Method for enriching exinite in coal
By using ultrasonic vibration, water bath heating, and a density solution prepared with sodium hydroxide solution, benzene, and carbon tetrachloride, a highly efficient separation and high-purity enrichment of the crustacean and vitrinite was achieved. This method solves the problems of incomplete separation and difficult cleaning in existing technologies and is suitable for the preparation of scientific research samples of crustacean in coal.
Patent Information
- Application Number
- CN202411410270.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-10
- Publication Date
- 2025-01-10
AI Technical Summary
In existing technologies, the separation effect between chitinous and vitrinite is not ideal, and conventional sorting methods result in the loss of fine particles and difficulty in cleaning, making it difficult to efficiently enrich high-purity chitinous material.
The separation and enrichment of chitinous material were achieved by using ultrasonic vibration, water bath heating, and a density solution prepared with benzene and carbon tetrachloride at a concentration of 5-10% sodium hydroxide. This combination of physical and chemical methods, along with a simple filtration device, enabled the separation and enrichment of chitinous material.
It improves the separation purity and enrichment efficiency of chitinous plasmons, simplifies the operation steps, and solves the problems of incomplete separation and difficult cleaning in existing technologies. It is suitable for small-batch preparation of experimental samples in scientific research.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of coal chemistry and chemical engineering, and in particular to a method for enriching exinite in coal. Background Art
[0002] Coal is not a uniform substance. Its microscopic components are composed of vitrinite, inertinite and exinite. The exinite in coal is mainly composed of reproductive organs, protective tissues, secretory metabolites of higher plants, etc., and appears dark gray under oil-immersion reflected light. Exinite is the microscopic component with the highest hydrogen content. It is closely related to the calorific value, volatile matter and other properties of coal, and is an important component of concern in the study of coal liquefaction technology.
[0003] At present, the separation and enrichment methods of microscopic components include hand selection, density floating and sinking, flotation and other methods. Among them, there are relatively more separation methods for vitrinite and inertinite, while the separation and enrichment of exinite has always been a difficult problem in this field. At present, the enrichment method for exinite is mainly the floating and sinking method, that is, the exinite is separated by the difference in the density of the three microscopic components. The exinite and the inertinite can be effectively separated by floating and sinking experiments, but because the exinite and the vitrinite mostly present interdependent occurrence forms, the separation effect of the exinite and the vitrinite is not ideal. At the same time, the conventional sorting density liquid uses zinc chloride solution, which will cause difficulties in the later cleaning process for fine particles of 200 mesh, and the collected samples will also be lost in repeated cleaning.
[0004] Therefore, in order to solve the above problems, it is necessary to propose an experimental method with simple operation, high exinite dissociation and enrichment efficiency, and high separation purity to obtain high-content exinite in coal. Summary of the invention
[0005] The object of the present invention is to provide a method for enriching exinite in coal. By combining physical and chemical methods, exinite can be separated from vitrinite. The method of the present invention has high dissociation efficiency and high separation purity for exinite.
[0006] In order to achieve the above object, the present invention adopts the following technical solutions:
[0007] A method for enriching exinite in coal comprises the following steps:
[0008] (1) pre-treating the sample and crushing the pre-treated sample;
[0009] (2) adding a sodium hydroxide solution with a concentration of 5 to 10% to the crushed sample, maintaining the solution under ultrasonic vibration and a water bath temperature of 40 to 60° C. for a period of time to completely separate the exinite from the vitrinite;
[0010] (3) filtering the sample crushed in step (2) with a filtering device, and washing with water until the filtered aqueous solution is neutral;
[0011] (4) drying the sample filtered in step (3); and then using benzene and carbon tetrachloride to prepare a solution with a density of 1.20 g / cm 3 Density liquid;
[0012] (5) adding a portion of the dried sample to a centrifuge tube, adding density liquid to the centrifuge tube to mix it evenly with the dried sample, and placing the tube in a centrifuge for centrifugal treatment;
[0013] (6) After centrifugation, the floating matter is filtered out by a filtering device, and the floating matter is dried to obtain a high-purity exinite group.
[0014] In the above-mentioned method for enriching exinite in coal, in step (1), the pretreatment of the sample includes: testing the raw coal crushed to 3 mm according to the provisions of GB / T478-2008 "Coal Floatation and Sinking Test Method" to obtain a density less than 1.30 g / cm 3 The obtained samples are washed with clean water and the zinc chloride is cleaned; the washed samples are dried.
