A stabilizer for controlling heavy metal pollution in lead-zinc mine tailings and its application method

Abstract

The present application relates to the control of lead-zinc mine tailings heavy metal pollution stabilizer and its application method, the stabilizer includes basic component A and reinforcing component B;Wherein basic component A is polyaluminum chloride iron 35%~50%, polyferric sulfate 10%~12%, calcium hydroxide 20%~50%, calcium carbonate 10%~30%, iron oxide 0.1%~2.0%;Reinforcing component B is sodium silicate.Polyaluminum chloride iron, polyferric sulfate, calcium hydroxide, calcium carbonate, iron oxide are mixed uniformly, activated, namely the basic component A;Reinforcing component B is used into the concentration 0.1~3.0% aqueous solution.The raw material of the present application is rich, low cost, high efficiency environmental protection, can realize the solidification stabilization to the heavy metal pollutants in lead-zinc mine tailings, significantly reduces the leaching of heavy metals in tailings.

Description

Technical Field

[0001] This invention relates to the field of tailings management technology, and more specifically to a stabilizer for controlling heavy metal pollution in lead-zinc mine tailings and its application method. Background Technology

[0002] Lead-zinc ore typically contains various metal sulfide minerals such as galena (PbS), sphalerite (ZnS), pyrite (FeS2), and arsenopyrite (FeAsS), as well as small amounts of water-soluble heavy metal sulfates and sulfites derived from the oxidation of sulfide minerals. Due to the complexity of geological mineralization conditions and changes in the geological environment, various metal minerals are inter-embedded. Some metals, such as cadmium, enter the crystal lattice of other metal minerals in an isomorphous manner; at the same time, some metal minerals are also embedded in gangue (non-metallic minerals) in extremely fine micron-sized disseminated forms, making it difficult to separate and recover the various minerals. After beneficiation, the tailings inevitably contain various metal minerals (galena and sphalerite containing lead and zinc, sphalerite containing cadmium, pyrite and arsenopyrite containing arsenic and sulfur, etc.). Therefore, lead-zinc ore tailings usually contain water-soluble heavy metals and water-insoluble but oxidizable heavy metal sulfide minerals. The presence of pollutants such as cadmium, lead, arsenic, zinc, and sulfur limits the industrial utilization of lead-zinc mine tailings. However, lead-zinc mine tailings disposed of in natural environments through tailings ponds, dry heaps, and other storage methods can also lead to the oxidation of metal minerals due to the combined effects of water and oxygen, especially acid rain erosion. This results in the formation of various water-soluble substances such as heavy metal sulfates. At the same time, the oxidation of metal sulfides such as pyrite (FeS2), arsenopyrite (FeAsS), galena, and sphalerite in the tailings can also produce acidic substances, further acidifying the microenvironment in the tailings and exacerbating the leaching of heavy metals. It can be seen that after being soaked in water, heavy metals in lead-zinc mine tailings will be transferred to the aqueous phase, and the concentration can exceed the limits of the "Integrated Wastewater Discharge Standard" (GB8978-1996). They are usually classified as Class II solid waste, causing serious heavy metal pollution to the ecological environment.

