Method for ecological restoration using neutralization slag

Abstract

The present invention provides a method for ecological restoration using neutralization slag, which relates to the technical fields of environmental protection and ecological restoration. The method includes mixing the neutralization slag evenly with microbial inoculum and nutrients, and then laying it on the surface of the acidic medium layer of the mine to form a neutralization slag isolation layer; evenly laying first waste rocks with a predetermined particle size on the surface of the neutralization slag isolation layer to form a waste rock isolation layer; mixing the neutralization slag with flotation tailings, second waste rocks, and soil to form a planting substrate, and mixing the planting substrate evenly with grass seeds and organic matter in a predetermined proportion, and then laying it on the surface of the waste rock isolation layer to form a vegetation growth layer; laying an ecological restoration protection layer on the surface of the prepared growth layer. Through the above method, the present invention sequentially lays a neutralization slag isolation layer, a waste rock isolation layer, a vegetation growth layer, and an ecological restoration protection layer on the acidic medium surface of the mine, and reasonably designs the composition of the raw materials of each layer to increase the vegetation coverage rate of ecological restoration, while reducing the generation of acidic water and the degree of wastewater pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection and ecological restoration, and particularly to a method for ecological restoration using neutralization slag. Background Art

[0002] Sulfur-rich deposits in non-ferrous metal mines contain a large amount of sulfide minerals. Under the action of air, water and microorganisms, a series of physical and chemical and biochemical reactions such as weathering, leaching, oxidation and hydrolysis occur, gradually forming acidic liquids containing sulfuric acid. At present, these acidic liquids are usually treated by the lime neutralization method. Although the wastewater can meet the discharge standards, a large amount of neutralization slag needs to be stored, occupying a large amount of land and greatly increasing the operating cost and construction investment of acidic water treatment. Therefore, the disposal and utilization of neutralization slag are gradually becoming a major problem.

[0003] At the same time, during the ecological restoration process of non-ferrous metal mines, there is a general shortage of "imported soil". Moreover, the ordinary imported soil method is affected by the original acidic medium in the mine and cannot effectively guarantee the vegetation coverage rate of ecological restoration for a long time. It is necessary to add a certain amount of pH modifier to the soil irregularly to ensure the ecological restoration effect, greatly increasing the difficulty and investment of ecological restoration. If the neutralization slag can be used for ecological restoration, it is of great significance for the disposal and utilization of neutralization slag and ecological restoration.

[0004] In the prior art, the patent with the publication number CN112958579A provides a copper mine acidic yard ecological restoration system and method, which mainly uses neutralization slag to carry out ecological restoration on the copper heap leaching yard. By pre-treating the copper heap leaching yard by leaching, and then sequentially setting a barrier layer, a vegetation restoration layer and a protection layer, not only can the ecological restoration and treatment of the heap leaching heap be realized, but also a new way is provided for the resource utilization of neutralization slag and the secondary pollution problem of heap leaching slag acidic wastewater. However, this patent can only be applied to copper slag yards at present. During the setting process of the barrier layer and the vegetation restoration layer, the neutralization slag has a potential risk of polluting the environment, and cannot effectively control the generation of acidic water and pollutants. At the same time, it will also affect the air permeability of the soil, thereby affecting the growth of vegetation.

[0005] In view of this, it is necessary to design an improved method for ecological restoration using neutralization slag to solve the above problems. Summary of the Invention

[0006] Aiming at the defects of the above-mentioned prior art, the purpose of the present invention is to provide a method for ecological restoration using neutralization slag. By reasonably designing the composition, ratio and restoration method of each layer of raw materials in the ecological restoration process, while improving the vegetation coverage rate of ecological restoration, the generation of acidic water and the degree of wastewater pollution in the ecological restoration area of non-ferrous metal mines are greatly reduced.

