Artificial soil based on neutralization residue improvement and preparation method thereof

Abstract

The invention provides artificial soil based on neutralization residue improvement and a preparation method thereof, and relates to the technical field of mine ecological environment restoration and treatment. According to the preparation method, a large amount of neutralization slag generated by neutralization treatment of acid wastewater is used as a main raw material, and a biochemical repair material, a water-retaining agent, an alkalinity regulator and an organic fertilizer are added to preliminarily improve the pH, nutritional ingredients, granular structures and other physicochemical properties of the tailings. On the basis, functional microorganisms are applied to form a granular structure, fix heavy metals and form a primary soil-like matrix, the microorganisms obtain nutrients and energy required by growth, humus is formed after microbial decomposition, plant absorption is promoted, meanwhile, the heavy metals are fixed in tailings, and the toxic action of the effective heavy metals on plants is reduced. The prepared artificial soil can be used for re-greening of tailings ponds, stope slopes, barren rock yards and the like of non-ferrous metal mines, the limitation that in-situ remediation is mostly adopted in the prior art is solved, and the application range is wide.

Description

Technical Field

[0001] The invention relates to the technical field of mine ecological environment restoration and management and the technical field of comprehensive utilization of bulk solid waste, and in particular to an artificial soil improved by neutralization slag and a preparation method thereof. Background Art

[0002] At present, acidic water in non-ferrous metal mines is generally treated with lime. After the acid-base neutralization reaction, a yellow semi-solid neutralized slag is produced, the main component of which is calcium sulfate, as well as other trace elements such as copper, lead, zinc, arsenic, cadmium, and mercury.

[0003] At present, the ecological restoration of non-ferrous metal mines mostly adopts the method of covering with soil and vegetation restoration. This method is highly applicable and suitable for the ecological restoration of most metal tailings wastelands. However, this ecological restoration method first requires the consumption of a large amount of high-quality soil sources, which is easy to cause secondary ecological damage to the surrounding environment and is not conducive to the sustainable development of enterprises. Most non-ferrous metal mines in my country have the problem of shortage of "foreign soil" resources, especially the fragile ecological environment and extremely scarce soil resources. The need to purchase soil for restoration has become a serious bottleneck restricting the quality of land reclamation in the region. The particle size of neutralized slag is similar to that of soil. After the improvement of alkalinity, nutrients, aggregate structure, water retention, and microecological environment, it can become a potential soil source.

[0004] In the prior art, the patent with publication number CN115606476A discloses a neutralized slag-based culture matrix and its preparation method and application. Neutralized slag, organic matter, plant fiber, water retaining agent, fertilizer, water, and pelleting promoter are mixed in a certain proportion to form a neutralized slag-based culture matrix. The patent uses neutralized slag as a "guest soil" material, but only mixes the neutralized slag with conventional materials, and fails to pay attention to the impact of microecological environment improvement on plant growth.

[0005] The patent with publication number CN116711495A discloses a method for ecological restoration using neutralized slag. After the neutralized slag is evenly mixed with microbial agents and nutrients, it is laid on the surface of the acidic medium layer of the mine to form a neutralized slag isolation layer, on which a waste rock isolation layer, a planting matrix, a vegetation growth layer, and an ecological restoration protection layer are sequentially arranged to achieve ecological restoration of the waste rock field and resource utilization of neutralized slag. However, the microbial agent used in this patent is sulfate-reducing bacteria, which has a single strain and cannot coordinate nitrogen fixation, phosphorus solubilization, potassium solubilization and other functions to achieve comprehensive regulation of the microecological environment. At the same time, this patent is only applicable to in-situ restoration, and the productization of artificial soil of neutralized slag has not been realized, and the application scenarios are limited. Summary of the invention

[0006] In view of the defects of the above-mentioned prior art, the purpose of the present invention is to provide an artificial soil based on neutralization slag improvement and a preparation method thereof. The preparation method uses a large amount of neutralization slag produced by the neutralization treatment of acidic wastewater as the main raw material, adds other ingredients, improves the physical, chemical and soil biological properties of the neutralization slag, and produces an artificial soil based on neutralization slag improvement, which is used for the tailings pond, mining slope, waste rock field greening of non-ferrous metal mines, etc., to achieve comprehensive benefits such as improving the mine environment, protecting precious soil resources, reducing solid waste storage, and improving the utilization rate of bulk solid waste resources.

