A method and system for high-salt wastewater solidification and evaporation treatment based on zero-valent aluminum and phosphogypsum powder co-milling materials

Abstract

The application provides a method and system for high-salt wastewater solidification and evaporation treatment based on zero-valent aluminum and phosphogypsum powder co-milling materials. The method co-mills zero-valent aluminum and phosphogypsum powder with high energy, realizes deep mechanical coating and interface activation by using the plastic deformation of aluminum and the brittle fracture of phosphogypsum, and prepares a cross-linked co-milling material. Then, the cross-linked co-milling material is added into high-salt wastewater for stirring and mixing solidification. In the solidification process, hydrogen evolution and heat release effects of chemical reaction between zero-valent aluminum and water in the composite material are utilized, the solidified material is rapidly converted into a three-dimensional polymer porous skeleton rich in channels in water, and the salt and pollutants in the wastewater are preliminarily locked. Finally, residual water is rapidly evaporated through natural or low-temperature drying, so that the high-salt wastewater is converted into a solid waste fully locking the salt and pollutants. The application realizes the treatment of difficult-to-treat high-salt wastewater by using large industrial solid waste, significantly reduces the amount of high-salt wastewater, reduces the treatment cost, and has obvious comprehensive benefits.

Description

Technical Field

[0001] This invention belongs to the technical field of reducing and harmlessly treating high-salt wastewater and utilizing industrial solid waste resources. Specifically, it relates to a method and system for solidifying and evaporating high-salt wastewater based on a ball-milled material of zero-valent aluminum and phosphogypsum powder. Background Technology

[0002] Chemical, pharmaceutical, and coking enterprises generate highly concentrated wastewater with high salinity (>10wt%), organic toxins, heavy metals, and high ammonia nitrogen during production processes and wastewater membrane treatment. This wastewater is extremely difficult to treat. On the one hand, this type of complex wastewater with high salinity cannot be treated biologically. Treating it by evaporation concentration (crystallization) involves high initial investment costs for equipment, as well as severe equipment corrosion and operational difficulties. On the other hand, incineration is also prohibitively expensive (the cost for hazardous waste disposal companies is generally around 1200 yuan / ton of water).

[0003] Low-temperature (room temperature) evaporation technology is a treatment technology that does not employ mechanical vapor recompression (MVR) evaporation equipment. This technology utilizes advanced principles such as significantly accelerated dehydration via micro-nano surface liquids and inorganic polymerization, employing a chemical solidification method to treat complex saline waste liquids. Specifically, an additional solidification component is added to the complex saline waste liquid, forming a solid, cross-linked, initially condensed state. This initially condensed solid is porous, creating numerous gas / water interfaces in the air, resulting in a large surface area for water evaporation. It can be rapidly dried using room-temperature dehumidification or low-temperature drying, ultimately forming a dried solid powder. However, existing solidification agents generally suffer from limitations such as narrow applicability, the need for additional alkaline activators, or reliance on external heat sources to achieve effective solidification and evaporation, leading to high treatment costs and difficulty in achieving deep chemical stabilization of multiple pollutants such as heavy metals, fluorine, and phosphorus.

[0004] Therefore, developing a widely applicable solidification agent that can fully absorb large quantities of industrial solid waste to achieve "waste treatment with waste" for low-cost, high-efficiency reduction and deep harmless treatment of various high-salt wastewater remains an urgent technical challenge. Summary of the Invention

[0005] One of the objectives of this invention is to provide a method for solidifying and evaporating high-salt wastewater based on a co-milled material of zero-valent aluminum and phosphogypsum powder. This method uses a cross-linked co-milled material obtained from zero-valent aluminum and phosphogypsum powder to treat high-salt wastewater. By utilizing the characteristics of rapid evaporation and dehydration of the solidified body under low-temperature conditions, the method achieves the reduction and stabilization of high-salt wastewater, as well as the resource utilization and disposal of industrial solid waste phosphogypsum.

[0006] The second objective of this invention is to provide a system for solidifying and evaporating high-salt wastewater based on a ball-milled material of zero-valent aluminum and phosphogypsum powder to implement the above-mentioned method.

[0007] One of the technical solutions adopted by this invention to achieve its objective is to provide a method for solidification and evaporation treatment of high-salt wastewater based on a ball-milled material of zero-valent aluminum and phosphogypsum powder, comprising the following steps: S1. Zero-valent aluminum is mixed with phosphogypsum powder and ball-milled under an inert atmosphere to obtain a cross-linked co-ball-milled material; S2. Add the cross-linked co-milling material to the high-salt wastewater to be treated and mix evenly to obtain the solidified precursor; S3. Allow the curing precursor to stand for a certain period of time to carry out the curing reaction and obtain the cured product; S4. The cured product is dried to obtain a stable porous solid that retains salt and heavy metals.

