Combined filter aid for dewatering fine-particle coal slime as well as preparation method and application of combined filter aid

Abstract

The invention discloses a combined filter aid for dewatering fine-particle coal slime as well as a preparation method and application of the combined filter aid. The combined filter aid comprises a filter aid A, a filter aid B and a filter aid C, the filter aid A comprises polyaluminum chloride and polyaluminum sulfate in a mass ratio of (1-2.4): 1; the filter aid B comprises 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of (0.4-0.8): 1; the hydrophobic particles are zeolite subjected to surface modification by hydrochloric acid and dodecyl trimethoxy silane in sequence; the filter aid C is a mixed solution of polyacrylamide and a surfactant; the mass ratio of the polyacrylamide to the surfactant is (0.05-0.15): 1. Through the synergistic effect of the filter aid A, the filter aid B and the filter aid C, water in fine-particle coal slime can be efficiently removed, the use amount is moderate, and meanwhile, the filter pressing time of a coal slime filter cake can be effectively shortened.

Description

Technical Field

[0001] The invention relates to the technical field of coal slime dehydration, and 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 the mining process is often accompanied by a large amount of coal slime and mineral particles. At the same time, water flushing is often used to clean the working scenes and equipment such as the heading shaft, conveyor belts, and tunnel surfaces during the working face mining process. These flushing waters also contain a large amount of solid particles such as coal slime and coal ash. Usually, the above-mentioned mine water and flushing water will be collected and merged into the underground water tank. If the coal slime and mineral particles are not cleaned in time, they will not only be deposited in the sump, water tank and pipes, affecting the water flow rate of the ditch and the volume of the water tank, but also will wear mechanical equipment such as water pumps and lifting pipelines, increase maintenance costs and underground safety operation hazards. Therefore, it is necessary to efficiently treat the coal slime and mineral particles in the produced water and flushing water of underground mines.

[0003] Traditional means of mud-water separation are mainly mechanical means, which squeeze out the water in the coal slime by applying external force. However, with the improvement of the mechanization degree of coal mine operations, the proportion of fine particles in the mined coal is also increasing. It is difficult to reduce the moisture content in the coal slime to a low level by mechanical means alone. Therefore, people have developed coal slime filter aids to assist mechanical means in mud-water separation operations. At present, the main filter aids used are surfactants and polyacrylamide. The former destroys the stable system of coal slime water and improves the hydrophobicity of particles to reduce the moisture content of coal slime filter cakes. The latter promotes the sedimentation of fine particles by forming flocs and improves the sedimentation efficiency of coal slime water. However, in the actual production process, a single filter aid has problems such as large usage and long filter pressing time of coal slime filter cakes, which reduces the efficiency of coal slime dehydration operations and increases the processing cost of enterprises. Therefore, it is of practical significance to prepare a coal slime filter aid with good filtering effect, moderate usage and effective shortening of filter pressing time of coal slime filter cakes. Summary of the invention

[0004] The present invention aims to overcome the problems of large usage amount and long filtration time of coal slime filter cake in the prior art of filter aids for coal slime dehydration, and provides a combined filter aid for fine-particle coal slime dehydration and 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, and the filtration time of coal slime filter cake can be effectively shortened.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: 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; The filter aid A comprises polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1 to 2.4:1; The 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 in sequence; 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.

[0006] 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, and its sedimentation velocity is increased by changing the particle potential. The main component of filter aid B is hydrophobic particles of different particle sizes, and the filter cake pore skeleton and hydrophobic channels are constructed by adding hydrophobic particles, and physical means are added to the original chemical means to further reduce the moisture content of the coal slime filter cake; the hydrophobic particles are zeolites that have been subjected to high-temperature calcination, hydrochloric acid and dodecyltrimethoxysilane surface modification in sequence, and the high-temperature calcination causes the zeolite particles to undergo dehydroxylation to improve their hydrophobicity, and the hydrochloric acid surface modification can increase the ratio of SiO2 / Al2O3 to further improve its hydrophobicity, and the dodecyltrimethoxysilane surface modification further enhances its surface hydrophobicity, and the surface hydrophobicity ensures its lower moisture content, and the synergistic effect of different particle sizes can effectively enhance the pore structure of the coal slime filter cake, increase the porosity, and reduce its filter pressing time. The main components of filter aid C are polyacrylamide and surfactant. Polyacrylamide forms larger flocs through "bridging effect" to accelerate the sedimentation process of fine particles. Surfactants mask the hydrophilic functional groups on the surface of coal slime particles and increase the hydrophobic functional groups at the same time, thereby enhancing the hydrophobicity of particles and reducing the water content of coal slime filter cakes. The combination of polyacrylamide and surfactant not only improves the solubility of polyacrylamide, but also synergizes filtering through two different chemical mechanisms, effectively reducing the water content of coal slime filter cakes. Through the combination of the three filter aids, a fine-particle coal slime filter aid with good filtering effect, moderate usage and effective shortening of the coal slime filter cake filtration time can be obtained.

