Coal flotation agent and preparation method thereof

Abstract

The invention relates to the technical field of auxiliary chemicals, and discloses a coal flotation agent and a preparation method thereof. The specific method comprises the following steps: mixing the oily sludge, cyclohexanol, methyl amyl alcohol, lauryl sodium sulfate and water, and stirring to obtain a premix; and adding the chitosan composite microspheres into the premix, and continuously stirring to obtain the coal flotation agent. The method provided by the invention has a high removal rate on mineral substances in coal, reduces ash content generated by charcoal burning, and improves coal quality.

Description

Technical Field

[0001] The invention relates to the technical field of chemical additives, and in particular to a coal flotation agent 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, the 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 sort it into products of different particle sizes and uniform quality. Flotation is an economical method to achieve sorting based on the different surface hydrophobicity of coal particles and mineral impurities. In coal flotation, due to the complexity and unevenness of the surface of coal particles, flotation agents are usually added to enhance the hydrophobicity of coal particles in order to improve the flotation effect. That is, the oily substances in the flotation agent will be adsorbed, 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 float up, realizing the separation of coal particles and minerals. However, in the actual separation process, some minerals will be wrapped by oily substances and float up with the bubbles, causing the presence of some ash in the coal, affecting the quality of the coal. Summary of the invention

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

[0004] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions: A coal flotation agent, comprising the following components in parts by weight: 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.

[0005] The coal flotation agent of the present invention uses oily sludge as an oily component, cyclohexane and methylpentanol as a mixed foaming agent, and sodium dodecyl sulfate as an emulsifier. In the prior art, the oily component in the flotation agent is used to wrap coal particles to improve the hydrophobicity of the surface. The hydrophobic coal particles are easy to adhere to the surface of bubbles in the water, so that the coal particles float on the water surface, and the coal particles are separated from impurities. However, in the actual flotation process, the oily component in the flotation agent will also be partially wrapped on the surface of the mineral particles, resulting in some minerals being mixed in the coal, affecting the quality of the coal. The present invention reduces the minerals in coal and improves the purity of coal. Chitosan composite microsphere particles are added to a flotation agent. The surface of the chitosan composite microsphere is loaded with a large number of amino groups and hydroxyl groups, and has good hydrophilicity. The hydroxyl groups and amino groups on the surface of the chitosan composite microsphere form hydrogen bonding forces with the hydroxyl groups on the surface of the mineral, so that the chitosan composite microsphere is combined with the surface of the mineral particle, thereby greatly improving the hydrophilicity of the surface of the mineral particle. Since the surface of the mineral has extremely strong hydrophilicity, the surface of the mineral has a strong repelling force with the oily components in the flotation agent, so that the oily substances in the flotation machine are not easily wrapped on the surface of the mineral particles, thereby achieving complete separation of the coal particles and the minerals, significantly improving the purity of the coal particles after flotation, reducing the ash content in the coal, and thus improving the quality of the coal.

[0006] Preferably, the method for preparing 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 to obtain a mixed solution A for standby use; 2) Mixing liquid paraffin and span-80 to obtain a mixed solution B, slowly dropping 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.

[0007] In the technical solution of the present invention, since waste oily sludge is used as the oily component of the flotation agent, a further problem is that the oily sludge contains heavy metals, which will cause further pollution to the environment when mixed into coal combustion. In order to further solve this technical problem, the present invention prepares chitosan composite microspheres by chitosan and sodium alginate, and loads carboxyl groups in the chitosan composite microspheres. The carboxyl groups can form a complex with heavy metals, so that the heavy metals are combined with the chitosan composite microspheres. The chitosan composite microspheres are further combined with mineral particles in the coal, so that the coal particles are separated from the mineral particles and the heavy metals in the oily sludge are separated at the same time, thereby further improving the quality of the coal particles.

[0008] Preferably, the concentration of the chitosan solution in step 1) is 0.2-3 wt %.

[0009] Preferably, the concentration of the sodium alginate solution in step 1) is 1-5wt%.

[0010] Preferably, in step 1), the mass ratio of chitosan to sodium alginate is 1:0.8-1.3.

