A silicon powder conditioning agent, its preparation method and application

Abstract

This invention relates to the field of water treatment technology and discloses a silica fume conditioner and its preparation method, comprising: 20-40% inorganic coagulant, 5-15% organic polymer coagulant, 3-10% natural polymer coagulant aid, 10-25% demulsifier, 2-8% synthetic coagulant aid, and the balance being water. This invention combines the demulsifier with various coagulants and coagulants. The demulsifier preferentially disrupts the oil-water interface film, releasing the encapsulated silica fume and eliminating the "colloidal protection" effect of oil on the silica fume surface. The inorganic and organic coagulants rapidly neutralize and adsorb the exposed silica fume particles, forming flocs with good settling properties and easy filtration. Meanwhile, inorganic coagulants provide positive charges, efficiently neutralizing negatively charged fine silica powder; high molecular weight CPAM and strong cationic PDADMAC form long-chain bridging and patching effects, specifically capturing 1-5μm fine particles, while improving the formation of easily filterable flocs from larger silica particles; natural polymers further increase the volume and density of flocs, preventing flocs from breaking under shear.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more specifically, to a silica powder conditioner and its preparation method. Background Technology

[0002] In the multi-wire cutting process of photovoltaic and semiconductor silicon rods, the circulating cutting fluid plays a crucial role in cooling, lubrication, and removing silicon (Si) debris. This circulating water system requires a silicon powder content of less than 50 ppm in the water. However, in actual operation, the circulating water undergoes emulsification due to long-term use and the potential mixing of lubricating oil from the equipment. This emulsified oil coating encapsulates the silicon powder particles, altering their surface properties, making them oleophilic and hydrophobic, and imbuing them with a stable electrical charge. This drastically increases the difficulty of separating the silicon powder from the water.

[0003] Existing technologies typically employ primary sedimentation combined with bag filtration or plate and frame filtration for solid-liquid separation. However, for fine silica powder (especially particles around 5μm) in emulsion systems, traditional filtration and pressure filtration methods have significant drawbacks:

[0004] Filtration penetration: Fine silica powder can easily penetrate filter bags or filter cartridges with a precision of 1-5μm, causing the filtered water to turn black, which affects cutting efficiency and silicon wafer yield when reused.

[0005] Low filter press efficiency: Emulsified oil makes the silica powder slurry viscous, clogging the filter cloth. The resulting filter cake has a high moisture content, is difficult to peel off, has a long filter press cycle, and has low operating efficiency.

[0006] Water quality deterioration: Silicon powder and oil that are not effectively removed accumulate in the system, eventually leading to deterioration of the circulating water quality, which not only affects the cutting process but also shortens the equipment life.

[0007] Therefore, proposing a silicon powder conditioning agent has significant practical implications. Summary of the Invention

[0008] In view of this, the present invention proposes a silicon powder conditioning agent, its preparation method and application, aiming to solve at least one of the problems in the background art.

[0009] This invention provides a silicon powder conditioning agent comprising the following components by mass fraction:

[0010] Inorganic coagulant 20-40%, organic polymer coagulant 5-15%, natural polymer coagulant 3-10%, demulsifier 10-25%, synthetic coagulant 2-8%, balance water.

[0011] Preferably, the inorganic coagulant is a mixture of polyaluminum chloride (PAC) and polyferric sulfate (PFS), wherein the mass ratio of polyaluminum chloride (PAC) to polyferric sulfate (PFS) is (1~3):1, the basicity of polyaluminum chloride (PAC) is 80%, and the total iron content of polyferric sulfate (PFS) is 19%.

[0012] Preferably, the organic polymer coagulant is a mixture of cationic polyacrylamide (CPAM) and polydimethyldiallyl ammonium chloride (PDADMAC), wherein the mass ratio of cationic polyacrylamide (CPAM) to polydimethyldiallyl ammonium chloride (PDADMAC) is (1~2):1; the cationic polyacrylamide (CPAM) has a molecular weight of 12 million Daltons and an ionicity of 30%; and the polydimethyldiallyl ammonium chloride (PDADMAC) has a characteristic viscosity range of 1.0~1.8 dL / g.

[0013] Preferably, the natural polymeric coagulant is a mixture of sodium carboxymethyl cellulose (CMC) and guar gum, wherein the mass ratio of sodium carboxymethyl cellulose (CMC) to guar gum is (1~2):(1~2).

[0014] Preferably, the demulsifier is a mixture of block polyether and sodium fatty alcohol polyoxyethylene ether sulfate (AES), wherein the mass ratio of block polyether to sodium fatty alcohol polyoxyethylene ether sulfate (AES) is (3~5):1.

[0015] Preferably, the synthetic coagulant is a mixture of activated silica and powdered activated carbon, wherein the mass ratio of activated silica to powdered activated carbon is 1:(1~3); the activated silica is obtained by activating water glass with sulfuric acid to a pH of 8~9, and the modulus of the water glass is 3.2; the activated carbon is 300 mesh powder.

[0016] This invention also proposes a method for preparing a silicon powder conditioning agent, comprising the following preparation steps:

[0017] The solid powders of polyaluminum chloride (PAC) and polyferric sulfate (PFS) are mixed and added to water for the first dissolution treatment, followed by standing and aging to obtain an inorganic coagulant slurry.

