A composite flotation agent for coal washing and preparation method thereof

Abstract

The present invention relates to the field of chemical additives, and discloses a composite flotation agent for coal washing and a preparation method thereof. The composite flotation agent comprises the following components by weight: 60-80 parts of low-hydrogen silicone oil, 10-15 parts of kaolin composite particles, 10-15 parts of n-octanol, 5-10 parts of pine oil, and 5-10 parts of oleic acid. The specific preparation method is to first mix low-hydrogen silicone oil, n-octanol, pine oil, and oleic acid to obtain a premix, then add kaolin composite particles to the premix, stir evenly, and obtain a composite flotation agent for coal washing. The flotation agent has a high ash removal rate in coal particles, which greatly improves the quality of finished coal.

Description

Technical Field

[0001] The invention relates to the technical field of chemical additives, and in particular to a composite flotation agent for coal washing and a preparation method thereof. Background Art

[0002] my country's energy structure is characterized by rich coal, poor oil and little gas, so coal occupies a dominant position in my country's energy consumption structure. Coal is mainly used for combustion, coking, gasification, etc. The combustion-based utilization method causes serious environmental problems. At the same time, impurities such as ash and sulfur contained in coal affect the quality of coking products. The coal business supervision method clearly states that it is prohibited to sell or import high-ash, high-sulfur and low-quality coal, and it is prohibited to sell coal that does not meet the regulations to units or individuals in urban high-pollution combustion areas and no-burning areas. The implementation of the supervision method has further promoted the future development of coal washing. The purpose of coal washing is to reduce ash and desulfurize coal, and sort it into products of different particle sizes and uniform quality.

[0003] Flotation is an economical method to separate coal particles and mineral impurities based on their different surface hydrophobicity. In coal slime flotation, due to the complexity and unevenness of the coal particle surface, it is usually necessary to add flotation agents to enhance the hydrophobicity of the coal particles in order to improve the flotation effect. At present, in the prior art, flotation agents are used to flotate coal particles, and the ash content in the obtained coal particles is high, which affects the coal quality. Summary of the invention

[0004] In order to overcome the above problems of the prior art, the present invention provides a composite flotation agent for coal washing and a preparation method thereof. The flotation agent of the present invention has a high ash removal rate in coal particles, greatly improving the quality of finished coal.

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

[0006] A composite flotation agent for coal washing, comprising the following components in parts by weight:

[0007] 60-80 parts of low hydrogen silicone oil, 10-15 parts of kaolin composite particles, 10-15 parts of n-octanol, 5-10 parts of pine oil, and 5-10 parts of oleic acid.

[0008] Due to the presence of minerals in coal particles, the combustion of these minerals will produce substances that pollute the air and cause pollution to the environment, so flotation agents are needed to remove mineral impurities. Low hydrogen silicone oil belongs to non-polar hydrocarbon compounds, which are characterized by symmetrical structure, no permanent dipole, inactive chemical properties, good hydrophobicity, and when low hydrogen silicone oil contacts coal particles, since the surface of coal particles is also non-polar, low hydrogen silicone oil will adsorb, unfold and form oil film on the hydrophobic surface of coal, enhance the hydrophobicity of coal particles, and hydrophobic coal particles are easily attached to bubbles in water, with the rise of bubbles, so as to drive coal particles to float, and realize the separation of coal particles and minerals. In addition, the present invention uses kaolin composite particles to further remove the ash in coal, n-octanol and pine oil are used as composite foaming agents, and oleic acid is used as an emulsifier, and the synergistic effect between each component is utilized to realize the efficient output of clean coal and the removal of ash.

[0009] Preferably, the preparation method of the kaolin composite particles comprises the following steps:

[0010] (1) adding γ-(2,3-epoxypropoxy)propyltrimethoxysilane and γ-aminopropyltriethoxysilane to a mixed solution of ethanol and water, heating and stirring to obtain a hydrolyzate;

[0011] (2) adding kaolin particles to the hydrolyzate, heating and stirring to react, and then centrifuging, washing and drying to obtain coupling agent-modified kaolin;

[0012] (3) adding glycidyl dodecyl diethyl ammonium chloride to deionized water, stirring and dissolving to obtain an aqueous solution of glycidyl dodecyl diethyl ammonium chloride, adding coupling agent-modified kaolin to the aqueous solution of glycidyl dodecyl diethyl ammonium chloride, heating and stirring to react, centrifuging, washing and drying to obtain quaternized kaolin;

[0013] (4) adding hyperbranched polyethyleneimine into deionized water, heating and stirring to dissolve, thereby obtaining a hyperbranched polyethyleneimine solution; adding quaternized kaolin into the hyperbranched polyethyleneimine solution, heating and stirring to react; and obtaining kaolin composite particles through centrifugal separation, washing and drying.

