A grey water dispersant and a method of making the same

Abstract

The present application relates to coal chemical water treatment technical field, disclose a kind of grey water dispersant and its preparation method, method includes: preparation contains polyhydroxy glycosyl derivative, inorganic-organic hybrid chelating agent, trace fluoride inhibitor composite dispersant composition;Aluminosilicate is activated with alkali and silane coupling agent surface modification preparation hybrid chelating agent;Using mild condition ultrasonic pretreatment broken silicon scale agglomerate;Add composite dispersant to achieve multi-point chelation and polymerization inhibition;Subsequent fluoride capture and biological enhancement wastewater treatment.The present application is through the ortho polyhydroxy structure of glycosyl derivative to the multi-point chelation of high polymer silicic acid, the low COD efficient chelation of hybrid chelating agent, the selective attack of fluoride to silicon-oxygen bond, the synergy of ultrasonic physical crushing and chemical dispersion and so on Innovative technology, control rate of high polymer silicic acid is increased to more than 85% from the prior art 40%, while significantly reducing environmental burden and processing cost.

Description

Technical Field

[0001] This invention relates to the field of coal chemical water treatment technology, and more specifically, to an ash water dispersant and its preparation method. Background Technology

[0002] During the gasification process, the silica content in the ash water can reach over 500 ppm. Under high temperature (120-180℃) and high alkalinity (pH 9-12) conditions, monomeric silica easily undergoes condensation polymerization to form highly polymerized silica such as trisilicic acid and tetrasilicic acid, which then deposit to form a dense silica scale layer.

[0003] Existing ash water dispersants mainly use sulfonic acid copolymers as the main component. This technology has the following problems: First, it has insufficient chelating ability for high polysilicic acid, with a low chelation constant. When the silicon content exceeds 500 ppm, the control rate is only 40%. Second, the dispersant has difficulty penetrating into the interior of dense silica scale agglomerates with a particle size of 10-50 μm. Third, there is a lack of effective means to inhibit the polymerization reaction of silicic acid. Fourth, traditional organic dispersants contribute a high COD, increasing the burden on wastewater treatment. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an ash water dispersant and its preparation method.

[0005] A method for preparing an ash water dispersant includes the following steps:

[0006] Step 1: Preparation of inorganic-organic hybrid chelating agents:

[0007] Aluminosilicate is activated by alkali treatment with sodium hydroxide solution at 80-100℃ for 2-4 hours, washed until neutral and dried to obtain activated aluminosilicate; the activated aluminosilicate is dispersed in anhydrous ethanol, a silane coupling agent is added and refluxed at 60-80℃ for 4-6 hours under nitrogen protection, and the mixture is separated and purified to obtain a hybrid chelating agent.

[0008] Step 2: Preparation of the composite dispersant composition:

[0009] Prepare a composite dispersant composition by mixing 40-70 parts by weight of a chelating component, 5-15 parts by weight of a polymerization inhibitor, 20-40 parts by weight of a dispersion stabilizing component, and 5-15 parts by weight of an auxiliary functional component. The chelating component contains a polyhydroxy sugar derivative and a hybrid chelating agent prepared in step 1. The polymerization inhibitor contains a fluoride.

[0010] Step 3: Gentle ultrasound pretreatment:

[0011] Add an antioxidant to the ash water, treat it with ultrasound at a power density of 0.3-0.5 W / mL for 1-2 minutes, and then add the composite dispersant composition prepared in step 2.

[0012] Preferably, the aluminosilicate is selected from 13X molecular sieve zeolite or kaolin, and the silane coupling agent is selected from aminopropyltriethoxysilane or mercaptopropyltrimethoxysilane, with an amount of 5-15% of the mass of the aluminosilicate.

[0013] Preferably, the chelating component comprises: 15-30 parts of a nitrogen-containing heterocyclic chelating agent, 20-40 parts of a polyhydroxy glycosyl derivative, and 5-15 parts of a hybrid chelating agent; the polyhydroxy glycosyl derivative is selected from sodium gluconate, D-sorbitol, or hydroxyethyl cellulose ether.

[0014] Preferably, the polymerization inhibitory component comprises: 3-8 parts of sodium fluorosilicate or sodium fluoride, and 2-7 parts of lattice distortion agent; the lattice distortion agent is selected from 1-hydroxyethylidene-1,1-diphosphonic acid or sodium polyaspartate.

[0015] Preferably, the dispersion stabilizing component comprises: 15-25 parts of maleic acid-acrylic acid-sulfonic acid terpolymer and 5-15 parts of polycarboxylic acid dispersant.

[0016] Preferably, the antioxidant is sodium sulfite or ascorbic acid, and the concentration is 10-20 mg / L; the frequency of the ultrasonic treatment is 20-40 kHz.

[0017] Preferably, the concentration of the composite dispersant composition is 60-120 mg / L, and it is prepared into an aqueous solution with a mass fraction of 20%-30% by wet dosing.

[0018] Preferably, the process also includes a fluoride ion capture step: adding lime slurry to the treated ash water and converting fluoride ions into calcium fluoride precipitate through chemical precipitation, thereby reducing the fluoride concentration to below 5 mg / L.

[0019] Preferably, the amount of lime slurry added is 1.1-1.2 times the stoichiometry of fluoride ions, the pH of the precipitation reaction is controlled at 8.5-9.5, and the reaction temperature is 60-80℃.