[0007] To achieve the above object, the present invention provides a method for ecological restoration using neutralization slag, comprising the following steps:

[0008] S1. After uniformly mixing the qualified neutralization slag with microbial inoculum and its nutrients, lay it on the surface of the acidic medium layer of the mine to form a neutralization slag isolation layer;

[0009] S2. Uniformly lay the first waste rock with a predetermined particle size on the surface of the neutralization slag isolation layer to form a waste rock isolation layer;

[0010] S3. Mix the qualified neutralization slag with flotation tailings, the second waste rock, and soil to form a planting substrate, and after uniformly mixing the planting substrate with grass seeds and organic matter in a predetermined proportion, lay it on the surface of the waste rock isolation layer to form a vegetation growth layer;

[0011] S4. Lay an ecological restoration protection layer on the surface of the prepared growth layer.

[0012] As a further improvement of the present invention, the qualified neutralization slag is as follows: the neutralization slag meets the requirements of Class I general industrial solid waste, and the liquid phase of the neutralization slag meets the discharge requirements, and the pH of the liquid phase of the neutralization slag is 8.5 - 9.0.

[0013] As a further improvement of the present invention, when the neutralization slag does not meet the requirements, the neutralization slag is first pretreated; the pretreatment methods include:

[0014] Dissolve the neutralization slag with an acidic solution and make the pH value of the obtained neutralization slag turbid liquid be 2.8 - 3.2. After fully stirring and reacting for 1.5 - 2.5 h, perform the first solid-liquid separation treatment to obtain the first solid slag and the first liquid; among them, the first solid slag is managed as hazardous waste;

[0015] Adjust the pH value of the first liquid to between 8.5 - 9.0 with an alkaline substance. After fully reacting for 1.5 - 2.5 h, perform the second solid-liquid separation to obtain the second solid slag and the second liquid; the second solid slag is the neutralization slag that meets the requirements of Class I general industrial solid waste, and the second liquid is used for recycling the neutralization slag pretreatment or discharging up to standard.

[0016] As a further improvement of the present invention, in step S1, the mass ratio of the qualified neutralization slag, microbial inoculum, and nutrients is 1 kg: 0.1 - 2 mg: 1 - 10 g.

[0017] As a further improvement of the present invention, in step S1, the microbial inoculum is sulfate-reducing bacteria, and the nutrients are one or a mixture of several of domestic sewage activated sludge, straw, and feces.

[0018] As a further improvement of the present invention, in step S1, the thickness of the neutralization slag isolation layer is 0.1 - 0.3 m.

[0019] As a further improvement of the present invention, in step S2, the particle size of the first waste rock is 4 - 6 cm, and the thickness of the waste rock isolation layer is 0.05 - 0.15 m.

[0020] As a further improvement of the present invention, in step S3, in the planting substrate, the mass ratio of the qualified neutralization slag, flotation tailings, second waste rock, and soil is: 100:10 - 50:10 - 50:10 - 50; the mass ratio of the planting substrate, grass seeds, and organic matter is 100:1 - 5:0.01 - 0.1.

[0021] As a further improvement of the present invention, in step S3, the particle size of the flotation tailings is 0.01 - 0.3 mm, and the particle size of the second waste rock is less than 1.5 cm; after the planting substrate, grass seeds, and organic matter are mixed, mechanical stirring and screening are also carried out, and the screening particle size is less than 3 cm, and the undersize is used as mechanical spraying material for mechanical spraying.

[0022] As a further improvement of the present invention, in step S4, the ecological restoration protection layer is non-woven fabric.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. The method for ecological restoration using neutralization slag provided by the present invention can effectively improve the vegetation coverage rate of ecological restoration and greatly reduce the generation of acidic water and the degree of wastewater pollution in the ecological restoration area of non-ferrous metal mines by successively laying a neutralization slag isolation layer, a waste rock isolation layer, a vegetation growth layer, and an ecological restoration protection layer on the surface of the acidic medium in the mine and reasonably setting the composition and ratio of the raw materials of each layer.