[0014] In the technical solution of the present invention, as mentioned above, hydrophobic coal particles are easily attached to the bubbles in the water, and as the bubbles rise, the coal particles are driven to float, thereby achieving the separation of coal particles and minerals. However, in the actual coal washing process, some minerals are still mixed with the coal particles along with the bubbles, that is, a certain amount of ash still remains in the coal particles. In order to further reduce the ash content in coal particles, the present invention adds kaolin composite particles into a flotation agent. The specific preparation method of the kaolin composite particles is as follows: firstly, an aminosilane coupling agent and an epoxysilane coupling agent are grafted onto kaolin to load amino groups and epoxy groups on the surface of kaolin; then, the epoxy groups on the epoxy dodecyl diethyl ammonium chloride react with the amino groups on the kaolin to graft the epoxy dodecyl diethyl ammonium chloride onto the surface of kaolin to obtain quaternized kaolin with positive charge on the surface; then, the epoxy groups on the surface of kaolin react with the amino groups on the hyperbranched polyethyleneimine molecules to graft the hyperbranched polyethyleneimine onto the surface of kaolin to load the epoxy dodecyl diethyl ammonium chloride and the hyperbranched polyethyleneimine on the surface of kaolin at the same time. Since the mineral impurities in the coal particles are negatively charged, the negatively charged minerals are dispersed around the kaolin through the electrostatic attraction of the positively charged epoxypropyl dodecyl diethyl ammonium chloride, and then the large number of amino groups on the hyperbranched polyethyleneimine are used to form hydrogen bonds with the hydroxyl groups on the surface of the minerals, thereby combining the minerals with the kaolin. As more and more minerals are combined with the kaolin, they sink under the action of gravity, thereby further separating the coal particles from the minerals, reducing the ash content in the coal particles, and improving the purity and quality of the coal particles.

[0015] Preferably, in step (1), the mass ratio of γ-(2,3-epoxypropyloxy)propyltrimethoxysilane to γ-aminopropyltriethoxysilane is 1:1-3.

[0016] Preferably, in step (2), the heating temperature is 50-60° C. and the stirring reaction time is 2-3 h.

[0017] Preferably, in step (3), the mass ratio of coupling agent-modified kaolin to glycidyl dodecyl diethyl ammonium chloride is 1:0.2-1.5.

[0018] Preferably, in step (3), the heating temperature is 70-80° C. and the stirring reaction time is 2-3 h.

[0019] Preferably, in step (4), the mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:0.5-0.9.

[0020] In the technical solution of the present invention, as described above, a large number of amino groups on hyperbranched polyethyleneimine are used to form hydrogen bonding forces with hydroxyl groups on the surface of minerals, thereby combining the minerals with kaolin. As more and more minerals are combined on kaolin, they sink under the action of gravity, thereby further separating the coal particles from the minerals and reducing the ash content in the coal particles. The present invention has found through experiments that a sufficient amount of hyperbranched polyethyleneimine must be grafted on the surface of kaolin to form a strong hydrogen bonding force with the surface of the minerals, thereby reducing the ash content in the coal particles. Therefore, the present invention controls the mass ratio of quaternized kaolin to hyperbranched polyethyleneimine to be less than 1:0.5.

[0021] However, the present invention team unexpectedly discovered through research that when the mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is less than 1:0.9, the yield of clean coal will drop significantly, which was unexpected by the present invention team. This may be because too much hyperbranched polyethyleneimine is grafted on the surface of the quaternized kaolin, and the excess amino groups form hydrogen bonding forces with a small part of oxygen-containing functional groups such as hydroxyl and carboxyl on the coal particles, thereby preventing the coal particles from floating, resulting in a decrease in the yield of clean particles. Therefore, in order to simultaneously ensure the yield of clean coal, the present invention controls the mass ratio of quaternized kaolin to hyperbranched polyethyleneimine to be greater than 1:0.9.

[0022] Preferably, in step (4), the heating temperature is 80-85° C. and the stirring reaction time is 3-5 h.