[0008] The overall concept and inventive principle of this invention are as follows: The method for solidification and evaporation treatment of high-salt wastewater provided by this invention first prepares a cross-linked co-milling material using zero-valent aluminum and industrial solid waste phosphogypsum as raw materials. Zero-valent aluminum possesses excellent ductility, and under the intense mechanical extrusion and friction of ball milling, it can achieve a thorough physical bond with phosphogypsum powder. Simultaneously, under this mechanical force, the oxide film on the surface of zero-valent aluminum is continuously destroyed, and the fluorine, phosphorus, and other components in the phosphogypsum undergo a solid-phase interfacial reaction with the exposed fresh aluminum matrix, forming a highly reactive fluorine-aluminum-phosphorus cross-linked precursor material (i.e., the cross-linked co-milling material). Subsequently, this cross-linked co-milled material was added to high-salt wastewater. The zero-valent aluminum component reacted with water, and the active aluminum ions generated within the system underwent a condensation reaction with phosphate and fluoride ions in the waste liquid and phosphogypsum, generating structures such as hydrated aluminum phosphate and aluminum fluoride, which then underwent hydroxyl cross-linking, initially constructing a three-dimensional polymer framework. Simultaneously, the reaction of zero-valent aluminum with water released a large number of gas microbubbles, causing the slurry to expand during the curing process, forming a loose, porous structure rich in channels in situ. Accompanying the vigorous self-foaming process, the reaction of zero-valent aluminum with water released a certain amount of heat energy, which facilitated further curing. During the static setting period of the cured precursor, the slurry, supported by microbubbles, completed volume expansion and gradually stabilized, and the cross-linking polymerization reaction was fully completed. The system macroscopically transformed from a liquid or colloidal state to a loose, porous solid state rich in channels within a short time. At the same time, the salt in the waste liquid and the heavy metals, fluorine, and phosphorus pollutants from the phosphogypsum were firmly encapsulated within this three-dimensional porous framework. Finally, the solidified product is dried to vaporize and evaporate the residual moisture, ultimately yielding a stable porous solid that retains salt and heavy metals. This method achieves low-cost, high-efficiency volume reduction and deep harmless treatment of high-salt wastewater, while also fully utilizing large quantities of industrial solid waste phosphogypsum, thus realizing the goal of "treating waste with waste."

[0009] Further, in step S1, the mass ratio of zero-valent aluminum to phosphogypsum powder is 1:4-19. The cross-linked co-ball milling material prepared by this invention uses phosphogypsum, a bulk industrial solid waste, as the main solidification material, highlighting the concept of "treating waste with waste" and significantly reducing the treatment cost of high-salt wastewater. At the same time, the amount of zero-valent aluminum added to the cross-linked co-ball milling material is controlled at 5wt%-20wt% to ensure the full reaction of zero-valent aluminum and the safe and stable operation of the solidification system.

[0010] Further, in step S1, the zero-valent aluminum uses aluminum powder and / or aluminum shavings with an aluminum content greater than 90wt%, and the particle size of the zero-valent aluminum is 200-900μm; the particle size of the phosphogypsum powder is 300-1000μm. This invention uses micron-sized pure aluminum powder or aluminum shavings as the raw material for zero-valent aluminum, which, compared to nano-aluminum and coarse-particle aluminum, has the characteristics of safety, controllability, and high reaction efficiency. Micron-sized aluminum not only avoids the high risks and high costs associated with the easy agglomeration, spontaneous combustion, and explosion of nano-aluminum, but also ensures a mild and controllable reaction, preventing slurry splashing caused by excessive reaction, and allowing hydrogen evolution foaming and heat release to stably match the static curing cycle of the slurry. In addition, the appropriate reactivity and specific surface area of ​​micron-sized aluminum allow for more efficient and uniform reaction and combination with phosphogypsum, resulting in sufficient gas production and heat release in wastewater, which can be completely consumed, avoiding metal residue and material waste caused by the formation of a "core-shell" dead zone inside coarse particles.

[0011] Furthermore, in step S1, the inert atmosphere for ball milling includes inert gases such as argon or nitrogen. The inert gas environment can prevent the exposed fresh aluminum from being re-oxidized during the ball milling process.