[0025] 2. The method for ecological restoration using neutralization slag provided by the present invention can not only treat waste with waste, but also improve the stress condition of the neutralization slag isolation layer and thus improve the structural stability of the neutralization slag isolation layer by adding sulfate-reducing bacteria to the neutralization slag isolation layer and adding domestic sewage activated sludge, straw, feces, etc. as nutrients, through the adhesion of nutrients such as activated sludge and feces and the fiber structure of straw. At the same time, in the vegetation growth layer of the present invention, by using the neutralization slag, flotation tailings, waste rock, and soil as the planting substrate together, it can not only improve the utilization rate of waste such as neutralization slag, flotation tailings, and waste rock, but also improve the porosity of the vegetation growth layer, increase the air permeability of the vegetation growth layer, and further improve the vegetation coverage rate after ecological restoration.

[0026] 3. The method for ecological restoration using neutralization slag provided by the present invention is simple to operate, safe and reliable. It uses waste materials such as neutralization slag, flotation tailings, and waste rock to achieve the purpose of treating waste with waste. It can not only achieve the ecological restoration of non-ferrous mines, but also alleviate the generation of acidic water from the source, with significant environmental and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram formed after ecological restoration according to the method provided by the present invention.

[0028] REFERENCE NUMERALS

[0029] 1 - Acidic medium layer of the mine; 2 - Neutralization slag isolation layer; 3 - Waste rock isolation layer; 4 - Vegetation growth layer; 5 - Ecological restoration protection layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the drawings and specific embodiments.

[0031] Here, it should also be noted that in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, while other details less related to the present invention are omitted.

[0032] In addition, it should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0033] The present invention provides a method for ecological restoration using neutralization slag, including the following steps:

[0034] S1. Mix the qualified neutralization slag with microbial inoculants and their nutrients evenly, and then lay it on the surface of the acidic medium layer 1 of the mine to form a neutralization slag isolation layer 2;

[0035] S2. Uniformly lay the first waste rock with a predetermined particle size on the surface of the neutralization slag isolation layer 2 to form a waste rock isolation layer 3;

[0036] S3. Mix the qualified neutralization slag with flotation tailings, the second waste rock, and soil to form a planting substrate, and then mix the planting substrate, grass seeds, and organic matter evenly according to a predetermined ratio, and lay it on the surface of the waste rock isolation layer 3 to form a vegetation growth layer 4;

[0037] S4. Lay an ecological restoration protection layer 5 on the surface of the vegetation growth layer 4, and the final structural schematic diagram is as shown in Figure 1 the following figure.

[0038] By the above method, the present invention can successively lay a neutralization slag isolation layer 2, a waste rock isolation layer 3, a vegetation growth layer 4 and an ecological restoration protection layer 5 on the surface of the acidic medium layer 1 of the mine. Through the reasonable design of the composition and ratio of the raw materials of each layer, the ecological restoration vegetation coverage rate can be effectively improved, and at the same time, the generation of acidic water and the degree of wastewater pollution in the ecological restoration area of non-ferrous mines can be greatly reduced.

[0039] More specifically, the acidic medium of the mine is ores, waste rocks and waste dumps rich in sulfide ores that are prone to generate acidic water, etc. The neutralization slag is the neutralization slag generated during the treatment of mine acidic water, mainly including calcium sulfate, metal hydroxides, etc. The water content of the neutralization slag is less than or equal to 65%. The neutralization slag needs to meet the requirements of Class I general industrial solid waste, and the liquid phase of the neutralization slag meets the first-class emission standards of the Comprehensive Wastewater Discharge Standard (GB 8978-1996) and the direct discharge limit requirements specified in the Discharge Standards for Pollutants from Copper, Cobalt and Nickel Industries (GB 25467-2010) to meet the discharge requirements, and preferably the pH of the liquid phase of the neutralization slag is 8.5-9.0.

