A mining method for resource utilization of abandoned mine based on silt solidification

Abstract

The application provides a kind of abandoned mine resource utilization mining method based on sludge solidification, and relates to the technical field of mining and resource recovery, comprising: sludge and water body composition analysis, layered extraction of water body, wastewater heavy metal treatment, multistage filtration and centrifugal separation, solidification body release and gradual slow release, multistage stirring, layered mining, waste rock and tailings backfilling.The application effectively realizes the environmental protection treatment and resource utilization of abandoned mine sludge, reduces environmental pollution, improves the recovery rate of mineral resources, and has good economic and social benefits.

Description

Technical Field

[0001] This invention relates to the field of mining and resource recovery technology, and in particular to a mining method for the resource utilization of abandoned mine pits based on silt solidification. Background Technology

[0002] As mining activities continue, the number of abandoned mine pits is increasing. These pits often accumulate large amounts of silt and water, creating an environmental burden and wasting resources. The silt in abandoned mine pits typically contains rich minerals, but due to its high water content and unstable structure, traditional dredging and resource recovery methods are insufficient for effectively extracting these minerals. Furthermore, the water in the silt easily leads to mud loss, resulting in low utilization rates of solidifying agents and minerals during solidification and mining processes, causing serious environmental problems and resource losses.

[0003] Current sludge treatment methods mainly focus on soil solidification and sludge dewatering, typically employing methods such as pumping, sedimentation, and landfill for initial treatment. However, these methods often lack systematic resource recovery mechanisms, especially for sludge containing valuable minerals, where traditional treatment methods cannot achieve resource recovery. Furthermore, uneven penetration and uncontrolled release of solidifying agents during the solidification process also affect treatment effectiveness, hindering the improvement of resource utilization rates in mine pits. In addition, wastewater treatment and water resource waste during the disposal of abandoned mine pits are also urgent environmental issues that need to be addressed.

[0004] Therefore, in response to the need for solidification and resource-based mining of abandoned mine sludge, there is an urgent need for a systematic and environmentally friendly treatment method to achieve layered solidification of sludge, layer-by-layer mining, and recycling of waste materials. This would not only improve the recycling efficiency of mineral resources but also effectively reduce the environmental impact of the treatment process, meeting the requirements of modern mining area environmental governance and sustainable resource development. Summary of the Invention

[0005] This invention provides a mining method for the resource utilization of abandoned mine pits based on sludge solidification, aiming to solve problems such as difficulty in recovering mineral resources, poor solidification effect, water waste, and environmental pollution in existing abandoned mine pit treatment processes. Through a systematic sludge treatment and layer-by-layer mining process, it achieves efficient utilization of mineral resources and environmentally friendly restoration of abandoned mine pits.

[0006] The present invention discloses a mining method for the resource utilization of abandoned mine pits based on sludge solidification, comprising the following steps:

[0007] S1. Sample and analyze the silt and water in the abandoned mine pit, determine the thickness of the silt layer and the accumulated water, and conduct mineral composition analysis.

[0008] S2. Extract water from the surface of the silt layer by layer, each extraction being carried out when the water body returns to a stable state after the previous pumping disturbance.

[0009] S3. Place the extracted water into a wastewater tank and add an adsorbent to remove heavy metals from the water; after sedimentation, once the heavy metal content in the wastewater meets the standard, discharge the upper layer of wastewater.

[0010] S4. Use a water pump equipped with a multi-stage filtration device to extract water from the sludge layer by layer, and use a moisture content sensor to monitor the moisture content of the sludge in real time.

[0011] S5. Add a solidifying agent to the silt layer;

[0012] S6. Use a multi-stage mixing device equipped with a drill bit to mix the silt layer;

[0013] S7. After the silt has completely solidified, use the top-down layered mining method to directly mine from the surface of the silt and collect the waste rock and tailings generated during the mining process.

[0014] S8 incorporates waste rock, tailings, cementing materials, and wastewater from the mining process into the mining pit.

[0015] Preferably, the adsorbent in S3 is at least selected from lime.

