A method for source control of acidic wastewater in mine tunnels

Abstract

The present invention relates to a method for controlling acidic wastewater at the source in a mine tunnel. Through experimental research on specific covering layer materials, the specific materials for setting up the covering layer are determined, and the covering method is used to cover the area around the mine tunnel, thereby controlling the formation of acidic wastewater at the source, greatly enhancing the treatment effect, and reducing the treatment cost. At the same time, for the already formed acidic wastewater, adding lime ore in the mine tunnel is used to neutralize the existing acidic wastewater and conduct numerical simulation on the mine tunnel area to obtain the distribution of the seepage layer in the area around the mine tunnel, and anti-seepage materials are laid above the seepage layer in the formation, so as to achieve the effect of improving the treatment effect of acidic wastewater in the mine tunnel.

Description

Technical Field

[0001] The present invention relates to the field of pollution control, and particularly to a method for controlling the source of acidic wastewater in mine tunnels. Background Art

[0002] Acidic wastewater in mine tunnels is the product of physical and chemical reactions of metal ore deposits and sulfur-containing ore bodies. It is a worldwide issue that is widespread, difficult to treat, and has a serious environmental impact. Mine tunnels can continuously produce acidic wastewater with a low pH value, high concentrations of heavy metal ions, and other toxic non-metallic elements, posing a serious threat to the ecological environment and affecting the health and safety of local residents. It is urgent to vigorously promote the ecological protection of mining areas, increase the intensity of environmental protection and restoration of mines, and focus on promoting the restoration and treatment of abandoned mines and historical mine tunnels.

[0003] Currently, the treatment of mine acidic wastewater mainly focuses on the back-end treatment. By treating the already formed acidic wastewater, the acidity of the wastewater is changed, and the metal ions in the wastewater are precipitated, thereby reducing the pollution to the environment, soil, and water system. However, although the above method can restore the polluted environment, soil, and water system, the cost spent in the treatment process is very high, and the operation is also relatively complex, with great difficulty. Therefore, the treatment effect is not good. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for the source of acidic wastewater in mine tunnels in view of the deficiencies of the above technical solutions. By setting the specific materials of the covering layer and using the covering method to cover the surrounding area of the mine tunnel, the formation of acidic wastewater is controlled. At the same time, for the already formed acidic wastewater, lime ore is added to the mine tunnel to neutralize the existing acidic wastewater and perform numerical simulation on the mine tunnel area to obtain the distribution of the water seepage layer in the surrounding area of the mine tunnel, and an anti-seepage material is laid above the water seepage layer in the formation, thereby achieving the effect of improving the treatment effect of acidic wastewater in mine tunnels.

[0005] First, the concepts involved in the present application will be described in conjunction with the accompanying drawings. It should be noted here that the following descriptions of each concept are only for making the content of the present application easier to understand and do not represent a limitation on the protection scope of the present application.

[0006] To achieve the above object, a method for controlling the source of acidic wastewater in mine tunnels is provided, including the following steps:

[0007] Step 1: Selection of covering layer materials for the surrounding area of the mine tunnel;

[0008] Step 2: Determine the covering layer materials;

[0009] Step 3: Cover the surrounding area of the mine tunnel with the covering layer materials determined in Step 2;

[0010] Step 4: Treat the acidic wastewater.

[0011] Specifically, different covering materials can be selected according to the characteristics of the area where the mine tunnel is located; the covering layer can be made of one or several of the materials such as water, organic matter, activated sludge, coal ash, etc.

[0012] Furthermore, the organic matter is specifically tree residues such as tree branches and leaves;

[0013] Furthermore, the activated sludge is a product in the sewage treatment process of a sewage treatment plant. Activated sludge is a solid waste with a wide range of sources. On the other hand, a large amount of microorganisms are contained in the activated sludge. By adding activated sludge to the covering layer, the contact probability between the ore and oxygen in the air can be reduced, and the microorganisms in the activated sludge will also consume part of the oxygen when the air passes through, further reducing the amount of oxygen in contact with the ore;

[0014] Even further, the coal ash is fly ash formed after coal combustion, which is an industrial waste with the characteristics of large discharge and wide distribution. Due to its large specific surface area, high surface activation performance, and containing many active substances such as aluminides and silicides, the coal ash has a certain adsorption effect on the precious metal ions in the acidic wastewater of the mine tunnel. In addition to adsorbing the precious metal ions in the acidic wastewater of the mine tunnel, some components in the coal ash can also react with the harmful substances in the acidic wastewater of the mine tunnel. And when the acidic wastewater of the mine tunnel penetrates through the coal ash, the suspended solids in the acidic wastewater of the mine tunnel can be removed;

[0015] Preferably, the material of the covering layer is composed of coal ash and activated sludge.