[0040] When the neutralization slag does not meet the above requirements, it is necessary to pretreat the neutralization slag first.

[0041] The methods of the pretreatment include:

[0042] Dissolve the neutralization slag with acidic solutions such as sulfuric acid and acidic water, and make the pH value of the obtained neutralization slag turbid liquid 2.8-3.2. After fully stirring and reacting for 1.5-2.5 h, perform the first solid-liquid separation treatment to obtain the first solid slag and the first liquid; among them, the first solid slag is managed as hazardous waste;

[0043] Adjust the pH value of the first liquid to 8.5-9.0 with alkaline substances such as lime and sodium hydroxide. After fully reacting for 1.5-2.5 h, perform the second solid-liquid separation to obtain the second solid slag and the second liquid; the second solid slag is the neutralization slag that meets the requirements of Class I general industrial solid waste, and the second liquid is used for recycling the neutralization slag pretreatment or discharging up to standard.

[0044] When the pH value of the liquid phase of the neutralization slag is lower than 8.5, it is necessary to add a pH regulator to adjust the pH value of the liquid phase of the neutralization slag to 8.5-9.0; the pH regulator is preferably lime.

[0045] In step S1, the mass ratio of the qualified neutralization slag, microbial inoculant, and nutrients is 1 kg: 0.1 - 2 mg: 1 - 10 g; the microbial inoculant is preferably sulfate-reducing bacteria (SRB), which can react with sulfates on the surface of the mine acidic medium layer and in the neutralization slag to generate sulfides, and then react with metal ions to form a stable metal sulfide precipitation layer, playing a role in reducing the generation amount of pollutants and blocking the pollutant channels; the nutrients are preferably one or a mixture of domestic sewage activated sludge, straw, and feces, more preferably a mixture of at least one of domestic sewage activated sludge and feces and straw. This setting can not only treat waste with waste, but also improve the stress condition of the neutralization slag isolation layer through the adhesiveness of nutrients such as activated sludge and feces and the fiber structure of straw, thereby improving the structural stability of the neutralization slag isolation layer. The thickness of the neutralization slag isolation layer 2 is adjusted according to the pH value of the mine acidic medium. When the pH of the acidic water generated by the mine acidic medium is between 1 and 4, the thickness of the neutralization slag isolation layer 2 is preferably 0.1 - 0.3 m. With this setting, the microbial inoculant in the neutralization slag isolation layer 2 can not only react to generate sulfides to reduce the concentration of heavy metal pollutants, but also effectively block the circulation of the acidic medium and the external environment. In an anaerobic environment, it can not only reduce the generation of acidic water, but also block the outward flow of the generated acidic water.

[0046] In step S1, an adhesive can also be added, and the dosage of the adhesive can be adjusted according to the size of the slope of the mine acidic medium, being directly proportional to the size of the slope.

[0047] In step S2, the first waste rock is the waste rock generated during the flotation process of non-ferrous metal mines, with a particle size of 4 - 6 cm, and the thickness of the waste rock isolation layer 3 is 0.05 - 0.15 m. This setting can avoid sulfate-reducing bacteria from entering the plant growth layer, thereby reducing the possibility of reacting with sulfates in the plant growth layer to generate sulfides and ensuring the normal growth of plants; at the same time, sulfates and metal ions in the waste rock can also penetrate into the neutralization slag isolation layer 2 to react with sulfate-reducing bacteria to reduce the generation of pollutants and effectively improve the utilization rate of the waste rock.

[0048] In step S3, in the planting substrate, the mass ratio of the qualified neutralization slag, flotation tailings, second waste rock, and soil is: 100: 10 - 50: 10 - 50: 10 - 50; the mass ratio of the planting substrate, grass seeds, and organic matter is 100: 1 - 5: 0.01 - 0.1.

