Method for measuring high and low calorific values of blast furnace fly ash

Abstract

The invention discloses a method for measuring high and low calorimetric values of blast furnace fly ash, which relates to the technical field of blast furnace fly ash calorimetric values, and comprises the following specific steps: step 1, calibrating the thermal capacity of a calorimeter, continuously measuring a plurality of groups of thermal capacity data, and carrying out average value calculation to obtain the average thermal capacity data of the calorimeter to finish calibration; 2, measuring as received basis moisture of the sample; 3, measuring the air dry basis moisture of the sample; 4, measuring the air dry basis total sulfur content of the sample; 5, measuring the air dry basis hydrogen content of the sample; 6, measuring the cylinder calorific value of the sample; and 7, calculating high and low calorific values. According to the method, a rapid calorimeter is adopted as a detection instrument, a blast furnace dedusting ash sample is put into a sealed oxygen bomb filled with high-pressure pure oxygen to be burnt, the calorific value of a bomb cylinder is obtained, the moisture, total sulfur and hydrogen content of the bomb cylinder are measured and brought into a calorimeter testing system to be calculated, and therefore the high and low calorific values of the blast furnace dedusting ash are measured.

Description

Technical Field

[0001] The invention relates to the technical field of calorific value of blast furnace dust ash, and in particular to a method for determining high and low calorific values ​​of blast furnace dust ash. Background Art

[0002] Blast furnace dust is generated during the smelting process of the blast furnace and collected by the gravity dust collector. Its main components are iron, residual coal powder, silicon dioxide, calcium oxide and other alkali metal elements. Blast furnace dust can be used as sintering raw materials for sintering, or it can be mixed with coal powder in a certain proportion and sprayed into the blast furnace to improve the combustion performance of coal powder and the air permeability of the lower part of the blast furnace, which is conducive to reducing fuel usage and production energy consumption, so it has a high recycling value.

[0003] The high and low calorific values ​​of blast furnace dust ash are important production detection indicators. They can directly reflect the amount of coal powder remaining in the blast furnace dust ash sample, thereby judging whether the combustion is sufficient during blast furnace smelting, and can also provide data reference for the recycling of blast furnace dust ash. However, the mass proportion of residual coal powder in blast furnace dust ash is usually only 5% to 30%, and the rest is a large amount of non-combustible substances. As a result, when using conventional calorific value detection methods to detect blast furnace dust ash, there will be cases where the sample is not fully burned or even cannot be ignited, making it difficult to accurately determine its calorific value.

[0004] Prior art CN1114894841A discloses a method for detecting the calorific value of carbon-containing dust ash using a certified coal standard sample and acid-washed asbestos after high-temperature burning as auxiliary fuel. This method uses a small amount of acid-washed asbestos after high-temperature burning to pad the bottom of the oxygen bomb crucible, and then layers and lays the coal standard sample and carbon-containing dust ash in turn, solving the technical problem of insufficient combustion and difficulty in ignition of the carbon-containing dust ash sample. However, the invention method has certain shortcomings. First, the coal standard sample used is easy to absorb water and deteriorate, so the combustion calorific value of the standard coal sample must be measured before each detection of the carbon-containing dust ash sample, which increases the detection cycle; second, the detected indicator is the bomb calorific value, and the influence of the moisture, total sulfur and hydrogen content in the sample on the calorific value is not considered, and a more reference high and low calorific value is not obtained. There is still room for improvement. For this reason, we propose a method for determining the high and low calorific values ​​of blast furnace dust ash. Summary of the invention

[0005] The object of the present invention is to provide a method for determining the high and low calorific values ​​of blast furnace dust ash. By using a rapid calorimeter as a detection instrument, a blast furnace dust ash sample is placed in a sealed oxygen bomb filled with high-pressure pure oxygen and burned to obtain the bomb calorific value, and its moisture, total sulfur and hydrogen contents are determined and brought into the calorimeter test system for calculation, thereby determining the high and low calorific values ​​of the blast furnace dust ash.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for determining the high and low calorific values ​​of blast furnace dust, comprising the following specific steps: Step 1: Calibrate the heat capacity of the calorimeter Control the test environment temperature and humidity, turn on the calorimeter to preheat the instrument, change the measurement mode of the test system to benzoic acid standard heat capacity, and enter the calorific value of the fusible ignition wire used and the certified value of the calorific value standard sample of benzoic acid into the corresponding positions; Place the benzoic acid calorific value standard sample in a constant temperature forced air drying oven for drying, weigh the dried benzoic acid calorific value standard sample and place it in a nickel-chromium combustion dish, then place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, and connect the two ends to the electrode column of the oxygen bomb; Add distilled water to the oxygen bomb, install the crucible stand, keep the amount of distilled water added each time constant, slowly fill the oxygen bomb with industrial oxygen until the pressure reaches the set pressure, continue to oxygenate for a while after reaching the pressure, put the oxygen bomb into the inner cylinder of the calorimeter, measure the calorific value of benzoic acid standard sample, and obtain the instrument heat capacity data; Repeat the above steps to continuously measure multiple groups of heat capacity data, and select some groups of heat capacity data to calculate the average value, obtain the average heat capacity data of the instrument, and complete the calibration; Step 2: Determine the received basic moisture content of the sample Weigh the blast furnace dust sample and spread it flat in a shallow dish of known mass. Put the shallow dish with the sample into a constant temperature blast drying oven preheated to a certain temperature and dry it. Take out the shallow dish, cool it at room temperature for a period of time and weigh it. Record the total mass of the shallow dish and the sample after drying, and calculate the as-received moisture content of the sample. Step 3: Determine the air-dried moisture content of the sample Weigh the analysis sample and place it flat in a flat weighing bottle after drying, and put it into a constant temperature blast drying oven preheated to a certain temperature. After drying for a period of time, take out the weighing bottle, cool it for a period of time at room temperature, and weigh it. Record the total mass of the flat weighing bottle and the analysis sample after drying, and calculate the air-dried basis moisture content of the analysis sample. Step 4: Determine the total sulfur content of the sample on an air-dried basis A high-frequency infrared carbon-sulfur analyzer was used as the detection instrument, and a certified standard sample of dust ash with a matrix composition and content close to that of blast furnace dust ash was selected to establish a total sulfur analysis curve. Start the high-frequency infrared carbon-sulfur analyzer, ensure that the instrument status meets the detection requirements, calibrate the analysis curve, weigh pure iron particles and spread them on the bottom of the special crucible for carbon-sulfur analysis, then weigh the blast furnace dust ash analysis sample and place it on the pure iron particles, and cover the analysis sample with tungsten-tin flux particles, put the crucible containing the analysis sample on the instrument crucible drag, start the detection program, and heat the analysis sample in the oxygen flow of the high-frequency induction furnace to decompose. The sulfur enters the infrared cell for detection in the form of sulfur dioxide to obtain the air-dried total sulfur content of the analysis sample; Step 5: Determine the air-dried hydrogen content of the sample Using CHN element analyzer as the detection instrument, due to the lack of dust ash standard samples containing hydrogen certification value, the method uses the certified coal standard samples with hydrogen content close to that of blast furnace dust ash to establish the hydrogen analysis curve; Turn on the CHN element analyzer, start the heating program, preheat the instrument after it has finished heating up, perform a system leak check to ensure that the instrument is in a stable state, and before measuring the sample, perform multiple sets of blank analysis until the instrument reaches a balanced state, then add multiple sets of "waste samples" for preheating tests, and then measure the certified coal standard sample to perform drift correction on the instrument; Use a tin paper cup to weigh the blast furnace dust analysis sample, fully burn it in a high-purity oxygen flow, and the hydrogen reaction generates water that enters the infrared cell for detection to obtain the air-dried hydrogen content of the analysis sample; Step 6: Determine the calorific value of the sample Start the calorimeter, set the measurement mode of the test system to calorific value, and perform multiple sets of preheating tests before testing and analyzing the samples to ensure the stability of the instrument; Grind the dried benzoic acid calorific value standard sample into powder as an additive, burn the pickled asbestos in a muffle furnace, weigh the benzoic acid powder and the blast furnace dust ash analysis sample and mix them evenly, input the mass of the benzoic acid powder and the analysis sample in the test interface respectively, weigh the pickled asbestos after high temperature burning and lay it flat on the bottom of the nickel-chromium combustion dish, then place the mixed sample on the pickled asbestos, gently tap the nickel-chromium combustion dish to make the mixed sample in a vibrated state, then place the nickel-chromium combustion dish on the oxygen bomb crucible rack, take a section of fusible ignition wire, and connect both ends to the oxygen bomb electrode column; Add distilled water to the oxygen bomb, install the crucible stand, keep the amount of distilled water added consistent with that during heat capacity calibration, slowly fill the oxygen bomb with industrial oxygen until the pressure reaches the set pressure, continue to fill with oxygen for a period of time after reaching the pressure, put the oxygen bomb into the inner cylinder of the calorimeter, and measure the mixed sample. After the measurement, the analysis system will automatically subtract the theoretical calorific value of benzoic acid from the calorific value of the mixed sample to obtain the calorific value of the blast furnace dust sample; And the calorific value of blast furnace dust removal ash cartridge can be calculated by the calculation formula of blast furnace dust removal ash cartridge calorific value; Step 7: Calculate high and low calorific values When the calorific value of the blast furnace dust ash cartridge is determined, the data of the received basis moisture, air dried basis moisture, air dried basis total sulfur and air dried basis hydrogen detected in the above steps are filled into the corresponding positions in the calorific value calculation program in turn to calculate the high and low calorific values ​​of the blast furnace dust ash.