[0003] For a long time, lead-zinc mining has resulted in the generation of large amounts of tailings containing heavy metal pollutants. The accumulation of tailings has a significant impact on or damages the local ecological environment, especially soil, groundwater, and surface water resources, and can even cause serious pollution. Controlling heavy metal pollution in lead-zinc mine tailings and achieving the harmless disposal of lead-zinc mine tailings containing multiple metal pollutants such as cadmium, lead, arsenic, and zinc has become an urgent need to solve the major environmental and social problems facing the lead-zinc mining and beneficiation industry. Chinese patent document publication number CN106747249B discloses a stabilizing agent for lead-zinc waste rock tailings and its preparation and application. This stabilizing agent has a complex composition, lacks leaching data before stabilization in the published document, and only provides removal rate without concentration indicators, so the stabilization effect may not consistently meet the standards. Chinese patent publication number CN114276055B discloses a heavy metal solidification stabilizer for tailings treatment and its application. This heavy metal solidification stabilizer is composed of active silica solid waste and calcium-rich solid waste, used at a weight ratio of heavy metal solidification stabilizer to tailings of 1:1 to 1:3. However, this method involves excessive use of the heavy metal solidification stabilizer, resulting in significant tailings volume increase and difficulties in subsequent tailings disposal. Chinese patent publication number CN113399451B discloses a method for solidifying and repairing lead-zinc tailings. This method involves layering the lead-zinc tailings for solidification, injecting microbial inoculum and cementing solution into each layer, followed by standing and drying. The standing time is 2 days, the drying temperature is 100-110℃, and the drying time is 24-36 hours. This method suffers from technical complexity and operational difficulties. Summary of the Invention

[0004] The technical problem this invention aims to solve is to provide a stabilizer for controlling heavy metal pollution in lead-zinc mine tailings and its application method, which can harmlessly dispose of lead-zinc mine tailings containing heavy metals such as cadmium, lead, arsenic, and zinc. This patent can solidify and stabilize heavy metal pollutants in lead-zinc mine tailings, reducing or eliminating the pollution hazards and potential risks of lead-zinc mine tailings, and transforming a high-pollution industry into a green and low-pollution industry.

[0005] To solve this technical problem, the present invention adopts the following technical solution:

[0006] A stabilizer for controlling heavy metal pollution in lead-zinc mine tailings, comprising: a base component A and a reinforcing component B;

[0007] The basic component A includes polyaluminum ferric chloride, polyferric sulfate, calcium hydroxide, calcium carbonate, and iron oxide;

[0008] The polyaluminum ferric chloride is an industrial-grade product, with the main components being alumina ≥26%, ferric oxide 3%–6%, basicity ≥65%, and arsenic ≤0.0003%.

[0009] The calcium hydroxide, polyferric sulfate, calcium carbonate, and iron oxide mentioned are all industrial-grade products;

[0010] Preferably, calcium hydroxide, polyferric sulfate, calcium carbonate, and iron oxide are analytical grade products.

[0011] Based on a total mass of 100%, the basic component A comprises: 35%–50% polyaluminum ferric chloride, 10%–12% polyferric sulfate, 20%–50% calcium hydroxide, 10%–30% calcium carbonate, and 0.1%–2.0% iron oxide; preferably, the basic component A comprises: 37 kg of polyaluminum ferric chloride, 11 kg of polyferric sulfate, 48 kg of calcium hydroxide, 3.0 kg of calcium carbonate, and 1.0 kg of iron oxide;

[0012] The reinforcing component B is 0.3% sodium silicate.

[0013] The preparation method of the basic component A involves mixing polyaluminum ferric chloride, polyferric sulfate, calcium hydroxide, calcium carbonate, and iron oxide powder in a certain proportion.

[0014] Preferably, the preparation method of the basic component A involves mixing polyaluminum ferric chloride, polyferric sulfate calcium hydroxide, calcium carbonate, and iron oxide in a certain proportion and then mechanically activating them.

[0015] The mechanical activation refers to grinding a mixture of polyaluminum ferric chloride, polyferric sulfate, calcium hydroxide, calcium carbonate, and iron oxide powder in a grinding device.

[0016] The grinding equipment mentioned refers to ball mills, Raymond mills, etc.;

[0017] Preferably, the material is ground to ≤200 mesh;

[0018] The reinforcing component B is: industrial-grade sodium silicate;

[0019] Preferably, the reinforcing component B is: analytical grade sodium silicate;

[0020] The present invention also provides a method for applying the stabilizer for controlling heavy metal pollution in lead-zinc mine tailings. Preferably, the lead-zinc mine tailings contain at least one of the heavy metals cadmium, lead, arsenic, and zinc, wherein the arsenic content in the tailings is ≤5000 mg / kg, the lead content is ≤5000 mg / kg, and the zinc content is ≤5000 mg / kg.