[0015] In the above-mentioned method for enriching exinin in coal, in step (1), during drying, the cleaned sample is spread flat with a thickness of ≤5 mm, the drying temperature is 45-55° C., and the drying time is 3-5 hours.
[0016] In the above-mentioned method for enriching exinin in coal, in step (1), the pretreated sample is crushed to 100-325 mesh, and the particle size of the crushed sample is 0.045-0.15 mm.
[0017] In the above-mentioned method for enriching exinite in coal, in step (2), the ultrasonic vibration is maintained for 60 to 120 minutes with the water bath temperature maintained at 40 to 60° C.; the frequency of the ultrasonic vibration is 20 to 50 kHz.
[0018] In the above-mentioned method for enriching exinite in coal, in step (4), during drying, the thickness of the filtered sample is ≤5 mm, the drying temperature is 45-55° C., and the drying time is 3-5 hours.
[0019] In the above-mentioned method for enriching exinin in coal, in step (5), the dried coal sample is added to a centrifuge tube, the amount of which is maintained at about 1 / 10 of the volume of the centrifuge tube, the speed of the centrifuge is 2500-3500 r / min, and the centrifugation time is 3-7 min.
[0020] In the above-mentioned method for enriching exinite in coal, in step (6), the drying temperature is 45-55° C. and the drying time is ≥12 h.
[0021] In the above-mentioned method for enriching exinite in coal, the filtering devices in step (3) and step (6) are both simple filtering devices composed of a beaker, a funnel and filter paper.
[0022] In the above-mentioned method for enriching exinite in coal, in step (5), the density liquid and the dried sample are mixed evenly by shaking.
[0023] Compared with the prior art, the present invention brings the following beneficial technical effects:
[0024] (1) The present invention firstly utilizes ultrasonic vibration, water bath heating and a sodium hydroxide solution with a concentration of 5-10% to promote the dissociation of the exininite and vitrinite in the coal sample; during the dissociation process, it can also react with the minerals in the coal to a certain extent, avoiding the combination of minerals and organic matter that affects the separation and enrichment of the exininite. The separated exininite has high purity and can effectively meet the research needs; on the basis of the complete dissociation of the exininite and vitrinite, the present invention utilizes a density liquid prepared by benzene and carbon tetrachloride to further centrifuge the same, which can further improve the separation efficiency and solve the cleaning problem and wastewater problem generated by the separation using zinc chloride density liquid in the prior art.
[0025] (2) The present invention only requires a simple filtering device consisting of a beaker and a funnel to perform filtering, and the operation threshold is low and the operation steps are simple; the density range for separation of the specific exin group is clearly pointed out, which can effectively improve the separation efficiency.
[0026] (3) The separation and enrichment efficiency of the present invention is high, and the separated exinite has high purity, and can be used for small-batch preparation of test samples in scientific research institutes. DETAILED DESCRIPTION
[0027] The present invention proposes a method for enriching exinite in coal. In order to make the advantages and technical solutions of the present invention clearer and more specific, the present invention is further described below in conjunction with specific embodiments.
[0028] The raw materials described in the present invention can be purchased through commercial channels.
[0029] A method for enriching exinite in coal comprises the following steps:
[0030] (1) The raw coal crushed to 3 mm was tested according to the provisions of GB / T478-2008 "Coal Floatation and Sinking Test Method" to obtain a density less than 1.30 g / cm 3The sample is washed with clean water and the zinc chloride is cleaned; the washed sample is dried. During drying, the thickness of the washed sample is ≤5mm, the drying temperature is 45-55℃, and the drying time is 3-5h. The pretreated sample is crushed to 100-325 mesh, and the particle size of the crushed sample is 0.045-0.15mm.
[0031] The pretreated samples are crushed to 100 mesh, 200 mesh or 325 mesh, and the particle size of the crushed samples is 0.15 mm, 0.075 mm or 0.045 mm.
[0032] The above-mentioned drying temperature can be 45°C, 50°C, 55°C, etc., preferably 50°C, and the drying time can be 3h, 4h, 5h, etc., preferably 4h.
[0033] (2) Adding a sodium hydroxide solution with a concentration of 5 to 10% to the crushed sample, maintaining the solution under ultrasonic vibration and a water bath temperature of 40 to 60° C. for 15 to 25 minutes, completely separating the exinite from the vitrinite.
