and improving fertility. At the same time, the SiO2 rich in the sulfuric acid residue is also used to immobilize the beneficial bacterial community and maintain the vitality of the beneficial bacteria. In addition, the calcium sulfate in the sulfuric acid residue can neutralize the alkaline substances in the soil, thereby reducing the pH value of the soil and improving the plant growth environment.

[0006] The second problem to be solved by the present invention is that the solid waste sulfuric acid residue is modified for the first time and used as a saline-alkali soil conditioner, thereby broadening the application range of the sulfuric acid residue and achieving the purpose of comprehensive utilization of solid waste and turning waste into treasure.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A saline-alkali soil conditioner, which is composed of the following raw materials by weight: 50 - 150 parts of modified sulfuric acid residue, 5 - 50 parts of humic acid, and 0.01 - 0.02 parts of beneficial bacteria agent, wherein the modified sulfuric acid residue is obtained by acid leaching treatment of sulfuric acid residue.

[0009] The modified sulfuric acid residue is obtained by drying, grinding, and sieving the sulfuric acid residue solid waste obtained after roasting pyrite to produce sulfuric acid to obtain powdery sulfuric acid residue. The sulfuric acid residue is mixed with a sulfuric acid solution with a concentration of 10 - 30 wt.%, stirred and reacted at room temperature of 15 - 30 °C for 12 - 24 hours, filtered, dehydrated, and dried to obtain crystals, and then ground into powder.

[0010] Further preferably, the conditioner is composed of the following raw materials by weight: 100 - 140 parts of modified sulfuric acid residue, 25 - 45 parts of humic acid, and 0.01 - 0.02 parts of beneficial bacteria agent, wherein the modified sulfuric acid residue is obtained by acid leaching treatment of sulfuric acid residue and has a pH of 4.5.

[0011] More preferably, the conditioner is composed of the following raw materials by weight fraction: 130 parts of modified sulfuric acid residue, 45 parts of humic acid, and 0.02 parts of beneficial bacteria.

[0012] The total salt content range of the soil where the saline-alkali soil conditioner is used is 3‰ - 20‰.

[0013] When the total salt content of the saline-alkali land is 3‰ - 10‰, the conditioner is composed of the following raw materials by weight fraction: 100 parts of modified sulfuric acid residue, 30 parts of humic acid, and 0.01 parts of beneficial bacteria.

[0014] When the total salt content of saline-alkali land is 10‰ - 20‰, the conditioner is composed of the following raw materials by weight fraction: 130 parts of modified sulfuric acid residue, 45 parts of humic acid, and 0.02 parts of beneficial bacteria.

[0015] A conditioner for saline-alkali land prepared from sulfuric acid residue, the total salt content range used in the conditioner for saline-alkali land is 10‰ - 20‰, by weight: 130 parts of modified sulfuric acid residue, 45 parts of humic acid, and 0.02 parts of beneficial bacteria agent, wherein the modified sulfuric acid residue is obtained after acid leaching treatment of sulfuric acid residue.

[0016] Further preferably, the modified sulfuric acid residue is obtained by drying, grinding, and passing through a 10-mesh sieve the sulfuric acid residue waste obtained after roasting pyrite to prepare sulfuric acid, to obtain powdery sulfuric acid residue, mixing the sulfuric acid residue with a sulfuric acid solution with a concentration of 20 wt.% (ratio 1:2, W:V), stirring and reacting at room temperature of 25°C for 18 hours to neutralize the alkaline components in the sulfuric acid residue and enhance its regulation effect on the soil, and then obtaining crystals after filtration, dehydration, and drying, and then grinding into powder.

[0017] Further, the humic acid passes through a 100-mesh sieve and is in powder form, the dry weight content of humic acid ≥ 60 wt.%, the organic matter content ≥ 70 wt.%, the moisture content ≤ 10 wt.%, and the pH is 4 - 5.

[0018] Further, the beneficial bacteria are a compound bacteria agent mixed by a variety of microbial bacteria agents, which at least includes Bacillus megaterium, Bacillus subtilis, and nitrogen-fixing bacteria, the total effective viable bacteria count ≥ 50 billion / g, and the number of each effective bacteria ≥ 10 billion / g. These beneficial bacteria coordinate and interact with each other, promote the decomposition of humic acid and the absorption of nutrient elements by crops, and at the same time secrete a variety of enzymes, and combine with the modified sulfuric acid residue to promote the formation of large aggregate structures in the soil.

