Synchronous stabilization agent for soluble heavy metal in solid waste as well as preparation method and application of synchronous stabilization agent

Abstract

The invention discloses an agent for synchronously stabilizing soluble heavy metals in solid wastes as well as a preparation method and application of the agent, and belongs to the technical field of heavy metal pollution treatment. The agent for synchronously stabilizing the soluble heavy metals in the solid wastes comprises the following components in parts by weight: 30-60 parts of a substrate material, 20-30 parts of a main auxiliary material and 20-50 parts of a secondary auxiliary material, wherein the substrate material is modified kaolin and oyster shell powder, the main auxiliary material is any one of carbide slag, calcium hydroxide and calcium oxide, and the secondary auxiliary material is at least two of sepiolite, potassium hydrogen phosphate, struvite, wollastonite and silicon fertilizer. According to the stabilizing agent prepared by the method, the leaching toxicity of solid wastes with different heavy metal leaching toxicity levels can be greatly reduced, synchronous stabilization of four heavy metals of Zn, Cd, Pb and Mn can be realized, the cost is low, the application range is wide, and the pH of the solid wastes cannot be greatly increased.

Description

Technical Field

[0001] The invention relates to the technical field of heavy metal pollution treatment, and in particular to a simultaneous stabilization agent for soluble heavy metals in solid wastes, and a preparation method and application thereof. Background Art

[0002] Heavy metal leaching toxicity is a common and main toxic characteristic of solid waste / hazardous waste, and is also the main cause of the spread and migration of heavy metal pollution in solid waste / hazardous waste. It has always been a key and difficult problem in the prevention and control of solid waste / hazardous waste and heavy metal pollution. The control of soluble heavy metal leaching toxicity in solid waste has become one of the key measures to achieve pollution control and safe utilization and disposal throughout the process.

[0003] The technologies to reduce the toxicity of heavy metal leaching from solid waste / hazardous waste mainly include solidification (cement, geopolymer, etc.) and agent stabilization, among which the commonly used stabilization agents mainly include inorganic agents, organic agents and biomass materials. At present, the development of stabilization agents for soluble heavy metals in hazardous waste mainly focuses on achieving easy availability, low cost, low dosage, wide applicability, high stabilization rate, long-term effectiveness and pH reduction.

[0004] In recent years, the technology of heavy metal solidification and stabilization of solid waste has developed rapidly. Heavy metal solidification and stabilization technology (S / S) is to add a solidifying agent to solid waste, adjust and change the physical and chemical properties of solid waste, change the form of heavy metals in solid waste through a series of chemical reactions, reduce its mobility and biological effectiveness, and achieve the purpose of heavy metal stabilization of solid waste. The mechanism of solidification and stabilization effect is mainly to change the form of heavy metals in solid waste, which is achieved through precipitation, adsorption, coordination, organic complexation and redox.

[0005] The research on heavy metal solidification and stabilization, and the research and development of heavy metal solidifiers are one of the focuses. At present, the research and development of heavy metal solidifiers at home and abroad is progressing rapidly. According to the different material properties and structures and the solidification mechanism of heavy metals, soil heavy metal solidifiers are generally divided into inorganic stabilization materials, organic stabilization materials and redox materials.

[0006] Inorganic stabilization materials mainly include calcium-silicon materials, clay mineral materials, phosphate materials, etc. Inorganic solidification stabilization materials are used in different types of heavy metal contaminated sites, mainly through adsorption, chemical precipitation, interlayer ion exchange and other mechanisms to achieve the solidification and stabilization of heavy metals. Due to its wide source, low cost and good application effect, it is widely used.

[0007] Organic stabilization materials can also effectively improve the solidification of heavy metals in solid waste. Currently, humic acid and biochar materials are widely used. The main principle is to increase the pH of solid waste, increase its cation exchange capacity, form insoluble metal complexes, and reduce the bioavailability of heavy metals.

[0008] Redox materials are mainly metals and metal oxides, which are one of the natural components with low content in soil, with small particle size and low solubility. The main repair mechanism of metals and metal oxides for heavy metal contaminated soil is to fix the metals through surface adsorption and co-precipitation experiments. In addition to the conventional adsorption effect, some metal oxides have strong oxidizing properties and change the valence state of the metal. At present, the redox materials for the treatment of heavy metal pollution in solid waste soil are mainly iron and manganese oxides.

[0009] In addition to common organic and inorganic passivators, nanomaterial curing agents have also attracted much attention. Nanomaterials have a large specific surface area and high reactivity. In heavy metal contaminated soils, the passivation of heavy metals by nanomaterials is generally a combination of adsorption, coprecipitation, and redox mechanisms. Porous nano-modified materials (PNM) were applied to potted plant experiments. The study found that the effective content of soil showed a decreasing trend with the increase in the amount of PNM applied, while the pH value showed an increasing trend, indicating that PNM has a passivating effect on the activity of soil Cd and Pb, and can increase soil pH, indirectly reducing the biological effectiveness of Cd and Pb.