[0018] The cationic polyacrylamide (CPAM) powder is added to water for a second dissolution treatment to obtain a polyacrylamide solution. The polydimethyldiallyl ammonium chloride (PDADMAC) liquid is added to water and stirred to obtain a polydimethyldiallyl ammonium chloride solution. The polyacrylamide solution and the polydimethyldiallyl ammonium chloride solution are mixed and allowed to stand for aging to obtain an organic polymer solution.

[0019] The sodium carboxymethyl cellulose (CMC), guar gum, block polyether, and sodium fatty alcohol polyoxyethylene ether sulfate (AES) were added to water for a third dissolution treatment to obtain a mixed solution.

[0020] The inorganic coagulant slurry is added to the mixed solution and stirred. Then, the organic polymer solution is added while stirring. After the mixture is completed, the activated silica and powdered activated carbon are added and stirred continuously. After the mixture is completed, it is allowed to stand and mature to obtain the silica powder conditioner.

[0021] Preferably, the first dissolution process is as follows: at a speed of 400 rpm, the mixed polyaluminum chloride (PAC) and polyferric sulfate (PFS) solid powders are added to water, and after all the powders are added, the mixture is stirred for 40 minutes.

[0022] The second dissolution process is as follows: at a speed of 150 rpm, the cationic polyacrylamide (CPAM) powder is added to water at 45°C. After all the powder is added, the speed is increased to 500 rpm and stirring is continued for 2.5 hours.

[0023] Preferably, the third dissolution process is as follows: guar gum and sodium carboxymethyl cellulose (CMC) are added sequentially to water at 65°C at a speed of 250 rpm. After completion, the mixture is kept warm and stirred for 1 hour. Then, the temperature is lowered to 25°C, and block polyether and sodium fatty alcohol polyoxyethylene ether sulfate (AES) are added sequentially while stirring. Stirring is continued for 45 minutes after completion.

[0024] The present invention also proposes an application of silicon powder conditioner in water treatment, comprising: first adding silicon powder conditioner to wastewater containing silicon powder for reaction, and then sending the reacted wastewater into relevant water treatment equipment for treatment;

[0025] The relevant water treatment equipment includes: filters, filter presses, and sedimentation tanks.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) Synergistic demulsification and coagulation: This invention combines a demulsifier with various coagulants and coagulant aids. The demulsifier preferentially breaks down the oil-water interface film, releasing the encapsulated silica powder and eliminating the "colloidal protection" effect of oil on the silica powder surface. Subsequently, inorganic and organic coagulants rapidly neutralize and adsorb the exposed silica powder particles, forming flocs with good settling properties and easy filtration.

[0028] (2) Effective for fine particles: Inorganic coagulant (PAC / PFS) provides positive charge and effectively neutralizes negatively charged fine silica powder; high molecular weight CPAM and strong cationic PDADMAC form long chain bridging and patching effects, specifically capturing fine particles of 1-5μm; natural polymer (CMC / guar gum) further increases the volume and density of flocs, preventing flocs from breaking under shear.

[0029] (3) Improved filtration performance: After using the present invention, the flocs formed in the circulating water are dense and strong, and are not easy to penetrate the filter material during filtration and pressure filtration. The filter cake formed is loose and porous with good dewatering properties, which greatly improves the filtration speed and pressure filtration efficiency and extends the service life of the filter cloth / filter bag. Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0031] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] This invention provides a silicon powder conditioning agent, comprising the following components by mass fraction:

[0036] Inorganic coagulant 20-40%, organic polymer coagulant 5-15%, natural polymer coagulant 3-10%, demulsifier 10-25%, synthetic coagulant 2-8%, balance water.

[0037] The preferred mass fractions of each component are: 30-40% inorganic coagulant, 10-15% organic polymer coagulant, 5-10% natural polymer coagulant aid, 20-25% demulsifier, 6-8% synthetic coagulant aid, and the remainder being water.

[0038] The preferred mass fractions of the components are: 30% inorganic coagulant, 10% organic polymer coagulant, 5% natural polymer coagulant aid, 20% demulsifier, 6% synthetic coagulant aid, and the remainder being water.

[0039] Specifically, the water is preferably deionized water.

[0040] The inorganic coagulant in this invention functions by neutralizing charge and sweeping away the fine silica particles, thereby destabilizing them. The numerous polynuclear hydroxyl complex cations generated after hydrolysis effectively neutralize the negative charge on the silica surface, compressing its electrical double layer and destabilizing it. Simultaneously, the aluminum hydroxide or ferric hydroxide colloids generated during hydrolysis act like a large net, encapsulating and sweeping away the destabilized fine particles, agglomerating them into visible initial micro-flocs, laying the foundation for subsequent flocculation.

[0041] The organic polymer coagulant in this invention functions as a powerful adsorption and bridging agent. Its long polymer chain structure acts like a "rope," with one end adsorbing onto a destabilized silica powder particle and the other end extending into the solution to adsorb another particle, thus bridging multiple particles. This further aggregates the micro-flocs formed by the inorganic coagulant into large, dense flocs with fast settling speeds and easy mechanical dehydration, which is crucial for retaining submicron-sized fine particles.

[0042] The natural polymeric coagulants in this invention function as floc structure modifiers and thickeners. They increase the viscosity of the aqueous phase, slowing down the settling rate of the formed flocs, thus providing more time and space for floc growth. Simultaneously, their long-chain molecules can penetrate into the floc interior, enhancing the floc's toughness and mechanical strength, preventing it from breaking under shear force, and improving the floc's pore structure, making it easier to dewater during filter press and forming a drier, harder filter cake.

