Phosphogypsum harmless agent and engineering application method

Abstract

A phosphogypsum harmless agent and an engineering application method therefor. The agent is composed of a powder component and a liquid component, wherein the powder component is composed of an alkaline component and talcum powder, the alkaline component being at least one of calcium oxide, magnesium oxide, calcium hydroxide and magnesium hydroxide; and the liquid component is an aqueous solution of at least one of a soluble ferric salt, aluminum salt and calcium salt. The engineering application method therefor comprises: S1, crushing and sieving phosphogypsum until the particle size is 1-5 mm, while adjusting the moisture content of attached water to 5-10%; S2, uniformly mixing the phosphogypsum with a powder component; S3, adding a liquid component, and adjusting the moisture content of attached water to 12-20%; and S4, maintaining same for test. In the agent, multiple components are compounded and divided into a powder component and a liquid component, so as to fully utilize the synergistic effect of the components; the mixing is performed by adding the powder agent and the liquid-phase agent stepwise, thereby adjusting the water content stepwise, regulating and controlling the mixing uniformity, controlling flying dust during the engineering implementation process, and achieving more environmentally friendly and more efficient engineering application.

Description

A harmless agent for phosphogypsum and engineering application method Technical Field

[0001] The present invention belongs to the field of solid waste treatment and disposal, and particularly relates to a phosphogypsum harmless agent and an engineering application method. Background Art

[0002] Phosphoric acid, a primary product of the phosphorus chemical industry, is a key raw material for phosphate fertilizers and power batteries such as lithium iron phosphate, and is crucial to national food and energy security. The main processes for phosphoric acid production include wet processing and pyrometallurgical processing. The wet processing method is currently the mainstream production process, with costs approximately one-quarter lower than the pyrometallurgical process. However, the wet processing of phosphoric acid produces a large amount of phosphogypsum as a byproduct. According to statistics, the production of one ton of phosphoric acid generates approximately 4-5 tons of phosphogypsum. Currently, 250-280 million tons of phosphogypsum are stored in slag yards in my country. In addition, approximately 70 million tons of phosphogypsum are newly discharged annually. Phosphogypsum is primarily composed of calcium sulfate dihydrate, but also contains impurities such as Al, Fe, Mg, Si, and Ca, as well as pollutants such as phosphorus, fluorine, and heavy metals.

[0003] At present, the main treatment method for phosphogypsum in my country is stacking. Because it contains a large amount of easily migratable soluble phosphorus and fluorine, acidic insoluble matter, and heavy metals, these harmful substances are constantly transformed and migrated during the stacking process of phosphogypsum, causing long-term pollution to the phosphogypsum storage area and the surrounding environment.

[0004] Besides storage, current methods for utilizing phosphogypsum include making building materials, using it as a cement retarder, and producing sulfuric acid. However, due to high costs, inconsistent product quality, and limited sales volume due to transportation costs, these methods can only absorb a small amount of phosphogypsum and fail to fundamentally address the low phosphogypsum utilization rate. One approach to achieving large-scale phosphogypsum utilization is to dispose of phosphogypsum harmlessly and use it as an engineering material for land remediation, backfilling abandoned mines, and filling underground goafs.

[0005] The use of phosphogypsum as the above-mentioned engineering material needs to meet the requirements of environmental protection. According to the requirements of existing environmental protection technical standards, the content of phosphorus, fluorine and heavy metals in phosphogypsum usually cannot meet the standard limit requirements and needs to be harmlessly treated before use. At present, the harmless treatment methods of phosphogypsum include high-temperature calcination, water washing and chemical passivation technologies. Among them, the high-temperature calcination method consumes a lot of heat, has high energy consumption costs and emits a large amount of carbon dioxide. It is inconsistent with the carbon reduction policy strongly advocated by the country at this stage and has no engineering application prospects. The water washing method consumes a lot of water. After water washing, a large amount of highly polluted wastewater is generated that needs to be treated and discharged. There are problems such as high cost, large consumption of water resources, and limited discharge channels. It has only been used on a small scale in the field of preparing high-value-added building materials from phosphogypsum.