[0016] The covering layer material is prepared by using a mixture of activated sludge and fly ash. A large amount of bacteria and other microorganisms are contained in the activated sludge, which can consume the oxygen in water, air, etc. passing through the covering layer and reduce the probability of oxygen contacting the tailings. The composition of coal ash contains alkaline substances such as calcium oxide, which can neutralize part of the generated acidic substances. Coal ash is composed of a large number of particles with a porous structure and has a certain adsorption property, which can remove some heavy metal ions in the passing wastewater;

[0017] Specifically, the said Step 2 specifically includes:

[0018] Step 2.1: Mix the activated sludge and coal ash in different proportions respectively to obtain four different covering layer materials;

[0019] Specifically, mix them in the volume ratios of 1:1, 1:1.5, 1:2, and 1:3;

[0020] Step 2.2: Obtain the particle size, water content, and water seepage index of the four covering layer materials;

[0021] Specifically, the granularity index is obtained by the observation method;

[0022] Furthermore, the granularity is divided into three types: fine particles, relatively uniform particles, and coarse particles;

[0023] Specifically, the water content is obtained by the experimental method. Take 100 g of each of the four covering materials, encapsulate them in different air-drying boxes, dry them with an air dryer, and finally weigh them. Measure the water content according to the weight after air-drying. Substantially, the water content will affect the activity of microorganisms in the activated sludge. If the water content is too low, it may cause the death of microorganisms.

[0024] Specifically, the water seepage index is obtained by the experimental method. Take one portion of the mixture of the four covering materials with a volume of 500 ml beaker size and place it in a column with holes at the bottom. Place a beaker under the column to receive the water. Add 200 ml of water to each mixture. After 1 hour, compare the amount of water seeping down in the beaker at the bottom, and determine the water seepage index by the amount of water seepage.

[0025] Step 2.3: Select a suitable covering material according to the three indexes obtained in Step 2.2;

[0026] Specifically, the covering material should contain more aerobic bacteria to eliminate the oxygen in the permeating air. In order to maintain the growth of microorganisms, a higher proportion of water content should be selected; considering the protective effect of the covering layer on the surrounding area of the mine tunnel and reducing the amount of surface runoff infiltrating into the mine tunnel, a lower proportion of water seepage index should be selected; coal ash contains alkaline substances, which can neutralize some of the generated acidic substances. Therefore, the content of coal ash in the covering layer cannot be too low. Therefore, the covering material is selected by mixing activated sludge and fly ash according to a volume ratio of 1:1.5.

[0027] Regarding the harm of the mine tunnel to the environment, in this embodiment, the covering method is used to conduct experimental research on source control, analyze the mechanism of acid wastewater generation, and cover the ore samples with a mixture of activated sludge and fly ash. On the one hand, it reduces the contact between the ore samples and the oxygen in the air, thereby reducing the probability of oxidation of sulfide ores in the ore. On the other hand, it reduces the infiltration rate of surface runoff water into the ore samples, controls it before the generation of acid wastewater, and fundamentally reduces the generation of mine acid wastewater.

[0028] Specifically, Step 4 specifically includes:

[0029] Step 4.1: Add a certain amount of lime ore in the mine tunnel to neutralize the existing acid wastewater;

[0030] Specifically, lime ore contains abundant alkaline substances and is relatively easy to obtain. Therefore, putting lime ore into the acidic wastewater can increase the pH value of the acidic wastewater;

[0031] Step 4.2: Conduct numerical simulation on the mine tunnel area to obtain the distribution of the water infiltration layer in the area around the mine tunnel;

[0032] By using the numerical simulation method to obtain the distribution of the water infiltration layer in the area around the mine tunnel, if the entire area around the mine tunnel is treated, on the one hand, the area is large and there is a situation of resource waste. On the other hand, treating the non-water infiltration layer does not play a major role in the treatment of the entire acidic wastewater. Therefore, in this embodiment, a method of numerical simulation is set up to obtain the distribution of the water infiltration layer in the area around the mine tunnel;

[0033] Step 4.3: According to the distribution of the water infiltration layer obtained in Step 4.2, lay anti-seepage materials above the water infiltration layer in the formation;

[0034] Specifically, through Step 4.3, laying anti-seepage materials on the water infiltration layer in the formation can control the amount of rainwater infiltration, thereby reducing the inflow of water into the mine tunnel, and thus controlling the formation of part of the acidic wastewater.

