Multifunctional soil conditioner based on lead-zinc tailings and preparation method and application thereof

Abstract

The application discloses a multifunctional soil conditioner based on lead-zinc tailings and a preparation method and application thereof, and the preparation method comprises the following steps: mixing lead-zinc tailings with calcium-containing minerals, silicon-containing minerals, aluminum-containing minerals and magnesium-containing minerals according to the element proportion of target water-soluble and / or citric-soluble minerals, and adding carbon-containing substances to mix and grind to obtain raw materials; the raw materials are calcined to obtain solids and flue gas, wherein the flue gas is used for lead-zinc recovery after being cooled and collected, and the solids are cooled to obtain clinkers; the clinkers and functional accessories are mixed, ground into powder to obtain a powder-like multifunctional soil conditioner; or the powder-like multifunctional soil conditioner is formed into a granular multifunctional soil conditioner through a forming process. The soil conditioner has the advantages of neutralizing acidic soil, fixing heavy metals in soil and supplementing nutrient components required by soil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bulk, safe and high-value comprehensive utilization of lead-zinc tailings, and in particular to a multifunctional soil conditioner based on lead-zinc tailings, a preparation method and application thereof. BACKGROUND

[0002] In recent years, a large amount of work has been done on the development of lead-zinc tailings in China. Researches such as re-election of valuable metals, preparation of building materials, use in mine filling and mine environment restoration have been carried out, and certain results have been achieved. However, these works still have a lot of deficiencies, and the effect is not good enough. The real substantive problems of lead-zinc tailings have not been solved. For example, the composition of lead-zinc tailings is complex, the particle size is small, and the degree of argillization is high. It is difficult to recover valuable metals by re-election, and the amount of tailings is not reduced. Although lead-zinc tailings can be used as raw materials to produce cement, bricks, boards, ceramics, microcrystalline glass and other building materials, the high impurities in the raw materials lead to poor product performance and poor efficiency, which is difficult to continue under the overall downward background of the current building materials industry. Although lead-zinc tailings can be used for mine filling or mine reclamation, the heavy metal ions contained therein are easy to migrate with surface water and groundwater, causing regional environmental pollution.

[0003] In lead-zinc tailings, in addition to a small amount of heavy metal elements such as lead and zinc, the vast majority are non-metal vein gangue minerals, including quartz, calcite, dolomite and the like, and the main constituent elements are Ca, Si, Al, Mg, Fe and the like. However, these minerals are insoluble, and these elements cannot be used in soil conditioners. SUMMARY

[0004] In view of the above-mentioned deficiencies existing at present, the present application provides a multifunctional soil conditioner based on lead-zinc tailings and a preparation method thereof. The present application firstly targets the generation of water-soluble and / or citric-soluble alkaline minerals such as wollastonite, calcium melilite, calcium-magnesium feldspar, nepheline, etc. based on the mineral composition and element composition of lead-zinc tailings, and then adds various calcium-containing, silicon-containing and aluminum-containing minerals to regulate the composition ratio of SiO2, CaO, Al2O3 and MgO in raw materials to meet the generation requirements of target minerals. Carbon-containing substances are introduced into the ingredients of the present application, and the reduction of lead, zinc and other compounds in lead-zinc tailings at high temperature is utilized to make them volatilize with flue gas, which not only reduces the content of heavy metals in the soil conditioner to below the safety threshold, but also realizes the recovery of heavy metals. The present application obtains smoke dust rich in lead and zinc by cooling, and can obtain lead and zinc products after collection and processing. The present application further improves the functionality and applicability of the soil conditioner by compounding the calcined clinker, and a small amount of fertilizer and functional materials are compounded into the clinker according to the properties and improvement requirements of the application object to obtain a multifunctional soil conditioner, so as to realize the targeted development and individual customization of the product. The preparation method of the soil conditioner of the present application is considerate, feasible and low in cost, which not only realizes the recovery of lead and zinc metals in tailings, but also produces multifunctional soil conditioners with good performance and wide application. The present application helps to realize the large-scale, safe and high-value disposal of lead-zinc tailings, and provides high-quality multifunctional soil conditioners for the improvement of acid soil and heavy metal contaminated soil in China.