[0010] The development of heavy metal solidification and stabilization agents is one of the focuses of attention at home and abroad. For the remediation of heavy metal contaminated sites, agent development focuses on the recycling and optimization of industrial and agricultural wastes, and determines the parameters of stabilization agents for different types of contaminated sites and application targets by adjusting indicators such as the particle size, pH, and effective ingredient ratio of the solidifying agent.

[0011] (1) Screening and comparison of heavy metal solidification and stabilization materials

[0012] According to the properties and mechanism of action of the curing agent, heavy metal curing agents are generally divided into: inorganic stabilization materials, organic stabilization materials and new stabilization materials. The selection of curing stabilization materials should be based on the characteristics of different types of materials, combined with the degree of soil heavy metal pollution and restoration and utilization. The selection methods include material performance comparison method, test comparison method, etc.

[0013] (2) Optimized compounding method of heavy metal solidification and stabilization materials

[0014] Optimizing compounding based on the complementary functions of different solidification and stabilization materials is one of the important methods for solidification and stabilization of heavy metals in solid waste soil, and it is also an important way to improve its restoration effect and reduce restoration costs. Peng Licheng compared the compound materials (0.25g / kg humic acid + 2g / kg water retaining agent + 10g / kg zeolite) with single materials to significantly reduce the concentration of heavy metal Cd in soil column leaching solution and reduce the biological effectiveness of heavy metals in contaminated soil; Gao Ruili et al. mixed biochar and montmorillonite in equal proportions and added them to soil contaminated with heavy metals. It was found that the material mixing treatment could reduce the weak acid extractable content of Pb and Cd by 15.9% and 12.0%, respectively, and increase the residual content by 110.1% and 62.5%, respectively, significantly reducing the mobility of heavy metals in soil.

[0015] (3) Surface modification method of heavy metal solidified and stabilized materials

[0016] In order to improve the adsorption and solidification effect of solidified and stabilized materials on heavy metals, they are generally subjected to surface modification treatments, which mainly include surface physical modification and surface chemical modification. Physical modification includes thermal modification, ultrasonic modification, etc., the purpose of which is to increase the specific surface area of ​​the material and form developed pores. Appropriate heating can remove adsorbed water, crystal water, etc. in the structure or activate active sites to improve the adsorption capacity. Long Liangjun subjected humic acid to thermal modification and found through scanning electron microscopy (SEM) that the surface of the modified humic acid was rough with numerous non-uniform pores, the O / C atomic ratio was reduced, and the oxygen-containing functional groups were reduced. However, when the temperature exceeded 490°C, the humic acid structure was destroyed and the adsorption capacity was reduced; ultrasonic modification can increase the adsorption volume and adsorption rate of the material and change the pore size of the material. Min Min found that the introduction of ultrasound can make activated carbon adsorb Cr. 4+ The adsorption equilibrium is advanced.

[0017] Surface chemical modification mainly includes surface oxidation modification, reduction modification, metal loading modification, etc. Oxidation modification mainly uses oxidants to react with the material surface at an appropriate temperature to increase the oxygen-containing functional groups of the solidified and stabilized materials, enhance the polarity of the materials and improve the ability to adsorb heavy metals. At present, the commonly used oxidants are mainly HNO3, H2O2, HCl, etc. Li Xinyue et al. used hydrogen peroxide to modify biochar to increase the pore structure and oxygen-containing functional groups, and biochar was more effective for Sb 3+ The adsorption rate reached 59.4%. It is worth noting that strong oxidizing properties will destroy the microporous structure of the material, resulting in a decrease in adsorption performance. Therefore, when oxidizing and modifying the material, attention should be paid to the selection of oxidant type and concentration.

[0018] In addition, the reduction modification of the functional groups on the surface of the material by a reducing agent at an appropriate temperature is also an important method for curing and stabilizing the material modification. The effect and mechanism is to increase the content of oxygen-containing alkaline groups and enhance the non-polarity of the material surface. Commonly used reducing agents include NaOH, Ca(OH)2, ammonia water, etc. Lei Chang et al. stirred fly ash and NaOH solution at a solid-liquid ratio of 1:5. When the amount of modified material was 5g / L and the initial Pb 2+ Under the conditions of concentration 100 mg / L, pH 5, temperature 25°C, and time 180 min, the modified material has a significant effect on Pb 2+ The removal rate reached 80.2%.