[0016] Preferably, step S4 further includes: the water pumped out by the pump is further centrifuged, the liquid phase after centrifugation enters the wastewater tank, and the solid phase is used for mineral recovery; the pump is selected from submersible sludge pumps and / or slurry pumps; the pump also has a filter screen according to the composition of the sludge; in this invention, the pump selects different specifications of filter screens according to the composition of the sludge, and combines centrifugation technology to remove water from the sludge to retain the solid components for mineral extraction; the water in the sludge is extracted layer by layer to a height of 4-5 meters, and the extraction of the next layer begins when the water content in the sludge is measured to be 65%-70% by the moisture content sensor.

[0017] Preferably, S5 further includes: the selection of the curing agent based on the mineral composition; the curing agent is processed into particles with a three-layer structure, with gelatin as the spacer between each layer, to ensure that the first layer is fully released on the first day, the second layer is released on the second to third day, and the third layer is released on the fourth to sixth day.

[0018] In this invention, the curing agent has a three-layer structure from the outside to the inside. The first layer is a fast-release layer, whose main purpose is to rapidly reduce the moisture content of the sludge, initiate the curing process, and simultaneously seal in heavy metal ions in the water. The components are calcium chloride (inorganic salt), bentonite (adsorbent), and aluminum sulfate (accelerator) (calcium chloride: 50-60 wt%, bentonite: 20-30 wt%, aluminum sulfate: 10-20 wt%). The second layer is a medium-release layer, which mainly enhances the curing effect through a more stable, slow-release curing agent, further stabilizes the sealed heavy metals, and enhances the mechanical strength of the solidified body. The components are cement (cementing material), calcium phosphate (for sealing heavy metals), and sodium silicate (waterproofing agent) (cement: 4%). 5-50wt%, calcium phosphate: 30-35wt%, sodium silicate: 15-20wt%); the third layer is a slow-release layer, mainly used for final reinforcement and long-term stable heavy metal sealing. The composition is volcanic ash and / or fly ash (to prolong the reaction time of the curing agent and provide a lasting reinforcement effect), sodium silicate (waterproofing agent) and calcium sulfate (slow-release hydrate) (volcanic ash: 40-50wt%, fly ash: 30-40wt%, sodium silicate: 5-10wt%, calcium sulfate: 5-10wt%).

[0019] The first layer releases rapidly, aiming to quickly absorb water and adsorb heavy metals, and rapidly accelerate the curing process. At this stage, the curing agent needs to have strong reactivity to quickly consume the water in the sludge and initiate the curing process.

[0020] The second layer releases more slowly, focusing on strengthening the structure and maintaining control over moisture and heavy metals. The curing process continues, but the release rate slows down to ensure the cured body gradually stabilizes.

[0021] The third layer gradually releases over a long period of time. This layer is responsible for long-term sealing, maintaining the overall stability of the solidified body, and preventing moisture and pollutants from penetrating back into the solidified layer, thus avoiding the re-release of heavy metals.

[0022] The amount of curing agent added should be 3%-5% of the sludge volume, depending on the moisture content.

[0023] The three-layer slow-release curing agent design ensures the gradual release of the curing agent into the sludge, resulting in a more uniform and effective curing process, and adapting to different curing requirements of the sludge. The curing process of sludge is gradual; releasing all the curing agent at once may lead to over-curing or an overly rapid reaction, negatively impacting the curing effect. The three-layer slow-release design ensures the continuous release of the curing agent at different stages, adapting to the curing needs at different stages and making the entire process more uniform. Furthermore, the slow release rate allows the chemical reaction between the curing agent and the sludge to proceed over a longer period, preventing localized over-reaction caused by early rapid release and enhancing the durability of the curing effect. By controlling the release rate of the curing agent, the three-layer slow-release design allows the curing process to be completed gradually according to the different parts and depths of the sludge, avoiding premature surface hardening while the interior remains incompletely cured. In addition, in some cases, releasing all the curing agent at once may lead to waste due to dilution by water or incomplete curing of some sludge. Through layered slow release, the curing agent can be released as needed, improving its utilization rate and avoiding unnecessary waste.

[0024] Preferably, S6 also includes: a drill bit at the front end of the mixing equipment, and a mixing stage is designed every 4 to 5 meters according to the thickness of the silt layer to form a multi-stage mixing structure; from top to bottom, the diameter of the mixing blades gradually decreases and the rotation speed of the mixing blades gradually increases.