[0007] Preferably, the specific method for calibrating the heat capacity of the calorimeter in step 1 is as follows: Control the test environment temperature to 24-26℃ and the humidity to 40%-85%. Turn on the calorimeter to preheat the instrument to ensure that the instrument status meets the test requirements. Change the measurement mode of the test system to benzoic acid standard heat capacity. Enter the calorific value of the fusible ignition wire used and the certified value of the benzoic acid calorific value standard sample into the corresponding positions. The calorific value of the ignition wire is 25-50J, and the certified value of the benzoic acid calorific value standard sample is 26.465-26.470MJ / kg. Place the benzoic acid calorific value standard sample in a constant temperature forced air drying oven at 60-70℃ for 3-4h, weigh 1.0-1.5g of the dried benzoic acid calorific value standard sample and place it in a nickel-chromium combustion dish, then place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, and connect the two ends to the electrode column of the oxygen bomb; Add 5-10 mL of distilled water to the oxygen bomb, install the crucible stand, and carefully tighten the oxygen bomb cover. The amount of distilled water added each time must be kept constant. Slowly fill the oxygen bomb with industrial oxygen with a purity of ≥99.5% until the pressure reaches 2.8-3.0 MPa. After reaching the pressure, continue to oxygenate for 15-20S. Do not use electrolytic oxygen. Place the oxygen bomb in the inner cylinder of the calorimeter, measure the calorific value of the benzoic acid standard sample, and obtain the instrument's heat capacity data.

[0008] Preferably, the specific method for determining the received basic moisture content of the sample in step 2 is as follows: Weigh 490-510g of blast furnace dust sample and spread it evenly in a shallow dish of known mass. Place the shallow dish with the sample in a constant temperature forced air drying oven preheated to 105-110°C and dry for 1.5-2.0h. Take out the shallow dish and cool it at room temperature for 5-10min. Weigh it and record the total mass of the shallow dish and sample after drying. Calculate the as-received moisture content of the sample.

[0009] Preferably, the specific method for determining the air-dried basis moisture of the sample in step 3 is as follows: Weigh about 1.0 g of the analytical sample and spread it flat in a flat weighing bottle after drying. Open the bottle cap and put it into a constant temperature forced air drying oven preheated to 105-110°C for drying for 1.5-2.0 hours. Cover the bottle cap, take out the weighing bottle, cool it at room temperature for 5-10 minutes, weigh it, record the total mass of the flat weighing bottle and the analytical sample after drying, and calculate the air-dried basis moisture content of the analytical sample.

[0010] Preferably, the specific method for determining the air-dried total sulfur content of the sample in step 4 is as follows: A high-frequency infrared carbon-sulfur analyzer was used as the detection instrument, and a certified standard sample of dust ash with a matrix composition and content close to that of blast furnace dust ash was selected to establish a total sulfur analysis curve. Start the high-frequency infrared carbon-sulfur analyzer, ensure that the instrument status meets the detection requirements, calibrate the analysis curve, weigh 0.4-0.5g of pure iron particles and spread them on the bottom of the special crucible for carbon-sulfur analysis, then weigh 0.05-0.1g of blast furnace dust ash analysis sample and place it on the pure iron particles, and cover the analysis sample with 1.5-2.0g of tungsten-tin flux particles, put the crucible with the analysis sample on the instrument crucible drag, start the detection program, heat and decompose the analysis sample in the oxygen flow of the high-frequency induction furnace, and the sulfur enters the infrared cell for detection in the form of sulfur dioxide to obtain the air-dried total sulfur content of the analysis sample.

[0011] Preferably, the specific method for determining the air-dried hydrogen content of the sample in step 5 is as follows: Using CHN element analyzer as the detection instrument, due to the lack of dust ash standard samples containing hydrogen certification value, the method uses the certified coal standard samples with hydrogen content close to that of blast furnace dust ash to establish the hydrogen analysis curve; Turn on the CHN element analyzer and start the heating program. After the instrument is heated up, preheat it for 1 to 2 hours. Perform a system leak check to ensure that the instrument is stable. Before measuring the sample, perform 3 to 5 sets of blank analysis until the instrument reaches a balanced state. Then add 2 to 3 sets of "waste samples" for preheating test. After that, measure the certified coal standard sample to calibrate the instrument for drift. Use a tin paper cup to weigh about 80 mg of blast furnace dust analysis sample, fully burn it in a high-purity oxygen flow, and the hydrogen reaction generates water that enters the infrared cell for detection to obtain the air-dried hydrogen content of the analysis sample.

[0012] Preferably, the specific method for determining the calorific value of the cartridge of the sample in step 6 is as follows: Start the calorimeter, set the measurement mode of the test system to calorific value, and perform 3 to 5 sets of preheating tests before testing and analyzing the samples to ensure that the instrument is in a stable state; Grind the dried benzoic acid calorific value standard sample into powder with a particle size of ≤0.2mm as an additive, burn the pickled asbestos in a muffle furnace at a furnace temperature of 750-850℃ for 0.5-1h, accurately weigh 0.05-0.3g of benzoic acid powder and 0.7-1.0g of blast furnace dust analysis sample and mix them evenly, enter the mass of benzoic acid powder and analysis sample in the test interface respectively, weigh 0.1-0.2g of pickled asbestos burned at high temperature and lay it flat on the bottom of the nickel-chromium combustion dish, then place the mixed sample on the pickled asbestos, gently tap the nickel-chromium combustion dish to make the mixed sample in a vibrated state, then place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, and connect the two ends to the electrode column of the oxygen bomb, Add 5-10mL of distilled water to the oxygen bomb, install the crucible stand, and carefully tighten the oxygen bomb cover. The amount of distilled water added should be consistent with that during the heat capacity calibration. Slowly fill the oxygen bomb with industrial oxygen with a purity of ≥99.5% until the pressure reaches 2.8-3.0MPa. Continue to fill the oxygen for 15-20S after reaching the pressure. Do not use electrolytic oxygen. Put the oxygen bomb into the inner cylinder of the calorimeter and measure the mixed sample. After the measurement, the analysis system will automatically subtract the theoretical calorific value of benzoic acid from the calorific value of the mixed sample to obtain the calorific value of the blast furnace dust sample; And the calorific value of blast furnace dust removal ash cartridge can be calculated by the calculation formula of the calorific value of blast furnace dust removal ash cartridge.

