Anti-precipitation coal water slurry additive and preparation method thereof

Abstract

The invention relates to the technical field of coal water slurry additives, and discloses an anti-precipitation coal water slurry additive and a preparation method thereof, the anti-precipitation coal water slurry additive comprises the following raw materials by weight: 10-20 parts of modified nano silica, 30-40 parts of a bio-based dispersant prepared from corn straw, 5-10 parts of an ionic liquid stabilizer, and 3-5 parts of a compound synergist; the method comprises the following steps: S1, pretreating corn straws and preparing modified nano silicon dioxide; and S2, weighing the components according to the proportion, dispersing, and grinding and granulating after the dispersion is completed. The modified nano S < iO2 > is adsorbed on the surfaces of coal particles as a'rigid core ', and sedimentation is inhibited through steric hindrance; the ionic liquid forms a flexible shell, the interfacial tension is reduced, and the low-temperature fluidity is improved. The corn straw is used for replacing a traditional petroleum-based dispersing agent, and the cost is reduced by 40% or above. The compounded synergist automatically adjusts the pH value of the slurry to 8-9 according to the environment, and prolongs the stable period to 30 days.

Description

Technical Field

[0001] The present invention relates to the technical field of coal water slurry additives, and in particular to a coal water slurry additive for preventing precipitation and a preparation method thereof. Background Art

[0002] Coal-water slurry is a high-concentration suspended fuel composed of coal powder, water and additives. It is widely used in power generation, metallurgy and other fields due to its clean and efficient characteristics. However, coal-water slurry is prone to particle sedimentation and stratification during storage and transportation, resulting in decreased fluidity, pipeline blockage and reduced combustion efficiency, which seriously restricts its large-scale application. At present, the industry mainly improves stability by adding dispersants, but traditional dispersants (such as lignin sulfonates and naphthalene sulfonates) mainly maintain slurry stability in the short term through electrostatic repulsion, but it is difficult to resist particle aggregation caused by long-term standing or temperature fluctuations. In addition, most dispersants rely on petrochemical raw materials (such as benzene ring structure monomers), and their prices are affected by fluctuations in the crude oil market. In addition, the synthesis process produces sulfur-containing and nitrogen-containing wastewater. Summary of the Invention

[0003] In view of this, the present invention proposes a water-coal slurry additive for preventing precipitation and a preparation method thereof, aiming to solve the problems in current technology that it is difficult to resist particle aggregation caused by long-term standing or temperature fluctuations and that most dispersants rely on petrochemical raw materials.

[0004] On the one hand, the present invention proposes a water-coal slurry additive for preventing precipitation, comprising the following raw materials in parts by weight: 10-20 parts of modified nano-silica, 30-40 parts of a bio-based dispersant prepared from corn straw, 5-10 parts of an ionic liquid stabilizer, and 3-5 parts of a compound synergist.

[0005] Optionally, the modified nano-silica has a particle size of 20-50 nm and a specific surface area of 200-400 m 2 / g; the ionic liquid stabilizer is 1-butyl-3-methylimidazole dihydrogen phosphate.

[0006] Optionally, the compound synergist includes sodium polyaspartate and trisodium citrate, and the ratio of the sodium polyaspartate to the trisodium citrate is 2:1.

[0007] On the other hand, the present application also provides a method for preparing a water-coal slurry additive for preventing precipitation, comprising:

[0008] S1: corn straw pretreatment and preparation of modified nano-silica;

[0009] S2: Weigh each component in proportion and disperse them. After dispersion, grind and granulate them.

[0010] Optionally, the preparation of the modified nano-silica includes:

[0011] Add 10 kg of nano-SiO2 into 100 L of ethanol and stir at 800 rpm to form a uniform suspension;

[0012] 1.5 kg APTES was added dropwise, nitrogen was introduced to remove oxygen, and the temperature was raised to 60°C;

[0013] After 4 h of reaction, the solid was separated using a tubular centrifuge at 8000 rpm and washed with ethanol until the filtrate conductivity was <10 μS / cm;

[0014] The solid material was transferred to a vacuum drying oven and dried until the moisture content was less than 1% to obtain white powdery modified SiO2.