[0012] Furthermore, in step S1, the ball milling process uses a planetary ball mill with zirconia balls, agate balls, or alumina balls as grinding media. These media can provide sufficient mechanical impact and shear force to induce brittle fracture of phosphogypsum, while avoiding the interference of ferromagnetic impurities that may be introduced by traditional stainless steel ball mills in subsequent reactions.

[0013] Further, in step S1, the ball-to-material mass ratio in the ball milling process is 10:1-20:1, the milling speed is 200-400 r / min, and the milling time is 2-6 hours. When the ball-to-material mass ratio is below 10:1, the mechanical impact energy input within the milling jar is insufficient, failing to allow zero-valent aluminum to undergo sufficient plastic deformation and uniformly coat the phosphogypsum surface. Conversely, when the ball-to-material ratio is above 20:1, it not only easily leads to over-grinding of the material and severe wear of the grinding media, but also excessive destruction of the microstructure, significantly increasing unnecessary energy consumption. If the milling speed is too low or the time is too short, the mechanochemical activation of the phosphogypsum crystals is incomplete, failing to expose sufficient active impurities (fluorine, phosphorus). Conversely, if the milling speed is too high or the grinding time is too long, intense and continuous mechanical friction will generate localized high temperatures, causing severe agglomeration and clumping of the originally dispersed aluminum-phosphogypsum composite powder, which will reduce the specific surface area of ​​the material and cause it to lose its optimal rapid foaming and reactivity in the waste liquid.

[0014] In step S1 of the present invention, after the ball milling process described above, zero-valent aluminum undergoes plastic deformation under the high-energy impact of the grinding media, extending into thin sheets or films and tightly coating the fresh fracture surface of the phosphogypsum particles that have undergone brittle fracture, forming aluminum-phosphogypsum mechanically coated microparticles.

[0015] Further, in step S2, the total dissolved solids content in the high-salt wastewater to be treated is 10wt%-50wt%; the inorganic salt ions in the total dissolved solids include one or more metal cations selected from sodium ions, potassium ions, calcium ions, and magnesium ions, as well as one or more anions selected from chloride ions, sulfate ions, and nitrate ions.

[0016] Furthermore, the high-salinity wastewater also contains one or more of the following: organic pollutants, heavy metal ions, or ammonia nitrogen.

[0017] Furthermore, in step S2, the dosage of the cross-linked co-milled material in the high-salt wastewater to be treated is 100-400 kg / ton. This suitable dosage balances the effective cross-linking degree of the system with the material disposal cost, avoiding both defects in the cross-linking network construction caused by insufficient dosage and ineffective increase in solid waste due to reagent redundancy.

[0018] Furthermore, in step S2, mechanical stirring is used for mixing at a speed of 150-300 r / min for 5-15 min to prevent local agglomeration of the cross-linked co-milled material in the waste liquid. In this invention, appropriate stirring speed and time are necessary conditions for constructing a stable "gas-liquid-solid" three-phase homogeneous reaction system and ensuring the smooth formation of the subsequent porous framework.

[0019] Furthermore, in step S3, the settling time is 10-30 minutes. During the stirring and settling solidification process in steps S2 and S3 of this invention, the zero-valent aluminum component in the cross-linked ball milling material reacts with water in the waste liquid and releases a large number of gas microbubbles and heat, causing the internal temperature of the solidified body to rise by 5-15°C compared to the ambient temperature. This self-heating reaction helps reduce the energy consumption of solidification and evaporation treatment of high-salt wastewater and accelerates the evaporation and discharge of water.

[0020] Further, in step S4, the drying temperature is 15-80℃, and the drying methods include natural drying and / or low-temperature drying. Natural drying involves spreading the high-salt wastewater solidified body flat in an open container and evaporating it under natural ventilation at an ambient temperature of 15-35℃. Low-temperature drying involves evaporating it using a forced-air drying device at 35-80℃. The drying time depends on the specific circumstances, continuing until the moisture content of the dried solidified body is below 25%. During the drying process, spreading the solidified body as thinly as possible in the open container maximizes the gas-solid contact area macroscopically. Simultaneously, combined with ventilation or forced-air drying, it rapidly removes saturated water vapor from the surface of the solidified body, greatly improving the overall evaporation and removal rate of moisture. This invention controls the upper limit of the drying temperature to 80℃, ensuring a relatively fast evaporation rate while preventing the risk of secondary pollutant release due to pyrolysis of the solidified body.