[0043] The demulsifier in this invention serves to solve the problem of water emulsification caused by the presence of oil. It possesses stronger surface activity and interfacial aggregation ability than emulsifiers, enabling it to penetrate and disrupt the emulsifier interfacial film surrounding oil droplets, achieving three-phase separation of oil, water, and solids (silica powder). This process releases the silica powder encased in the oil film, re-exposing its surface so that it can be effectively captured by subsequent coagulants. This is a prerequisite and crucial step in treating emulsified silica-containing wastewater.

[0044] The synthetic coagulant in this invention functions as follows: activated silica, a negatively charged colloid, can mutually promote coagulation with positively charged inorganic hydrolysis products, forming a heavier and denser floc skeleton, significantly accelerating sedimentation. Powdered activated carbon, with its large specific surface area and adsorption capacity, can not only adsorb residual trace amounts of dissolved organic matter and oil in the water, but also act as a coagulation nucleus for fine particles, further improving water clarity.

[0045] In this invention, the inorganic coagulant is a mixture of polyaluminum chloride (PAC) and polyferric sulfate (PFS), wherein the mass ratio of polyaluminum chloride (PAC) to polyferric sulfate (PFS) is preferably (1~3):1, the basicity of polyaluminum chloride (PAC) is preferably 80%, and the total iron content of polyferric sulfate (PFS) is preferably 19%.

[0046] Understandably, the combination of polyaluminum chloride (PAC) with a basicity of 80% and polyferric sulfate (PFS) with a total iron content of 19% at a mass ratio of (1~3):1 fully leverages the synergistic advantages of PAC's strong charge neutralization ability and rapid flocculation reaction, and the dense flocs and fast settling speed generated by PFS. The high basicity of PAC can quickly neutralize the negative charge on the surface of silica powder, destabilizing it, while the high purity of PFS, through the strong netting and sweeping effect of its hydrolysis products, together with PAC, constructs a highly efficient coagulation system from micro-charge neutralization to macro-floc growth, thereby forming a more effective coagulation effect on the fine particles in the emulsified silica-containing wastewater and significantly improving the subsequent solid-liquid separation efficiency.

[0047] In this invention, the organic polymer coagulant is a mixture of cationic polyacrylamide (CPAM) and polydimethyldiallylammonium chloride (PDADMAC), wherein the mass ratio of cationic polyacrylamide (CPAM) to polydimethyldiallylammonium chloride (PDADMAC) is preferably (1~2):1; the molecular weight of the cationic polyacrylamide (CPAM) is preferably 12 million Daltons, and the degree of ionization is preferably 30%; the characteristic viscosity range of the polydimethyldiallylammonium chloride (PDADMAC) is preferably 1.0~1.8 dL / g.

[0048] Understandably, this invention combines high molecular weight (12 million Daltons), moderate ionicity (30%) cationic polyacrylamide (CPAM) with polydimethyldiallyl ammonium chloride (PDADMAC) in a mass ratio of (1~2):1, combining the long-chain bridging advantage of CPAM with the strong charge neutralization and rapid diffusion characteristics of PDADMAC. The high molecular weight CPAM can effectively adsorb and link multiple micro-flocs formed by inorganic coagulants, constructing a large and tough floc skeleton to improve dewatering performance, while the strong cationic PDADMAC can preferentially and rapidly neutralize the surface charge of silica powder particles affected by oil or emulsifiers, completely destroying their stability. The two work together to ensure the formation of dense, stable and easily separable flocs in complex wastewater systems, thereby significantly improving filtration and pressure filtration efficiency and ensuring the quality of effluent.

[0049] In this invention, the natural polymeric coagulant is a mixture of sodium carboxymethyl cellulose (CMC) and guar gum, wherein the preferred mass ratio of sodium carboxymethyl cellulose (CMC) to guar gum is (1~2):(1~2).

[0050] Understandably, this invention combines sodium carboxymethyl cellulose (CMC) and guar gum in a balanced mass ratio of (1~2):(1~2), combining the excellent suspension stability and film-forming properties of CMC with the strong thickening and hydration capabilities of guar gum. The long-chain molecules of CMC can effectively encapsulate and stabilize the formed flocs, preventing them from breaking, while guar gum can rapidly increase the viscosity of the aqueous phase, slow down sedimentation, and provide more space and time for floc growth. The two work synergistically in this specific ratio to jointly construct an ideal floc with good toughness, dense structure, and suitable sedimentation rate, thereby significantly enhancing the stability of the flocs under shear force and improving their dewatering performance during the pressure filtration process, ultimately ensuring the thoroughness of solid-liquid separation and the clarity of the effluent.

[0051] In this invention, the demulsifier is a mixture of block polyether and sodium fatty alcohol polyoxyethylene ether sulfate (AES), wherein the mass ratio of block polyether to sodium fatty alcohol polyoxyethylene ether sulfate (AES) is (3~5):1.

[0052] Specifically, the block polyether is preferably PE10400, and the molecular structure of PE10400 is a polyoxypropylene-polyoxyethylene-polyoxypropylene (PO-EO-PO) triblock copolymer.

