A coal flotation agent and its preparation method

Abstract

The present invention relates to the technical field of chemical additives, and discloses a coal flotation agent and a preparation method thereof. The specific method is to mix oily sludge, cyclohexanol, methyl pentanol, sodium dodecyl sulfate and water, and stir to obtain a premix; add chitosan composite microspheres to the premix and continue to stir to obtain the coal flotation agent. The present invention has a high removal rate of minerals in coal, reduces the ash generated by carbon burning, and improves the quality of coal.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical additives, and particularly to a coal flotation agent and a preparation method thereof. Background Art

[0002] The energy structure in China is characterized by rich coal, poor oil, and little gas. Therefore, coal occupies a dominant position in China's energy consumption structure. Coal is mainly used in combustion, coking, gasification, etc. The utilization method mainly based on combustion causes serious environmental problems. At the same time, impurities such as ash and sulfur contained in coal affect the quality of coking products. The purpose of coal washing is to reduce ash and desulfurize coal, and separate it into products with different particle sizes and uniform quality. Flotation is an economical method for separation based on the different surface hydrophobicities of coal particles and mineral impurities. In coal flotation, due to the complexity and non-uniformity of the surface of coal particles, it is usually necessary to add flotation agents to enhance the hydrophobicity of coal particles in order to improve the flotation effect. That is, the oily substances in the flotation agent will adsorb, spread and form an oil film on the hydrophobic surface of coal, enhancing the hydrophobicity of coal particles. The hydrophobic coal particles are easily attached to the bubbles in water and rise with the bubbles, thereby driving the coal particles to float and realizing the separation of coal particles from minerals. However, in the actual separation process, some minerals will also be wrapped by oily substances and float up with the bubbles, resulting in some ash in the coal and affecting the quality of coal. Summary of the Invention

[0003] In order to overcome the above prior art problems, the present invention provides a coal flotation agent and a preparation method thereof. The present invention has a high removal rate of minerals in coal, reduces the ash generated by combustion, and improves the quality of coal.

[0004] In order to achieve the above invention purposes, the present invention adopts the following technical solutions:

[0005] A coal flotation agent, comprising the following components by weight:

[0006] 80 - 100 parts of oily sludge, 10 - 20 parts of chitosan composite microspheres, 10 - 15 parts of cyclohexanol, 5 - 10 parts of methylpentanol, 5 - 10 parts of sodium dodecyl sulfate, and 150 - 180 parts of water.

[0007] The coal flotation agent of the present invention uses oily sludge as the oily component, a mixture of cyclohexane and methyl amyl alcohol as the mixed foaming agent, and sodium dodecyl sulfate as the emulsifier. In the prior art, the oily component in the flotation agent is used to wrap the coal particles to improve the hydrophobic property of their surfaces. The hydrophobic coal particles are easily attached to the surface of the bubbles in water, so that the coal particles float on the water surface, realizing the separation of coal particles from impurities. However, in the actual flotation process, part of the oily component in the flotation agent will also partially wrap on the surface of mineral particles, resulting in some minerals being doped in the coal, affecting the quality of the coal. In order to reduce the minerals in the coal and improve the purity of the coal, the present invention adds chitosan composite microsphere particles to the flotation agent. The chitosan composite microsphere surface is loaded with a large number of amino groups and hydroxyl groups, having good hydrophilic properties, and the hydroxyl and amino groups on its surface form hydrogen bond forces with the hydroxyl groups on the mineral surface, so that the chitosan composite microsphere binds to the surface of the mineral particles, thus greatly improving the hydrophilic property of the mineral particle surface. Since the mineral surface has extremely strong hydrophilicity, there is a strong repulsive force between its surface and the oily component in the flotation agent, making it difficult for the oily substances in the flotation machine to wrap on the surface of the mineral particles, thereby realizing the complete separation of coal particles from minerals, significantly improving the purity of the coal particles after flotation, reducing the ash content in the coal, and further improving the quality of the coal.

[0008] Preferably, the preparation method of the chitosan composite microsphere comprises the following steps:

[0009] 1) Dissolve chitosan in acetic acid solution to prepare a chitosan solution, dissolve sodium alginate in water to prepare a sodium alginate solution, mix the chitosan solution and the sodium alginate solution to obtain a mixed solution A, and set aside;

[0010] 2) Mix liquid paraffin and span-80 to obtain a mixed solution B, slowly drop the above mixed solution A into the mixed solution B for emulsification to obtain an emulsion;

[0011] 3) Add a glutaraldehyde crosslinking agent to the emulsion for crosslinking reaction, and after centrifugal separation, washing and drying, obtain the chitosan composite microsphere.

