Method for measuring content of quinoline insoluble in coal pitch

Abstract

The invention discloses a method for determining the content of quinoline insoluble substances in coal pitch, and belongs to the technical field of coal pitch. The determination method comprises the following steps: dissolving a coal pitch sample with quinoline, carrying out suction filtration, washing residues with hot quinoline and absolute ethyl alcohol in sequence, carrying out suction filtration again, drying, weighing, and calculating the mass fraction of the quinoline insoluble substance in the coal pitch. Wherein in the suction filtration and the secondary suction filtration, a mixture of calcium carbonate and diatomite is used as a filter aid, and the mass ratio of the calcium carbonate to the diatomite is 6: (4-4.5). The method is used for solving the technical problems that an existing measuring method is inaccurate in measuring result and low in detection efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of coal tar pitch, and in particular relates to a method for determining the content of quinoline insoluble matter in coal tar pitch. Background Art

[0002] Coal tar is the heavy residue left after coal tar is distilled and cut off the fraction at about 450°C under the vacuum process. The volume density at room temperature is 1.20g / cm 3 ~1.35g / cm 3 A black solid that softens when heated to a certain temperature. It is composed of aromatic compounds with three or more rings, oxygen-containing, nitrogen-containing, sulfur-containing heterocyclic compounds, and a small amount of high-molecular carbon substances. Coal tar can be divided into medium-temperature asphalt and high-temperature asphalt according to the softening point.

[0003] The content of quinoline insoluble matter in coal tar is an important indicator for evaluating the quality of coal tar. Therefore, it is very important to quickly, accurately and safely determine the content of quinoline insoluble matter in coal tar. At present, the determination of quinoline insoluble matter in coal tar is based on the "GB / T 2293-2019 Test Method for Quinoline Insoluble Matter in Coking Asphalt Products".

[0004] For example, the above-mentioned existing method involves using two highly toxic toluene and acetone as washing solvents to dissolve quinoline in asphalt and wash the cleaning solvent. Toluene and acetone are used in large quantities, and the purchase, storage, and use are strictly controlled and the conditions are relatively strict. At the same time, toluene and acetone are very harmful to the body of the experimenter, and long-term use and contact affect the health of the experimenter. According to the existing standard technology, the combination of toluene and acetone as solvents will inevitably have technical problems such as long analysis time and low detection efficiency. In addition, the use of filter aids is crucial to improving product quality and filtration efficiency in chemical experiments and industrial production processes. In the above-mentioned "GB / T 2293-2019 Test Method for Quinoline Insoluble Matter in Coking Asphalt Products", diatomaceous earth, as a natural inorganic material, is used as a filter aid due to its good adsorption, stability and corrosion resistance. However, if only diatomaceous earth is used as a filter aid, the diatomaceous earth will be tightly attached to the filter medium during the analysis process to form a dense filter cake. Although this layer of filter cake has a certain filtering effect, it will also increase the risk of clogging and reduce the filtration accuracy, thereby affecting the accuracy of the measurement results. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method for determining the quinoline insoluble content of coal tar pitch, so as to solve the technical problems of inaccurate determination results and low detection efficiency of the existing determination methods.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for determining the content of quinoline insoluble matter in coal tar pitch, comprising the following steps: The coal tar pitch sample was dissolved with quinoline, then filtered, and the residue was washed with hot quinoline and anhydrous ethanol in turn and filtered again, and the mass fraction of quinoline insoluble matter in coal tar pitch was calculated by drying and weighing. Wherein, a mixture of calcium carbonate and diatomaceous earth is used as a filter aid in both suction filtration and re-filtration, and the mass ratio of calcium carbonate to diatomaceous earth is 6: (4~4.5).

[0007] In one embodiment, the process of dissolving the coal tar pitch sample using quinoline is as follows: Place the quinoline and coal tar samples in a constant temperature water bath at 75±5°C and continue stirring for 30 min to complete dissolution.

[0008] In one embodiment, the temperature of the hot quinoline is 75±5°C.

[0009] In one embodiment, the total amount of anhydrous ethanol used for washing is 30 mL to 100 mL.

[0010] In one embodiment, the washing with anhydrous ethanol is performed at least three times.

[0011] In one embodiment, the amount of anhydrous ethanol used for each washing is 10-30 mL.

[0012] In one embodiment, the washing with anhydrous ethanol is terminated when the filtrate becomes colorless and transparent.