[0023] A method for preparing a composite flotation agent for coal washing comprises the following steps:

[0024] Mix low hydrogen silicone oil, octanol, pine oil and oleic acid, and stir at 800-900 r / min for 20-50 min to obtain a premix;

[0025] Add kaolin composite particles into the premix, stir at 1000-1500 r / min for 30-60 min, and obtain a composite flotation agent for coal washing.

[0026] The present invention has the following beneficial effects:

[0027] (1) Low-hydrogen silicone oil will adsorb, spread and form an oil film on the hydrophobic surface of coal, enhancing the hydrophobicity of coal particles. Hydrophobic coal particles are easy to adhere to bubbles in the water. As the bubbles rise, the coal particles will float up, thus achieving the separation of coal particles and minerals;

[0028] (2) Mineral impurities in coal particles are negatively charged. The negatively charged minerals are dispersed around kaolin through the electrostatic attraction of positively charged epoxypropyl dodecyl diethyl ammonium chloride. Then, a large number of amino groups on hyperbranched polyethyleneimine are used to form hydrogen bonds with the hydroxyl groups on the surface of the minerals, thereby combining the minerals with kaolin. As more and more minerals are combined with kaolin, they sink under the action of gravity, thereby further separating the coal particles from the minerals, reducing the ash content in the coal particles, and improving the purity and quality of the coal particles.

[0029] (3) The present invention achieves the goal of reducing the ash content in coal while ensuring the clean coal yield by reasonably controlling the mass ratio of quaternized kaolin and hyperbranched polyethyleneimine. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0031] Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art.

[0032] The low hydrogen silicone oil used in the specific embodiment has a viscosity of 80 mPa·s and a hydrogen content of 0.1-0.2%.

[0033] Embodiment 1: A composite flotation agent for coal washing, comprising the following components in parts by weight:

[0034] 78 parts of low hydrogen silicone oil, 14 parts of kaolin composite particles, 13 parts of n-octanol, 9 parts of pine oil, and 9 parts of oleic acid.

[0035] The preparation method of kaolin composite particles comprises the following steps:

[0036] (1) Add 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 2.5 g of γ-aminopropyltriethoxysilane to a mixed solution of 80 mL of ethanol and 10 mL of water, heat to 50 °C and stir for 20 min to obtain a hydrolyzate;

[0037] (2) Add 5 g of kaolin particles to the hydrolyzate, heat and stir at 55 °C for 2.5 h, and obtain coupling agent-modified kaolin after centrifugal separation, washing and drying;

[0038] (3) Add 3 g of glycidyl dodecyl diethyl ammonium chloride to 150 mL of deionized water, stir and dissolve to obtain an aqueous solution of glycidyl dodecyl diethyl ammonium chloride, add coupling agent-modified kaolin to the aqueous solution of glycidyl dodecyl diethyl ammonium chloride, the mass ratio of coupling agent-modified kaolin to glycidyl dodecyl diethyl ammonium chloride being 1:1.3, heat and stir at 75°C to react for 2.5 h, centrifuge, wash and dry to obtain quaternized kaolin;

[0039] (4) Add 2.5 g of hyperbranched polyethyleneimine to 150 mL of deionized water, heat to 50 °C and stir to dissolve, to obtain a hyperbranched polyethyleneimine solution, add quaternized kaolin to the hyperbranched polyethyleneimine solution, the mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:0.8, heat to 83 °C and stir to react for 4 h, and obtain kaolin composite particles after centrifugal separation, washing and drying.

[0040] A method for preparing a composite flotation agent for coal washing comprises the following steps:

[0041] Mix low hydrogen silicone oil, octanol, pinol oil and oleic acid, and stir at 850 r / min for 30 min to obtain a premix;

[0042] Kaolin composite particles were added to the premix, and the mixture was stirred at 1200 r / min for 50 min to obtain a composite flotation agent for coal washing.

[0043] Embodiment 2: A composite flotation agent for coal washing, comprising the following components in parts by weight:

[0044] 63 parts of low hydrogen silicone oil, 12 parts of kaolin composite particles, 11 parts of n-octanol, 6 parts of pine oil, and 7 parts of oleic acid.

