Ecological soil prepared by using washed quartz sand mine tailings and method thereof

Abstract

The present application relates to the technical field of quartz sand washing tailing mud resource utilization, and particularly relates to an ecological soil prepared from quartz sand washing tailing mud and a preparation method thereof, which uses quartz sand washing tailing mud as a main raw material, and is supplemented with coal gangue, biological substrate and composite microbial bacteria to prepare the ecological soil, the leaching rate of heavy metals of the ecological soil is low, the stabilization and solidification effect is good, secondary pollution of the environment caused by heavy metals can be avoided, the soil properties of the ecological soil can be improved, the quality of the ecological soil can be improved, the resource utilization amount of the quartz sand washing tailing mud can be increased, the consumption amount can be increased, and the treatment cost and difficulty of the quartz sand washing tailing mud can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource utilization of washed quartz sand tailings, and particularly relates to an ecological soil prepared from washed quartz sand tailings and a preparation method thereof. BACKGROUND

[0002] Quartz sand needs to be washed and beneficiated before being used as a glass sand raw material, so that the purity of the quartz sand reaches more than 99% of the concentrate. A large amount of tailings is produced during the washing and beneficiation of quartz sand. Washed quartz sand tailings are usually used for the production of building materials, but as the market demand for building materials decreases, the output of washed quartz sand tailings is much greater than the consumption, resulting in the stockpiling of washed quartz sand tailings.

[0003] The main components of washed quartz sand tailings are SiO2, Al2O3, etc., and the content of harmful components is relatively low; however, the soil properties such as bulk density, water retention, air permeability, electrical conductivity, nutrients, trace element content, microbial content, organic matter content, and fertility are poor, and moreover, the washed quartz sand tailings appear light yellow after pressure filtration, the tailings particle size is less than 325 mesh (0.045 mm), which belongs to silt, and is easy to harden, resulting in not only a large amount of land resources being occupied when the washed quartz sand tailings are stockpiled, but also secondary pollution to the environment.

[0004] Therefore, seeking a suitable large-scale disposal approach for washed quartz sand tailings has become a key technology for the sustainable development of the washed quartz sand tailings industry, and is a technical problem that the current washed quartz sand tailings industry urgently needs to solve.

[0005] At present, tailings have been widely studied in the field of artificial soil preparation and certain technologies have been formed, for example: patent application No. CN202410192075.8 discloses that after sea mud sand is desalinated and sorted to obtain sea sand, the remaining tailings are pressure-filtered and dewatered to obtain desalination tailings; the desalination tailings are crushed and conditioned to obtain tailings crushed material; dry pig manure is pyrolyzed and cooled in turn to obtain pig manure biochar; the tailings crushed material and the pig manure biochar are mixed at one time to obtain a biochar mixture; the garden greening planting soil and the biochar mixture are mixed at two times to obtain conditioned planting soil; the conditioned planting soil is cured to obtain carpet grass planting soil; the microbial community is activated, the soil structure is improved, the activity of microorganisms is enhanced, the microbial community structure is enriched, and the microbial diversity is improved, so as to meet the normal growth of carpet grass and realize the resource utilization of desalination tailings.

[0006] For example, patent application No. CN202411507530.5 discloses that the mine tailings are pretreated by screening to obtain mine tailings powder; oyster shell is ground and pretreated by screening to obtain oyster shell powder; the pretreated mine tailings powder and oyster shell powder are mixed, stirred and dried to obtain material powder; and the biochar prepared from different types of crop straw is mixed with the material powder to prepare a soil conditioner. The harmless mine tailings and biochar can improve soil structure and adjust soil texture, and the addition of oyster shell powder can also improve soil fertility, provide rich nutrients for crop production, promote crop growth, increase yield, and have the functions of improving fertilizer utilization rate and soil improvement.

[0007] However, there is no technical content in the prior art on how to use washed quartz sand mine tailings to prepare soil while meeting the requirements of soil properties and reducing the leachable rate of heavy metals (solidification effect), resulting in a lack of technology for using washed quartz sand mine tailings to produce artificial soil. SUMMARY

[0008] Based on the above technical problems, the present application provides an ecological soil prepared from washed quartz sand mine tailings and a method thereof.