[0013] In one embodiment, the second filtration time is 5 minutes.

[0014] In one embodiment, the drying temperature is 115-120° C., and the drying time is 90 min.

[0015] In one embodiment, the particle size of the calcium carbonate ranges from 40 mesh to 60 mesh.

[0016] In one embodiment, the mass fraction of quinoline insoluble matter in coal tar pitch is the ratio of the difference between the total mass of the filter, the filter aid and the quinoline insoluble matter in coal tar pitch and the mass of the filter and the filter aid to the mass of the coal tar pitch sample.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The invention provides a method for determining the content of quinoline insoluble matter in coal tar. In the determination process of quinoline insoluble matter in coal tar, anhydrous ethanol can be used to effectively remove residual impurities and improve the accuracy of determination. Anhydrous ethanol is used as a solvent, and its high purity and good solubility are helpful for further purification of quinoline insoluble matter and reducing the influence of other organic impurities. Compared with toluene and acetone, anhydrous ethanol has a wider solubility range, can more thoroughly clean the residue, and improve the accuracy of determination. The method uses low-toxic reagent anhydrous ethanol as a leaching solvent for quinoline washing residue, replaces traditional toluene and acetone, and can accurately and safely complete the determination. And compared with the existing toluene and acetone, the use of anhydrous ethanol can effectively reduce the amount of quinoline and washing residue solvents, shorten the analysis time, and realize the rapid, accurate and safe detection of the content of quinoline insoluble matter in coal tar. Further, calcium carbonate is mixed with diatomaceous earth as a filter aid, and diatomaceous earth has a porous structure, a large pore specific surface area, and abundant internal micropores, which helps to quickly intercept impurities with smaller particle sizes during the filtration process. The addition of calcium carbonate further enhances the filtration performance of the mixed filter aid, accelerating the filtration process by providing more filtration surface area and optimizing particle distribution. The physical and chemical properties of calcium carbonate and diatomaceous earth complement each other, and after mixing, they can form a more uniform filter layer, which helps to speed up the filtration speed. The particle structure of calcium carbonate helps to improve the permeability of the filter medium, making it easier for liquid to pass through, thereby shortening the filtration time. The use of mixed filter aids makes the filter cake structure looser, easier to wash and filter, and helps to reduce the insoluble content in the filtrate, thereby further improving the measurement speed. Washing with anhydrous ethanol can remove residual impurities, including residual filter aid components, thereby ensuring the accuracy of the drying and weighing steps and improving the calculation accuracy of the mass fraction of quinoline insolubles in coal tar. The use of mixed filter aids reduces clogging, making the results of each measurement more stable and reliable. This helps to reduce experimental errors, improve data accuracy, and more accurately evaluate the content of quinoline insolubles in coal tar. In addition, the mixture of calcium carbonate and diatomaceous earth is easy to clean after use without affecting the filtration effect. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0019] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0020] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0021] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0022] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0023] The method for determining the content of quinoline insoluble matter in coal tar provided in the prior art "GB / T 2293-2019 Test Method for Quinoline Insoluble Matter in Coking Asphalt Products" is as follows: 1. Test Principle A certain mass of sample is dissolved with quinoline under specified test conditions, the insoluble matter is filtered, washed and dried, and then its mass fraction is calculated.

[0024] 2. Instruments and Reagents instrument Beaker: 100mL Weighing bottle: 35mm diameter, 70mm or 75mm high, with tight ground cover Dryer: Built-in desiccant Constant temperature water bath: temperature controlled at (75±5)℃ Filter bottle: volume 500mL~1000mL Vacuum pump: 1L / s, ultimate vacuum degree 0.06kPa~0.067kPa Blast drying oven Filter: Glass sand core filter crucible, diameter 40mm, G4. Before use, it needs to be boiled in hydrochloric acid, cleaned with laboratory water, dried to constant weight in a drying oven at (105℃~110℃), and stored in a desiccator for future use.

[0025] Filter paper: medium-speed quantitative filter paper, diameter 125mm. Soak the filter paper in toluene for 24 hours, take it out and dry it, dry it in a drying oven at (105℃~110℃) to constant weight, and store it in a desiccator for future use.