[0034] The above-mentioned maintenance time can be 15 minutes, 20 minutes, 22 minutes, 25 minutes, etc., and the preferred maintenance time in the present invention is 20 minutes, during which the exinite can be completely separated from the vitrinite.
[0035] (3) Filter out the sample crushed in step (2) using a filtering device, and repeatedly wash it with a large amount of ultrapure water until the filtered aqueous solution is neutral.
[0036] The above-mentioned filtering device is a simple filtering device composed of a beaker, a funnel and filter paper, so the operation threshold is low, and the crushed sample can be filtered out through the simple filtering device.
[0037] (4) drying the sample filtered in step (3) at a temperature of 45 to 55° C. for 3 to 5 h; and then using benzene and carbon tetrachloride to prepare a solution having a density of 1.20 g / cm 3 density liquid.
[0038] In order to ensure the drying effect, the present invention preferably spreads the filtered sample flat with a thickness of ≤5 mm. The above-mentioned drying temperature can be 45°C, 50°C, 55°C, etc., preferably 50°C, and the drying time can be 3h, 4h, 5h, etc., preferably 4h.
[0039] (5) Add the dried sample to a centrifuge tube, maintaining the amount at about 1 / 10 of the volume of the centrifuge tube, and add density liquid to the centrifuge tube to mix it with the dried sample evenly. Preferably, the density liquid and the dried sample are mixed evenly by shaking, and then placed in a centrifuge for centrifugal treatment.
[0040] Preferably, the speed of the centrifuge is 2500-3500 r / min, and the centrifugation time is 3-7 min; more preferably, the speed of the centrifuge is 3000 r / min, and the centrifugation time is 5 min.
[0041] (6) After centrifugation, the floating matter is filtered out by a filtering device, and the floating matter is dried at a temperature of 45 to 55° C. for a drying time of ≥12 h to obtain a high-purity exinite group.
[0042] In the above-mentioned method for enriching exinin in coal, in step (5), the dried coal sample is added to a centrifuge tube, the amount of which is maintained at about 1 / 10 of the volume of the centrifuge tube, the speed of the centrifuge is 2500-3000 r / min, and the centrifugation time is 3-7 min.
[0043] The present invention will be further described below in conjunction with specific embodiments.
[0044] Embodiment 1:
[0045] A method for enriching exinite in coal comprises the following steps:
[0046] (1) 2 kg of raw coal crushed to 3 mm was tested according to the provisions of GB / T478-2008 "Coal Floatation and Sinking Test Method" to obtain a density of less than 1.3 g / cm 3 The sample was washed with clean water and the zinc chloride was cleaned; the washed sample was dried. During drying, the washed sample was laid flat with a thickness of ≤5mm, the drying temperature was 50℃, and the drying time was 4h. The pretreated sample was crushed to 100 mesh, and the particle size of the crushed sample was 0.15mm.
[0047] (2) A 5% sodium hydroxide solution was added to the crushed sample, and maintained for 20 minutes under the conditions of ultrasonic vibration and a water bath temperature of 40° C. to completely separate the exinite from the vitrinite.
[0048] (3) Filter out the sample crushed in step (2) using a filtering device, and repeatedly wash it with a large amount of ultrapure water until the filtered aqueous solution is neutral.
[0049] (4) The sample filtered in step (3) was dried at a temperature of 50° C. for 4 h; and then a density of 1.20 g / cm was prepared using benzene and carbon tetrachloride. 3 density liquid.
[0050] (5) Add the dried sample to a centrifuge tube, maintaining the amount at about 1 / 10 of the volume of the centrifuge tube, and add density liquid to the centrifuge tube to mix it with the dried sample evenly. Preferably, the density liquid and the dried sample are mixed evenly by shaking, and then placed in a centrifuge for centrifugation. The speed of the centrifuge is 3000 r / min, and the centrifugation time is 5 min.
[0051] (6) After centrifugation, the floating matter is filtered out by a filtering device, and the floating matter is dried at a drying temperature of 50° C. for a drying time of ≥ 12 h to ensure that the organic solvent in the coal is completely volatilized to obtain the exinite.
