A combined filter aid for dehydrating fine-particle coal slime, and its preparation method and application

Abstract

The present invention discloses a combined filter aid for dewatering fine-particle coal slime, as well as its preparation method and application. The filter aid comprises filter aid A, filter aid B, and filter aid C. Filter aid A comprises polyaluminum chloride and polyaluminum sulfate in a mass ratio of 1 to 2.4:1. Filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.4 to 0.8:1. The hydrophobic particles are zeolites surface-modified sequentially with hydrochloric acid and dodecyltrimethoxysilane. Filter aid C is a mixed solution of polyacrylamide and a surfactant in a mass ratio of 0.05 to 0.15:1. The present invention utilizes the synergistic effects of filter aids A, B, and C to efficiently remove moisture from fine-particle coal slime. The method can be used in moderate amounts and effectively shorten the filtration time of the coal slime filter cake.

Description

Technical Field

[0001] The present invention relates to the technical field of coal slime dehydration, in particular to a combined filter aid for fine particle coal slime dehydration, and a preparation method and application thereof. Background Art

[0002] The mine water produced during mining is often accompanied by large amounts of coal slime and mineral particles. At the same time, water flushing is often used to clean working scenes and equipment such as heading shafts, conveyor belts, and roadway surfaces during working face mining. These flushing waters also contain large amounts of solid particles such as coal slime and coal slag. Typically, the above-mentioned mine water and flushing water are collected and collected in underground water tanks. If the coal slime and mineral particles are not cleaned in time, they will not only be deposited in the collection ditch, water tank, and pipes, affecting the water flow rate of the ditch and the volume of the water tank, but will also wear mechanical equipment such as water pumps and lifting pipes, increasing maintenance costs and posing a safety hazard to underground operations. Therefore, it is necessary to efficiently treat the coal slime and mineral particles in underground mine produced water and flushing water.

[0003] Traditional methods for separating coal sludge from water rely primarily on mechanical means, squeezing water out of the coal sludge by applying external force. However, with the increasing mechanization of coal mining operations, the proportion of fine particles in mined coal is also increasing. Mechanical methods alone are therefore difficult to reduce the moisture content of the coal sludge to a low level. Consequently, coal sludge filter aids have been developed to assist mechanical methods in sludge-water separation. Currently, the main filter aids used are surfactants and polyacrylamide. Surfactants disrupt the stabilization system of the coal sludge water, increasing the hydrophobicity of the particles and reducing the moisture content of the coal sludge filter cake. Polyacrylamide promotes the sedimentation of fine particles by forming flocs, thereby improving the settling efficiency of the coal sludge water. However, in actual production, the use of a single filter aid often results in high usage and long filter press times, reducing the efficiency of coal sludge dewatering operations and increasing processing costs. Therefore, it is of practical significance to develop a coal sludge filter aid that has excellent filtration efficacy, can be used in a moderate dosage, and can effectively shorten filter press times. Summary of the Invention

[0004] The present invention aims to overcome the problems of large usage amount and long filter cake filtration time of filter aids for coal slime dehydration in the prior art, and provides a combined filter aid for fine-particle coal slime dehydration, a preparation method and application thereof. Through the synergistic effect of filter aid A, filter aid B and filter aid C, moisture in fine-particle coal slime can be efficiently removed, and the usage amount is moderate, while the filter cake filtration time can be effectively shortened.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B, and filter aid C;

[0007] Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1 to 2.4:1;

[0008] Filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.4 to 0.8:1; the hydrophobic particles are zeolites that are first calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane;

[0009] The filter aid C is a mixed solution of polyacrylamide and a surfactant; the mass ratio of polyacrylamide to the surfactant is 0.05-0.15:1.

