Method for preparing saline-alkali soil conditioner from sulfuric-acid residues and application of saline-alkali soil conditioner

Abstract

The invention discloses a method for preparing a saline-alkali soil conditioner by using sulfuric-acid residue and application, the conditioner is prepared from the following components in parts by weight: 50-150 parts of modified sulfuric-acid residue, 5-50 parts of humic acid and 0.01-0.02 part of beneficial bacterium agent, the modified sulfuric-acid residue is obtained by acid leaching and reduction of sulfuric-acid residue, concentrated acid filtration and drying, and the pH value of the modified sulfuric-acid residue is 4.5. By adopting the conditioner and the application method, the quality of the saline-alkali soil can be effectively improved, the salt content and the pH value of the saline-alkali soil are reduced, and the aggregate content and the organic matter content are increased.

Description

Technical Field

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

[0002] At present, the commonly used methods for improving saline-alkali land are chemical improvement, physical improvement, hydraulic improvement and biological improvement. The use of these improvement methods can meet the needs of saline-alkali land improvement to a certain extent. However, the above methods have advantages and disadvantages. For example, although the method of washing salt by flooding with water can temporarily reduce the soil salinity in saline-alkali land, this method wastes a lot of water resources, and flooding can easily lead to the loss of organic matter and nutrients; in the biological improvement method, microbial fertilizer is a sustainable improvement measure, but there are problems such as low survival rate of bacteria in different external environments; single chemical improvement cannot achieve the purpose of increasing soil organic matter and reducing salt, and must be used together with other substances.

[0003] The patent with authorization announcement number CN101514290A discloses the use of artificially synthesized organic polymer polyacrylamide as a water-retaining material, which is mainly used for soil structure improvement. However, the use of such polymer materials can easily lead to poor water vapor circulation in the soil. The patent with authorization announcement number CN102925358B discloses the application of a microbial combination improver. The microbial preparation is mainly used to improve saline-alkali land by fermenting organic fertilizers, rather than directly acting on saline-alkali soil. In addition, the patent adds many types of bacteria, which are difficult to control and have high costs.

[0004] Sulfuric acid slag is a powdery waste residue produced when pyrite is used as raw material in the sulfuric acid industry to produce sulfuric acid. Since pyrite slag is mostly landfilled, it not only causes serious pollution to the environment, but also occupies land. Using this waste residue for saline-alkali land improvement can save costs on the one hand, and achieve the purpose of comprehensive utilization on the other hand. Summary of the invention

[0005] One of the problems to be solved by the present invention is to use Fe in solid waste sulfuric acid slag to solve the practical problems of poor soil structure, high salinity and pH, poor soil fertility, etc. in saline-alkali land. 2+ Oxidized to Fe 3+The cementation in the process forms a soil aggregate skeleton, improves the soil aggregate structure and provides sufficient water-salt channels, thereby improving the soil structure and reducing the salt content. The loose and porous characteristics of the soil skeleton and sulfate slag are then used to adsorb humic acid and beneficial bacteria in the pores, continuously increasing the soil organic matter content and improving fertility. At the same time, the rich SiO2 in the sulfate slag is used to immobilize the beneficial bacteria and maintain their vitality. In addition, the calcium sulfate in the sulfate slag can neutralize the alkaline substances in the soil, thereby lowering the pH value of the soil and improving the growth environment of plants.

[0006] The second problem to be solved by the present invention is to modify solid waste sulfuric acid slag for the first time and use it as a saline-alkali land soil conditioner, thereby broadening the application scope of sulfuric acid slag and achieving the purpose of comprehensive utilization of solid waste and turning waste into treasure.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: A saline-alkali land conditioner is composed of the following raw materials in parts by weight: 50-150 parts of modified sulfate slag, 5-50 parts of humic acid, and 0.01-0.02 parts of beneficial bacteria agent, wherein the modified sulfate slag is obtained by acid leaching the sulfate slag.