[0005] In order to achieve the above-mentioned purposes, the present application provides a preparation method of a multifunctional soil conditioner based on lead-zinc tailings, comprising the following steps:

[0006] S1, mixing lead-zinc tailings with calcium-containing minerals, silicon-containing minerals, aluminum-containing minerals and magnesium-containing minerals according to the element ratio of target water-soluble and / or citric-soluble minerals, and adding carbon-containing substances for mixing and grinding to obtain raw materials;

[0007] S2, calcining the raw materials to obtain solids and flue gas; wherein the flue gas is cooled and collected, and then lead and zinc are recovered (the tail gas is treated by absorption and purification to meet the emission standard); and the solids are cooled to obtain clinker;

[0008] S3, mixing the clinker and functional auxiliary materials in proportion, grinding into powder to obtain a multifunctional soil conditioner in powder form; or forming a multifunctional soil conditioner in granular form by a forming process.

[0009] The mechanism of the present application is as follows:

[0010] The lead-zinc tailings of the present application mainly contain non-metallic minerals such as quartz and calcite. In the lead-zinc tailings batching high-temperature calcination system, the thermal decomposition reaction of calcite (CaCO3) in the lead-zinc tailings is the beginning of the mineral phase reconstruction process in the whole process. First, the thermal decomposition of calcite will form calcium oxide (CaO), which will then react with various additives added at high temperature. Specifically:

[0011] When the batching contains potassium feldspar, the lattice vibration energy induced by high-temperature conditions (above 1100℃) can break the bonding energy threshold of the Si-O-Al bond of potassium feldspar, causing the phase change decomposition of potassium feldspar to generate leucite and liquid SiO2 (Formula 1). This process is reversible, and during this period, CaO breaks the phase balance of the silicate system, promoting the directional mineralization reaction of liquid SiO2 and CaO to generate wollastonite (Formula 2). The generation of wollastonite not only consumes liquid SiO2 to reduce the viscosity of the system, but also drives the reaction equilibrium to continuously move to the right, forming a typical "calcium-silicate melt-new crystal phase" coupling reaction mechanism, which promotes the further decomposition of leucite into soluble potash feldspar.

[0012] When the batching contains potassium feldspar and gypsum, there is a certain synergistic effect between gypsum and calcium oxide. On the one hand, calcium oxide reacts with feldspar to generate potash feldspar and wollastonite through the chain reaction of Formula 1-Formula 2 during calcination. On the other hand, the lattice of CaSO4 in gypsum relaxes under high-temperature conditions, reducing the activation energy of Ca 2+ , based on the Wagner ion diffusion theory, the activation energy of Ca 2+ in gypsum is significantly higher than the migration energy barrier of K + in feldspar / leucite lattice, forming a concentration gradient-driven cross-crystal phase cation exchange, and the preferential migration of Ca 2+ causes the interlayer charge reconstruction of the feldspar lattice to generate soluble potassium sulfate and calcium hellewing.

[0013] When the batching contains brucite, its thermal decomposition forms magnesium oxide. Under high-temperature conditions, magnesium oxide reacts with the decomposition products of quartz and calcite in the tailings to form soluble calcium-magnesium feldspar (Formula 4), providing soluble calcium, magnesium, and silicon for soil conditioners.

[0014] According to the phase diagrams of SiO2-Al2O3-CaO, SiO2-CaO-MgO, KAlSi3O8-SiO2, etc., the proportion range of SiO2, Al2O3, CaO, MgO, etc. required for generating water-soluble and citric-soluble alkaline minerals such as wollastonite, calcium melilite, calcium-magnesium feldspar, nepheline, etc. can be calculated; and according to the fitting of the ΔG values of each main reaction at different temperatures, the generation temperature range of target phases such as potassium nepheline, wollastonite, calcium melilite, and magnesium melilite is determined. Accordingly, different ingredients can be accurately introduced according to the mineral composition and chemical composition of the tailings, and the calcination temperature is determined. The quantitative conversion from mineral composition analysis to ingredient design is realized.