[0021] Furthermore, in step S4, the post-treatment methods for the stable porous solid include landfill disposal or application as a filling material in civil engineering. The dried solidified body finally obtained by this invention can be directly and safely landfilled or used as an engineering filling material for comprehensive resource utilization. Because the free salt in high-salt wastewater and the harmful substances such as fluorine, phosphorus, and heavy metals associated with phosphogypsum are deeply chemically bonded and physically trapped inside a highly stable three-dimensional polymer porous framework, its leaching toxicity is far below the hazardous waste identification standard. Therefore, it can be directly and safely landfilled as general solid waste, eliminating the risk of secondary pollution. At the same time, thanks to the lightweight, loose, porous, and stable framework mechanical properties of the solidified body after foaming and expansion, it can also replace traditional earthwork and be used as a roadbed filler, backfill material for mining goaf areas, or auxiliary building material aggregate, etc. This not only broadens the channels for material disposal, but also, on the basis of reducing the volume of high-concentration waste liquid, further opens up the final closed loop from "treating waste with waste" to "harmless and resource-based utilization" of multi-source industrial solid waste.

[0022] The second technical solution adopted by the present invention is to provide a system for solidification and evaporation treatment of high-salt wastewater based on ball milling material of zero-valent aluminum and phosphogypsum powder for achieving the method described in the first objective of the present invention, comprising: a dosing tank, a high-salt wastewater transport pipeline, a mixing tank, a wet solidified body transport pipeline, a low-temperature heat source, a drying tank, a solidified material silo, a waste salt disposal device, a condensate wastewater pipeline, and a condensate wastewater collection device; The mixing tank is used to mix the cross-linked ball milling material provided by the dosing tank with the high-salt wastewater to be treated transported by the high-salt wastewater transport pipeline to obtain a solidification precursor; the wet solidified body transport pipeline is used to transport the solidification precursor to the drying tank for solidification reaction and drying treatment; the drying tank is equipped with a low-temperature heat source and a condensate wastewater pipeline, the condensate wastewater pipeline being connected to a condensate wastewater collection device; the material outlet of the drying tank is connected to the solidification silo, and the outlet of the solidification silo is connected to a waste salt disposal device; the waste salt disposal device is used for post-processing of the stable porous solid.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention provides a method for solidifying and evaporating high-salt wastewater based on a co-milled material of zero-valent aluminum and phosphogypsum powder. Using phosphogypsum and zero-valent aluminum as the main raw materials, a highly active cross-linked co-milled material is prepared through the mechanochemical action of ball milling. Upon contact with water, this cross-linked co-milled material spontaneously undergoes condensation, gas generation, foaming, and gentle self-heating, causing the slurry to expand and solidify in situ into a lightweight, porous, three-dimensional framework in a short time, increasing the evaporation area and reducing dehydration energy consumption. The solidified body can be rapidly dried under low-temperature conditions. Salt and heavy metals associated with phosphogypsum in the wastewater are deeply chemically bonded and physically encapsulated within the stable framework, resulting in low leaching toxicity. This method has a simple process, requires no high-temperature or high-energy-consumption equipment, and achieves a resource-based closed loop of efficient reduction and harmless treatment of high-salt wastewater and synergistic disposal of industrial solid waste.

[0024] (2) This invention provides a system for the solidification and evaporation treatment of high-salt wastewater based on a co-milled material of zero-valent aluminum and phosphogypsum powder. The system mixes the cross-linked co-milled material and wastewater in a mixing tank to form a homogeneous solidification precursor. A drying tank, combined with a low-temperature heat source, utilizes the self-heating reaction to achieve static expansion solidification and efficient evaporation dehydration, while recovering the condensate for recycling. The treatment terminal connects to a solidification silo and a waste salt disposal device. The resulting stable porous solid can be directly and safely landfilled or used as building materials. The entire system, from dosing, solidification, drying to final disposal, is continuous, safe, and controllable, providing a reliable solution for the low-cost, industrialized treatment of high-salt wastewater. Attached Figure Description