[0035] Furthermore, Step 4.2 is specifically to obtain the distribution of the water infiltration layer in the area around the mine tunnel by establishing a numerical simulation model;

[0036] Furthermore, Step 4.2 specifically includes:

[0037] By establishing a three-dimensional heterogeneous mathematical model for mathematical representation of each formation:

[0038]

[0039] D(x, y, z, 0) = D0(x, y, z) (x, y, z) ∈ Ω

[0040]

[0041] In the formula, Ω is the calculation domain, D is the water layer height, D0 is the initial water layer height, S xx 、S yy 、S zz 、S n are the numerical components of the permeability coefficient S on the coordinate axes x, y, x, and the normal direction n, Z x is the water storage rate of the infiltration layer, Γ2 is the boundary of the water flow, q(x, y, z, t) is the flow rate at the coordinate (x, y, z) at time t, L is the initial flow rate, H is the thickness of the water infiltration layer, and t is the time.

[0042] The distribution of the water seepage layer is predicted and solved through the above three-dimensional heterogeneous mathematical model, so as to obtain the distribution of the water seepage layer in the area around the mine tunnel.

[0043] Furthermore, the present invention also includes a computer-readable storage medium, on which a data processing program is stored, and the data processing program is executed by a processor to implement the above method for controlling the source of acidic wastewater in the mine tunnel.

[0044] Based on the above technical solutions, a method for evaluating the environmental pollution risk of mining waste residue provided by the present application has the following technical effects:

[0045] 1. Through experimental research on specific covering layer materials, the present invention determines the specific materials of the covering layer and uses the covering method to cover the area around the mine tunnel, thereby controlling the formation of acidic wastewater at the source, greatly enhancing the treatment effect, and reducing the treatment cost.

[0046] 2. For the already formed acidic wastewater, lime ore is added in the mine tunnel to neutralize the existing acidic wastewater and numerically simulate the mine tunnel area to obtain the distribution of the water seepage layer in the area around the mine tunnel. An anti-seepage material is laid above the water seepage layer in the formation, thereby achieving the effect of improving the treatment effect of acidic wastewater in the mine tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings forming a part of this specification are used to provide a further understanding of this specification. The schematic embodiments and descriptions thereof in this specification are used to explain this specification and do not constitute an improper limitation to this specification. In the drawings:

[0048] Figure 1 is a flowchart of a method for controlling the source of acidic wastewater in a mine tunnel provided by an embodiment of the present application;

[0049] Figure 2 is a flowchart for determining the covering layer material provided by an embodiment of the present application;

[0050] Figure 3 is a flowchart for treating acidic wastewater provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] To make the objectives, technical solutions, and advantages of the embodiments of this specification clearer, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are some, but not all, of the embodiments of this specification. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this specification without making creative efforts shall fall within the scope of protection of this specification. It should be noted that, without conflict, the embodiments in this specification and the features in the embodiments can be combined with each other arbitrarily.

[0052] Unless the context clearly requires otherwise, the words such as "including" and "comprising" in the entire specification and claims shall be construed in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to".

[0053] Example 1

[0054] As Figure 1 shown, a method for source control of acidic wastewater in mine tunnels includes the following steps:

[0055] Step 1: Selection of covering layer materials in the area around the mine tunnel;

[0056] Specifically, different covering materials can be selected according to the characteristics of the area where the mine tunnel is located; the covering layer can adopt one or several of materials such as water, organic matter, activated sludge, coal ash, etc.

[0057] Furthermore, the organic matter is specifically tree residues such as tree branches and leaves;

[0058] Furthermore, the activated sludge is a product in the sewage treatment process of a sewage treatment plant. Activated sludge is a solid waste with a wide source. On the other hand, a large number of microorganisms are contained in the activated sludge. By adding activated sludge to the covering layer, the contact probability between the ore and oxygen in the air can be reduced, and the microorganisms in the activated sludge will also consume part of the oxygen in the air when the air passes through, further reducing the amount of oxygen in contact with the ore;

[0059] Even further, the coal ash is fly ash formed after coal combustion, which is an industrial waste with the characteristics of large discharge and wide distribution. Due to its large specific surface area, high surface activation performance, and containing many active substances such as aluminides and silicides, the coal ash has a certain adsorption effect on precious metal ions in the acidic wastewater of the mine tunnel. In addition to adsorbing precious metal ions in the acidic wastewater of the mine tunnel, some components in the coal ash can also react with harmful substances in the acidic wastewater of the mine tunnel. And when the acidic wastewater of the mine tunnel penetrates through the coal ash, the suspended solids in the acidic wastewater of the mine tunnel can be removed;

[0060] Preferably, the material of the covering layer is composed of coal ash and activated sludge.