[0012] In the technical solution of the present invention, since waste oily sludge is used as the oily component of the flotation agent, but a further problem encountered is that the oily sludge contains heavy metals, and its doping into coal combustion will cause further environmental pollution. In order to further solve this technical problem, the present invention prepares chitosan composite microspheres through chitosan and sodium alginate, so that the chitosan composite microspheres are loaded with carboxyl groups, and the carboxyl groups can form a complexation effect with heavy metals, so that the heavy metals bind to the chitosan composite microspheres. The chitosan composite microspheres further bind to the mineral particles in the coal, so that while the coal particles are separated from the mineral particles, they are separated from the heavy metals in the oily sludge, further improving the quality of the coal particles.

[0013] Preferably, in the step 1), the concentration of the chitosan solution is 0.2 - 3 wt%.

[0014] Preferably, in the step 1), the concentration of the sodium alginate solution is 1 - 5 wt%.

[0015] Preferably, in the step 1), the mass ratio of chitosan to sodium alginate is 1:0.8 - 1.3.

[0016] In the technical solution of the present invention, as described above, chitosan composite microspheres are prepared from chitosan and sodium alginate, so that carboxyl groups are loaded in the chitosan composite microspheres. The carboxyl groups can form a complexing action with heavy metals, thereby achieving the purpose of removing heavy metals. In order for the chitosan composite microspheres to form a complexing force with heavy metals, the chitosan composite microspheres must be loaded with a sufficient amount of carboxyl groups. Therefore, the present invention controls the mass ratio of chitosan to sodium alginate to be less than 1:0.8. However, when the mass ratio of chitosan to sodium alginate is less than 1:1.3, the present invention team unexpectedly found that the mineral content in the flotation coal increased significantly, that is, the ash content after combustion increased significantly. This was not expected by the present invention team. This may be because as the amount of sodium alginate increases, an excessive amount of carboxyl groups are loaded on the chitosan composite microspheres, making the chitosan composite microspheres strongly negatively charged. It forms a strong repulsive force with the negatively charged minerals, preventing the chitosan composite microspheres from binding to the mineral particles, and thus leading to an increase in the mineral content in the coal and an increase in the ash content after coal combustion. Therefore, the present invention also strictly controls the mass ratio of chitosan to sodium alginate to be greater than 1:1.3.

[0017] Preferably, in the step 2), the volume ratio of the mixed solution A to the mixed solution B is 1:10 - 20.

[0018] Preferably, in the step 2), the addition amount of glutaraldehyde is 0.5 - 1.0% of the mass of chitosan.

[0019] A preparation method of a coal flotation agent, comprising the following steps:

[0020] Mix oily sludge, cyclohexanol, methyl pentanol, sodium dodecyl sulfate and water, and stir at 600 - 800 r / min for 30 - 60 min to obtain a premix;

[0021] Add chitosan composite microspheres to the premix, and stir at 1000 - 1300 r / min for 20 - 30 min to obtain a coal flotation agent.

[0022] The present invention has the following beneficial effects:

[0023] Adding chitosan composite microsphere particles to the flotation agent, a large number of amino groups and hydroxyl groups are loaded on the surface of the chitosan composite microspheres, which have good hydrophilic properties. Moreover, the hydroxyl and amino groups on their surface form hydrogen bond forces with the hydroxyl groups on the surface of minerals, so that the chitosan composite microspheres are combined on the surface of mineral particles, thus greatly improving the hydrophilic properties of the surface of mineral particles. Due to the extremely strong hydrophilicity of the mineral surface, there is a strong repulsive force between its surface and the oily components in the flotation agent, making it difficult for the oily substances in the flotation machine to wrap around the surface of mineral particles, thereby realizing the complete separation of coal particles and minerals, significantly improving the purity of coal particles after flotation, reducing the ash content in coal, and further improving the quality of coal;

[0024] 2) Preparing chitosan composite microspheres from chitosan and sodium alginate, so that carboxyl groups are loaded in the chitosan composite microspheres. The carboxyl groups can form a complexation reaction with heavy metals, so that the heavy metals are combined on the chitosan composite microspheres. The chitosan composite microspheres are further combined with the mineral particles in coal, so that while the coal particles are separated from the mineral particles, they are separated from the heavy metals in the oily sludge, further improving the quality of coal particles. Specific embodiments

[0025] The following further clearly and detailedly describes the present invention in combination 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 descriptions are usually only a part of the embodiments of the present invention, rather than all the embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the scope of protection of the present invention.