[0026] Hard glass washing bottle: volume 200mL~500mL, with scale Centrifuge: speed (0~4000) r / min, centrifugal test tube 50mL Balance: Sensitivity 0.0001g Sieve: SSω500 / 315μm sieve in accordance with GB / T 6005 Glass funnel: diameter 80mm Reagents Quinoline: analytically pure or chemically pure with a purity of more than 95% Toluene: analytical grade Acetone: analytical grade Diatomaceous earth: analytically pure, fineness 40~60 mesh. Rinse the diatomaceous earth in a glass sand core filter crucible with laboratory water, filter and dry in a drying oven to constant weight (2h~2.5h), then cool in a desiccator to room temperature for use.

[0027] 3. Sample collection and preparation The sampling of samples shall be carried out in accordance with the provisions of GB / T 1999 and GB / T 2000. The preparation of samples shall be carried out in accordance with the provisions of GB / T 2291. After drying, the samples shall be ground into particles passing through the SSω500 / 315μm sieve in a mortar. For soft asphalt samples, the samples shall be melted and stirred evenly to ensure that the melting temperature does not exceed 150℃ and the melting time does not exceed 10min.

[0028] 4. Test steps Accurately weigh the sample: weigh the sample whose quinoline insoluble content meets the requirement of 75~150mg, and weigh to 0.0002g. Coal tar and asphalt samples are placed in a clean and dry 100mL beaker, and modified asphalt samples are placed in a centrifuge tube.

[0029] Add quinoline and stir: Add 25 mL of quinoline and stir evenly with a glass rod.

[0030] Dissolving by heating: Immerse the beaker or centrifuge tube containing the sample and the washing bottle containing quinoline in a constant temperature water bath of (75±5)℃, stirring occasionally. Take out after 30 minutes and prepare for filtration.

[0031] Rinse the glass rod used for stirring with hot quinoline and place the washing liquid in the beaker or centrifuge tube containing the sample.

[0032] Filtration: The centrifugal test tube containing the modified asphalt sample should be placed in a centrifuge and centrifuged at 4000r / min for 20 minutes, then taken out and filtered.

[0033] Install the filter device, add 2g~3g of dry diatomaceous earth to the clean and dry filter that has been constant weight, and weigh the whole thing to an accuracy of 0.0001g.

[0034] Soak the diatomaceous earth in the filter with a small amount of quinoline, slowly introduce the dissolved sample into the filter, and filter it at the same time.

[0035] washing: Use 30 mL of hot quinoline to wash the beaker or centrifuge tube several times to transfer all the residue to the filter. Then use about 50 or 30 mL of hot quinoline several times (about 10 mL each time) to wash the residue in the filter and filter it at the same time. The temperature of quinoline should be maintained during filtration.

[0036] After washing with hot quinoline and filtering, use about 100 mL of hot toluene to filter and wash 7 to 8 times until there is no obvious yellow color and the filtrate is colorless and transparent.

[0037] After washing and filtering with hot toluene, use 50 mL of acetone to filter and wash several times, and then continue filtering for 5 minutes.

[0038] Remove the filter, wipe the outside of the filter with filter paper, place the filter together with the diatomaceous earth and insoluble matter in a drying oven at 115-120°C and dry for 90 minutes, then take out, cool slightly, place in a desiccator for 30 minutes, cool to room temperature, and weigh to constant weight, accurate to 0.0001g.

[0039] Boil the used glass sand core filter crucible in 1+1 hydrochloric acid for about 20 minutes, rinse it with distilled water, dry it in a drying oven at 105~110℃ to constant weight, and store it in a desiccator for future use.

[0040] The allowable deviation should be determined based on specific product standards and test conditions.

[0041] The mass fraction of quinoline insoluble matter is calculated as follows:

[0042] Where: W is the mass fraction of quinoline insoluble matter; G2 is the total mass of the filter (glass crucible), diatomaceous earth and quinoline insolubles, in g; G1 is the mass of the filter (glass sand core crucible) and diatomaceous earth, in g; G is the mass of the sample in g.

[0043] The present invention provides a method for determining the content of quinoline insoluble matter in coal tar pitch, and the specific process is as follows: The coal tar pitch sample was dissolved with quinoline, then filtered, and the residue was washed with hot quinoline and anhydrous ethanol in turn and filtered again, and the mass fraction of quinoline insoluble matter in coal tar pitch was calculated by drying and weighing. Wherein, a mixture of calcium carbonate and diatomaceous earth is used as a filter aid in both suction filtration and re-filtration, and the mass ratio of calcium carbonate to diatomaceous earth is 6: (4~4.5).