[0006] Chemical passivation technology, by adding a passivating agent to phosphogypsum, converts easily migrating pollutants into less migrating substances, rendering the phosphogypsum harmless. This detoxification significantly expands the application of the treated phosphogypsum. However, the large-scale application of this technology is limited by the lack of efficient passivation agents, the difficulty of controlling dust during implementation, the immature solid-solid mixing process at low dosing ratios, and insufficient mixing.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a harmless agent for phosphogypsum and an engineering application method, so as to at least solve one of the problems existing in the prior art, such as the lack of efficient passivation agents, the difficulty in controlling dust during the implementation process, the immaturity of the solid-solid mixing process at a low addition ratio, and insufficient mixing.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A harmless agent for phosphogypsum, comprising a powder component and a liquid component; wherein:

[0011] The powder component is composed of an alkaline component and talc, and the alkaline component is at least one of calcium oxide, magnesium oxide, calcium hydroxide, and magnesium hydroxide;

[0012] The liquid component is an aqueous solution of at least one of soluble iron salt, aluminum salt and calcium salt.

[0013] In the agent, the alkaline components in the powder components are all alkaline substances, which are used to adjust the acidic phosphogypsum to neutral to weak alkalinity.

[0014] In the agent, talc is selected from the powder component because of its lubricity and hydrophobicity. Its function is to reduce the agglomeration of phosphogypsum and improve its dispersibility by forming a coating film and a hydrophobic layer on the surface of phosphogypsum.

[0015] In this agent, soluble iron salts, aluminum salts and calcium salts are selected as active ingredients in the liquid component because the iron, aluminum and calcium therein can react with phosphate and fluoride ions in phosphogypsum to form stable precipitates. The function is to reduce the mobility of low-soluble substances such as calcium fluoride, calcium phosphate, iron phosphate, aluminum phosphate, etc., and achieve the harmlessness of harmful components such as phosphorus and fluoride.

[0016] Optionally, the soluble aluminum salt includes at least one of aluminum sulfate, aluminum chloride, polyaluminum chloride, etc.

[0017] Optionally, the soluble iron salt includes at least one of ferric sulfate, ferric chloride, ferrous sulfate, polyferric sulfate, etc.

[0018] Optionally, the soluble calcium salt is calcium chloride.

[0019] Among the above components, calcium oxide, magnesium oxide, calcium hydroxide, and magnesium hydroxide are in powder form, and preferably, their particle size differs from the particle size distribution of the phosphogypsum particles to be treated by no more than ±5%, and the content of effective substances is not less than 80%. That is, when a raw material containing calcium oxide, magnesium oxide, calcium hydroxide, and / or magnesium hydroxide is used, the content of calcium oxide, magnesium oxide, calcium hydroxide, and / or magnesium hydroxide in the raw material is not less than 80%.

[0020] Among the above components, talc is in powder form, and the fineness is preferably not less than 400 mesh.

[0021] Among the above components, soluble iron salts, aluminum salts and calcium salts can be selected as industrial grade products, and the pollutant content should meet the requirements of their respective products and be lower than the soil pollutant limit requirements.

[0022] Preferably, in the harmless agent for phosphogypsum, in the powder component, the mass addition ratio of the alkaline component is 0.2% to 1.0%, that is, the mass ratio of the alkaline component to the phosphogypsum to be treated is 0.2% to 1.0% (for example, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, etc.); the mass addition ratio of the talc powder is 0.1% to 0.6%, that is, the mass ratio of the talc powder to the phosphogypsum to be treated is 0.1% to 0.6% (for example, 0.2%, 0.3%, 0.4%, 0.5%, etc.); the mass addition ratio of the liquid component is 0.2-0.6% on a solid basis, that is, the mass ratio of the liquid component on a solid basis to the phosphogypsum to be treated is 0.2-0.6% (for example, 0.25%, 0.30%, 0.40%, 0.50%, 0.55%, etc.).