[0013] Preferably, the calculation formula for the calorific value of the blast furnace dust ash cartridge is: Where: Q 1 is the calorific value of the blast furnace dust, in MJ / kg; Q 2 is the calorific value of benzoic acid, in MJ / kg; Q 3 is the measured barrel calorific value of the mixed sample, in MJ / kg; m 1 is the mass of blast furnace dust, in g; m 2 is the mass of benzoic acid powder, in g.

[0014] Preferably, in step one and step six, the two ends are connected to the oxygen bomb electrode column, and the bent ignition wire maintains good contact with the sample.

[0015] Preferably, the specific method for calibrating the heat capacity of the calorimeter in step 1 also includes the following method: Repeat the above steps to continuously measure 6 to 8 groups of heat capacity data, and select 5 groups of heat capacity data with relative standard deviation ≤ 0.2% to calculate the average value, obtain the average heat capacity data of the instrument, and complete the calibration.

[0016] Technical effects and advantages of the present invention: (1) The calorific value of blast furnace dust ash measured is not limited to a single bomb calorific value, but also fully refers to the influence of moisture, total sulfur and hydrogen content in the sample on the calorific value. By entering the as-received basis moisture, air-dried basis moisture, air-dried basis total sulfur and air-dried basis hydrogen, the high and low calorific values ​​of blast furnace dust ash are calculated, providing more effective data reference for the combustion of coal powder during blast furnace smelting and the recycling of blast furnace dust ash; (2) The blast furnace dust contains less residual coal powder, and the rest is a large amount of incombustibles. Therefore, when measuring the calorific value, the sample will not burn completely or even be extremely difficult to ignite. In this method, benzoic acid powder is used as an auxiliary fuel to improve the flammability of the sample, which solves this technical problem in a targeted manner. (3) Benzoic acid powder burns extremely violently under oxygen-rich conditions. When it is used as an auxiliary fuel, adding too much or treating the sample in layers will cause the blast furnace dust to splash due to the explosion of benzoic acid. This method treats the sample by mixing a small amount of benzoic acid powder with the blast furnace dust sample evenly, so that the sample can burn smoothly; (4) Benzoic acid is stable in nature. Using it instead of certified coal standard samples as auxiliary fuel can avoid the auxiliary fuel absorbing water and deteriorating, thereby ensuring the accuracy of the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the test process of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The present invention provides Figure 1 A method for determining the high and low calorific values ​​of blast furnace dust ash shown in the figure comprises the following specific steps: Step 1: Calibrate the heat capacity of the calorimeter Control the test environment temperature and humidity, turn on the calorimeter to preheat the instrument, change the measurement mode of the test system to benzoic acid standard heat capacity, and enter the calorific value of the fusible ignition wire used and the certified value of the calorific value standard sample of benzoic acid into the corresponding positions; Place the benzoic acid calorific value standard sample in a constant temperature forced air drying oven for drying, weigh the dried benzoic acid calorific value standard sample and place it in a nickel-chromium combustion dish, then place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, and connect the two ends to the electrode column of the oxygen bomb; Add distilled water to the oxygen bomb, install the crucible stand, keep the amount of distilled water added each time constant, slowly fill the oxygen bomb with industrial oxygen until the pressure reaches the set pressure, continue to oxygenate for a while after reaching the pressure, put the oxygen bomb into the inner cylinder of the calorimeter, measure the calorific value of benzoic acid standard sample, and obtain the instrument heat capacity data; Repeat the above steps to continuously measure multiple groups of heat capacity data, and select some groups of heat capacity data to calculate the average value, obtain the average heat capacity data of the instrument, and complete the calibration; Step 2: Determine the sample's received basic moisture content Weigh the blast furnace dust sample and spread it flat in a shallow dish of known mass. Put the shallow dish with the sample into a constant temperature blast drying oven preheated to a certain temperature and dry it. Take out the shallow dish, cool it at room temperature for a period of time and weigh it. Record the total mass of the shallow dish and the sample after drying, and calculate the as-received moisture content of the sample. Step 3: Determine the air-dried moisture content of the sample Weigh the analysis sample and place it flat in a flat weighing bottle after drying, and put it into a constant temperature blast drying oven preheated to a certain temperature. After drying for a period of time, take out the weighing bottle, cool it for a period of time at room temperature, and weigh it. Record the total mass of the flat weighing bottle and the analysis sample after drying, and calculate the air-dried basis moisture content of the analysis sample. Step 4: Determine the total sulfur content of the sample on an air-dried basis A high-frequency infrared carbon-sulfur analyzer was used as the detection instrument, and a certified standard sample of dust ash with a matrix composition and content close to that of blast furnace dust ash was selected to establish a total sulfur analysis curve. Start the high-frequency infrared carbon-sulfur analyzer, ensure that the instrument status meets the detection requirements, calibrate the analysis curve, weigh pure iron particles and spread them on the bottom of the special crucible for carbon-sulfur analysis, then weigh the blast furnace dust ash analysis sample and place it on the pure iron particles, and cover the analysis sample with tungsten-tin flux particles, put the crucible containing the analysis sample on the instrument crucible drag, start the detection program, and heat the analysis sample in the oxygen flow of the high-frequency induction furnace to decompose. The sulfur enters the infrared cell for detection in the form of sulfur dioxide to obtain the air-dried total sulfur content of the analysis sample; Step 5: Determine the air-dried hydrogen content of the sample Using CHN element analyzer as the detection instrument, due to the lack of dust ash standard samples containing hydrogen certification value, the method uses the certified coal standard samples with hydrogen content close to that of blast furnace dust ash to establish the hydrogen analysis curve; Turn on the CHN element analyzer, start the heating program, preheat the instrument after it has finished heating up, perform a system leak check to ensure that the instrument is in a stable state, and before measuring the sample, perform multiple sets of blank analysis until the instrument reaches a balanced state, then add multiple sets of "waste samples" for preheating tests, and then measure the certified coal standard sample to perform drift correction on the instrument; Use a tin paper cup to weigh the blast furnace dust analysis sample, fully burn it in a high-purity oxygen flow, and the hydrogen reaction generates water that enters the infrared cell for detection to obtain the air-dried hydrogen content of the analysis sample; Step 6: Determine the calorific value of the sample Start the calorimeter, set the measurement mode of the test system to calorific value, and perform multiple sets of preheating tests before testing and analyzing the samples to ensure the stability of the instrument; Grind the dried benzoic acid calorific value standard sample into powder as an additive, burn the pickled asbestos in a muffle furnace, weigh the benzoic acid powder and the blast furnace dust ash analysis sample and mix them evenly, input the mass of the benzoic acid powder and the analysis sample in the test interface respectively, weigh the pickled asbestos after high temperature burning and lay it flat on the bottom of the nickel-chromium combustion dish, then place the mixed sample on the pickled asbestos, gently tap the nickel-chromium combustion dish to make the mixed sample in a vibrated state, then place the nickel-chromium combustion dish on the oxygen bomb crucible rack, take a section of fusible ignition wire, and connect both ends to the oxygen bomb electrode column; Add distilled water to the oxygen bomb, install the crucible stand, keep the amount of distilled water added consistent with that during heat capacity calibration, slowly fill the oxygen bomb with industrial oxygen until the pressure reaches the set pressure, continue to fill with oxygen for a period of time after reaching the pressure, put the oxygen bomb into the inner cylinder of the calorimeter, and measure the mixed sample. After the measurement, the analysis system will automatically subtract the theoretical calorific value of benzoic acid from the calorific value of the mixed sample to obtain the calorific value of the blast furnace dust sample; And the calorific value of blast furnace dust removal ash cartridge can be calculated by the calculation formula of blast furnace dust removal ash cartridge calorific value; Step 7: Calculate high and low calorific values When the calorific value of the blast furnace dust ash cartridge is determined, the data of the received basis moisture, air dried basis moisture, air dried basis total sulfur and air dried basis hydrogen detected in the above steps are filled into the corresponding positions in the calorific value calculation program in turn to calculate the high and low calorific values ​​of the blast furnace dust ash.