[0052] The samples were tested. A small amount of the dried samples were taken and used to make coal rock slides using resin, which were then ground and polished. The samples were quantitatively analyzed under a polarizing microscope at 500 times magnification. The analysis results are shown in Table 1.
[0053] Comparative Example 1:
[0054] A method for enriching exinite in coal comprises the following steps:
[0055] (1) 2 kg of raw coal crushed to 3 mm was tested according to the provisions of GB / T478-2008 "Coal Floatation and Sinking Test Method" to obtain a density of less than 1.3 g / cm 3 The sample was washed with clean water and the zinc chloride was cleaned; the washed sample was dried. During drying, the washed sample was laid flat with a thickness of ≤5mm, the drying temperature was 50℃, and the drying time was 4h. The pretreated sample was crushed to 100 mesh.
[0056] (2) Add a solution of benzene and carbon tetrachloride with a density of 1.20 g / cm to the crushed sample. 3 density liquid.
[0057] (3) Add the sample to a centrifuge tube, maintaining the amount at about 1 / 10 of the volume of the centrifuge tube, and add density liquid to the centrifuge tube to mix it with the sample evenly. Preferably, the density liquid and the sample are mixed evenly by shaking, and then placed in a centrifuge for centrifugation at a speed of 3000 r / min and a centrifugation time of 5 min.
[0058] (4) After centrifugation, the floating matter is filtered out by a filtering device, and the floating matter is dried at a drying temperature of 50° C. for a drying time of ≥ 12 h to ensure that the organic solvent in the coal is completely volatilized to obtain the exinite.
[0059] The samples were tested. A small amount of the dried samples were taken and used to make coal rock slides using resin, which were then ground and polished. The samples were quantitatively analyzed under a polarizing microscope at 500 times magnification. The analysis results are shown in Table 1.
[0060] Table 1 Microscopic component content of samples (%)
[0061] sample Vitrinite Inertinite Exinite Minerals As is 76.1 10.1 9.3 4.5 Example 1 63.6 4.7 29.6 2.1 Comparative Example 1 68.1 9.2 18.1 4.6
[0062] Embodiment 2:
[0063] A method for enriching exinite in coal comprises the following steps:
[0064] (1) The raw coal crushed to 3 mm was tested according to the provisions of GB / T478-2008 "Coal Floatation and Sinking Test Method" to obtain a density less than 1.30 g / cm 3 The sample was washed with clean water and the zinc chloride was cleaned; the washed sample was dried. During drying, the washed sample was laid flat with a thickness of ≤5mm, the drying temperature was 45℃, and the drying time was 3h. The pretreated sample was crushed to 200 mesh, and the particle size of the crushed sample was 0.075mm.
[0065] (2) A 10% sodium hydroxide solution was added to the crushed sample, and maintained at 60° C. in a water bath for 25 min to completely separate the exinite from the vitrinite.
[0066] (3) Filter out the sample crushed in step (2) using a filtering device, and repeatedly wash it with a large amount of ultrapure water until the filtered aqueous solution is neutral.
[0067] (4) The sample filtered in step (3) was dried at a temperature of 45° C. for 3 h; and then a density of 1.20 g / cm was prepared using benzene and carbon tetrachloride. 3 density liquid.
[0068] (5) Add the dried sample to a centrifuge tube, maintaining the amount at about 1 / 10 of the volume of the centrifuge tube, and add density liquid to the centrifuge tube to mix it with the dried sample evenly. Preferably, the density liquid and the dried sample are mixed evenly by shaking, and then placed in a centrifuge for centrifugation. The speed of the centrifuge is 2500 r / min, and the centrifugation time is 3 min.
[0069] (6) After centrifugation, the floating matter is filtered out by a filtering device, and the floating matter is dried at a temperature of 45° C. for a drying time of ≥12 h to obtain the exinite.
[0070] The samples were tested. A small amount of the dried samples were taken and used to make coal rock slides using resin, which were then ground and polished. The samples were quantitatively analyzed under a polarizing microscope at 500 times magnification. The analysis results are shown in Table 2.
[0071] Comparative Example 2:
[0072] A method for enriching exinite in coal comprises the following steps:
[0073] (1) The raw coal crushed to 3 mm was tested according to the provisions of GB / T478-2008 "Coal Floatation and Sinking Test Method" to obtain a density less than 1.3 g / cm 3 The sample was washed with clean water and the zinc chloride was cleaned; the washed sample was dried. During drying, the washed sample was laid flat with a thickness of ≤5mm, the drying temperature was 45℃, and the drying time was 3h. The pretreated sample was crushed to 200 mesh.