[0009] The specific technical solution is as follows:

[0010] One of the purposes of the present application is to provide a method for preparing an ecological soil from washed quartz sand mine tailings, comprising the following steps:

[0011] (1) drying the washed quartz sand mine tailings naturally to a moisture content of ≤30%, crushing to 4-10 mesh to obtain tailings particles; crushing coal gangue to 4-10 mesh to obtain coal gangue particles;

[0012] (2) uniformly mixing the coal gangue particles with the biological substrate and the compound microbial agent at a mass ratio of 1:0.1-0.5:0.001-0.010, and aging at normal temperature and pressure for 1-3 days to obtain a compound material;

[0013] (3) uniformly mixing the tailings particles with the compound material at a mass ratio of 1-5:1 based on the mass of the coal gangue particles, and aging at normal temperature and pressure for 1-3 days to obtain the ecological soil.

[0014] The washed quartz sand mine tailings are used as the main raw material, supplemented by coal gangue, biological substrate and compound microbial agent to prepare the ecological soil. The ecological soil has a low leachable rate of heavy metals, a good solidification effect, can avoid secondary pollution of heavy metals to the environment, can improve the soil properties of the ecological soil, can improve the quality of the ecological soil, can increase the amount of resource utilization of the washed quartz sand mine tailings, can increase the amount of absorption, and can reduce the cost and difficulty of processing the washed quartz sand mine tailings.

[0015] Preferably, the biological matrix is one or a mixture of any mass ratio of biological organic fertilizer, humic acid, straw, dry branches, dry leaves, vinasse, humus soil. For example, the straw can be corn straw, wheat straw, etc. For example, the humus soil is humus soil formed by the decay of fallen leaves in the forest.

[0016] In order to improve the effect of heavy metal stabilization and solidification of ecological soil, reduce the leaching rate of heavy metal, improve the soil properties of ecological soil, and improve the quality of ecological soil, preferably, the composite microbial bacteria are mixed in equal mass ratio by promoting and soil improvement type microbial bacteria, biocontrol type microbial bacteria, and other microbial bacteria; wherein the other microbial bacteria are sulfur-oxidizing bacteria, Bacillus laterosporus, and Aspergillus niger mixed in equal mass ratio; the promoting and soil improvement type microbial bacteria are one of Bacillus megaterium, Bacillus mucilaginosus, and Bacillus mycoides; and the biocontrol type microbial bacteria are one of Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus polymyxa.

[0017] More preferably, the composite microbial bacteria are mixed in equal mass ratio by Bacillus megaterium, Bacillus subtilis, and other microbial bacteria; and the other microbial bacteria are mixed in equal mass ratio by sulfur-oxidizing bacteria, Bacillus laterosporus, and Aspergillus niger.

[0018] Preferably, in the step (2), the coal gangue particles are mixed with the biological matrix and the composite microbial bacteria in a mass ratio of 1:0.2:0.003; and in the step (3), the tailing particles are mixed with the composite material in a mass ratio of 2:1.

[0019] Preferably, the washed quartz sand mine tailing soil indexes are that the organic matter content is 0, the salt content is 0.21 mS / cm, the bulk density is 0.61 g / m 3 , the infiltration rate is 0 mm / h, the porosity is 8.45%, the aeration degree is 1.089%, and the pH is 7.78.

[0020] Preferably, the main component mass percentage content of the washed quartz sand mine tailing is: SiO285.46%, Al2O311.68%, Fe2O30.77%, Na2O 0.015%, MgO 0.10%, P2O50.069%, SO30.020%, Cl0.0084%, K2O 0.82%, CaO 0.19%, TiO2 0.55%, Cr2O30.012%, MnO 0.013%, NiO0.0059%, CuO 0.0058%, As2O30.0033%, Rb2O 0.0022%, SrO 0.013%, Y2O30.0061%, ZrO20.030%, ThO20.0036%, F - 0.2%.

[0021] Preferably, the coal gangue has the following main component mass percentage: SiO249.23%, Al2O320.11%, Fe2O38.99%, CaO 3.24%, K2O 0.10%, MgO 0.96%.