[0015] The innovation of the reaction mechanism lies in breaking through the traditional empirical ingredient mode in the process of tailings pyroprocessing, and breaking the limitation that a suitable formula must be found through a large number of experiments; instead, a design-type technical path of “product mineral phase target orientation-thermodynamic driving regulation” is constructed, realizing the combination-type innovation of theory and technology from mineral microstructure regulation to macroscopic reaction process control, and providing a universal method and technology for high-value utilization of lead-zinc tailings.

[0016]

[0017] SiO2+CaO=CaSiO3 Formula 2

[0018] 2KAlSi3O8+8CaSO4+2CaO=KAlSiO4+K2SO4+Ca2Al2SiO7+6CaSiO3+7SO2+3.5O2+Ca2SiO4 Formula 3

[0019] MgO+2CaO+2SiO2=Ca2MgSi2O7 Formula 4

[0020] According to one aspect of the present application, in step S1, the carbon-containing substance includes any one or more of coal, biomass, coke, charcoal, graphite, and stone coal, and the addition amount of the carbon-containing substance accounts for 0.5-5wt% of the raw material.

[0021] It should be noted that the carbon-containing substance is used as a reducing agent to reduce lead and zinc in the tailings at high temperature in the calcination process. After combustion of the carbon-containing substance, a small amount of ash is generated, which also contains SiO2, Al2O3, CaO, MgO, etc., but the total amount is very small, so the influence on the chemical composition of the clinker can be ignored.

[0022] According to one aspect of the present application, in step S1, the calcium-containing mineral includes any one or more of calcite, limestone, marble, dolomite, gypsum, apatite, and wollastonite; the silicon-containing mineral includes any one or more of quartz, feldspar, wollastonite, mica, talc, and kaolinite; the aluminum-containing mineral includes any one or more of bauxite, feldspar, kaolinite, and mica; and the magnesium-containing mineral includes any one or more of magnesite, brucite, dolomite, talc, and serpentine.

[0023] According to one aspect of the present application, in step S1, the water-soluble mineral and / or the citric acid-soluble mineral includes wollastonite, calcium melilite, calcium-magnesium feldspar, and nepheline; and in step S2, the SiO2 content of the clinker is 25-50%, the CaO content is 30-50%, the Al2O3 content is 1-8%, the MgO content is 1-8%, the SiO2+CaO content is 75-85%, and the SiO2+CaO+Al2O3+MgO content is 80-95%.

[0024] According to one aspect of the present application, in step S2, the calcination temperature is 1100-1300℃, and the calcination time is 60-240 min.

[0025] According to one aspect of the present application, in step S3, the functional auxiliary material includes any one or more of a fertilizer and a functional material; and the addition amount of the functional auxiliary material is not more than 10% by weight of the clinker.

[0026] According to one aspect of the present application, the fertilizer includes any one or more of a nitrogen-phosphorus-potassium fertilizer, an organic fertilizer, and a trace element fertilizer.

[0027] According to one aspect of the present application, the functional material includes any one or more of a heavy metal solidifying agent, a water-retaining agent, a porous material, and a microbial agent.

[0028] Based on the same inventive concept, the present application also provides a multifunctional soil conditioner prepared by the above preparation method.

[0029] Based on the same inventive concept, the present application also provides the use of the above multifunctional soil conditioner in acid soil and / or heavy metal contaminated soil.

[0030] The present application has the following advantages:

[0031] (1) The present application completely solves the problems of difficult recovery of lead and zinc resources and easy pollution in the traditional comprehensive utilization process of lead and zinc tailings, and insufficient utilization of non-metallic minerals, and the obtained soil conditioner product has a wider market and higher added value, and truly realizes the resource utilization of massification, safety, and high value of lead and zinc tailings.

[0032] (2) The invention takes wollastonite, calcium yellow long stone, calcium magnesium long stone, nepheline and other water-soluble minerals and / or carbon-soluble minerals as the target product of high-temperature mineral phase reconstruction, and constructs a batching scheme based on lead-zinc tailings as a guide, so that the selectivity of the batching raw materials is wider, the batching addition ratio is more reasonable, and the components and properties of the product are fully guaranteed.

[0033] (3) The invention adds carbon-containing substances to the batching, as a reducing agent for the high-temperature process, and through optimization of the calcination process, the lead, zinc and other heavy metals in the lead-zinc tailings can be fully reduced and volatilized, and combined with the deep treatment of flue gas and tail gas, the valuable metal resources in the lead-zinc tailings are fully recovered and utilized, and there is no heavy metal residue in the clinker, so that a safe and standard soil conditioner is made.