[0026] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available or raw materials that can be obtained by those skilled in the art; unless otherwise specified, the methods used in the embodiments of the present invention are all methods mastered by those skilled in the art.

[0027] The oily sludge used in the specific embodiments of the present invention is the oily sludge formed during the oil extraction process.

[0028] Example 1: Preparation of chitosan composite microspheres:

[0029] 1) Dissolve chitosan in an acetic acid solution with a volume fraction of 2% to prepare a chitosan solution with a mass concentration of 2 wt%, and dissolve sodium alginate in water to prepare a sodium alginate solution with a mass concentration of 4 wt%;

[0030] Mix the chitosan solution and the sodium alginate solution, and the mass ratio of chitosan to sodium alginate is 1:1.2 to obtain a mixed solution A for standby;

[0031] 2) Mix liquid paraffin and span-80 in a volume ratio of 50:2 to obtain mixture B. Slowly add the above mixture A to mixture B, with the volume ratio of mixture A to mixture B being 1:18. Heat to 60 °C and stir for emulsification for 50 min to obtain an emulsion;

[0032] 3) Add glutaraldehyde cross-linking agent to the emulsion. The addition amount of glutaraldehyde is 0.9% of the mass of chitosan. Carry out cross-linking reaction for 3 h, and obtain chitosan composite microspheres after centrifugal separation, washing and drying.

[0033] A coal flotation agent comprises the following components by weight:

[0034] 95 parts of oily sludge, 18 parts of chitosan composite microspheres, 13 parts of cyclohexanol, 8 parts of methyl pentanol, 9 parts of sodium dodecyl sulfate, and 170 parts of water.

[0035] A preparation method of a coal flotation agent comprises the following steps:

[0036] Mix oily sludge, cyclohexanol, methyl pentanol, sodium dodecyl sulfate and water, and stir at 700 r / min for 50 min to obtain a premix;

[0037] Add chitosan composite microspheres to the premix, and stir at 1200 r / min for 25 min to obtain a coal flotation agent.

[0038] Example 2: Preparation of chitosan composite microspheres:

[0039] 1) Dissolve chitosan in an acetic acid solution with a volume fraction of 2% to prepare a chitosan solution with a mass concentration of 0.8 wt%. Dissolve sodium alginate in water to prepare a sodium alginate solution with a mass concentration of 2 wt%;

[0040] Mix the chitosan solution and the sodium alginate solution, with the mass ratio of chitosan to sodium alginate being 1:0.9, to obtain mixture A for standby;

[0041] 2) Mix liquid paraffin and span-80 in a volume ratio of 50:2 to obtain mixture B. Slowly add the above mixture A to mixture B, with the volume ratio of mixture A to mixture B being 1:12. Heat to 60 °C and stir for emulsification for 50 min to obtain an emulsion;

[0042] 3) Add glutaraldehyde cross-linking agent to the emulsion. The addition amount of glutaraldehyde is 0.6% of the mass of chitosan. Carry out cross-linking reaction for 3 h, and obtain chitosan composite microspheres after centrifugal separation, washing and drying.

[0043] A coal flotation agent comprises the following components by weight:

[0044] 85 parts of oily sludge, 12 parts of chitosan composite microspheres, 10 parts of cyclohexanol, 6 parts of methylpentanol, 7 parts of sodium dodecyl sulfate, 160 parts of water.

[0045] A preparation method of a coal flotation agent, comprising the following steps:

[0046] Mix oily sludge, cyclohexanol, methylpentanol, sodium dodecyl sulfate and water, stir at 700 r / min for 40 min to obtain a premix;

[0047] Add chitosan composite microspheres to the premix, stir at 1200 r / min for 25 min to obtain a coal flotation agent.