[0010] The combined filter aid of the present invention includes filter aid A, filter aid B and filter aid C, wherein the main component of filter aid A is aluminum oxide, and its hydrolysis product is a polyhydroxy aluminum salt compound, which increases its sedimentation velocity by changing the particle potential. The main component of filter aid B is hydrophobic particles of different particle sizes. By adding hydrophobic particles to construct a filter cake pore skeleton and hydrophobic channels, physical means are added to the original chemical filter aid to further reduce the moisture content of the coal slime filter cake; the hydrophobic particles are zeolites that have been sequentially subjected to high-temperature calcination, hydrochloric acid and dodecyltrimethoxysilane surface modification. The high-temperature calcination causes the zeolite particles to undergo dehydroxylation and improve their hydrophobicity. The hydrochloric acid surface modification can increase the SiO2 / Al2O3 ratio to further improve its hydrophobicity. The dodecyltrimethoxysilane surface modification further enhances its surface hydrophobic properties. The surface hydrophobic properties ensure its low moisture content. At the same time, the synergistic effect of different particle sizes can effectively enhance the pore structure of the coal slime filter cake, increase porosity, and reduce its filter press time. The main components of filter aid C are polyacrylamide and surfactant. Polyacrylamide forms larger flocs through a "bridging effect," accelerating the settling of fine particles. The surfactant masks the hydrophilic functional groups on the surface of the coal slime particles while increasing the hydrophobic functional groups, enhancing the hydrophobicity of the particles and reducing the moisture content of the coal slime filter cake. The combination of polyacrylamide and surfactant not only improves the solubility of polyacrylamide but also synergistically aids filtration through two different chemical mechanisms, effectively reducing the moisture content of the coal slime filter cake. The combination of these three filter aids produces a fine-particle coal slime filter aid with excellent filtration performance, moderate usage, and the ability to effectively shorten the filter cake filtration time.

[0011] Preferably, the mass concentration of polyacrylamide in the filter aid C is 0.8-1.2%.

[0012] As a preference, the polyacrylamide in the filter aid C is an anionic polyacrylamide with a molecular weight of 10 to 14 million; the surfactant is a surfactant with a molecular formula of CH3(CH2) 2n+1 A cationic surfactant of N(Br)(CH3)3, wherein the value of n ranges from 5 to 8.

[0013] Preferably, the calcination temperature of the zeolite is 450-550° C., and the calcination time is 1-3 hours.

[0014] In a second aspect, the present invention provides a method for preparing the above-mentioned combined filter aid for dehydrating fine-particle coal slime, comprising the following steps:

[0015] (1) Preparation of filter aid A: Polyaluminium chloride and polyaluminium sulfate are mixed and stirred uniformly in proportion to obtain filter aid A;

[0016] (2) Preparation of filter aid B: crushing natural zeolite and sieving to obtain 100-mesh zeolite particles and 200-mesh zeolite particles; calcining the 100-mesh zeolite particles and the 200-mesh zeolite particles, respectively, and placing them in a hydrochloric acid solution, stirring for reaction, filtering, washing, and drying, cooling to room temperature, and then placing them in an ethanol solution of dodecyltrimethoxysilane, soaking, washing, and drying to obtain 100-mesh hydrophobic particles and 200-mesh hydrophobic particles; mixing the 100-mesh hydrophobic particles and the 200-mesh hydrophobic particles in proportion and stirring uniformly to obtain filter aid B;

[0017] (3) Preparation of filter aid C: Add surfactant and polyacrylamide into water and stir evenly to obtain filter aid C.

[0018] Preferably, in step (1), stirring is performed at a stirring speed of 1000 to 1200 r / min, and the stirring time is 8 to 12 min.

[0019] Preferably, the mass concentration of the hydrochloric acid solution in step (2) is 3-5%, and the calcined 100-mesh zeolite particles and 200-mesh zeolite particles are placed in the hydrochloric acid solution, first stirred at room temperature for 30 minutes, and then stirred in a water bath at 55-65°C for 18-24 hours; filtered and washed, and then dried at 100-110°C for 1-3 hours; the mass concentration of the ethanol solution of dodecyltrimethoxysilane is 5-10%, and after being placed in the ethanol solution of dodecyltrimethoxysilane, ultrasonically vibrated for 20-40 minutes, then soaked at room temperature for 10-24 hours, and dried at 100-110°C for 1-3 hours after washing.

[0020] Preferably, in step (3), the surfactant is first added to water and stirred at a stirring speed of 300 to 400 r / min for 10 to 15 minutes, and then polyacrylamide is added to the solution and stirred at a stirring speed of 300 to 400 r / min for 5 to 10 minutes.