[0015] Optionally, the corn straw pretreatment includes:

[0016] 10 kg of corn stalks were crushed and mixed with 50 kg of 5 wt% H2SO3 solution, stirred at 80°C for 1 hour, filtered and washed with water;

[0017] The treated straw was treated with 80 kg of 10 wt% NaOH solution in a reactor at 80° C. for 2 hours, and the cellulose filter cake was obtained by filtration;

[0018] Disperse the cellulose filter cake in 200 L of water, add 12 kg of sodium chloroacetate and 3 kg of 30% H2O2;

[0019] Use NaOH to maintain pH = 11, react at 60 ° C for 3 hours;

[0020] The reaction solution was filtered through a plate-and-frame filter press, and the filtrate was neutralized with hydrochloric acid to pH=7, concentrated to a solid content of 30%, and then spray-dried.

[0021] Optionally, the S2 further includes:

[0022] After weighing each component, add 200L of deionized water and disperse at a speed of 10000rpm.

[0023] Optionally, the grinding needs to be performed until the slurry D50 is ≤ 50 μm.

[0024] Optionally, the finished granules produced by the granulation have a particle size of 80-100 mesh.

[0025] Compared with existing technologies, the technical effects of this application are as follows: modified nano-SiO2 acts as a "rigid core" adsorbed on the surface of coal particles, inhibiting sedimentation through steric hindrance; the ionic liquid forms a "flexible shell," reducing interfacial tension and improving low-temperature fluidity. Replacing traditional petroleum-based dispersants with corn straw reduces costs by over 40%. A compounded synergist automatically adjusts the slurry pH to 8-9 based on the environment, extending the stability period to 30 days. The bio-based dispersant prepared from modified nano-SiO2 and corn straw in this invention works synergistically, significantly reducing the sedimentation rate of the coal-water slurry through steric hindrance and electrostatic repulsion, extending the stability period, and maintaining good fluidity during long-term storage and transportation. The ionic liquid stabilizer, with its low melting point and high thermal stability, effectively reduces interfacial tension, improves the low-temperature fluidity of the coal-water slurry, and prevents particle agglomeration at high temperatures, maintaining stability even at extreme temperatures. The additive effectively reduces the viscosity of high-solids coal slurries and improves their shear recovery, enabling stable transportation even at high solids contents, reducing transportation costs. Replacing traditional petroleum-based dispersants with corn straw reduces raw material costs and reduces pollution from burning agricultural waste. Compared to traditional dispersants, the additive used in this invention is much smaller, further reducing the cost of use. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0027] This embodiment provides a water-coal slurry additive for preventing precipitation, comprising the following raw materials in parts by weight: 10-20 parts of modified nano-silica, 30-40 parts of a bio-based dispersant prepared from corn straw, 5-10 parts of an ionic liquid stabilizer, and 3-5 parts of a compound synergist.

[0028] In some embodiments of the present application, the modified nano-silica has a particle size of 20-50 nm and a specific surface area of 200-400 m 2 / g; the ionic liquid stabilizer is 1-butyl-3-methylimidazole dihydrogen phosphate.

[0029] In some embodiments of the present application, the compound synergist includes sodium polyaspartate and trisodium citrate, and the ratio of the sodium polyaspartate to the trisodium citrate is 2:1.

[0030] It is understandable that the amino groups in the modified nano-silica form hydrogen bonds with oxygen-containing functional groups (such as -COOH) on the surface of coal, enhancing adsorption; the nanoparticles form a "three-dimensional barrier" at the coal / water interface, inhibiting particle sedimentation through steric hindrance. The degree of substitution (DS) of the bio-based dispersant prepared from corn straw is 0.8-1.2, significantly higher than that of industrial-grade CMC (DS=0.6), and the dispersion efficiency is improved by 30%; and the use of agricultural waste reduces costs, saving about 1,200 yuan per ton of additive raw materials; 1-butyl-3-methylimidazole dihydrogen phosphate has a low melting point and can adapt to ambient temperatures of -10-50°C; phosphate ions react with metal ions in coal (such as Ca 2+ 、Fe 3+ ) complexation to reduce "bridging" agglomeration; cationic groups adsorb on the coal surface to form a double electric layer with a Zeta potential of -45mV, enhancing electrostatic stabilization; sodium polyaspartate is used in an amount of 2 / 3, as a biodegradable chelating agent, preferentially binding Fe 3+ Mg 2+ Plasma; trisodium citrate is used at 1 / 3 the dosage to adjust the slurry pH to 8.5-9.0, inhibiting oxidation reactions on the coal surface. Furthermore, the long-chain structure of sodium polyaspartate wraps around the coal particles, forming a pH buffer system with trisodium citrate, preventing the additive from becoming ineffective in an acidic environment.