[0025] Preferably, S7 also includes: using equipment with less disturbance, such as excavators, for excavating the upper layer of solidified sludge, and using equipment with greater disturbance, such as rock drilling and blasting, to complete the mineral excavation for excavating the lower layer of solidified sludge.

[0026] Preferably, the wastewater in S8 is selected from the wastewater discharged from the wastewater pond.

[0027] The beneficial effects of the technical solution provided by this invention include at least the following:

[0028] (1) Improve mineral resource recovery rate. This invention can effectively extract mineral components contained in sludge through systematic layering and solidification, avoiding the loss of mineral resources in traditional sludge treatment methods and greatly improving the mineral recovery rate.

[0029] (2) Improved curing effect and structural stability. This invention uses a specific curing agent and achieves uniform curing through multi-stage slow release and layered stirring. The multi-stage design of the stirring equipment ensures the uniform distribution of the curing agent at different layers, making the structure of the silt layer more stable after curing, which facilitates subsequent mining operations.

[0030] (3) Reduce environmental pollution and improve water resource utilization. This invention effectively removes heavy metals from water bodies through the use of heavy metal adsorbents and multi-stage wastewater treatment, ensuring that the discharged water meets environmental protection standards and reducing heavy metal pollution in mining areas. In addition, the wastewater generated during the treatment process, after the removal of heavy metals, can be reused for mixing cementitious materials and backfilling mining pits, realizing the recycling of water resources.

[0031] (4) Reduce energy and material costs for sludge treatment. By using layered pumping and multi-stage filtration, the moisture content of the sludge is reduced layer by layer, avoiding the need for high-temperature drying or excessive mechanical dehydration that consumes a lot of energy, thus significantly reducing treatment costs. At the same time, the curing agent is made from alternative materials such as volcanic ash and fly ash, further saving resources and improving the cost-effectiveness of the curing agent.

[0032] (5) Improve the safety and environmental friendliness of the mining process. The present invention adopts a layer-by-layer pumping and layered mining method, which effectively reduces the safety hazards caused by the instability of silt during the mining process. In addition, the waste rock and tailings generated during mining are mixed with cementing materials and wastewater and backfilled into the mining pit, which reduces the environmental impact caused by the transportation and accumulation of mining waste and ensures the ecological restoration of the mining area.

[0033] (6) Promote the sustainable development of mining areas. The systematic processing method of the present invention can not only effectively recover mineral resources, but also realize the resource utilization of mining waste and the ecological restoration of mining pits, which helps to build green mines and promote the sustainable development and environmental protection of mining areas. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart of the method of the present invention;

[0036] Figure 2 This is a contour map showing the thickness distribution of the silt layer in Example 1 of the present invention. Detailed Implementation

[0037] The technical solution of this invention is described below.

[0038] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0039] In this embodiment of the invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0040] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0041] This invention provides a mining method for the resource utilization of abandoned mine pits based on sludge solidification. Through systematic sludge treatment, stratified pumping, heavy metal removal, graded mining, and waste backfilling, it achieves stable solidification of sludge in abandoned mine pits and efficient recovery of mineral resources. The specific process is as follows: Figure 1 As shown, it includes the following steps:

[0042] S1. Compositional Analysis of Silt and Water. Silt and water samples were taken from the abandoned mine pit for analysis. Sonar technology was used to determine the thickness of the silt and water layers, and mineral composition analysis was performed. Particular attention was paid to the metallic mineral components in the silt and the heavy metal content in the water to provide data support for subsequent treatment processes.

[0043] This invention determines the basic conditions of water and silt in the mine pit through preliminary analysis of silt and water, and provides a basis for the selection of solidifying agents and adsorbents and the design of treatment processes.

[0044] S2 Layered water extraction. Water is extracted layer by layer from the surface of the silt. After each extraction, the water is allowed to settle and return to a stable state before the next extraction is performed, ensuring the stability of each layer of water and achieving the effect of layered water extraction.

[0045] The method of pumping water layer by layer in this invention can avoid the disturbance of the silt layer structure caused by large-scale pumping, maintain the stability of each layer of silt in the mine pit, and facilitate subsequent solidification and layered mining operations.