[0020] Furthermore, the specific method for calibrating the heat capacity of the calorimeter in step 1 is as follows: Control the test environment temperature to 24-26℃ and the humidity to 40%-85%. Turn on the calorimeter to preheat the instrument to ensure that the instrument status meets the test requirements. Change the measurement mode of the test system to benzoic acid standard heat capacity. Enter the calorific value of the fusible ignition wire used and the certified value of the benzoic acid calorific value standard sample into the corresponding positions. The calorific value of the ignition wire is 25-50J, and the certified value of the benzoic acid calorific value standard sample is 26.465-26.470MJ / kg. Place the benzoic acid calorific value standard sample in a constant temperature forced air drying oven at 60-70℃ for 3-4h, weigh 1.0-1.5g of the dried benzoic acid calorific value standard sample and place it in a nickel-chromium combustion dish, then place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, and connect the two ends to the electrode column of the oxygen bomb; Add 5-10mL of distilled water to the oxygen bomb, install the crucible stand, and carefully tighten the oxygen bomb cover. The amount of distilled water added each time must be kept constant. Slowly fill the oxygen bomb with industrial oxygen with a purity of ≥99.5% until the pressure reaches 2.8-3.0MPa. After reaching the pressure, continue to oxygenate for 15-20S. Do not use electrolytic oxygen. Put the oxygen bomb into the inner cylinder of the calorimeter, measure the calorific value of the benzoic acid standard sample, and obtain the instrument heat capacity data; Repeat the above steps to continuously measure 6 to 8 groups of heat capacity data, and select 5 groups of heat capacity data with relative standard deviation ≤ 0.2% to calculate the average value, obtain the average heat capacity data of the instrument, and complete the calibration.

[0021] Furthermore, the specific method for determining the received basic moisture of the sample in step 2 is as follows: Weigh 490-510g of blast furnace dust sample and spread it evenly in a shallow dish of known mass. Place the shallow dish with the sample in a constant temperature forced air drying oven preheated to 105-110°C and dry for 1.5-2.0h. Take out the shallow dish and cool it at room temperature for 5-10min. Weigh it and record the total mass of the shallow dish and sample after drying. Calculate the as-received moisture content of the sample.

[0022] It should be noted that the specific method for determining the air-dried basis moisture of the sample in step 3 is as follows: Weigh about 1.0 g of the analytical sample and spread it flat in a flat weighing bottle after drying. Open the bottle cap and put it into a constant temperature forced air drying oven preheated to 105-110°C for drying for 1.5-2.0 hours. Cover the bottle cap, take out the weighing bottle, cool it at room temperature for 5-10 minutes, weigh it, record the total mass of the flat weighing bottle and the analytical sample after drying, and calculate the air-dried basis moisture content of the analytical sample.

[0023] It should be noted that the specific method for determining the air-dried total sulfur content of the sample in step 4 is as follows: A high-frequency infrared carbon-sulfur analyzer was used as the detection instrument, and a certified standard sample of dust ash with a matrix composition and content close to that of blast furnace dust ash was selected to establish a total sulfur analysis curve. Start the high-frequency infrared carbon-sulfur analyzer, ensure that the instrument status meets the detection requirements, calibrate the analysis curve, weigh 0.4-0.5g of pure iron particles and spread them on the bottom of the special crucible for carbon-sulfur analysis, then weigh 0.05-0.1g of blast furnace dust ash analysis sample and place it on the pure iron particles, and cover the analysis sample with 1.5-2.0g of tungsten-tin flux particles, put the crucible with the analysis sample on the instrument crucible drag, start the detection program, heat and decompose the analysis sample in the oxygen flow of the high-frequency induction furnace, and the sulfur enters the infrared cell for detection in the form of sulfur dioxide to obtain the air-dried total sulfur content of the analysis sample.

[0024] Furthermore, the specific method for determining the air-dried hydrogen content of the sample in step 5 is as follows: Using CHN element analyzer as the detection instrument, due to the lack of dust ash standard samples containing hydrogen certification value, the method uses the certified coal standard samples with hydrogen content close to that of blast furnace dust ash to establish the hydrogen analysis curve; Turn on the CHN element analyzer and start the heating program. After the instrument is heated up, preheat it for 1 to 2 hours. Perform a system leak check to ensure that the instrument is stable. Before measuring the sample, perform 3 to 5 sets of blank analysis until the instrument reaches a balanced state. Then add 2 to 3 sets of "waste samples" for preheating test. After that, measure the certified coal standard sample to calibrate the instrument for drift. Use a tin paper cup to weigh about 80 mg of blast furnace dust analysis sample, fully burn it in a high-purity oxygen flow, and the hydrogen reaction generates water that enters the infrared cell for detection to obtain the air-dried hydrogen content of the analysis sample.

[0025] It should be further explained that the specific method for determining the calorific value of the sample in step 6 is as follows: Start the calorimeter, set the test system's measurement mode to calorific value, and perform 3 to 5 sets of preheating tests before testing and analyzing the sample to ensure that the instrument is in a stable state. Grind the dried benzoic acid calorific value standard sample into powder with a particle size of ≤0.2mm as an additive, place the pickled asbestos in a muffle furnace at a furnace temperature of 750-850℃ and burn it for 0.5-1h, accurately weigh 0.05-0.3g of benzoic acid powder and 0.7-1.0g of blast furnace dust analysis sample and mix them evenly, input the mass of benzoic acid powder and analysis sample respectively in the test interface, weigh 0.1-0.2g of pickled asbestos after high temperature burning and lay it flat on the bottom of the nickel-chromium combustion dish, then place the mixed sample on the pickled asbestos, gently tap the nickel-chromium combustion dish to make the mixed sample in a vibrated state, then place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, and connect the two ends to the electrode column of the oxygen bomb; Add 5-10mL of distilled water to the oxygen bomb, install the crucible stand, and carefully tighten the oxygen bomb cover. The amount of distilled water added should be consistent with that during the heat capacity calibration. Slowly fill the oxygen bomb with industrial oxygen with a purity of ≥99.5% until the pressure reaches 2.8-3.0MPa. Continue to fill the oxygen for 15-20S after reaching the pressure. Do not use electrolytic oxygen. Put the oxygen bomb into the inner cylinder of the calorimeter and measure the mixed sample. After the measurement, the analysis system will automatically subtract the theoretical calorific value of benzoic acid from the calorific value of the mixed sample to obtain the calorific value of the blast furnace dust sample; And the calorific value of blast furnace dust removal ash cartridge can be calculated by the calculation formula of the calorific value of blast furnace dust removal ash cartridge.