[0031] In summary, the bio-based dispersant prepared from modified nano-SiO2 and corn straw in this invention works synergistically, significantly reducing the sedimentation rate of coal-water slurries through steric hindrance and electrostatic repulsion, extending the stability period, and maintaining good fluidity during long-term storage and transportation. The ionic liquid stabilizer, with its low melting point and high thermal stability, effectively reduces interfacial tension, improves the low-temperature fluidity of coal-water slurries, and prevents particle agglomeration at high temperatures, maintaining stability even at extreme temperatures. The additive can effectively reduce the viscosity of high-solids coal slurries and improve their shear recovery, enabling stable transport even at high solids contents and reducing transportation costs. Replacing traditional petroleum-based dispersants with corn straw reduces raw material costs and mitigates pollution from agricultural waste incineration. Compared to traditional dispersants, the additive requires a lower dosage, further reducing its cost of use. The modified nano-SiO2 acts as a "rigid core" adsorbed on the surface of coal particles, inhibiting sedimentation through steric hindrance; the ionic liquid forms a "flexible shell," reducing interfacial tension and improving low-temperature fluidity. Replacing traditional petroleum-based dispersants with corn straw reduces costs by over 40%. The compound synergist automatically adjusts the slurry pH to 8-9 according to the environment and extends the stability period to 30 days.

[0032] The present application also provides a method for preparing a water-coal slurry additive for preventing precipitation, the method comprising:

[0033] S1: corn straw pretreatment and preparation of modified nano-silica;

[0034] S2: Weigh each component in proportion and disperse them. After dispersion, grind and granulate them.

[0035] In some embodiments of the present application, the preparation of the modified nano-silica includes:

[0036] Add 10 kg of nano-SiO2 into 100 L of ethanol and stir at 800 rpm to form a uniform suspension;

[0037] 1.5 kg APTES was added dropwise, nitrogen was introduced to remove oxygen, and the temperature was raised to 60°C;

[0038] After 4 h of reaction, the solid was separated using a tubular centrifuge at 8000 rpm and washed with ethanol until the filtrate conductivity was <10 μS / cm;

[0039] The solid material was transferred to a vacuum drying oven and dried until the moisture content was less than 1% to obtain white powdery modified SiO2.

[0040] In some embodiments of the present application, the corn stover pretreatment includes:

[0041] 10 kg of corn stalks were crushed and mixed with 50 kg of 5 wt% H2SO3 solution, stirred at 80°C for 1 hour, filtered and washed with water;

[0042] The treated straw was treated with 80 kg of 10 wt% NaOH solution in a reactor at 80° C. for 2 hours, and the cellulose filter cake was obtained by filtration;

[0043] Disperse the cellulose filter cake in 200 L of water, add 12 kg of sodium chloroacetate and 3 kg of 30% H2O2;

[0044] Use NaOH to maintain pH = 11, react at 60 ° C for 3 hours;

[0045] The reaction solution was filtered through a plate-and-frame filter press, and the filtrate was neutralized with hydrochloric acid to pH=7, concentrated to a solid content of 30%, and then spray-dried.

[0046] In some embodiments of the present application, the S2 further includes:

[0047] After weighing each component, add 200L of deionized water and disperse at a speed of 10000rpm.

[0048] In some embodiments of the present application, the grinding needs to be performed until the slurry D50 is ≤ 50 μm.

[0049] In some embodiments of the present application, the finished granules produced by the granulation have a particle size of 80-100 mesh.

[0050] In summary, the bio-based dispersant prepared from the modified nano-SiO2 and corn straw of the present invention works synergistically, significantly reducing the precipitation rate of the water-coal slurry through steric hindrance and electrostatic repulsion effects, extending the stability period, and maintaining good fluidity during long-term storage and transportation. The ionic liquid stabilizer has a low melting point and high thermal stability, which can effectively reduce interfacial tension, improve the low-temperature fluidity of the water-coal slurry, and prevent particle agglomeration at high temperatures, so that it can remain stable at extreme temperatures. The additive of the present invention can effectively reduce the viscosity of high-solid content coal slurry and improve its shear recovery rate, so that it can maintain stable transportation even at high solid content, reducing transportation costs. Replacing traditional petroleum-based dispersants with corn straw reduces raw material costs and reduces pollution from the incineration of agricultural waste. Compared with traditional dispersants, the additive of the present invention is used in less amount, further reducing the cost of use.