[0007] Preferably, the mass concentration of polyacrylamide in the filter aid C is 0.8-1.2%.

[0008] As a preferred 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.

[0009] Preferably, the calcination temperature of the zeolite is 450-550° C., and the calcination time is 1-3 hours.

[0010] 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: (1) preparing filter aid A: mixing polyaluminium chloride and polyaluminium sulfate in proportion and stirring evenly to obtain filter aid A; (2) preparing filter aid B: crushing natural zeolite and sieving it to obtain 100-mesh zeolite particles and 200-mesh zeolite particles; calcining the 100-mesh zeolite particles and the 200-mesh zeolite particles respectively, placing them in a hydrochloric acid solution, stirring them for reaction, filtering, washing, and drying them, cooling them to room temperature, and then placing them in an ethanol solution of dodecyltrimethoxysilane, soaking them, washing, and drying them 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 them uniformly to obtain filter aid B; (3) Preparation of filter aid C: Add surfactant and polyacrylamide into water and stir evenly to obtain filter aid C.

[0011] 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.

[0012] Preferably, 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, 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%. After being placed in the ethanol solution of dodecyltrimethoxysilane, they are first ultrasonically shaken for 20-40 minutes, and then soaked at room temperature for 10-24 hours, and after washing, they are dried at 100-110° C. for 1-3 hours.

[0013] 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 min, and then polyacrylamide is added to the solution, and stirring is continued at a stirring speed of 300 to 400 r / min for 5 to 10 min.

[0014] 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 the reaction, then adding filter aid A, stirring the reaction, adding filter aid C, continuing to stir the reaction, and squeezing and dehydrating the fine-particle coal slime; or first adding filter aid A to the fine-particle coal slime, stirring the reaction, then adding filter aid B, stirring the reaction, adding filter aid C, continuing to stir the reaction, and squeezing and dehydrating the fine-particle coal slime.

[0015] The order of adding filter aid C has a great influence on the filtering effect. On the one hand, filter aid C enhances the hydrophobicity of particles by masking the hydrophilic groups on the surface of particles. On the other hand, it also plays a role in particle coagulation and enlargement of floccules. If it is added before filter aids A and B, it will not only lead to an increase in the moisture content of the coal slime filter cake, but also increase the dosage of filter aids A and B. Therefore, the order of adding filter aid C must be after filter aids A and B. The order of adding filter aids A and B has no effect on the filtering effect; the main function of filter aid A is to change the surface potential of coal slime particles, making them unstable and easy to settle, while the main function of filter aid is to improve the pore structure of coal slime by constructing a physical skeleton and increase the filtration speed. There is no interaction between filter aids A and B, so the order of their addition has no effect on the filtering effect.

[0016] Preferably, the added amount of filter aid B is 1-1.5wt% of the dry basis coal slime; the added amount of filter aid A is 0.09-0.15wt‰ of the dry basis coal slime; the added amount of polyacrylamide in filter aid C is 0.05-0.1wt‰ of the dry basis coal slime.

[0017] 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.

[0018] Therefore, the present invention has the following beneficial effects: (1) The three filter aids with different functions are used together to obtain a fine-particle coal slime filter aid with good filter effect, moderate usage and effective shortening of the coal slime filter cake filtration time; (2) Filter aid B adds hydrophobic particles to construct the filter cake pore framework and hydrophobic channels, adding physical filtering aids to the original chemical filtering aids, further reducing the moisture content of the coal slime filter cake; (3) Filter aid C is a combination of polyacrylamide and surfactant, which not only improves the solubility of polyacrylamide, but also synergizes filtering through two different chemical mechanisms, effectively reducing the moisture content of the coal slime filter cake. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with specific implementation methods.