[0026] Furthermore, the calculation formula for the calorific value of the blast furnace dust ash bomb is: Where: Q 1 is the calorific value of the blast furnace dust, in MJ / kg; Q 2 is the calorific value of benzoic acid, in MJ / kg; Q 3 is the measured barrel calorific value of the mixed sample, in MJ / kg; m 1 is the mass of blast furnace dust, in g; m 2 is the mass of benzoic acid powder, in g.

[0027] Furthermore, in step 1 and step 6, the two ends are connected to the oxygen bomb electrode column, and the bent ignition wire maintains good contact with the sample.

[0028] Specific implementation method: 1. Calibrate the heat capacity of the calorimeter Control the test environment temperature to 25±0.1℃ and the humidity to 40%, turn on the calorimeter for preheating, ensure that the instrument status meets the test requirements, change the measurement mode of the test system to benzoic acid standard heat capacity, and enter the calorific value of the fusible ignition wire used, 50J, and the certified value of the benzoic acid calorific value standard sample, 26.465MJ / kg, into the corresponding positions.

[0029] Place the benzoic acid calorific value standard sample in a constant temperature forced air drying oven at 65°C and dry for 4 hours. Weigh about 1.0g of the dried benzoic acid calorific value standard sample and place it in a nickel-chromium combustion dish, and place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb. Take a section of fusible ignition wire, connect both ends to the oxygen bomb electrode column, and bend the ignition wire to maintain good contact with the sample.

[0030] Add 10mL of distilled water to the oxygen bomb, install the crucible stand, and carefully tighten the oxygen bomb cover. Slowly fill the oxygen bomb with industrial oxygen with a purity of ≥99.5% until the pressure reaches 3.0MPa. Continue to oxygenate for 15S when the pressure is reached. Note: The amount of distilled water added needs to be kept constant, otherwise it will cause system errors. Electrolytic oxygen cannot be used. Place the oxygen bomb in the inner cylinder of the calorimeter, measure the calorific value of the benzoic acid standard sample, and obtain the heat capacity data of the calorimeter.

[0031] Repeat the above steps to continuously measure 6 groups of heat capacity data, select 5 groups of heat capacity data with relative standard deviation ≤ 0.20% to calculate the average value, obtain the average heat capacity data of the calorimeter, and complete the calibration.

[0032] 2. Determine the received basic moisture content of the sample Accurately weigh 500±0.1g of blast furnace dust sample and spread it flat in a shallow dish of known mass. Place the shallow dish containing the sample in a constant temperature blast drying oven preheated to 105°C and dry for 2.0h. Take out the shallow dish, cool it at room temperature for 5min, weigh it, record the total mass of the shallow dish and sample after drying, and calculate the received basis moisture content of the sample. Grind the dried sample into an analytical sample with a particle size of ≤0.2mm for the determination of air-dried basis moisture, air-dried basis total sulfur and air-dried basis hydrogen content in subsequent samples.

[0033] 3. Determine the air-dried moisture content of the sample Weigh about 1.0g of the dried analytical sample and place it flat in a flat weighing bottle after drying. Open the bottle cap and place it in a constant temperature blast drying oven preheated to 105°C for 2.0h. Cover the bottle cap, take out the weighing bottle, cool it at room temperature for 5min, weigh it, record the total mass of the flat weighing bottle and the analytical sample after drying, and calculate the air-dried basis moisture content of the analytical sample.

[0034] 4. Determine the total sulfur content of the sample on an air-dried basis A high-frequency infrared carbon-sulfur analyzer was used as the detection instrument, and a certified standard sample of dust ash with a matrix composition and content close to those of blast furnace dust ash was selected to establish a total sulfur analysis curve.

[0035] Start the high-frequency infrared carbon-sulfur analyzer, ensure that the instrument status meets the detection requirements, and calibrate the analysis curve. Weigh 0.4g of pure iron particles and spread them in a special crucible for carbon-sulfur analysis, then weigh 0.1g of blast furnace dust ash analysis sample and place it on the pure iron particles, and cover the analysis sample with 1.5g of tungsten-tin flux particles. The weight of the sample and flux is determined according to the chemical composition of the actual sample. Place the crucible containing the analysis sample on the instrument crucible drag, start the detection program, and heat and decompose the analysis sample in the oxygen flow of the high-frequency induction furnace. The sulfur enters the infrared cell for detection in the form of sulfur dioxide to obtain the air-dried total sulfur content of the analysis sample.

[0036] 5. Determine the air-dried hydrogen content of the sample A CHN element analyzer was used as the detection instrument. Due to the lack of a dust standard sample containing a certified value of hydrogen, a certified coal standard sample with a hydrogen content close to that of blast furnace dust was used to establish a hydrogen analysis curve.

[0037] Turn on the CHN element analyzer, start the heating program, and preheat for 1 hour after the instrument is heated up. Perform a system leak check to ensure that the instrument is stable. Before measuring the sample, perform 5 sets of blank analysis, analyze the blank until the instrument reaches a balanced state, then add 3 sets of "waste samples" for preheating test, and then measure the certified coal standard sample to correct the instrument for drift.

[0038] Use a tin paper cup to weigh about 80 mg of blast furnace dust analysis sample, fully burn it in a high-purity oxygen flow, and the hydrogen reaction generates water that enters the infrared cell for detection to obtain the air-dried hydrogen content of the analysis sample.

[0039] 6. Determine the calorific value of the sample Start the calorimeter, set the measurement mode of the test system to calorific value, and perform three sets of preheating tests before testing and analyzing the samples to ensure that the instrument is in a stable state.

[0040] Grind the dried benzoic acid calorific value standard sample into a powder with a particle size of ≤0.2mm as an additive, and burn the pickled asbestos in a muffle furnace at a furnace temperature of 800℃ for 0.5h. Accurately weigh 0.1g of benzoic acid powder and 0.9g of blast furnace dust ash analysis sample and mix them evenly. Enter the mass of benzoic acid powder and analysis sample in the test interface respectively, and then weigh 0.2g of pickled asbestos after high-temperature burning and lay it flat on the bottom of the nickel-chromium combustion dish, and then place the mixed sample on the pickled asbestos, and gently tap the nickel-chromium combustion dish to make the mixed sample in a vibrated state. Place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, connect the two ends to the electrode column of the oxygen bomb, and bend the ignition wire to maintain good contact with the mixed sample.

[0041] Note: The mass percentage of benzoic acid powder in the mixed sample is not fixed. During the measurement process, the mass percentage of benzoic acid powder in the mixed sample needs to be adjusted according to the actual carbon content in the sample to ensure that the sample can be fully burned. For example, in some embodiments of the present invention, a mixture of 0.2g benzoic acid powder and 0.8g blast furnace dust ash sample is used.

[0042] Add 10mL of distilled water to the oxygen bomb, install the crucible stand, and carefully tighten the oxygen bomb cover. Slowly fill the oxygen bomb with industrial oxygen with a purity of ≥99.5% until the pressure reaches 3.0MPa. The continuous oxygen filling time after reaching the pressure is 15S. Place the oxygen bomb in the inner cylinder of the calorimeter and measure the mixed sample. After the measurement is completed, the analysis system will automatically subtract the theoretical calorific value of the benzoic acid powder from the calorific value of the mixed sample to obtain the calorific value of the blast furnace dust ash sample.