[0045] The preparation method of kaolin composite particles comprises the following steps:

[0046] (1) Add 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 1.5 g of γ-aminopropyltriethoxysilane to a mixed solution of 80 mL of ethanol and 10 mL of water, heat to 50 °C and stir for 20 min to obtain a hydrolyzate;

[0047] (2) Add 5 g of kaolin particles to the hydrolyzate, heat and stir at 55 °C for 2.5 h, and obtain coupling agent-modified kaolin after centrifugal separation, washing and drying;

[0048] (3) Add 3 g of glycidyl dodecyl diethyl ammonium chloride to 150 mL of deionized water, stir and dissolve to obtain an aqueous solution of glycidyl dodecyl diethyl ammonium chloride, add coupling agent-modified kaolin to the aqueous solution of glycidyl dodecyl diethyl ammonium chloride, the mass ratio of coupling agent-modified kaolin to glycidyl dodecyl diethyl ammonium chloride is 1:0.5, heat and stir at 75°C to react for 2.5 h, centrifuge, wash and dry to obtain quaternized kaolin;

[0049] (4) Add 2.5 g of hyperbranched polyethyleneimine to 150 mL of deionized water, heat to 50 °C and stir to dissolve, to obtain a hyperbranched polyethyleneimine solution, add quaternized kaolin to the hyperbranched polyethyleneimine solution, the mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:0.6, heat to 83 °C and stir to react for 4 h, and obtain kaolin composite particles after centrifugal separation, washing and drying.

[0050] A method for preparing a composite flotation agent for coal washing comprises the following steps:

[0051] Mix low hydrogen silicone oil, n-octanol, pine oil and oleic acid, and stir at 850 r / min for 30 min to obtain a premix;

[0052] Kaolin composite particles were added to the premix, and the mixture was stirred at 1200 r / min for 50 min to obtain a composite flotation agent for coal washing.

[0053] Embodiment 3: A composite flotation agent for coal washing, comprising the following components in parts by weight:

[0054] 70 parts of low hydrogen silicone oil, 13 parts of kaolin composite particles, 12 parts of n-octanol, 8 parts of pine oil, and 8 parts of oleic acid.

[0055] The preparation method of kaolin composite particles comprises the following steps:

[0056] (1) Add 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 2 g of γ-aminopropyltriethoxysilane to a mixed solution of 80 mL of ethanol and 10 mL of water, heat to 50 °C and stir for 20 min to obtain a hydrolyzate;

[0057] (2) Add 5 g of kaolin particles to the hydrolyzate, heat and stir at 55 °C for 2.5 h, and obtain coupling agent-modified kaolin after centrifugal separation, washing and drying;

[0058] (3) Add 3 g of glycidyl dodecyl diethyl ammonium chloride to 150 mL of deionized water and stir to dissolve to obtain an aqueous solution of glycidyl dodecyl diethyl ammonium chloride. Add coupling agent-modified kaolin to the aqueous solution of glycidyl dodecyl diethyl ammonium chloride. The mass ratio of coupling agent-modified kaolin to glycidyl dodecyl diethyl ammonium chloride is 1:0.8. Heat and stir at 75°C to react for 2.5 h. After centrifugation, washing and drying, quaternized kaolin is obtained.

[0059] (4) Add 2.5 g of hyperbranched polyethyleneimine to 150 mL of deionized water, heat to 50 °C and stir to dissolve, to obtain a hyperbranched polyethyleneimine solution, add quaternized kaolin to the hyperbranched polyethyleneimine solution, the mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:0.7, heat to 83 °C and stir to react for 4 h, and obtain kaolin composite particles after centrifugal separation, washing and drying.

[0060] A method for preparing a composite flotation agent for coal washing comprises the following steps:

[0061] Mix low hydrogen silicone oil, n-octanol, pine oil and oleic acid, and stir at 850 r / min for 30 min to obtain a premix;

[0062] Kaolin composite particles were added to the premix, and the mixture was stirred at 1200 r / min for 50 min to obtain a composite flotation agent for coal washing.

[0063] Embodiment 4: A composite flotation agent for coal washing, comprising the following components in parts by weight:

[0064] 80 parts of low hydrogen silicone oil, 15 parts of kaolin composite particles, 15 parts of n-octanol, 10 parts of pine oil, and 10 parts of oleic acid.