[0051] The technical effects of this application are described below through examples.

[0052] Example 1: Verification of long-term anti-precipitation performance under high temperature environment

[0053] 1.1 Experimental Design

[0054] Additive formula: 18 parts of modified nano-SiO2, 35 parts of bio-based dispersant, 8 parts of ionic liquid stabilizer, and 4 parts of compound synergist.

[0055] Preparation method:

[0056] Add 10 kg of nano-SiO2 into 100 L of ethanol and stir at 800 rpm to form a uniform suspension;

[0057] 1.5 kg APTES was added dropwise, nitrogen was introduced to remove oxygen, and the temperature was raised to 60°C;

[0058] After 4 h of reaction, the solid was separated using a tubular centrifuge at 8000 rpm and washed with ethanol until the filtrate conductivity was <10 μS / cm;

[0059] The solid material was transferred to a vacuum drying oven and dried until the moisture content was less than 1% to obtain white powdery modified SiO2.

[0060] 10 kg of corn stalks were crushed and mixed with 50 kg of 5 wt% H2SO3 solution, stirred at 80°C for 1 hour, filtered and washed with water;

[0061] The treated straw was treated with 80 kg of 10 wt% NaOH solution in a reactor at 80° C. for 2 hours, and the cellulose filter cake was obtained by filtration;

[0062] Disperse the cellulose filter cake in 200 L of water, add 12 kg of sodium chloroacetate and 3 kg of 30% H2O2;

[0063] Use NaOH to maintain pH = 11, react at 60 ° C for 3 hours;

[0064] The reaction solution was filtered through a plate-and-frame filter press, and the filtrate was neutralized with hydrochloric acid to pH=7, concentrated to a solid content of 30%, and then spray-dried.

[0065] Weigh each component in proportion and disperse them. After dispersion, grind and granulate them.

[0066] Application conditions: solid content of water-coal slurry 68%, addition amount 0.5wt%, storage temperature 50±2℃ (simulating summer storage tank environment).

[0067] Control group: commercially available naphthalene-based dispersant (added amount 0.8 wt %).

[0068] 1.2 Test Method

[0069] Sedimentation rate: Pour the water-coal slurry into the sedimentation column to a height of 400mm, seal it and place it vertically in a constant temperature box at 50±2℃; after standing for 30 days, take out the slurry and slowly pour out the upper liquid, collect the sediment layer at the bottom; dry the sediment at 105℃ to constant weight, and calculate the sedimentation rate:

[0070] Viscosity: Place the coal water slurry sample in a water bath at 25°C for 30 minutes; select a suitable rotor (ensure the torque value is within the range of 10% to 90%) and set the speed to 60 rpm; read the viscosity value (mPa·s) after stabilization, and measure each sample three times and take the average value.

[0071] Fluidity: Pour 500mL of water-coal slurry into the funnel and let it stand for 10 seconds to eliminate bubbles; open the bottom valve and record the time it takes for the slurry to flow out completely (seconds)

[0072] 1.3 Test Results (GB / T 18856-2018)

[0073] index Additive of the present invention (50°C) Naphthalene dispersant (50℃) Initial viscosity (mPa·s) 810±20 1250±50 7-day precipitation rate (%) 1.2 12.5 30-day precipitation rate (%) 3.8 28.3 Liquidity (dumping time / s) 15.3 42.7

[0074] It can be seen that due to the enhanced thermal motion of nanoparticles at high temperatures, the amino-modified SiO2 is firmly adsorbed on the coal surface through hydrogen bonds, forming a dense spatial steric layer; thermal stability of ionic liquids: the phosphate group of H2PO4 still maintains strong complexing ability at high temperatures, inhibiting the Ca 2+ The amount of additives used was reduced by 37.5% (0.5wt% vs 0.8wt%), saving about RMB 24 per ton of coal slurry.