[0043] Where: Q 1 is the calorific value of the blast furnace dust, in MJ / kg; Q 2 is the calorific value of the cartridge of benzoic acid powder, in MJ / kg; Q 3 is the measured barrel calorific value of the mixed sample, in MJ / kg; 7. Calculate high and low heating values When the bomb calorific value determination of the blast furnace dust is completed, the data of the received basis moisture, air-dried basis moisture, air-dried basis total sulfur and air-dried basis hydrogen detected in the above steps are filled into the corresponding positions in the calorific value calculation program in turn to calculate the high and low calorific values ​​of the blast furnace dust.

[0044] Embodiment 1 The high and low calorific values ​​of a portion of blast furnace dust with a carbon content of 21% (from the blast furnace production area of ​​the ironmaking plant, numbered GQ0621) are measured using the technical solution provided in the specific implementation method. The specific detection steps are as follows: 1. Testing equipment and instruments Constant temperature blast drying oven, sample crusher, electronic analytical balance, high frequency infrared carbon and sulfur analyzer, CHN element analyzer, rapid calorimeter.

[0045] 2. Reagents and Materials Tin paper cup, benzoic acid calorific value standard sample (calorific value: 26.465MJ / kg), fusible ignition wire (calorific value 50J), pickled asbestos, industrial oxygen (purity ≥99.50%), high-purity helium (purity ≥99.999%), high-purity oxygen (purity ≥99.999%), nitrogen (purity ≥99.95%).

[0046] 3. Calibrate the heat capacity of the calorimeter Keep the working environment temperature of the calorimeter at 25±0.1℃ and the humidity at 40%. Turn on the calorimeter for preheating, ensure that the instrument status meets the detection requirements, change the measurement mode of the test system to the benzoic acid standard heat capacity, and enter the calorific value of the fusible ignition wire used, 50J, and the calorific value of benzoic acid, 26.465MJ / kg±, into the corresponding positions.

[0047] Place the benzoic acid calorific value standard sample in a constant temperature forced air drying oven at 65°C and dry for 4 hours. Weigh about 1.0g of the dried benzoic acid calorific value standard sample and place it in a nickel-chromium combustion dish, and place the nickel-chromium combustion dish on the oxygen bomb crucible stand. Take a section of fusible ignition wire, connect both ends to the oxygen bomb electrode column, and bend the ignition wire to maintain good contact with the sample.

[0048] Add 10 mL of distilled water to the oxygen bomb, install the crucible stand, carefully tighten the oxygen bomb cover, and then slowly fill the oxygen bomb with industrial oxygen with a purity of ≥99.5% until the internal pressure of the oxygen bomb reaches 3.0 MPa. After reaching the pressure, continue to fill with oxygen for 15 seconds.

[0049] The oxygen bomb containing the benzoic acid sample is placed into the inner cylinder of the calorimeter, and the calorific value of the benzoic acid standard sample is measured to obtain the instrument heat capacity data.

[0050] Repeat the above steps to continuously measure 6 groups of heat capacity data, select 5 groups of heat capacity data with close values ​​and relative standard deviation ≤ 0.2% for average calculation, obtain the average heat capacity data of the instrument, and complete the calibration. The calibration data are shown in Table 1.

[0051] Table 1 Heat capacity calibration data 2. Determine the received basic moisture content of the sample Accurately weigh 500g (accurate to 0.1g) of the blast furnace dust sample to be tested and place it flat in a clean shallow dish of known mass, and place the shallow dish containing the sample in a constant temperature blast drying oven preheated to 105°C for 2.0h. Then take out the shallow dish, cool it at room temperature for 5min, weigh it, record the total mass of the shallow dish and the sample after drying, and calculate the as-received moisture content of the sample. The as-received moisture data is shown in Table 2.

[0052] Table 2 Received base moisture data The dried blast furnace dust ash sample is then ground into an analytical sample with a particle size of ≤0.2 mm for the determination of air-dried basis moisture, air-dried basis total sulfur and air-dried basis hydrogen content in subsequent samples.

[0053] 3. Determine the air-dried moisture content of the sample Weigh about 1.0g of the analysis sample and spread it flat in a flat weighing bottle after drying. Open the bottle cap and put it in a constant temperature blast drying oven preheated to 105°C. After drying for 2.0h, cover the bottle cap, take out the weighing bottle, cool it at room temperature for 5min, weigh it, record the total mass of the flat weighing bottle and the analysis sample after drying, and calculate the air-dried basis moisture content of the analysis sample. The air-dried basis moisture data is shown in Table 3.

[0054] Table 3 Air dried basis moisture data 4. Determine the total sulfur content of the sample on an air-dried basis Start the high-frequency infrared carbon-sulfur analyzer, ensure that the instrument status meets the detection requirements, and select a certified standard sample of dust ash with a matrix composition and content close to that of blast furnace dust ash to establish a total sulfur analysis curve. Weigh 0.4g of pure iron particles and spread them on the bottom of a special crucible for carbon-sulfur analysis, then weigh 0.1g of blast furnace dust ash analysis sample and place it on the pure iron particles, and cover the analysis sample with 1.5g of tungsten-tin flux particles. Place the crucible containing the analysis sample on the instrument crucible drag, start the detection program, and heat and decompose the analysis sample in the oxygen flow of the high-frequency induction furnace. Sulfur enters the infrared cell for detection in the form of sulfur dioxide, and the air-dried total sulfur content of the analysis sample is 0.23%.

[0055] 5. Determine the air-dried hydrogen content of the sample Turn on the CHN element analyzer, start the heating program, preheat for 1 hour after the instrument is heated up, perform a system leak check to ensure that the instrument is stable, and use a certified coal standard sample with a hydrogen content close to that of blast furnace dust to establish a hydrogen analysis curve. Before measuring the sample, first analyze 5 groups of blank samples until the hydrogen blank value is lower than 0.1%, then add 3 groups of "waste samples" for preheating test, and then measure the certified coal standard sample to drift correct the hydrogen analysis curve.

[0056] A blast furnace dust ash analysis sample of about 80 mg was weighed in a tin paper cup and fully burned in a high-purity oxygen flow. The hydrogen reacted to generate water which entered the infrared cell for detection. The air-dried hydrogen content of the analysis sample was 1.26%.

[0057] 6. Determine the calorific value of the sample Grind the dried benzoic acid calorific value standard sample into a powder with a particle size of ≤0.2% as an additive, and burn the acid-washed asbestos in a muffle furnace at a temperature of 800°C for 0.5h. Start the calorimeter, change the measurement mode of the test system to the benzoic acid standard heat capacity, and perform 3 sets of preheating tests before testing and analyzing the sample until the instrument status meets the test requirements.

[0058] Weigh 0.1g of benzoic acid powder and 0.9g of blast furnace dust analysis sample and mix them evenly. Enter the mass of benzoic acid powder and analysis sample in the test interface respectively. Then weigh 0.2g of acid-washed asbestos burned at high temperature and lay it flat on the bottom of the nickel-chromium combustion dish. Then place the mixed sample on the acid-washed asbestos and gently tap the nickel-chromium combustion dish to make the mixed sample in a vibrated state. Place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, connect the two ends to the oxygen bomb electrode column, and bend the ignition wire to maintain good contact with the mixed sample.

[0059] Add 10mL of distilled water to the oxygen bomb, install the crucible stand, and carefully tighten the oxygen bomb cover. Slowly fill the oxygen bomb with industrial oxygen with a purity of ≥99.5% until the pressure reaches 3.0MPa. Continue to fill the oxygen for 15S after reaching the pressure. Place the oxygen bomb in the inner cylinder of the calorimeter and measure the mixed sample. After the measurement, the analysis system will automatically subtract the theoretical calorific value of benzoic acid from the calorific value of the mixed sample to obtain the calorific value of the blast furnace dust ash sample. The calorific value data of the blast furnace dust ash are shown in Table 4.

