A modified artificial soil based on tailings and a preparation method thereof

Abstract

The application discloses a preparation method of modified tailing-based artificial soil, which comprises the following steps: cleaning and soaking tailings with a weak alkali solution to obtain pretreated tailings; dehydrating sludge and grinding the sludge to a suitable particle size to obtain pretreated sludge; mixing the pretreated tailings and the pretreated sludge to obtain modified tailings; subjecting sawdust to biological drying and composting treatment by using specific microbial agents with high-temperature resistance and decomposition capacity under a specific period to obtain fermented sawdust; and mixing the modified tailings and the fermented sawdust at a certain ratio, adding a proper amount of water, placing the mixture in a natural environment, controlling temperature, humidity and light conditions, and performing a certain period of natural balancing process to obtain the tailing-based artificial soil. The artificial soil has good structural stability and can realize plant reclamation and ecological restoration of tailings.

Description

Artificial soil based on tailings modification and its preparation method Technical Field

[0001] This invention relates to the field of tailings recycling and treatment technology, specifically to an artificial soil based on tailings modification and its preparation method. Background Technology

[0002] Tailings stockpiles typically occupy significant amounts of land and often contain harmful substances such as heavy metals, chlorides, cyanides, and organic reagents. Furthermore, the particle size of tailings is close to fine sand, making it impossible to form a compact stockpile. Therefore, traditional stockpiling methods cannot achieve the harmless treatment, volume reduction, and resource utilization of tailings. Currently, the main methods for utilizing tailings include: filling underground mining areas, re-selecting valuable elements, preparing building materials, and soil reclamation. Among these, soil reclamation, as a green and long-term treatment method, has become an effective way to manage tailings, reduce ecological risks, and provide ecological stability.

[0003] The core objective of tailings-modified artificial soil is to establish an ecosystem with mineral biological functions to accelerate the accumulation of organic matter and microbial diversity. This method aims not only to immobilize pollutants by forming functional soil but also to establish a stable and resilient ecosystem within the tailings. Numerous studies have demonstrated that adding soil conditioners to tailings can promote the tailings-to-soil process, thereby accelerating the reclamation of mining areas. However, traditional tailings modification methods typically employ physical and chemical treatments, such as adding admixtures, solidifying agents, or altering the physical structure. These methods merely change the properties of the tailings and fail to achieve a comprehensive structural transformation. The tight packing and lack of porosity between tailings particles limit soil permeability, aeration, and root growth space. Furthermore, tailings-modified artificial soil exhibits low stability in terms of soil fertility, water conservation, and ecological function. Soils improved using traditional methods often suffer from rapid nutrient loss, poor water retention, and susceptibility to soil collapse. These issues limit the long-term stability and sustainability of tailings-modified artificial soil. Summary of the Invention

[0004] In view of the above-mentioned shortcomings, this invention provides an artificial soil based on tailings modification and its preparation method. This invention utilizes a comprehensive treatment technology, including compound microbial agents, bio-fermented sawdust, and wastewater treatment sludge, combined with a biological balance process, to achieve comprehensive improvement and resource recycling of tailings. By optimizing the tailings modification process and process parameters, tailings are mixed with other raw materials to form a stable artificial soil with a good structure. Simultaneously, through the selection of suitable plant types and the control of plant planting parameters, vegetative reclamation and ecological restoration of the tailings are achieved.

[0005] To achieve the above objectives, the present invention provides a method for preparing artificial soil based on tailings modification, comprising the following steps:

[0006] Step 1: Wash and soak the tailings with a weak alkaline solution to obtain pretreated tailings; dewater the sludge and grind it to a suitable particle size using a grinding device to obtain pretreated sludge; mix the pretreated tailings and pretreated sludge in a certain proportion to obtain modified tailings.

[0007] Step 2: Under a specific cycle, the sawdust is biologically dried and decomposed using a specific microbial agent with high temperature resistance and decomposition ability to obtain biologically fermented sawdust.

[0008] Step 3: Using modified tailings and bio-fermented wood chips as raw materials, mix them in a certain proportion and add an appropriate amount of water. Place them in a natural environment, control the temperature, humidity and light conditions, and carry out a natural balancing process for a certain period of time to obtain artificial soil based on tailings modification.

[0009] According to one aspect of the present invention, in step 1, the weak alkaline solution is a 0.5% sodium hydroxide solution, and the mass ratio of the tailings to the sodium hydroxide solution is 10:1.