[0023] Preferably, in the powder component, the mass ratio of the alkaline component to the talc is 2-5:1.

[0024] More preferably, the powder component consists of calcium oxide, magnesium oxide, and talc, with the mass addition ratio being 0.40%, 0.10%, and 0.10%, respectively; the liquid component consists of aluminum sulfate and ferric chloride, with the mass addition ratio being 0.15% and 0.10%, respectively.

[0025] More preferably, the powder component consists of calcium oxide and talc, with the mass addition ratio being 0.48% and 0.12% respectively; the liquid component is polymerized alumina, with the mass addition ratio being 0.40%.

[0026] More preferably, the powder component consists of calcium oxide and talc, with the mass addition ratio being 0.40% and 0.20% respectively; the liquid component consists of polyferric chloride and ferrous sulfate, with the mass addition ratio being 0.10% and 0.20% respectively.

[0027] A method for engineering application of a phosphogypsum harmless agent comprises the following steps:

[0028] S1, phosphogypsum pretreatment: crushing and sieving the phosphogypsum to a particle size of 1-5 mm, and adjusting the adhering water content to 5-10%;

[0029] S2, adding powder components: uniformly mixing the phosphogypsum obtained in step S1 with the powder components in the above-mentioned phosphogypsum harmless agent;

[0030] S3, adding liquid components: adding the liquid components of the above-mentioned phosphogypsum harmless agent to the material obtained in step S2, and adjusting the moisture content of the attached water to 12-20%;

[0031] S4, curing for inspection: the material obtained in step S3 is piled up for inspection, the moisture of the material is maintained to allow it to fully react, and after it meets the standards, it is comprehensively utilized as needed.

[0032] In step S1, if the particle size of phosphogypsum is too large, it may easily lead to uneven raw materials, thereby affecting the harmlessness effect. The smaller the particle size of phosphogypsum, the better, but the processing cost is higher. Taking comprehensive considerations, the particle size of the phosphogypsum after crushing and screening is limited to 1-5mm (for example, 2mm, 3mm, 4mm, etc.); the purpose of adjusting the moisture content is to ensure that the powder can be mixed evenly. The lower the moisture content, the better, but if the requirement is too low, it is easy to increase the processing cost. If the moisture content is too high, it is easy to form lumps and uneven mixing. Taking comprehensive considerations, the moisture content of the attached water is limited to 5-10% (for example, 6%, 7%, 8%, 9%, etc.).

[0033] Optionally, in step S1, the crushing equipment may be a jaw crusher, a cone crusher, a gyratory crusher, a hammer crusher, a roller crusher, an impact crusher, an impact crusher, or the like.

[0034] Optionally, in step S1, the screening equipment may be a fixed screen, a rolling screen, a vibrating screen, etc.

[0035] Optionally, in step S2, the mixing equipment may be continuous or intermittent equipment such as a double-helix conical mixing equipment, a horizontal ribbon mixing equipment, a three-dimensional oscillating mixing equipment, a double-shaft mixing equipment, a concrete mixer, or a pipeline mixer.

[0036] In step S3, it is important to adjust the attached water content of the material to 12-20% (e.g., 13%, 14%, 15%, 16%, 17%, 18%, 19%, etc.); water is a prerequisite for the reaction. If the water content is high, the reaction will be faster. However, if the water content is too high, leachate will be produced, increasing water treatment costs, increasing the risk of secondary pollution and water costs; if the water content is too low, the reaction will be very slow or even non-existent.

[0037] Preferably, in step S3, the liquid component of the phosphogypsum detoxification agent is added by spraying. For example, a spray device can be installed at a suitable location in the discharging area, such as a conveyor belt or a material outlet, of the mixing equipment. During the discharging or transfer of the material obtained in step S2, the liquid component of the phosphogypsum detoxification agent is added to the material, thereby effectively preventing dust.