[0075] Example 2: Low temperature fluidity and anti-solidification performance test

[0076] 2.1 Experimental design

[0077] Additive formula: 15 parts of modified nano-SiO2, 40 parts of bio-based dispersant, 10 parts of ionic liquid, and 5 parts of synergist.

[0078] Preparation method:

[0079] Add 10 kg of nano-SiO2 into 100 L of ethanol and stir at 800 rpm to form a uniform suspension;

[0080] 1.5 kg APTES was added dropwise, nitrogen was introduced to remove oxygen, and the temperature was raised to 60°C;

[0081] After 4 h of reaction, the solid was separated using a tubular centrifuge at 8000 rpm and washed with ethanol until the filtrate conductivity was <10 μS / cm;

[0082] The solid material was transferred to a vacuum drying oven and dried until the moisture content was less than 1% to obtain white powdery modified SiO2.

[0083] 10 kg of corn stalks were crushed and mixed with 50 kg of 5 wt% H2SO3 solution, stirred at 80°C for 1 hour, filtered and washed with water;

[0084] The treated straw was treated with 80 kg of 10 wt% NaOH solution in a reactor at 80° C. for 2 hours, and the cellulose filter cake was obtained by filtration;

[0085] Disperse the cellulose filter cake in 200 L of water, add 12 kg of sodium chloroacetate and 3 kg of 30% H2O2;

[0086] Use NaOH to maintain pH = 11, react at 60 ° C for 3 hours;

[0087] The reaction solution was filtered through a plate-and-frame filter press, and the filtrate was neutralized with hydrochloric acid to pH=7, concentrated to a solid content of 30%, and then spray-dried.

[0088] Weigh each component in proportion and disperse them. After dispersion, grind and granulate them.

[0089] Application conditions: solid content of water-coal slurry 65%, addition amount 0.6wt%, storage temperature -20℃ (simulating winter transportation environment).

[0090] Control group: sodium lignin sulfonate (addition amount 1.0 wt%).

[0091] 2.2 Test Method

[0092] Low temperature viscosity: pre-cool the water-coal slurry to -20±0.5℃ and keep warm for 1 hour; set the shear rate to 100s -1 , measure the steady-state viscosity value (mPa·s).

[0093] Fluidity retention rate: Initial fluidity (F0): Determine the pouring time of the freshly prepared slurry according to the method in Example 1; Fluidity after low-temperature standing (F1): Determine the pouring time of the slurry after storing it at -20°C for 15 days and then returning it to 25°C; calculate the retention rate;

[0094] Judgment of solidification phenomenon:

[0095] No solidification: the slurry can flow naturally, and the pouring time is ≤30 seconds;

[0096] Compaction: The slurry cannot be poured out and needs external force to break it up.

[0097] 2.3 Test Results

[0098]

[0099] It can be seen that the freezing point of H2PO4 is as low as -40°C, which reduces the freezing point of the slurry. The ether bond (-O-) of the carboxymethyl cellulose derivative maintains the flexibility of the molecular chain at low temperatures, preventing the hard agglomeration of coal particles and avoiding the toxicity risks of traditional antifreeze agents (such as ethylene glycol).

[0100] Example 3: Improved stability of high solids coal slurry

[0101] 3.1 Experimental design

[0102] Additive formula: 20 parts of modified nano-SiO2, 38 parts of bio-based dispersant, 7 parts of ionic liquid, and 4 parts of synergist.

[0103] Preparation method:

[0104] Add 10 kg of nano-SiO2 into 100 L of ethanol and stir at 800 rpm to form a uniform suspension;

[0105] 1.5 kg APTES was added dropwise, nitrogen was introduced to remove oxygen, and the temperature was raised to 60°C;

[0106] After 4 h of reaction, the solid was separated using a tubular centrifuge at 8000 rpm and washed with ethanol until the filtrate conductivity was <10 μS / cm;

[0107] The solid material was transferred to a vacuum drying oven and dried until the moisture content was less than 1% to obtain white powdery modified SiO2.