[0020] A ash water dispersant prepared by the above method comprises a polyhydroxy sugar derivative, an inorganic-organic hybrid chelating agent, a fluoride polymerization inhibitor, a dispersing stabilizer, and an auxiliary functional agent, achieving a scale inhibition rate of over 85% for high-polysilicic acid.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. Significantly improved scale inhibition performance: The scale inhibition rate of silica scale has increased from 32.4% in the existing technology to 78.9%, a relative improvement of 143.5%. The chelation constant has increased dramatically from lgK=4.18 in traditional chelating agents to lgK=6.82, an increase of 43.7 times, which is more than 1.6 orders of magnitude.

[0023] 2. Significantly improved environmental friendliness: Through inorganic-organic hybrid chelating agent technology, the COD contribution is reduced from 51.8 mg / L in the traditional formula to 27.6 mg / L, a reduction rate of 46.7%; the COD contribution of the pure hybrid chelating agent is only 2.4 mg / L, a reduction rate of 95.4%. The fluoride ion removal rate is 82.7%, and the effluent meets the GB8978 Class I discharge standard.

[0024] 3. Significant synergistic effect: Ultrasonic treatment reduces the density of silica particles. 50 Refining the particle size from 42 μm to 12 μm increased the chelation reaction rate by 9.6 times. The synergistic effect coefficient of each component reached 1.45.

[0025] 4. Outstanding economic benefits: The gentle ultrasonic technology saves 70% on energy consumption, 15.6% on reagent costs, and avoids an investment of 2.8 million yuan in deep treatment facilities.

[0026] 5. Wide applicability: Applicable to 5 different coal types, it operates stably under conditions of 120-180℃ and pH 8-12. In a long-term test of 30 days, the average scale inhibition rate was 86.3%, and the coefficient of variation was only 2.1%. Attached Figure Description

[0027] Figure 1 This is the trend of silica concentration variation in different dispersants of the present invention;

[0028] Figure 2 This is a comparison of the chelation constants of the present invention;

[0029] Figure 3 This is the pH titration curve of the present invention;

[0030] Figure 4 This is a comparison of COD values ​​of different chelating agent systems of the present invention;

[0031] Figure 5 This is a comparison of the net COD contribution of different formulations in this invention. Detailed Implementation

[0032] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples.

[0033] Example 1

[0034] This embodiment presents a method for preparing an ash water dispersant, comprising the following steps:

[0035] Step 1: Preparation of inorganic-organic hybrid chelating agents:

[0036] Aluminosilicate was activated by alkali treatment with sodium hydroxide solution at 90°C for 3 hours, washed until neutral and dried to obtain activated aluminosilicate; the activated aluminosilicate was dispersed in anhydrous ethanol, a silane coupling agent was added and refluxed at 70°C for 5 hours under nitrogen protection, and the mixture was separated and purified to obtain a hybrid chelating agent.

[0037] The aluminosilicate is selected from 13X molecular sieve zeolite or kaolin, and the silane coupling agent is selected from aminopropyltriethoxysilane, with an amount of 10% of the mass of the aluminosilicate.

[0038] Step 2: Preparation of the composite dispersant composition:

[0039] Prepare a composite dispersant composition by mixing 55 parts by weight of a chelating component, 10 parts by a polymerization inhibitor, 30 parts by a dispersion stabilizing component, and 10 parts by an auxiliary functional component. The chelating component contains a polyhydroxy sugar derivative and a hybrid chelating agent prepared in step 1. The polymerization inhibitor contains a fluoride.

[0040] The chelating component comprises: 22 parts of a nitrogen-containing heterocyclic chelating agent, 30 parts of a polyhydroxy glycosyl derivative, and 10 parts of a hybrid chelating agent; the polyhydroxy glycosyl derivative is selected from sodium gluconate and D-sorbitol.

[0041] The dispersion stabilizing components include: 20 parts of maleic acid-acrylic acid-sulfonic acid terpolymer and 10 parts of polycarboxylic acid dispersant;

[0042] The polymerization inhibitor component comprises: 5 parts sodium fluorosilicate or sodium fluoride, and 5 parts lattice distortion agent; the lattice distortion agent is selected from 1-hydroxyethylidene-1,1-diphosphonic acid.

[0043] Step 3: Gentle ultrasound pretreatment:

[0044] Add an antioxidant to the ash water, sonicate it for 1.5 minutes with a power density of 0.4 W / mL, and then add the composite dispersant composition prepared in step 2.

[0045] Sodium sulfite was selected as the antioxidant, and the concentration was 15 mg / L; the frequency of the ultrasonic treatment was 30 kHz.

[0046] The concentration of the composite dispersant composition is 90 mg / L, and it is prepared into a 25% aqueous solution by wet dosing.

[0047] The method also includes a fluoride ion capture step: adding lime slurry to the treated ash water, and converting fluoride ions into calcium fluoride precipitate by chemical precipitation, so that the fluoride concentration is reduced to below 5 mg / L;

[0048] The amount of lime slurry added was 1.15 times the stoichiometry of fluoride ions, the pH of the precipitation reaction was controlled at 8.8, and the reaction temperature was 70℃.

[0049] Example 2

[0050] The difference between this embodiment and Embodiment 1 is that:

[0051] Step 1: Activate the aluminosilicate with sodium hydroxide solution at 80°C for 2 hours;

[0052] Add silane coupling agent and reflux at 60°C for 4 hours under nitrogen protection;

[0053] The silane coupling agent used is mercaptopropyltrimethoxysilane, and the amount used is 15% of the mass of aluminosilicate.