[0053] It is understood that this invention, by compounding block polyether with sodium fatty alcohol polyoxyethylene ether sulfate (AES) at a relatively high mass ratio of (3~5):1, fully leverages the advantages of block polyether as the main demulsifier in its efficient penetration and displacement capabilities at the oil-water interface, and the excellent penetration, dispersion, and synergistic demulsification effects of AES as an anionic surfactant. This ratio ensures that block polyether molecules can preferentially and fully adsorb at the oil-water interface, effectively disrupting the stability of the emulsion through strong interfacial competition and film deformation effects. Meanwhile, an appropriate amount of AES can synergistically enhance the penetration and stripping of emulsified oil droplets, while avoiding the formation of new micelles or the production of emulsion-stabilizing reactions due to excessive addition. This achieves efficient and rapid demulsification of trace amounts of lubricating oil and other oil contaminants in silica-containing wastewater, creating the prerequisite for effectively capturing the released silica particles in the subsequent coagulation step.

[0054] In this invention, the synthetic coagulant is a mixture of activated silica and powdered activated carbon, wherein the mass ratio of activated silica to powdered activated carbon is 1:(1~3); the activated silica is obtained by activating water glass with sulfuric acid to a pH of 8~9, and the modulus of the water glass is 3.2; the activated carbon is 300 mesh powder.

[0055] Understandably, this invention combines activated silica (pH 8-9, activated by water glass with a modulus of 3.2) with 300-mesh powdered activated carbon at a mass ratio of 1:(1-3). This combination integrates the flocculant-building ability of activated silica with the adsorption and purification function of powdered activated carbon. The moderately polymerized activated silica colloid acts as a negatively charged auxiliary coagulant, which can mutually promote coagulation with the positively charged aluminum / iron hydrolysis products, generating denser and heavier floc cores and significantly accelerating the settling speed. The high-fineness powdered activated carbon not only adsorbs residual dissolved organic matter and trace amounts of oil in the water with its huge specific surface area, but also acts as a micro-core and weight carrier, embedding and strengthening the floc structure. The two work synergistically at this ratio to achieve simultaneous improvement in deep water purification and flocculation efficiency, ensuring the high clarity of the final effluent.

[0056] This invention also provides a method for preparing a silicon powder conditioning agent, comprising the following preparation steps:

[0057] The solid powders of polyaluminum chloride (PAC) and polyferric sulfate (PFS) are mixed and added to water for the first dissolution treatment, followed by standing and aging to obtain an inorganic coagulant slurry.

[0058] The cationic polyacrylamide (CPAM) powder is added to water for a second dissolution treatment to obtain a polyacrylamide solution. The polydimethyldiallyl ammonium chloride (PDADMAC) liquid is added to water and stirred to obtain a polydimethyldiallyl ammonium chloride solution. The polyacrylamide solution and the polydimethyldiallyl ammonium chloride solution are mixed and allowed to stand for aging to obtain an organic polymer solution.

[0059] The sodium carboxymethyl cellulose (CMC), guar gum, block polyether, and sodium fatty alcohol polyoxyethylene ether sulfate (AES) were added to water for a third dissolution treatment to obtain a mixed solution.

[0060] The inorganic coagulant slurry is added to the mixed solution and stirred. Then, the organic polymer solution is added while stirring. After the mixture is completed, the activated silica and powdered activated carbon are added and stirred continuously. After the mixture is completed, it is allowed to stand and mature to obtain the silica powder conditioner.

[0061] Specifically, when mixing the polyaluminum chloride (PAC) and polyferric sulfate (PFS) solid powders, a mixer is used to mix at low speed for 20 minutes until the color is uniform.

[0062] Specifically, the preferred settling and maturation time for preparing inorganic coagulant slurry is 2 hours; the preferred settling and maturation time for preparing organic polymer solution is 4 hours; and the preferred settling and maturation time for finally preparing silica powder conditioner is 24 hours.

[0063] Specifically, the silicon powder conditioning agent has a solid content of 25-40% and a pH value of 3.5-5.5 at 25°C.

[0064] In this invention, the first dissolution process is as follows: at a speed of 400 rpm, the mixed polyaluminum chloride (PAC) and polyferric sulfate (PFS) solid powders are added to water, and after all the powders are added, the mixture is stirred for 40 minutes.

[0065] Specifically, at a speed of 400 rpm, the mixed polyaluminum chloride (PAC) and polyferric sulfate (PFS) solid powders were slowly added to a portion (30% of the total amount) of deionized water, and the stirring speed was controlled at 400 rpm for 40 minutes.

[0066] Understandably, adding solid powder to a limited amount of water (30% of the total volume) and continuously stirring at a medium-high speed of 400 rpm for 40 minutes aims to create a high-concentration pre-hydrolysis reaction environment. Under these conditions, the intense fluid shear force can thoroughly break up powder clumps, ensuring thorough and uniform dissolution. At the same time, the precisely controlled stirring intensity and time ensure that the active hydroxyl polymers of PAC and PFS are fully formed and stabilized, laying the molecular structural foundation for subsequent efficient charge neutralization and trapping effects. It also effectively avoids the aging and deactivation of hydrolysis products due to excessive shearing or precipitation caused by prolonged standing, thus ensuring the high reactivity and storage stability of the inorganic coagulant slurry. This provides a key guarantee for the uniform mixing with other components and the overall efficacy of the drug.

[0067] In this invention, the second dissolution process is as follows: the cationic polyacrylamide (CPAM) powder is added to water at 45°C at a speed of 150 rpm. After all the powder is added, the speed is increased to 500 rpm and stirring is continued for 2.5 hours.

[0068] Specifically, at a speed of 150 rpm, the cationic polyacrylamide (CPAM) powder is slowly and evenly sprinkled into 20% of the total amount of deionized water at a temperature of 45°C. After the addition is complete, the stirring speed is increased to 500 rpm and stirring is continued for 2.5 hours until a colorless, transparent, and fish-eye-free viscous colloidal solution is formed.