[0065] The preparation method of kaolin composite particles comprises the following steps:

[0066] (1) Add 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 3 g of γ-aminopropyltriethoxysilane to a mixed solution of 80 mL of ethanol and 10 mL of water, heat to 50 °C and stir for 20 min to obtain a hydrolyzate;

[0067] (2) Add 5 g of kaolin particles to the hydrolyzate, heat and stir at 60 °C for 3 h, and obtain coupling agent-modified kaolin after centrifugal separation, washing and drying;

[0068] (3) Add 3 g of glycidyl dodecyl diethyl ammonium chloride to 150 mL of deionized water, stir and dissolve to obtain an aqueous solution of glycidyl dodecyl diethyl ammonium chloride, add coupling agent-modified kaolin to the aqueous solution of glycidyl dodecyl diethyl ammonium chloride, the mass ratio of coupling agent-modified kaolin to glycidyl dodecyl diethyl ammonium chloride being 1:1.5, heat and stir at 80°C to react for 3 h, centrifuge, wash and dry to obtain quaternized kaolin;

[0069] (4) Add 2.5 g of hyperbranched polyethyleneimine to 150 mL of deionized water, heat to 50 °C and stir to dissolve, to obtain a hyperbranched polyethyleneimine solution, add quaternized kaolin to the hyperbranched polyethyleneimine solution, the mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:0.9, heat to 85 °C and stir to react for 5 h, and obtain kaolin composite particles after centrifugal separation, washing and drying.

[0070] A method for preparing a composite flotation agent for coal washing comprises the following steps:

[0071] Mix low hydrogen silicone oil, n-octanol, pine oil and oleic acid, and stir at 900 r / min for 50 min to obtain a premix;

[0072] Kaolin composite particles were added to the premix, and the mixture was stirred at 1500 r / min for 60 min to obtain a composite flotation agent for coal washing.

[0073] Example 5: A composite flotation agent for coal washing, comprising the following components in parts by weight:

[0074] 60 parts of low hydrogen silicone oil, 10 parts of kaolin composite particles, 10 parts of n-octanol, 5 parts of pine oil, and 5 parts of oleic acid.

[0075] The preparation method of kaolin composite particles comprises the following steps:

[0076] (1) Add 1 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 1 g of γ-aminopropyltriethoxysilane to a mixed solution of 80 mL of ethanol and 10 mL of water, heat to 50 °C and stir for 20 min to obtain a hydrolyzate;

[0077] (2) Add 5 g of kaolin particles to the hydrolyzate, heat and stir at 50 °C for 2 h, and obtain coupling agent-modified kaolin after centrifugal separation, washing and drying;

[0078] (3) Add 3 g of glycidyl dodecyl diethyl ammonium chloride to 150 mL of deionized water and stir to dissolve to obtain an aqueous solution of glycidyl dodecyl diethyl ammonium chloride. Add coupling agent-modified kaolin to the aqueous solution of glycidyl dodecyl diethyl ammonium chloride. The mass ratio of coupling agent-modified kaolin to glycidyl dodecyl diethyl ammonium chloride is 1:0.2. Heat and stir at 70°C to react for 2 h. After centrifugation, washing and drying, quaternized kaolin is obtained.

[0079] (4) Add 2.5 g of hyperbranched polyethyleneimine to 150 mL of deionized water, heat to 50 °C and stir to dissolve, to obtain a hyperbranched polyethyleneimine solution, add quaternized kaolin to the hyperbranched polyethyleneimine solution, the mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:0.5, heat to 80 °C and stir to react for 3 h, and obtain kaolin composite particles after centrifugal separation, washing and drying.

[0080] A method for preparing a composite flotation agent for coal washing comprises the following steps:

[0081] Mix low hydrogen silicone oil, n-octanol, pine oil and oleic acid, and stir at 800 r / min for 20 min to obtain a premix;

[0082] Kaolin composite particles were added to the premix, and the mixture was stirred at 1000 r / min for 30 min to obtain a composite flotation agent for coal washing.

[0083] Comparative Example 1

[0084] The difference between Comparative Example 1 and Example 1 is:

[0085] No kaolin composite particles are added to the flotation agent.

[0086] The remaining steps are the same as those in Example 1.

[0087] Comparative Example 2

[0088] The difference between Comparative Example 2 and Example 1 is:

[0089] The kaolin composite particles were replaced with ordinary kaolin particles.

[0090] The remaining steps are the same as those in Example 1.

[0091] Comparative Example 3

[0092] The difference between Comparative Example 3 and Example 5 is that:

[0093] During the preparation of kaolin composite particles,

[0094] The mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:0.4.

[0095] The remaining steps are the same as those in Example 5.

[0096] Comparative Example 4

[0097] The difference between Comparative Example 4 and Example 4 is that:

[0098] During the preparation of kaolin composite particles,

[0099] The mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:1.

[0100] The remaining steps are the same as those in Example 4.

[0101] Comparative Example 5

[0102] The difference between Comparative Example 5 and Example 4 is that:

[0103] During the preparation of kaolin composite particles,

[0104] The mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:1.1.