[0022] The second purpose of the present application is to provide the ecological soil prepared by the above method.

[0023] Compared with the prior art, the technical effects of the present application are embodied in that:

[0024] The present application changes the abandoned quartz sand washing tailings resources and coal gangue resources into treasure, so that the beneficial trace elements for plant growth in the coal gangue can be compounded into the quartz sand washing tailings, the soil properties of the quartz sand washing tailings are improved, the selection of the biological substrate and the compound microbial agent is combined, the nutrient matching in the ecological soil is reasonable, the heavy metal stabilization and solidification effect in the ecological soil is enhanced, the leaching rate of the heavy metal is reduced, the consumption amount of the quartz sand washing tailings is improved, and the treatment cost and difficulty of the quartz sand washing tailings are reduced.

[0025] The process flow of the present application is simple and easy to operate. DETAILED DESCRIPTION

[0026] In order to facilitate the technical personnel in the art to fully understand the technical solutions of the present application, the following description of the drawings provided is made in combination with the technical solution content and the provided drawings.

[0027] Figure 1 The process flow chart of the present application.

[0028] Figure 2 The appearance photograph of the quartz sand washing tailings after being pressed into blocks.

[0029] Figure 3 The ecological soil photo prepared by the present application.

[0030] Figures 4a-4d The sample inspection and detection report prepared by adding the humus soil as the biological substrate in the present application. DETAILED DESCRIPTION

[0031] For the convenience of the person skilled in the art to make a correct understanding of the present invention, so that the person skilled in the art can fully understand the technical content of the present invention, the technical solution of the present invention will be further described below in combination with specific embodiments and drawings, but this description does not limit the scope of protection of the present invention, the protection scope of the present invention cannot be limited to the following description by the person skilled in the art, any person skilled in the art or person familiar with the art, on the basis of the present invention, according to the technical solution and the invention idea of the present invention, the equivalent replacement or change made by them should be covered within the protection scope of the present invention.

[0032] As Figure 1 shown, in some embodiments, the method for preparing ecological soil by using washed quartz sand mine tailings mud comprises the following steps:

[0033] (1) The washed quartz sand mine tailings mud is naturally air-dried to a moisture content of ≤30%, for example: 10%, 15%, 20%, 30%, etc., and is crushed to 4-10 mesh to obtain tailings particles; the coal gangue is crushed to 4-10 mesh to obtain coal gangue particles;

[0034] (2) The coal gangue particles, biological substrate and compound microbial agent are mixed uniformly at a mass ratio of 1:0.1-0.5:0.001-0.010, for example: 1:0.1:0.003, 1:0.2:0.003, 1:0.15:0.003, etc., and are aged at normal temperature and pressure for 1-3 days, for example: 1 day, 2 days, 3 days, etc., to obtain a compound material;

[0035] (3) The tailings particles and the compound material are mixed uniformly at a mass ratio of 1-5:1, for example: 1:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 5:1, etc., based on the mass of the coal gangue particles, and are aged at normal temperature and pressure for 1-3 days, for example: 1 day, 2 days, 3 days, etc., to obtain the ecological soil.

[0036] The tailings with poor soil properties are used as raw materials, and are aged after being mixed with coal gangue, biological substrate and compound microorganisms to realize putrefaction and maturation, so that the nutrients in the coal gangue, biological substrate and compound microorganisms are uniformly mixed, and then the tailings particles are added and mixed uniformly, and aged, and the mixing ratio of each raw material is strictly controlled, so that the soil properties of the obtained ecological soil are improved, and the addition of the compound microorganisms reduces the leachable rate of heavy metals and improves the stable solidification effect of heavy metals in the ecological soil.

[0037] In some embodiments of the present invention, the biological substrate is a mixture of one or more of biological organic fertilizer, humic acid, straw, dry branches, dry leaves, vinasse and humus soil at any mass ratio. It can supplement organic matter and enhance the soil properties of the ecological soil prepared by using tailings as the main raw material.