[0034] (4) Taking the clinker fired by the lead-zinc tailings as the main component, a small amount of fertilizer and functional materials are compounded into the clinker to obtain a multifunctional soil conditioner, so that the targeted development and personalized customization of the product are realized. This further improves the functionality and applicability of the soil conditioner product, and better meets the nature and improvement target requirements of the application soil object itself.

[0035] In summary, the patent prepares the multifunctional soil conditioner from the lead-zinc tailings through scientific proportioning and complete process, and simultaneously realizes the recovery of the valuable metals such as lead and zinc in the tailings. The process flow of the technology is simple, the batching is easy to obtain, the mineral components in the tailings are fully utilized, the soil conditioner product is safe and the performance is controllable, the heavy metals in the tailings can be fully recovered, which provides a new idea for the bulk, safety and high-value utilization of lead-zinc tailings in China, and provides strong help for the improvement of acid soil and heavy metal contaminated soil in China. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The process flow chart of the preparation method of the multifunctional soil conditioner based on lead-zinc tailings according to the invention. DETAILED DESCRIPTION

[0037] In order to make the invention easier to understand, the invention will be further described below in combination with specific examples. It should be understood that these examples are only used to illustrate the invention and not to limit the scope of the invention. Obviously, the described examples are only a part of the examples of the invention, not all the examples. Based on the examples in the invention, all other examples obtained by those skilled in the art without creative labor belong to the scope of protection of the invention. Unless otherwise defined, the professional terms used below are consistent with the meanings understood by those skilled in the art; unless otherwise specified, the raw materials and reagents involved in this paper can be purchased from the market or prepared by known methods.

[0038] In order to solve the problem that the existing lead-zinc tailings are difficult to utilize, the inventors provide a preparation method of a multifunctional soil conditioner based on lead-zinc tailings, a process flow chart of which is shown in Figure 1 as follows:

[0039] S1, mix the lead-zinc tailings with calcium-containing minerals, silicon-containing minerals, aluminum-containing minerals, magnesium-containing minerals and carbon-containing substances, and then grind to obtain raw materials; wherein the lead-zinc tailings, calcium-containing minerals, silicon-containing minerals, aluminum-containing minerals and magnesium-containing minerals are mixed according to the element ratio of target water-soluble minerals and / or citric-soluble minerals; preferably, the carbon-containing substances include any one or more of coal, biomass, coke, charcoal, graphite, stone coal and combustible organic matter; the addition amount of the carbon-containing substances is 0.5-5wt% of the raw materials. Preferably, the calcium-containing minerals include any one or more of calcite, limestone, marble, dolomite, gypsum, apatite and wollastonite; the silicon-containing minerals include any one or more of quartz, feldspar, wollastonite, mica, talc, kaolinite and montmorillonite; the aluminum-containing minerals include any one or more of bauxite, feldspar, kaolinite and montmorillonite; the magnesium-containing minerals include any one or more of magnesite, brucite, dolomite, talc and serpentine. Preferably, the water-soluble minerals and / or citric-soluble minerals include wollastonite, calcium yellow long stone, calcium magnesium long stone and nepheline.

[0040] S2, calcine the raw materials to obtain solids and flue gas; wherein the flue gas is cooled and collected, and then subjected to lead-zinc recovery (the tail gas is treated by absorption purification and then discharged according to the standard); the solids are cooled to obtain clinker. Preferably, the calcination temperature is 1100-1300℃, and the calcination time is 60-240min. Preferably, the SiO2 content in the clinker is 25-50%, the CaO content is 30-50%, the Al2O3 content is 1-8%, the MgO content is 1-8%, the SiO2+CaO content is 75-85%, and the SiO2+CaO+Al2O3+MgO content is 80-95%.

[0041] S3, mix the clinker and functional additives in proportion, grind to powder to obtain a powder multifunctional soil conditioner; or form the powder multifunctional soil conditioner into granular multifunctional soil conditioner by a molding process. Preferably, the functional additives include any one or more of fertilizers and functional materials; the addition amount of the functional additives is not more than 10wt% of the clinker. Preferably, the fertilizers include any one or more of nitrogen, phosphorus and potassium fertilizers, organic fertilizers and trace element fertilizers. Preferably, the functional materials include any one or more of heavy metal solidifying agents, water-retaining agents, porous materials and microbial agents.