[0046] S3 Wastewater Heavy Metal Treatment. The extracted water is placed in a wastewater tank, and adsorbents such as lime are added to remove heavy metals. The adsorbents react with the heavy metal ions in the water to form insoluble precipitates, creating a sludge layer. After the wastewater has settled, the heavy metal content in the upper layer is measured. If it meets discharge standards, it is discharged. The precipitate can be stored for later use as filling material in the mine pit for further processing in step S8.

[0047] This invention ensures the environmentally friendly discharge of wastewater by adsorbing heavy metals, avoiding heavy metal pollution of the surrounding environment, while also reusing the precipitate as a resource, reducing the amount of waste to be treated.

[0048] S4 Multi-stage Filtration and Centrifugal Separation. Based on the particle size and moisture content of the sludge, a suitable filter screen is selected, and combined with centrifugal separation technology, water is extracted from the sludge layer by layer. The depth of each extraction is controlled at 4-5 meters, and the moisture content is monitored in real time. When the moisture content drops to 65%-70%, the next layer is extracted. The wastewater after centrifugal separation returns to the wastewater tank, and the separated solid minerals enter the mineral recovery process.

[0049] This invention utilizes multi-stage filtration and centrifugal separation to effectively reduce the moisture content of sludge while retaining mineral particles. This minimizes the interference of moisture on subsequent solidification and improves mineral resource recovery. Since directly draining the sludge is time-consuming and labor-intensive, and the solidification effect is poor and insufficient to support later mining, a scheme of initial dewatering followed by the use of a solidifying agent is chosen. Furthermore, considering factors such as saving electricity used for sludge extraction, the requirements for initial sludge dewatering, and facilitating subsequent solidifying agent mixing, a layered pumping design with a moisture content of 65%-70% is selected. Excessive water extraction can cause significant disturbance to the sludge, potentially leading to instability or over-dilution of the sludge layer. Controlling the pumping depth to 4-5 meters each time avoids excessively deep pumping at once, thus reducing the risk of sludge layer disturbance. This ensures a relatively smooth pumping process for each layer, guaranteeing the stability of the sludge layer. Maintaining a pumping depth of 4-5 meters each time also makes the operation more controllable. Compared to deep pumping, tiered pumping is easier to adjust during construction and can detect potential problems in a timely manner, avoiding unnecessary operational errors caused by excessive depth.

[0050] S5 Hardener Addition and Gradual Release. The hardener is added to the sludge layer. The composition of the hardener is selected based on the types of minerals in the sludge. If necessary, volcanic ash or fly ash can be added for resource utilization. The hardener adopts a three-layer structure design, with each layer separated by gelatin. The first layer is released completely within one day, the second layer is released on the second to third day, and the third layer is slowly released from the fourth to the sixth day.

[0051] The progressively slow-release design of the curing agent in this invention ensures the stability and durability of the curing process, enhances the curing effect, gradually increases the strength of the sludge layer, and avoids uneven curing or insufficient strength caused by rapid release of the curing agent. This invention uses a curing agent to transform liquid sludge into a robust and stable solid structure through a chemical reaction, facilitating subsequent mining processes, preventing mine collapse or breakage, and maintaining its curing effect over a long period to meet the requirements of long-term mining.

[0052] S6 Multi-stage mixing. A multi-stage mixing device equipped with a drill bit is used to mix the silt layer. The mixing stages are designed according to the thickness of the silt layer, typically one mixing stage every 4 to 5 meters. The mixing impeller is designed with a gradually decreasing blade diameter and a gradually increasing rotation speed from top to bottom, ensuring uniform distribution of the hardener at different depths and enhancing the mixing effect. The drill bit can be used to loosen the silt, allowing the hardener to fully penetrate.

[0053] The multi-stage mixing design of this invention ensures uniform distribution of the curing agent, preventing inconsistent curing effects at different depths, which could affect the layout of mining equipment. Furthermore, the superior multi-layer curing effect of multi-stage mixing directly benefits subsequent layered mining. The drill bit assists in breaking and loosening the silt structure, allowing the curing agent to penetrate deeper into the silt more easily, thus increasing the curing strength.

[0054] S7 Layered Mining. After the silt layer has completely solidified, a top-down layered mining method is adopted. For shallow layers, light equipment such as excavators are used to prevent excessive disturbance to the solidified layer; for deeper layers, drilling rigs or blasting are used to extract minerals. Waste rock and tailings generated during the mining process are collected for subsequent backfilling and resource utilization.