[0054] Step 2: Preparation of the composite dispersant composition:

[0055] Prepare 40 parts by weight of chelating component, 5 parts by polymerization inhibitory component, 20 parts by dispersion stabilizing component and 5 parts by auxiliary functional component;

[0056] The chelating component comprises: 15 parts of a nitrogen-containing heterocyclic chelating agent, 20 parts of a polyhydroxy glycosyl derivative, and 5 parts of a hybrid chelating agent; the polyhydroxy glycosyl derivative is selected from D-sorbitol or hydroxyethyl cellulose ether.

[0057] The dispersion stabilizing components include: 15 parts of maleic acid-acrylic acid-sulfonic acid terpolymer and 5 parts of polycarboxylic acid dispersant;

[0058] The polymerization inhibitor component comprises: 3 parts sodium fluorosilicate or sodium fluoride, and 2 parts lattice distortion agent; the lattice distortion agent is sodium polyaspartate.

[0059] Step 3: Sonicate for 1 minute with a power density of 0.3 W / mL, and then add the composite dispersant composition prepared in step 2;

[0060] The antioxidant used was ascorbic acid, and the concentration was 10 mg / L; the frequency of the ultrasonic treatment was 20 kHz.

[0061] The concentration of the composite dispersant composition is 60 mg / L, and it is prepared into a 20% aqueous solution by wet dosing.

[0062] The amount of lime slurry added was 1.1 times the stoichiometry of fluoride ions, the pH of the precipitation reaction was controlled at 8.5, and the reaction temperature was 60℃.

[0063] Example 3

[0064] The difference between this embodiment and Embodiment 1 is that:

[0065] Step 1: Activate the aluminosilicate with sodium hydroxide solution at 100°C for 4 hours;

[0066] Add silane coupling agent and reflux at 80°C for 6 hours under nitrogen protection;

[0067] The amount of silane coupling agent used is 15% of the mass of aluminosilicate.

[0068] Step 2: Preparation of the composite dispersant composition:

[0069] Prepare 70 parts by weight of chelating component, 15 parts by polymerization inhibitory component, 40 parts by dispersion stabilizing component and 15 parts by auxiliary functional component;

[0070] The chelating components include: 30 parts of nitrogen-containing heterocyclic chelating agent, 40 parts of polyhydroxy glycosyl derivative, and 15 parts of hybrid chelating agent;

[0071] The dispersion stabilizing components include: 25 parts of maleic acid-acrylic acid-sulfonic acid terpolymer and 15 parts of polycarboxylic acid dispersant;

[0072] The polymerization inhibitory component contains: 8 parts sodium fluorosilicate or sodium fluoride, and 7 parts lattice distortion agent.

[0073] Step 3: Ultrasonic treatment with a power density of 0.5 W / mL for 2 minutes, followed by addition of the composite dispersant composition prepared in step 2;

[0074] The antioxidant concentration was 20 mg / L; the ultrasonic treatment frequency was 40 kHz.

[0075] The concentration of the composite dispersant composition is 120 mg / L, and it is prepared into a 30% aqueous solution by wet dosing.

[0076] The amount of lime slurry added was 1.2 times the stoichiometry of fluoride ions, the pH of the precipitation reaction was controlled at 9.5, and the reaction temperature was 80℃.

[0077] Example 4

[0078] This embodiment presents an ash water dispersant prepared by the method of Example 1, comprising a polyhydroxy sugar derivative, an inorganic-organic hybrid chelating agent, a fluoride polymerization inhibitor, a dispersing stabilizer, and an auxiliary functional agent, achieving a scale inhibition rate of over 85% for polysilicic acid.

[0079] Example 5

[0080] This embodiment presents an ash water dispersant and its preparation method, comprising five main steps: preparation of a hybrid chelating agent, preparation of a dispersant composition, ultrasonic pretreatment, application of the dispersant, and control of byproducts.

[0081] Step 1: Preparation of Inorganic-Organic Hybrid Chelating Agent

[0082] 1.1 Alkali activation treatment:

[0083] Take 100 parts of aluminosilicate, wherein the aluminosilicate is selected from 13X molecular sieve zeolite (SiO2 / Al2O3 molar ratio 20-50, specific surface area ≥500m² / g) or kaolin (Al2O3 content 35-40%, SiO2 content 45-55%, particle size 1-10μm), add a 10-20% (preferably 15%) sodium hydroxide solution (analytical grade, ≥96%), the volume of solution being 3-5 times the mass of aluminosilicate, and treat with mechanical stirring (200-500rpm) at 80-100℃ (preferably 90℃) for 2-4 hours (preferably 3 hours). During this process, sodium hydroxide undergoes a hydrolysis reaction with the silicon-oxygen bonds and aluminum-oxygen bonds on the surface of aluminosilicate, generating surface silanol groups (≡Si-OH) and aluminumol groups (≡Al-OH), and the surface hydroxyl density increases from 2-3 per nm² before treatment to 8-12 per nm². After the reaction, the solution was washed with deionized water until neutral (the pH of the washing solution was 6.5-7.5 as measured by pH test paper), and then dried in a 120℃ forced-air drying oven for 4-6 hours until constant weight was obtained to obtain activated aluminosilicate.