[0021] In a third aspect, the present invention provides an application of the above-mentioned combined filter aid for dehydrating fine-particle coal slime, the steps of which are: first adding filter aid B to the fine-particle coal slime, stirring and reacting, then adding filter aid A, stirring and reacting, adding filter aid C, continuing to stir and react, and then squeezing and dehydrating the fine-particle coal slime; or first adding filter aid A to the fine-particle coal slime, stirring and reacting, then adding filter aid B, stirring and reacting, adding filter aid C, continuing to stir and react, and then squeezing and dehydrating the fine-particle coal slime.

[0022] The order in which filter aid C is added has a significant impact on the filtration effect. Filter aid C enhances particle hydrophobicity by masking hydrophilic groups on the particle surface. It also promotes particle aggregation and increases flocculent formation. If added before filter aids A and B, it will not only increase the moisture content of the coal slime filter cake but also increase the dosage of filter aids A and B. Therefore, filter aid C must be added after filter aids A and B. The order in which filter aids A and B are added has no effect on the filtration effect. Filter aid A primarily alters the surface potential of coal slime particles, destabilizing them and facilitating sedimentation, while filter aids B primarily improve the pore structure of the coal slime by building a physical framework, thereby increasing filtration speed. Filter aids A and B do not interact with each other, so their order of addition has no effect on the filtration effect.

[0023] Preferably, the addition amount of filter aid B is 1-1.5wt% of dry coal slime; the addition amount of filter aid A is 0.09-0.15wt‰ of dry coal slime; the addition amount of polyacrylamide in filter aid C is 0.05-0.1wt‰ of dry coal slime.

[0024] Preferably, the stirring time after adding filter aid B is 1 to 3 minutes; the stirring time after adding filter aid A is 1 to 3 minutes; and the stirring time after adding filter aid C is 5 to 10 minutes.

[0025] Therefore, the present invention has the following beneficial effects:

[0026] (1) The three filter aids with different functions are used together to obtain a fine-particle coal slime filter aid with good filtering effect, moderate usage, and the ability to effectively shorten the coal slime filter cake filtration time;

[0027] (2) Filter aid B adds hydrophobic particles to construct the filter cake pore framework and hydrophobic channels, adding physical filtering aids on the basis of the original chemical filtering aids, further reducing the moisture content of the coal slime filter cake;

[0028] (3) Filter aid C is a combination of polyacrylamide and surfactant, which not only improves the solubility of polyacrylamide, but also synergistically aids filtration through two different chemical mechanisms, effectively reducing the moisture content of the coal slime filter cake. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific embodiments.

[0030] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0031] Overall embodiment:

[0032] A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B, and filter aid C;

[0033] Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1 to 2.4:1;

[0034] Filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.4 to 0.8:1; the hydrophobic particles are zeolites that are first calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane;

[0035] The filter aid C is a mixed solution of polyacrylamide and a surfactant; the mass ratio of polyacrylamide to the surfactant is 0.05-0.15:1.

[0036] As a specific implementation manner, the mass concentration of polyacrylamide in the filter aid C is 0.8-1.2%.

[0037] As a specific embodiment, the polyacrylamide in the filter aid C is an anionic polyacrylamide with a molecular weight of 10 to 14 million; the surfactant is a surfactant with a molecular formula of CH3(CH2) 2n+1 A cationic surfactant of N(Br)(CH3)3, wherein the value of n ranges from 5 to 8; further, the value of n is 7.

[0038] As a specific embodiment, the calcination temperature of the zeolite is 450-550° C., and the calcination time is 1-3 hours.

[0039] The preparation method of the above-mentioned combined filter aid for dehydration of fine-particle coal slime comprises the following steps:

[0040] (1) Preparation of filter aid A: Polyaluminium chloride and polyaluminium sulfate are mixed and stirred uniformly in proportion to obtain filter aid A;

[0041] (2) Preparation of filter aid B: crushing natural zeolite and sieving to obtain 100-mesh zeolite particles and 200-mesh zeolite particles; calcining the 100-mesh zeolite particles and the 200-mesh zeolite particles, respectively, and placing them in a hydrochloric acid solution, stirring for reaction, filtering, washing, and drying, cooling to room temperature, and then placing them in an ethanol solution of dodecyltrimethoxysilane, soaking, washing, and drying to obtain 100-mesh hydrophobic particles and 200-mesh hydrophobic particles; mixing the 100-mesh hydrophobic particles and the 200-mesh hydrophobic particles in proportion and stirring uniformly to obtain filter aid B;

[0042] (3) Preparation of filter aid C: Add surfactant and polyacrylamide into water and stir evenly to obtain filter aid C.