[0019] (4) Loading or bridging method of heavy metal solidification stabilization materials

[0020] The solidification and stabilization material loading is to load another material on the surface of the material to enhance the adsorption or redox of heavy metal ions. Generally, the metal ions loaded by high-temperature impregnation increase the number of active sites and acidic functional groups on the surface of the material, thereby improving the adsorption capacity of heavy metal ions. Currently, the metal ions commonly loaded by the solidification and stabilization material include copper ions, iron ions, etc. Mao Lingjun can make the activated carbon adsorb Cr by loading ferric chloride on activated carbon. 4+ The capacity was increased by 17%; Zhou Litao loaded chitosan onto the zeolite matrix to improve the removal effect of heavy metals and the mechanical strength of chitosan. Some materials or compounds can be prepared by bridging to modify materials, effectively improving material performance.

[0021] However, the current technology for stabilizing soluble heavy metals in solid waste still has the following shortcomings and problems:

[0022] (1) Currently, the application scope of stabilization agents for soluble heavy metals in solid waste is relatively narrow. On the one hand, they are only applicable to a narrow range of leaching toxicity levels and cannot be used to stabilize high-concentration soluble heavy metals. On the other hand, the types of soluble heavy metals that can be used are relatively limited, and usually only one or two soluble heavy metals can be stabilized.

[0023] (2) Currently, there is little research on stabilization agents and technologies for soluble heavy metals in solid wastes, especially hazardous wastes with high leaching toxicity levels. More focus is on the stabilization of heavy metals in soil. The two types of stabilization agents have obvious differences in their effects. Usually, soil heavy metal stabilization is mainly aimed at reducing the bioavailability of heavy metals. At the same time, due to the low concentration of soluble heavy metals in soil, this type of stabilization agent is usually not used in solid waste.

[0024] (3) In actual application, the stabilization of solid waste is usually directly related to the utilization and disposal of solid waste. The stabilized solid waste usually needs to be utilized and disposed of under complex conditions, and the time period for utilization and disposal is usually decades. This places high demands on the long-term effectiveness of solid waste stabilization agents. Most of the existing solid waste stabilization agents lack long-term effectiveness, and the stabilization effect is mostly concentrated in the short term. It is difficult to guarantee long-term effectiveness under complex environmental conditions, and they cannot be actually applied to the safe utilization and disposal of solid waste.

[0025] (4) The application of solid waste stabilization agents is also limited by the cost of using the agents. The preparation process of some existing stabilization agents is complicated, and the prices of raw and auxiliary materials are relatively high, resulting in high preparation costs. At the same time, the cost of using stabilization agents is also closely related to the amount of agents added. Especially for hazardous wastes with high leaching toxicity, if the stabilization efficiency is low, the agent addition ratio may be too high, resulting in impractical application.

[0026] (5) The most common solid waste stabilization agents at present are alkaline stabilization agents such as lime. Although the effect of alkaline stabilization agents is relatively obvious, they can easily cause a sharp increase in the pH value of solid waste. Not only is it easy to exceed the standard limit of the "Hazardous Waste Landfill Pollution Control Standard" (GB 18598-2019), it may even exceed the limit of the "Hazardous Waste Identification Standard Corrosive Identification", thereby causing secondary pollution and limiting the application of alkaline stabilization agents. Summary of the invention

[0027] In order to solve the above technical problems, the purpose of the present invention is to provide a synchronous stabilization agent for soluble heavy metals in solid waste and its preparation method and application, so as to solve the problems of narrow application range of existing solid waste heavy metal stabilization agents, poor stabilization ability for high-concentration soluble heavy metals, high preparation cost, high usage and easy to cause a sharp increase in the pH of solid waste.

[0028] The technical solution of the present invention to solve the above technical problems is as follows:

[0029] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight: 30-60 parts of a base material, 20-30 parts of a main auxiliary material, and 20-50 parts of a secondary auxiliary material;

[0030] Among them, the base materials are modified kaolin and oyster shell powder, the main auxiliary materials are any one of carbide slag, calcium hydroxide and calcium oxide, and the secondary auxiliary materials are at least two of sepiolite, potassium hydrogen phosphate, struvite, wollastonite and silicon fertilizer.

[0031] Furthermore, the following components are included in parts by weight: 40-50 parts of base material, 20-30 parts of main auxiliary materials and 30-40 parts of secondary auxiliary materials.

[0032] Furthermore, the following components are included in parts by weight: 45 parts of base material, 20 parts of main auxiliary materials and 35 parts of secondary auxiliary materials.

[0033] Furthermore, the mass ratio of modified kaolin and oyster shell powder in the base material is (3-6): (2-5).

[0034] Furthermore, the modified kaolin is prepared by the following method: kaolin is calcined at high temperature and then cooled.

[0035] Furthermore, the conditions for high temperature calcination are: heating to 1200-1400° C. at a heating rate of 5-10° C. / min and keeping the temperature for 2-3 hours.

[0036] The preparation method of the above-mentioned soluble heavy metal synchronous stabilization agent in solid waste comprises the following steps: grinding the raw materials, drying them, and then mixing them evenly to obtain the obtained product.