[0084] 1.2 Surface modification of silane coupling agent: The activated aluminosilicate was washed multiple times with deionized water to ensure pH neutrality (6.5-7.5) and no residual alkali. After drying at 110℃ for 2 hours to remove moisture, it was dispersed in anhydrous ethanol (≥99.7%) at a solid-liquid ratio of 1:10-15. The suspension was ultrasonically dispersed for 30 minutes (frequency 40kHz, power 200W) in a three-necked round-bottom flask equipped with a reflux condenser to form a uniform suspension.

[0085] Safety Precautions: Ensure the carrier is completely neutral to prevent residual NaOH from reacting with ethanol under heating conditions to produce sodium ethoxide. Perform the operation in a fume hood with appropriate personal protective equipment.

[0086] Add a silane coupling agent: aminopropyltriethoxysilane (APTES, purity ≥98%, CAS No.: 919-30-2) or mercaptopropyltrimethoxysilane (MPTMS, purity ≥95%, CAS No.: 31001-77-1), the amount of which is 5-15% (preferably 10%) of the mass of aluminosilicate. Reflux the reaction under dry nitrogen protection (flow rate 50-100 mL / min) at 60-80℃ (preferably 70℃) for 4-6 hours (preferably 5 hours), with a stirring speed of 150-200 rpm. During the reaction, the ethoxy group of the silane coupling agent undergoes a condensation reaction with the hydroxyl groups on the surface of the inorganic support (≡Si-OH + (C2H5O)3Si-R → ≡Si-O-Si(OC2H5)2-R +C2H5OH), forming covalently linked silicon-oxygen bonds. Simultaneously, chelating functional groups such as amino (-NH2) or thiol (-SH) groups are introduced onto the support surface. The grafting rate is calculated by determining the C and N content using an elemental analyzer; the target grafting rate is 1.5-3.0 mmol / g support.

[0087] 1.3 Separation, Purification, and Solvent Recovery: After the reaction, the solid product was separated using a high-speed centrifuge (8000 rpm, 10 minutes). The resulting ethanol solution was collected in a dedicated container. The solid product was washed three times with anhydrous ethanol (50 mL / g product each time) to remove unreacted coupling agent. The washing solution was analyzed using Fourier transform infrared spectroscopy. The CH stretching vibration peak (2800-3000 cm⁻¹) was detected. -1 When the intensity no longer decreases significantly, the washing is considered complete.

[0088] Ethanol recovery process: The collected ethanol solution (including reaction mother liquor and washing liquid) is recovered using a distillation unit. The distillation column is a packed column (packing: stainless steel Raschig rings), with a reflux ratio of 2-3:1 and the top temperature controlled at 78-80℃. The collected fraction with an ethanol content ≥95% can be reused, and the ethanol recovery rate is ≥90%. The distillation residue contains a small amount of coupling agent and is disposed of by a qualified unit in accordance with hazardous waste treatment standards.

[0089] The solid product is dried in a forced-air drying oven at 100-120℃ (preferably 110℃) for 4-6 hours to constant weight to obtain a hybrid material with surface-grafted organic chelating groups.

[0090] Step 2: Preparation of the composite dispersant composition

[0091] Prepare the dispersant composition according to the following parts by weight:

[0092] 2.1 Chelation group allocation (40-70 parts, preferably 55 parts):

[0093] 15-30 parts (preferably 20 parts) of nitrogen-containing heterocyclic chelating agent: 2-hydroxyphosphonoacetic acid (HPAA, molecular weight 170, purity ≥95%) or imidazole-4,5-dicarboxylic acid (IDC, molecular weight 156, purity ≥98%).

[0094] 20-40 parts (preferably 30 parts) of polyhydroxy glycoside derivatives: sodium gluconate (molecular weight 218, purity ≥99%), D-sorbitol (molecular weight 182, purity ≥98%) or hydroxyethyl cellulose ether (MS=1.8-2.5, viscosity 2000-5000 mPa·s).

[0095] 5-15 parts (preferably 10 parts) of the hybrid chelating agent prepared in step one.

[0096] 2.2 Polymerization inhibition group allocation (5-15 parts, preferably 10 parts):

[0097] 3-8 parts (preferably 5 parts) of sodium fluorosilicate (Na2SiF6, purity ≥98%) or sodium fluoride (NaF, purity ≥99%).

[0098] Lattice distortion agent 2-7 parts (preferably 5 parts): 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP, molecular weight 206, effective content ≥60%) or sodium polyaspartate (PASP, molecular weight 5000-15000).

[0099] 2.3 Dispersed stable group allocation (20-40 portions, preferably 30 portions):

[0100] 15-25 parts of maleic acid-acrylic acid-sulfonic acid terpolymer (molecular weight 30,000-50,000, sulfonic acid group content 15-25%);

[0101] 5-15 parts of polycarboxylic acid dispersant (polyacrylic acid, molecular weight 2000-8000).

[0102] 2.4 Auxiliary function group allocation system (5-15 parts, preferably 10 parts):

[0103] Corrosion inhibitor: 2-5 parts of benzotriazole (BTA, purity ≥99%);

[0104] Biological inhibitor: 1-3 parts of dodecyl dimethyl benzyl ammonium chloride (DDBAC, effective content ≥80%, CAS No.: 139-07-1);

[0105] Compatibility Note: When using quaternary ammonium salt bactericides and fluorides simultaneously, avoid mixing under strongly acidic conditions to prevent the generation of hydrogen fluoride gas. It is recommended to use under pH ≥ 7 conditions, store each component separately, and mix them on-site before use. - Defoamer: 1-2 parts of silicone defoamer (effective content ≥ 99%).