[0019] Further, as a preferred embodiment of the present invention, the beneficial bacteria are a compound bacteria agent mixed by a variety of microbial bacteria agents, by weight, the beneficial bacteria agent consists of 20 - 30 parts of Bacillus megaterium, 20 - 30 parts of Bacillus subtilis, and 15 - 25 parts of nitrogen-fixing bacteria. Further preferably, the beneficial bacteria agent consists of 25 parts of Bacillus megaterium, 25 parts of Bacillus subtilis, and 20 parts of nitrogen-fixing bacteria. Bacillus megaterium, Bacillus subtilis, and nitrogen-fixing bacteria are all commonly used strains in the art and can be obtained through commercial channels. For example, in an embodiment of the present invention, they are purchased from Yangzhou Haierui Biotechnology Co., Ltd., and the usage method is carried out according to known methods or the methods recommended by the merchant.

[0020] The present invention also provides a preparation method of the conditioner for saline-alkali land described in the above technical solution, and the steps are:

[0021] (1) After acid leaching treatment of the sulfuric acid residue, filter, dehydrate, and dry to obtain crystals, and then grind into powder;

[0022] (2) Dry the humic acid, grind it, and sieve it through a 100-mesh sieve to obtain powdered humic acid;

[0023] (3) Thoroughly mix the powders obtained in (1) and (2), add the bacterial powder, and stir to obtain a mixture;

[0024] The present invention also provides a method for using the above-mentioned saline-alkali soil conditioner for improving saline-alkali soil: evenly sprinkle the conditioner into the soil, and the dosage of the conditioner is 200 - 600 kg / mu.

[0025] When the total salt content in the 0 - 20 cm plough layer soil is 3‰ - 10‰, the dosage of the conditioner is 200 - 400 kg / mu; when the total salt content in the 0 - 20 cm plough layer soil is 10‰ - 20‰, the dosage of the conditioner is 400 - 600 kg / mu.

[0026] Preferably, first loosen the 0 - 30 cm soil with a rotary tiller, then evenly sprinkle the conditioner into the soil, and use the rotary tiller to evenly mix it with the 0 - 20 cm soil, and let it stand for more than 15 days.

[0027] The composition of the present invention is simple, the raw materials are easily obtained and inexpensive. Proven by a large number of experiments and application examples, the average cost per mu of this reagent is 200 - 600 yuan. After 1 - 3 months of application, the salt content of the saline-alkali soil decreases by 20% - 40%, the pH value decreases by 2% - 7%, the large aggregate structure increases by 30% - 60%, the organic matter increases by 10% - 20%, and the crop survival rate is over 80%.

[0028] The present invention first uses the modified solid waste sulfuric acid residue as a saline-alkali soil conditioner, thereby broadening the application scope of sulfuric acid residue. The composition of sulfuric acid residue is mainly iron oxides and silicon dioxide (SiO₂), and also contains rich elements such as calcium and sulfur, showing acidity and having a certain potential for soil improvement. Sulfuric acid residue is obtained by roasting pyrite at about 900 °C, making the sulfuric acid residue have well-developed micropores, showing a honeycomb-like, disseminated and wrapped structure, which makes the sulfuric acid residue have a small bulk density, a high porosity, easy water absorption, and a loose texture. SiO₂ in the sulfuric acid residue can be used as a material for immobilizing microbial cells. Compared with the traditional organic carriers used for immobilizing cells, the SiO₂-based materials have high mechanical strength, good chemical stability, no toxic side effects, a controllable porous structure, which is conducive to cell mass transfer and provides a good microenvironment such as biological adaptability and hydrophilicity for microorganisms.

[0029] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0030] (1) The conditioner of the present invention comprehensively utilizes the combined effects of physics, chemistry and biology for improvement, with high efficiency and remarkable effects. In the modified sulfuric acid residue, Fe 2+Oxidized to Fe 3 The process of 3 forms the soil aggregate skeleton, thereby increasing the number of soil aggregates and the content of large aggregates, significantly reducing the upward migration of soil salts due to capillary force, and reducing the soil salt content; after the humic acid and beneficial bacteria are combined, they are filled in the iron skeleton of the soil, and the beneficial bacteria quickly decompose the humic acid to increase the soil organic matter content. At the same time, the enzymes secreted by the beneficial bacteria combine with the aggregate particles formed by the modified sulfuric acid residue and humic acid to further increase the content of large aggregates and reduce the salt content. The loose and porous characteristics of the sulfuric acid residue can adsorb humic acid and beneficial bacteria in the pores, and the rich SiO2 can play a role in immobilizing the beneficial bacterial flora. Calcium sulfate can neutralize the alkaline substances in the soil and reduce the pH value of the soil.