[0037] Furthermore, the raw material after grinding is sieved through 100-200 mesh and dried to a moisture content of ≤3%.

[0038] The application of the above-mentioned soluble heavy metal synchronous stabilization agent in solid waste to reduce the content of heavy metals Zn, Cd, Pb and Mn in solid waste.

[0039] The present invention has the following beneficial effects:

[0040] (1) The present invention prepares a widely applicable stabilizing agent for soluble heavy metals in solid waste / hazardous waste. The wide applicability of the agent is mainly reflected in the ability to significantly reduce the leaching toxicity of solid wastes with different heavy metal leaching toxicity levels, especially the ability to stabilize hazardous wastes with high leaching toxicity levels of soluble heavy metals such as Zn and Cd, represented by lead and zinc smelting waste slag. The leaching toxicity levels of heavy metals such as Zn and Cd in lead and zinc smelting waste slag that exceed the leaching toxicity standard limit of hazardous wastes by 10-30 times can be steadily reduced to below the admission standard limit of the "Hazardous Waste Landfill Pollution Control Standard", and the leaching toxicity reduction rate of Zn and Cd exceeds 95%, with the highest reaching 99%. At the same time, the stabilizing agent prepared by the present invention is also suitable for the stabilization of solid wastes with low levels of leaching toxicity.

[0041] (2) The stabilization agent provided by the present invention can simultaneously stabilize the four soluble heavy metals Zn, Cd, Pb, and Mn in solid waste, significantly reducing the leaching toxicity level of the four heavy metals, and the leaching toxicity reduction rate can reach more than 99%.

[0042] (3) The stabilizing agent provided by the present invention has low-cost main raw materials that are easy to obtain, and solid waste is used as the raw material of the stabilizing agent, which further reduces the preparation cost. In addition, the preparation method of the agent is simple, the stabilization efficiency is high, the use and addition ratio is limited, and the overall stabilization cost is low.

[0043] (4) The stabilization agent provided by the present invention can achieve the simultaneous stabilization of the four soluble heavy metals Zn, Cd, Pb and Mn in solid waste without causing a significant increase in the pH value of the solid waste. The pH value of the solid waste after stabilization is controllable as a whole.

[0044] (5) The stabilization agent provided by the present invention is a stabilization agent system based on more than ten kinds of basic stabilization agent raw materials. It can be used for different types of solid wastes. It can be adjusted according to actual conditions during actual application, and selective configuration of basic stabilization agents can be carried out in a targeted manner. The prepared stabilization agent can meet the stabilization needs of different application scenarios and different types of solid wastes. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is the XRD pattern of modified kaolin;

[0046] Figure 2 This is a diagram of the Zn stabilization effect in the test example;

[0047] Figure 3 This is a diagram of the Cd stabilization effect in the test example;

[0048] Figure 4 This is a diagram of the Pb stabilization effect in the test example;

[0049] Figure 5 This is a diagram of the Mn stabilization effect in the test example;

[0050] Figure 6 The stabilization effect of modified kaolin, sepiolite, struvite and silicon fertilizer on four heavy metals is shown in the figure;

[0051] Figure 7 This is a diagram showing the stabilization effects of calcium oxide, calcium hydroxide, potassium dihydrogen phosphate and oyster shell powder on four heavy metals. DETAILED DESCRIPTION

[0052] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0053] Embodiment 1:

[0054] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0055] 25 parts of modified kaolin, 20 parts of oyster shell powder, 20 parts of carbide slag, 15 parts of sepiolite and 20 parts of silicon fertilizer.

[0056] The modified kaolin is prepared by the following method: calcining the kaolin at a heating rate of 5°C / min to 1300°C, keeping the temperature for 3 hours, cooling to room temperature, and then taking out the modified kaolin with mullite as the main component. The XRD spectrum of the modified kaolin is as follows: Figure 1 As shown, the modified kaolin is mainly composed of mullite.

[0057] The method for preparing the above-mentioned agent for simultaneously stabilizing soluble heavy metals in solid waste comprises the following steps:

[0058] The raw material components are ground to 200 meshes respectively, and then dried to a moisture content of ≤3%, and finally mixed evenly by dry mixing to obtain a product named GH-3.

[0059] Embodiment 2:

[0060] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0061] 25 parts of modified kaolin, 20 parts of oyster shell powder, 20 parts of calcium chloride, 15 parts of struvite and 20 parts of silicon fertilizer.

[0062] The preparation method is the same as that of Example 1 and the compound is named GH-5.

[0063] Embodiment 3:

[0064] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0065] 25 parts of modified kaolin, 20 parts of oyster shell powder, 20 parts of calcium hydroxide, 15 parts of struvite, 10 parts of potassium hydrogen phosphate and 10 parts of wollastonite.

[0066] The preparation method is the same as that of Example 1 and the compound is named GH-6.