[0069] Understandably, by precisely controlling the dissolving water temperature at 45℃ and slowly adding CPAM powder at a gentle stirring speed of 150 rpm in the initial stage, the aim is to create an optimal dissolution environment that facilitates the slow unfolding of polymer chains and avoids the formation of "fish eyes." Subsequently, the stirring speed is increased to 450 rpm and stirred continuously for 2.5 hours. These optimized parameters provide sufficient shear force to accelerate dissolution and ensure solution homogeneity while effectively avoiding polymer chain breakage and degradation caused by excessive and vigorous stirring. This maximizes the protection of the molecular weight integrity of CPAM, which is up to 12 million Daltons, and the bridging ability of the long polymer chains, ensuring that the final colloidal solution B1 has uniform, stable, and highly efficient flocculation activity.

[0070] In this invention, the third dissolution process is as follows: Guar gum and sodium carboxymethyl cellulose (CMC) are added sequentially to water at 65°C at a speed of 250 rpm. After completion, the mixture is kept warm and stirred for 1 hour. Then, the temperature is lowered to 25°C, and block polyether and sodium fatty alcohol polyoxyethylene ether sulfate (AES) are added sequentially while stirring. Stirring is continued for 45 minutes after completion.

[0071] Specifically, in a reactor equipped with a heating function, the remaining deionized water is added and heated to 65°C. Guar gum and sodium carboxymethyl cellulose (CMC) are added sequentially at a speed of 250 rpm. After completion, the reactor is kept warm and stirred for 1 hour. The reactor temperature is then lowered to room temperature (25°C), and block polyether and sodium fatty alcohol polyoxyethylene ether sulfate (AES) are added sequentially while stirring. Stirring is continued for 45 minutes.

[0072] Understandably, by setting a heating condition of 65℃ and gentle stirring at 250 rpm, ideal hydration temperature and moderate shear force were provided for guar gum and CMC, ensuring that their polymer chains rapidly expand and fully swell to form a structurally stable colloidal base liquid. Subsequently, the system was cooled to 25℃ before adding block polyether and AES in sequence. This precise operation of temperature zones and stages not only avoided structural damage and efficiency loss of the surfactant demulsifying component due to high temperature, but also ensured that the demulsifier molecules could be fully dispersed at the appropriate temperature and maintain their interfacial activity. Ultimately, the complete activation of the natural polymer coagulant and the complete preservation of the high efficiency performance of the demulsifier were achieved, laying a solid foundation for subsequent compounding with inorganic coagulants to exert synergistic demulsification-flocculation effects.

[0073] The present invention also provides an application of silicon powder conditioner in water treatment, comprising: first adding silicon powder conditioner to wastewater containing silicon powder for reaction, and then sending the reacted wastewater into relevant water treatment equipment for treatment;

[0074] The relevant water treatment equipment includes: filters, filter presses, and sedimentation tanks.

[0075] Specifically, the application method of the silica powder conditioner of the present invention is as follows: The conditioner is added before the silica powder-containing water enters solid-liquid separation equipment such as a bag filter / cartridge filter or plate and frame filter press. The dosage is 10-500 ppm (volume ratio) of the total wastewater volume. A static mixer or mechanical stirring is used to ensure rapid and uniform mixing with the wastewater. After a reaction time of approximately 1-3 minutes, the mixture can be introduced into the subsequent separation equipment.

[0076] It is understandable that water containing silica powder is first treated with a silica powder conditioner, and then it enters relevant water treatment equipment, including but not limited to filters, filter presses, sedimentation tanks and other solid-liquid separation equipment, to achieve better silica powder separation effect and improve the water quality of the separated water.

[0077] Example 1

[0078] I. Weighing of the silicon powder conditioning agent components:

[0079] 30 parts inorganic coagulant (including 20 parts PAC and 10 parts PFS), 10 parts organic polymer coagulant (including 6 parts CPAM and 4 parts PDADMAC), 5 parts natural polymer coagulant aid (including 2.5 parts CMC and 2.5 parts guar gum), 20 parts demulsifier (including 16 parts block polyether PE10400 and 4 parts AES), 6 parts synthetic coagulant aid (including 2 parts activated silica and 4 parts 300-mesh powdered activated carbon), and 30 parts deionized water.

[0080] II. Preparation method of silicon powder conditioning agent:

[0081] S1. Mix 20 parts PAC and 10 parts PFS in a dry environment at low speed in a mixer for 20 minutes until the color is uniform. At a speed of 400 rpm, slowly add the mixed polyaluminum chloride (PAC) and polyferric sulfate (PFS) solid powder to 9 parts deionized water, control the stirring speed at 400 rpm, stir for 40 minutes, and let stand for 2 hours to mature to obtain inorganic coagulant slurry.

[0082] S2. Heat 6 parts of deionized water to 45°C and add it to a dissolving tank. Then, slowly and evenly sprinkle 6 parts of CPAM into the deionized water at 150 rpm. After the addition is complete, increase the stirring speed to 500 rpm and continue stirring for 2.5 hours until a colorless, transparent, and fish-eye-free viscous colloidal solution is formed, thus obtaining a polyacrylamide solution. Heat 6 parts of deionized water to 45°C and add it to another dissolving tank. Add 4 parts of PDADMAC to the tank at 250 rpm to obtain a polydimethyldiallyl ammonium chloride solution. Stir the polyacrylamide solution and the polydimethyldiallyl ammonium chloride solution at 250 rpm for 30 minutes to obtain an organic polymer solution.