[0044] Preferably, the mass ratio of calcium carbonate to diatomaceous earth is 6:4. 40-60 mesh calcium carbonate and diatomaceous earth are mixed evenly in a ratio of (6:4) as a filter aid, and after analysis, they are soaked and cleaned with a hydrochloric acid solution, which can quickly remove the filter aid in the crucible without affecting the filtering performance. It can also increase the utilization rate of the glass sand core crucible, and can quickly clean the used crucible without affecting the filtering performance.

[0045] In one embodiment, a method for determining the content of quinoline insoluble matter in coal tar pitch has the following specific steps: Step 1: Dry the solid coal tar sample and grind it into particles that pass the SSω500 / 315μm sieve with a mortar. For liquid asphalt, melt the sample and stir it evenly.

[0046] Step 2: Add 2g~3g of the dry mixture of calcium carbonate and diatomaceous earth to a clean and dry G4 glass sand core filter crucible with a diameter of 40 mm, add about 2 / 3 of pure water and stir for 15s, place the G4 glass sand core filter crucible on a suction filtration bottle, filter, and allow the filter aid to be evenly spread on the bottom of the crucible. Fill the G4 glass sand core filter crucible with pure water again, filter, wipe the outer wall of the crucible dry, put it in a 115℃~120℃ oven to dry for 2h, take it out and put it in a dryer for 30min, weigh it, put it in the oven for 30min, take it out and put it in the dryer for 30min, until the difference between the two masses is ≤0.001g.

[0047] Step 3: Accurately weigh a certain amount of sample (accurate to 0.0002g) and place it in a clean and dry 250mL beaker, add 25mL of quinoline, and stir evenly with a glass rod.

[0048] In the specific implementation process, the sampling amount (weighing amount) of the coal tar pitch sample is as follows: When the quinoline insoluble content is ≤0.5%, the coal tar sampling amount is 15g; When the quinoline insoluble content is 0.5% to 1.0%, the coal tar sampling amount is 10g; When the quinoline insoluble content is 1.0% to 2.0%, the coal tar sampling amount is 5g; When the quinoline insoluble content is 2.0% to 5.0%, the coal tar sampling amount is 2g; When the quinoline insoluble content is ≥5.0%, the coal tar sampling amount is 1g.

[0049] Step 4: Immerse the beaker containing the sample in a constant temperature water bath at (75±5)℃ and stir the sample from time to time within 30 minutes.

[0050] Step 5: Install the clean and dried G4 glass sand core filter crucible to constant weight on the filter bottle, and soak the filter aid in the sand core crucible with a small amount of quinoline. Slowly pour the dissolved sample into the filter (G4 glass sand core filter crucible as the filter) and filter at the same time.

[0051] Step 6: Wash the beaker several times with 30 mL of hot quinoline to transfer all the residues to the sand core crucible, then wash the residues in the filter several times with 30 mL of hot quinoline and filter at the same time. The temperature of the hot quinoline should be maintained during filtration.

[0052] Step 7: After washing with hot quinoline and filtering, filter and wash with 30 mL to 100 mL, preferably about 50 mL, of anhydrous ethanol for several times. The number of times of washing with anhydrous ethanol is at least 3 times, and the amount of anhydrous ethanol used for each washing is 10 to 30 mL. Wash until the filtrate is colorless and transparent, and then continue filtering for 5 minutes.

[0053] Step 8: Remove the G4 glass sand core filter crucible, wipe the outside of the sand core crucible with filter paper, place the sand core crucible in an oven at 115℃~120℃ and dry it for 90 minutes, then take it out, cool it slightly, place it in a desiccator for 30 minutes, and weigh it to constant weight, accurate to 0.0001g.

[0054] Step 9: Boil the used glass crucible in 1+1 hydrochloric acid for about 20 minutes, rinse it with pure water, dry it in a dryer at 105℃~110℃ to constant weight, and store it in a dryer for later use.

[0055] Calculate the mass fraction of quinoline insoluble matter according to the weighing results. The formula is:

[0056] Where: W is the mass fraction of quinoline insoluble matter; G2' is the total mass of the filter (glass sand core crucible), filter aid and quinoline insoluble matter, in g; G1 is the mass of the filter (glass sand core crucible) and filter aid, in g; G is the mass of the sample in g.

[0057] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0058] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0059] Comparative Example 1. Accurately weigh about 2g of the sample (accurate to 0.0002g) and place it in a clean and dry 250mL beaker, add 25mL of quinoline, and stir evenly with a glass rod.