[0043] As a specific implementation manner, in step (1), stirring is performed at a stirring speed of 1000 to 1200 r / min, and the stirring time is 8 to 12 minutes.

[0044] As a specific embodiment, the mass concentration of the hydrochloric acid solution in step (2) is 3-5%. After the calcined 100-mesh zeolite particles and 200-mesh zeolite particles are placed in the hydrochloric acid solution, they are first stirred at room temperature for 30 minutes, and then stirred in a water bath at 55-65°C for 18-24 hours; after filtering and washing, they are dried at 100-110°C for 1-3 hours; the mass concentration of the ethanol solution of dodecyltrimethoxysilane is 5-10%, and after being placed in the ethanol solution of dodecyltrimethoxysilane, they are first ultrasonically vibrated for 20-40 minutes, then soaked at room temperature for 10-24 hours, and dried at 100-110°C for 1-3 hours after washing.

[0045] As a specific embodiment, in step (3), a surfactant is first added to water and stirred at a stirring speed of 300 to 400 r / min for 10 to 15 minutes, and then polyacrylamide is added to the solution and stirred at a stirring speed of 300 to 400 r / min for 5 to 10 minutes.

[0046] The application of the above-mentioned combined filter aid for dehydrating fine-particle coal slime comprises the following steps: first adding filter aid B to the fine-particle coal slime, stirring and reacting, then adding filter aid A, stirring and reacting, adding filter aid C, continuing stirring and reacting, and then squeezing and dehydrating the fine-particle coal slime; or first adding filter aid A to the fine-particle coal slime, stirring and reacting, then adding filter aid B, stirring and reacting, adding filter aid C, continuing stirring and reacting, and then squeezing and dehydrating the fine-particle coal slime.

[0047] As a specific embodiment, the addition amount of filter aid B is 1-1.5wt% of the dry basis coal slime; the addition amount of filter aid A is 0.09-0.15wt‰ of the dry basis coal slime; the addition amount of polyacrylamide in filter aid C is 0.05-0.1wt‰ of the dry basis coal slime.

[0048] As a specific implementation manner, the stirring time after adding filter aid B is 1 to 3 minutes; the stirring time after adding filter aid A is 1 to 3 minutes; and the stirring time after adding filter aid C is 5 to 10 minutes.

[0049] Example 1:

[0050] A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B, and filter aid C;

[0051] Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1.7:1;

[0052] Filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.8:1; the hydrophobic particles are zeolites that have been calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane;

[0053] Filter aid C is a mixed solution of polyacrylamide and surfactant; the mass ratio of polyacrylamide to surfactant is 0.1:1, and the mass concentration of polyacrylamide in the mixed solution is 1.2%; the surfactant has the molecular formula CH3(CH2) 15 The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million.

[0054] The preparation method of the above-mentioned combined filter aid for dehydration of fine-particle coal slime comprises the following steps:

[0055] (1) Preparation of filter aid A: Polyaluminium chloride and polyaluminium sulfate in the formula mass ratio were added in sequence into a stirring device and thoroughly mixed at a stirring speed of 1100 r / min for 10 min to obtain filter aid A;

[0056] (2) Preparation of filter aid B: crush the natural zeolite and sieve it with a sieve of corresponding mesh size to obtain 100 mesh zeolite particles and 200 mesh zeolite particles; then place the zeolite particles of each particle size in a muffle furnace, heat it to 500°C at a heating rate of 10°C / min and keep it warm for 2 hours, wait for it to cool to room temperature, put it into a hydrochloric acid solution with a mass concentration of 3.65%, stir it at room temperature for 30 minutes, place it in a 60°C water bath and stir it for 24 hours, then filter and rinse it, and check it with AgNO3 until no white precipitate is generated in the cleaning solution, and then place it in a drying oven. The filter aid B was prepared by drying the filter particles at 105°C in an oven for 2 hours; after cooling to room temperature, the filter particles were placed in an ethanol solution of 8% dodecyltrimethoxysilane by mass, ultrasonically shaken for 30 minutes, and then soaked at room temperature for 12 hours. The filter particles were washed several times with anhydrous ethanol and then dried in an oven at 105°C for 2 hours to obtain 100-mesh hydrophobic particles and 200-mesh hydrophobic particles; the 100-mesh hydrophobic particles and 200-mesh hydrophobic particles were added to a stirring device in the same mass ratio and mixed thoroughly at a stirring speed of 600 r / min for 4 minutes to obtain filter aid B;