[0010] According to one aspect of the present invention, in step 1, the temperature of the dehydration treatment is 65°C and the time is 2 hours; the diameter of the suitable particle size is 0.2-0.3 mm.

[0011] According to one aspect of the present invention, in step 1, the mass ratio of the pretreated tailings to the pretreated sludge is 9:1; the mixing time of the pretreated tailings and the pretreated sludge is 40 min, and the temperature is 80°C.

[0012] According to one aspect of the present invention, in step 2, the specific microbial agent having heat resistance and decomposition ability is a mixed bacteria, the mixed bacteria including Aspergillus, thermophilic aerobic bacteria, Bacillus, and Fibriocarpus.

[0013] According to one aspect of the present invention, in step 2, the temperature of the biological drying and composting treatment is 80°C; the culture medium for the biological drying and composting treatment is CYS culture medium; the parameters for the biological drying and composting treatment are: rotating forward for 10 minutes, stopping for 20 minutes, rotating backward for 10 minutes, stopping for 20 minutes, and repeating the cycle; the ventilation rate is set to 0.2 L / (kg·min); and the fermentation cycle is set to 14 days.

[0014] According to one aspect of the invention, in step 3, the ratio of the modified tailings to the bio-fermented wood chips is 10:1.

[0015] According to one aspect of the present invention, in step 3, the temperature, humidity and light conditions are as follows: temperature: 21℃-12h and 25℃-12h cycle; humidity: tap water is added every 5 days to maintain a moisture content of 15-20% and humidity is controlled at 75%; light conditions: 0 lux-12h and 8000 lux-12h.

[0016] The beneficial effects of this invention are:

[0017] (1) Comprehensive treatment: This invention adopts comprehensive treatment technology, combining multiple treatment methods such as compound microbial agents, bio-fermented wood chips and wastewater treatment sludge, to comprehensively treat the diverse components and particle size distribution characteristics of tailings, thereby improving the comprehensiveness and integration of the treatment effect;

[0018] (2) Resource recycling and utilization: By improving tailings into artificial soil, the goal of effective utilization of waste and resource recycling is achieved. The useful components in the tailings are transformed and fixed in the artificial soil, giving it the ability to retain nutrients and water required for plant growth. Thus, it can be used in agriculture, horticulture and other fields to improve the sustainable utilization efficiency of land resources.

[0019] (3) Ecological restoration and environmental protection: By transforming tailings into artificial soil with stable ecological functions, ecological restoration and environmental protection of the mining area are achieved. The formation of artificial soil promotes vegetation growth and soil biodiversity, improving the ecological environment of the mining area. At the same time, by fixing and degrading pollutants in tailings, the risk of pollution to water bodies and soil is reduced, improving environmental quality and the health of the ecosystem. Attached Figure Description

[0020] Figure 1 is a schematic diagram of the preparation process of artificial soil based on tailings modification according to the present invention. Detailed Implementation

[0021] To make the present invention easier to understand, specific embodiments are described below to further illustrate the invention. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical terms used below have the same meaning as understood by those skilled in the art; unless otherwise specified, the raw materials and reagents involved herein can be purchased commercially or obtained by known methods.

[0022] To address the problems in the prior art, this invention provides a method for preparing artificial soil based on tailings modification, the process flow of which is shown in Figure 1, and includes the following steps:

[0023] (1) Tailings modification treatment

[0024] a. Tailings Pretreatment: The tailings are washed and soaked in a weakly alkaline solution (sodium hydroxide solution) to reduce organic contaminants on their surface. Washing and soaking the tailings in the weakly alkaline solution promotes the chemical reaction between organic contaminants and hydroxide ions in the solution. Organic contaminants can exist on the surface and inside the tailings in the form of fatty acids, lipids, hydrocarbons, etc. Through washing and prolonged soaking, the hydroxide ions in the weakly alkaline solution can neutralize the organic contaminants, releasing them from the tailings particles. This improves the surface properties of the tailings, reduces the impact of organic contaminants, and provides a better foundation for subsequent improvement processes.

[0025] b. Wastewater treatment sludge pretreatment: The wastewater treatment sludge is dewatered using a dryer and then ground to an appropriate particle size using grinding equipment to improve the efficiency and uniformity of tailings modification. The wastewater treatment sludge is dewatered through heating and dewatering. The grinding equipment uses shearing, crushing, and impact actions to refine and homogenize the sludge particles, breaking down the sludge's aggregate structure and increasing its surface area and accessibility. This improves the effectiveness of subsequent tailings modification processes.