[0049] Among them, the organic matter can be one or more of waste materials such as organic fertilizers, compound fertilizers, biological method surplus sludge, straw powder, and their fermentation products; the grass seeds are mainly one or more of pigeon pea, tephrosia candida, bermudagrass, ryegrass, elymus dahuricus, and velvet grass. The flotation tailings and the second waste rock are the tailings and waste rock generated during the flotation process of non-ferrous metal mines. The water content of the flotation tailings and the second waste rock is less than or equal to 35%, and both the flotation tailings and the second waste rock need to meet the requirements of Class I general industrial solid waste. The particle size of the flotation tailings is 0.01 - 0.3 mm, and the particle size of the waste rock is less than 1.5 cm. With such a setting, not only can the utilization rate of waste materials such as neutralization slag, flotation tailings, and waste rock be improved, but also the porosity of the vegetation growth layer can be improved, the air permeability of the vegetation growth layer 4 can be increased, and thus the vegetation coverage rate after ecological restoration can be increased.

[0050] The laying method of the vegetation growth layer 4 can be manual hole sowing or mechanical spraying. If mechanical spraying is adopted, after the planting substrate is mixed with grass seeds and organic matter, mechanical stirring and screening are also required. The screening particle size is less than 3 cm, and the undersize is used as mechanical spraying material for mechanical spraying.

[0051] In the vegetation growth layer 4, an adhesive can also be added. The dosage of the adhesive can be adjusted according to the size of the slope of the acidic medium in the mine, and is proportional to the slope size. The thickness of the vegetation growth layer 4 is preferably 0.2 - 0.6 m.

[0052] In step S4, the ecological restoration protection layer 5 is a non-woven fabric, preferably an environmentally friendly non-woven fabric.

[0053] The following will illustrate a method for ecological restoration using neutralization slag provided by the present invention in combination with specific embodiments.

[0054] Example 1

[0055] This example provides a method for ecological restoration using neutralization slag. This method is aimed at a non-ferrous metal mine in the south where sulfide minerals are rich around the mine. A large amount of acidic wastewater is generated due to leaching and other effects in the waste rock of the waste dump, and pollutants such as copper and iron in the acidic wastewater exceed the standards seriously. The existing vegetation coverage rate of the entire waste dump is relatively low (less than 15%). The method for ecological restoration using neutralization slag provided in this example specifically includes the following steps:

[0056] S1. Lay the neutralization slag isolation layer 2. In this embodiment, the pH of the acidic water generated by the mine acidic medium is 2.6. After the mine acidic water is treated by the traditional neutralization process, the wastewater reaches the first-class discharge standard of "Integrated Wastewater Discharge Standard" (GB 8978-1996). The pH value of the liquid phase of the neutralization slag produced by pressure filtration is between 8.5 and 9.0, and the water content is about 50%. The main components are calcium sulfate and metal hydroxides, meeting the requirements of Class I general industrial solid waste (if the requirements are not met, pretreatment is required first, and after the treated neutralization slag meets the requirements, it can be used for ecological restoration). Sulfate-reducing bacteria SRB bio-agent is added to the neutralization slag, and the dosage is 0.5 mg per kilogram of neutralization slag. At the same time, nutrients composed of domestic sewage activated sludge (with a water content of about 85%) and straw mixed in a mass ratio of 1:1 are incorporated. The dosage of the nutrients is 5 g per kilogram of neutralization slag. After mixing evenly, the formed neutralization slag isolation layer 2 is evenly laid on the surface of the mine acidic medium layer 1, and the total laying thickness of the neutralization slag isolation layer 2 is 0.2 m.

[0057] S2. Lay the waste rock isolation layer 3. Lay the first waste rock with a particle size of about 5 cm on the top of the neutralization slag isolation layer 2, and the thickness of the waste rock isolation layer 3 is 0.1 m.