[0061] Step 2: Determine the covering layer materials;

[0062] The covering layer material is prepared by using a mixture of activated sludge and fly ash. The activated sludge contains a large number of microorganisms such as bacteria, which can consume the oxygen in water, air, etc. passing through the covering layer, reducing the chance of oxygen contacting the tailings. The composition of fly ash contains alkaline substances such as calcium oxide, which can neutralize some of the generated acidic substances. Fly ash is composed of a large number of particles with a porous structure and has a certain adsorbability, which can remove some heavy metal ions in the passing wastewater;

[0063] Specifically, as Figure 2 shown, step 2 specifically includes:

[0064] Step 2.1: Mix the activated sludge and fly ash in different proportions respectively to obtain four different covering layer materials;

[0065] Specifically, mix them in the volume ratios of 1:1, 1:1.5, 1:2, and 1:3;

[0066] Step 2.2: Obtain the particle size, water content, and water infiltration index of the four covering layer materials;

[0067] Specifically, the particle size index is obtained by the observation method;

[0068] Furthermore, the particle size is divided into three types: fine particles, relatively uniform particles, and coarse particles;

[0069] Specifically, the water content is obtained by the experimental method. Take 100 g of each of the four covering layer materials, encapsulate them in different air-drying boxes, and air-dry them through an air-dryer. Finally, weigh them, and measure the water content according to the weight after air-drying. Substantially, the water content will affect the activity of microorganisms in the activated sludge. If the water content is too low, it may cause the death of microorganisms.

[0070] Specifically, the water infiltration index is obtained by the experimental method. Take one portion of the mixture of each of the four covering layer materials with a volume of 500 ml beaker size and place it in a column with holes at the bottom. Use a beaker to receive the water under the column. Add 200 ml of water to each mixture. After 1 hour, compare the amount of water that seeps down into the beaker at the bottom, and determine the water infiltration index based on the amount of water infiltration.

[0071] Exemplarily, the comparison of the four covering layer materials with different volume ratios is as follows:

[0072] 1：1 1:1.5 1:2 1:3 Particle size Fine particles Relatively uniform particles Coarse particles Coarse particles Water content 69％ 57％ 46％ 31％ Water seepage index 22％ 36％ 54％ 78％

[0073] Step 2.3: Select a suitable covering layer material according to the three indexes obtained in step 2.2;

[0074] Specifically, the covering layer material should contain a relatively large number of aerobic bacteria to eliminate the oxygen in the permeating air. In order to maintain the growth of microorganisms, a relatively high water content ratio should be selected. Considering the protective effect of the covering layer on the area around the mine tunnel and reducing the amount of surface runoff infiltrating into the mine tunnel, a relatively low water seepage index ratio is selected. Coal ash contains alkaline substances that can neutralize some of the generated acidic substances. Therefore, the content of coal ash in the covering layer cannot be too low. Therefore, the covering layer material is selected by mixing activated sludge and fly ash in a volume ratio of 1:1.5.

[0075] Step 3: Cover the area around the mine tunnel with the covering layer material determined in Step 2.

[0076] Regarding the harm of the mine tunnel to the environment, in this embodiment, the covering method is used to conduct source control experimental research, analyze the mechanism of the generation of acidic wastewater, and cover the ore sample with a mixture of activated sludge and fly ash. On the one hand, it reduces the contact between the ore sample and the oxygen in the air, thereby reducing the probability of oxidation of sulfide ores in the ore. On the other hand, it reduces the rate of surface runoff water infiltrating into the ore sample, and controls it before the generation of acidic wastewater, fundamentally reducing the generation of mine acidic wastewater.

[0077] Step 4: Treat the acidic wastewater.

[0078] Specifically, as Figure 3 shown, Step 4 specifically includes:

[0079] Step 4.1: Add a certain amount of limestone ore into the mine tunnel to neutralize the existing acidic wastewater.

[0080] Specifically, limestone ore contains rich alkaline substances and is relatively easy to obtain. Therefore, putting limestone ore into the acidic wastewater can increase the pH value of the acidic wastewater.

[0081] Step 4.2: Conduct numerical simulation on the mine tunnel area to obtain the distribution of the water seepage layer in the area around the mine tunnel.

[0082] By using the numerical simulation method to obtain the distribution of the water seepage layer in the area around the mine tunnel, if the entire area around the mine tunnel is treated, on the one hand, the area is large and there is a situation of resource waste. On the other hand, treating the non-water seepage layer does not play a significant role in the treatment of the entire acidic wastewater. Therefore, in this embodiment, a method of numerical simulation is set up to obtain the distribution of the water seepage layer in the area around the mine tunnel.