[0026] c. Raw material composition: pretreated tailings and pretreated wastewater treatment sludge.

[0027] d. Pre-treated tailings and pre-treated wastewater treatment sludge are mixed to form a tailings mixture: The amounts of pre-treated tailings and pre-treated wastewater treatment sludge are set and mixed in a certain proportion. The mixture is stirred in a mixing tank with specific stirring time, temperature, and aeration conditions to obtain the modified tailings. The improvement effect of pre-treated sludge on pre-treated tailings can be categorized into physical, chemical, and biological improvements. Physical improvement mainly relies on the fine particles of pre-treated tailings and sludge, which helps increase the specific surface area, providing more contact area and reaction conditions, thus improving the contact and mixing degree between materials and promoting subsequent chemical and biological improvements. Chemical improvement involves the interaction of organic matter and metal ions in the wastewater treatment sludge with the chemical components in the tailings, resulting in reactions such as dissolution, adsorption, and ion exchange. This helps change the structure and composition of the tailings, further reducing the content of organic pollutants and fixing or releasing metal ions. Biological remediation leverages the rich microbial community within sludge, some of which possess the ability to decompose organic matter and transform metal ions, thus improving tailings properties and promoting the decomposition and removal of organic matter, as well as the transformation and fixation of metal ions. Therefore, by mixing pretreated wastewater sludge with pretreated tailings, tailings remediation is achieved through physical, chemical, and biological interactions, involving changes in particle size, chemical reactions, and microbial activity.

[0028] (2) Wood chip bio-fermentation treatment

[0029] Wood chips are prepared as raw material. Specific microbial agents with heat resistance and decomposition capabilities (high-temperature biological agents) are selected. The agent dosage, temperature, and ventilation conditions are set, and the wood chips are subjected to biological drying and composting (biological composting) treatment at specific intervals to obtain fermented wood chips. The decomposing agents can break down complex organic compounds in the wood chips, such as cellulose, hemicellulose, and lignin; the heat-resistant agents continue to play a role during the fermentation and heating process. During the biological drying and composting of the wood chips, the microbial agents decompose lignocellulose and organic matter, producing a series of degradation products, such as organic acids and volatile compounds, thereby altering the properties of the wood chips.

[0030] (3) The bioequilibrium of artificial soil uses improved tailings and fermented sawdust as raw materials, mixed in a certain proportion with an appropriate amount of water (tap water), and placed in a natural environment. Temperature, humidity, and light conditions are controlled to allow for a natural equilibrium process over a certain period. The bioequilibrium cycle is determined by measuring the characteristics of artificial soil aggregates, microbial biomass carbon and ATP, heavy metal availability, and basic physicochemical parameters. The introduction of fermented sawdust can further alter the physical, chemical, and biological properties of the improved tailings, giving it the functions of artificial soil. At the physical level, the microbial metabolites and organic matter in the fermented sawdust can promote immediate adsorption and binding of tailings, forming aggregates, improving the structure and porosity of the tailings, facilitating water penetration and retention, and enhancing the water retention and permeability of the artificial soil. Furthermore, the organic matter in the fermented sawdust forms a gel-like substance after mixing with the improved tailings, increasing particle cohesion and erosion resistance. At the physical level, this alters the water stability of the improved tailings artificial soil, reducing the risk of water and wind erosion. At the chemical level, the organic acids in fermented sawdust can regulate and improve the pH value of tailings, which is beneficial to the growth and activity of soil microorganisms. Furthermore, the nutrients (nitrogen, phosphorus, and potassium, etc.) contained in the microbial metabolism and organic matter of fermented sawdust are released into the tailings through microbial degradation and mineral transformation, providing a necessary nutrient source for subsequent plant growth in the artificial soil. At the biological level, fermented sawdust contains a rich microbial community. By mixing fermented sawdust with tailings, a microbial community with degradation capabilities and soil-forming functions is introduced into the tailings. The metabolic products and enzyme secretion of these microorganisms can promote the transformation of tailings and the soil-forming process, forming artificial soil with good ecological functions. In summary, fermented sawdust promotes the soil-forming process of tailings-improved artificial soil by influencing the physical, chemical, and biological properties of the soil, improving soil structure, water stability, chemical properties, and nutrient supply, thereby realizing the transformation of tailings into soil with good ecological functions.