[0008] The modified sulfate slag is obtained by roasting pyrite to prepare sulfuric acid, drying the sulfate slag solid waste, grinding, and sieving to obtain powdered sulfate slag, mixing the sulfate slag with a sulfuric acid solution with a concentration of 10-30 wt.%, stirring and reacting at room temperature 15-30°C for 12-24 hours, filtering, dehydrating and drying to obtain crystals, and then grinding them into powder.

[0009] Further preferably, the conditioning agent is composed of the following raw materials in parts by weight: 100-140 parts of modified sulfate slag, 25-45 parts of humic acid, and 0.01-0.02 parts of beneficial bacteria agent, wherein the modified sulfate slag is obtained by acid leaching the sulfate slag, and the pH value is 4.5.

[0010] More preferably, the conditioner is composed of the following raw materials in weight fractions: 130 parts of modified sulfate slag, 45 parts of humic acid, and 0.02 parts of beneficial bacteria.

[0011] The total salt content of the soil used in the saline-alkali land conditioner ranges from 3‰ to 20‰.

[0012] When the total salt content of the saline-alkali land is 3‰-10‰, the conditioner is composed of the following raw materials in weight fractions: 100 parts of modified sulfate slag, 30 parts of humic acid, and 0.01 parts of beneficial bacteria.

[0013] When the total salt content of the saline-alkali land is 10‰-20‰, the conditioner is composed of the following raw materials in weight fractions: 130 parts of modified sulfate slag, 45 parts of humic acid, and 0.02 parts of beneficial bacteria.

[0014] A saline-alkali land conditioner prepared from sulphuric acid slag, wherein the total salt content of the saline-alkali land conditioner is in the range of 10‰-20‰, and the components are as follows: 130 parts of modified sulphuric acid slag, 45 parts of humic acid, and 0.02 parts of beneficial bacteria agent, wherein the modified sulphuric acid slag is obtained by acid leaching the sulphuric acid slag.

[0015] Further preferably, the modified sulfate slag is obtained by roasting pyrite to prepare sulfuric acid, and the sulfate slag solid waste is dried, ground, and passed through a 10-mesh sieve to obtain powdered sulfate slag, and the sulfate slag is mixed with a sulfuric acid solution with a concentration of 20 wt.% (ratio of 1:2, W:V), and stirred at room temperature 25°C for 18 hours to neutralize the alkaline components in the sulfate slag and enhance its regulating effect on the soil, and then filtered, dehydrated and dried to obtain crystals, which are then ground into powder.

[0016] Furthermore, the humic acid is in powder form after passing through a 100-mesh sieve, the humic acid dry weight content is ≥60 wt.%, the organic matter content is ≥70 wt.%, the moisture content is ≤10 wt.%, and the pH is 4-5.

[0017] Furthermore, the beneficial bacteria is a composite microbial agent mixed with multiple microbial agents, which at least contains Bacillus megaterium, Bacillus subtilis and nitrogen-fixing bacteria, with a total effective viable count of ≥50 billion / g, and a count of each effective bacteria of ≥10 billion / g. These beneficial bacteria coordinate and interact with each other to promote the decomposition of humic acid and the absorption of nutrients by crops, while secreting multiple enzymes, and combining with modified sulfate slag to promote the formation of a large agglomeration structure in the soil.

[0018] Further, as a preferred embodiment of the present invention, the beneficial bacteria is a composite microbial agent mixed with multiple microbial agents, and 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 in parts by weight. Further preferably, the beneficial bacteria agent is composed 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 purchased through commercial channels. For example, in one embodiment of the present invention, it is purchased from Yangzhou Herrick Biotechnology Co., Ltd., and the method of use is carried out according to known methods or methods recommended by merchants.

[0019] The present invention also provides a method for preparing the saline-alkali land conditioner described in the above technical solution, comprising the following steps: (1) After acid leaching of sulfuric acid residue, filtering, dehydrating and drying to obtain crystals, which are then ground into powder; (2) drying the humic acid, grinding it, and passing it through a 100-mesh sieve to obtain powdered humic acid; (3) The powders obtained in (1) and (2) are thoroughly mixed, and the bacterial powder is added and stirred to obtain a mixture; The present invention also provides a method for using the saline-alkali land conditioner to improve saline-alkali land: the conditioner is evenly spread into the soil, and the amount of the conditioner used is 200-600 kg / mu.