[0021] This invention also provides a method for controlling heavy metal pollution in lead-zinc mine tailings, comprising the following steps:

[0022] Step 1: Mix the basic component A with lead-zinc ore tailings at a mass ratio of 0.5% to 3%;

[0023] Step 2: Prepare an aqueous solution of reinforcing component B with a concentration of 0.1-3.0% and add it to the lead-zinc ore tailings that have been mixed in Step 1. At the same time, add water to form a solidified and stabilized body with a water content of 15%-40%.

[0024] Step 3: Stack the solidified and stabilized body obtained in Step 2 to form a solidified body of lead-zinc ore tailings;

[0025] Step 4: The solidified body is cured to complete the solidification and stabilization of heavy metal pollution in lead-zinc mine tailings.

[0026] Preferably, the pH of the cured stabilized body in step two is controlled at 7.5 to 9 by controlling the amount of basic component A in step one;

[0027] Preferably, in step four, the curing time is 48 hours.

[0028] Beneficial effects

[0029] The main advantages of this invention compared to existing technologies are:

[0030] Lead-zinc mine tailings typically have a particle size of around 200 mesh. Heavy metals such as arsenic, cadmium, lead, and zinc in the tailings exist in two phases based on their solubility: one is water-soluble, consisting of one or more of these heavy metals; the other is water-insoluble, consisting of sulfide minerals or oxides containing these heavy metals. The latter type of sulfide minerals, in the presence of water and oxygen, is easily oxidized to form water-soluble substances, acidifying the tailings microenvironment and further dissolving heavy metal oxides. These are the main reasons for heavy metal pollution from lead-zinc mine tailings. This invention can control heavy metal pollution from tailings from multiple dimensions. The polyaluminum ferric chloride, polyferric sulfate, calcium hydroxide, calcium carbonate, and iron oxide used in this invention, after being compounded and mechanically ground to ≤200 mesh, exhibit altered physicochemical properties. Extensive data shows that the finer the particle size, the larger the specific surface area and the greater the surface free energy. When the stabilizer is smaller than 200 mesh and the heavy metal pollutants are one or more of cadmium, lead, arsenic, and zinc, with the arsenic content in the tailings ≤5000 mg / kg, the lead content ≤5000 mg / kg, and the zinc content ≤5000 mg / kg, the stabilizer can better mix thoroughly with the equally fine tailings and distribute evenly among the various minerals. Under the action of the reinforcing components and water, the stabilizer first undergoes a hydrolysis reaction and immediately undergoes a series of chemical reactions with heavy metals such as cadmium, arsenic, and zinc. XRD testing shows that it reacts with cadmium to form Cd4Al2O6C. l2 · 10H2O, reacts with arsenic to form Al2(AsO4)(OH)3·3H2O, reacts with zinc to form Zn5(OH)8Cl2·H2O, etc. (see ) Figure 2 , Figure 3 , Figure 4Example); Simultaneously, complex physicochemical mineralization processes such as agglomeration, polymerization, adsorption, and bridging occur. EDS analysis of stabilized lead-zinc mine tailings shows that heavy metals such as arsenic, copper, and lead react with iron and aluminum hydrolyzed micelles in the stabilizer to form polynuclear complexes, which are then solidified together. Figure 5 (Example) This invention significantly reduces the toxicity and leaching rate of heavy metals. Sodium silicate is used as a reinforcing agent, working synergistically with basic component A to stabilize the heavy metal minerals generated during the solidification process. The toxicity of the leached heavy metal pollutants from the stabilized lead-zinc mine tailings is far below the limits set by the "Integrated Wastewater Discharge Standard" (GB8978-1996). After stabilization, the lead-zinc mine tailings are transformed from Class II solid waste to Class I solid waste. Furthermore, the concentration of heavy metal pollutants in the leachate is lower than the Class III surface water standard limit, indicating a very low environmental pollution risk. Therefore, the lead-zinc mine tailings heavy metal stabilizer of this invention is a fast-acting and effective heavy metal solidification and stabilization agent.