[0031] (4) Vegetation reclamation

[0032] Select drought-tolerant and nutrient-poor plants such as tall fescue, planting at a density of 10-20 seeds per square meter at a depth of 1-2 cm. Irrigate 1-2 times per week, depending on environmental conditions and plant needs. Additionally, apply 80g of organic fertilizer and 10g of inorganic fertilizer per square meter. After the growing cycle, harvest the plants for recycling.

[0033] Example 1

[0034] (1) Gold tailings mixing treatment

[0035] a. Gold tailings pretreatment: The gold tailings are soaked in a 0.5% sodium hydroxide solution for 1 hour. The ratio of gold tailings to sodium hydroxide solution is 100:10 to reduce organic pollutants on the surface.

[0036] b. Wastewater treatment sludge pretreatment: The sludge is dewatered using a dryer at a temperature of 65℃ for 2 hours. It is then ground to about 0.25mm using a grinder to improve the efficiency and uniformity of tailings modification.

[0037] c. Raw material composition: Pretreated gold tailings and wastewater treatment sludge, in a dry weight ratio of 90:10.

[0038] d. Mixing gold tailings with sludge: The mixture was heated to 80°C and stirred for 40 minutes in a mixing tank to obtain the modified gold tailings.

[0039] (2) Wood chip bio-fermentation treatment

[0040] The sawdust was crushed to a particle size of less than 2 mm using a screw press, and then ultra-high temperature fermentation inoculants were added: Aspergillus aculeatus (CGMCC: 3.15668), Streptomyces albus (CGMCC: 4.7658), Bacillus megaterium (CGMCC: 1.8802), and Cellulomonas fimi (CGMCC: 1.1900) (composition ratio 1:2:1:3). The inoculum size was 2 × 10⁻⁶. 7 The sawdust was fermented at 80℃ with a concentration of CFU / g (effective viable bacteria). The fermentation process was repeated with a cycle of 10 min forward rotation, 20 min stop, 10 min reverse rotation, and 20 min stop. Aeration was set at 0.2 L / (kg·min), and the fermentation cycle was 14 days. The culture medium for the ultra-high temperature fermentation agent was CYS medium with the following formula: yeast extract 4.0 g / L, acid-hydrolyzed casein 6.0 g / L, soluble starch 3.0 g / L, sodium chloride 3.0 g / L, magnesium chloride hexahydrate 0.27 g / L, calcium chloride 0.025 g / L, ferrous sulfate heptahydrate 0.01 g / L, and trace elements 100 μL / L. The types and concentrations of trace elements added to the culture medium are as follows: Na₂MoO₄·2H₂O 12.0 g / L, VOSO₄·xH₂O 1.0 g / L, MnCl₂·4H₂O 7.86 g / L, ZnSO₄·7H₂O 0.6 g / L, CuSO₄·5H₂O 0.15 g / L, CoCl₂·6H₂O 8.0 g / L, and NiCl₂·6H₂O 0.01 g / L.

[0041] (3) Biological balance of artificial soil

[0042] Improved gold tailings and fermented sawdust were used as raw materials, thoroughly mixed at a ratio of 100:10, and subjected to biological equilibrium under artificial conditions. These conditions included cycles of 21℃-12h and 25℃-12h, light conditions of 0 lux-12h and 8000 lux-12h, and environmental humidity controlled at 75%. Tap water was added every 5 days to maintain a moisture content of 15-20%. Microbial biomass carbon, ATP, and aggregates were measured during the biological equilibrium process, and the biological equilibrium cycle was determined to be 150 days. The resulting artificial soil was set at a thickness of 10cm.

[0043] (4) Vegetation reclamation

[0044] Select drought-tolerant and nutrient-poor plants such as tall fescue, planting at a density of 10-20 seeds per square meter at a depth of 1-2 cm. Irrigate 1-2 times per week, depending on environmental conditions and plant needs. Additionally, apply 80g of organic fertilizer and 10g of inorganic fertilizer per square meter. After the growing cycle, harvest the plants for recycling.

[0045] Comparative Example 1

[0046] The difference between this comparative example and Example 1 is that pretreated wastewater sludge was not added. Other steps and parameters are the same as in Example 1.