[0020] 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 conventional methods in the art.

[0021] Overall embodiment: A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B and filter aid C; The filter aid A comprises polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1 to 2.4:1; The 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 in sequence; 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.

[0022] As a specific implementation, the mass concentration of polyacrylamide in the filter aid C is 0.8-1.2%.

[0023] As a specific implementation method, 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.

[0024] As a specific implementation manner, the calcination temperature of the zeolite is 450-550° C., and the calcination time is 1-3 hours.

[0025] The method for preparing the above-mentioned combined filter aid for dehydrating fine particle coal slime comprises the following steps: (1) preparing filter aid A: mixing polyaluminium chloride and polyaluminium sulfate in proportion and stirring evenly to obtain filter aid A; (2) preparing filter aid B: crushing natural zeolite and sieving it to obtain 100-mesh zeolite particles and 200-mesh zeolite particles; calcining the 100-mesh zeolite particles and the 200-mesh zeolite particles respectively, placing them in a hydrochloric acid solution, stirring them for reaction, filtering, washing, and drying them, cooling them to room temperature, and then placing them in an ethanol solution of dodecyltrimethoxysilane, soaking them, washing, and drying them 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 them uniformly to obtain filter aid B; (3) Preparation of filter aid C: Add surfactant and polyacrylamide into water and stir evenly to obtain filter aid C.

[0026] 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 min.

[0027] As a specific implementation method, 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, 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%. After being placed in the ethanol solution of dodecyltrimethoxysilane, they are first ultrasonically shaken for 20-40 minutes, and then soaked at room temperature for 10-24 hours, and then dried at 100-110° C. for 1-3 hours after washing.

[0028] As a specific implementation method, 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 stirring is continued at a stirring speed of 300 to 400 r / min for 5 to 10 minutes.

[0029] The application of the above-mentioned combined filter aid for dehydrating fine-particle coal slime comprises the following steps: firstly add filter aid B to the fine-particle coal slime, stir and react, then add filter aid A, stir and react, add filter aid C, continue stirring and react, and then squeeze and dehydrate the fine-particle coal slime; or firstly add filter aid A to the fine-particle coal slime, stir and react, then add filter aid B, stir and react, add filter aid C, continue stirring and react, and then squeeze and dehydrate the fine-particle coal slime.

[0030] As a specific implementation, 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.

[0031] 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.

[0032] Embodiment 1: A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B and filter aid C; Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1.7:1; Filter aid B includes 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.8:1; the hydrophobic particles are zeolites that are first calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane in sequence; 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 a molecular formula of CH3(CH2) 15 The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million.

[0033] The method for preparing the above-mentioned combined filter aid for dehydrating fine particle coal slime comprises the following steps: (1) Preparation of filter aid A: Adding polyaluminium chloride and polyaluminium sulfate in a formula mass ratio in a stirring device in sequence, and mixing them thoroughly at a stirring speed of 1100 r / min for 10 min to obtain filter aid A; (2) Preparation of filter aid B: crushing natural zeolite and sieving with a sieve of corresponding mesh number to obtain 100 mesh zeolite particles and 200 mesh zeolite particles; then placing the zeolite particles of each particle size in a muffle furnace, heating the temperature to 500°C at a rate of 10°C / min and keeping the temperature for 2 h, and after cooling to room temperature, placing them in a hydrochloric acid solution with a mass concentration of 3.65%, stirring at room temperature for 30 min, placing them in a 60°C water bath and stirring for 24 h, then filtering and rinsing, and checking with AgNO3 until no white precipitate is generated in the cleaning solution, and placing them in a drying oven. The obtained particles were dried in an oven at 105°C for 2 hours; after cooling to room temperature, the 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. After being washed several times with anhydrous ethanol, the particles were placed in an oven at 105°C for 2 hours to obtain 100-mesh hydrophobic particles and 200-mesh hydrophobic particles; 100-mesh hydrophobic particles and 200-mesh hydrophobic particles of the formula mass ratio were added to a stirring device in sequence, and the particles were fully mixed at a stirring speed of 600 r / min for 4 minutes to obtain filter aid B; (3) Preparation of filter aid C: The surfactant was dissolved in 1 L of water, and the mixture was stirred at a stirring speed of 350 r / min for 15 min. Then, polyacrylamide was added to the solution, and the mixture was stirred at a stirring speed of 350 r / min for 10 min to obtain filter aid C.