[0031] The calcium carbonate and iron oxide in the stabilizer for controlling heavy metal pollution in lead-zinc mine tailings provided by this invention are poorly soluble in water, but can react with acid in acidic aqueous solutions. The acid produced by the oxidation of sulfide minerals in the tailings is immediately neutralized by the calcium carbonate and iron oxide, preventing further oxidation and precipitation of various heavy metal minerals in the tailings. This stabilizer has strong resistance to acid rain and acidification by sulfide minerals. Therefore, the lead-zinc mine tailings heavy metal stabilizer of this invention also has the function of stabilizing the pH of the solidified tailings. The solidified and stabilized tailings have good weather resistance and can effectively and stably reduce the leaching of heavy metal pollutants in lead-zinc mine tailings for a long time. As can be seen from the results in the examples (Table 1), after 300 days of open-air storage, the leaching toxicity remains unchanged and is still very low.

[0032] The lead-zinc mine tailings heavy metal stabilizer provided by this invention is mainly prepared by compounding and mechanically activating polyaluminum ferric chloride, polyferric sulfate calcium hydroxide, calcium carbonate, and iron oxide. All materials are industrial-grade products, widely available and inexpensive.

[0033] The amount of stabilizer used by weight is only 0.5% to 3% of that used in lead-zinc mine tailings. The amount used is small, and the volume increase of the tailings after treatment is minimal. It can simultaneously solidify and stabilize heavy metals such as cadmium, lead, and zinc in the tailings, as well as arsenic, a semi-metal with significantly different properties.

[0034] All components have extremely low toxicity and side effects, are environmentally friendly, and will not cause secondary pollution to the environment. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the stabilizer for controlling heavy metal pollutants in lead-zinc mine tailings and its application process according to the present invention.

[0036] Figure 2 The image shows the XRD pattern of the stabilizer of this invention reacting with cadmium (Cd).

[0037] Figure 3 The image shows the XRD pattern of the stabilizer of the present invention reacting with arsenic (As).

[0038] Figure 4 The image shows the XRD pattern of the stabilizer of the present invention reacting with zinc (Zn).

[0039] Figure 5 The stabilizers of this invention, iron and aluminum, react with arsenic, copper, lead, etc. to form polynuclear complexes (EDS diagram). Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0041] The stabilizer of this invention consists of a base component A and a reinforcing component B. Base component A is prepared by mechanical activation from the following components: polyaluminum ferric chloride, polyferric sulfate, calcium hydroxide, calcium carbonate, and iron oxide. Reinforcing component B is sodium silicate, prepared as an aqueous solution for use. When the heavy metal pollutants in lead-zinc mine tailings are one or more of cadmium, lead, arsenic, and zinc, and the arsenic content in the tailings is ≤5000 mg / kg, the lead content is ≤5000 mg / kg, and the zinc content is ≤5000 mg / kg, after the basic component A of the stabilizer is added to the lead-zinc mine tailings and mixed evenly, the basic component A, due to its fine particle size, can be evenly distributed among the tailings particles. After adding the aqueous solution of the reinforcing component B, the stabilizer hydrolyzes to produce polynuclear hydroxyl ions, chain colloids, etc., which react with the free heavy metal ions such as cadmium, arsenic, zinc, and lead in the tailings to generate a series of substances such as Cd4Al2O6Cl2·10H2O, Al2(AsO4)(OH)3·3H2O, and Zn5(OH)8Cl2·H2O (see...). Figure 2 , Figure 3 , Figure 4 (Example) On the other hand, it simultaneously undergoes a series of physicochemical reactions such as bridging, polymerization, and adsorption with water-soluble heavy metals and mineral particles, preventing the oxidation of sulfides and the leaching of heavy metals in the tailings. EDS test results of lead-zinc mine tailings after stabilization ( Figure 5 (Example) shows that heavy metals such as arsenic, copper, and lead react with iron and aluminum hydrolysates in the stabilizer to form polynuclear polymers, which are then bound together.