[0038] Optionally, in step S4, the surface covering material of the material obtained in step S3 is a plastic film, HDPE film, non-woven fabric, plant straw, etc., which can prevent moisture volatilization of the stacked material and provide a good reaction environment.

[0039] Optionally, in step S4, the stacking time is 2-14 days, preferably 3-7 days.

[0040] Compared with the prior art, the solution of the present invention has the following beneficial effects:

[0041] 1. The phosphogypsum harmless agent provided by the present invention compounds multiple components and divides them into powder components and liquid components according to their solubility and compatibility. The agent components include a pH regulating component, a lubricating component and a passivating component. Through the synergistic effect of the three components, the pH regulating performance, lubricating and dispersing performance and high-efficiency passivating performance of the agent are comprehensively utilized to ensure efficient and high-mixing uniformity mixing from the agent.

[0042] 2. The present invention optimizes the reagent adding and mixing process, adds and mixes the powder reagent and the liquid reagent in steps, realizes step-by-step adjustment of moisture content, regulation of mixing uniformity, and control of dust during engineering implementation, realizes more environmentally friendly and more efficient engineering applications, and achieves more efficient passivation of phosphogypsum with a lower reagent addition ratio.

[0043] 3. The solution of the present invention is applied to the harmless treatment of phosphogypsum, which can reduce the dosage ratio of the passivating agent, control the dust during the construction process, and achieve efficient solid-solid mixing with low agent dosage. It is a set of efficient and environmentally friendly phosphogypsum harmless treatment technology system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG1 is a schematic flow chart of an engineering application method of a phosphogypsum harmless agent according to the present invention.

[0045] FIG2 is an SEM image of phosphogypsum before and after the addition of powder and liquid phase reagents in Example 1 of the present invention, wherein A2 is an SEM image of phosphogypsum before the addition of the reagents, and B2 is an SEM image of phosphogypsum after the addition of the reagents.

[0046] Figure 3 is a photo of the mixing and bonding of phosphogypsum with different moisture contents in Example 4 of the present invention, wherein the left picture shows the situation of uniform mixing of phosphogypsum with a low moisture content (9.24%); the middle picture shows the situation of agglomeration after mixing of phosphogypsum with a medium moisture content (19.87%); and the right picture shows the situation of agglomeration and water exudation after mixing of phosphogypsum with a high moisture content (26.32%). DETAILED DESCRIPTION

[0047] FIG1 is a flow chart of a method for applying a phosphogypsum harmless agent engineering according to a preferred embodiment of the present invention, which basically includes the following steps:

[0048] 1) Phosphogypsum pretreatment: crush and sieve the phosphogypsum to a particle size of 1-5 mm, and adjust the adhering water content to the range of 5-10%;

[0049] 2) Adding powder components: After pretreatment, the passivation agent is added to the phosphogypsum in steps. The powder components are added in the first step and mixed evenly through the equipment;

[0050] 3) Adding liquid components: A spray device is installed at a suitable location in the discharging area such as the conveyor belt or the discharge port of the mixing equipment to add liquid components to the material spray, adjust the moisture content to 12-20%, and achieve dust reduction at the same time;

[0051] 4) Curing and waiting for inspection: After the two-step chemical passivation, the materials are piled up for inspection. The surface is covered with plastic film, HDPE film, non-woven fabric, plant straw and other materials to keep the moisture of the materials so that they can fully react. After meeting the standards, comprehensive utilization can be carried out as needed.

[0052] The present invention will be further described in detail below through examples. The protection scope of the present invention includes but is not limited to the following examples.

[0053] If specific experimental steps or conditions are not specified in the examples, the experiments can be carried out according to the conventional steps or conditions described in the literature in the art.

[0054] Unless otherwise specified, all reagents and raw materials used in the examples are commercially available products.