[0025] Figure 1 This is a schematic flowchart of a method for solidifying and evaporating high-salt wastewater based on a ball-milled material of zero-valent aluminum and phosphogypsum powder, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a system for solidifying and evaporating high-salt wastewater based on a ball-milled material of zero-valent aluminum and phosphogypsum powder, provided in an embodiment of the present invention. Figure 3 This is a comparison diagram of wastewater before and after solidification and drying in Example 2 of the present invention; wherein, (a) is the high-salt wastewater to be treated; (b) is the solidification reaction in progress; and (c) is the porous solid product. Figure 4 This is a comparison diagram of wastewater before and after solidification and drying in Example 3 of the present invention; wherein, (a) is the high-salt wastewater to be treated; (b) is the solidification reaction in progress; and (c) is the porous solid product. Among them, 1-dosing tank; 2-high salinity wastewater transport pipeline; 3-mixing tank; 4-wet solidified body transport pipeline; 5-low temperature heat source; 6-drying tank; 7-solidified material silo; 8-waste salt treatment device; 9-condensate wastewater pipeline; 10-condensate wastewater collection device. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention provides a method for solidification and evaporation treatment of high-salt wastewater based on a co-milling material of zero-valent aluminum and phosphogypsum powder, the process flow diagram of which is shown below. Figure 1 As shown, it includes the following steps: Step 1: Mix zero-valent aluminum with phosphogypsum powder and ball mill under an inert atmosphere to obtain a cross-linked co-ball milled material; wherein the mass ratio of zero-valent aluminum to phosphogypsum powder is 1:4-19; the zero-valent aluminum is aluminum powder and / or aluminum shavings with an aluminum content greater than 90wt%, and the particle size of the zero-valent aluminum is 200-900μm; the particle size of the phosphogypsum powder is 300-1000μm. The ball milling speed is 200-400 r / min, and the ball milling time is 2-6 hours; the ball milling uses zirconia balls, agate balls, or alumina balls as grinding media, and the ball-to-material mass ratio is 10:1-20:1.

[0028] Step 2: Add the cross-linked co-milling material to the high-salt wastewater to be treated and mix evenly to obtain the solidified precursor. The total dissolved solids content in the high-salt wastewater to be treated is 10wt%-50wt%. The inorganic salt ions in the total dissolved solids include one or more metal cations selected from sodium, potassium, calcium, and magnesium ions, and one or more anions selected from chloride, sulfate, and nitrate ions. The high-salt wastewater also contains one or more organic pollutants, heavy metal ions, or ammonia nitrogen. The dosage of the cross-linked co-milling material in the high-salt wastewater to be treated is 100-400 kg / ton. Mixing is carried out by mechanical stirring at a speed of 150-300 r / min for 5-15 min.

[0029] Step 3: Let the curing precursor stand for 10-30 minutes to carry out the curing reaction and obtain the cured product; Step 4: The solidified product is dried to obtain a stable porous solid that retains salts and heavy metals. The drying temperature is 15-80℃, and the drying method includes natural drying and / or low-temperature drying. The stable porous solid can be disposed of through landfill or used as a filler material in civil engineering projects.

[0030] Figure 2 A system for implementing the above method is provided in an embodiment of the present invention, comprising: a dosing tank 1, a high-salt wastewater transport pipeline 2, a mixing tank 3, a wet solidified body transport pipeline 4, a low-temperature heat source 5, a drying tank 6, a solidified material silo 7, a waste salt disposal device 8, a condensate wastewater pipeline 9, and a condensate wastewater collection device 10.

[0031] The mixing tank 3 is used to mix the cross-linked ball milling material from the dosing tank 1 with the high-salt wastewater to be treated transported by the high-salt wastewater transport pipeline 2 to obtain a solidification precursor; the wet solidified body transport pipeline 4 is used to transport the solidification precursor to the drying tank 6 for solidification reaction and drying treatment; the drying tank 6 is equipped with a low-temperature heat source 5 and a condensate wastewater pipeline 9, which is connected to a condensate wastewater collection device 10; the material outlet of the drying tank 6 is connected to a solidification silo 7, and the outlet of the solidification silo is connected to a waste salt disposal device 8; the waste salt disposal device 8 is used for post-processing of the stable porous solid.

[0032] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0033] Example 1 This embodiment provides a method for solidification and evaporation treatment of high-salt wastewater based on a ball-milled material of zero-valent aluminum and phosphogypsum powder. The wastewater source is: concentrated mother liquor from reverse osmosis (RO) of a chemical plant; salt content is 15 wt% (mainly NaCl and Na2SO4), containing organophosphorus compounds (tetramethylphosphorus chloride THPC, total phosphorus concentration 500 mg / L), and heavy metal Cu. 2+ The concentration was 50 mg / L, and the pH was 5.5. The method included the following steps: Step 1: Co-ball milling preparation: Weigh 15 parts of zero-valent micron aluminum powder with a median particle size of 200 μm and 85 parts of industrial phosphogypsum powder (pre-dried) with an average particle size of 300 μm. Add both to a planetary ball mill, using zirconia balls as the grinding medium, with a ball-to-material mass ratio of 15:1. Argon gas is introduced into the mill jar for protection, and the milling speed is set to 300 r / min for 4 hours to obtain a well-crosslinked co-ball milled material with good mechanical coating.