[0042] The application will be further described in conjunction with specific examples and comparative examples.

[0043] Example 1

[0044] The mineral composition of the lead-zinc tailings in this example is mainly quartz, calcite, etc., and the chemical composition is shown in Table 1.

[0045] Table 1 Chemical composition of lead-zinc tailings in Example 1 (%)

[0046] SiO2 Al2O3 Na2O K2O CaO MgO 22.827 2.40 0.74 0.676 35.8 0.81 Fe2O3 ZnO PbO BaO SO3 LOI 6.103 1.446 0.505 0.635 1.402 26.653

[0047] (1) White dolomite (calcium-containing mineral, magnesium-containing mineral), quartz (silicon-containing mineral), potassium feldspar (aluminum-containing mineral, silicon-containing mineral), and magnesite (magnesium-containing mineral) were used as ingredients, which were mixed with the lead-zinc tailings in calculated amounts. Then 98.2 g of the mixture was mixed with 1.8 g of coal and ground to obtain raw material;

[0048] (2) The raw material was placed in a tube furnace and calcined at 1180°C for 120 minutes. During calcination, a flue gas cooling bottle and an exhaust gas absorption bottle were connected to the back of the tube furnace, respectively. After calcination, the powder in the cooling bottle was recovered to obtain lead-zinc-rich dust; the SiO2 content in the prepared clinker was 31.7%, the CaO content was 46.7%, the Al2O3 content was 3.1%, the MgO content was 6.4%, the SiO2+CaO content was 78.4%, and the SiO2+CaO+Al2O3+MgO content was 87.9%;

[0049] (3) The calcined clinker was taken out, 8wt% humic acid was added and mixed uniformly, then extruded into short strips to obtain alkaline humic acid soil conditioner meeting the requirements of HG / T 5782-2020 standard.

[0050] Example 2

[0051] The mineral composition of the lead-zinc tailings in this example is mainly quartz, calcite, etc., and the chemical composition is shown in Table 2.

[0052] Table 2 Chemical composition of lead-zinc tailings in Example 2 (%)

[0053] SiO2 Al2O3 Na2O K2O CaO MgO 40.434 4.46 0.39 0.983 24.793 0.658 Fe2O3 ZnO PbO BaO SO3 LOI 2.503 0.81 0.148 0.131 4.107 20.588

[0054] (1) Gypsum (calcium-containing mineral), apatite (calcium-containing mineral), potassium feldspar (aluminum-containing mineral, silicon-containing mineral), and brucite (magnesium-containing mineral) were used as ingredients, which were mixed with the lead-zinc tailings in calculated amounts, and then 98.6 g of the mixture was mixed with 1.4 g of charcoal and ground to obtain raw material;

[0055] (2) Put the raw material into a tube furnace and calcine at 1200°C for 90 minutes. During the calcination process, a flue gas cooling bottle and an exhaust gas absorption bottle are connected to the back of the tube furnace, respectively. After the calcination is completed, the powder in the cooling bottle is recovered to obtain flue dust rich in lead and zinc; the SiO2 content in the prepared clinker is 43.5%, the CaO content is 37.7%, the Al2O3 content is 4.8%, the MgO content is 3.4%, the SiO2+CaO content is 81.2%, and the SiO2+CaO+Al2O3+MgO content is 89.4%.

[0056] (3) Take out the calcined clinker, add 7wt% of potassium dihydrogen phosphate to it, mix uniformly, and granulate into balls to obtain an alkaline inorganic compound soil conditioner that meets the requirements of DB44 / T 1598-2015 standard.

[0057] Example 3

[0058] The mineral composition of the lead-zinc tailings in this example is mainly quartz, calcite, etc., and the chemical composition is shown in Table 3.