[0055] Example 1

[0056] In this embodiment, phosphogypsum from a slag depot in Yunnan is used as raw material, and the powder component and liquid component of the passivation agent are added step by step for harmless disposal. The powder component is a combination of calcium oxide, magnesium oxide and talcum powder, and the mass addition ratio (the ratio of each component to the mass of phosphogypsum) is 0.40%:0.10%:0.10%; the liquid passivation agent is a combination of aluminum sulfate and ferric chloride, and the mass addition ratio (the ratio of each component as solid to the mass of phosphogypsum) is 0.15%:0.10%.

[0057] The passivation agent is added in the order of powder first, then liquid. Before adding the powder, the phosphogypsum is pre-screened to a particle size of less than 3mm. The moisture content is adjusted to 8% by spreading and air-drying the material. The powder is then mixed with the raw materials using an industrial twin-shaft mixing device. The liquid agent is added via a counter-spraying spray at the equipment outlet, achieving a moisture content of 18%. After the phosphogypsum is rendered harmless and stored for inspection, it is covered with a simple plastic sheet to maintain moisture content.

[0058] Figure 2 shows SEM images of phosphogypsum before and after the addition of the powder and liquid reagents in Example 1 of the present invention. A2 shows the SEM image of the phosphogypsum before the reagents are added, and B2 shows the SEM image of the phosphogypsum after the reagents are added. Figure 2 shows that the addition of the detoxifying reagents destroys the plate-like crystal structure of the phosphogypsum, and the soluble calcium, iron, and aluminum in the reagents react with phosphorus and fluorine to form new particulate matter.

[0059] The harmlessness effect of phosphogypsum in this embodiment is shown in Table 1. The detection medium is the leachate prepared according to the standard of "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ 557-2010).

[0060] Table 1. Detoxification effect of phosphogypsum in Liushuqing slag depot (unit: mg / L)

[0061] As can be seen from Table 1, after adding the agent, the phosphogypsum leachate changed from acidic to alkaline, the phosphate concentration reduction rate reached 99.8%, and the fluoride reduction rate reached 92.4%. All indicators in the harmless phosphogypsum leachate were lower than the limit values ​​specified in the "Integrated Wastewater Discharge Standard" (GB 8978-1996).

[0062] Example 2

[0063] The phosphogypsum used in this example was obtained from a slag storage facility at a chemical company. Its initial moisture content was 9.2%. Prior to implementation, the phosphogypsum was passed through a 10-mesh sieve and then mixed evenly using an excavator. The phosphogypsum and reagent were then mixed using a concrete mixer with a 0.5-ton hopper capacity.

[0064] The passivation agent of this embodiment consists of a powder component and a liquid component, wherein the powder component is obtained by uniformly mixing calcium oxide and talc in a mass ratio of 4:1, and the liquid component is a polyaluminum chloride solution.

[0065] An excavator is used to load phosphogypsum into the upper hopper of a concrete mixer, and a powder component agent is weighed according to a mass addition ratio of 0.6% and added to the upper hopper. The phosphogypsum and the agent enter the drum through the upper hopper, and the mixing drum is driven by an electric motor and a reducer to rotate and mix. The mixture is pushed out of the mixing drum with the help of a hydraulic system. A spraying system is set at the discharge port to spray the liquid component agent. The mass addition ratio of the liquid component is 0.4% (calculated as solid polyaluminum chloride). The spraying is carried out manually during the unloading process. The moisture content of the phosphogypsum after spraying is 16.7%.

[0066] The materials evenly mixed by the concrete mixer were transferred to the inspection area for stacking and covered with HDPE film. After curing, three parallel samples were taken from the pile at 2d, 7d, and 14d. The leachate of the sample material was tested according to the "Solid Waste Leaching Toxicity Leaching Method - Horizontal Oscillation Method" (HJ557-2010). The test results of some samples are shown in Table 2.