[0007] To achieve the above object, the present invention provides a method for preparing artificial soil based on neutralized slag modification, comprising the following steps:

[0008] S1, screening of neutralization residue: using a vibrating screen to classify the solid particles of the sludge underflow generated by the acid water neutralization treatment, and separating the fine particles into neutralization residue powder with a particle size greater than 0.075 mm, a mass not exceeding 50% of the total mass, a moisture content not exceeding 20%, and a plasticity index not exceeding 10 for standby use;

[0009] S2, preparation of biochemical repair materials:

[0010] Powder: The agricultural waste is initially crushed into a powder with a particle size of ≤200mm and the moisture content is controlled between 40% and 60%;

[0011] Puffing: Add the powdered agricultural waste into the puffing machine, the puffing temperature is between 100℃ and 150℃, the puffing pressure is between 1.0MPa and 1.5MPa, the puffing time is between 0.25h and 2h, and the filaments with a length of about 50-100mm and a width of 1-2mm are formed;

[0012] Composting: Make an arched pile with a length of 1.5m to 3m and a width of 0.75m to 1.5m. Cover the top of the arched pile with film, keep the temperature between 40℃ and 60℃, ferment for 15 to 30 days, spray water regularly to keep the moisture content between 60% and 70%, and turn the pile every 5 to 10 days;

[0013] The fermentation product is air-dried in a cool and ventilated place, and the moisture content after air-drying is 5% to 15%, and crushed into powder with a particle size of ≤1mm;

[0014] S3, preparation of organic fertilizer: mixing air-dried cow dung and sheep dung in a mass ratio of 1:1 and crushing them, adding actinomycetes and Trichoderma, fermenting and composting to form organic fertilizer for standby use;

[0015] S4, microbial agent preparation process:

[0016] Preparation of culture medium: glucose 0.9g / L, ammonium chloride 1.0g / L, sodium chloride 10g / L, magnesium sulfate 2.1g / L, ferrous sulfate 0.1g / L, lactic acid 0.1g / L. According to the formula, various components are weighed and dissolved in water and added into the culture barrel. Sulfate-reducing bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, potassium-solubilizing bacteria, and Bacillus subtilis powder are added into the culture barrel. Closed culture is performed. When the liquid culture medium turns completely black, the culture is completed.

[0017] S5, modification of neutralized slag:

[0018] Weigh the neutralization slag, biochemical remediation materials, water retaining agent, alkalinity regulator and organic fertilizer according to the mass ratio at room temperature, add them into a blender and stir for 5 to 10 minutes to mix the various materials evenly, spread them on the outdoor anti-seepage site and spray them with microbial agents. The spraying frequency is once every three days and the spraying amount is 10L / t of neutralization slag. Naturally cure at room temperature for 15 days, and pack the above-mentioned evenly mixed materials in bags to form a neutralization slag soil product.

[0019] As a further improvement of the present invention, in step S5, the mass ratio refers to: 100 parts of neutralized slag, 5-10 parts of biochemical remediation materials, 0.05-0.1 parts of water retaining agent, 0.01-0.03 parts of alkalinity regulator, 5-10 parts of organic fertilizer, and 1.0 part of microbial agent; the microbial agent is a mixture of sulfate-reducing bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, potassium-solubilizing bacteria, and Bacillus subtilis in a mass ratio of 1:1:1:1:1.

[0020] To achieve the above object, the present invention further provides an artificial soil improved by neutralization slag, which is prepared by the above preparation method and comprises the following components by weight: 100 parts of neutralization slag, 5-10 parts of biochemical remediation materials, 0.05-0.1 parts of water retaining agent, 0.01-0.03 parts of alkalinity regulator, 5-10 parts of organic fertilizer, and 1.0 part of microbial agent; the microbial agent is a mixture of sulfate-reducing bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, potassium-solubilizing bacteria, and Bacillus subtilis in a mass ratio of 1:1:1:1:1.

[0021] Sulfate-reducing bacteria can use organic matter on the metal surface as a carbon source, and use the hydrogen produced in the bacterial biofilm to reduce sulfate to hydrogen sulfide, which reacts with heavy metal ions to form precipitates, reducing the toxicity and mobility of heavy metal ions and reducing the biological toxicity of the neutralized slag.