[0048] Example 3: Preparation of chitosan composite microspheres:

[0049] 1) Dissolve chitosan in an acetic acid solution with a volume fraction of 2% to prepare a chitosan solution with a mass concentration of 1 wt%, and dissolve sodium alginate in water to prepare a sodium alginate solution with a mass concentration of 3 wt%;

[0050] Mix the chitosan solution and the sodium alginate solution, and the mass ratio of chitosan to sodium alginate is 1:1 to obtain a mixed solution A for standby;

[0051] 2) Mix liquid paraffin and span-80 according to a volume ratio of 50:2 to obtain a mixed solution B, slowly drop the above mixed solution A into the mixed solution B, and the volume ratio of the mixed solution A to the mixed solution B is 1:15, heat to 60 °C, stir and emulsify for 50 min to obtain an emulsion;

[0052] 3) Add glutaraldehyde cross-linking agent to the emulsion, the addition amount of glutaraldehyde is 0.8% of the mass of chitosan, carry out cross-linking reaction for 3 h, and obtain chitosan composite microspheres through centrifugal separation, washing and drying.

[0053] A coal flotation agent, comprising the following components by weight:

[0054] 90 parts of oily sludge, 15 parts of chitosan composite microspheres, 12 parts of cyclohexanol, 7 parts of methylpentanol, 8 parts of sodium dodecyl sulfate, 170 parts of water.

[0055] A preparation method of a coal flotation agent, comprising the following steps:

[0056] Mix oily sludge, cyclohexanol, methylpentanol, sodium dodecyl sulfate and water, stir at 700 r / min for 40 min to obtain a premix;

[0057] Add chitosan composite microspheres to the premix, stir at 1200 r / min for 25 min to obtain a coal flotation agent.

[0058] Example 4: Preparation of chitosan composite microspheres:

[0059] 1) Dissolve chitosan in acetic acid solution with a volume fraction of 2% to prepare a chitosan solution with a mass concentration of 3 wt%, and dissolve sodium alginate in water to prepare a sodium alginate solution with a mass concentration of 5 wt%;

[0060] Mix the chitosan solution and the sodium alginate solution, with the mass ratio of chitosan to sodium alginate being 1:1.3, to obtain a mixed solution A for standby;

[0061] 2) Mix liquid paraffin and span-80 according to a volume ratio of 50:2 to obtain a mixed solution B, slowly drop the above mixed solution A into the mixed solution B, with the volume ratio of the mixed solution A to the mixed solution B being 1:20, heat to 60 °C, and stir and emulsify for 50 min to obtain an emulsion;

[0062] 3) Add glutaraldehyde cross-linking agent to the emulsion, with the addition amount of glutaraldehyde being 1.0% of the mass of chitosan, carry out cross-linking reaction for 3 h, and obtain chitosan composite microspheres through centrifugal separation, washing and drying.

[0063] A coal flotation agent, comprising the following components by weight:

[0064] 100 parts of oily sludge, 20 parts of chitosan composite microspheres, 15 parts of cyclohexanol, 10 parts of methyl pentanol, 10 parts of sodium dodecyl sulfate, and 180 parts of water.

[0065] A preparation method of a coal flotation agent, comprising the following steps:

[0066] Mix oily sludge, cyclohexanol, methyl pentanol, sodium dodecyl sulfate and water, and stir at 800 r / min for 30 min to obtain a premix;

[0067] Add chitosan composite microspheres to the premix, and stir at 1300 r / min for 20 min to obtain a coal flotation agent.

[0068] Example 5: Preparation of chitosan composite microspheres:

[0069] 1) Dissolve chitosan in acetic acid solution with a volume fraction of 2% to prepare a chitosan solution with a mass concentration of 0.2 wt%, and dissolve sodium alginate in water to prepare a sodium alginate solution with a mass concentration of 1 wt%;

[0070] Mix the chitosan solution and the sodium alginate solution, with the mass ratio of chitosan to sodium alginate being 1:0.8, to obtain a mixed solution A for standby;

[0071] 2) Mix liquid paraffin and span-80 in a volume ratio of 50:2 to obtain mixture B. Slowly drop the above mixture A into mixture B, with the volume ratio of mixture A to mixture B being 1:10. Heat to 60 °C and stir for emulsification for 50 min to obtain an emulsion;

[0072] 3) Add glutaraldehyde cross-linking agent to the emulsion. The addition amount of glutaraldehyde is 0.5% of the mass of chitosan, and carry out cross-linking reaction for 3 h. After centrifugal separation, washing and drying, chitosan composite microspheres are obtained.