[0106] 2.5 Mixing process: Mix the above components in a high-speed mixer for 30-60 minutes (1000-1500 rpm) according to the proportion. The uniformity of mixing is judged by visual inspection to ensure that there is no layering or clumping. The resulting composite dispersant composition is a uniform powder that is light yellow to yellowish-brown in appearance.

[0107] Step 3: Mild-condition ultrasonic pretreatment

[0108] 3.1 Pre-addition of antioxidants:

[0109] Before the ash water is fed into the ultrasonic treatment unit, an antioxidant is added via a precision metering pump (accuracy ±2%). Sodium sulfite or ascorbic acid is selected, with a concentration of 10-20 mg / L (preferably 15 mg / L). The addition method involves setting up an inlet on the ash water pipeline, and the addition rate is automatically adjusted according to the ash water flow rate (mass flow ratio 1:50000-100000). The antioxidant and ash water are mixed evenly for no less than 30 seconds, and uniform dispersion is ensured by an online static mixer (mixing efficiency ≥95%).

[0110] Operational safety tips: Sodium sulfite reacts with acid to produce sulfur dioxide gas. It should be operated in a well-ventilated environment. An SO2 gas detector should be used. Forced ventilation should be activated when the concentration exceeds 2 mg / m³.

[0111] 3.2 Gentle ultrasonic treatment:

[0112] A multi-frequency ultrasonic generator (adjustable frequency 20-40kHz, preferably 28kHz) was used, with a power density controlled at 0.3-0.5W / mL (preferably 0.4W / mL). The ultrasonic transducer was made of titanium alloy (50-100mm in diameter), and the treatment time was 1-2 minutes (preferably 1.5 minutes). Ultrasonic treatment was carried out in a dedicated stainless steel reactor with a volume designed to be 1 / 10-1 / 5 of the ash water flow rate. Multiple ultrasonic transducers were installed on the inner wall to ensure uniform ultrasonic field distribution. During the treatment, the ash water temperature was controlled at 80-120℃, and circulating cooling was used to prevent overheating. The ultrasonic cavitation effect refined the silica scale microcrystal size from 10-50μm to 10-15μm. The particle size distribution was measured using a laser particle size analyzer (Mastersizer 3000). 50 The value is controlled within 12±3μm.

[0113] 3.3 Dispersant addition and mixing:

[0114] Immediately after ultrasonic treatment, the ash water enters the dispersant dosing unit, where the composite dispersant composition prepared in step two is added at a concentration of 60-120 mg / L (preferably 90 mg / L). The addition method is wet dosing (prepared as a 20%-30% aqueous solution). The dosing point is located before the pipe mixer after the ultrasonic reactor outlet. A static mixer (Kenics type, with no fewer than 6 mixing elements and a pressure drop <50 kPa) ensures thorough mixing of the dispersant and ash water for at least 120 seconds.

[0115] Reaction monitoring: The fluoride ion concentration in the ash water after mixing is 5-15 mg / L, which is monitored in real time using an ion-selective electrode method (detection limit 0.1 mg / L). Fluoride ions react with silicic acid to form fluorosilicone complex ions (SiF6). 2- The silicic acid content before and after the reaction was determined using the silicic molybdenum blue spectrophotometric method (wavelength 815 nm). The conversion rate should reach 60%-80%. If the conversion rate is insufficient, the contact time can be appropriately extended or the pH can be adjusted to 9.0-9.5.

[0116] Step 4: Fluoride ion capture and byproduct control

[0117] 4.1 Fluoride ion recovery and precipitation treatment:

[0118] (1) Preparation of lime milk: Quicklime (CaO, purity ≥85%) is added to clean water at a weight ratio of 1:3 to prepare calcium hydroxide suspension. The concentration is controlled at 100-200mg / L (preferably 150mg / L). The suspension is maintained by stirring (speed 100-200rpm).

[0119] (2) Precipitation reaction: Add lime slurry to a dedicated sedimentation tank at a dosage of 1.1-1.2 times the stoichiometry of fluoride ions. Maintain a sedimentation time of 30-45 minutes and control the pH at 8.5-9.5 (monitored online with a pH meter). Keep the reaction temperature at 60-80℃ and the stirring intensity at 50-100 rpm to ensure thorough mixing.

[0120] (3) Solid-liquid separation and waste treatment: Gravity sedimentation is carried out in an inclined plate sedimentation tank, with the upward flow velocity controlled at 0.5-1.0 mm / s and the sedimentation time not less than 2 hours. The fluoride concentration of the supernatant is determined by ion-selective electrode method, and is required to be ≤5 mg / L. After meeting the standard, it can be returned to the system or sent to the wastewater treatment unit.

[0121] The bottom sludge is dewatered by a plate and frame filter press (pressure 0.6-0.8MPa, filtration time 2-3 hours, filter cake moisture content ≤60%).

[0122] Resource utilization of calcium fluoride slag:

[0123] Quality requirements: Fluorine content 15%-25%, heavy metal content conforming to GB 5085.3 standard;

[0124] Applications: It can be used as a flux in cement production (dosage ≤ 5%), or as a raw material in the ceramic industry (it needs to be verified by toxicity leaching test, in accordance with HJ 557-2010 standard).

[0125] Quality control: Each batch must undergo fluorine content analysis (ion-selective electrode method) and heavy metal detection (atomic absorption spectrometry), and a quality inspection report must be issued;

[0126] Storage requirements: Store in a sealed warehouse, categorized by type, with waterproof pallets to prevent rainwater from washing away the contents.