[0011] In the technical solution of the present invention, as described above, chitosan composite microspheres are prepared by chitosan and sodium alginate, so that carboxyl groups are loaded in the chitosan composite microspheres, and the carboxyl groups can form a complex with heavy metals, thereby achieving the purpose of removing heavy metals. In order for the chitosan composite microspheres to form a complex with heavy metals, the chitosan composite microspheres must be loaded with a sufficient amount of carboxyl groups, so 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 discovered that the mineral content in the coal after flotation increased significantly, that is, the ash content after combustion increased significantly, which was unexpected by the present invention team. This may be because as the amount of sodium alginate increases, the chitosan composite microspheres are loaded with excessive carboxyl groups, making the chitosan composite microspheres strongly negatively charged, which forms a strong repulsive force with the negatively charged minerals, preventing the chitosan composite microspheres from combining with the mineral particles, thereby increasing the mineral content in the coal and the ash content after the coal is burned. Therefore, the present invention also strictly controls the mass ratio of chitosan to sodium alginate to be greater than 1:1.3.

[0012] Preferably, in step 2), the volume ratio of the mixed solution A to the mixed solution B is 1:10-20.

[0013] Preferably, the amount of glutaraldehyde added in step 2) is 0.5-1.0% of the mass of chitosan.

[0014] A method for preparing a coal flotation agent comprises the following steps: 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.

[0015] The present invention has the following beneficial effects: Chitosan composite microsphere particles are added to the flotation agent. The surface of the chitosan composite microsphere is loaded with a large number of amino groups and hydroxyl groups, which have good hydrophilic properties. The hydroxyl groups and amino groups on the surface of the chitosan composite microspheres form hydrogen bonding forces with the hydroxyl groups on the surface of the minerals, so that the chitosan composite microspheres are combined with the surface of the mineral particles, thereby greatly improving the hydrophilic properties of the surface of the mineral particles. Since the surface of the mineral has extremely strong hydrophilicity, its surface has a strong repelling force with the oily components in the flotation agent, making it difficult for the oily substances in the flotation machine to be wrapped on the surface of the mineral particles, thereby achieving a thorough separation of the coal particles and the minerals, significantly improving the purity of the coal particles after flotation, reducing the ash content in the coal, and thus improving the quality of the coal; 2) Chitosan composite microspheres are prepared by chitosan and sodium alginate, and carboxyl groups are loaded in the chitosan composite microspheres. The carboxyl groups can form a complex with heavy metals, so that the heavy metals are bound to the chitosan composite microspheres. The chitosan composite microspheres are further combined with mineral particles in the coal, so that the coal particles are separated from the mineral particles and the heavy metals in the oily sludge are separated at the same time, thereby further improving the quality of the coal particles. DETAILED DESCRIPTION

[0016] 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.

[0017] 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.

[0018] The oily sludge used in the specific embodiment of the present invention is the oily sludge formed in the process of oil production.

[0019] Example 1: Preparation of chitosan composite microspheres: 1) dissolving chitosan in 2% by volume acetic acid solution to prepare a chitosan solution with a mass concentration of 2wt%, and dissolving sodium alginate in water to prepare a sodium alginate solution with a mass concentration of 4wt%; The chitosan solution and the sodium alginate solution are mixed, the mass ratio of chitosan to sodium alginate is 1:1.2, to obtain a mixed solution A for standby use; 2) Liquid paraffin and span-80 were mixed at a volume ratio of 50:2 to obtain a mixed solution B, and the mixed solution A was slowly added dropwise to the mixed solution B, with the volume ratio of the mixed solution A to the mixed solution B being 1:18, and the mixture was heated to 60° C. and stirred for emulsification for 50 minutes to obtain an emulsion; 3) Adding glutaraldehyde crosslinking agent to the emulsion, the amount of glutaraldehyde added is 0.9% of the mass of chitosan, and performing crosslinking reaction for 3 hours. After centrifugal separation, washing and drying, chitosan composite microspheres are obtained.

[0020] A coal flotation agent, comprising the following components in parts by weight: 95 parts of oily sludge, 18 parts of chitosan composite microspheres, 13 parts of cyclohexanol, 8 parts of methylpentanol, 9 parts of sodium dodecyl sulfate, and 170 parts of water.

[0021] A method for preparing a coal flotation agent comprises the following steps: The oily sludge, cyclohexanol, methylpentanol, sodium dodecyl sulfate and water were mixed and stirred at 700 r / min for 50 min to obtain a premix; Chitosan composite microspheres were added to the premix, and the mixture was stirred at 1200 r / min for 25 min to obtain a coal flotation agent.