[0055] To avoid the collapse of the silt layer caused by dynamic disturbance, this invention adopts layered mining, which not only protects the stability of the ore body structure and ensures that the solidified layer is not damaged during the mining process, but also allows for the extraction of mineral resources from different layers in stages, further improving the resource recovery efficiency.

[0056] S8 Waste rock and tailings backfilling. Waste rock and tailings collected during mining are mixed with cementitious materials and treated wastewater to form a backfill material, which is then used to backfill the mining pit. This step utilizes waste materials to fill the mining pit, preventing tailings accumulation and further stabilizing the pit structure, thus achieving ecological restoration of the mining area.

[0057] This invention utilizes waste materials for backfilling, which on the one hand reduces the need for transporting solid waste, reduces environmental pollution, and realizes the internal circulation of solid waste in abandoned mine pits, and on the other hand restores the pits to a stable state, ensuring the safety of the mining area.

[0058] The following specific example will further illustrate the mining method for resource utilization of abandoned mine pits based on sludge solidification described in this invention.

[0059] Example 1

[0060] Taking a mine in the Democratic Republic of Congo as an example, development of this ore body began around the 1940s. By the 1960s-1980s, the shallow, high-grade oxide ore resources were largely exhausted, and open-pit mining ceased. However, based on existing exploration results, the estimated total resources are 1,955,455 tons, with 92,324 tons of copper (average grade 4.72%) and 5,550 tons of cobalt (average grade 0.28%), still possessing high mining value. Currently, the ore body's pit has become a waterlogged pond accumulated over many years, with a large amount of silt at the bottom. The presence of this water and silt severely hinders the development and utilization of deep resources. Regardless of whether open-pit or underground mining is employed, drainage and dredging of the pit are unavoidable issues. Drainage and dredging have become crucial prerequisites and key aspects for resuming mining operations at this mine.

[0061] Traditional dredging methods involve draining the water from the pit, mixing the silt at the bottom into a slurry, and pumping it out. However, this method has several problems, including but not limited to:

[0062] (1) Because the sludge discharged from the pumping pipeline is in a liquefied state and has mechanical properties similar to tailings, and the sludge contains minerals, it cannot be mixed with tailings. A separate storage site that meets the requirements of a tailings dam needs to be built, which is equivalent to building a new independent tailings dam.

[0063] (2) After the smelter expansion is completed, these stockpiled sludges need to be removed for use. The sludge that has been drained and solidified needs to be broken up, liquefied, and pumped again. The two dredging operations will incur huge unnecessary costs. According to incomplete estimates, at least US$10 million will be spent.

[0064] To address the aforementioned problems, this invention provides a mining method for the resource utilization of abandoned mine pits based on sludge solidification, which is applied to the dredging and mining work of such abandoned mines. The steps are as follows:

[0065] First, samples of silt and water from the abandoned mine pit were taken and analyzed. Sonar technology was then used to determine the thickness of the silt layer and the accumulated water, yielding the following results: Figure 2 The map shows the contour lines of the silt layer thickness distribution. The survey results indicate a water storage capacity of 3.444 million cubic meters, a silt volume of 1.955 million cubic meters, and a maximum depth exceeding 20 meters.

[0066] Based on the contour map of the silt layer thickness distribution, an extraction plan was determined. Three floating pump stations were used to extract water from the surface of the silt layer by layer, at intervals of 10 meters, with each extraction occurring every 24 to 48 hours. The extracted water was transported to a wastewater pond via rubber hoses. Lime was added to the wastewater pond to remove heavy metals from the water. Wastewater samples were taken periodically for chemical composition measurement. Once the heavy metal content in the wastewater reached the standard after sedimentation, the upper layer of wastewater was discharged.

[0067] Submersible muck pumps and horizontal slurry pumps are used in series. The submersible muck pump is placed in the silt and suspended using a hoisting device during dredging to ensure it is completely submerged at a depth of 4.5 to 5.0 meters underwater. The horizontal slurry pump acts as a relay pump to discharge the mixed slurry. The discharged solid-liquid mixture is centrifuged; the solid components are sent to the stope for metal refining, while the liquid components are discharged into a wastewater pond. A moisture content sensor is used to monitor the extraction process; when the moisture content reaches 65%-70%, extraction of the next layer begins.