[0127] Alternative safe disposal plan: If calcium fluoride slag cannot be utilized as a resource, it should be treated as hazardous waste and entrusted to a qualified unit for harmless disposal (waste category: HW32).

[0128] 4.2 Bioaugmentation Treatment System:

[0129] (1) Strain isolation and identification: Sludge samples were taken from the stable coal chemical wastewater biochemical pond and isolated by plate dilution method using LB medium. Strains with strong sugar degradation ability were selected and preliminarily identified by API 20NE biochemical identification kit. Then, molecular identification was performed by 16S rRNA gene amplification sequencing (primer 27F / 1492R). The target strains were Pseudomonas sp. and Bacillus sp.

[0130] (2) Strain tolerance acclimatization: Prepare simulated wastewater culture medium (sodium gluconate 500 mg / L, sorbitol 300 mg / L, NaCl concentration gradient increased to 8000 mg / L, NaF concentration gradient increased to 20 mg / L), and acclimatize and culture for 7-10 generations at 30℃ and 180 rpm, with each generation cultured for 24 hours. The acclimatization effect is evaluated by measuring the bacterial density and COD removal rate.

[0131] (3) Preparation of compound bacterial agent: 3-5 selected dominant bacterial strains were cultured to the logarithmic growth phase, mixed at a volume ratio of 1:1:1, and centrifuged to collect the bacterial cells (4000 rpm, 10 minutes). The cells were resuspended in 10% glycerol solution to prepare the bacterial agent. The viable cell count was determined by plate counting, requiring ≥10. 9 CFU / g, store at 4℃ for later use.

[0132] (4) On-site application and biosafety: Add compound bacterial agent at the inlet of the biochemical tank, with an addition amount of 50-100g / m³ wastewater (preferably 75g / m³), and add it 1-2 times per week.

[0133] Biosafety measures:

[0134] Microbial agent transportation and storage: Use biosafety packaging, transport at 4℃ cold chain to avoid temperature fluctuations;

[0135] Operational protection: Operators should wear protective gloves and masks to avoid direct contact with the disinfectant;

[0136] Environmental release control: All strains are environmentally friendly, do not contain pathogens, and comply with the "General Technical Guidelines for Biosafety of Microbial Fertilizers" (NY 1109-2017); - Emergency handling: In case of accidental leakage, disinfect with 75% alcohol to prevent the spread of strains.

[0137] Verification Experiment

[0138] Experiment 1: Comparison of Scale Inhibition Rate of Silica Scale

[0139] 1. Experimental Objective

[0140] The scale inhibition effect of the composite dispersant of the present invention compared with the existing sulfonic acid copolymer dispersant in high silica content grey water was verified, demonstrating the technical effect of increasing the scale inhibition rate from 40% to over 87%.

[0141] 2. Preparation of experimental samples

[0142] (1) Existing technology comparison sample: sulfonic acid-acrylic acid copolymer dispersant, molecular weight 30,000-50,000, sulfonic acid group content 15%-25%, effective content ≥98%;

[0143] (2) Test sample of the present invention: The composite dispersant composition prepared according to Example 4, calculated by mass parts: chelating component 52.4% (containing 28.6% polyhydroxy sugar derivative, 9.5% hybrid chelating agent, and 19.0% nitrogen-containing heterocyclic chelating agent), polymerization inhibitor component 9.5%, dispersion stabilizing component 28.6%, and auxiliary functional component 9.5%;

[0144] (3) Simulated grey water: SiO2 500±10mg / L, Ca 2+ 200±5mg / L, Mg 2+ 50±3 mg / L, pH 10.0±0.1, total hardness 1200±50 mg / L.

[0145] 3. Experimental conditions

[0146] Experimental temperature: 120±2℃; Experimental time: 24 hours; Stirring speed: 200rpm; pH value: 10.0±0.1; Dispersant concentration: 90mg / L in the prior art and 90mg / L in this invention (equal volume comparison).

[0147] 4. Experimental Procedure

[0148] (1) Add 800 mL of simulated ash water to a 1000 mL high-temperature and high-pressure reactor and heat it to 120 °C;

[0149] (2) A blank control group (without dispersant), a prior art group (with 90 mg / L of sulfonic acid copolymer dispersant), and an invention group (with 90 mg / L of composite dispersant) were set up respectively.

[0150] (3) Stir continuously for 24 hours under constant temperature conditions, and take a sample every 4 hours to determine the concentration of silicic acid;

[0151] (4) After the experiment, the solution was filtered through a 0.45 μm membrane, and the concentration of the remaining silicic acid in the filtrate was measured.

[0152] (5) Calculate the silica scale deposition rate: Silica scale deposition rate (%) = (C0-C1) / C0×100%, where C0 is the initial silica concentration and C1 is the remaining silica concentration; Scale inhibition rate (%) = (Deposition rate of blank control - deposition rate of experimental group) / Deposition rate of blank control ×100%;

[0153] (6) Each experiment was repeated 6 times and the average value was taken.

[0154] 5. Experimental Results

[0155]

[0156] Note: Silica scale deposition rate = (Initial concentration - Residual concentration) / Initial concentration × 100%; Scale inhibition rate = (Blank deposition rate - Test group deposition rate) / Blank deposition rate × 100%

[0157] Figure 1 The trend of silica concentration variation is shown for different dispersants.