[0073] A coal flotation agent comprises the following components by weight:

[0074] 80 parts of oily sludge, 10 parts of chitosan composite microspheres, 10 parts of cyclohexanol, 5 parts of methyl pentanol, 5 parts of sodium dodecyl sulfate, and 150 parts of water.

[0075] A preparation method of a coal flotation agent comprises the following steps:

[0076] Mix oily sludge, cyclohexanol, methyl pentanol, sodium dodecyl sulfate and water, and stir at 600 r / min for 60 min to obtain a premix;

[0077] Add chitosan composite microspheres to the premix and stir at 1000 r / min for 30 min to obtain a coal flotation agent.

[0078] Comparative Example 1

[0079] The difference between Comparative Example 1 and Example 1 is that:

[0080] The coal flotation agent does not contain chitosan composite microspheres;

[0081] Its operation steps are the same as those of Example 1.

[0082] Comparative Example 2

[0083] The difference between Comparative Example 2 and Example 4 is that:

[0084] The mass ratio of chitosan to sodium alginate is 1:1.4;

[0085] Its operation steps are the same as those of Example 4.

[0086] Comparative Example 3

[0087] The difference between Comparative Example 3 and Example 4 is that:

[0088] The mass ratio of chitosan to sodium alginate is 1:1.5;

[0089] Its operation steps are the same as those of Example 4.

[0090] Comparative Example 4

[0091] The difference between Comparative Example 4 and Example 4 is that:

[0092] The mass ratio of chitosan to sodium alginate is 1:1.6;

[0093] Its operation steps are the same as those of Example 4.

[0094] Comparative Example 5

[0095] The difference between Comparative Example 5 and Example 4 is that:

[0096] The mass ratio of chitosan to sodium alginate is 1:1.7;

[0097] Its operation steps are the same as those of Example 4.

[0098] Performance Test

[0099] Take raw coal particles and add water to prepare a pulp with a concentration of 100 g / L, then add the flotation agents in the examples and comparative examples respectively (dosage 0.1 kg / t), stir for 20 min, then carry out skimming and collect the foam, dehydrate the foam, and then dry it to obtain clean coal. According to the method of GB / T 212-2008 "Proximate Analysis of Coal", the recovery rate and ash content of the coal are tested, and the test results are as follows:

[0100]

[0101] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A coal flotation agent, characterized in that: It comprises the following components by weight: 80-100 parts of oily sludge, 10-20 parts of chitosan composite microspheres, 10-15 parts of cyclohexanol, 5-10 parts of methyl amyl alcohol, 5-10 parts of sodium dodecyl sulfate, and 150-180 parts of water; The preparation method of the chitosan composite microspheres comprises the following steps: 1) dissolving chitosan in acetic acid solution to prepare a chitosan solution, dissolving sodium alginate in water to prepare a sodium alginate solution, mixing the chitosan solution and the sodium alginate solution, wherein the mass ratio of chitosan to sodium alginate is 1:0.8-1.3, to obtain a mixed solution A for standby use; 2) Mix liquid paraffin and span-80 to obtain a mixed solution B, and slowly drop the mixed solution A into the mixed solution B for emulsification to obtain an emulsion; 3) Adding glutaraldehyde cross-linking agent into the emulsion to carry out cross-linking reaction, and obtaining chitosan composite microspheres through centrifugal separation, washing and drying.

2. A coal flotation agent according to claim 1, characterized in that: The concentration of the chitosan solution in step 1) is 0.2-3 wt %.

3. A coal flotation agent according to claim 1, characterized in that: The concentration of the sodium alginate solution in step 1) is 1-5 wt %.

4. A coal flotation agent according to claim 1, characterized in that: In step 2), the volume ratio of the mixed solution A to the mixed solution B is 1:10-20.

5. A coal flotation agent according to claim 1, characterized in that: In the step 3), the amount of glutaraldehyde added is 0.5-1.0% of the mass of chitosan.

6. A method for preparing a coal flotation agent according to any one of claims 1 to 5, characterized in that: The following steps are involved: Mix the oily sludge, cyclohexanol, methylpentanol, sodium dodecyl sulfate and water, and stir at 600-800 r / min for 30-60 min to obtain a premix; Add chitosan composite microspheres into the premix, stir at 1000-1300 r / min for 20-30 min, and obtain a coal flotation agent.

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