[0022] As a further improvement of the present invention, the mass of particles with a particle size greater than 0.075 mm in the neutralized slag does not exceed 50% of the total mass; the mass fraction of calcium sulfate in the neutralized slag is 70-75%, the mass fraction of trace elements is 0.4-0.6%, and the moisture content is less than or equal to 20%; the trace elements are one or more of lead, zinc, arsenic, cadmium, and mercury.

[0023] As a further improvement of the present invention, the neutralized slag meets the requirements of Class I general industrial solid waste. That is, the concentration of any pollutant in the leaching solution obtained by subjecting the neutralized slag to a leaching test according to the method specified in GB5086 does not exceed the maximum allowable emission concentration of GB8978, and the pH value is within the range of 6 to 9.

[0024] As a further improvement of the present invention, the biochemical repair material is a product of agricultural waste after powdering, puffing and composting, with a dark brown appearance, a particle size of ≤1 mm, a pH of 6.5-7.0, and a specific gravity of 0.6-0.7 g / cm 3 ; On a dry basis, the organic matter content is ≥45%, the nutrient content (N, P, K) is ≥3%, and the humic acid content is ≥20%; the agricultural waste is one or more of corn straw, rice husk, and sugarcane bagasse.

[0025] The biochemical repair material has a loose texture, large porosity, and low specific gravity, and has a strong alkalinity regulation and nutrient improvement effect. At the same time, the organic cementing substances produced by the decomposition of humic acid in the biochemical repair material have moderate cohesiveness, which can make the neutralization slag particles bond, further promote the agglomeration of the neutralization slag particles and the formation of large-size aggregates, effectively increase the content of water-stable aggregates in the neutralization slag, and have a certain fixation effect on water and nutrients.

[0026] As a further improvement of the present invention, the water retaining agent comprises 88%-90% potassium polyacrylate, 8%-10% water, and 0.5%-1.0% cross-linking agent. The water retaining agent is in the form of white powder and is a functional polymer material containing strong hydrophilic groups and having a certain degree of cross-linking. The water retaining agent is conducive to soil ventilation, has good reversibility of water absorption and release, can improve soil structure, and can promote the development of soil microorganisms and improve the turnover efficiency of soil organic matter.

[0027] As a further improvement of the present invention, the alkalinity regulator is potassium humate. The molecular formula is C3H5OS2K, the solution is slightly acidic, and the pH value is usually between 4.0-6.0. It can adjust the neutralization slag alkalinity, improve the soil aggregate structure, loosen the soil, increase the soil's water and fertilizer retention capacity, reduce the content of heavy metals in the soil, fix nitrogen, dissolve phosphorus, and activate potassium.

[0028] As a further improvement of the present invention, the organic fertilizer is a mixture of cow dung and sheep dung fermented and decomposed in a mass ratio of 1:1, and an organic fertilizer fermentation agent is added to form a fine powder organic fertilizer after fermentation and decomposition. The main species contained in the organic fertilizer fermentation agent are actinomycetes, Trichoderma, etc. The organic fertilizer after fermentation and decomposition is loose in nature, has no bad smell, has an organic matter content of ≥60% (on a dry basis), has an effective viable count of ≥20 million / g, and has a moisture content of ≤30%.

[0029] The beneficial effects of the present invention are:

[0030] 1. The entire neutralized slag modification process of the present invention is a process of physical and chemical property improvement and synergistic action of functional microorganisms. Biochemical repair materials, water retaining agents, alkalinity regulators, and organic fertilizers preliminarily improve the physical and chemical properties of tailings such as pH, nutrients, and aggregate structure. On this basis, functional microorganisms are applied to form aggregate structures and fix heavy metals to form a primary soil-like matrix. Microorganisms obtain the nutrients and energy required for growth, and humus is formed after microbial decomposition to promote plant absorption. At the same time, heavy metals are fixed in tailings to reduce the toxic effects of effective heavy metals on plants.