[0031] (2) The modified sulfuric acid residue, humic acid, and beneficial bacteria agent used in the present invention have a wide range of sources, low prices, and will not cause secondary pollution to the environment. The use of sulfuric acid residue can also improve the comprehensive utilization level of solid waste and turn waste into treasure.

[0032] (3) The present invention has carried out a large number of laboratory and field tests on the selection and dosage of the three materials, and rigorously analyzed the test results. On this basis, the component content of the materials in soils with different salt contents is finally determined.

[0033] (4) The application method of the improver of the present invention is simple, the improvement period is short, and the salt content of the alkaline soil can be significantly reduced and the content of water-stable aggregates in the soil can be increased one month after application. Detailed implementation mode

[0034] The following specific examples further illustrate the present invention, but the described examples are only a part of the examples of the present invention, and do not mean that the content of the present invention is limited to the scope of the examples cited.

[0035] The beneficial bacteria used in the following examples are composed of Bacillus subtilis, Bacillus megaterium, and Azotobacter chroococcum (weight ratio of 25:25:20). The above components are all purchased from Yangzhou Herike Biotechnology Co., Ltd., and the bacterial powder is directly mixed in proportion and used.

[0036] The sulfuric acid residue is the sulfuric acid residue solid waste obtained after roasting pyrite to prepare sulfuric acid. The sulfuric acid residue used in the following examples comes from the sulfuric acid residue generated during the production process of Anhui Tongling Sulfuric Acid Plant.

[0037] Example 1

[0038] The saline-alkali land conditioner of this example includes the following weight components: 130 parts of modified sulfuric acid residue, 45 parts of humic acid, and 0.02 parts of beneficial bacteria.

[0039] The preparation method of the modified sulfuric acid residue described:

[0040] The sulfuric acid residue solid waste is dried, milled, and sieved through a 10-mesh sieve to obtain powdered sulfuric acid residue. The sulfuric acid residue is mixed with a sulfuric acid solution with a concentration of 20 wt.% (ratio 1:2, W:V), and stirred at room temperature of 25 °C for 18 hours. After filtration, dehydration, and drying, crystals are obtained, and then milled into a powder.

[0041] The iron content in the prepared modified sulfuric acid residue is 40 wt.%, and it is a powder with a moisture content of 10 wt.%.

[0042] The humic acid is potassium humate with a humic acid content of ≥60 wt.%, and the organic matter content is ≥70 wt.%. (In this example, potassium humate is purchased from Henan Xinlianxin Group)

[0043] The beneficial bacteria are Bacillus subtilis, Bacillus megaterium, and Azotobacter chroococcum. The total effective viable bacteria count is ≥50 billion / g, and the number of each effective bacterium in the beneficial bacteria agent is ≥10 billion / g. Their weight ratio is 25:25:20.

[0044] The preparation of the conditioner includes the following steps:

[0045] (1) After drying the sulfuric acid residue powder, it is ground by a pair of rollers and all passed through a 10-mesh sieve. The humic acid is dried to a moisture content of ≤10 wt.%, ground by a ball mill, and all passed through a 100-mesh sieve.

[0046] (2) Add the sulfuric acid residue powder, humic acid powder, and bacterial powder to a blender respectively and mix and stir evenly.

[0047] Comparative Example 1

[0048] The preparation of the saline-alkali land conditioner in this comparative example is the same as that in Example 1, except that the addition amount of sulfuric acid residue is 65 parts;

[0049] Comparative Example 2

[0050] The preparation of the saline-alkali land conditioner in this comparative example is the same as that in Example 1, except that the addition amount of sulfuric acid residue is 260 parts;

[0051] Comparative Example 3

[0052] The preparation of the saline-alkali land conditioner in this comparative example is the same as that in Example 1, except that sulfuric acid residue is not added;

[0053] Comparative Example 4

[0054] The preparation of the saline-alkali land conditioner in this comparative example is the same as that in Example 1, except that the bacterial agent is not added;

[0055] Comparative Example 5

[0056] The preparation of the saline-alkali land conditioner in this comparative example is the same as that in Example 1, except that humic acid is not added;

[0057] Comparative Example 6

[0058] This comparative example is blank soil.