[0158] 6. Analysis and Summary

[0159] Experimental results show that the composite dispersant of this invention achieves a scale inhibition rate of 78.9% in high-silica grey water, a 143.5% improvement compared to the 32.4% of existing sulfonic acid copolymer dispersants. At the same dosage concentration (90 mg / L), this invention maintains a residual silicic acid concentration of 436.8 mg / L (silicone scale deposition rate of only 12.6%), while the existing technology has a residual silicic acid concentration of 298.2 mg / L (silicone scale deposition rate of 40.4%), and the blank control has a residual silicic acid concentration of only 201.5 mg / L (silicone scale deposition rate of 59.7%). This confirms that the multi-point chelation mechanism of polyhydroxy glycosyl derivatives and the polymerization inhibition effect of fluoride ions can significantly improve the control of high-polymer silicic acid and effectively prevent silicic acid polymerization and precipitation.

[0160] Experiment 2: Determination of Chelation Constant

[0161] 1. Experimental Objective

[0162] The chelation constant of glycosyl derivatives for silicic acid was accurately determined by pH-stat potentiometric titration, verifying the technological innovation that improves the chelation constant by 1.6 orders of magnitude (from lgK=4.2 to lgK=6.8) compared to traditional chelating agents.

[0163] 2. Preparation of experimental samples

[0164] (1) Traditional chelating agent: 2-hydroxyphosphonoacetic acid (HPAA), molecular weight 170, purity ≥95%;

[0165] (2) Glycosyl derivative: Sodium gluconate, molecular weight 218, purity ≥99%;

[0166] (3) Silicic acid standard solution: Prepare a 1.0 mmol / L standard solution with sodium silicate and adjust it to the state of monomeric silicic acid with dilute hydrochloric acid;

[0167] (4) Titrant: 0.1000 mol / L NaOH standard solution, the accurate concentration of which is determined by standardization.

[0168] 3. Experimental conditions

[0169] Experimental temperature: 25.0±0.1℃; Ionic strength: 0.1000mol / L (adjusted with NaCl); pH range: 3.0-11.0; Nitrogen protection: high-purity nitrogen was introduced throughout the experiment to remove CO2; Titration rate: 0.02mL / min.

[0170] 4. Experimental Procedure

[0171] (1) Prepare 100 mL of a solution containing 1.0 mmol / L silicic acid and adjust the ionic strength to 0.1 mol / L;

[0172] (2) Add the traditional chelating agent (HPAA) and the glycosyl derivative (sodium gluconate) respectively, in a molar ratio of 1:1;

[0173] (3) Adjust the initial pH to 3.0 with 0.1 mol / L HCl and begin titration under nitrogen protection;

[0174] (4) Add 0.1 mol / L NaOH solution dropwise at a rate of 0.02 mL / min using an automatic potentiometric titrator;

[0175] (5) Record the pH-titer volume curve, recording one data point for every 0.1 pH unit;

[0176] (6) Process the data using the Gran function method and calculate the chelation constant lgK value;

[0177] (7) Each sample was measured 5 times, and the average value and standard deviation were calculated.

[0178] 5. Experimental Results

[0179]

[0180] Figure 2 The comparison of chelation constants is shown;

[0181] Figure 3 The pH titration curve is shown.

[0182] 6. Analysis and Summary

[0183] Experimental results confirmed that the chelation constant lgK of sodium gluconate was 6.82±0.12, which is 2.64 lg units higher than that of the traditional HPAA chelating agent (4.18±0.08), or 43.7 times, exceeding the target improvement of 1.6 orders of magnitude. This is attributed to the presence of ortho- and posterior polyhydroxy structures (C2, C3, and C4 positions), enabling sodium gluconate to form multidentate chelate complexes with silicic acid, while traditional HPAA can only provide single-point chelation. pH titration curves showed that sodium gluconate has better buffering capacity and a wider effective pH range, demonstrating the superiority of the multi-point chelation mechanism.

[0184] Experiment 3: Comparison of COD Contributions

[0185] 1. Experimental Objective

[0186] The study measured and compared the COD contribution of traditional organic chelating agent formulations and formulations that partially replaced them with hybrid chelating agents, verifying that the hybrid chelating agent substitution technology can achieve an environmentally friendly effect of reducing COD by more than 46%.

[0187] 2. Preparation of experimental samples

[0188] (1) Traditional organic chelating agent formulation: sodium gluconate 50mg / L + HPAA 30mg / L, simulating the traditional all-organic chelating agent formulation, with a total dosage of 80mg / L;

[0189] (2) Hybrid chelating agent alternative formulation: sodium gluconate 25mg / L + inorganic-organic hybrid chelating agent 40mg / L + HPAA 15mg / L, according to the preferred ratio in Example 4, with a total dosage of 80mg / L;

[0190] (3) Pure hybrid chelating agent control: Inorganic-organic hybrid chelating agent 80 mg / L;

[0191] (4) Blank control: Deionized water;

[0192] (5) Test water: meets the first-class water standard of GB / T 6682-2008.

[0193] 3. Experimental conditions

[0194] Experimental temperature: 20±1℃; pH value: 7.0±0.2; reaction time: 2 hours; stirring speed: 150 rpm; determination method: potassium dichromate method (GB 11914-89).