[0067] Embodiment 4:

[0068] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0069] 20 parts of modified kaolin, 25 parts of oyster shell powder, 20 parts of calcium chloride, 15 parts of sepiolite and 20 parts of wollastonite.

[0070] The preparation method is the same as that of Example 1 and the compound is named GH-7.

[0071] Embodiment 5:

[0072] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0073] 20 parts of modified kaolin, 25 parts of oyster shell powder, 20 parts of carbide slag, 10 parts of sepiolite, 10 parts of potassium hydrogen phosphate and 15 parts of silicon fertilizer.

[0074] The preparation method is the same as that of Example 1 and the compound is named GH-13.

[0075] Embodiment 6:

[0076] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0077] 25 parts of modified kaolin, 20 parts of oyster shell powder, 20 parts of carbide slag, 10 parts of wollastonite, 10 parts of sepiolite and 15 parts of silicon fertilizer.

[0078] The preparation method is the same as that of Example 1 and the compound is named GH-14.

[0079] Embodiment 7:

[0080] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0081] 30 parts of modified kaolin, 15 parts of oyster shell powder, 20 parts of calcium chloride, 15 parts of struvite and 20 parts of silicon fertilizer.

[0082] The preparation method is the same as that of Example 1 and the compound is named GH-15.

[0083] Embodiment 8:

[0084] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0085] 30 parts of modified kaolin, 15 parts of oyster shell powder, 20 parts of carbide slag, 15 parts of sepiolite and 20 parts of wollastonite.

[0086] The preparation method is the same as that of Example 1 and the compound is named GH-27.

[0087] Embodiment 9:

[0088] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0089] 30 parts of modified kaolin, 15 parts of oyster shell powder, 20 parts of calcium hydroxide, 15 parts of sepiolite, 10 parts of wollastonite and 10 parts of struvite.

[0090] The preparation method is the same as that of Example 1 and the compound is named GH-29.

[0091] Comparative Example 1:

[0092] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0093] 25 parts of kaolin, 20 parts of oyster shell powder, 20 parts of carbide slag, 15 parts of sepiolite and 20 parts of silicon fertilizer.

[0094] The preparation method is the same as that of Example 1 and is named GH-1.

[0095] Comparative Example 2:

[0096] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0097] 25 parts of kaolin, 20 parts of oyster shell powder, 20 parts of calcium chloride, 15 parts of struvite and 20 parts of silicon fertilizer.

[0098] The preparation method is the same as that of Example 1 and is named GH-4.

[0099] Comparative Example 3:

[0100] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0101] 25 parts of kaolin, 20 parts of oyster shell powder, 20 parts of calcium hydroxide, 15 parts of struvite, 10 parts of potassium hydrogen phosphate and 10 parts of wollastonite.

[0102] The preparation method is the same as that of Example 1 and the compound is named GH-8.

[0103] Comparative Example 4:

[0104] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0105] 20 parts of kaolin, 25 parts of oyster shell powder, 20 parts of calcium chloride, 15 parts of sepiolite and 20 parts of wollastonite.

[0106] The preparation method is the same as that of Example 1 and the compound is named GH-9.

[0107] Comparative Example 5:

[0108] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0109] 20 parts of kaolin, 25 parts of oyster shell powder, 20 parts of carbide slag, 10 parts of sepiolite, 10 parts of potassium hydrogen phosphate and 15 parts of silicon fertilizer.

[0110] The preparation method is the same as that of Example 1 and the compound is named GH-12.

[0111] Comparative Example 6:

[0112] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0113] 25 parts of kaolin, 20 parts of oyster shell powder, 20 parts of carbide slag, 10 parts of wollastonite, 10 parts of sepiolite and 15 parts of silicon fertilizer.

[0114] The preparation method is the same as that of Example 1 and the compound is named GH-18.

[0115] Comparative Example 7:

[0116] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0117] 30 parts of kaolin, 15 parts of oyster shell powder, 20 parts of calcium chloride, 15 parts of struvite and 20 parts of silicon fertilizer.

[0118] The preparation method is the same as that of Example 1 and the compound is named GH-21.

[0119] Comparative Example 8:

[0120] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0121] 30 parts of kaolin, 15 parts of oyster shell powder, 20 parts of carbide slag, 15 parts of sepiolite and 20 parts of wollastonite.

[0122] The preparation method is the same as that of Example 1 and the compound is named GH-24.

[0123] Comparative Example 9:

[0124] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0125] 30 parts of kaolin, 15 parts of oyster shell powder, 20 parts of calcium hydroxide, 15 parts of sepiolite, 10 parts of wollastonite and 10 parts of struvite.

[0126] The preparation method is the same as that of Example 1 and the compound is named GH-26.

[0127] Comparative Example 10:

[0128] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0129] 30 parts of kaolin, 15 parts of oyster shell powder, 20 parts of carbide slag, 15 parts of sepiolite, 10 parts of wollastonite and 10 parts of struvite.