[0042] Control example (without stabilizer)

[0043] To better illustrate the effectiveness of this invention in stabilizing heavy metal pollutants, a leaching toxicity test was conducted on tailings from a lead-zinc mine without stabilizer treatment to investigate the water leaching dissolution of heavy metal pollutants in the tailings, serving as a control example. The heavy metal pollutant content of the tailings from the lead-zinc mine was arsenic 477.75 mg / kg, cadmium 250.5 mg / kg, lead 1120.75 mg / kg, copper 88.38 mg / kg, and zinc 9359.63 mg / kg.

[0044] The method for this comparative example (without stabilizer) involves taking unstabilized lead-zinc mine tailings and conducting leaching toxicity tests according to the requirements of the standard "Leaching Toxicity of Solid Waste - Horizontal Oscillation Method" (HJ557-2010). The relevant results are shown in Table 1. As can be seen from Table 1, the leachate from the unstabilized lead-zinc mine tailings had high levels of pH, zinc, cadmium, and arsenic, exceeding the limits set by the "Integrated Wastewater Discharge Standard" (GB8978-1996). According to relevant national standards, the lead-zinc mine tailings belong to Class II industrial solid waste. Furthermore, the levels of cadmium, arsenic, lead, and zinc in the leachate all exceeded the national surface water environmental quality standards, indicating that the lead-zinc mine tailings pose a significant environmental pollution risk.

[0045] Example 1

[0046] To illustrate the practical application effect of this invention, the stabilizer and application method for controlling heavy metal pollution of a lead-zinc mine tailings were used to solidify and stabilize heavy metal pollutants. The heavy metal pollutant content of the tailings of the lead-zinc mine was arsenic 477.75 mg / kg, cadmium 250.5 mg / kg, lead 1120.75 mg / kg, copper 88.38 mg / kg, and zinc 9359.63 mg / kg.

[0047] Combination Figure 1 The method for preparing the stabilizer and treating the lead-zinc mine tailings in this embodiment is as follows:

[0048] Step (1): Place 37 kg of polyaluminum ferric chloride, 11 kg of polyferric sulfate, 48 kg of calcium hydroxide, 3.0 kg of calcium carbonate, and 1.0 kg of iron oxide into a ball mill and grind them until all of them pass through a 200-mesh sieve; to obtain basic component A.

[0049] Step (2): Put 1158.50g of a lead-zinc mine tailings with a moisture content of 13.68% into a mixer;

[0050] Step (3): Take 30g of the stabilizer base component A obtained in step (1) and add it to the mixer in step (2) and mix it evenly with the lead-zinc ore tailings;

[0051] Step (4): Add 50 mL of a 0.3% sodium silicate aqueous solution to the material after the basic component A and lead-zinc ore tailings in step (3) are mixed evenly;

[0052] Step (5): The lead-zinc mine tailings with added stabilizer are cured for 24 hours and then stored in the open for 300 days.

[0053] Step (6): Samples were taken from the cured lead-zinc mine tailings and leaching tests were conducted according to the requirements of the standard "Leaching Toxicity Method for Solid Waste - Horizontal Oscillation Method" (HJ557-2010). The relevant test results for 24-hour and 300-day curing times are detailed in Table 1.