[0059] Table 3 Chemical composition of lead-zinc tailings in Example 3 (%)

[0060] SiO2 Al2O3 Na2O [K2O] CaO MgO 27.36 2.62 0.42 0.607 33.01 0.414 Fe2O3 ZnO PbO BaO SO3 LOI 7.316 1.06 0.46 0.337 2.067 24.329

[0061] (1) White dolomite (calcium-containing mineral, magnesium-containing mineral), apatite (calcium-containing mineral), phosphogypsum (calcium-containing mineral), and potassium feldspar (aluminum-containing mineral, silicon-containing mineral) are used as raw materials, which are mixed with the lead-zinc tailings according to the calculated amount, and then 97.9g of the mixture is uniformly mixed with 2.1g of biomass to obtain a raw material;

[0062] (2) Put the raw material into a tube furnace and calcine at 1250°C for 100 minutes. During the calcination process, a flue gas cooling bottle and an exhaust gas absorption bottle are connected to the back of the tube furnace, respectively. After the calcination is completed, the powder in the cooling bottle is recovered to obtain flue dust rich in lead and zinc; the SiO2 content in the prepared clinker is 30.7%, the CaO content is 45.9%, the Al2O3 content is 2.9%, the MgO content is 4.2%, the SiO2+CaO content is 76.6%, and the SiO2+CaO+Al2O3+MgO content is 83.7%.

[0063] (3) Take out the calcined clinker, add 5wt% of urea and 5wt% of potassium dihydrogen phosphate to it, mix uniformly, and granulate into balls to obtain an alkaline soil conditioner that meets the requirements of T / HNPCIA 11-2019 standard.

[0064] Example 4

[0065] The mineral composition of the lead-zinc tailings in this example is mainly quartz, calcite, etc., and the chemical composition is shown in Table 4.

[0066] Table 4 Chemical composition of lead-zinc tailings of Example 3 (%)

[0067] SiO2 Al2O3 Na2O K2O CaO MgO 38.98 3.54 0.76 0.983 28.21 0.617 Fe2O3 ZnO PbO BaO SO3 LOI 4.575 1.09 0.37 0.112 1.203 19.560

[0068] (1) Quartz (silicon-containing mineral), potassium feldspar (aluminum-containing mineral, silicon-containing mineral), bauxite (aluminum-containing mineral), dolomite (calcium-containing mineral, magnesium-containing mineral), gypsum (calcium-containing mineral) were used as ingredients, and they were mixed with the lead-zinc tailings in a calculated amount, and then 95 g of the mixture was uniformly mixed with 5 g of coal powder and ground to obtain raw material;

[0069] (2) The raw material B was calcined in a tube furnace at 1200 °C for 120 minutes. During the calcination process, a flue gas cooling bottle and an exhaust gas absorption bottle were connected to the back of the tube furnace, respectively. After the calcination was completed, the powder in the cooling bottle was recovered to obtain lead-zinc-rich dust; the SiO2 content in the prepared clinker was 40.4%, the CaO content was 38.5%, the Al2O3 content was 7.2%, the MgO content was 2.1%, the SiO2+CaO content was 78.9%, and the SiO2+CaO+Al2O3+MgO content was 88.2%.

[0070] (3) The calcined clinker was taken out, 4wt% of magnesium chloride and 4wt% of potassium chloride were added thereto, and after being uniformly mixed, a silicon-calcium-potassium-magnesium fertilizer soil conditioner meeting the requirements of GB / T 36207-2018 standard was obtained.

[0071] Comparative Example 1

[0072] The difference between this comparative example and Example 1 is that the calcination temperature is 1000 °C, and the other steps and parameters are the same as those of Example 1. The final product obtained belongs to an under-fired state, in which the mass fraction of effective silicon is less than 10%, and it does not meet the requirements of HG / T 5782-2020 standard.

[0073] Comparative Example 2

[0074] The difference between this comparative example and Example 1 is that the calcination temperature is 1350 °C, and the other steps and parameters are the same as those of Example 1. The final product obtained belongs to an over-fired state, in which the mass fraction of effective calcium is less than 15% and the mass fraction of effective magnesium is less than 3%, and it does not meet the requirements of HG / T 5782-2020 standard.

[0075] Comparative Example 3

[0076] The difference between this comparative example and Example 1 is that no carbon-containing substance is added, and the other steps and parameters are the same as those of Example 1. Because of the lack of the reduction effect of the carbon-containing substance during the calcination process, the total lead content in the final product obtained exceeds the harmful element limit requirement by dozens of times, and it does not meet the requirements of HG / T 5782-2020 standard.