[0057] (3) Preparation of filter aid C: The surfactant was dissolved in 1 L of water and stirred at a stirring speed of 350 r / min for 15 min. Then, polyacrylamide was added to the solution and stirred at a stirring speed of 350 r / min for 10 min to obtain filter aid C.

[0058] Example 2:

[0059] A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B, and filter aid C;

[0060] Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 2.4:1;

[0061] Filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.6:1; the hydrophobic particles are zeolites that are first calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane;

[0062] Filter aid C is a mixed solution of polyacrylamide and surfactant; the mass ratio of polyacrylamide to surfactant is 0.1:1, and the mass concentration of polyacrylamide in the mixed solution is 0.8%; the surfactant has the molecular formula CH3(CH2) 15 The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million.

[0063] The preparation method of the above-mentioned combined filter aid for dehydration of fine-particle coal slime comprises the following steps:

[0064] (1) Preparation of filter aid A: Polyaluminium chloride and polyaluminium sulfate in the formula mass ratio were added sequentially into a stirring device and thoroughly mixed at a stirring speed of 1000 r / min for 12 min to obtain filter aid A;

[0065] (2) Preparation of filter aid B: crush the natural zeolite and sieve it with a sieve of corresponding mesh size to obtain 100 mesh zeolite particles and 200 mesh zeolite particles; then place the zeolite particles of each particle size in a muffle furnace, heat it to 500°C at a heating rate of 10°C / min and keep it warm for 2 hours, wait for it to cool to room temperature, put it into a hydrochloric acid solution with a mass concentration of 3.65%, stir it at room temperature for 30 minutes, place it in a 60°C water bath and stir it for 24 hours, then filter and rinse it, and check it with AgNO3 until no white precipitate is generated in the cleaning solution, and then place it in a drying oven. The filter aid B was prepared by drying the filter particles at 105° C. in an oven for 2 hours; after cooling to room temperature, the filter particles were placed in an ethanol solution of 8% by mass of dodecyltrimethoxysilane, ultrasonically shaken for 30 minutes, and then soaked at room temperature for 12 hours. The filter particles were washed several times with anhydrous ethanol and then dried in an oven at 105° C. for 2 hours to obtain 100-mesh hydrophobic particles and 200-mesh hydrophobic particles; the 100-mesh hydrophobic particles and 200-mesh hydrophobic particles were added to a stirring device in the same mass ratio and mixed thoroughly at a stirring speed of 500 r / min for 5 minutes to obtain filter aid B;

[0066] (3) Preparation of filter aid C: The surfactant was dissolved in 1 L of water and stirred at a stirring speed of 300 r / min for 15 min. Then, polyacrylamide was added to the solution and stirred at a stirring speed of 300 r / min for 10 min to obtain filter aid C.

[0067] Example 3:

[0068] A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B, and filter aid C;

[0069] Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1:1;

[0070] Filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.6:1; the hydrophobic particles are zeolites that are first calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane;

[0071] Filter aid C is a mixed solution of polyacrylamide and surfactant; the mass ratio of polyacrylamide to surfactant is 0.1:1, and the mass concentration of polyacrylamide in the mixed solution is 0.8%; the surfactant has the molecular formula CH3(CH2) 15The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million.