[0031] 2. The present invention is based on the actual situation of non-ferrous mines, adheres to the concept of "turning waste into treasure", takes a large amount of neutralization slag produced by the neutralization treatment of acidic wastewater as the main raw material, adds other improved components, and utilizes the complementary physical and chemical properties between different improved matrices and the neutralization slag to improve the physical, chemical and soil biological properties of the neutralization slag, thereby preparing an artificial soil improved by neutralization slag, which is used for the greening of tailings ponds, mining slopes and waste rock dumps of non-ferrous metal mines. On the one hand, it alleviates the storage capacity pressure caused by the storage of neutralization slag, and on the other hand, it can alleviate the problem of shortage of "foreign soil" for ecological restoration in ecologically fragile areas, and has broad application prospects.

[0032] 3. The method for preparing artificial soil based on neutralized slag improvement provided by the present invention is simple to operate, safe and reliable, and can not only improve the mine environment, but also protect precious soil resources, reduce solid waste storage, and improve the utilization rate of bulk solid waste resources, thus having significant environmental and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a comparison diagram of the planting effects of the artificial soil improved with neutralized slag according to the present invention and the unimproved neutralized slag.

[0034] Figure 2 This is a comparison diagram of the planting effects of the artificial soil improved by neutralized slag and the natural soil of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0037] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0038] The present invention provides a method for preparing artificial soil improved by neutralization slag, comprising the following steps:

[0039] S1, screening of neutralization residue: using a vibrating screen to classify the solid particles of the sludge underflow generated by the acid water neutralization treatment, and separating the fine particles into neutralization residue powder with a particle size greater than 0.075 mm, a mass not exceeding 50% of the total mass, a moisture content not exceeding 20%, and a plasticity index not exceeding 10 for standby use;

[0040] Among them, neutralized slag is produced by the acidic lime neutralization process in non-ferrous metal mines. The main component is about 75% calcium sulfate, and other trace elements such as lead, zinc, arsenic, cadmium, mercury, etc. are about 0.5%.

[0041] In addition, the neutralized slag meets the requirements of Class I general industrial solid waste. That is, the concentration of any pollutant in the leaching solution obtained by subjecting the neutralized slag to a leaching test according to the method specified in GB5086 does not exceed the maximum allowable emission concentration in GB8978, and the pH value is within the range of 6 to 9.

[0042] S2, preparation of biochemical repair materials:

[0043] Powder: The agricultural waste is initially crushed into a powder with a particle size of ≤200mm and the moisture content is controlled between 40% and 60%;

[0044] Puffing: Add the powdered agricultural waste into the puffing machine, the puffing temperature is between 100℃ and 150℃, the puffing pressure is between 1.0MPa and 1.5MPa, the puffing time is between 0.25h and 2h, and the filaments with a length of about 50-100mm and a width of 1-2mm are formed;

[0045] Composting: Make an arched pile with a length of 1.5m to 3m and a width of 0.75m to 1.5m. Cover the top of the arched pile with film, keep the temperature between 40℃ and 60℃, ferment for 15 to 30 days, spray water regularly to keep the moisture content between 60% and 70%, and turn the pile every 5 to 10 days;

[0046] The fermentation product is air-dried in a cool and ventilated place. After air-drying, the moisture content is 5% to 15%, and the product is crushed into powder with a particle size of ≤1mm.

[0047] Agricultural waste includes corn stalks, rice husks, sugarcane bagasse, etc.

[0048] S3, preparation of organic fertilizer: mixing air-dried cow dung and sheep dung in a mass ratio of 1:1 and crushing them, adding actinomycetes and Trichoderma, fermenting and composting to form organic fertilizer for standby use;

[0049] Organic fertilizer is a mixture of cow dung and sheep dung fermented in a mass ratio of 1:1. Organic fertilizer fermentation agents are added to form fine powder organic fertilizer after fermentation. The main species of organic fertilizer fermentation agents are actinomycetes, Trichoderma, etc. The organic fertilizer after fermentation is loose, without bad smell, with an organic matter content of ≥60% (on a dry basis), an effective live bacteria count of ≥20 million / g, and a moisture content of ≤30%.

[0050] S4, microbial agent preparation process:

[0051] Preparation of culture medium: glucose 0.9g / L, ammonium chloride 1.0g / L, sodium chloride 10g / L, magnesium sulfate 2.1g / L, ferrous sulfate 0.1g / L, lactic acid 0.1g / L. According to the formula, various components are weighed and dissolved in water and added into the culture barrel. Sulfate-reducing bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, potassium-solubilizing bacteria, and Bacillus subtilis powder are added into the culture barrel. Closed culture is performed. When the liquid culture medium turns completely black, the culture is completed.