[0054] Heavy metals such as arsenic, cadmium, lead, and zinc in lead-zinc mine tailings exist in two phases based on their solubility: one is water-soluble substances containing one or more of these heavy metals; the other is water-insoluble sulfide minerals containing these heavy metals. These latter sulfide minerals are also easily oxidized in the presence of water and oxygen to form water-soluble substances. The stabilizer base component A of this invention, after being uniformly mixed with lead-zinc mine tailings, primarily functions to distribute evenly within the tailings particles. Adding the reinforcing component B (sodium silicate) aqueous solution forms multipolar colloids such as aluminum hydroxide and iron hydroxide, which aggregate arsenic, cadmium, lead, and zinc heavy metal ions and their soluble substances through chemical reactions and physical processes such as adsorption, bonding, bridging, and trapping (see details). Figure 5 This stabilizes and solidifies heavy metals such as arsenic, cadmium, lead, and zinc, preventing them from leaching into the water. Simultaneously, the multipolar colloids such as aluminum hydroxide and ferric hydroxide, along with the water-insoluble calcium carbonate and iron oxide in the stabilizer, further prevent the sulfide minerals containing heavy metals like arsenic, cadmium, lead, or zinc in the tailings from being further oxidized to form water-soluble substances. As shown in Table 1, compared to the control without stabilizer, the stabilizer of this invention has a fine particle size, uniform distribution, and rapid onset of action. After 24 hours of curing, the concentrations of heavy metal pollutants such as arsenic, cadmium, lead, and zinc in the leachate are lower than the limits set by the "Integrated Wastewater Discharge Standard" (GB8978-1996) and also lower than the Class III water standard limits of the "Surface Water Environmental Quality Standard." The solidification and stabilization effect of heavy metal pollutants such as arsenic, cadmium, lead, and zinc is very significant. Even after 300 days of open-air storage, the solidification and stabilization effect does not decrease, further demonstrating that the stabilizer of this invention has a clear mechanism and outstanding effect in solidifying and stabilizing heavy metal pollutants in lead-zinc mine tailings.

[0055] Example 2

[0056] To illustrate the practical application effect of this invention, the stabilizer and its application method were used to solidify and stabilize heavy metal pollutants in the tailings of a lead-zinc mine. The heavy metal pollutant content in the tailings of the lead-zinc mine was arsenic 477.75 mg / kg, cadmium 250.5 mg / kg, lead 1120.75 mg / kg, copper 88.38 mg / kg, and zinc 9359.63 mg / kg.

[0057] Combination Figure 1 The method for preparing the stabilizer and treating the lead-zinc mine tailings in this embodiment is as follows:

[0058] Step (1): Put 39 kg of polyaluminum ferric chloride, 11 kg of polyferric sulfate, 45 kg of calcium hydroxide, 4.0 kg of calcium carbonate, and 1.0 kg of iron oxide into a ball mill and grind them until they all pass through a 200-mesh sieve to obtain basic component A;

[0059] Step (2): Put 1158.50g of a lead-zinc mine tailings with a moisture content of 13.68% into a mixer;

[0060] Step (3): Take 15g of the stabilizer base component A obtained in step (1) and add it to the mixer in step (2) and mix it evenly with the lead-zinc ore tailings;

[0061] Step (4): Add 50 mL of 0.3% sodium silicate aqueous solution to the material after mixing the basic component A and lead-zinc ore tailings in step (3) and stir evenly;

[0062] Step (5): The lead-zinc mine tailings with added stabilizer are cured for 24 hours and then stored in the open for 300 days.

[0063] Step (6): Samples were taken from the cured lead-zinc mine tailings and leaching tests were conducted according to the requirements of the standard "Leaching Toxicity Method for Solid Waste - Horizontal Oscillation Method" (HJ557-2010). The test results after 24 hours of curing and 300 days of open-air storage are shown in Table 1.

[0064] Example 3

[0065] To illustrate the practical application effect of this invention, solidification and stabilization control of heavy metal pollutants in tailings of a lead-zinc mine was carried out. The heavy metal pollutant content in the tailings of the lead-zinc mine was arsenic 477.75 mg / kg, cadmium 250.5 mg / kg, lead 1120.75 mg / kg, copper 88.38 mg / kg, and zinc 9359.63 mg / kg.