[0072] The preparation method of the above-mentioned combined filter aid for dehydration of fine-particle coal slime comprises the following steps:

[0073] (1) Preparation of filter aid A: Polyaluminium chloride and polyaluminium sulfate in the formula mass ratio were added in sequence into a stirring device and thoroughly mixed at a stirring speed of 1200 r / min for 8 min to obtain filter aid A;

[0074] (2) Preparation of filter aid B: crush the natural zeolite and sieve it with a sieve of corresponding mesh size to obtain 100 mesh zeolite particles and 200 mesh zeolite particles; then place the zeolite particles of each particle size in a muffle furnace, heat it to 500°C at a heating rate of 10°C / min and keep it warm for 2 hours, wait for it to cool to room temperature, put it into a hydrochloric acid solution with a mass concentration of 3.65%, stir it at room temperature for 30 minutes, place it in a 60°C water bath and stir it for 24 hours, then filter and rinse it, and check it with AgNO3 until no white precipitate is generated in the cleaning solution, and then place it in a drying oven. The filter aid B was obtained by drying the filter particles at 105°C in an oven for 2 hours; after cooling to room temperature, the filter particles were placed in an ethanol solution of 8% by mass of dodecyltrimethoxysilane, ultrasonically shaken for 30 minutes, and then soaked at room temperature for 12 hours. The filter particles were washed several times with anhydrous ethanol and then dried in an oven at 105°C for 2 hours to obtain 100-mesh hydrophobic particles and 200-mesh hydrophobic particles; the 100-mesh hydrophobic particles and 200-mesh hydrophobic particles were added to a stirring device in the same mass ratio and mixed thoroughly at a stirring speed of 800 r / min for 3 minutes to obtain filter aid B;

[0075] (3) Preparation of filter aid C: The surfactant was dissolved in 1 L of water and stirred at a stirring speed of 400 r / min for 10 min. Then, polyacrylamide was added to the solution and stirred at a stirring speed of 400 r / min for 5 min to obtain filter aid C.

[0076] Example 4:

[0077] A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B, and filter aid C;

[0078] Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1:1;

[0079] Filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.4:1; the hydrophobic particles are zeolites that have been calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane;

[0080] Filter aid C is a mixed solution of polyacrylamide and surfactant; the mass ratio of polyacrylamide to surfactant is 0.1:1, and the mass concentration of polyacrylamide in the mixed solution is 0.8%; the surfactant has the molecular formula CH3(CH2) 15 The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million;

[0081] The preparation method is the same as in Example 1.

[0082] Example 5:

[0083] A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B, and filter aid C;

[0084] Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1.7:1;

[0085] Filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.4:1; the hydrophobic particles are zeolites that have been calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane;

[0086] Filter aid C is a mixed solution of polyacrylamide and surfactant; the mass ratio of polyacrylamide to surfactant is 0.1:1, and the mass concentration of polyacrylamide in the mixed solution is 1%; the surfactant has the molecular formula CH3(CH2) 15 The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million;

[0087] The preparation method is the same as in Example 1.

[0088] Example 6:

[0089] A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B, and filter aid C;

[0090] Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 2.4:1;

[0091] Filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.8:1; the hydrophobic particles are zeolites that have been calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane;

[0092] Filter aid C is a mixed solution of polyacrylamide and surfactant; the mass ratio of polyacrylamide to surfactant is 0.1:1, and the mass concentration of polyacrylamide in the mixed solution is 1%; the surfactant has the molecular formula CH3(CH2) 15The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million;

[0093] The preparation method is the same as in Example 1.

[0094] Comparative Example 1:

[0095] The difference between Comparative Example 1 and Example 1 is that only filter aid A is used as the filter aid; the formula and preparation method of filter aid A are the same as those in Example 1.

[0096] Comparative Example 2:

[0097] The difference between Comparative Example 2 and Example 1 is that only filter aid B is used as the filter aid; the formula and preparation method of filter aid B are the same as those in Example 1.

[0098] Comparative Example 3:

[0099] The difference between Comparative Example 3 and Example 1 is that only filter aid C is used as the filter aid; the formula and preparation method of filter aid C are the same as those in Example 1.

[0100] Comparative Example 4:

[0101] The difference between Comparative Example 4 and Example 1 is that the filter aids only include filter aids A and filter aids B, and do not include filter aid C; the formula and preparation method of filter aids A and filter aids B are the same as those in Example 1.

[0102] Comparative Example 5:

[0103] The difference between Comparative Example 5 and Example 1 is that the filter aids only include filter aids A and filter aids C, and do not include filter aid B; the formula and preparation method of filter aids A and filter aids C are the same as those in Example 1.