[0067] Table 2 Pollutant content of leaching solution of phosphogypsum harmless material in Example 2

[0068] Table 2 shows that the phosphogypsum leachate changed from acidic to alkaline 2 days after the addition of the reagent. After 7 days of reaction, the phosphate concentration in the sample leachate decreased by 99.9%, and the fluoride concentration decreased by 93.6%. All indicators of the harmless phosphogypsum were lower than the limits specified in the "Integrated Wastewater Discharge Standard" (GB 8978-1996).

[0069] Example 3

[0070] In this example, aged phosphogypsum from a phosphate slag depot with a dry period of >6 months was selected. 10 tons of material was excavated from the surface layer to a depth of 1 m. The material was sieved with a 10-mesh stainless steel sieve to remove large agglomerated particles. Preliminary mixing and air-drying pretreatment were performed, and the moisture content was adjusted to 5.5%. The pH, fluoride, and initial phosphate leaching concentrations of the material were measured using the "Toxicity Leaching Method for Solid Waste" (HJ 557-2010).

[0071] According to the harmless agent ratio, a powder component composed of calcium oxide and talc (mass ratio of 2:1) and a liquid component composed of polyaluminum chloride and ferrous sulfate (mass ratio of 1:2) were prepared. Based on the initial leaching concentration of the target material indicators (pH, fluoride, and phosphate), 0.6% of the powder component (dose of drug / material amount) was added. Mixing and stirring were carried out using an ALLU screening bucket, and the powder component and material were fully mixed by turning the bucket back and forth three times. After the materials with the added powder components were stirred, they were stacked into a trapezoidal pile with a height of 0.5 m using a loader. During the unloading and stacking process, an electric sprayer was used to spray the liquid components. The liquid agent dosage was 0.3% (the dosage of polyaluminum chloride and ferrous sulfate and / or the amount of materials). After the stacking was completed, the moisture content was reduced to 13.6%. The materials were appropriately compacted using an excavator and covered with a rainproof cloth for maintenance. Samples were taken every day to determine the leachate of the sample materials for testing according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results of the 2d, 7d, and 14d samples are shown in Table 3.

[0072] Table 3 Target index leaching values ​​of materials before and after detoxification in Example 3

[0073] Table 3 shows that the phosphogypsum leachate changed from acidic to alkaline 2 days after adding the agent. After 7 days, the phosphate concentration decreased by 99.6%, and the fluoride concentration decreased by 80.4%. All indicators in the harmless phosphogypsum were lower than the limits specified in the "Integrated Wastewater Discharge Standard" (GB 8978-1996).

[0074] Example 4

[0075] This example primarily investigates the agglomeration and bleeding behavior of phosphogypsum with varying moisture contents during mixing. Low-moisture phosphogypsum (9.24%) refers to phosphogypsum with a surface layer of 0-0.5 m after 65 days of drying; medium-moisture phosphogypsum (19.87%) refers to phosphogypsum with a surface layer of 0-1 m after 20 days of drying; and high-moisture phosphogypsum (26.32%) refers to phosphogypsum with a surface layer of 0-1 m after 3 days of drying. Observations indicate that as the moisture content increases, mixing uniformity deteriorates, leading to agglomeration and bleeding during mixing. On-site photographs are shown in Figure 3.

[0076] In summary, the main innovative features of the technical solution of the present invention include but are not limited to:

[0077] (1) By compounding and using reagent components with different functions, the synergistic effect of different reagent components is brought into play, and efficient mixing of phosphogypsum and reagents is achieved, ensuring sufficient contact reaction between the reagents and pollutants, and achieving better passivation effect with a lower reagent addition ratio;

[0078] (2) According to the different properties and functions of the reagents, the reagents are divided into two components, solid phase and liquid phase, and added in steps, which can realize the adjustment of process parameters according to the properties of the reagents. The moisture content of phosphogypsum is reduced in the solid phase component mixing stage, which is conducive to uniform solid-solid mixing; after the solid-solid mixing is uniform, the passivation reagent is evenly added to the phosphogypsum in liquid form. The dust in the production process is controlled by spraying the liquid component, and the moisture content is increased at the same time, providing the high moisture content conditions required for the passivation reaction, achieving three goals at one stroke;

[0079] (3) Develop targeted engineering application methods of step-by-step dosing and step-by-step regulation to form a complete set of phosphogypsum modification processes including reagents, engineering application methods and equipment.