[0058] S3. Lay the vegetation growth layer 4. The vegetation growth layer 4 includes neutralization slag generated from acidic water treatment, copper flotation tailings (the particle size is mainly concentrated between 0.15 and 0.25 mm), second waste rock (the particle size is 1 - 1.5 cm), local surface stripped soil, organic matter and grass seeds. Among them, the mass ratio of neutralization slag, copper flotation tailings, second waste rock, and soil is 100:15:15:25. The formed planting substrate is then mixed with organic matter and grass seeds in a mass ratio of 100:2:0.02. After mechanical stirring, it passes through a vibrating screen with a particle size of 2 cm, and the screened material is planted by mechanical spraying. The thickness of the vegetation growth layer is controlled at 0.4 m. Among them, the organic matter is a mixture of organic fertilizer and compound fertilizer in a mass ratio of 1:1, and the grass seeds are a mixture of pigeon pea, mountain tick clover, and bermudagrass in a mass ratio of 1:1.

[0059] S4. Lay the ecological restoration protection layer 5. Just cover a layer of environmentally friendly non-woven fabric on the surface of the vegetation growth layer 4.

[0060] After one year of artificial maintenance and topdressing, the structure of this area is stable, and the production of acidic water has decreased significantly, from 140 m 3 / d to about 1 m 3 / d, the pollution levels of copper, iron, and pH value in the acidic water are significantly reduced. Before the remediation, the copper concentration in the acidic water reached approximately 100 mg / L, the iron concentration was about 300 mg / L, and the pH value was around 2.6. After the remediation, the target pollutants such as copper, iron, and pH can meet the first-class discharge standard of "Integrated Wastewater Discharge Standard" (GB 8978-1996); moreover, the vegetation coverage rate in this area reaches more than 73%.

[0061] Example 2

[0062] This example provides a method for ecological restoration using neutralization slag. This method is aimed at a non-ferrous metal mine in a certain northwest region where sulfide minerals are rich around the mine. Due to leaching and other effects, a large amount of acidic wastewater is generated from the waste rocks in the waste dump. The pollutants such as iron and manganese in the acidic water exceed the standard seriously, and the existing vegetation coverage rate of the entire waste dump is relatively low (less than 5%). The method for ecological restoration using neutralization slag provided in this example specifically includes the following steps:

[0063] S1. Laying the neutralization slag isolation layer 2. In this example, the pH of the acidic water generated by the acidic medium in the mine is 3.2. After the acidic water in the mine is treated by the HDS process, the wastewater meets the first-class discharge standard of "Integrated Wastewater Discharge Standard" (GB 8978-1996). The pH value of the liquid phase of the neutralization slag produced by pressure filtration is between 8.5 and 9.0, and the water content is about 55%. The main components are calcium sulfate and metal hydroxides, meeting the requirements of general industrial solid waste type I. Add the sulfate-reducing bacteria SRB biological agent to this neutralization slag, and the dosage is 1.5 mg per kilogram of neutralization slag. At the same time, incorporate the nutrient substance formed by mixing domestic sewage activated sludge (with a water content of about 85%) and straw in a mass ratio of 1:1. The dosage of the nutrient substance is 8 g per kilogram of neutralization slag. After mixing evenly, the formed neutralization slag isolation layer 2 is evenly laid on the surface of the mine acidic medium layer 1, and the total laying thickness of the neutralization slag isolation layer 2 is 0.3 m.

[0064] S2. Laying the waste rock isolation layer 3. Lay the first waste rock with a particle size of 5 cm on the top of the neutralization slag isolation layer 2, and the thickness of the waste rock isolation layer 3 is 0.15 m.