[0034] Embodiment 2: A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B and filter aid C; Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 2.4:1; Filter aid B includes 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 in sequence; 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 a molecular formula of CH3(CH2) 15 The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million.

[0035] The method for preparing the above-mentioned combined filter aid for dehydrating fine particle coal slime comprises the following steps: (1) Preparation of filter aid A: Adding polyaluminium chloride and polyaluminium sulfate in a formula mass ratio in sequence into a stirring device, and mixing them thoroughly at a stirring speed of 1000 r / min for 12 min to obtain filter aid A; (2) Preparation of filter aid B: crushing natural zeolite and sieving with a sieve of corresponding mesh number to obtain 100 mesh zeolite particles and 200 mesh zeolite particles; then placing the zeolite particles of each particle size in a muffle furnace, heating the temperature to 500°C at a rate of 10°C / min and keeping the temperature for 2 h, and after cooling to room temperature, placing them in a hydrochloric acid solution with a mass concentration of 3.65%, stirring at room temperature for 30 min, placing them in a 60°C water bath and stirring for 24 h, then filtering and rinsing, and checking with AgNO3 until no white precipitate is generated in the cleaning solution, and placing them in a drying oven. The filter material was dried in an oven at 105°C for 2 hours; after cooling to room temperature, it was placed in an ethanol solution of 8% dodecyltrimethoxysilane by mass, ultrasonically shaken for 30 minutes, soaked at room temperature for 12 hours, washed with anhydrous ethanol for several times, and then placed in an oven at 105°C for 2 hours to obtain 100-mesh hydrophobic particles and 200-mesh hydrophobic particles; 100-mesh hydrophobic particles and 200-mesh hydrophobic particles of the formula mass ratio were added to the stirring device in sequence, and fully mixed at a stirring speed of 500r / min for 5 minutes to obtain filter aid B; (3) Preparation of filter aid C: The surfactant was dissolved in 1 L of water, and the mixture was stirred at a stirring speed of 300 r / min for 15 min. Then, polyacrylamide was added to the solution, and the mixture was stirred at a stirring speed of 300 r / min for 10 min to obtain filter aid C.

[0036] Embodiment 3: A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B and filter aid C; Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1:1; Filter aid B includes 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 in sequence; 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 a molecular formula of CH3(CH2) 15 The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million.

[0037] The method for preparing the above-mentioned combined filter aid for dehydrating fine particle coal slime comprises the following steps: (1) Preparation of filter aid A: Adding polyaluminium chloride and polyaluminium sulfate in a formula mass ratio in a stirring device in sequence, and mixing them thoroughly at a stirring speed of 1200 r / min for 8 min to obtain filter aid A; (2) Preparation of filter aid B: crushing natural zeolite and sieving with a sieve of corresponding mesh number to obtain 100 mesh zeolite particles and 200 mesh zeolite particles; then placing the zeolite particles of each particle size in a muffle furnace, heating the temperature to 500°C at a rate of 10°C / min and keeping the temperature for 2 h, and after cooling to room temperature, placing them in a hydrochloric acid solution with a mass concentration of 3.65%, stirring at room temperature for 30 min, placing them in a 60°C water bath and stirring for 24 h, then filtering and rinsing, and checking with AgNO3 until no white precipitate is generated in the cleaning solution, and placing them 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% dodecyltrimethoxysilane by mass, ultrasonically shaken for 30 minutes, and then soaked at room temperature for 12 hours. After washing with anhydrous ethanol for several times, the filter particles were placed in an oven for drying 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 of the formula mass ratio were added to the stirring device in sequence, and the mixture was fully mixed at a stirring speed of 800 r / min for 3 minutes to obtain filter aid B; (3) Preparation of filter aid C: The surfactant was dissolved in 1 L of water, and the mixture was stirred at a stirring speed of 400 r / min for 10 min. Then, polyacrylamide was added to the solution, and the mixture was stirred at a stirring speed of 400 r / min for 5 min to obtain filter aid C.

[0038] Embodiment 4: A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B and filter aid C; Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1:1; Filter aid B includes 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.4:1; the hydrophobic particles are zeolites that are first calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane in sequence; 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 a molecular formula of CH3(CH2) 15 The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million; The preparation method is the same as in Example 1.