[0080] It should be noted that in the present invention, unless otherwise understood in conjunction with the full text, if there is an expression "A / B", it should be interpreted as any one of the following three parallel situations: A; B; A and B.

[0081] It should also be noted that, in the present invention, except for otherwise understanding in conjunction with the full text, if any, the relevant terms should be understood as follows. Relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements includes not only those elements, but also includes other elements not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the sentence "comprise a..." do not exclude the presence of other identical elements in the process, method, article or equipment comprising the elements.

[0082] Although the present invention has been disclosed above through the description of specific embodiments of the present invention, it should be understood that those skilled in the art may design various modifications, improvements or equivalents of the present invention within the spirit and scope of the attached solutions. Such modifications, improvements or equivalents should also be considered to be included in the scope of protection claimed by the present invention.

Claims

1. A phosphogypsum harmless agent, characterized in that: It consists of a powder component and a liquid component; wherein, The powder component is composed of an alkaline component and talcum powder, and the alkaline component is at least one of calcium oxide, magnesium oxide, calcium hydroxide, and magnesium hydroxide; The liquid component is an aqueous solution of at least one of a soluble iron salt, a soluble aluminum salt, and a soluble calcium salt; In the powder component, the mass ratio of the alkaline component to the phosphogypsum to be treated is 0.2% to 1.0%; the mass ratio of the talc powder to the phosphogypsum to be treated is 0.1% to 0.6%; The mass ratio of the liquid component to the phosphogypsum to be treated is 0.2-0.6% on a solid basis.

2. The phosphogypsum detoxifying agent according to claim 1, characterized in that: The soluble aluminum salt includes at least one of aluminum sulfate, aluminum chloride, and polyaluminum chloride; The soluble iron salt includes at least one of ferric sulfate, ferric chloride, ferrous sulfate, and polyferric sulfate; The soluble calcium salt is calcium chloride.

3. The phosphogypsum detoxifying agent according to claim 1, characterized in that: In the powder component, the mass ratio of the alkaline component to the talcum powder is 2-5:

1.

4. The phosphogypsum detoxifying agent according to claim 3, characterized in that: The powder component is composed of calcium oxide, magnesium oxide and talc, and the mass ratio of the powder component to the phosphogypsum to be treated is 0.40%, 0.10% and 0.10% respectively; the liquid component is composed of aluminum sulfate and ferric chloride, and the mass ratio of the powder component to the phosphogypsum to be treated is 0.15% and 0.10% respectively; or, The powder component is composed of calcium oxide and talcum powder, and the mass ratio of calcium oxide and talcum powder to the phosphogypsum to be treated is 0.48% and 0.12% respectively; the liquid component is polymerized aluminum oxide, and the mass ratio of calcium oxide and talcum powder to the phosphogypsum to be treated is 0.40%; or, The powder component is composed of calcium oxide and talcum powder, and the mass ratio of calcium oxide and talcum powder to the phosphogypsum to be treated is 0.40% and 0.20% respectively; The liquid component is composed of polyferric chloride and ferrous sulfate, and the liquid component is mixed with the phosphate rock to be treated. The mass ratios of the pastes were 0.10% and 0.20% respectively.

5. The phosphogypsum detoxifying agent according to any one of claims 1 to 4, characterized in that: The particle size of the alkaline component differs from the particle size distribution of the phosphogypsum particles to be treated by no more than ±5%, and the effective substance content is no less than 80%; The fineness of the talcum powder is not less than 400 meshes.