[0047] Comparative Example 2

[0048] The difference between this comparative example and Example 1 is that no bio-fermented sawdust was added. All other steps and parameters are the same as in Example 1.

[0049] Comparative Example 3

[0050] The difference between this comparative example and Example 1 is that pretreated wastewater sludge and bio-fermented sawdust were not added.

[0051] Performance checks and results analysis:

[0052] The artificial soils prepared in Example 1 and Comparative Examples 1-3 were subjected to tests on aggregate structure, microbial carbon content, ATP content, available heavy metals, basic physicochemical properties, and germination rate of tall fescue seeds. The results are shown in Tables 1-5 below:

[0053] Table 1. Aggregate structure of artificial soil (%)

[0054]

[0055]

[0056] Table 2 Microbial biomass carbon and ATP content in artificial soil

[0057]

[0058] Table 3. Available states of heavy metals in artificial soil

[0059]

[0060] Table 4 Basic Physicochemical Properties of Artificial Soil

[0061]

[0062] Table 5 Germination rate of tall fescue seeds in artificial soil

[0063]

[0064] In Table 1-5, “a”, “b”, “c”, “d”, and “ab” represent significant differences between groups, with p < 0.05.

[0065] Table 1 shows that, in Comparative Example 1, the aggregate properties of the improved gold tailings without wastewater treatment sludge were improved compared to Example 1. The proportion of >2mm aggregates increased, the proportion of 0.25-2mm aggregates increased, the proportion of 0.035-0.25mm aggregates decreased, and the proportion of <0.035mm aggregates increased. This indicates that the addition of wastewater treatment sludge has a positive effect on improving the aggregate properties of the gold tailings. In Comparative Example 2, the aggregate properties of the improved gold tailings without the addition of fermented and decomposed sawdust were improved compared to Example 1. The proportion of >2mm aggregates increased, the proportion of 0.25-2mm aggregates increased significantly, the proportion of 0.035-0.25mm aggregates increased slightly, and the proportion of <0.035mm aggregates decreased slightly. This indicates that the addition of fermented and decomposed sawdust further improved the aggregate properties of the gold tailings. In Comparative Example 3, the aggregate properties of the improved gold tailings, without the addition of either wastewater treatment sludge or fermented and decomposed sawdust, were lower than those in Example 1 and Comparative Example 2. The proportion of aggregates >2mm was 0, the proportion of aggregates between 0.25-2mm increased, the proportion of aggregates between 0.035-0.25mm decreased, and the proportion of aggregates <0.035mm increased. This indicates that the addition of wastewater treatment sludge and fermented and decomposed sawdust significantly improved the aggregate properties of the gold tailings. This demonstrates that the addition of wastewater treatment sludge and fermented sawdust has a positive effect on improving the aggregate properties of gold tailings. The addition of wastewater treatment sludge increased the formation of large aggregates, while the addition of fermented and decomposed sawdust further improved the distribution and uniformity of the aggregates. These improvement measures contribute to improving the soil properties and sustainable utilization of gold tailings.

[0066] Table 2 shows that in Comparative Example 1, the microbial biomass carbon of the improved gold tailings without wastewater treatment sludge was 316.87 mg / kg, and the ATP content was 0.245 nmol / g. Compared with Example 1, the microbial biomass carbon and ATP content were slightly reduced. This indicates that the addition of wastewater treatment sludge has a certain increasing effect on the microbial biomass and activity of the gold tailings. In Comparative Example 2, the microbial biomass carbon of the improved gold tailings without the addition of fermented and decomposed sawdust was 83.39 mg / kg, and the ATP content was 0.074 nmol / g. Compared with Example 1 and Comparative Example 1, the microbial biomass carbon and ATP content were significantly reduced. This indicates that the addition of fermented and decomposed sawdust has an important promoting effect on the microbial biomass and activity of the gold tailings. In Comparative Example 3, the microbial biomass carbon of the improved gold tailings without the addition of either wastewater treatment sludge or fermented and decomposed sawdust was 32.48 mg / kg, and the ATP content was 0.062 nmol / g. Compared with Example 1 and Comparative Examples 1 and 2, the microbial biomass carbon and ATP content were further reduced. This indicates that the addition of wastewater treatment sludge and fermented sawdust has a significant improving effect on the microbial biomass and activity of gold tailings.