[0060] Table 4 Calorific value of blast furnace dust removal ash bomb 6. Calculate the high and low calorific values ​​of blast furnace dust After the bomb calorific value determination of the blast furnace dust is completed, the data of the received basis moisture, air-dried basis moisture, air-dried basis total sulfur and air-dried basis hydrogen detected in the above steps are filled into the corresponding positions in the calorific value calculation program in turn, and the high and low calorific values ​​of the blast furnace dust are calculated. The calorific value data are shown in Table 5.

[0061] Table 5 High and low calorific values ​​of blast furnace dust GQ0621 There is a large difference in the residual coal powder content in each batch of blast furnace dust collected. In order to ensure the combustibility of the sample, when the residual coal powder in the sample is less, the mass proportion of auxiliary fuel benzoic acid in the mixed sample can be appropriately increased.

[0062] Embodiment 2 Precision test of the invention method In order to verify the accuracy of the method of the present invention in determining the high and low calorific values ​​of blast furnace dust ash, 5 blast furnace dust ash samples with different amounts of residual coal powder were randomly selected for testing. Each sample was continuously measured 6 times using the method provided in the specific implementation method. The test results of the high and low calorific values ​​and the accuracy calculation data (RSD, %) are shown in Table 6.

[0063] Table 6 Accuracy results of the inventive method The test shows that the relative standard deviation (RSD, %) of the measured lower calorific value on received basis, higher calorific value on air dried basis and higher calorific value on dry basis of blast furnace dust ash is 0.22%~0.55%, which has good accuracy.

[0064] Embodiment 3 Invention method correctness test Since there is a lack of certified calorific value standard samples of blast furnace dust ash with set values ​​in the market at this stage, in order to verify the accuracy of the method of the present invention in determining the high and low calorific values ​​of blast furnace dust ash, the test was carried out by mixing the blast furnace dust ash (No. GQ0621, the actual measured value of the high calorific value on a dry basis is 5.153MJ / kg) and the certified coal standard sample GBW111101u (the certified value of the dry basis calorific value is 31.490MJ / kg, and the uncertainty is 0.160MJ / kg) in different proportions to obtain 4 mixed samples, and each mixed sample was measured according to the technical scheme provided in the specific implementation method. Since the certified coal standard sample only gives the calorific value of the dry basis calorific value, the test only compares the measured dry basis high calorific value of the mixed sample with the theoretical dry basis high calorific value, and the comparison results are shown in Table 7.

[0065] Table 7 Correctness verification results of the invention method The experiment shows that by using the technical solution provided in the specific implementation method to measure four mixed samples, the actual data of the higher calorific value on a dry basis obtained are basically consistent with the theoretical data, and the difference is within 0.04MJ / kg, which has a high degree of accuracy.

[0066] Embodiment 4 Applicability test of the invention method The lower the residual coal powder content in the blast furnace dust, the more difficult it is to detect its calorific value. In order to verify whether the method of the present invention can be used to measure blast furnace dust with low carbon content, a blast furnace dust sample with a carbon content of 4.8% was experimentally extracted and measured according to the technical solution provided in the specific implementation method.

[0067] According to the technical solution provided in the specific implementation method, the moisture, total sulfur and hydrogen content of the sample can be accurately measured. However, when measuring the calorific value of the sample, due to the low carbon content in the sample, it is difficult to fully burn the sample by mixing 0.1g of benzoic acid powder with 0.9g of sample. Therefore, in this embodiment, the mass proportion of benzoic acid powder is appropriately increased, that is, 0.2g of benzoic acid powder is mixed with 0.8g of sample, so that the sample can be fully burned. The test data is shown in Table 8.

[0068] Table 8 Determination data of blast furnace dust samples with low carbon content Experiments show that the method of the present invention can be used to determine the high and low calorific values ​​of blast furnace dust ash with low carbon content. However, during the determination process, the mass percentage of benzoic acid powder in the mixed test needs to be adjusted according to the actual carbon content in the sample to ensure that the sample can be fully burned.

[0069] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the residual coal powder content in each batch of blast furnace dust collected before is quite different, in order to ensure the combustibility of the sample, when there is less residual coal powder in the sample, the mass proportion of auxiliary fuel benzoic acid in the mixed sample can be appropriately increased. The examples illustrate the present invention in detail. For those skilled in the art, they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the high and low calorific values ​​of blast furnace dust, characterized in that: The specific steps include: Step 1: Calibrate the heat capacity of the calorimeter Control the test environment temperature and humidity, turn on the calorimeter to preheat the instrument, change the measurement mode of the test system to benzoic acid standard heat capacity, and enter the calorific value of the fusible ignition wire used and the certified value of the calorific value standard sample of benzoic acid into the corresponding positions; Place the benzoic acid calorific value standard sample in a constant temperature forced air drying oven for drying, weigh the dried benzoic acid calorific value standard sample and place it in a nickel-chromium combustion dish, then place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, and connect the two ends to the electrode column of the oxygen bomb; Add distilled water to the oxygen bomb, install the crucible stand, keep the amount of distilled water added each time constant, slowly fill the oxygen bomb with industrial oxygen until the pressure reaches the set pressure, continue to oxygenate for a while after reaching the pressure, put the oxygen bomb into the inner cylinder of the calorimeter, measure the calorific value of benzoic acid standard sample, and obtain the instrument heat capacity data; Repeat the above steps to continuously measure multiple groups of heat capacity data, and select some groups of heat capacity data to calculate the average value, obtain the average heat capacity data of the instrument, and complete the calibration; Step 2: Determine the received basic moisture content of the sample Weigh the blast furnace dust sample and spread it flat in a shallow dish of known mass. Put the shallow dish with the sample into a constant temperature blast drying oven preheated to a certain temperature and dry it. Take out the shallow dish, cool it at room temperature for a period of time and weigh it. Record the total mass of the shallow dish and the sample after drying, and calculate the as-received moisture content of the sample. Step 3: Determine the air-dried moisture content of the sample Weigh the analysis sample and place it flat in a flat weighing bottle after drying, and put it into a constant temperature blast drying oven preheated to a certain temperature. After drying for a period of time, take out the weighing bottle, cool it for a period of time at room temperature, and weigh it. Record the total mass of the flat weighing bottle and the analysis sample after drying, and calculate the air-dried basis moisture content of the analysis sample. Step 4: Determine the total sulfur content of the sample on an air-dried basis A high-frequency infrared carbon-sulfur analyzer was used as the detection instrument, and a certified standard sample of dust ash with a matrix composition and content close to that of blast furnace dust ash was selected to establish a total sulfur analysis curve. Start the high-frequency infrared carbon-sulfur analyzer, ensure that the instrument status meets the detection requirements, calibrate the analysis curve, weigh pure iron particles and spread them on the bottom of the special crucible for carbon-sulfur analysis, then weigh the blast furnace dust ash analysis sample and place it on the pure iron particles, and cover the analysis sample with tungsten-tin flux particles, put the crucible containing the analysis sample on the instrument crucible drag, start the detection program, and heat the analysis sample in the oxygen flow of the high-frequency induction furnace to decompose. The sulfur enters the infrared cell for detection in the form of sulfur dioxide to obtain the air-dried total sulfur content of the analysis sample; Step 5: Determine the air-dried hydrogen content of the sample Using CHN element analyzer as the detection instrument, due to the lack of dust ash standard samples containing hydrogen certification value, the method uses the certified coal standard samples with hydrogen content close to that of blast furnace dust ash to establish the hydrogen analysis curve; Turn on the CHN element analyzer, start the heating program, preheat the instrument after it has finished heating, perform a system leak check to ensure that the instrument is in a stable state, and before measuring the sample, perform multiple sets of blank analysis until the instrument reaches a balanced state, then add multiple sets of "waste samples" for preheating tests, and then measure the certified coal standard sample to perform drift correction on the instrument; Use a tin paper cup to weigh the blast furnace dust analysis sample, fully burn it in a high-purity oxygen flow, and the hydrogen reaction generates water that enters the infrared cell for detection to obtain the air-dried hydrogen content of the analysis sample; Step 6: Determine the calorific value of the sample Start the calorimeter, set the measurement mode of the test system to calorific value, and perform multiple sets of preheating tests before testing and analyzing the samples to ensure the stability of the instrument; Grind the dried benzoic acid calorific value standard sample into powder as an additive, burn the pickled asbestos in a muffle furnace, weigh the benzoic acid powder and the blast furnace dust ash analysis sample and mix them evenly, input the mass of the benzoic acid powder and the analysis sample in the test interface respectively, weigh the pickled asbestos after high temperature burning and lay it flat on the bottom of the nickel-chromium combustion dish, then place the mixed sample on the pickled asbestos, gently tap the nickel-chromium combustion dish to make the mixed sample in a vibrated state, then place the nickel-chromium combustion dish on the oxygen bomb crucible rack, take a section of fusible ignition wire, and connect both ends to the oxygen bomb electrode column; Add distilled water to the oxygen bomb, install the crucible stand, keep the amount of distilled water added consistent with that during heat capacity calibration, slowly fill the oxygen bomb with industrial oxygen until the pressure reaches the set pressure, continue to fill with oxygen for a period of time after reaching the pressure, put the oxygen bomb into the inner cylinder of the calorimeter, and measure the mixed sample. After the measurement, the analysis system will automatically subtract the theoretical calorific value of benzoic acid from the calorific value of the mixed sample to obtain the calorific value of the blast furnace dust sample; And the calorific value of blast furnace dust removal ash cartridge can be calculated by the calculation formula of blast furnace dust removal ash cartridge calorific value; Step 7: Calculate high and low calorific values When the calorific value of the blast furnace dust ash cartridge is determined, the data of the received basis moisture, air dried basis moisture, air dried basis total sulfur and air dried basis hydrogen detected in the above steps are filled into the corresponding positions in the calorific value calculation program in turn to calculate the high and low calorific values ​​of the blast furnace dust ash.