[0083] S3. In a reactor equipped with a heating function, add the remaining 9 parts of deionized water and heat to 65°C. Start stirring and add 2.5 parts of guar gum and 2.5 parts of sodium carboxymethyl cellulose (CMC) sequentially at a speed of 250 rpm. After completion, keep the reactor at this temperature and stir for 1 hour. Then, lower the reactor temperature to room temperature (25°C) and add 16 parts of block polyether PE10400 and 4 parts of fatty alcohol polyoxyethylene ether sulfate (AES) sequentially while stirring. Continue stirring for 45 minutes to obtain a mixed solution.

[0084] S4. The inorganic coagulant slurry is slowly added to the mixed solution while stirring at 350 rpm, with the addition time controlled at 18 minutes. After the addition is complete, stirring is continued for 20 minutes. Then, the organic polymer solution is slowly added while stirring, with the addition time controlled at 15 minutes. After completion, 2 parts of activated silica and 4 parts of 300-mesh activated carbon powder are added. The stirring speed is increased to 600 rpm and stirring is continued for 50 minutes. Then, stirring is stopped and the mixture is allowed to stand for 24 hours to mature, thus obtaining the silica powder conditioner.

[0085] Example 2

[0086] I. Weighing of the silicon powder conditioning agent components:

[0087] 40 parts inorganic coagulant (including 20 parts PAC and 20 parts PFS), 5 parts organic polymer coagulant (including 2.5 parts CPAM and 2.5 parts PDADMAC), 3 parts natural polymer coagulant aid (including 1 part CMC and 2 parts guar gum), 10 parts demulsifier (including 7.5 parts block polyether PE10400 and 2.5 parts AES), 2 parts synthetic coagulant aid (including 1 part activated silica and 1 part 300-mesh powdered activated carbon), and 40 parts deionized water.

[0088] II. Preparation method of silicon powder conditioning agent:

[0089] S1. Mix 20 parts PAC and 20 parts PFS in a dry environment at low speed in a mixer for 20 minutes until the color is uniform. At a speed of 400 rpm, slowly add the mixed polyaluminum chloride (PAC) and polyferric sulfate (PFS) solid powder to 12 parts deionized water, control the stirring speed at 400 rpm, stir for 40 minutes, and let stand for 2 hours to mature to obtain inorganic coagulant slurry.

[0090] S2. Heat 8 parts of deionized water to 45°C and add it to a dissolving tank. Then, slowly and evenly sprinkle 2.5 parts of CPAM into the deionized water at 150 rpm. After the addition is complete, increase the stirring speed to 500 rpm and continue stirring for 2.5 hours until a colorless, transparent, and fish-eye-free viscous colloidal solution is formed, thus obtaining a polyacrylamide solution. Heat 8 parts of deionized water to 45°C and add it to another dissolving tank. Add 2.5 parts of PDADMAC to the tank at 250 rpm to obtain a polydimethyldiallyl ammonium chloride solution. Stir the polyacrylamide solution and the polydimethyldiallyl ammonium chloride solution at 250 rpm for 30 minutes to obtain an organic polymer solution.

[0091] S3. In a reactor equipped with a heating function, add the remaining 12 parts of deionized water and heat to 65°C. Start stirring and add 2 parts of guar gum and 1 part of sodium carboxymethyl cellulose (CMC) at 250 rpm. After completion, keep the reactor at this temperature and stir for 1 hour. Then, lower the reactor temperature to room temperature (25°C) and add 7.5 parts of block polyether PE10400 and 2.5 parts of fatty alcohol polyoxyethylene ether sulfate (AES) while stirring. Continue stirring for 45 minutes to obtain a mixed solution.

[0092] S4. The inorganic coagulant slurry is slowly added to the mixed solution while stirring at 350 rpm, with the addition time controlled at 18 minutes. After the addition is complete, stirring is continued for 20 minutes. Then, the organic polymer solution is slowly added while stirring, with the addition time controlled at 15 minutes. After completion, 1 part of activated silica and 1 part of 300-mesh activated carbon powder are added. The stirring speed is increased to 600 rpm and stirring is continued for 50 minutes. Then, stirring is stopped and the mixture is allowed to stand for 24 hours to mature, thereby obtaining the silica powder conditioner.

[0093] Example 3

[0094] I. Weighing of the silicon powder conditioning agent components:

[0095] 20 parts inorganic coagulant (including 15 parts PAC and 5 parts PFS), 15 parts organic polymer coagulant (including 10 parts CPAM and 5 parts PDADMAC), 10 parts natural polymer coagulant aid (including 6.6 parts CMC and 3.4 parts guar gum), 25 parts demulsifier (including 20.8 parts block polyether PE10400 and 4.2 parts AES), 8 parts synthetic coagulant aid (including 2 parts activated silica and 6 parts 300-mesh powdered activated carbon), and 22 parts deionized water.

[0096] II. Preparation method of silicon powder conditioning agent:

[0097] S1. Mix 15 parts PAC and 5 parts PFS in a dry environment at low speed in a mixer for 20 minutes until the color is uniform. At a speed of 400 rpm, slowly add the mixed polyaluminum chloride (PAC) and polyferric sulfate (PFS) solid powder to 6.6 parts deionized water, control the stirring speed at 400 rpm, stir for 40 minutes, and let stand for 2 hours to mature to obtain inorganic coagulant slurry.