[0065] S3. Lay the vegetation growth layer 4. The vegetation growth layer 4 includes neutralization slag generated from acid water treatment, copper flotation tailings (with particle sizes mainly concentrated between 0.15 and 0.30 mm), second waste rock (with particle sizes of 0.5 - 1.0 cm), local surface stripped soil, organic matter, and grass seeds. Among them, the mass ratio of neutralization slag, copper flotation tailings, second waste rock, and soil is 100:25:25:50. The formed planting substrate is then mixed with organic matter and grass seeds according to a mass ratio of 100:5:0.10. After mechanical stirring, it is passed through a vibrating screen with a particle size of 3 cm, and the undersize is planted by mechanical spraying. The thickness of the vegetation growth layer is controlled at 0.6 m. Among them, the organic matter is a mixture of straw powder and compound fertilizer in a mass ratio of 1:1, and the grass seeds are a mixture of ryegrass, Elymus dahuricus, and velvet grass in a mass ratio of 1:1.

[0066] S4. Lay the ecological restoration protection layer 5. Just cover a layer of environment-friendly non-woven fabric on the surface of the vegetation growth layer 4.

[0067] After one year of artificial maintenance and topdressing, the structure of this area is stable, and the amount of acid water produced is significantly reduced, from 60 m 3 / d to about 0.5 m 3 / d. The pollution levels of copper, iron, and pH value in the acid water are significantly reduced. Before restoration, the copper concentration in the acid water reached about 50 mg / L, the iron concentration was about 80 mg / L, and the pH value was around 3.2. After restoration, target pollutants such as copper, iron, and pH can meet the first-class discharge standard of "Integrated Wastewater Discharge Standard" (GB 8978 - 1996); and the vegetation coverage rate in this area reaches more than 58%.

[0068] Comparative Examples 1 - 4

[0069] Comparative Examples 1 - 4 respectively provide a method for ecological restoration using neutralization slag. Compared with Example 1, the differences are that the dosage of microbial agents in the neutralization slag isolation layer, the dosage of nutrients, the thickness of the waste rock isolation layer, the solid waste properties of the neutralization slag, and the dosage of flotation tailings and second waste rock in the vegetation growth layer are respectively changed. The relevant parameters corresponding to each comparative example are shown in Table 1. The remaining steps and parameters are the same as those in Example 1 and will not be elaborated here.

[0070] Table 1 Process parameters in Comparative Examples 1 - 4

[0071]

[0072] After ecological restoration of the colored mine waste dump according to the methods provided in Comparative Examples 1 - 4 above, the amount of acid water produced, the degree of acid water pollution, and the vegetation coverage rate are detected. The results are shown in Table 2.

[0073] Table 2 Test results in Comparative Examples 1 - 4

[0074]

[0075] As can be seen from Table 2, on the basis of Example 1, adjusting the dosage of microbial inoculant, the dosage of nutrients, the thickness of the waste rock isolation layer or the composition of the planting substrate will all affect the amount of acidic water generated and the vegetation coverage rate of ecological restoration. The method for ecological restoration using neutralization slag provided by the present invention can effectively reduce the amount of acidic water generated and make the pollutants in the formed acidic water meet the discharge standards by adding a specific amount of microbial inoculant and nutrients to the neutralization slag isolation layer, setting a waste rock isolation layer with a specific thickness on the surface of the neutralization slag isolation layer, and adding a specific proportion of flotation tailings and secondary waste rock to the planting substrate. At the same time, it can effectively improve the vegetation coverage rate and achieve effective ecological restoration.