[0066] Combination Figure 1 The method for preparing the stabilizer and treating the lead-zinc mine tailings in this embodiment is as follows:

[0067] Step (1): Put 45 kg of polyaluminum ferric chloride, 10 kg of polyferric sulfate, 40 kg of calcium hydroxide, 4.0 kg of calcium carbonate, and 1.0 kg of iron oxide into a ball mill and grind them until they all pass through a 200-mesh sieve to obtain basic component A;

[0068] Step (2): Take 5793g (dry weight 5000g) of tailings from a lead-zinc mine and put it into a mixer;

[0069] Step (3): Take 100g of the stabilizer base component A obtained in step (1) and add it to the mixer in step (2) and mix it evenly with the lead-zinc ore tailings;

[0070] Step (4): Add 700 mL of 0.3% sodium silicate aqueous solution to the material after mixing the basic component A and lead-zinc ore tailings in step (3) and stir evenly;

[0071] Step (5): Curing the solidified and stabilized product for 48 hours, followed by outdoor storage for 300 days;

[0072] Step (6): Samples were taken from the cured lead-zinc mine tailings and leaching tests were conducted according to the requirements of the standard "Leaching Toxicity Method for Solid Waste - Horizontal Oscillation Method" (HJ557-2010). The test results after 24 hours of curing and 300 days of open-air storage are shown in Table 1.

[0073] Example 4

[0074] To illustrate the practical application effect of this invention, solidification and stabilization control of heavy metal pollutants in tailings of a lead-zinc mine was carried out. The heavy metal pollutant content in the tailings of the lead-zinc mine was arsenic 477.75 mg / kg, cadmium 250.5 mg / kg, lead 1120.75 mg / kg, copper 88.38 mg / kg, and zinc 9359.63 mg / kg.

[0075] Combination Figure 1 The methods for preparing the stabilizer and treating lead-zinc mine tailings in this embodiment are as follows:

[0076] Step (1): 43 kg of polyaluminum ferric chloride, 12 kg of polyferric sulfate, 30 kg of calcium hydroxide, 14.5 kg of calcium carbonate, and 0.5 kg of iron oxide were put into a ball mill and ground until they all passed through a 200-mesh sieve to obtain basic component A;

[0077] Step (2): Take 5793g (dry weight 5000g) of tailings from a lead-zinc mine and put it into a mixer;

[0078] Step (3): Take 100g of the stabilizer base component A obtained in step (1) and add it to the mixer in step (2) and mix it evenly with the lead-zinc ore tailings;

[0079] Step (4): Add 700 mL of 0.1% sodium silicate aqueous solution to the material after mixing the basic component A and lead-zinc ore tailings in step (3) and stir evenly;

[0080] Step (5): Curing the solidified and stabilized product for 48 hours, followed by outdoor storage for 300 days;

[0081] Step (6): Samples were taken from the cured lead-zinc mine tailings and leaching tests were conducted according to the requirements of the standard "Leaching Toxicity Method for Solid Waste - Horizontal Oscillation Method" (HJ557-2010). The test results after 24 hours of curing and 300 days of open-air storage are shown in Table 1.

[0082] Table 1. Stabilization test results of lead-zinc mine tailings (Method HJ557-2010) (Unit: mg / L)

[0083] .