[0060] 2. Immerse the beaker containing the sample in a constant temperature water bath at (75±5)℃ and stir the sample from time to time within 30 minutes.

[0061] 3. Install the clean and dried G4 glass sand core filter crucible to constant weight on the suction filtration bottle, and soak the diatomaceous earth in the sand core crucible with a small amount of quinoline. Slowly pour the dissolved sample into the filter (G4 glass sand core filter crucible as the filter) and filter at the same time.

[0062] 4. Wash the beaker with 30 mL of hot quinoline three times (about 10 mL each time) to transfer all the residues to the sand core crucible, then wash the residues in the filter with 30 mL of hot quinoline three times (about 10 mL each time) and filter at the same time. The temperature of the hot quinoline should be maintained during filtration.

[0063] 5. After washing with hot quinoline and filtering, use about 100 mL of hot toluene to filter and wash 7 to 8 times until the filtrate becomes colorless and transparent.

[0064] 6. Wash the sand core crucible with hot toluene, then filter and wash it several times with 50 mL of acetone, and then continue to filter for 5 minutes.

[0065] 7. Remove the G4 glass sand core filter crucible, wipe the outside of the sand core crucible with filter paper, place the sand core crucible in an oven at 115℃~120℃ and dry it for 90 minutes, then take it out, cool it slightly, place it in a dryer for 30 minutes, and weigh it to constant weight, accurate to 0.0001g.

[0066] Two sets of parallel samples were used for analysis and testing, and the analytical data were 2.24% and 2.22% respectively.

[0067] Comparative Example 1. Accurately weigh about 1g of the sample (accurate to 0.0002g) and place it in a clean and dry 250mL beaker, add 25mL of quinoline, and stir evenly with a glass rod.

[0068] 2. Immerse the beaker containing the sample in a constant temperature water bath at (75±5)℃ and stir the sample from time to time within 30 minutes.

[0069] 3. Install the clean and dried G4 glass sand core filter crucible to constant weight on the suction filtration bottle, and soak the filter aid in the sand core crucible with a small amount of quinoline. Slowly pour the dissolved sample into the filter (G4 glass sand core filter crucible as the filter) and filter at the same time. The mass ratio of calcium carbonate to diatomaceous earth in the filter aid is 6:5.

[0070] 4. Wash the beaker with 30 mL of hot quinoline three times (about 10 mL each time) to transfer all the residues to the sand core crucible, then wash the residues in the filter with 30 mL of hot quinoline three times (about 10 mL each time) and filter at the same time. The temperature of the hot quinoline should be maintained during filtration.

[0071] 5. Wash the hot quinoline and filter it. Then use about 50 mL of anhydrous ethanol to filter and wash it three times (about 15 mL each time) until the filtrate is colorless and transparent. Then continue to filter for 5 minutes.

[0072] Two sets of parallel samples were used for analysis and testing, and the analytical data were 1.92% and 1.95% respectively.

[0073] Comparative Example 1. Accurately weigh about 1g of the sample (accurate to 0.0002g) and place it in a clean and dry 250mL beaker, add 25mL of quinoline, and stir evenly with a glass rod.

[0074] 2. Immerse the beaker containing the sample in a constant temperature water bath at (75±5)℃ and stir the sample from time to time within 30 minutes.

[0075] 3. Install the clean and dried G4 glass sand core filter crucible to constant weight on the suction filtration bottle, and soak the filter aid in the sand core crucible with a small amount of quinoline. Slowly pour the dissolved sample into the filter (G4 glass sand core filter crucible as the filter) and filter at the same time. The mass ratio of calcium carbonate to diatomaceous earth in the filter aid is 6:3.5.

[0076] 4. Wash the beaker with 30 mL of hot quinoline three times (about 10 mL each time) to transfer all the residues to the sand core crucible, then wash the residues in the filter with 30 mL of hot quinoline three times (about 10 mL each time) and filter at the same time. The temperature of the hot quinoline should be maintained during filtration.

[0077] 5. Wash the hot quinoline and filter it. Then use about 50 mL of anhydrous ethanol to filter and wash it three times (about 15 mL each time) until the filtrate is colorless and transparent. Then continue to filter for 5 minutes.

[0078] Two sets of parallel samples were used for analysis and testing, and the analytical data were 1.92% and 1.97% respectively.

[0079] Example 1 1. Accurately weigh about 1g of the sample (accurate to 0.0002g) and place it in a clean and dry 250mL beaker, add 25mL of quinoline, and stir evenly with a glass rod.