[0083] Step 4.3: According to the distribution of the water seepage layer obtained in Step 4.2, lay anti-water seepage materials on the water seepage layer in the formation.

[0084] Specifically, through step 4.3, anti-seepage materials are laid above the water seepage layer in the formation, which can control the amount of rainwater infiltration, thereby reducing the inflow of water into the mine tunnel and thus controlling the formation of some acidic wastewater.

[0085] Embodiment 2:

[0086] This embodiment is generally the same as Embodiment 1, and the main difference lies in step 4.2:

[0087] Specifically, step 4.2 is to obtain the distribution of the water seepage layer in the area around the mine tunnel by establishing a numerical simulation model;

[0088] Furthermore, step 4.2 specifically includes:

[0089] Establish a three-dimensional heterogeneous mathematical model for mathematical representation of each formation:

[0090]

[0091] D(x, y, z, 0) = D0(x, y, z) (x, y, z) ∈ Ω

[0092]

[0093] In the formula, Ω is the calculation domain, D is the water layer height, D0 is the initial water layer height, S xx 、S yy 、S zz 、S n are the numerical components of the permeability coefficient S on the coordinate axes x, y, x, and the normal direction n, Z x is the water storage rate of the permeable layer, Γ2 is the boundary of the water flow, q(x, y, z, t) is the flow rate at the coordinate (x, y, z) at time t, L is the initial flow rate, H is the thickness of the water seepage layer, and t is the time.

[0094] Predict and solve the distribution of the water seepage layer through the above three-dimensional heterogeneous mathematical model, so as to obtain the distribution of the water seepage layer in the area around the mine tunnel.

[0095] Embodiment 3

[0096] This embodiment includes a computer-readable storage medium, on which a data processing program is stored, and the data processing program is executed by a processor to implement the method for controlling the source of acidic wastewater in the mine tunnel of Embodiment 1 or Embodiment 2.

[0097] Although the preferred embodiments herein have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of this article.

[0098] Obviously, those skilled in the art can make various changes and modifications to this text without departing from the spirit and scope of this text. Thus, if these modifications and variations of this text fall within the scope of the claims of this text and their equivalent technologies, then the intention of this text also includes these modifications and variations.

Claims

1. A method for controlling acid mine drainage at the source, characterized in that: It includes the following steps: Step 1: Selection of covering layer materials for the area around the mine tunnel; Step 2: Determine the covering layer materials; The determination of the covering layer materials in Step 2 specifically includes: Step 2.1: Mix activated sludge and coal ash in different proportions respectively to obtain four different covering layer materials; specifically, mix them in the volume ratios of 1:1, 1:1.5, 1:2, and 1:3; Step 2.2: Obtain the particle size, water content, and water seepage index of the four covering layer materials; Step 2.3: Select suitable covering layer materials according to the three indicators obtained in Step 2.2; Step 3: Cover the area around the mine tunnel with the covering layer materials determined in Step 2; Step 4: Treat the acidic wastewater; The treatment of the acidic wastewater in Step 4 specifically includes: Step 4.1: Add a certain amount of lime ore into the mine tunnel to neutralize the existing acidic wastewater; Step 4.2: Conduct numerical simulation on the mine tunnel area to obtain the distribution of the water seepage layer around the mine tunnel; Step 4.3: Lay anti-seepage materials above the water seepage layer in the stratum according to the water seepage layer distribution obtained in Step 4.

2.

2. The method for controlling acidic wastewater at the source in mine tunnels according to claim 1, wherein The water content is obtained through the experimental method. Take 100 g of each of the four covering layer materials, encapsulate them in different air-drying boxes, and air-dry them through an air-dryer. Finally, weigh them, and measure the water content according to the weight after air-drying. Substantially, the water content will affect the activity of microorganisms in the activated sludge. If the water content is too low, it may cause the death of microorganisms; the water seepage index is obtained through the experimental method. Take one portion of the mixture of each of the four covering layer materials with a volume of 500 mL beaker size, place it in a column with holes at the bottom, and receive it with a beaker under the column. Add 200 mL of water to each mixture. After 1 hour, compare the amount of water seeping down in the bottom beaker, and determine the water seepage index through the amount of water seepage.

3. The source control method for acidic wastewater in mine tunnels according to claim 1, characterized in that, Adopt the covering method to conduct experimental research on source control, analyze the mechanism of acidic wastewater generation, and cover the ore sample with a mixture of activated sludge and coal ash.

4. A computer-readable storage medium, on which a data processing program is stored, and the data processing program is executed by a processor to implement the method for source control of acidic wastewater in a mine tunnel according to any one of claims 1-3.

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