[0020] When the total salt content in the 0-20cm tillage layer of soil is 3‰-10‰, the amount of conditioner used is 200-400kg / mu; when the total salt content in the 0-20cm tillage layer of soil is 10‰-20‰, the amount of conditioner used is 400-600kg / mu.

[0021] Preferably, first loosen the 0-30 cm soil with a rotary tiller, then evenly spread the improver into the soil, mix it evenly with the 0-20 cm soil with a rotary tiller, and leave it for more than 15 days.

[0022] The invention has simple ingredients, simple raw material acquisition and low price. A large number of tests and application examples have proved that the average cost of the reagent per mu is 200-600 yuan. After 1-3 months of application, the salt content of saline-alkali land is reduced by 20%-40%, the pH value is reduced by 2%-7%, the macroaggregate structure is improved by 30%-60%, the organic matter is improved by 10%-20%, and the crop survival rate is more than 80%.

[0023] The present invention is the first to modify solid waste sulfuric acid slag for use as a soil conditioner for saline-alkali land, thereby broadening the application scope of sulfuric acid slag. The sulfuric acid slag is mainly composed of iron oxide and silicon dioxide (SiO2), and also contains rich elements such as calcium and sulfur. It is acidic and has a certain potential for improving soil. Sulfur slag is obtained after pyrite is roasted at about 900°C, so that the sulfuric acid slag has developed micropores and presents a honeycomb, impregnation and wrapping structure, which makes the sulfuric acid slag have a small bulk density, high porosity, easy water absorption, and loose texture. SiO2 in the sulfuric acid slag can be used as a material for immobilizing microbial cells. Compared with traditional organic carriers for immobilizing cells, the material based on SiO2 has high mechanical strength, good chemical stability, no toxic side effects, and has a controllable porous structure, which is conducive to the mass transfer of cells and provides a good microenvironment such as biological adaptability and hydrophilicity for microorganisms.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following advantages: (1) The conditioning agent of the present invention comprehensively utilizes the combined effects of physics, chemistry and biology to improve the quality of the slag, which is highly efficient and effective. 2+ Oxidized to Fe 3The process forms the soil aggregate skeleton, thereby increasing the number of soil aggregates and the content of large aggregates, significantly reducing the increase of soil salt due to capillary force migration, and reducing the soil salt content; after humic acid and beneficial bacteria are combined, they are filled in the iron skeleton of the soil. Beneficial bacteria quickly decompose humic acid to increase the organic matter content of the soil. At the same time, the enzymes secreted by beneficial bacteria combine with the aggregate particles formed by modified sulfate slag and humic acid, further increasing the content of large aggregates and reducing the salt content. The loose and porous characteristics of sulfate slag can adsorb humic acid and beneficial bacteria in the pores, and the rich SiO2 can achieve the effect of immobilizing beneficial bacteria. Calcium sulfate can neutralize alkaline substances in the soil and reduce the pH value of the soil.

[0025] (2) The modified sulfate slag, humic acid and beneficial bacteria used in the present invention are widely available, low-priced and will not cause secondary pollution to the environment. The use of sulfate slag can also improve the comprehensive utilization level of solid waste and turn waste into treasure.

[0026] (3) The present invention has conducted a large number of laboratory and field tests on the selection and dosage of the three materials, and has conducted rigorous analysis of the test results. On this basis, the component contents of the materials in soils with different salt contents are finally determined.

[0027] (4) The improver of the present invention has a simple application method and a short improvement period. After one month of application, the salinity of alkaline soil can be significantly reduced and the content of water-stable aggregates in the soil can be increased. DETAILED DESCRIPTION

[0028] The following specific embodiments are further explanations of the present invention, but the described embodiments are only a part of the embodiments of the present invention, and do not mean that the content of the present invention is limited to the scope of the examples given.