[0039] Embodiment 5: A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B and filter aid C; Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 1.7:1; Filter aid B includes 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.4:1; the hydrophobic particles are zeolites that are first calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane in sequence; 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 a molecular formula of CH3(CH2) 15 The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million; The preparation method is the same as in Example 1.

[0040] Embodiment 6: A combined filter aid for dehydrating fine-particle coal slime, comprising filter aid A, filter aid B and filter aid C; Filter aid A includes polyaluminium chloride and polyaluminium sulfate in a mass ratio of 2.4:1; Filter aid B includes 100-mesh hydrophobic particles and 200-mesh hydrophobic particles in a mass ratio of 0.8:1; the hydrophobic particles are zeolites that are first calcined and then surface-modified with hydrochloric acid and dodecyltrimethoxysilane in sequence; 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 a molecular formula of CH3(CH2) 15The surfactant is N(Br)(CH3)3; the polyacrylamide is an anionic polyacrylamide with a molecular weight of 12 million; The preparation method is the same as in Example 1.

[0041] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that only filter aid A is used as filter aid; the formula and preparation method of filter aid A are the same as those in Example 1.

[0042] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that only filter aid B is used as filter aid; the formula and preparation method of filter aid B are the same as those in Example 1.

[0043] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that only filter aid C is used as filter aid; the formula and preparation method of filter aid C are the same as those in Example 1.

[0044] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that the filter aids only include filter aids A and filter aids B, but 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.

[0045] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that the filter aids only include filter aids A and filter aids C, but 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.

[0046] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that the filter aids only include filter aids B and filter aids C, but 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.

[0047] Comparative Example 7: The difference between Comparative Example 7 and Example 1 is that the filter aid B only uses 100-mesh hydrophobic particles, and the rest is the same as in Example 1.

[0048] Comparative Example 8: The difference between Comparative Example 8 and Example 1 is that the filter aid B only uses 200-mesh hydrophobic particles, and the rest is the same as in Example 1.

[0049] Comparative Example 9: 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 sieve of corresponding mesh number 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, they are 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 device in sequence, and mixed thoroughly at a stirring speed of 600r / min, and the stirring time is 4min, that is, filter aid B is obtained; the rest is the same as in Example 1.

[0050] Comparative Example 10: 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.

[0051] Comparative Example 11: 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.

[0052] Application examples: The filter aids in the above examples and comparative examples are applied to the dewatering of fine particle coal slime, and the specific method is as follows: 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.

[0053] 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.

[0054] Table 1: Filter aid dosage and dehydration effect.

[0055] As can be seen from Table 1, the combined filter aids of the present invention are used in Examples 1 to 6, and the moisture content of the dehydrated coal slime can reach 16.37% to 19.08%. However, in Comparative Examples 1 to 6, only one or two of filter aid A, filter aid B, and filter aid C are used, and the dehydration effect of the coal slime is reduced compared with that in Example 1. In Comparative Examples 7 and 8, filter aid B only uses hydrophobic particles of a single particle size, and the dehydration effect of the coal slime is also reduced compared with that in Example 1. In Comparative Example 9, the surface of filter aid B is not modified by dodecyltrimethoxysilane, and its surface hydrophobicity decreases, resulting in a decrease in the dehydration effect of the coal slime. In Comparative Examples 10 and 11, filter aid C only uses polyacrylamide or a surfactant, and the dehydration effect of the coal slime cannot reach the level in the examples.

Claims

1. A combined filter aid for dehydrating fine-particle coal slime, characterized in that: It includes 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 includes 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 in sequence; 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.

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 1000~14000000; 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) Preparing filter aid A: mixing polyaluminium chloride and polyaluminium sulfate in proportion and stirring evenly 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 200-mesh zeolite particles respectively, 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 into water and stir evenly to obtain filter aid C.

5. The method for preparing the 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 the combined filter aid for dehydrating fine particle coal slime according to claim 4, characterized in that: 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°C for 1-3 hours. 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 20-40 minutes, and then soaked at room temperature for 10-24 hours. After washing, it is dried at 100-110°C for 1-3 hours.

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

8. An application of a 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 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 squeezing and dehydrating the fine coal slime.

9. The use of the combined filter aid for dehydrating 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 dehydrating 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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