[0108] 10 kg of corn stalks were crushed and mixed with 50 kg of 5 wt% H2SO3 solution, stirred at 80°C for 1 hour, filtered and washed with water;

[0109] The treated straw was treated with 80 kg of 10 wt% NaOH solution in a reactor at 80° C. for 2 hours, and the cellulose filter cake was obtained by filtration;

[0110] Disperse the cellulose filter cake in 200 L of water, add 12 kg of sodium chloroacetate and 3 kg of 30% H2O2;

[0111] Use NaOH to maintain pH = 11, react at 60 ° C for 3 hours;

[0112] The reaction solution was filtered through a plate-and-frame filter press, and the filtrate was neutralized with hydrochloric acid to pH=7, concentrated to a solid content of 30%, and then spray-dried.

[0113] Weigh each component in proportion and disperse them. After dispersion, grind and granulate them.

[0114] Application conditions: solid content of water-coal slurry is 72% (super concentrated slurry), addition amount is 0.7wt%, and it is allowed to stand at room temperature (25°C).

[0115] Control group: polycarboxylate dispersant (addition amount 1.2 wt%).

[0116] 3.2 Test Method

[0117] Shear recovery rate:

[0118] Initial viscosity η0: at a shear rate of 10s -1 Measure viscosity under

[0119] High shear failure: applied shear rate 1000s -1 Lasts 5 minutes;

[0120] Recovery test: immediately switch back to 10s -1 , record the viscosity after 5 minutes (η1);

[0121] Calculate the recovery rate: recovery rate = η1 / η0 × 100%;

[0122] Increased calorific value:

[0123] Measure the calorific value of dry coal powder without additives (Q0, MJ / kg); after adding the additive of the present invention, measure the calorific value under the same conditions (Q1); calculate the calorific value improvement rate:

[0124] 3.3 Test Results

[0125]

[0126] It can be seen that the long-chain adsorption of sodium polyaspartate (PASP) reduces friction between coal particles, while trisodium citrate (TSC) neutralizes surface acid sites, reducing viscosity. Furthermore, the additives are free of sulfur and nitrogen impurities, reducing combustion residues. The measured calorific value reaches 28.5 MJ / kg (compared to 27.2 MJ / kg for raw coal). For every 1% increase in solids content, coal transportation costs decrease by approximately 2%. The present invention can achieve stable transportation of 72% solids content.

[0127] Example 4: Comparative analysis of environmental performance and cost

[0128] 4.1 Experimental design

[0129] Additive formula: According to the proportions in Example 1, the annual output of the additive production line is 10,000 tons.

[0130] Control group: traditional petroleum-based dispersant (naphthalene + zinc salt composite system).

[0131]

[0132] It can be seen that the utilization rate of corn straw raw materials is 90%, and each ton of additive consumes 1.2 tons of straw, reducing the pollution caused by burning agricultural waste; the recycling rate of ionic liquid is greater than 85%, and it can be recycled through distillation and recrystallization. 2+ Cr 3+ Not detected, meeting the emission standards of GB 31571-2015; biodegradability (28-day degradation rate > 90%), passed OECD301B certification.

[0133] Example 5: Multi-scenario performance verification

[0134] 5.1 Experimental Design

[0135] Four typical types of coal (lignite, bituminous coal, anthracite, and high-sulfur coal) were selected to compare the performance of the present invention with that of three mainstream additives (naphthalene, lignin, and polycarboxylates).

[0136] 5.2 Test Results

[0137]

[0138]

[0139] It can be seen that the present invention exhibits stable adaptability to different types of coal (from high-volatile lignite to high-hardness anthracite); under extreme temperature (-20°C / 60°C) and high-sulfur coal (sulfur content 3.5%) scenarios, the precipitation rate is only 1 / 5-1 / 7 of that of traditional products; the combustion optimization effect is significant, especially for low-calorific value lignite, which is increased by 5.6%, helping power plants to reduce coal consumption.

[0140] Basis for selecting comparative experimental benchmarks

[0141] Naphthalene dispersants currently have the largest market share (approximately 60%) and represent the performance of mainstream petroleum-based additives.

[0142] Sodium lignin sulfonate is a commonly used bio-based dispersant, which is used to verify that this invention surpasses traditional bio-based technology.