[0029] The beneficial bacteria used in the following examples are composed of Bacillus subtilis, Bacillus megaterium and Azotobacter rotundus (weight ratio is 25:25:20), and the above components are purchased from Yangzhou Herrenknecht Biotechnology Co., Ltd., and the bacterial powders are directly mixed according to the proportion before use.

[0030] Sulfuric acid slag is a solid waste obtained by roasting pyrite to prepare sulfuric acid. The sulphuric acid slag used in the following examples is produced in the production process of Anhui Tongling Sulfuric Acid Plant.

[0031] Example 1

[0032] The saline-alkali land conditioner of this embodiment includes the following components by weight: 130 parts of modified sulfate slag, 45 parts of humic acid, and 0.02 parts of beneficial bacteria.

[0033] The preparation method of the modified sulfate slag: The solid waste of sulfate slag is dried, ground, and passed through a 10-mesh sieve to obtain powdered sulfate slag, which is mixed with a 20wt.% sulfuric acid solution (ratio of 1:2, W:V), stirred and reacted at room temperature 25°C for 18 hours, filtered, dehydrated and dried to obtain crystals, which are then ground into powder.

[0034] The prepared modified sulfate slag has an iron content of 40 wt.%, and is a powder with a moisture content of 10 wt.%.

[0035] The humic acid is potassium humate with a humic acid content of ≥60 wt.%, wherein the organic matter content is ≥70 wt.%. (In this embodiment, potassium humate is purchased from Henan Xinlianxin Group) The beneficial bacteria are Bacillus subtilis, Bacillus megaterium and round brown nitrogen-fixing bacteria, the total effective live bacteria count is ≥50 billion / g, the number of each effective bacteria in the beneficial bacteria agent is ≥10 billion / g, and the weight ratio is 25:25:20.

[0036] The preparation of the conditioner comprises the following steps: (1) After drying the sulfuric acid slag powder, grind it with a roller and then pass it through a 10-mesh sieve. Humic acid is dried to a moisture content of ≤10wt.%, and then ground by a ball mill and then passed through a 100-mesh sieve.

[0037] (2) Add the sulfate slag powder, humic acid powder and bacterial powder into a blender and mix them evenly.

[0038] Comparative Example 1 The preparation of the saline-alkali land conditioner in this comparative example is the same as that in Example 1, except that the amount of sulfuric acid slag added is 65 parts; Comparative Example 2 The preparation of the saline-alkali land conditioner in this comparative example is the same as that in Example 1, except that the amount of sulfuric acid slag added is 260 parts; Comparative Example 3 The preparation of the saline-alkali land conditioner in this comparative example is the same as that in Example 1, except that no sulfuric acid slag is added; Comparative Example 4 The preparation of the saline-alkali land conditioner in this comparative example is the same as that in Example 1, except that no bacterial agent is added; Comparative Example 5 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; Comparative Example 6 This comparative example is blank soil.

[0039] The conditioners of Example 1 and Comparative Examples 1-6 were used to carry out improvement tests on severely saline-alkali barrier farmland on coastal tidal flats, as follows: (1) Basic information of the test site: The test site is located in Tongzhou Bay Reclamation Area, Nantong City, Jiangsu Province. The soil of the test site is sandy loam. The total salt content of the soil in the 0-20cm plough layer of the test site is 15.86-23.47‰, with an average content of 18.63‰, an average pH value of 8.40, an average organic matter of 3.33g / kg, a total nitrogen of 0.293 g / kg, an available potassium of 226mg / kg, and an available phosphorus of 3.70mg / kg. The average content of soil macroaggregates with a diameter of ≥0.25mm is 0.84%. The test site was divided into 6 areas of equal size, each with a size of 5m15m, and each area was separated by a 40cm deep and 30cm wide ditch.