[0077] Comparative Example 4

[0078] The difference between the present comparative example and Example 1 is that the SiO2 content in the clinker is 52.6%, the CaO content is 25.8%, and the other steps and parameters are the same as those in Example 1. In the final product, the mass fraction of effective silicon is less than 10%, the mass fraction of effective calcium is less than 15%, and the mass fraction of effective magnesium is less than 3%, which does not meet the standard requirements of HG / T 5782-2020.

[0079] Comparative Example 5

[0080] The difference between the present comparative example and Example 1 is that humic acid is not added, and the other steps and parameters are the same as those in Example 1. In the final product, the mass fraction of total humic acid and the mass fraction of activated humic acid are both 0, which does not meet the standard requirements of HG / T 5782-2020.

[0081] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any skilled person in the art can easily think of changes or replacements within the scope of the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing a multifunctional soil conditioner based on lead-zinc tailings, characterized in that, Includes the following steps: S1. The lead-zinc tailings are mixed with calcium-containing minerals, silicon-containing minerals, aluminum-containing minerals, and magnesium-containing minerals according to the elemental ratio of the target water-soluble and / or citric acid-soluble minerals, and carbon-containing materials are added and ground to obtain raw materials; wherein, the carbon-containing materials include any one or more of coal, biomass, coke, charcoal, graphite, and coal shale; the calcium-containing minerals include any one or more of calcite, limestone, marble, dolomite, gypsum, apatite, and wollastonite; the silicon-containing minerals include any one or more of quartz, feldspar, wollastonite, mica, talc, kaolinite, and montmorillonite; the aluminum-containing minerals include any one or more of bauxite, feldspar, kaolinite, montmorillonite, and mica; and the magnesium-containing minerals include any one or more of magnesite, brucite, dolomite, talc, and serpentine. S2. The raw materials are calcined to obtain solids and flue gas; wherein the flue gas is cooled, collected, and then used for lead and zinc recovery; the solids are cooled to obtain clinker. S3. Mix the clinker and functional additives in a certain proportion, grind them into powder, and obtain a powdered multifunctional soil conditioner; or obtain a granular multifunctional soil conditioner from the powdered multifunctional soil conditioner through a molding process.

2. The preparation method of the multifunctional soil conditioner based on lead-zinc tailings according to claim 1, characterized in that, In step S1, the amount of carbon-containing material added accounts for 0.5-5 wt% of the raw material.

3. The preparation method of the multifunctional soil conditioner based on lead-zinc tailings according to claim 1, characterized in that, In step S1, the water-soluble and / or citric acid-soluble minerals include wollastonite, anorthite, calcium magnesium feldspar, and nepheline; in step S2, the clinker contains 25-50% SiO2, 30-50% CaO, 1-8% Al2O3, 1-8% MgO, 75-85% SiO2+CaO, and 80-95% SiO2+CaO+Al2O3+MgO.

4. The preparation method of the multifunctional soil conditioner based on lead-zinc tailings according to claim 1, characterized in that, In step S2, the calcination temperature is 1100-1300 ℃, and the calcination time is 60-240 min.

5. The preparation method of the multifunctional soil conditioner based on lead-zinc tailings according to claim 1, characterized in that, In step S3, the functional additives include any one or more of fertilizers and functional materials; the amount of the functional additives added does not exceed 10 wt% of the clinker.

6. The preparation method of the multifunctional soil conditioner based on lead-zinc tailings according to claim 5, characterized in that, The fertilizer includes any one or more of nitrogen, phosphorus, and potassium fertilizers, organic fertilizers, and micronutrient fertilizers.

7. The preparation method of the multifunctional soil conditioner based on lead-zinc tailings according to claim 5, characterized in that, The functional materials include any one or more of the following: heavy metal curing agents, water-retaining agents, porous materials, and microbial agents.

8. A multifunctional soil conditioner, characterized in that, It is prepared by any of the preparation methods described in claims 1-7.

9. The application of the multifunctional soil conditioner according to claim 8 in acidic soil and / or heavy metal contaminated soil.

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