[0098] S2. Heat 4.4 parts of deionized water to 45°C and add it to a dissolving tank. Then, slowly and evenly sprinkle 10 parts of CPAM into the deionized water at 150 rpm. After the addition is complete, increase the stirring speed to 500 rpm and continue stirring for 2.5 hours until a colorless, transparent, and fish-eye-free viscous colloidal solution is formed, thus obtaining a polyacrylamide solution. Heat 4.4 parts of deionized water to 45°C and add it to another dissolving tank. Add 5 parts of PDADMAC to the tank at 250 rpm to obtain a polydimethyldiallyl ammonium chloride solution. Stir the polyacrylamide solution and the polydimethyldiallyl ammonium chloride solution at 250 rpm for 30 minutes to obtain an organic polymer solution.

[0099] S3. In a reactor equipped with a heating function, add the remaining 6.6 parts of deionized water and heat to 65°C. Start stirring and add 3.4 parts of guar gum and 6.6 parts of sodium carboxymethyl cellulose (CMC) sequentially at a speed of 250 rpm. After completion, keep the reactor at this temperature and stir for 1 hour. Then, lower the reactor temperature to room temperature (25°C) and add 20.8 parts of block polyether PE10400 and 4.2 parts of fatty alcohol polyoxyethylene ether sulfate (AES) sequentially while stirring. Continue stirring for 45 minutes to obtain a mixed solution.

[0100] S4. The inorganic coagulant slurry is slowly added to the mixed solution while stirring at 350 rpm, with the addition time controlled at 18 minutes. After the addition is complete, stirring is continued for 20 minutes. Then, the organic polymer solution is slowly added while stirring, with the addition time controlled at 15 minutes. After completion, 2 parts of activated silica and 6 parts of 300-mesh activated carbon powder are added. The stirring speed is increased to 600 rpm and stirring is continued for 50 minutes. Then, stirring is stopped and the mixture is allowed to stand for 24 hours to mature, thus obtaining the silica powder conditioner.

[0101] Effect test

[0102] Test water sample: Simulated silicon rod cutting wastewater. 200-mesh high-purity silicon powder was added to deionized water to simulate actual working conditions, preparing a suspension with an initial silicon powder concentration of 500 mg / L. To simulate emulsification, 50 mg / L of mineral oil (ISOVG 32 hydraulic oil) and a small amount of nonionic surfactant (Tween-80) were also added. After treatment with a high-speed shear emulsifier (10000 rpm, 5 minutes), a stable milky white emulsified silicon-containing wastewater was formed. The initial turbidity was ~350 NTU.

[0103] Test reagents

[0104] Experimental Example: Silicon Powder Conditioner Prepared in Example 1 of this Invention

[0105] Comparative Example 1: Only polyaluminum chloride (PAC) was used, with a concentration comparable to the total content of inorganic coagulants in Example 1 of this invention.

[0106] Comparative Example 2: A combination of PAC and cationic PAM (CPAM) was used, which is a commonly used process.

[0107] Testing equipment: six-unit programmable coagulation experimental mixer, laser particle size analyzer, multi-parameter water quality analyzer (for turbidity and pH), ultraviolet spectrophotometer (for oil content), vacuum filtration device, Buchner funnel, 0.45μm microporous filter membrane, electronic balance, and drying oven.

[0108] Test steps:

[0109] Three parallel experimental groups were set up:

[0110] Blank control group: No drugs were added.

[0111] Comparative Example 1: PAC was added at a dosage of 200 mg / L.

[0112] Comparative Group 2: PAC (150 mg / L) + CPAM (2 mg / L) were added.

[0113] Experimental group: The conditioner prepared in Example 1 of this invention was added, with a total addition amount of 300 mg / L.

[0114] S1. Take 1L of the simulated wastewater into each beaker and place them on the coagulation experiment mixer.

[0115] S2. Start rapid stirring (200 rpm), add the corresponding reagent simultaneously, continue for 2 minutes to ensure uniform mixing, then switch to slow stirring (40 rpm) for 10 minutes to promote floc growth, stop stirring and let stand and settle for 15 minutes.

[0116] S3. At 1, 3, 5, 10 and 15 minutes after the settling begins, use a camera to record the morphology of the flocs and the sedimentation interface in each beaker. After the settling is completed, collect the supernatant 2 cm below the liquid surface for water quality analysis.

[0117] S4. Vacuum filter the entire mud-water mixture after settling (using a 0.45μm filter membrane), record the filtration time, and dry the filter cake at 105℃ to constant weight. Weigh the filter cake and calculate its moisture content.

[0118] The test results are shown in Table 1:

[0119] Table 1 Test Results

[0120]

[0121] As shown in Table 1, regarding the demulsification and flocculation effects: Comparative Example 1 (PAC) had limited demulsification effect, resulting in small flocs and a still relatively turbid supernatant after settling, indicating incomplete removal of silica fume and oil. Comparative Example 2 (PAC+CPAM), while improving flocculation, lacked sufficient capacity to handle emulsified oil, leading to loose floc structure containing oil, which affected subsequent dehydration and final water quality. In contrast, the experimental group's demulsifier and coagulation system exhibited a significant synergistic effect; the demulsifier preferentially demulsified, releasing the oil-encapsulated silica fume, allowing the subsequent coagulant to fully function, resulting in large, dense flocs with rapid settling and an extremely clear supernatant.