[0074] (2) The density of benzene and carbon tetrachloride is 1.20 g / cm 3 density liquid.
[0075] (3) Add the dried sample to a centrifuge tube, maintaining the amount at about 1 / 10 of the volume of the centrifuge tube, and add density liquid to the centrifuge tube to mix it with the dried sample evenly. Preferably, the density liquid and the dried sample are mixed evenly by shaking, and then placed in a centrifuge for centrifugation. The speed of the centrifuge is 2500 r / min, and the centrifugation time is 3 min.
[0076] (4) After centrifugation, the floating matter is filtered out by a filtering device, and the floating matter is dried at a temperature of 45° C. for a drying time of ≥12 h to obtain the exinite group.
[0077] The samples were tested. A small amount of the dried samples were taken and used to make coal rock slides using resin, which were then ground and polished. The samples were quantitatively analyzed under a polarizing microscope at 500 times magnification. The analysis results are shown in Table 2.
[0078] Table 2 Microscopic component content of samples (%)
[0079] sample Vitrinite Inertinite Exinite Minerals As is 76.1 10.1 9.3 4.5 Example 2 47.6 3.5 47.7 1.2 Comparative Example 2 51.3 7.2 36.1 5.4
[0080] Embodiment 3:
[0081] A method for enriching exinite in coal comprises the following steps:
[0082] (1) The raw coal crushed to 3 mm was tested according to the provisions of GB / T478-2008 "Coal Floatation and Sinking Test Method" to obtain a density less than 1.30 g / cm 3 The sample was washed with clean water and the zinc chloride was cleaned; the washed sample was dried. During drying, the washed sample was laid flat with a thickness of ≤5mm, the drying temperature was 55℃, and the drying time was 5h. The pretreated sample was crushed to 325 mesh, and the particle size of the crushed sample was 0.045mm.
[0083] (2) Adding an 8% sodium hydroxide solution to the crushed sample, maintaining the solution for 25 min under ultrasonic vibration and a water bath temperature of 50° C., completely separates the exinite from the vitrinite.
[0084] (3) Filter out the sample crushed in step (2) using a filtering device, and repeatedly wash it with a large amount of ultrapure water until the filtered aqueous solution is neutral.
[0085] (4) The sample filtered in step (3) was dried at a temperature of 55° C. for 5 h; and then a density of 1.20 g / cm was prepared using benzene and carbon tetrachloride. 3 density liquid.
[0086] (5) Add the dried sample to a centrifuge tube, maintaining the amount at about 1 / 10 of the volume of the centrifuge tube, and add density liquid to the centrifuge tube to mix it with the dried sample evenly. Preferably, the density liquid and the dried sample are mixed evenly by shaking, and then placed in a centrifuge for centrifugation. The speed of the centrifuge is 3500 r / min, and the centrifugation time is 7 min.
[0087] (6) After centrifugation, the floating matter is filtered out by a filtering device, and the floating matter is dried at a temperature of 55° C. for a drying time of ≥12 h to obtain the exinite.
[0088] The samples were tested. A small amount of the dried samples were taken and used to make coal rock slides using resin, which were then ground and polished. The samples were quantitatively analyzed under a polarizing microscope at 500 times magnification. The analysis results are shown in Table 3.
[0089] Comparative Example 3:
[0090] A method for enriching exinite in coal comprises the following steps:
[0091] (1) The raw coal crushed to 3 mm was tested according to the provisions of GB / T478-2008 "Coal Floatation and Sinking Test Method" to obtain a density less than 1.30 g / cm 3 The sample was washed with clean water and the zinc chloride was cleaned; the washed sample was dried. During drying, the washed sample was laid flat with a thickness of ≤5mm, the drying temperature was 55℃, and the drying time was 5h. The pretreated sample was crushed to 325 mesh, and the particle size of the crushed sample was 0.045mm.
[0092] (2) Using benzene and carbon tetrachloride, the density is 1.20 g / cm 3 density liquid.
[0093] (3) The dried sample is added to a centrifuge tube, the amount of which is maintained at about 1 / 10 of the volume of the centrifuge tube, and a density liquid is added to the centrifuge tube to mix it with the dried sample evenly. Preferably, the density liquid and the dried sample are mixed evenly by shaking, and then placed in a centrifuge for centrifugation. The speed of the centrifuge is 3500 r / min, and the centrifugation time is 7 min.