[0080] 2. Immerse the beaker containing the sample in a constant temperature water bath at (75±5)℃ and stir the sample from time to time within 30 minutes.

[0081] 3. Install the clean and dried G4 glass sand core filter crucible to constant weight on the suction filtration bottle, and soak the filter aid in the sand core crucible with a small amount of quinoline. Slowly pour the dissolved sample into the filter (G4 glass sand core filter crucible as the filter) and filter at the same time. The mass ratio of calcium carbonate to diatomaceous earth in the filter aid is 6:4.5.

[0082] 4. Wash the beaker with 30 mL of hot quinoline three times (about 10 mL each time) to transfer all the residues to the sand core crucible, then wash the residues in the filter with 30 mL of hot quinoline three times (about 10 mL each time) and filter at the same time. The temperature of the hot quinoline should be maintained during filtration.

[0083] 5. Wash the hot quinoline and filter it. Then use about 50 mL of anhydrous ethanol to filter and wash it three times (about 15 mL each time) until the filtrate is colorless and transparent. Then continue to filter for 5 minutes.

[0084] Two sets of parallel samples were used for analysis and testing, and the analytical data were 2.08% and 2.07% respectively.

[0085] Example 2 1. Accurately weigh about 2g of the sample (accurate to 0.0002g) and place it in a clean and dry 250mL beaker, add 25mL of quinoline, and stir evenly with a glass rod.

[0086] 2. Immerse the beaker containing the sample in a constant temperature water bath at (75±5)℃ and stir the sample from time to time within 30 minutes.

[0087] 3. Install the clean and dried G4 glass sand core filter crucible to constant weight on the suction filtration bottle, and soak the filter aid in the sand core crucible with a small amount of quinoline. Slowly pour the dissolved sample into the filter (G4 glass sand core filter crucible as the filter) and filter at the same time. The mass ratio of calcium carbonate to diatomaceous earth in the filter aid is 6:4.

[0088] 4. Wash the beaker with 30 mL of hot quinoline three times (about 10 mL each time) to transfer all the residues to the sand core crucible, then wash the residues in the filter with 30 mL of hot quinoline three times (about 10 mL each time) and filter at the same time. The temperature of the hot quinoline should be maintained during filtration.

[0089] 5. Wash the hot quinoline and filter it. Then use about 50 mL of anhydrous ethanol to filter and wash it three times (about 15 mL each time) until the filtrate is colorless and transparent. Then continue to filter for 5 minutes.

[0090] Two sets of parallel samples were used for analysis and testing, and the analytical data were 2.22% and 2.21% respectively.

[0091] Example 3 Except for the following contents, the rest is the same as Example 2.

[0092] Accurately weigh about 5g of the sample (accurate to 0.0002g) and place it in a clean and dry 250mL beaker, add 25mL of quinoline, and stir evenly with a glass rod.

[0093] Two sets of parallel samples were used for analysis and testing, and the analytical data were 2.22% and 2.20% respectively.

[0094] Example 4 Except for the following contents, the rest is the same as Example 3.

[0095] Accurately weigh about 10g of the sample (accurate to 0.0002g) and place it in a clean and dry 250mL beaker, add 25mL of quinoline, and stir evenly with a glass rod.

[0096] Two sets of parallel samples were used for analysis and testing, and the analytical data were 2.22% and 2.24% respectively.

[0097] Example 5 Except for the following contents, the rest is the same as Example 2.

[0098] Accurately weigh about 2g of the sample (accurate to 0.0002g) and place it in a clean and dry 250mL beaker. Add 50mL of quinoline and stir evenly with a glass rod.

[0099] Two sets of parallel samples were used for analysis and testing, and the analytical data were 2.21% and 2.22% respectively.

[0100] Example 6 Except for the following contents, the rest is the same as Example 5.

[0101] Accurately weigh about 2g of the sample (accurate to 0.0002g) and place it in a clean and dry 250mL beaker, add 100mL of quinoline, and stir evenly with a glass rod.

[0102] Two sets of parallel samples were used for analysis and testing, and the analytical data were 2.23% and 2.21% respectively.

[0103] Example 7 Except for the following contents, the rest is the same as Example 2.

[0104] After washing with hot quinoline and filtering, use 30 mL of anhydrous ethanol three times (about 10 mL each time) to filter and wash until the filtrate is colorless and transparent. Then continue filtering for 5 minutes.