[0052] S5, modification of neutralized slag:

[0053] Weigh the neutralization slag, biochemical remediation materials, water retaining agent, alkalinity regulator and organic fertilizer according to the mass ratio at room temperature, add them into a blender and stir for 5 to 10 minutes to mix the various materials evenly, spread them on the outdoor anti-seepage site and spray them with microbial agents. The spraying frequency is once every three days and the spraying amount is 10L / t of neutralization slag. Naturally cure at room temperature for 15 days, and pack the above-mentioned evenly mixed materials in bags to form a neutralization slag soil product.

[0054] Among them, the mass ratio refers to: 100 parts of neutralized residue, 5-10 parts of biochemical remediation materials, 0.05-0.1 parts of water retaining agent, 0.01-0.03 parts of alkalinity regulator, 5-10 parts of organic fertilizer, and 1.0 part of microbial agent; the microbial agent is a mixture of sulfate-reducing bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, potassium-solubilizing bacteria, and Bacillus subtilis in a mass ratio of 1:1:1:1:1.

[0055] Sulfate-reducing bacteria can use organic matter on the metal surface as a carbon source, and use the hydrogen produced in the bacterial biofilm to reduce sulfate to hydrogen sulfide, which reacts with heavy metal ions to form precipitates, reducing the toxicity and mobility of heavy metal ions and reducing the biological toxicity of the neutralized slag.

[0056] The present invention also provides artificial soil improved by neutralization slag prepared by the above method. The artificial soil improved by neutralization slag comprises the following components by weight: 100 parts of neutralization slag, 5-10 parts of biochemical repair materials, 0.05-0.1 parts of water retaining agent, 0.01-0.03 parts of alkalinity regulator, 5-10 parts of organic fertilizer, and 1.0 part of microbial agent; the microbial agent is a mixture of sulfate reducing bacteria, nitrogen fixing bacteria, phosphate solubilizing bacteria, potassium solubilizing bacteria, and Bacillus subtilis in a mass ratio of 1:1:1:1:1.

[0057] Among them, the mass of particles with a particle size greater than 0.075mm in the neutralized slag does not exceed 50% of the total mass; the mass fraction of calcium sulfate in the neutralized slag is 70-75%, the mass fraction of trace elements is 0.4-0.6%, and the moisture content is less than or equal to 20%; the trace elements are one or more of lead, zinc, arsenic, cadmium, and mercury.

[0058] The neutralized slag meets the requirements of Class I general industrial solid waste.

[0059] Biochemical repair materials are the products of agricultural waste after powdering, puffing and composting. They are dark brown in appearance, with a particle size of ≤1mm, a pH of 6.5-7.0, and a specific gravity of 0.6-0.7g / cm 3 ; On a dry basis, the organic matter content is ≥45%, the nutrient content (N, P, K) is ≥3%, and the humic acid content is ≥20%.

[0060] The agricultural waste is one or more of corn stalks, rice husks, and sugarcane bagasse.

[0061] The biochemical repair material has a loose texture, large porosity, and low specific gravity, and has strong alkalinity regulation and nutrient improvement effects.

[0062] At the same time, the organic binder produced by the decomposition of humic acid in the biochemical remediation material has moderate adhesiveness, which can make the neutralized slag particles stick together, further promote the agglomeration between the neutralized slag particles and the formation of large-size aggregates, effectively increase the content of water-stable aggregates in the neutralized slag, and have a certain fixation effect on water and nutrients.

[0063] The water retaining agent comprises 88%-90% potassium polyacrylate, 8%-10% water and 0.5%-1.0% cross-linking agent.

[0064] Water-retaining agents are beneficial to soil breathability, have good reversibility in water absorption and release, can improve soil structure, and at the same time can promote the development of soil microorganisms and improve the turnover efficiency of soil organic matter.

[0065] The alkalinity regulator is potassium humate. The molecular formula is C3H5OS2K, the solution is slightly acidic, and the pH value is usually between 4.0-6.0. It can adjust the neutralization slag alkalinity, improve the soil aggregate structure, loosen the soil, increase the soil's water and fertilizer retention capacity, reduce the content of heavy metals in the soil, fix nitrogen, dissolve phosphorus, and activate potassium.