[0022] Example 2: Preparation of chitosan composite microspheres: 1) dissolving chitosan in 2% by volume acetic acid solution to prepare a chitosan solution with a mass concentration of 0.8 wt%, and dissolving sodium alginate in water to prepare a sodium alginate solution with a mass concentration of 2 wt%; The chitosan solution and the sodium alginate solution are mixed, the mass ratio of chitosan to sodium alginate is 1:0.9, and a mixed solution A is obtained for later use; 2) Liquid paraffin and span-80 were mixed at a volume ratio of 50:2 to obtain a mixed solution B, and the mixed solution A was slowly added dropwise to the mixed solution B, with the volume ratio of the mixed solution A to the mixed solution B being 1:12, and the mixture was heated to 60° C. and stirred for emulsification for 50 minutes to obtain an emulsion; 3) Adding glutaraldehyde crosslinking agent to the emulsion, the amount of glutaraldehyde added is 0.6% of the mass of chitosan, and performing crosslinking reaction for 3 hours. After centrifugal separation, washing and drying, chitosan composite microspheres are obtained.

[0023] A coal flotation agent, comprising the following components in parts by weight: 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, and 160 parts of water.

[0024] A method for preparing a coal flotation agent comprises the following steps: The oily sludge, cyclohexanol, methylpentanol, sodium dodecyl sulfate and water were mixed and stirred at 700 r / min for 40 min to obtain a premix; Chitosan composite microspheres were added to the premix, and the mixture was stirred at 1200 r / min for 25 min to obtain a coal flotation agent.

[0025] Example 3: Preparation of chitosan composite microspheres: 1) dissolving chitosan in 2% by volume acetic acid solution to prepare a chitosan solution with a mass concentration of 1 wt%, and dissolving sodium alginate in water to prepare a sodium alginate solution with a mass concentration of 3 wt%; The chitosan solution and the sodium alginate solution are mixed, with the mass ratio of chitosan to sodium alginate being 1:1, to obtain a mixed solution A for later use; 2) Liquid paraffin and span-80 were mixed at a volume ratio of 50:2 to obtain a mixed solution B, and the mixed solution A was slowly added dropwise to the mixed solution B, with the volume ratio of the mixed solution A to the mixed solution B being 1:15, and the mixture was heated to 60° C. and stirred for emulsification for 50 minutes to obtain an emulsion; 3) Adding glutaraldehyde crosslinking agent to the emulsion, the amount of glutaraldehyde added is 0.8% of the mass of chitosan, and performing crosslinking reaction for 3 hours. After centrifugal separation, washing and drying, chitosan composite microspheres are obtained.

[0026] A coal flotation agent, comprising the following components in parts by weight: 90 parts of oily sludge, 15 parts of chitosan composite microspheres, 12 parts of cyclohexanol, 7 parts of methyl amyl alcohol, 8 parts of sodium dodecyl sulfate, and 170 parts of water.

[0027] A method for preparing a coal flotation agent comprises the following steps: The oily sludge, cyclohexanol, methylpentanol, sodium dodecyl sulfate and water were mixed and stirred at 700 r / min for 40 min to obtain a premix; Chitosan composite microspheres were added to the premix, and the mixture was stirred at 1200 r / min for 25 min to obtain a coal flotation agent.

[0028] Example 4: Preparation of chitosan composite microspheres: 1) dissolving chitosan in 2% by volume acetic acid solution to prepare a chitosan solution with a mass concentration of 3 wt%, and dissolving sodium alginate in water to prepare a sodium alginate solution with a mass concentration of 5 wt%; The chitosan solution and the sodium alginate solution are mixed, the mass ratio of chitosan to sodium alginate is 1:1.3, and a mixed solution A is obtained for later use; 2) Liquid paraffin and span-80 were mixed at a volume ratio of 50:2 to obtain a mixed solution B, and the mixed solution A was slowly added dropwise to the mixed solution B, with the volume ratio of the mixed solution A to the mixed solution B being 1:20, and the mixture was heated to 60° C. and stirred for emulsification for 50 minutes to obtain an emulsion; 3) Adding glutaraldehyde crosslinking agent to the emulsion, the amount of glutaraldehyde added is 1.0% of the mass of chitosan, and performing crosslinking reaction for 3 hours. After centrifugal separation, washing and drying, chitosan composite microspheres are obtained.