[0105] Two sets of parallel samples were used for analysis and testing, and the analytical data were 2.35% and 2.33% respectively.

[0106] Example 8 Except for the following contents, the rest is the same as Example 2.

[0107] After washing with hot quinoline and filtering, use about 100 mL of anhydrous ethanol to filter and wash three times (about 30 mL each time) until the filtrate is colorless and transparent. Then continue filtering for 5 minutes.

[0108] Two sets of parallel samples were used for analysis and testing, and the analytical data were 2.22% and 2.20% respectively.

[0109] In the prior art, when washing the residue, hot quinoline, hot toluene and acetone are used in sequence, while the present invention uses anhydrous ethanol to replace toluene and acetone. Anhydrous ethanol, as a relatively environmentally friendly solvent, has relatively low toxicity and volatility, and is less harmful to the environment and human body. In addition, the use of anhydrous ethanol simplifies the test steps, making the test simpler and shortening the analysis time. The above-mentioned determination method can improve the determination speed and efficiency and can improve the filtering effect. Anhydrous ethanol is used as a washing solvent, which reduces the number of washing times and time and improves the determination efficiency. The safety problem of using two highly toxic chemicals, toluene and acetone, as washing solvents and the technical problem of long analysis time caused by using two washing solvents for washing are solved.

[0110] The mixed use of calcium carbonate and diatomaceous earth optimizes the performance of the filter aid and makes the filtration process faster. The porous structure of diatomaceous earth provides a large amount of filtration area, and the addition of calcium carbonate further enhances the filtration capacity of the filter aid and reduces the time required for filtration. The use of mixed filter aids makes the filter cake looser and easier to wash and filter, reduces the compressibility and clogging of the filter cake, and improves the filtration effect and data repeatability. Moreover, compared with using only diatomaceous earth as a filter aid, the addition of calcium carbonate reduces the risk of diatomaceous earth clogging and improves the measurement effect and speed.

[0111] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for determining the content of quinoline insoluble matter in coal tar pitch, characterized in that: The following steps are involved: The coal tar pitch sample was dissolved with quinoline, then filtered, and the residue was washed with hot quinoline and anhydrous ethanol in turn and filtered again, and the mass fraction of quinoline insoluble matter in coal tar pitch was calculated by drying and weighing. Wherein, a mixture of calcium carbonate and diatomaceous earth is used as a filter aid in both suction filtration and re-filtration, and the mass ratio of calcium carbonate to diatomaceous earth is 6: (4~4.5).

2. The method for determining the content of quinoline insoluble matter in coal tar pitch according to claim 1, wherein: The process of using quinoline to dissolve the coal tar pitch sample is as follows: Place the quinoline and coal tar samples in a constant temperature water bath at 75±5°C and continue stirring for 30 min to complete dissolution.

3. The method for determining the content of quinoline insoluble matter in coal tar pitch according to claim 1, characterized in that: The temperature of the hot quinoline is 75±5°C.

4. The method for determining the content of quinoline insoluble matter in coal tar pitch according to claim 1, characterized in that: The total amount of anhydrous ethanol used for washing is 30 mL to 100 mL.

5. The method for determining the content of quinoline insoluble matter in coal tar pitch according to claim 1 or 4, characterized in that: The washing times of the anhydrous ethanol are at least 3 times, and the amount of the anhydrous ethanol used for each washing is 10-30 mL.

6. The method for determining the content of quinoline insoluble matter in coal tar pitch according to claim 1, characterized in that: The washing with anhydrous ethanol is terminated when the filtrate becomes colorless and transparent.

7. The method for determining the content of quinoline insoluble matter in coal tar pitch according to claim 1, characterized in that: The time for the second filtration is 5 min.

8. The method for determining the content of quinoline insoluble matter in coal tar pitch according to claim 1, characterized in that: The drying temperature is 115-120° C., and the drying time is 90 min.

9. The method for determining the content of quinoline insoluble matter in coal tar pitch according to claim 1, characterized in that: The particle size range of the calcium carbonate is 40 mesh to 60 mesh.

10. The method for determining the content of quinoline insoluble matter in coal tar pitch according to claim 1, characterized in that: The mass fraction of coal tar quinoline insoluble matter is the ratio of the difference between the total mass of the filter, the filter aid and the coal tar quinoline insoluble matter and the mass of the filter and the filter aid to the mass of the coal tar sample.

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