[0034] Step 2, Mixing and Crosslinking Network Construction: Place 1 kg of the above-mentioned reverse osmosis concentrated mother liquor into the reaction tank, and add the crosslinked co-milling material prepared in Step 1 at a dosage of 100 kg / ton. Turn on the mechanical stirrer at 200 r / min and stir for 10 minutes. During the stirring process, a large number of tiny bubbles begin to be generated inside the slurry.

[0035] Step 3, Static Curing: Stop stirring and let the slurry stand; with the reaction of aluminum and water, the system temperature rises by 10°C compared to the ambient temperature. The slurry expands significantly under the support of microbubbles and rapidly crosslinks and gels within 20 minutes, completely transforming into a loose and porous solid.

[0036] Step 4, Drying and Evaporation: Spread the foamed and solidified porous body on a tray (about 5 cm thick) and place it in a 40℃ forced-air drying oven for 12 hours to dry it. Finally, 300g of dried solidified body with a moisture content of 14.6% is obtained, and the waste liquid weight is reduced by 70%.

[0037] Example 2 This embodiment provides a method for solidification and evaporation treatment of high-salt wastewater based on a ball-milled material of zero-valent aluminum and phosphogypsum powder. The wastewater source is concentrated biochemical tailwater from a coking plant; salt content 10 wt%, COD 2000 mg / L, ammonia nitrogen 300 mg / L. The method includes the following steps: Step 1: Co-ball milling preparation: Weigh 5 parts of zero-valent micron aluminum powder with a median particle size of 500 μm and 95 parts of industrial phosphogypsum powder (pre-dried) with an average particle size of 500 μm. Add both to a planetary ball mill, using agate balls as the grinding medium, with a ball-to-material mass ratio of 10:1. Purge the ball mill jar with nitrogen for protection, set the rotation speed to 200 r / min, and the grinding time to 6 hours to obtain a well-crosslinked co-ball milled material with mechanical coating.

[0038] Step 2, Mixing and Crosslinking Network Construction: Take 1 kg of the above-mentioned concentrated biochemical wastewater and place it in the reaction tank. Add the crosslinked co-milling material prepared in Step 1 at a dosage of 400 kg / ton. Turn on the mechanical stirrer at 150 r / min and stir for 15 minutes. During the stirring process, a large number of tiny bubbles begin to be generated inside the slurry.

[0039] Step 3, Static Curing: Stop stirring and let the slurry stand; with the reaction of aluminum and water, the system temperature rises by 15°C compared to the ambient temperature. The slurry expands significantly under the support of microbubbles and rapidly crosslinks and gels within 30 minutes, completely transforming into a loose and porous solid.

[0040] Step 4, Drying and Evaporation: Spread the foamed and cured porous body flat on a tray (about 5 cm thick) and place it outdoors in a well-ventilated area (ambient temperature about 25°C) to dry naturally for 12 hours. Finally, 470g of dried solidified body with a moisture content of 6.5% is obtained, and the waste liquid weight is reduced by 53%.

[0041] Example 3 This embodiment provides a method for solidification and evaporation treatment of high-salt wastewater based on a ball-milled material of zero-valent aluminum and phosphogypsum powder. The wastewater source is residual liquid from MVR evaporation at a pharmaceutical company; it has a salt content as high as 45 wt%, and its composition is extremely complex and viscous. The method includes the following steps: Step 1: Co-ball milling preparation: Weigh 20 parts of zero-valent micron aluminum shavings with a median particle size of 900 μm and 80 parts of industrial phosphogypsum powder (pre-dried) with an average particle size of 1000 μm. Add both to a planetary ball mill, using agate balls as the grinding media, with a ball-to-material mass ratio of 20:1. Purge the mill jar with nitrogen for protection, set the rotation speed to 400 r / min, and the grinding time to 2 hours to obtain a well-coated, cross-linked co-ball milled material.

[0042] Step 2, Mixing and Crosslinking Network Construction: Take 1 kg of the above MVR evaporation residue and place it in the reaction tank. Add the crosslinked co-milled material prepared in Step 1 at a dosage of 200 kg / ton. Turn on the mechanical stirrer at 300 r / min and stir for 5 minutes. During the stirring process, a large number of tiny bubbles begin to be generated inside the slurry.