[0076] In summary, the present invention provides a method for ecological restoration using neutralization slag, which relates to the technical field of environmental protection and ecological restoration. The method includes mixing the neutralization slag with the microbial inoculant and its nutrients evenly and then laying them on the surface of the acidic medium layer of the mine to form a neutralization slag isolation layer; evenly laying the first waste rock with a predetermined particle size on the surface of the neutralization slag isolation layer to form a waste rock isolation layer; mixing the neutralization slag with flotation tailings, secondary waste rock and soil to form a planting substrate, and mixing the planting substrate with grass seeds and organic matter evenly according to a predetermined ratio and then laying them on the surface of the waste rock isolation layer to form a vegetation growth layer; laying an ecological restoration protection layer on the surface of the prepared growth layer. In this way, the present invention sequentially lays a neutralization slag isolation layer, a waste rock isolation layer, a vegetation growth layer and an ecological restoration protection layer on the surface of the acidic medium of the mine, and reasonably designs the composition of the raw materials of each layer to improve the vegetation coverage rate of ecological restoration, while reducing the generation of acidic water and the degree of wastewater pollution.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for ecological restoration using neutralization slag, characterized in that, It includes the following steps: S1. After uniformly mixing the qualified neutralization slag with the microbial inoculum and its nutrients, lay them on the surface of the acidic medium layer of the mine to form a neutralization slag isolation layer; the microbial inoculum is sulfate-reducing bacteria; S2. Uniformly lay the first waste rock with a predetermined particle size on the surface of the neutralization slag isolation layer to form a waste rock isolation layer; S3. Mix the qualified neutralization slag with flotation tailings, second waste rock, and soil to form a planting substrate, and uniformly mix the planting substrate with grass seeds and organic matter in a predetermined ratio, and then lay it on the surface of the waste rock isolation layer to form a vegetation growth layer; S4. Lay an ecological restoration protection layer on the surface of the vegetation growth layer; The qualified neutralization slag is as follows: the neutralization slag meets the requirements of Class I general industrial solid waste, and the liquid phase of the neutralization slag meets the discharge requirements, and the pH of the liquid phase of the neutralization slag is 8.5 - 9.0; When the neutralization slag does not meet the requirements, first perform pretreatment on the neutralization slag; The ways of the pretreatment include: Dissolve the neutralization slag with an acidic solution and make the pH value of the obtained neutralization slag turbid liquid be 2.8 - 3.

2. After fully stirring and reacting for 1.5 - 2.5 h, perform the first solid-liquid separation treatment to obtain the first solid slag and the first liquid; among them, the first solid slag is managed as hazardous waste; Adjust the pH value of the first liquid to between 8.5 - 9.0 with an alkaline substance. After fully reacting for 1.5 - 2.5 h, perform the second solid-liquid separation to obtain the second solid slag and the second liquid; the second solid slag is the neutralization slag that meets the requirements of Class I general industrial solid waste, and the second liquid is used for recycling the neutralization slag pretreatment or discharging up to standard.

2. The method for ecological restoration using neutralization slag according to claim 1, wherein: In step S1, the mass ratio of the qualified neutralization slag, microbial inoculum, and nutrients is 1 kg : 0.1 - 2 mg : 1 - 10 g.

3. The method for ecological restoration using neutralization slag according to claim 1, characterized in that: In step S1, the nutrients are one or a mixture of activated sludge of domestic sewage, straw, and feces.

4. The method for ecological restoration using neutralization slag according to claim 1, wherein: In step S1, the thickness of the neutralization slag isolation layer is 0.1 - 0.3 m.

5. The method for ecological restoration using neutralization slag according to claim 1, characterized in that: In step S2, the particle size of the first waste rock is 4 - 6 cm, and the thickness of the waste rock isolation layer is 0.05 - 0.15 m.

6. The method for ecological restoration using neutralization slag according to claim 1, characterized in that: In step S3, in the planting substrate, the mass ratio of the qualified neutralization slag, flotation tailings, second waste rock, and soil is: 100:10 - 50:10 - 50:10 - 50; the mass ratio of the planting substrate, grass seeds, and organic matter is 100:1 - 5:0.01 - 0.

1.

7. The method for ecological restoration using neutralization slag according to claim 1, characterized in that: In step S3, the particle size of the flotation tailings is 0.01 - 0.3 mm, and the particle size of the second waste rock is less than 1.5 cm; after the planting substrate is mixed with grass seeds and organic matter, mechanical stirring and screening are also carried out, and the screening particle size is less than 3 cm, and the undersize is used as mechanical spraying material for mechanical spraying.

8. The method for ecological restoration using neutralization slag according to claim 1, characterized in that: In step S4, the ecological restoration protection layer is non-woven fabric.

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