[0059] The conditioner of Example 1 and Comparative Examples 1-6 was used to conduct an improvement test on severely saline-alkali obstacle cultivated land in coastal tidal flats, as follows:

[0060] (1) Basic situation of the test plot: The test plot is located in the reclamation area of Tongzhou Bay, Nantong City, Jiangsu Province. The soil of the test plot is sandy loam. The total salt content of the 0-20 cm soil layer in the test plot is 15.86-23.47‰, with an average content of 18.63‰, the average pH value is 8.40, the average organic matter is 3.33 g / kg, the total nitrogen is 0.293 g / kg, the available potassium is 226 mg / kg, the available phosphorus is 3.70 mg / kg, and the average content of soil macro-aggregates with a diameter ≥ 0.25 mm is 0.84%. The test plot was divided into 6 areas of the same size, each with a size of 5m×5m, and each plot was separated by a ditch with a depth of 40 cm and a width of 30 cm.

[0061] (2) Test method: First, improve the 6 areas, and use another area as the original soil control. Deeply plow the soil by 30 cm, and then apply the modifiers prepared by the method of Example 1 and Comparative Examples 1-5 at a rate of 600 kg per mu, plow 20 cm, and at the same time pour enough water once and keep it for 30 days. Do a good job in drainage during the process. After the specified time, detect various soil indexes. The specific results are shown in Table 1. The 7th saline-alkali land is used as a blank control without adding any modifier.

[0062] (3) Table 1 Situation of various soil indexes after improvement

[0063]

[0064] From the above test results, it can be seen that using the conditioner and improvement method of the present invention can increase the aggregate content, improve the soil structure, reduce the soil salt content and pH value, which is consistent with the goal of saline-alkali land improvement.

Claims

1. A saline-alkali soil conditioner, characterized in that, The conditioner is composed of the following raw materials by weight: 50-150 parts of modified sulfuric acid residue, 5-50 parts of humic acid, and 0.01-0.02 parts of beneficial bacteria agent; wherein the modified sulfuric acid residue is obtained by acid leaching treatment of sulfuric acid residue, and the pH is 4.5; the modified sulfuric acid residue is a solid waste generated after pyrite is used to produce sulfuric acid, which is crushed into granular or powdery form, and then mixed with a sulfuric acid solution with a concentration of 10-30 wt.%, reacted at room temperature for 12-24 hours, and obtained by filtration, dehydration and drying; the beneficial bacteria agent is composed of 20-30 parts of Bacillus megaterium, 20-30 parts of Bacillus subtilis and 15-25 parts of nitrogen-fixing bacteria.

2. The saline-alkali soil conditioner according to claim 1, wherein The humic acid passes through a 100-mesh sieve and is in powder form, the dry weight content of humic acid is ≥60 wt.%, the organic matter content is ≥50 wt.%, the moisture content is ≤10 wt.%, and the pH is 4-5.

3. The saline-alkali soil conditioner according to claim 1, wherein The applicable soil total salt content range of the saline-alkali land conditioner is 3‰-20‰.

4. The saline-alkali soil conditioner according to claim 1, wherein The beneficial bacteria agent is composed of 25 parts of Bacillus megaterium, 25 parts of Bacillus subtilis and 20 parts of nitrogen-fixing bacteria.

5. The soil conditioner for saline-alkali land according to claim 3, characterized in that, When the soil total salt content is 3‰-10‰, the conditioner is composed of the following raw materials by weight: 100 parts of modified sulfuric acid residue, 30 parts of humic acid, and 0.01 part of beneficial bacteria agent.

6. The saline-alkali soil conditioner according to claim 3, wherein When the soil total salt content is 10‰-20‰, the conditioner is composed of the following raw materials by weight: 130 parts of modified sulfuric acid residue, 45 parts of humic acid, and 0.02 part of beneficial bacteria agent.

7. The preparation method of the sulfuric acid residue saline-alkali land conditioner according to any one of claims 1 to 4, characterized in that, The steps are as follows: (1) Dry, grind and sieve the sulfuric acid residue solid waste obtained after roasting pyrite to produce sulfuric acid to obtain powdery sulfuric acid residue. Mix the sulfuric acid residue with a sulfuric acid solution with a concentration of 10-30 wt.%, stir and react at room temperature for 12-24 hours, filter, dehydrate and dry to obtain crystals, and then grind them into powder form; (2) Dry, grind and sieve the humic acid to obtain powdery humic acid; (3) Prepare the beneficial bacteria into powder; (4) Thoroughly mix and stir the powders obtained in (1), (2) and (3) to obtain a mixture.

8. The method of using the sulfuric acid residue saline-alkali land conditioner according to any one of claims 1-4 for improving saline-alkali land, characterized in that, Evenly sprinkle the conditioner into the soil, and the usage amount of the conditioner is 200-600 kg / mu.

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