[0043] Step 3, Static Curing: Stop stirring and let the slurry stand; with the reaction of aluminum and water, the system temperature rises by 5°C compared to the ambient temperature. The slurry expands significantly under the support of microbubbles and rapidly crosslinks and gels within 15 minutes, completely transforming into a loose and porous solid.

[0044] Step 4, Drying and Evaporation: Spread the foamed and cured porous body flat on a tray (about 5 cm thick) and place it in an 80℃ forced-air drying oven for 12 hours to dry. Finally, 530g of dried solidified body with a moisture content of 11.2% was obtained, and the waste liquid weight was reduced by 47%.

[0045] Comparative Example 1 Operating procedures: The same raw materials and proportions as in Example 1 (15 parts micron-sized aluminum powder, 85 parts industrial phosphogypsum) were used. However, instead of planetary ball milling, the powder was dry-mixed at room temperature for 4 hours in a mixer. Then, 100g of the mixed powder was added to 1000g of the same waste liquid as in Example 1 and stirred at 200 r / min for 10 minutes. Other steps and treatment conditions were the same.

[0046] Experimental phenomena: After adding waste liquid, the slurry reaction was slow, the foaming process was extremely uneven, the solidified body after standing and molding was brittle and had extremely poor strength. After drying at 40℃ for 12 hours, 850g of dried solidified body with a water content of 43.9% was obtained, and the wastewater weight was reduced by 15%.

[0047] Comparative Example 2 Operating Procedures: The process flow is exactly the same as in Example 1, but the 15 parts of micronized aluminum powder in the formula are replaced with 15 parts of industrial fly ash (containing 28.5% alumina, 52.3% silica, 6.4% iron oxide, and 4.2% calcium oxide by weight percentage). This fly ash is then ball-milled with 85 parts of industrial phosphogypsum in a planetary ball mill for 4 hours. Subsequently, 100g of this co-milled powder is added to 1000g of the same waste liquid from Example 1, stirred at 200 r / min for 10 minutes, and then allowed to stand. Other steps and treatment conditions are the same.

[0048] Experimental phenomena: After adding waste liquid, the slurry did not foam or expand from beginning to end. The solidified body after standing and molding was dense and heavy, and was in the form of a solid block. After drying at 40℃ for 12 hours, 750g of dried solidified body with a water content of 35.7% was obtained, and the wastewater reduced the weight by 25%.

[0049] As can be seen from the above embodiments and comparative examples, the method for solidifying and evaporating high-salt wastewater provided by the present invention constructs a highly reactive precursor material through co-ball milling of zero-valent aluminum and phosphogypsum powder, triggering a synergistic effect of polycondensation crosslinking, gas generation foaming and self-heating in the wastewater, thereby achieving rapid solidification and efficient dehydration.

[0050] Comparing Example 1 and Comparative Example 1, with the same proportions, only replacing co-ball milling with simple dry mixing resulted in uneven foaming and poor strength in the cured body. The moisture content after drying was as high as 43.9%, and the weight loss of the waste liquid was only 15%. This indicates that simple physical mixing cannot destroy the oxide film on the aluminum surface and expose the active components of phosphogypsum. The high-energy mechanical force of planetary ball milling is a necessary condition for inducing solid-phase interfacial reactions and constructing aluminum-phosphorus-fluorine crosslinked precursors. Comparative Example 2, which replaced zero-valent aluminum with an equal amount of fly ash, could undergo a gelation reaction with phosphogypsum, but the cured body was dense and non-foaming, with a weight loss of only 25%, significantly lower than the 70% in Example 1. This shows that the triple functions of zero-valent aluminum—foaming and pore formation, chemical crosslinking, and in-situ heating—are irreplaceable and are the core of achieving low-temperature and efficient dehydration.

[0051] Examples 1-3, targeting RO concentrate, biochemical effluent, and MVR residue with salt contents of 10%-45%, respectively, achieved rapid solidification and weight reduction rates of 47%-70% by adjusting the aluminum ratio, particle size, and process parameters. This demonstrates the good adaptability of the method of the present invention to different types of high-salt wastewater. The solidified bodies obtained in each example all had a water content of less than 15%, with salts and heavy metals stably encapsulated within a three-dimensional framework. In contrast, the comparative products exhibited a loose structure, high water content, and poor fixation effect, further confirming the outstanding advantages of the present invention in terms of volume reduction and harmlessness.