[0038] In certain embodiments of this invention, the composite microbial strain is composed of growth-promoting and soil-improving microbial strains, biocontrol microbial strains, and other microbial strains mixed in equal mass ratios. The other microbial strains are sulfur-oxidizing bacteria, Bacillus laterosporus, and Aspergillus niger mixed in equal mass ratios. The growth-promoting and soil-improving microbial strains are one of Bacillus mucilaginosus, Bacillus lentigines, and Bacillus megaterium. The biocontrol microbial strains are one of Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus polymyxa. This will help reduce the leaching rate of heavy metals and enhance the stabilization and solidification effect of heavy metals in ecological soils.

[0039] In some embodiments of this invention, the composite microbial strain is composed of Bacillus megaterium, Bacillus subtilis, and other microbial strains mixed in equal mass ratios; the other microbial strains are composed of sulfur-oxidizing bacteria, Bacillus laterosporus, and Aspergillus niger mixed in equal mass ratios. This enhances the curing effect on heavy metals.

[0040] In certain embodiments of this invention, in step (2), coal gangue particles are mixed with biological substrate and composite microbial agent at a mass ratio of 1:0.2:0.003; and in step (3), tailings particles are mixed with composite material at a mass ratio of 2:1. This helps to reduce the salinity of ecological soil.

[0041] In order to better verify the technical effects of this invention, the researchers of this invention conducted the following experimental studies:

[0042] The tailings from the washing of quartz sand mine were analyzed, and their main components and mass percentages were determined. The results were as follows: SiO2 85.46%, Al2O3 11.68%, Fe2O3 0.77%, Na2O 0.015%, MgO 0.10%, P2O5 0.069%, SO3 0.020%, Cl 0.0084%, K2O 0.82%, CaO 0.19%, TiO2 0.55%, Cr2O3 0.012%, MnO 0.013%, NiO 0.0059%, CuO 0.0058%, As2O3 0.0033%, Rb2O 0.0022%, SrO 0.013%, Y2O30.0061%, ZrO20.030%, ThO20.0036%, F -The content of heavy metals in the tailings was 0.2%. This indicates that the main components of the tailings are SiO2, Al2O3, and Fe2O3, with SiO2 content exceeding 85%. The contents of heavy metals such as Cr and As are relatively low, suggesting that heavy metals have a minimal impact on the soil environment. Soil properties, including pH, organic matter, salinity, bulk density, infiltration rate, porosity, and aeration, were measured in the tailings from the washed quartz sand mine. The results are shown in Table 1 below.

[0043] Table 1

[0044]

[0045] It is evident that the tailings from the washing of quartz sand mines tend to be neutral, and the organic matter content, soil infiltration rate, and other indicators do not meet the requirements of standards such as the "Quality Control Standard for Land Reclamation" (TD / T1036-2013) and "Green Planting Soil" (CJ / T 340-2016). Therefore, the tailings from the washing of quartz sand mines cannot be used directly as soil and need to be modified.

[0046] Coal gangue is an industrial byproduct produced during coal mining. Testing shows its main components by mass percentage are: SiO2 49.23%, Al2O3 20.11%, Fe2O3 8.99%, CaO 3.24%, K2O 0.10%, and MgO 0.96%. In addition, it contains trace elements such as B, Mn, Cu, and Co. Therefore, coal gangue can replenish the soil with trace elements and improve its composition.

[0047] In view of the above, this study uses coal gangue and quartz sand mine tailings as the main raw materials to prepare ecological soil, in order to broaden the scope of resource utilization of quartz sand mine tailings, increase the amount of quartz sand mine tailings disposed of, reduce the amount of stockpiled tailings, and reduce environmental pollution.

[0048] Experiment 1: Study on soil properties of mixtures formed by coal gangue particles and tailings particles.

[0049] The tailings from the washed quartz sand mine were naturally air-dried to a moisture content of 30%, then pulverized to a mesh size of 4-10 to obtain tailings particles. Coal gangue particles were also pulverized to a mesh size of 4-10 to obtain coal gangue particles. The tailings particles and coal gangue particles were mixed according to the mass ratios shown in Table 2 below to form a mixture. The soil properties of the mixture were tested according to CJ / T 340-2016, and the results are shown in Table 2 below.