[0067] Table 3 shows that in Comparative Example 1, the bioavailable Cd content of the improved gold tailings without wastewater treatment sludge was 0.193 mg / kg, the bioavailable Cu content was 1.063 mg / kg, the bioavailable Pb content was 2.754 mg / kg, and the bioavailable Zn content was 4.015 mg / kg. Compared with Example 1, the bioavailable Cd and Cu contents increased slightly, while the bioavailable Pb and Zn contents remained largely unchanged. This indicates that the addition of wastewater treatment sludge has a certain impact on the heavy metal content of the gold tailings, which may lead to a slight increase in Cd and Cu. In Comparative Example 2, the bioavailable Cd content of the improved gold tailings without the addition of fermented and decomposed sawdust was 0.254 mg / kg, the bioavailable Cu content was 1.083 mg / kg, the bioavailable Pb content was 3.861 mg / kg, and the bioavailable Zn content was 4.519 mg / kg. Compared to Example 1 and Comparative Example 1, the bioavailable contents of Cd, Cu, and Zn increased, while the bioavailable contents of Pb increased significantly. This indicates that the addition of fermented and decomposed sawdust has a certain impact on the heavy metal content of gold tailings, potentially leading to an increase in Cd, Cu, and Zn, as well as a significant increase in Pb. In Comparative Example 3, the bioavailable contents of the improved gold tailings, without the addition of either wastewater treatment sludge or fermented and decomposed sawdust, were 0.293 mg / kg for Cd, 1.492 mg / kg for Cu, 3.956 mg / kg for Pb, and 6.163 mg / kg for Zn. Compared to Example 1 and Comparative Examples 1 and 2, the bioavailable contents of Cd, Cu, and Pb increased, while the bioavailable contents of Zn increased significantly. This indicates that the addition of wastewater treatment sludge and fermented sawdust has a significant improving effect on the heavy metal content of gold tailings, potentially leading to an increase in Cd, Cu, and Pb, as well as a significant increase in Zn. The results indicate that the addition of sewage treatment sludge and fermented sawdust has a significant effect on improving the heavy metal content of gold tailings. The addition of sewage treatment sludge may lead to a slight increase in Cd and Cu, while the addition of fermented and decomposed sawdust may lead to an increase in Cd, Cu, and Zn, as well as a significant increase in Pb. These improvement measures help to regulate the heavy metal content of gold tailings and promote the environmental safety and sustainable utilization of gold tailings.

[0068] Table 4 shows that in Comparative Example 1, compared with Example 1, the pH value was slightly lower, the organic matter content was slightly higher, the total nitrogen content was significantly lower, the total phosphorus content was slightly higher, and the available potassium content was slightly higher. This indicates that the addition of sewage treatment sludge has a certain impact on the pH value, organic matter content, total nitrogen content, and available potassium content of the gold tailings, and may lead to a decrease in pH value and an increase in organic matter content. In Comparative Example 2, compared with Example 1 and Comparative Example 2, the pH value was slightly higher, the organic matter content was significantly lower, the total nitrogen content was slightly higher, the total phosphorus content was slightly higher, and the available potassium content was slightly lower. This indicates that the addition of fermented and decomposed sawdust has a certain impact on the pH value, organic matter content, total nitrogen content, and total phosphorus content of the gold tailings, and may lead to an increase in pH value and a decrease in organic matter content. In Comparative Example 3, compared with Example 1 and Comparative Examples 1 and 2, the pH value was significantly lower, the organic matter content was significantly lower, the total nitrogen content was significantly lower, the total phosphorus content was slightly higher, and the available potassium content was significantly lower. This indicates that the addition of wastewater treatment sludge and fermented sawdust has a significant impact on the pH, organic matter content, total nitrogen content, and available potassium content of gold tailings. It may lead to a significant decrease in pH and organic matter content, a significant decrease in total nitrogen content, a slight increase in total phosphorus content, and a significant decrease in available potassium content. This demonstrates that wastewater treatment sludge and fermented sawdust have a certain modifying effect on the basic physicochemical properties of gold tailings. The addition of wastewater treatment sludge may lead to a decrease in pH and an increase in organic matter content, while the addition of fermented sawdust may lead to an increase in pH and a decrease in organic matter content. These modifying measures have different degrees of impact on the physicochemical properties of gold tailings, which is of great significance to the environmental safety and sustainable utilization of gold tailings.