[0066] The invention adopts neutralization slag, biochemical repair material, water retaining agent, alkalinity regulator, organic fertilizer and microbial agent to improve the physical, chemical and soil biological properties of neutralization slag, so as to obtain an artificial soil based on neutralization slag modification for plant growth. The artificial soil is prepared by the following components in mass ratio: 100 parts of neutralization slag, 5-10 parts of biochemical repair material, 0.05-0.1 parts of water retaining agent, 0.01-0.03 parts of alkalinity regulator, 5-10 parts of organic fertilizer and 1.0 parts of microbial agent.

[0067] The entire neutralization slag modification process is a process of physical and chemical property improvement and synergistic action of functional microorganisms. Biochemical remediation materials, water retaining agents, alkalinity regulators, and organic fertilizers preliminarily improve the physical and chemical properties of tailings, such as pH, nutrients, and aggregate structure. On this basis, functional microorganisms are applied to form aggregate structures and fix heavy metals to form a primary soil matrix. Microorganisms obtain the nutrients and energy required for growth, and humus is formed after microbial decomposition to promote plant absorption. At the same time, heavy metals are fixed in the tailings to reduce the toxic effects of effective heavy metals on plants.

[0068] During the ecological restoration and greening construction, the above materials are spread on the site to be restored, and clean water is sprayed according to the mass ratio. The water is ordinary domestic water. The amount of water used ensures that the moisture content of the artificial soil reaches 40% to 60%. Plant seeds are sown on the above artificial soil, and watered regularly to ensure the healthy growth of the plants.

[0069] The plant species here are one of ryegrass, tall fescue, alfalfa, lycopersicon esculentum, and bermudagrass, or a mixture of different proportions. Ryegrass is cold-resistant and drought-resistant, with a wide pH range (4-8), and grows well in high-altitude areas; tall fescue is highly resistant to stress, cold, barrenness, and disease; alfalfa has a strong root system and nitrogen-fixing ability, and is an important plant for improving soil; lycopersicon esculentum has the growth characteristics of drought resistance, cold resistance, alkali resistance, and wind and sand resistance; bermudagrass has a well-developed root system, a large number of roots, is extremely heat-resistant and drought-resistant, and is resistant to trampling. It is a good soil and water conservation plant and grows faster on slightly saline-alkali land.

[0070] The preparation method of the artificial soil improved by neutralization slag provided by the present invention is described below in conjunction with specific examples. Unless otherwise specified, the raw materials and reagents in the examples of the present application are purchased through commercial channels.

[0071] Example 1

[0072] This embodiment provides a method for preparing artificial soil based on neutralization slag improvement, and the neutralization slag produced by the neutralization treatment of acidic water lime in a copper mine in the northwest region is taken, and its main chemical components are shown in Table 1, and its particle composition is shown in Table 2. The materials in the proportion shown in Table 3 are added to improve the physical, chemical, and soil biological properties of the neutralization slag to form an artificial soil with physical and chemical properties and nutrients required for plant growth. The physical and chemical parameter results of the finished artificial soil are shown in Table 4.

[0073] The density, porosity, pH value and nutrient content (organic matter, nitrogen, phosphorus and potassium) of the artificial soil made by improving the neutralization slag can meet the relevant requirements of "Greening Planting Soil" (CJ / T 340-2016).

[0074] Table 1 Main chemical components of neutralized slag before modification

[0075] chemical composition Ca S Al Fe Si Cu Zn As content(%) 40.67 28.53 14.81 5.79 3.51 2.43 0.13 0.01

[0076] Table 2 Particle composition of neutralized slag before modification

[0077]

[0078] Table 3 Proportions of components of artificial soil based on neutralized slag modification

[0079]

[0080] Table 4 Physical and chemical properties test data of artificial soil finished products

[0081]

[0082] It can be seen from Table 4 that the density of the neutralized slag before improvement is 1.40g / m 3 , is in a "compact" state, and the density of the improved artificial soil is reduced to 1.19-1.25g / m 3 , which is in the "suitable" state. The porosity has been greatly improved compared with before improvement, and the soil structure, air permeability and water permeability have been improved. The pH value of the artificial soil after improvement has dropped from alkaline to neutral, and the content of nutrients such as organic matter has been greatly improved compared with before improvement, which is more suitable for vegetation growth.