[0104] Comparative Example 6:

[0105] The difference between Comparative Example 6 and Example 1 is that the filter aids only include filter aids B and filter aids C, and do not include filter aid A; the formula and preparation method of filter aids B and filter aids C are the same as those in Example 1.

[0106] Comparative Example 7:

[0107] The difference between Comparative Example 7 and Example 1 is that filter aid B uses only 100-mesh hydrophobic particles, and the rest is the same as in Example 1.

[0108] Comparative Example 8:

[0109] The difference between Comparative Example 8 and Example 1 is that filter aid B only uses 200-mesh hydrophobic particles, and the rest is the same as in Example 1.

[0110] Comparative Example 9:

[0111] The difference between Comparative Example 9 and Example 1 is that the preparation method of filter aid B is as follows: natural zeolite is crushed and sieved with a corresponding mesh screen to obtain 100 mesh zeolite particles and 200 mesh zeolite particles; then, the zeolite particles of each particle size are placed in a muffle furnace, heated to 500°C at a heating rate of 10°C / min and kept warm for 2h, and after cooling to room temperature, placed in a hydrochloric acid solution with a mass concentration of 3.65%, stirred at room temperature for 30min, placed in a 60°C water bath and stirred for 24h, then filtered and rinsed, and tested with AgNO3 until no white precipitate is generated in the cleaning liquid, and then placed in an oven at 105°C for 2 hours; 100 mesh hydrophobic particles and 200 mesh hydrophobic particles are obtained; 100 mesh hydrophobic particles and 200 mesh hydrophobic particles of the formula mass ratio are added to the stirring apparatus in sequence, and mixed thoroughly at a stirring speed of 600r / min for 4min to obtain filter aid B; the rest are the same as in Example 1.

[0112] Comparative Example 10:

[0113] The difference between Comparative Example 10 and Example 1 is that the filter aid C is a polyacrylamide solution; the rest is the same as in Example 1.

[0114] Comparative Example 11:

[0115] The difference between Comparative Example 11 and Example 1 is that the filter aid C is a surfactant solution; the rest is the same as in Example 1.

[0116] Application examples:

[0117] The filter aids in the above examples and comparative examples were applied to the dewatering of fine-particle coal slime. The specific method is as follows:

[0118] First, add filter aid B to the fine-particle coal slime water, stir thoroughly to mix the coal slime and filter aid B, and the stirring time is 2 minutes; then add filter aid A to the fine-particle coal slime water, stir thoroughly to allow filter aid A to react with the coal slime, and the stirring time is 1 minute; then add filter aid C, stir thoroughly to allow filter aid C to react with the coal slime, and the stirring time is 5 minutes; finally, send it into the diaphragm filter press through a high-pressure pump for squeezing and dehydration.

[0119] The dosage of filter aid A, filter aid B and filter aid C in each application example and the moisture content of the dehydrated coal slime filter cake are shown in Table 1.

[0120] Table 1: Filter aid dosage and dehydration effect.

[0121]

[0122] As can be seen from Table 1, the combined filter aids of the present invention were used in Examples 1-6, and the dehydrated coal slime had a moisture content of 16.37% to 19.08%. However, in Comparative Examples 1-6, only one or two of Filter A, Filter B, or Filter C were used, and the dehydration efficiency of the coal slime decreased compared to Example 1. In Comparative Examples 7 and 8, Filter Aid B used only hydrophobic particles of a single particle size, and the dehydration efficiency of the coal slime also decreased compared to Example 1. In Comparative Example 9, Filter Aid B was not modified with dodecyltrimethoxysilane, resulting in a decrease in its surface hydrophobicity and a reduction in the dehydration efficiency of the coal slime. In Comparative Examples 10 and 11, Filter Aid C used only polyacrylamide or a surfactant, and the dehydration efficiency of the coal slime did not reach the level of the examples.

Claims

1. A combined filter aid for dehydrating fine-particle coal slime, characterized in that: Including filter aid A, filter aid B and filter aid C; Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1 to 2.4:1; Filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.4 to 0.8:1; the hydrophobic particles are zeolites that are first calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane; Filter aid C is a mixed solution of polyacrylamide and a surfactant; the mass ratio of polyacrylamide to surfactant is 0.05~0.15:

1.