[0069] Table 5 shows that, compared with Example 1, the germination rate of Comparative Example 1 was lower, indicating that the addition of sewage treatment sludge had a positive impact on the germination rate of tall fescue seeds, possibly improving the suitability of gold tailings and the success rate of seed germination. In Comparative Example 2, the germination rate was slightly higher than that of Example 1, indicating that the addition of fermented sawdust may have a positive impact on the germination rate of tall fescue seeds, providing suitable growth conditions and contributing to seed germination and plant growth. Compared with Example 1 and Comparative Examples 1 and 2, the germination rate of Comparative Example 3 was significantly lower, indicating that the addition of sewage treatment sludge and fermented sawdust had a significant positive impact on the germination rate of tall fescue seeds, possibly providing a better growth environment and nutrient supply, promoting seed germination and plant growth. These results demonstrate that sewage treatment sludge and fermented sawdust have a positive impact on the germination rate during the soil improvement process of gold tailings. These improvement measures help provide suitable growth conditions, improve the growth environment of plant seeds, and promote plant growth and greening effects.

[0070] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing artificial soil based on tailings modification, characterized in that, The process includes the following steps: Step 1: Wash and soak the tailings with a weak alkaline solution to obtain pretreated tailings; The sludge is dewatered and then ground to a suitable particle size using a grinding equipment to obtain pretreated sludge. The pretreated tailings and pretreated sludge are mixed in a certain proportion to obtain modified tailings; wherein, the mass ratio of the pretreated tailings to the pretreated sludge is 9:1; the mixing time of the pretreated tailings and pretreated sludge is 40 min, and the temperature is 80℃; Step 2: Under a specific cycle, the sawdust is subjected to biological drying and composting treatment using a specific microbial agent with high temperature resistance and decomposition ability to obtain biologically fermented sawdust; wherein, the temperature of the biological drying and composting treatment is 80℃; the culture medium for the biological drying and composting treatment is CYS culture medium; the parameters of the biological drying and composting treatment are: forward rotation for 10 min, stop for 20 min, reverse rotation. Step 3: Using modified tailings and bio-fermented sawdust as raw materials, mix them in a certain proportion and add an appropriate amount of water. Place them in a natural environment and control the temperature, humidity and light conditions to carry out a natural equilibrium process for a certain period of time to obtain artificial soil based on tailings modification. The temperature, humidity and light conditions are as follows: Temperature: 21℃-12h and 25℃-12h cycle; Humidity: replenish tap water every 5 days to maintain a moisture content of 15-20%; Humidity control is 75%; Light conditions: 0 lux-12h and 8000 lux-12h.

2. The method for preparing artificial soil based on tailings modification according to claim 1, characterized in that, In step 1, the weak alkaline solution is a 0.5% sodium hydroxide solution, and the mass ratio of the tailings to the sodium hydroxide solution is 10:

1.

3. The method for preparing artificial soil based on tailings modification according to claim 1, characterized in that, In step 1, the dehydration treatment is carried out at a temperature of 65°C for 2 hours; the suitable particle size has a diameter of 0.2-0.3 mm.

4. The method for preparing artificial soil based on tailings modification according to claim 1, characterized in that, In step 2, the specific microbial agent with heat resistance and decomposition ability is a mixed bacteria, which includes Aspergillus, thermophilic aerobic bacteria, Bacillus, and Fibriocarpus.

5. The method for preparing artificial soil based on tailings modification according to claim 1, characterized in that, In step 3, the ratio of the modified tailings to the wood chips after bio-fermentation is 10:

1.

6. The method for preparing artificial soil based on tailings modification according to claim 1, characterized in that, The formulation of the CYS medium is as follows: yeast extract 4.0 g / L, acid-hydrolyzed casein 6.0 g / L, soluble starch 3.0 g / L, sodium chloride 3.0 g / L, magnesium chloride hexahydrate 0.27 g / L, calcium chloride 0.025 g / L, ferrous sulfate heptahydrate 0.01 g / L, and trace elements 100 μL / L. The CYS medium contains the following trace elements: MoO4·2H2O 12.0 g / L, VOSO4·xH2O 1.0 g / L, MnCl2·4H2O 7.86 g / L, ZnSO4·7H2O 0.6 g / L, CuSO4·5H2O 0.15 g / L, CoCl2·6H2O 8.0 g / L, and NiCl2·6H2O 0.01 g / L.

7. An artificial soil based on tailings modification, characterized in that, The tailings-modified artificial soil is obtained using the preparation method described in any one of claims 1-6.

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