[0040] (2) Test method: First, improve 6 areas, and use another area as the original soil control. Plow the soil 30 cm deep, then apply the improver prepared by the method of Example 1 and Comparative Examples 1-5 at a dosage of 600 kg per mu, plow 20 cm, and water thoroughly once and keep it for 30 days, and do a good job of drainage during the process. After the specified time, test various soil indicators. The specific results are shown in Table 1. The seventh saline-alkali land was used as a blank control, and no improver was added.

[0041] (3) Table 1 Various indicators of soil after improvement

[0042] From the above test results, it can be seen that the use of the conditioner and improvement method of the present invention can increase the aggregate content, improve the soil structure, and reduce the soil salt content and pH value, which is consistent with the goal of improving saline-alkali land.

Claims

1. A saline-alkali land conditioner, characterized in that: The conditioning agent is composed of the following raw materials in parts by weight: 50-150 parts of modified sulfate slag, 5-50 parts of humic acid, and 0.01-0.02 parts of beneficial bacteria agent, wherein the modified sulfate slag is obtained by acid leaching the sulfate slag.

2. A saline-alkali land conditioning agent according to claim 1, characterized in that: The modified sulfate slag is solid waste generated after sulfuric acid is produced from pyrite, which is crushed into granules or powder, and then mixed with a sulfuric acid solution with a concentration of 10-30 wt.%, filtered, dehydrated and dried after the reaction, wherein the mixing reaction of the sulfate slag and the sulfuric acid solution is carried out at room temperature, and the reaction time is 12-24 hours.

3. The saline-alkali land conditioning agent according to claim 1, characterized in that: The humic acid is in powder form after passing through a 100-mesh sieve, the humic acid dry weight content is ≥60 wt.%, the organic matter content is ≥50 wt.%, the moisture content is ≤10 wt.%, and the pH is 4-5.

4. A saline-alkali land conditioning agent according to claim 1, characterized in that: The beneficial bacteria are a composite bacterial agent formed by mixing multiple microbial agents. In parts by weight, the beneficial bacterial agent consists of 20-30 parts of Bacillus megaterium, 20-30 parts of Bacillus subtilis and 15-25 parts of nitrogen-fixing bacteria.

5. The saline-alkali land conditioning agent according to claim 1, characterized in that: The total salt content of the soil used in the saline-alkali land conditioner ranges from 3‰ to 20‰.

6. A saline-alkali land conditioning agent according to claim 4, characterized in that: The beneficial bacteria agent consists of 25 parts of Bacillus megaterium, 25 parts of Bacillus subtilis and 20 parts of nitrogen-fixing bacteria.

7. A saline-alkali land conditioning agent according to claim 5, characterized in that: When the total salt content of the saline-alkali land is 3‰-10‰, the conditioner is composed of the following raw materials in weight fractions: 100 parts of modified sulfate slag, 30 parts of humic acid, and 0.01 parts of beneficial bacteria.

8. A saline-alkali land conditioning agent according to claim 5, characterized in that: When the total salt content of the saline-alkali land is 10‰-20‰, the conditioner is composed of the following raw materials in weight fractions: 130 parts of modified sulfate slag, 45 parts of humic acid, and 0.02 parts of beneficial bacteria.

9. The method for preparing the sulfate slag saline-alkali land conditioner according to any one of claims 1 to 5, characterized in that: The steps are: (1) drying, grinding, and sieving the solid waste sulfuric acid slag obtained by roasting pyrite to prepare sulfuric acid to obtain powdered sulfuric acid slag, mixing the sulfuric acid slag with a sulfuric acid solution having a concentration of 10-30 wt.%, stirring and reacting at room temperature for 12-24 hours, filtering, dehydrating, and drying to obtain crystals, and then grinding them into powder; (2) drying, grinding, and sieving the humic acid to obtain powdered humic acid; (3) preparing the beneficial bacteria into powder; (4) The powders obtained in (1), (2) and (3) are thoroughly mixed and stirred to obtain a mixture.

10. The method for using the sulfate slag saline-alkali land conditioner according to any one of claims 1 to 5 for improving saline-alkali land, characterized in that: Sprinkle the conditioner evenly into the soil, the amount of conditioner used is 200-600kg / mu.

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