[0195] 4. Experimental Procedure

[0196] (1) Prepare 8 500mL conical flasks and label them as blank control A and B, traditional formula C and D, hybrid alternative formula E and F, and pure hybrid chelating agent G and H respectively;

[0197] (2) Add 400 mL of test water to each conical flask and add the corresponding chelating agent according to the formula;

[0198] (3) Stir at 150 rpm for 2 hours on a constant temperature shaker to ensure that the chelating agent is completely dissolved;

[0199] (4) Take a 100 mL sample and determine the COD value according to the potassium dichromate method of GB 11914-89;

[0200] (5) Heat under reflux for 2 hours, cool, and then titrate the remaining potassium dichromate with ferrous ammonium sulfate;

[0201] (6) Calculate COD value: COD (mg / L) = (Vblank - Vsample) × c × 8000 / Vsample;

[0202] (7) Each group of samples was measured 3 times, and the average value and relative standard deviation were calculated.

[0203] 5. Experimental Results

[0204]

[0205] Figure 4 The COD values ​​of different chelating agent systems are compared.

[0206] Figure 5 The comparison of the net COD contribution of different formulations is shown.

[0207] 6. Analysis and Summary

[0208] Experimental results validate the environmentally friendly advantages of hybrid chelating agent technology:

[0209] (1) The COD contribution of the traditional organic formulation is 51.8 mg / L;

[0210] (2) The COD contribution of the hybrid alternative formulation was reduced to 27.6 mg / L, with a reduction rate of 46.7%, achieving the expected target;

[0211] (3) The COD contribution of the pure hybrid chelating agent is only 2.4 mg / L, with a reduction rate of 95.4%, which proves the ultra-low COD characteristics of the hybrid chelating agent itself.

[0212] The results show that the inorganic carrier does not generate COD, with only the surface organic functional groups contributing trace amounts of COD; the highly efficient chelating ability of the hybrid chelating agent can reduce the dosage of traditional organic chelating agents by more than 50%; and the chemical stability of the inorganic framework prevents the degradation of organic matter from generating additional COD. This technology provides an effective solution for achieving environmentally friendly water treatment agents.

[0213] The embodiments of the present invention have been described above. However, the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more equivalent embodiments under the guidance of the present embodiments, and all of them are within the protection scope of the present embodiments.

Claims

1. A method for preparing an ash-water dispersant, characterized in that, Includes the following steps: Step 1: Preparation of inorganic-organic hybrid chelating agents: Aluminosilicate is activated by alkali treatment with sodium hydroxide solution at 80-100℃ for 2-4 hours, washed until neutral and dried to obtain activated aluminosilicate; the activated aluminosilicate is dispersed in anhydrous ethanol, a silane coupling agent is added and refluxed at 60-80℃ for 4-6 hours under nitrogen protection, and the mixture is separated and purified to obtain a hybrid chelating agent. Step 2: Preparation of the composite dispersant composition: Prepare a composite dispersant composition by mixing 40-70 parts by weight of a chelating component, 5-15 parts by weight of a polymerization inhibitor, 20-40 parts by weight of a dispersion stabilizing component, and 5-15 parts by weight of an auxiliary functional component. The chelating component contains a polyhydroxy sugar derivative and a hybrid chelating agent prepared in step 1. The polymerization inhibitor contains a fluoride. The chelating component comprises: 15-30 parts of a nitrogen-containing heterocyclic chelating agent, 20-40 parts of a polyhydroxy glycosyl derivative, and 5-15 parts of a hybrid chelating agent; the polyhydroxy glycosyl derivative is selected from sodium gluconate or D-sorbitol. The polymerization inhibitory component comprises: 3-8 parts of sodium fluorosilicate or sodium fluoride, and 2-7 parts of lattice distortion agent; the lattice distortion agent is selected from 1-hydroxyethylidene-1,1-diphosphonic acid or sodium polyaspartate. The dispersion stabilizing component comprises: 15-25 parts of maleic acid-acrylic acid-sulfonic acid terpolymer and 5-15 parts of polycarboxylic acid dispersant; Step 3: Gentle ultrasound pretreatment: Add an antioxidant to the ash water, treat it with ultrasound at a power density of 0.3-0.5 W / mL for 1-2 minutes, and then add the composite dispersant composition prepared in step 2. The antioxidant is selected as sodium sulfite or ascorbic acid, and the concentration is 10-20 mg / L; the frequency of the ultrasonic treatment is 20-40 kHz. The concentration of the composite dispersant composition is 60-120 mg / L, and it is prepared into an aqueous solution with a mass fraction of 20%-30% by wet dosing.

2. The method according to claim 1, characterized in that, The aluminosilicate is selected from 13X molecular sieve zeolite or kaolin, and the silane coupling agent is selected from aminopropyltriethoxysilane or mercaptopropyltrimethoxysilane, with an amount of 5-15% of the mass of the aluminosilicate.

3. The method according to claim 1, characterized in that, It also includes a fluoride ion capture step: adding lime slurry to the treated ash water, and converting fluoride ions into calcium fluoride precipitate through chemical precipitation, so that the fluoride concentration is reduced to below 5 mg / L.

4. The method according to claim 3, characterized in that, The amount of lime slurry added is 1.1-1.2 times the stoichiometry of fluoride ions, the pH of the precipitation reaction is controlled at 8.5-9.5, and the reaction temperature is 60-80℃.

5. A water-based dispersant prepared by the method according to any one of claims 1-4, characterized in that, It contains polyhydroxy sugar derivatives, inorganic-organic hybrid chelating agents, polymerization inhibitors containing fluorides, dispersion stabilizers, and auxiliary functional components.

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