[0050] Table 2

[0051]

[0052] Table 2 shows that different mass ratios of tailings particles to coal gangue particles will lead to changes in the soil properties of the mixture formed by the mixture of tailings particles and coal gangue particles. Overall, the higher the mass ratio of tailings particles to coal gangue particles, the worse the soil properties. However, as the amount of tailings particles increases, the salt content in the resulting mixture gradually decreases. Therefore, the mass ratio of tailings particles to coal gangue particles should be properly controlled to ensure that the resulting mixture has better soil property indicators when used as ecological soil.

[0053] Experiment 2: Study on the impact of different raw material mass ratios on soil properties of ecological soil.

[0054] Tailings particles, coal gangue particles, and biological substrate (corn stalks crushed through a 10-mesh sieve) were used according to the mass ratios shown in Table 3 below. First, the coal gangue particles and biological substrate were mixed and aged at room temperature and pressure for 3 days to obtain a composite material. Then, the composite material was mixed evenly with the tailings particles and aged at room temperature and pressure for another 3 days to obtain ecological soil. Soil property indicators of the obtained ecological soil were tested, and the results are shown in Table 3 below.

[0055] Table 3

[0056]

[0057] Table 3 shows that the soil properties of the resulting ecological soil improved with the increase of the amount of biological substrate. While keeping the amount of biological substrate constant, the overall soil property indicators of the ecological soil deteriorated as the mass ratio of tailings particles to coal gangue particles increased, and the salt content also showed a significant downward trend. However, in order to improve the soil properties of tailings, the amount of coal gangue cannot be too low. Therefore, the mass ratio of tailings particles to coal gangue particles should be properly controlled to ensure that the resulting mixture has better soil property indicators when used as ecological soil, and to ensure that the amount of tailings from the quartz sand mine is large enough to be disposed of.

[0058] Experiment 3: Study on the effects of compound microbial addition on soil properties of ecological soil.

[0059] Based on Experiment 2, a sample was taken from the experimental group with a ratio of tailings particles: coal gangue particles: biological matrix of 100:50:5. Heavy metal analysis was performed according to CJ / T 340-2016 "Green Planting Soil". The results are shown in Table 4 below:

[0060] Table 4 (Unit: mg / kg)

[0061]

[0062] Based on this, compound microbial agents A, B, and C were prepared respectively. Compound microbial agent A consisted of *Bacillus megaterium* as a growth-promoting and soil-improving microorganism, *Bacillus subtilis* as a biocontrol microorganism, and other microorganisms mixed in equal mass ratios. The other microorganisms were sulfur-oxidizing bacteria, *Bacillus laterosporus*, and *Aspergillus niger* mixed in equal mass ratios. Compound microbial agent B consisted of *Bacillus mucilaginosus* as a growth-promoting and soil-improving microorganism, *Bacillus polymyxa* as a biocontrol microorganism, and other microorganisms mixed in equal mass ratios, otherwise the same as compound microbial agent A. Compound microbial agent C consisted of *Bacillus mucilaginosus* as a growth-promoting and soil-improving microorganism, *Bacillus amyloliquefaciens* as a biocontrol microorganism, and other microorganisms mixed in equal mass ratios, otherwise the same as compound microbial agent A.

[0063] Compound microbial agents A, B, and C were prepared according to a mass ratio of tailings particles: coal gangue particles: biological substrate: compound microbial agent of 100:50:5:0.15. First, the coal gangue particles were mixed with the biological substrate and compound microbial agents, and then piled and aged at room temperature and pressure for 3 days to obtain a composite material. Next, the composite material was mixed evenly with the tailings particles and piled and aged at room temperature and pressure for 3 days to obtain ecological soil. The heavy metal content of the obtained ecological soil was tested, and the results are shown in Table 5. Simultaneously, the soil properties of the obtained ecological soil were tested, and the results are shown in Table 6.

[0064] Table 5 (Unit: mg / kg)

[0065]

[0066] Table 6

[0067]

[0068] Tables 3, 4, 5, and 6 show that adding compound microbial agents helps to enhance the stabilization and solidification of heavy metals, reduce the leaching rate of heavy metals, and improve the soil properties and quality of ecological soil. Different types of compound microbial agents will have different effects on the quality of ecological soil. In this invention, compound microbial agent A is preferred.