[0130] The preparation method is the same as that of Example 1 and the compound is named GH-28.

[0131] Comparative Example 11:

[0132] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0133] 30 parts of kaolin, 15 parts of oyster shell powder, 20 parts of calcium chloride, 15 parts of potassium hydrogen phosphate, 10 parts of wollastonite and 10 parts of struvite.

[0134] The preparation method is the same as that of Example 1 and the product is named GH-35.

[0135] Comparative Example 12:

[0136] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0137] 45 parts of kaolin, 20 parts of carbide slag, 15 parts of sepiolite and 20 parts of silicon fertilizer.

[0138] The preparation method is the same as that of Example 1 and the compound is named GH-16.

[0139] Comparative Example 13:

[0140] A synchronous stabilization agent for soluble heavy metals in solid waste comprises the following components in parts by weight: 45 parts of kaolin, 20 parts of calcium chloride, 15 parts of struvite and 20 parts of silicon fertilizer.

[0141] The preparation method is the same as that of Example 1 and the product is named GH-20.

[0142] Comparative Example 14:

[0143] A simultaneous stabilization agent for soluble heavy metals in solid wastes comprises the following components by weight: 45 parts of kaolin, 20 parts of calcium hydroxide, 15 parts of struvite, 10 parts of potassium hydrogen phosphate and 10 parts of wollastonite. The preparation method is the same as that of Example 1 and the agent is named GH-25.

[0144] Comparative Example 15:

[0145] A simultaneous stabilization agent for soluble heavy metals in solid wastes comprises the following components by weight: 45 parts of kaolin, 20 parts of carbide slag, 15 parts of struvite, 10 parts of potassium hydrogen phosphate and 10 parts of wollastonite. The preparation method is the same as that of Example 1 and the agent is named GH-19.

[0146] Comparative Example 16:

[0147] A simultaneous stabilization agent for soluble heavy metals in solid wastes comprises the following components by weight: 45 parts of kaolin, 20 parts of calcium oxide, 15 parts of struvite, 10 parts of potassium hydrogen phosphate and 10 parts of wollastonite. The preparation method is the same as that of Example 1 and the agent is named GH-22.

[0148] Comparative Example 17:

[0149] A simultaneous stabilization agent for soluble heavy metals in solid wastes comprises the following components by weight: 45 parts of kaolin, 20 parts of calcium hydroxide, 15 parts of struvite, 10 parts of sepiolite and 10 parts of silicon fertilizer. The preparation method is the same as that of Example 1 and the agent is named GH-22.

[0150] Comparative Example 18:

[0151] A simultaneous stabilization agent for soluble heavy metals in solid wastes comprises the following components by weight: 45 parts of kaolin, 20 parts of carbide slag, 15 parts of sepiolite, 10 parts of potassium hydrogen phosphate and 10 parts of wollastonite. The preparation method is the same as that of Example 1 and the agent is named GH-30.

[0152] Comparative Example 19:

[0153] A simultaneous stabilization agent for soluble heavy metals in solid wastes comprises the following components by weight: 35 parts of kaolin, 20 parts of oyster shell powder, 15 parts of sepiolite, 15 parts of wollastonite and 15 parts of struvite. The preparation method is the same as that of Example 1 and the agent is named GH-2.

[0154] Comparative Example 20:

[0155] A simultaneous stabilization agent for soluble heavy metals in solid wastes comprises the following components by weight: 35 parts of kaolin, 20 parts of oyster shell powder, 15 parts of potassium hydrogen phosphate, 15 parts of wollastonite and 15 parts of struvite. The preparation method is the same as that of Example 1 and the agent is named GH-10.

[0156] Comparative Example 21:

[0157] A synchronous stabilization agent for soluble heavy metals in solid waste comprises the following components in parts by weight: 35 parts of kaolin, 20 parts of oyster shell powder, 15 parts of sepiolite, 15 parts of struvite and 15 parts of silicon fertilizer.

[0158] The preparation method is the same as that of Example 1 and the compound is named GH-11.

[0159] Comparative Example 22:

[0160] A synchronous stabilization agent for soluble heavy metals in solid waste comprises the following components in parts by weight: 60 parts of kaolin, 20 parts of carbide slag and 20 parts of calcium oxide.

[0161] The preparation method is the same as that of Example 1 and the compound is named GH-17.

[0162] Comparative Example 23:

[0163] A synchronous stabilization agent for soluble heavy metals in solid waste comprises the following components in parts by weight: 60 parts of kaolin, 20 parts of carbide slag and 20 parts of calcium hydroxide.

[0164] The preparation method is the same as that of Example 1 and the compound is named GH-31.

[0165] Comparative Example 24:

[0166] A synchronous stabilization agent for soluble heavy metals in solid waste comprises the following components in parts by weight: 60 parts of kaolin, 20 parts of calcium hydroxide and 20 parts of calcium oxide.