[0094] (4) After centrifugation, the floating matter is filtered out by a filtering device, and the floating matter is dried at a drying temperature of 55° C. for a drying time of ≥12 h to obtain the exinite group.
[0095] The samples were tested. A small amount of the dried samples were taken and used to make coal rock slides using resin, which were then ground and polished. The samples were quantitatively analyzed under a polarizing microscope at 500 times magnification. The analysis results are shown in Table 3.
[0096] Table 3 Microscopic component content of samples (%)
[0097]
[0098]
[0099] In summary, the present invention utilizes "low concentration alkaline solution (5-10%) + microwave vibration + water bath heating treatment" to not only promote the separation of exinite and vitrinite in coal, but also react with minerals in coal to a certain extent, avoiding the combination of minerals and organic matter that affects the separation and enrichment of exinite. The method of the present invention has high enrichment efficiency and is simple to operate, and can be promoted and applied.
[0100] Parts not described in the present invention can be implemented by those skilled in the art by referring to the existing technology.
[0101] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to be limiting of the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments should fall within the scope of protection of the claims of the present application.
Claims
1. A method for enriching exinite in coal, characterized in that: The following steps are involved: (1) pre-treating the sample and crushing the pre-treated sample; (2) adding a sodium hydroxide solution with a concentration of 5 to 10% to the crushed sample, maintaining the solution under ultrasonic vibration and a water bath temperature of 40 to 60° C. for a period of time to completely separate the exinite from the vitrinite; (3) filtering the sample crushed in step (2) with a filtering device, and washing with water until the filtered aqueous solution is neutral; (4) drying the sample filtered in step (3); and then using benzene and carbon tetrachloride to prepare a solution with a density of 1.20 g / cm 3 Density liquid; (5) adding a portion of the dried sample to a centrifuge tube, adding density liquid to the centrifuge tube to mix it evenly with the dried sample, and placing the tube in a centrifuge for centrifugal treatment; (6) After centrifugation, the floating matter is filtered out by a filtering device, and the floating matter is dried to obtain an exinite group with a purity of more than 80%.
2. The method for enriching exinite in coal according to claim 1, characterized in that: In step (1), the sample is pre-treated by: crushing the raw coal to 3 mm and testing it according to the provisions of GB / T478-2008 "Coal Floatation and Sinking Test Method" to obtain a density less than 1.30 g / cm 3 The obtained samples are washed with clean water to clean the zinc chloride; the washed samples are dried.
3. The method for enriching exinite in coal according to claim 2, characterized in that: In step (1), during drying, the cleaned sample is laid flat with a thickness of ≤5 mm, the drying temperature is 45-55° C., and the drying time is 3-5 h.
4. The method for enriching exinite in coal according to claim 3, characterized in that: In step (1), the pretreated sample is crushed to 100-325 mesh, and the particle size of the crushed sample is 0.045-0.15 mm.
5. The method for enriching exinite in coal according to claim 1, characterized in that: In step (2), the ultrasonic vibration is maintained for 60 to 120 minutes with the water bath temperature maintained at 40 to 60° C.; the frequency of the ultrasonic vibration is 20 to 50 kHz.
6. The method for enriching exinite in coal according to claim 1, characterized in that: In step (4), during drying, the filtered sample is spread flat with a thickness of ≤5 mm, the drying temperature is 45-55° C., and the drying time is 3-5 h.
7. The method for enriching exinite in coal according to claim 1, characterized in that: In step (5), the dried sample is added to a centrifuge tube, the sample volume is maintained at about 1 / 10 of the volume of the centrifuge tube, the speed of the centrifuge is 2500-3500 r / min, and the centrifugation time is 3-7 min.
8. The method for enriching exinite in coal according to claim 1, characterized in that: In step (6), the drying temperature is 45-55° C. and the drying time is ≥12 h.
9. The method for enriching exinite in coal according to claim 1, characterized in that: The filtering devices in step (3) and step (6) are both simple filtering devices consisting of a beaker, a funnel and filter paper.
10. The method for enriching exinite in coal according to claim 1, characterized in that: In step (5), the density liquid and the dried sample are mixed evenly by shaking.