6. An engineering application method of a phosphogypsum harmless agent, characterized in that: The harmless agent for phosphogypsum is composed of a powder component and a liquid component; wherein: The powder component is composed of an alkaline component and talcum powder, and the alkaline component is at least one of calcium oxide, magnesium oxide, calcium hydroxide, and magnesium hydroxide; The liquid component is an aqueous solution of at least one of a soluble iron salt, a soluble aluminum salt, and a soluble calcium salt; The method comprises the following steps: S1, phosphogypsum pretreatment: crushing and sieving the phosphogypsum to a particle size of 1-5 mm, and adjusting the moisture content of the attached water to 5-10%; S2, adding powder components: uniformly mixing the phosphogypsum obtained in step S1 with the powder components in the phosphogypsum harmless agent; S3, adding liquid components: adding the liquid components in the phosphogypsum harmless agent to the material obtained in step S2, and adjusting the moisture content of the attached water to 12-20%; S4, curing and waiting for inspection: the materials obtained in step S3 are piled for curing, the moisture of the materials is maintained to allow them to fully react, and after the materials meet the inspection standards, they are comprehensively utilized as needed.

7. The engineering application method of the phosphogypsum harmless agent according to claim 6, characterized in that: The soluble aluminum salt includes at least one of aluminum sulfate, aluminum chloride, and polyaluminum chloride; The soluble iron salt includes at least one of ferric sulfate, ferric chloride, ferrous sulfate, and polyferric sulfate; The soluble calcium salt is calcium chloride.

8. The engineering application method of the phosphogypsum harmless agent according to claim 6, characterized in that: In the powder component, the mass ratio of the alkaline component to the phosphogypsum to be treated is 0.2% to 1.0%; the mass ratio of the talcum powder to the phosphogypsum to be treated is 0.1% to 0.6%; the mass ratio of the liquid component to the phosphogypsum to be treated is 0.2-0.6% in terms of solids.

9. The engineering application method of the phosphogypsum harmless agent according to claim 8, characterized in that: In the powder component, the mass ratio of the alkaline component to the talcum powder is 2-5:

1.

10. The engineering application method of the phosphogypsum harmless agent according to claim 9, characterized in that: The powder component is composed of calcium oxide, magnesium oxide and talc, and the mass ratio of the powder component to the phosphogypsum to be treated is 0.40%, 0.10% and 0.10% respectively; the liquid component is composed of aluminum sulfate and ferric chloride, and the mass ratio of the powder component to the phosphogypsum to be treated is 0.15% and 0.10% respectively; or, The powder component is composed of calcium oxide and talcum powder, and the mass ratio of calcium oxide and talcum powder to the phosphogypsum to be treated is 0.48% and 0.12% respectively; the liquid component is polymerized aluminum oxide, and the mass ratio of calcium oxide and talcum powder to the phosphogypsum to be treated is 0.40%; or, The powder component is composed of calcium oxide and talcum powder, and the mass ratio of calcium oxide and talcum powder to the phosphogypsum to be treated is 0.40% and 0.20% respectively; The liquid component consists of polyferric chloride and ferrous sulfate, and the mass ratios of the liquid component to the phosphogypsum to be treated are 0.10% and 0.20% respectively.

11. The engineering application method of the phosphogypsum harmless agent according to any one of claims 6 to 10, characterized in that: The particle size of the alkaline component differs from the particle size distribution of the phosphogypsum particles to be treated by no more than ±5%, and the effective substance content is no less than 80%; The fineness of the talcum powder is not less than 400 meshes.

12. The engineering application method of the phosphogypsum harmless agent according to any one of claims 6 to 10, characterized in that: In step S3, the liquid component is added in a spraying manner during the discharge or transfer process of the material obtained in step S2.

13. The engineering application method of the phosphogypsum harmless agent according to claim 12, characterized in that: In step S4, a material is covered on the surface to keep the moisture of the material, and the material is a plastic film, a HDPE film, a non-woven fabric or a plant straw.

14. The engineering application method of the phosphogypsum harmless agent according to any one of claims 6-10 and 13, characterized in that: In step S4, the stacking time is 2-14 days.

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