[0029] A coal flotation agent, comprising the following components in parts by weight: 100 parts of oily sludge, 20 parts of chitosan composite microspheres, 15 parts of cyclohexanol, 10 parts of methyl amyl alcohol, 10 parts of sodium dodecyl sulfate, and 180 parts of water.

[0030] A method for preparing a coal flotation agent comprises the following steps: The oily sludge, cyclohexanol, methylpentanol, sodium dodecyl sulfate and water were mixed and stirred at 800 r / min for 30 min to obtain a premix; Chitosan composite microspheres were added to the premix, and the mixture was stirred at 1300 r / min for 20 min to obtain a coal flotation agent.

[0031] Example 5: Preparation of chitosan composite microspheres: 1) dissolving chitosan in 2% by volume acetic acid solution to prepare a chitosan solution with a mass concentration of 0.2 wt%, and dissolving sodium alginate in water to prepare a sodium alginate solution with a mass concentration of 1 wt%; The chitosan solution and the sodium alginate solution are mixed, the mass ratio of chitosan to sodium alginate is 1:0.8, to obtain a mixed solution A for standby use; 2) Liquid paraffin and span-80 were mixed at a volume ratio of 50:2 to obtain a mixed solution B, and the mixed solution A was slowly added dropwise to the mixed solution B, with the volume ratio of the mixed solution A to the mixed solution B being 1:10, and the mixture was heated to 60° C. and stirred for emulsification for 50 minutes to obtain an emulsion; 3) Adding glutaraldehyde crosslinking agent to the emulsion, the amount of glutaraldehyde added is 0.5% of the mass of chitosan, and performing crosslinking reaction for 3 hours. After centrifugal separation, washing and drying, chitosan composite microspheres are obtained.

[0032] A coal flotation agent, comprising the following components in parts by weight: 80 parts of oily sludge, 10 parts of chitosan composite microspheres, 10 parts of cyclohexanol, 5 parts of methyl amyl alcohol, 5 parts of sodium dodecyl sulfate, and 150 parts of water.

[0033] A method for preparing a coal flotation agent comprises the following steps: The oily sludge, cyclohexanol, methylpentanol, sodium dodecyl sulfate and water were mixed and stirred at 600 r / min for 60 min to obtain a premix; Chitosan composite microspheres were added to the premix, and the mixture was stirred at 1000 r / min for 30 min to obtain a coal flotation agent.

[0034] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that: The coal flotation agent does not contain chitosan composite microspheres; The operation steps are the same as those in Example 1.

[0035] Comparative Example 2 The difference between Comparative Example 2 and Example 4 is that: The mass ratio of chitosan to sodium alginate is 1:1.4; The operation steps are the same as those in Example 4.

[0036] Comparative Example 3 The difference between Comparative Example 3 and Example 4 is that: The mass ratio of chitosan to sodium alginate is 1:1.5; The operation steps are the same as those in Example 4.

[0037] Comparative Example 4 The difference between Comparative Example 4 and Example 4 is that: The mass ratio of chitosan to sodium alginate is 1:1.6; The operation steps are the same as those in Example 4.

[0038] Comparative Example 5 The difference between Comparative Example 5 and Example 4 is that: The mass ratio of chitosan to sodium alginate is 1:1.7; The operation steps are the same as those in Example 4.

[0039] Performance Testing Take the raw coal particles and add water to prepare a slurry with a concentration of 100g / L, then add the flotation agents in the embodiment and the comparative example (dosage 0.1kg / t), 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 were tested according to the method of GB / T 212-2008 "Industrial Analysis Methods of Coal", and the test results are as follows:

[0040] 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 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 methylpentanol, 5-10 parts of sodium dodecyl sulfate, and 150-180 parts of water.

2. A coal flotation agent according to claim 1, characterized in that: 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 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.

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

4. A coal flotation agent according to claim 2, characterized in that: The concentration of the sodium alginate solution in step 1) is 1-5 wt %.

5. A coal flotation agent according to claim 2, characterized in that: In the step 1), the mass ratio of chitosan to sodium alginate is 1:0.8-1.

3.

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

7. A coal flotation agent according to claim 2, characterized in that: In the step 3), the amount of glutaraldehyde added is 0.5-1.0% of the mass of chitosan.

8. A method for preparing a coal flotation agent according to any one of claims 1 to 7, 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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