[0083] Artificial soil was prepared according to the material composition ratio in Table 3, and the prepared artificial soil was placed in a planting pot to plant three plants: ryegrass, tall fescue, and alfalfa. At the same time, the neutralized residue before improvement was taken and seeds of the same variety were sown as a comparison. After sowing, the plants were watered and maintained to germinate, and the germination rate and plant growth of the plants were observed. The planting test results are shown in Figure 2. Figure 1 shown.

[0084] It can be seen that the growth condition of ryegrass in the improved artificial soil is good, and the plant height, leaf width, chlorophyll content, etc. are better than those planted with unimproved neutralization residue.

[0085] Example 2

[0086] The neutralized slag produced by the neutralization treatment of acidic water lime in a copper mine in the northwest region was taken and artificial soil was made according to the material composition ratio in Table 3. The prepared artificial soil was placed in a planting pot and three plants, ryegrass, tall fescue and alfalfa, were planted. At the same time, local natural soil was taken and seeds of the same variety were sown as a comparison. After sowing, the plants were watered and maintained to germinate, and the germination rate and plant growth of the plants were observed. The results of the planting test are shown in Tables 5 to 7 and Figure 2 shown.

[0087] The natural soil was collected from the grassland around a copper mining area in the northwest. It is black-gray in color, with the characteristics of shallow soil layer, low humification degree, poor nutrients, and strong coarse bone.

[0088] Table 5 Plant germination rate on artificial soil

[0089] serial number Ryegrass Tall Fescue Alfalfa 1# Artificial soil 88％ 85％ 70％ 2# Artificial soil 90％ 92％ 74％ 3# Artificial soil 92％ 95％ 76％ Natural soil 85％ 80％ 70％

[0090] Table 6 Average plant height of plants on artificial soil

[0091] serial number Ryegrass Tall Fescue Alfalfa 1# Artificial soil 31cm 21cm 14cm 2# Artificial soil 38cm 24cm 17cm 3# Artificial soil 45cm 26cm 19cm Natural soil 22cm 18cm 9cm

[0092] Table 7 Chlorophyll content of plant leaves on artificial soil

[0093] serial number Ryegrass Tall Fescue Alfalfa 1# Artificial soil 33.40SPAD 18.11 SPAD 26.51 SPAD 2# Artificial soil 36.45SPAD 28.07SPAD 39.16SPAD 3# Artificial soil 48.75SPAD 28.90SPAD 40.56 SPAD Natural soil 29.75 SPAD 11.05 SPAD 25.09 SPAD

[0094] It can be seen that compared with natural soil, the germination rate and growth of plants planted in the artificial soil improved by neutralization residue provided by the present invention are improved. Taking the growth of ryegrass as an example, the germination rate of ryegrass in the improved artificial soil can be increased by 3% to 7% compared with natural soil, the plant height is increased by 40.9% to 104.5%, and the chlorophyll content is increased by 12.4% to 65.5%. Compared with unimproved neutralization residue, the germination rate and plant growth of plants planted in the artificial soil improved by neutralization residue provided by the present invention are significantly improved.