[0068] After all silt layers have been treated, a solidifying agent is added to the silt layers. Since the moisture content is low at this stage, multi-layered slow-release volcanic ash and fly ash can be incorporated into the solidifying agent. Based on the silt contour map, a mixer equipped with a drill bit is used to drill into the bottom of the silt layer. Three mixing stages are designed, with the diameter of the mixing blades gradually decreasing and the rotation speed gradually increasing from top to bottom to fully mix the slurry and ensure uniform mixing.

[0069] After the silt has completely solidified, a top-down, layered mining method is used, extracting silt layer by layer from the surface. Excavators and other equipment with minimal disturbance are used when excavating the upper solidified silt; rock drilling and blasting equipment with greater disturbance are used when excavating the lower solidified silt to extract deeper minerals. During the mining process, waste rock and tailings are collected, and after mining is completed, cement and fly ash combined with wastewater are used to backfill the pit.

[0070] Statistics show that a mine in the Democratic Republic of Congo, by adopting this method, has cumulatively recovered 118 tons of minerals from its sludge, achieving a utilization rate of 84%, and generating cumulative revenue exceeding 8.4 million yuan. Furthermore, by eliminating the need for a sludge dump, indirect costs such as shortened construction time and reduced equipment expenses have been reduced by over 60 million yuan. In addition, the mine has cumulatively utilized over 200,000 tons of tailings, achieving solid waste recycling within the mine and obtaining significant economic benefits.

[0071] 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 technical scope 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 mining method for the resource utilization of abandoned mine pits based on sludge solidification, characterized by the following steps: include: S1. Sample and analyze the silt and water in the abandoned mine pit, determine the thickness of the silt layer and the accumulated water, and analyze the composition of the metallic minerals in the silt and the content of heavy metals in the water. S2. Extract water from the surface of the silt layer by layer, each extraction being carried out when the water body returns to a stable state after the previous pumping disturbance. S3. Place the extracted water into a wastewater tank and add an adsorbent to remove heavy metals from the water; after sedimentation, once the heavy metal content in the wastewater meets the standard, discharge the upper layer of wastewater. S4. Use a water pump equipped with a multi-stage filtration device to extract water from the sludge layer by layer, and use a moisture content sensor to monitor the moisture content of the sludge in real time. S5. Add a solidifying agent to the silt layer; the solidifying agent is selected based on its mineral composition; the solidifying agent is processed into granules with a three-layer structure, with each layer separated by gelatin, wherein the first layer is completely released on the first day, the second layer is released on the second to third day, and the third layer is released on the fourth to sixth day; the first layer of the solidifying agent consists of calcium chloride, bentonite, and aluminum sulfate; the second layer consists of cement, calcium phosphate, and sodium silicate; the third layer consists of volcanic ash and / or fly ash, sodium silicate, and calcium sulfate; S6. Use a multi-stage mixing device equipped with a drill bit to mix the silt layer; S7. After the silt has completely solidified, use the top-down layered mining method to directly mine from the surface of the silt and collect the waste rock and tailings generated during the mining process. S8 fills the mining pit with waste rock, tailings, cementing materials, and wastewater generated during the mining process.

2. The method according to claim 1, characterized in that, The adsorbent in S3 is at least selected from lime.

3. The method according to claim 1, characterized in that, S4 also includes: the water pumped out by the water pump is further separated by centrifugation, the liquid phase after centrifugation enters the wastewater pool, and the solid phase is used for mineral recovery.

4. The method according to claim 1, characterized in that, In S5, the curing agent is added at 3wt%-5wt% of the sludge volume.

5. The method according to claim 1, characterized in that, The S6 also includes: a drill bit at the front end of the mixing equipment, and a mixing stage designed every 4 to 5 meters according to the thickness of the silt layer, forming a multi-stage mixing structure; from top to bottom, the diameter of the mixing blades gradually decreases and the rotation speed of the mixing blades gradually increases.

6. The method according to claim 1, characterized in that, S7 also includes: using equipment with less disturbance, such as excavators, for excavating the upper layer of solidified sludge, and using equipment with greater disturbance, such as rock drilling and blasting, for excavating the lower layer of solidified sludge.

7. The method according to claim 1, characterized in that, In S8, the wastewater is selected from the wastewater discharged from the wastewater pond.

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