[0143] Polycarboxylates are high-performance synthetic dispersants, and the technical gap between them is

[0144] Zinc salt complex is a typical representative of heavy metal stabilizers, highlighting the environmental advantages

[0145] In summary, the bio-based dispersant prepared from modified nano-SiO2 and corn straw in this invention works synergistically, significantly reducing the sedimentation rate of coal-water slurries through steric hindrance and electrostatic repulsion, extending the stability period, and maintaining good fluidity during long-term storage and transportation. The ionic liquid stabilizer, with its low melting point and high thermal stability, effectively reduces interfacial tension, improves the low-temperature fluidity of coal-water slurries, and prevents particle agglomeration at high temperatures, maintaining stability even at extreme temperatures. The additive can effectively reduce the viscosity of high-solids coal slurries and improve their shear recovery, enabling stable transport even at high solids contents and reducing transportation costs. Replacing traditional petroleum-based dispersants with corn straw reduces raw material costs and mitigates pollution from agricultural waste incineration. Compared to traditional dispersants, the additive requires a lower dosage, further reducing its cost of use. The modified nano-SiO2 acts as a "rigid core" adsorbed on the surface of coal particles, inhibiting sedimentation through steric hindrance; the ionic liquid forms a "flexible shell," reducing interfacial tension and improving low-temperature fluidity. Replacing traditional petroleum-based dispersants with corn straw reduces costs by over 40%. The compound synergist automatically adjusts the slurry pH to 8-9 according to the environment and extends the stability period to 30 days.

[0146] 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, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A coal water slurry additive for preventing precipitation, characterized in that: The invention comprises the following raw materials in parts by weight: 10-20 parts of modified nano silicon dioxide, 30-40 parts of a bio-based dispersant prepared from corn stalks, 5-10 parts of an ionic liquid stabilizer, and 3-5 parts of a compound synergist.

2. The coal water slurry additive for preventing precipitation according to claim 1, characterized in that: The modified nano-silica has a particle size of 20-50 nm and a specific surface area of 200-400 m 2 / g; the ionic liquid stabilizer is 1-butyl-3-methylimidazole dihydrogen phosphate.

3. The coal water slurry additive for preventing precipitation according to claim 1, characterized in that: The compound synergist includes sodium polyaspartate and trisodium citrate, and the ratio of the sodium polyaspartate to the trisodium citrate is 2:

1.

4. A method for preparing the coal water slurry additive for preventing precipitation according to any one of claims 1 to 3, characterized in that: The method comprises: S1: corn straw pretreatment and preparation of modified nano-silica; S2: Weigh each component in proportion and disperse them. After dispersion, grind and granulate them.

5. The method for preparing the coal water slurry additive for preventing precipitation according to claim 4, characterized in that: The preparation of the modified nano-silica comprises: Add 10 kg of nano-SiO2 into 100 L of ethanol and stir at 800 rpm to form a uniform suspension; 1.5 kg APTES was added dropwise, nitrogen was introduced to remove oxygen, and the temperature was raised to 60°C; After 4 h of reaction, the solid was separated using a tubular centrifuge at 8000 rpm and washed with ethanol until the filtrate conductivity was <10 μS / cm; The solid material was transferred to a vacuum drying oven and dried until the moisture content was less than 1% to obtain white powdery modified SiO2.

6. The method for preparing the coal water slurry additive for preventing precipitation according to claim 4, characterized in that: The corn straw pretreatment comprises: 10 kg of corn stalks were crushed and mixed with 50 kg of 5 wt% H2SO3 solution, stirred at 80°C for 1 hour, filtered and washed with water; The treated straw was treated with 80 kg of 10 wt% NaOH solution in a reactor at 80° C. for 2 hours, and the cellulose filter cake was obtained by filtration; Disperse the cellulose filter cake in 200 L of water, add 12 kg of sodium chloroacetate and 3 kg of 30% H2O2; Use NaOH to maintain pH = 11, react at 60 ° C for 3 hours; The reaction solution was filtered through a plate-and-frame filter press, and the filtrate was neutralized with hydrochloric acid to pH=7, concentrated to a solid content of 30%, and then spray-dried.

7. The method for preparing the coal water slurry additive for preventing precipitation according to claim 4, characterized in that: Said S2 further comprises: After weighing each component, add 200L of deionized water and disperse at a speed of 10000rpm.

8. The method for preparing the coal water slurry additive for preventing precipitation according to claim 4, characterized in that: The grinding needs to be performed until the slurry D50 is ≤ 50 μm.

9. The method for preparing a coal water slurry additive for preventing precipitation according to claim 4, characterized in that: The particle size of the finished granules produced by the granulation is 80-100 meshes.

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