[0069] Experiment 4: Sample preparation and testing.

[0070] Following the sample preparation method in Experiment 3, the samples were prepared according to a mass ratio of tailings particles: coal gangue particles: biological matrix (humus): compound microbial agent B of 100:40:5:0.30. The test results are as follows: Figures 4a-4dAs shown in the figure, the test results indicate that the present invention utilizes humus as a biological substrate and adds compound microbial agent B to prepare ecological soil. This ecological soil has superior soil properties and excellent quality. Moreover, the detectable content of heavy metals is low, which can reduce the migration rate of heavy metals.

[0071] For any other matters not covered in this invention, they can be implemented by referring to existing technology or common knowledge known to those skilled in the art, using conventional technical means, such as: the method of mixing compound microbial agents, the operation method of aging treatment in a normal temperature and pressure environment, etc.

Claims

1. A method for preparing ecological soil using tailings from washed quartz sand mines, characterized in that, Includes the following steps: (1) Air-dry the tailings of the washed quartz sand mine to a moisture content of ≤30%, and crush them to 4-10 mesh to obtain tailings particles; crush the coal gangue to 4-10 mesh to obtain coal gangue particles. (2) Mix coal gangue particles with biological matrix and composite microbial agent in a mass ratio of 1:0.1-0.5:0.001-0.010, and age them at room temperature and pressure for 1-3 days to obtain composite material; (3) The composite material is made by mixing tailings particles and composite material at a mass ratio of 1-5:1 based on the mass of coal gangue particles, and aging it at room temperature and pressure for 1-3 days. The compound microbial agent is composed of growth-promoting and soil-improving microorganisms, biocontrol microorganisms, and other microorganisms mixed in equal mass ratios; wherein, the other microorganisms are sulfur-oxidizing bacteria, Bacillus laterosporus, and Aspergillus niger mixed in equal mass ratios; the growth-promoting and soil-improving microorganisms are one of Bacillus megaterium, Bacillus mucilaginosus, and Bacillus lentigines; and the biocontrol microorganisms are one of Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus polymyxa. The soil indicators of the tailings from the quartz sand mine are: organic matter content of 0, salt content of 0.21 mS / cm, bulk density of 0.61 g / m³, infiltration rate of 0 mm / h, porosity of 8.45%, air permeability of 1.089%, and pH of 7.

78. The main components of the coal gangue, by mass percentage, are: SiO2 49.23%, Al2O3 20.11%, Fe2O3 8.99%, CaO 3.24%, K2O 0.10%, and MgO 0.96%.

2. The method as described in claim 1, characterized in that, The bio-matrix is ​​a mixture of one or more of the following in any mass ratio: bio-organic fertilizer, humic acid, straw, dead branches, dead leaves, distiller's grains, and humus.

3. The method as described in claim 1, characterized in that, The compound microbial agent is composed of Bacillus megaterium, Bacillus subtilis and other microorganisms mixed in equal mass ratios; the other microorganisms are sulfur-oxidizing bacteria, Bacillus laterosporus and Aspergillus niger mixed in equal mass ratios.

4. The method as described in claim 1, characterized in that, In step (2), coal gangue particles are mixed with biological matrix and composite microbial agent at a mass ratio of 1:0.2:0.003; and in step (3), tailings particles are mixed with composite material at a mass ratio of 2:

1.

5. The method as described in claim 1, characterized in that, The main components of the tailings from the quartz sand mine, by mass percentage, are as follows: SiO2 85.46%, Al2O3 11.68%, Fe2O3 0.77%, Na2O 0.015%, MgO 0.10%, P2O5 0.069%, SO3 0.020%, Cl 0.0084%, K2O 0.82%, CaO 0.19%, TiO2 0.55%, Cr2O3 0.012%, MnO 0.013%, NiO 0.0059%, CuO 0.0058%, As2O3 0.0033%, Rb2O 0.0022%, SrO 0.013%, Y2O3 0.0061%, ZrO2 0.030%, ThO2 0.0036%, F - 0.2%.

6. An ecological soil prepared by the method according to any one of claims 1-5.

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