[0052] In summary, this invention provides a method and system for solidifying and evaporating high-salt wastewater based on a ball-milled material of zero-valent aluminum and phosphogypsum powder. Using mechanochemical activation as the core method, zero-valent aluminum as the active component, and phosphogypsum (a bulk industrial solid waste) as the main raw material, it achieves rapid solidification and efficient dehydration of high-salt wastewater under low-temperature conditions. This method avoids the problems of high energy consumption and high cost of membrane concentration associated with traditional thermal treatment, and differs from conventional gelation solidification techniques that rely solely on hydration reactions. Through a "waste-to-waste" approach, it simultaneously reduces and renders high-salt wastewater harmless while also synergistically utilizing industrial solid waste phosphogypsum, thus achieving the goal of solid waste resource utilization and demonstrating promising industrial application prospects.

[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A method for solidification and evaporation treatment of high-salt wastewater based on a ball-milled material of zero-valent aluminum and phosphogypsum powder, characterized in that, Includes the following steps: S1. Zero-valent aluminum is mixed with phosphogypsum powder and ball-milled under an inert atmosphere to obtain a cross-linked co-ball-milled material; S2. Add the cross-linked co-milling material to the high-salt wastewater to be treated and mix evenly to obtain the solidified precursor; S3. Allow the curing precursor to stand for a certain period of time to carry out the curing reaction and obtain the cured product; S4. The cured product is dried to obtain a stable porous solid that retains salt and heavy metals.

2. The method according to claim 1, characterized in that, In step S1, the mass ratio of zero-valent aluminum to phosphogypsum powder is 1:4-19; the zero-valent aluminum is aluminum powder and / or aluminum shavings with an aluminum content greater than 90wt%, and the particle size of the zero-valent aluminum is 200-900μm; the particle size of the phosphogypsum powder is 300-1000μm.

3. The method according to claim 1, characterized in that, In step S1, the ball milling speed is 200-400 r / min, and the ball milling time is 2-6 hours; the ball milling uses zirconia balls, agate balls or alumina balls as grinding media, and the ball-to-material mass ratio is 10:1-20:

1.

4. The method according to claim 1, characterized in that, In step S2, the total dissolved solids content in the high-salt wastewater to be treated is 10wt%-50wt%; the inorganic salt ions in the total dissolved solids include one or more metal cations selected from sodium ions, potassium ions, calcium ions, and magnesium ions, as well as one or more anions selected from chloride ions, sulfate ions, and nitrate ions.

5. The method according to claim 1, characterized in that, In step S2, the dosage of the cross-linked co-ball milling material in the high-salt wastewater to be treated is 100-400 kg / ton.

6. The method according to claim 1, characterized in that, In step S2, mechanical stirring is used for mixing, with a stirring speed of 150-300 r / min and a stirring time of 5-15 min.

7. The method according to claim 1, characterized in that, In step S3, the settling time is 10-30 minutes.

8. The method according to claim 1, characterized in that, In step S4, the drying temperature is 15-80℃, and the drying methods include drying under natural conditions and / or low-temperature drying.

9. The method according to claim 1, characterized in that, In step S4, the post-processing methods of the stable porous solid include landfill disposal or application as a filling material in civil engineering.

10. A system for solidifying and evaporating high-salt wastewater based on a co-milled material of zero-valent aluminum and phosphogypsum powder, used to implement the method according to any one of claims 1-9, characterized in that, include: Dosing tank (1), high-salt wastewater transport pipeline (2), mixing tank (3), wet solidified body transport pipeline (4), low-temperature heat source (5), drying tank (6), solidified material silo (7), waste salt disposal device (8), condensate wastewater pipeline (9) and condensate wastewater collection device (10); The mixing tank (3) is used to mix the cross-linked ball milling material in the dosing tank (1) with the high-salt wastewater to be treated transported by the high-salt wastewater transport pipeline (2) to obtain a solidified precursor; the wet solidified body transport pipeline (4) is used to transport the solidified precursor to the drying tank (6) for solidification reaction and drying treatment; the drying tank (6) is equipped with a low-temperature heat source (5) and a condensate wastewater pipeline (9), and the condensate wastewater pipeline (9) is connected to a condensate wastewater collection device (10); the material outlet of the drying tank (6) is connected to the solidified silo (7), and the outlet of the solidified silo is connected to the waste salt disposal device (8); the waste salt disposal device (8) is used to post-process the stable porous solid.

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