[0084] The above data indicates that when the heavy metal pollutants in lead-zinc mine tailings are one or more of cadmium, lead, arsenic, and zinc, and the arsenic content in the tailings is ≤5000 mg / kg, the lead content is ≤5000 mg / kg, and the zinc content is ≤5000 mg / kg, and the stabilizer particles are smaller than 200 mesh, it can better mix thoroughly with the equally fine lead-zinc mine tailings and distribute evenly among various minerals. Under the action of the reinforcing components and water, polyaluminum ferric chloride and calcium hydroxide undergo hydrolysis and immediately react with heavy metals such as cadmium, arsenic, lead, and zinc in a series of chemical reactions, generating a series of stable substances such as Cd4Al2O6Cl2·10H2O, Al2(AsO4)(OH)3·3H2O, and Zn5(OH)8Cl2·H2O. See details... Figure 2 , Figure 3 , Figure 4 Example. Simultaneously, complex physicochemical mineralization processes such as agglomeration, polymerization, and physical adsorption occur, such as... Figure 5 Arsenic, copper, lead, and other heavy metals in the solution react with iron and aluminum to form polynuclear polymers, which are then solidified together, significantly reducing the toxicity and leaching rate of the heavy metals. Sodium silicate is selected as a reinforcing agent, which works synergistically with the basic component A to make the heavy metal minerals generated during the solidification and stabilization process more stable. After stabilization, the lead-zinc mine tailings are transformed from Class II solid waste to Class I solid waste, greatly reducing the risk of environmental pollution. As can be seen from the examples (Table 1), the concentration of heavy metal pollutants in the toxic leachate after stabilization is far lower than the limit of the Integrated Wastewater Discharge Standard (GB8978-1996) and also lower than the corresponding limit of Class III water quality standard of the Surface Water Environmental Quality Standard. The concentrations of cadmium, lead, arsenic, and zinc in the leachate decreased from 120 mg / L, 0.502 mg / L, 1.33 mg / L, and 0.5 mg / L before solidification and stabilization to below 0.016 mg / L, 0.0232 mg / L, 0.00341 mg / L, and 0.001 mg / L after stabilization, respectively, with solidification rates reaching 99.98%, 95.38%, 99.74%, and 99.8%. This demonstrates that the stabilizer for controlling heavy metal pollution in lead-zinc mine tailings according to the present invention is a fast-acting and effective heavy metal solidification and stabilization agent.

[0085] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A stabilizer for controlling heavy metal pollution of lead-zinc mine tailings, characterized by: The stabilizer comprises a base component A and a reinforcing component B; The base component A is: 37 kg of polyaluminum ferric chloride, 11 kg of polyferric sulfate, 48 kg of calcium hydroxide, 3.0 kg of calcium carbonate, and 1.0 kg of iron oxide; The reinforcing component B is a 0.3% sodium silicate aqueous solution; The polyaluminum ferric chloride, polyferric sulfate, calcium hydroxide, calcium carbonate, and iron oxide are placed in a grinding device, ground to ≤200 mesh, and mechanically activated to obtain the base component A; The polyaluminum ferric chloride is an industrial product with ≥26% aluminum oxide, 3%-6% iron oxide, ≥65% basicity, and ≤0.0003% arsenic; The calcium hydroxide, polyferric sulfate, calcium carbonate, iron oxide, and sodium silicate are industrial products; The heavy metal pollutants are one or more of cadmium, lead, arsenic, and zinc, with the content of arsenic in the tailings being ≤5000 mg / kg, the content of lead being ≤5000 mg / kg, and the content of zinc being ≤5000 mg / kg.

2. The method of using the stabilizer of claim 1, wherein, The method comprises the following steps: Step one: the base component A is mixed with the lead-zinc mine tailings to obtain a mixture; Step two: a 0.3% sodium silicate aqueous solution is prepared as the reinforcing component B; Step three: the aqueous solution of step two is added to the tailings of step one to obtain a solidified and stabilized body; the water content of the solidified and stabilized body is 15%-40%.

3. The method of using the stabilizing agent of claim 1, wherein: 1158.50 g of lead-zinc mine tailings with a water content of 13.68% are mixed with 30 g of the base component A of the stabilizer; 50 mL of a 0.3% sodium silicate aqueous solution is added as the reinforcing component B; and the lead-zinc mine tailings with the added stabilizer are cured for 24 hours.

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