2. The combined filter aid for dehydrating fine-particle coal slime according to claim 1, characterized in that: The mass concentration of polyacrylamide in filter aid C is 0.8~1.2%; the polyacrylamide in filter aid C is anionic polyacrylamide with a molecular weight of 10 million to 14 million; the surfactant is selected from the molecular formula CH3(CH2) 2n+1 A cationic surfactant of N(Br)(CH3)3, wherein the value of n ranges from 5 to 8.

3. The combined filter aid for dehydrating fine-particle coal slime according to claim 1, characterized in that: The calcination temperature of zeolite is 450~550℃, and the calcination time is 1~3h.

4. A method for preparing a combined filter aid for dehydrating fine-particle coal slime according to any one of claims 1 to 3, characterized in that: The steps include: (1) Preparation of filter aid A: Polyaluminium chloride and polyaluminium sulfate are mixed and stirred uniformly in proportion to obtain filter aid A; (2) Preparation of filter aid B: crushing natural zeolite and sieving to obtain 100-mesh zeolite particles and 200-mesh zeolite particles; calcining the 100-mesh zeolite particles and the 200-mesh zeolite particles, respectively, and placing them in a hydrochloric acid solution, stirring for reaction, filtering, washing, and drying, cooling to room temperature, and then placing them in an ethanol solution of dodecyltrimethoxysilane, soaking, washing, and drying to obtain 100-mesh hydrophobic particles and 200-mesh hydrophobic particles; mixing the 100-mesh hydrophobic particles and the 200-mesh hydrophobic particles in proportion and stirring evenly to obtain filter aid B; (3) Preparation of filter aid C: Add surfactant and polyacrylamide to water and stir evenly to obtain filter aid C.

5. The method for preparing a combined filter aid for dehydrating fine-particle coal slime according to claim 4, characterized in that: In step (1), stirring is performed at a stirring speed of 1000-1200 r / min, and the stirring time is 8-12 min.

6. The method for preparing a combined filter aid for dehydrating fine-particle coal slime according to claim 4, wherein: The mass concentration of the hydrochloric acid solution in step (2) is 3-5%. After placing the calcined 100-mesh zeolite particles and 200-mesh zeolite particles in the hydrochloric acid solution, stir at room temperature for 30 minutes, and then stir in a water bath at 55-65°C for 18-24 hours; After filtering and washing, it is dried at 100~110℃ for 1~3h; the mass concentration of the ethanol solution of dodecyltrimethoxysilane is 5~10%. After being placed in the ethanol solution of dodecyltrimethoxysilane, it is first ultrasonically shaken for 20~40min, and then soaked at room temperature for 10~24h. After washing, it is dried at 100~110℃ for 1~3h.

7. The method for preparing a combined filter aid for dehydrating fine-particle coal slime according to claim 4, wherein: In step (3), the surfactant is first added to the water, and the solution is stirred at a stirring speed of 300-400 r / min for 10-15 min. Then, polyacrylamide is added to the solution, and the solution is stirred at a stirring speed of 300-400 r / min for 5-10 min.

8. A use of the combined filter aid for dehydrating fine coal slime according to any one of claims 1 to 3, characterized in that the steps are: first adding filter aid B to the fine coal slime, stirring and reacting, then adding filter aid A, stirring and reacting, adding filter aid C, continuing stirring and reacting, and then squeezing and dehydrating the fine coal slime; or first adding filter aid A to the fine coal slime, stirring and reacting, then adding filter aid B, stirring and reacting, adding filter aid C, continuing stirring and reacting, and then squeezing and dehydrating the fine coal slime.

9. The use of the combined filter aid for dehydration of fine-particle coal slime according to claim 8, characterized in that: The addition amount of filter aid B is 1~1.5wt% of the dry basis coal slime; the addition amount of filter aid A is 0.09~0.15wt‰ of the dry basis coal slime; the addition amount of polyacrylamide in filter aid C is 0.05~0.1wt‰ of the dry basis coal slime.

10. The use of the combined filter aid for dehydration of fine-particle coal slime according to claim 8, characterized in that: The stirring time after adding filter aid B is 1 to 3 minutes; the stirring time after adding filter aid A is 1 to 3 minutes; the stirring time after adding filter aid C is 5 to 10 minutes.

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