[0167] The preparation method is the same as that of Example 1 and the compound is named GH-32.

[0168] Comparative Example 25:

[0169] A synchronous stabilization agent for soluble heavy metals in solid waste comprises the following components in parts by weight: 50 parts of kaolin, 25 parts of carbide slag and 25 parts of calcium oxide.

[0170] The preparation method is the same as that of Example 1 and the compound is named GH-33.

[0171] Comparative Example 26:

[0172] A simultaneous stabilization agent for soluble heavy metals in solid wastes, comprising the following components in parts by weight:

[0173] 50 parts of kaolin, 25 parts of calcium hydroxide and 25 parts of calcium oxide.

[0174] The preparation method is the same as that of Example 1 and the compound is named GH-34.

[0175] Test example:

[0176] The wet zinc smelting leaching slag was prepared. The wet zinc smelting leaching slag was collected from a wet electrolytic zinc smelter in Shimian County, Sichuan Province. The heavy metal content and heavy metal leaching toxicity level of the leaching slag (leached by sulfuric acid-nitric acid method, HJ / T 299) are shown in Table 1. The contents of heavy metals such as Zn, Pb, Mn, Cu, As, and Cd in the leaching slag are all over 0.1%, but the soluble heavy metals are mainly Zn, Mn, and Cd. The leaching toxicity levels of Zn and Cd exceed the standard limits of "Hazardous Waste Identification Standard Leaching Toxicity Identification" (GB5085.3-2007) by 9 times and 17 times, respectively, and Mn reaches 45.2±3.0 mg / L. The leaching concentration of Cd exceeds the standard limit of "Hazardous Waste Landfill Pollution Control Standard" (GB18598-2019) by 29 times.

[0177] Table 1 Heavy metal content and leaching toxicity level in zinc smelting leaching slag

[0178]

[0179] Note: ND means not detected and blank means no standard limit.

[0180] The prepared stabilizing agent Examples 1-9 and Comparative Examples 1-26 (GH-1 to GH-35) were mixed with zinc smelting leaching slag at a 10% addition ratio (mass fraction), and then 20% of water was added to the total mass fraction after the mixture, stirred and mixed evenly, and then cured for 15 days to obtain stabilized leaching slag.

[0181] The soluble metal contents of Zn, Cd, Pb and Mn in the leached residue before and after stabilization were tested, and the stabilization effect of the soluble heavy metal leaching toxicity (HJ / T 299) of Zn, Cd, Pb and Mn was tested, such as Figure 2-Figure 5 shown.

[0182] Depend on Figure 2 From the experimental results, it can be seen that the stabilization rates of Zn by 15 composite agents, including GH-3, GH-5, GH-6, GH-7, GH-9, GH-13, GH-14, GH-15, GH-18, GH-21, GH-24, GH-26, GH-27, GH-28, and GH-29, are all over 95%, and the stabilization effect is outstanding; although the leaching concentration of Zn in the leaching residue is the highest, since Zn is a type of heavy metal that is easier to stabilize among the four heavy metals, the stabilization effect of the stabilizing agent on Zn is the best.

[0183] Depend on Figure 3 It can be seen from the experimental results that the stabilization rate of Cd by 10 composite agents, including GH-3, GH-5, GH-6, GH-7, GH-9, GH-13, GH-14, GH-15, GH-27 and GH-29, exceeds 90%, and the stabilization effect is significant.

[0184] Depend on Figure 4 It can be seen from the experimental results that the stabilization rates of Pb by 12 composite agents, including GH-3, GH-5, GH-6, GH-7, GH-13, GH-14, GH-15, GH-24, GH-26, GH-27, GH-28, and GH-29, are all over 70%, and the stabilization effect is good; GH-5 and GH-14 have the highest stabilization rates for Pb, which are 95.80% and 90.69% respectively.

[0185] Depend on Figure 5 It can be seen from the experimental results that the stabilization rates of Mn by 11 composite agents, including GH-3, GH-5, GH-6, GH-7, GH-9, GH-13, GH-14, GH-15, GH-26, GH-27 and GH-29, are all over 75%, among which the stabilization rates of Mn by GH-5, GH-13, GH-14 and GH-15 are 95.73%, 96.89%, 99.31% and 94.62% respectively. Mn is the most difficult heavy metal to stabilize in the leaching residue.