[0122] Regarding the water quality improvement effect: After treatment with the silica powder conditioner prepared in Example 1 of this invention, the turbidity of the water is <5 NTU, the silica powder content is <20 mg / L, and the oil content is <8 mg / L. All indicators are far superior to the comparative example, and the water quality requirements for recycled water (silica powder ≤50 ppm) are consistently met and exceeded.

[0123] Regarding filtration and dehydration performance: the filtration time of the silica powder conditioner in Example 1 of this invention is only 45 seconds, far lower than the 120 seconds and 180 seconds of the comparative examples. This indicates that the floc structure improves the filtration channel, greatly enhancing filtration efficiency and effectively handling high-load filtration operations. Simultaneously, the filter cake moisture content after treatment with the silica powder conditioner prepared in Example 1 of this invention is reduced to 58%, far lower than the 72% and 78% of the comparative examples. This not only proves that the demulsification and flocculation effects improve the hydrophilicity of the flocs, but also signifies a reduction in solid waste generation after pressure filtration, lower treatment costs, and improved operating efficiency.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A silicon powder conditioning agent, characterized in that, The components include the following parts by mass: Inorganic coagulant 20-40%, organic polymer coagulant 5-15%, natural polymer coagulant aid 3-10%, demulsifier 10-25%, synthetic coagulant aid 2-8%, balance water; The inorganic coagulant is a mixture of polyaluminum chloride (PAC) and polyferric sulfate (PFS), wherein the mass ratio of polyaluminum chloride (PAC) to polyferric sulfate (PFS) is (1~3):1, the basicity of polyaluminum chloride (PAC) is 80%, and the total iron content of polyferric sulfate (PFS) is 19%. The organic polymer coagulant is a mixture of cationic polyacrylamide (CPAM) and polydimethyldiallyl ammonium chloride (PDADMAC), wherein the mass ratio of cationic polyacrylamide (CPAM) to polydimethyldiallyl ammonium chloride (PDADMAC) is (1~2):1; the cationic polyacrylamide (CPAM) has a molecular weight of 12 million Daltons and an ionicity of 30%; the polydimethyldiallyl ammonium chloride (PDADMAC) has a characteristic viscosity range of 1.0~1.8 dL / g; The natural polymeric coagulant is a mixture of sodium carboxymethyl cellulose (CMC) and guar gum, wherein the mass ratio of sodium carboxymethyl cellulose (CMC) to guar gum is (1~2):(1~2). The demulsifier is a mixture of block polyether and sodium fatty alcohol polyoxyethylene ether sulfate (AES), wherein the mass ratio of block polyether to sodium fatty alcohol polyoxyethylene ether sulfate (AES) is (3~5):1; The synthetic coagulant is a mixture of activated silica and powdered activated carbon, wherein the mass ratio of activated silica to powdered activated carbon is 1:(1~3); the activated silica is obtained by activating water glass with sulfuric acid to a pH of 8~9, and the modulus of the water glass is 3.2; the activated carbon is 300 mesh powder.

2. A method for preparing the silicon powder conditioning agent as described in claim 1, characterized in that, The preparation steps include the following: The solid powders of polyaluminum chloride (PAC) and polyferric sulfate (PFS) are mixed and added to water for the first dissolution treatment, followed by standing and aging to obtain an inorganic coagulant slurry. The cationic polyacrylamide (CPAM) powder is added to water for a second dissolution treatment to obtain a polyacrylamide solution. The polydimethyldiallyl ammonium chloride (PDADMAC) liquid is added to water and stirred to obtain a polydimethyldiallyl ammonium chloride solution. The polyacrylamide solution and the polydimethyldiallyl ammonium chloride solution are mixed and allowed to stand for aging to obtain an organic polymer solution. The sodium carboxymethyl cellulose (CMC), guar gum, block polyether, and sodium fatty alcohol polyoxyethylene ether sulfate (AES) were added to water for a third dissolution treatment to obtain a mixed solution. The inorganic coagulant slurry is added to the mixed solution and stirred. Then, the organic polymer solution is added while stirring. After the mixture is completed, the activated silica and powdered activated carbon are added and stirred continuously. After the mixture is completed, it is allowed to stand and mature to obtain the silica powder conditioner.

3. The method for preparing the silicon powder conditioning agent according to claim 2, characterized in that, The first dissolution process is as follows: at a speed of 400 rpm, the mixed polyaluminum chloride (PAC) and polyferric sulfate (PFS) solid powders are added to water, and after all the powders are added, the mixture is stirred for 40 minutes. The second dissolution process is as follows: at a speed of 150 rpm, the cationic polyacrylamide (CPAM) powder is added to water at 45°C. After all the powder is added, the speed is increased to 500 rpm and stirring is continued for 2.5 hours.

4. The method for preparing the silicon powder conditioning agent according to claim 3, characterized in that, The third dissolution process is as follows: Guar gum and sodium carboxymethyl cellulose (CMC) are added sequentially to water at 65°C at a speed of 250 rpm. After completion, the mixture is kept warm and stirred for 1 hour. Then, the temperature is lowered to 25°C, and block polyether and sodium fatty alcohol polyoxyethylene ether sulfate (AES) are added sequentially while stirring. Stirring is continued for 45 minutes.

5. An application of the silicon powder conditioner as described in claim 1 in water treatment, characterized in that, First, a silicon powder conditioner is added to the wastewater containing silicon powder to react, and then the wastewater after the reaction is sent to relevant water treatment equipment for treatment. The relevant water treatment equipment includes: filters, filter presses, and sedimentation tanks.

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