[0105] The remaining steps are the same as those in Example 4.

[0106] Comparative Example 6

[0107] The difference between Comparative Example 6 and Example 4 is that:

[0108] During the preparation of kaolin composite particles,

[0109] The mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:1.2.

[0110] The remaining steps are the same as those in Example 4.

[0111] Comparative Example 7

[0112] The difference between Comparative Example 7 and Example 4 is that:

[0113] During the preparation of kaolin composite particles,

[0114] The mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:1.5.

[0115] The remaining steps are the same as those in Example 4.

[0116] Performance Testing

[0117] Take the raw coal sample particles and add water to prepare a slurry with a concentration of 100g / L, then add the flotation agent (dosage 0.1kg / t) in the embodiment and the comparative example respectively, stir for 20min, then scrape and collect the foam, dehydrate the foam, and then dry to obtain clean coal. The yield and ash content of the coal are tested according to the method of GB / T 212-2008 "Industrial Analysis Method of Coal", and the test results are as follows:

[0118] Ash content (%) Clean coal yield (%) Example 1 2.53 87.34 Example 2 3.17 86.21 Example 3 2.82 86.73 Example 4 2.36 89.67 Example 5 3.52 86.12 Comparative Example 1 11.53 83.25 Comparative Example 2 11.67 83.17 Comparative Example 3 8.16 83.69 Comparative Example 4 2.36 78.23 Comparative Example 5 2.35 77.51 Comparative Example 6 2.35 77.06 Comparative Example 7 2.31 75.25

[0119] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A composite flotation agent for coal washing, characterized in that: It comprises the following components by weight: 60-80 parts of low hydrogen silicone oil, 10-15 parts of kaolin composite particles, 10-15 parts of n-octanol, 5-10 parts of pine oil, and 5-10 parts of oleic acid; The preparation method of the kaolin composite particles comprises the following steps: (1) adding γ-(2,3-epoxypropoxy)propyltrimethoxysilane and γ-aminopropyltriethoxysilane to a mixed solution of ethanol and water, heating and stirring to obtain a hydrolyzate; (2) adding kaolin particles to the hydrolyzate, heating and stirring to react, and then centrifuging, washing and drying to obtain coupling agent-modified kaolin; (3) adding glycidyl dodecyl diethyl ammonium chloride to deionized water, stirring to dissolve, and obtaining an aqueous solution of glycidyl dodecyl diethyl ammonium chloride; adding coupling agent-modified kaolin to the aqueous solution of glycidyl dodecyl diethyl ammonium chloride, heating and stirring to react; and centrifuging, washing and drying to obtain quaternized kaolin; (4) adding hyperbranched polyethyleneimine into deionized water, heating and stirring to dissolve, thereby obtaining a hyperbranched polyethyleneimine solution; adding quaternized kaolin into the hyperbranched polyethyleneimine solution, heating and stirring to react; and obtaining kaolin composite particles through centrifugal separation, washing and drying.

2. A composite flotation agent for coal washing according to claim 1, characterized in that: In the step (1), the mass ratio of γ-(2,3-epoxypropoxy)propyltrimethoxysilane to γ-aminopropyltriethoxysilane is 1:1-3.

3. A composite flotation agent for coal washing according to claim 1, characterized in that: In the step (2), the heating temperature is 50-60° C. and the stirring reaction time is 2-3 h.

4. A composite flotation agent for coal washing according to claim 1, characterized in that: In the step (3), the mass ratio of the coupling agent-modified kaolin to the epoxypropyl dodecyl diethyl ammonium chloride is 1:0.2-1.

5.

5. A composite flotation agent for coal washing according to claim 1, characterized in that: In the step (3), the heating temperature is 70-80° C. and the stirring reaction time is 2-3 h.

6. A composite flotation agent for coal washing according to claim 1, characterized in that: In the step (4), the mass ratio of quaternized kaolin to hyperbranched polyethyleneimine is 1:0.5-0.

9.

7. A composite flotation agent for coal washing according to claim 1, characterized in that: In the step (4), the heating temperature is 80-85°C and the stirring reaction time is 3-5h.

8. A method for preparing a composite flotation agent for coal washing according to any one of claims 1 to 7, characterized in that: The following steps are involved: Mix low hydrogen silicone oil, n-octanol, pine oil and oleic acid, and stir at 800-900 r / min for 20-50 min to obtain a premix; Add kaolin composite particles into the premix, stir at 1000-1500 r / min for 30-60 min, and obtain a composite flotation agent for coal washing.