[0186] Based on the above experimental results, the stabilizers GH-3, GH-5, GH-6, GH-7, GH-13, GH-14, GH-15, GH-27, and GH-29 prepared in Examples 1-9 of the present invention have good synchronous stabilization effects on soluble Zn, Cd, Pb, and Mn in high leaching toxicity leaching residues. The stabilizers GH-1, GH-4, GH-8, GH-9, GH-12, GH-18, GH-21, GH-24, GH-26, GH-28, and GH-25 prepared in Comparative Examples 1-11 also have good synchronous stabilization effects on soluble Zn, Cd, Pb, and Mn in high inlet and outlet toxicity leaching residues, but their stabilization effects are still somewhat different from those of the embodiments. The results show that the embodiments of modifying kaolin can effectively improve the adsorption capacity of kaolin and improve the adsorption and stabilization capacity of the stabilizer for soluble heavy metals Zn, Cd, Pb, and Mn. According to the test results of the stabilized agents prepared in Comparative Examples 12-18, the stabilization ability of the stabilized agent prepared with only a single base material is weaker, or it can only effectively stabilize one or two heavy metals, and does not have the ability to adsorb and stabilize soluble heavy metals Zn, Cd, Pb, and Mn at the same time. The results show that the addition of oyster shell powder can form a synergistic effect with modified kaolin, expanding the application range of the stabilized agent for adsorption of soluble heavy metals. According to the test results of the stabilized agents prepared in Comparative Examples 19-21, the heavy metal stabilization ability of the stabilized agent prepared without adding the main calcium-containing auxiliary material is further reduced, and it has almost no effect on reducing the toxicity of all heavy metals. According to the test results of the stabilizing agents prepared in Comparative Examples 22-26, it can be seen that the stabilizing agents prepared by adding only a single base material kaolin and a variety of calcium-containing main auxiliary materials have the opposite effect on the stabilization of heavy metals. This is mainly because when a variety of calcium-containing main auxiliary materials coexist with kaolin, coupling competition will occur, such as adsorption competition and ion exchange interference, which weakens their respective passivation effects on heavy metals.

[0187] The stabilization effect of modified kaolin, sepiolite, potassium hydrogen phosphate, struvite, silicon fertilizer, oyster shell powder, carbide slag, calcium oxide, calcium hydroxide and other basic agents at different addition ratios (mass fraction) of 1%, 3%, 5%, 8%, 10% and 15% on the soluble heavy metal leaching toxicity (HJ / T 299) of Zn, Cd, Pb and Mn in zinc smelting leaching slag is as follows Figure 6-Figure 7The results show that when the above basic reagents are used alone, a good stabilization effect can be achieved for the soluble heavy metals Zn, Cd, Pb, and Mn in the zinc smelting leaching slag at a higher addition ratio, and the maximum reduction rate of leaching toxicity is above 90%. However, compared with the embodiment of the present invention, the amount of reagent added is higher, the stabilization efficiency is lower under the same addition amount, and the simultaneous stabilization effect of the four heavy metals is poor, especially the stabilization effect of heavy metals such as Mn and Pb is poor.

[0188] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A simultaneous stabilization agent for soluble heavy metals in solid waste, characterized in that: The composition comprises the following components in parts by weight: 30-60 parts of base material, 20-30 parts of main auxiliary materials and 20-50 parts of secondary auxiliary materials; Among them, the base materials are modified kaolin and oyster shell powder, the main auxiliary materials are any one of carbide slag, calcium hydroxide and calcium oxide, and the secondary auxiliary materials are at least two of sepiolite, potassium hydrogen phosphate, struvite, wollastonite and silicon fertilizer.

2. The simultaneous stabilization agent for soluble heavy metals in solid waste according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 40-50 parts of base material, 20-30 parts of main auxiliary material and 30-40 parts of secondary auxiliary material.

3. The agent for simultaneous stabilization of soluble heavy metals in solid waste according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 45 parts of base material, 20 parts of main auxiliary materials and 35 parts of secondary auxiliary materials.

4. The agent for simultaneous stabilization of soluble heavy metals in solid waste according to any one of claims 1 to 3, characterized in that: The mass ratio of modified kaolin and oyster shell powder in the base material is (3-6): (2-5).

5. The agent for simultaneous stabilization of soluble heavy metals in solid waste according to claim 1, characterized in that: The modified kaolin is prepared by the following method: kaolin is calcined at high temperature and then cooled.

6. The agent for simultaneous stabilization of soluble heavy metals in solid waste according to claim 5, characterized in that: The high temperature sintering conditions are: heating to 1200-1400° C. at a heating rate of 5-10° C. / min and keeping the temperature for 2-3 hours.

7. The method for preparing the simultaneous stabilization agent for soluble heavy metals in solid waste according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: grinding the raw materials, drying them, and then mixing them evenly to obtain the product.

8. The method for preparing a simultaneous stabilization agent for soluble heavy metals in solid waste according to claim 7, characterized in that: After grinding, the raw materials are sieved through 100-200 mesh and dried to a moisture content of ≤3%.

9. Use of the simultaneous stabilization agent for soluble heavy metals in solid wastes according to any one of claims 1 to 6 in reducing the content of heavy metals Zn, Cd, Pb and Mn in solid wastes.

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