[0095] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing artificial soil based on neutralized slag improvement, characterized in that: The steps include: S1, screening of neutralization residue: using a vibrating screen to classify the solid particles of the sludge underflow generated by the acid water neutralization treatment, and separating the fine particles into neutralization residue powder with a particle size greater than 0.075 mm, a mass not exceeding 50% of the total mass, a moisture content not exceeding 20%, and a plasticity index not exceeding 10 for standby use; S2, preparation of biochemical repair materials: Powder: The agricultural waste is initially crushed into a powder with a particle size of ≤200mm and the moisture content is controlled between 40% and 60%; Puffing: Add the powdered agricultural waste into the puffing machine, the puffing temperature is between 100℃ and 150℃, the puffing pressure is between 1.0MPa and 1.5MPa, the puffing time is between 0.25h and 2h, and the filaments with a length of about 50-100mm and a width of 1-2mm are formed; Composting: Make an arched pile with a length of 1.5m to 3m and a width of 0.75m to 1.5m. Cover the top of the arched pile with film, keep the temperature between 40℃ and 60℃, ferment for 15 to 30 days, spray water regularly to keep the moisture content between 60% and 70%, and turn the pile every 5 to 10 days; The fermentation product is air-dried in a cool and ventilated place, and the moisture content after air-drying is 5% to 15%, and crushed into powder with a particle size of ≤1mm; S3, preparation of organic fertilizer: mixing air-dried cow dung and sheep dung in a mass ratio of 1:1 and crushing them, adding actinomycetes and Trichoderma, fermenting and composting to form organic fertilizer for standby use; S4, microbial agent preparation process: Preparation of culture medium: glucose 0.9g / L, ammonium chloride 1.0g / L, sodium chloride 10g / L, magnesium sulfate 2.1g / L, ferrous sulfate 0.1g / L, lactic acid 0.1g / L. According to the formula, various components are weighed and dissolved in water and added into the culture barrel. Sulfate-reducing bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, potassium-solubilizing bacteria, and Bacillus subtilis powder are added into the culture barrel. Closed culture is performed. When the liquid culture medium turns completely black, the culture is completed. S5, modification of neutralized slag: Weigh the neutralization slag, biochemical remediation materials, water retaining agent, alkalinity regulator and organic fertilizer according to the mass ratio at room temperature, add them into a blender and stir for 5 to 10 minutes to mix the various materials evenly, spread them on the outdoor anti-seepage site and spray them with microbial agents. The spraying frequency is once every three days and the spraying amount is 10L / t of neutralization slag. Naturally cure at room temperature for 15 days, and pack the above-mentioned evenly mixed materials in bags to form a neutralization slag soil product.

2. The method for preparing artificial soil based on neutralized slag improvement according to claim 1, characterized in that: In step S5, the mass ratio refers to: 100 parts of neutralized slag, 5-10 parts of biochemical remediation materials, 0.05-0.1 parts of water retaining agent, 0.01-0.03 parts of alkalinity regulator, 5-10 parts of organic fertilizer, and 1.0 part of microbial agent; the microbial agent is a mixture of sulfate-reducing bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, potassium-solubilizing bacteria, and Bacillus subtilis in a mass ratio of 1:1:1:1:

1.

3. An artificial soil improved by neutralization slag, prepared according to the preparation method according to any one of claims 1 to 2, characterized in that: The artificial soil improved by neutralization residue comprises the following components in parts by weight: 100 parts of neutralization residue, 5-10 parts of biochemical remediation materials, 0.05-0.1 parts of water retaining agent, 0.01-0.03 parts of alkalinity regulator, 5-10 parts of organic fertilizer, and 1.0 parts of microbial agent; the microbial agent is a mixture of sulfate reducing bacteria, nitrogen fixing bacteria, phosphate solubilizing bacteria, potassium solubilizing bacteria, and Bacillus subtilis in a mass ratio of 1:1:1:1:

1.

4. The artificial soil improved by neutralized slag according to claim 3, characterized in that: The mass of particles with a particle size greater than 0.075 mm in the neutralized slag does not exceed 50% of the total mass; the mass fraction of calcium sulfate in the neutralized slag is 70-75%, the mass fraction of trace elements is 0.4-0.6%, and the moisture content is less than or equal to 20%; the trace elements are one or more of lead, zinc, arsenic, cadmium, and mercury.

5. The artificial soil improved by neutralized slag according to claim 4, characterized in that: The neutralized slag meets the requirements of Class I general industrial solid waste.

6. The artificial soil improved by neutralized slag according to claim 3, characterized in that: The biochemical repair material is a product of agricultural waste after powdering, puffing and composting, with a dark brown appearance, a particle size of ≤1 mm, a pH of 6.5-7.0, and a specific gravity of 0.6-0.7 g / cm 3 ; On a dry basis, the organic matter content is ≥45%, the nutrient content is ≥3%, and the humic acid content is ≥20%; the agricultural waste is one or more of corn stalks, rice husks, and sugarcane bagasse.

7. The artificial soil improved by neutralized slag according to claim 3, characterized in that: The water retaining agent comprises 88%-90% potassium polyacrylate, 8%-10% water and 0.5%-1.0% cross-linking agent.

8. The artificial soil improved by neutralized slag according to claim 3, characterized in that: The alkalinity regulator is potassium humate.

9. The artificial soil improved by neutralized slag according to claim 3, characterized in that: The organic fertilizer is a fermented and decomposed mixture of cow dung and sheep dung in a mass ratio of 1:1.

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