2. The method for determining the high and low calorific values ​​of blast furnace dust according to claim 1, characterized in that: The specific method for calibrating the heat capacity of the calorimeter in step 1 is as follows: Control the test environment temperature to 24-26℃ and the humidity to 40%-85%. Turn on the calorimeter to preheat the instrument to ensure that the instrument status meets the test requirements. Change the measurement mode of the test system to benzoic acid standard heat capacity. Enter the calorific value of the fusible ignition wire used and the certified value of the benzoic acid calorific value standard sample into the corresponding positions. The calorific value of the ignition wire is 25-50J, and the certified value of the benzoic acid calorific value standard sample is 26.465-26.470MJ / kg. Place the benzoic acid calorific value standard sample in a constant temperature forced air drying oven at 60-70℃ for 3-4h, weigh 1.0-1.5g of the dried benzoic acid calorific value standard sample and place it in a nickel-chromium combustion dish, then place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, and connect the two ends to the electrode column of the oxygen bomb; Add 5-10 mL of distilled water to the oxygen bomb, install the crucible stand, and carefully tighten the oxygen bomb cover. The amount of distilled water added each time must be kept constant. Slowly fill the oxygen bomb with industrial oxygen with a purity of ≥99.5% until the pressure reaches 2.8-3.0 MPa. After reaching the pressure, continue to oxygenate for 15-20S. Do not use electrolytic oxygen. Place the oxygen bomb in the inner cylinder of the calorimeter, measure the calorific value of the benzoic acid standard sample, and obtain the instrument's heat capacity data.

3. The method for determining the high and low calorific values ​​of blast furnace dust according to claim 1, characterized in that: The specific method for determining the received basic moisture content of the sample in step 2 is as follows: Weigh 490-510g of blast furnace dust sample and spread it evenly in a shallow dish of known mass. Place the shallow dish with the sample in a constant temperature forced air drying oven preheated to 105-110°C and dry for 1.5-2.0h. Take out the shallow dish and cool it at room temperature for 5-10min. Weigh it and record the total mass of the shallow dish and sample after drying. Calculate the as-received moisture content of the sample.

4. The method for determining the high and low calorific values ​​of blast furnace dust according to claim 1, characterized in that: The specific method for determining the air-dried basis moisture of the sample in step 3 is as follows: Weigh about 1.0 g of the analytical sample and spread it flat in a flat weighing bottle after drying. Open the bottle cap and put it into a constant temperature forced air drying oven preheated to 105-110°C for drying for 1.5-2.0 hours. Cover the bottle cap, take out the weighing bottle, cool it at room temperature for 5-10 minutes, weigh it, record the total mass of the flat weighing bottle and the analytical sample after drying, and calculate the air-dried basis moisture content of the analytical sample.

5. The method for determining the high and low calorific values ​​of blast furnace dust according to claim 1, characterized in that: The specific method for determining the air-dried total sulfur content of the sample in step 4 is as follows: A high-frequency infrared carbon-sulfur analyzer was used as the detection instrument, and a certified standard sample of dust ash with a matrix composition and content close to that of blast furnace dust ash was selected to establish a total sulfur analysis curve. Start the high-frequency infrared carbon-sulfur analyzer, ensure that the instrument status meets the detection requirements, calibrate the analysis curve, weigh 0.4-0.5g of pure iron particles and spread them on the bottom of the special crucible for carbon-sulfur analysis, then weigh 0.05-0.1g of blast furnace dust ash analysis sample and place it on the pure iron particles, and cover the analysis sample with 1.5-2.0g of tungsten-tin flux particles, put the crucible with the analysis sample on the instrument crucible drag, start the detection program, heat and decompose the analysis sample in the oxygen flow of the high-frequency induction furnace, and the sulfur enters the infrared cell for detection in the form of sulfur dioxide to obtain the air-dried total sulfur content of the analysis sample.

6. The method for determining the high and low calorific values ​​of blast furnace dust according to claim 1, characterized in that: The specific method for determining the air-dried hydrogen content of the sample in step 5 is as follows: Using CHN element analyzer as the detection instrument, due to the lack of dust ash standard samples containing hydrogen certification value, the method uses the certified coal standard samples with hydrogen content close to that of blast furnace dust ash to establish the hydrogen analysis curve; Turn on the CHN element analyzer and start the heating program. After the instrument is heated up, preheat it for 1 to 2 hours. Perform a system leak check to ensure that the instrument is stable. Before measuring the sample, perform 3 to 5 sets of blank analysis until the instrument reaches a balanced state. Then add 2 to 3 sets of "waste samples" for preheating test. After that, measure the certified coal standard sample to calibrate the instrument for drift. Use a tin paper cup to weigh about 80 mg of blast furnace dust analysis sample, fully burn it in a high-purity oxygen flow, and the hydrogen reaction generates water that enters the infrared cell for detection to obtain the air-dried hydrogen content of the analysis sample.

7. The method for determining the high and low calorific values ​​of blast furnace dust according to claim 1, characterized in that: The specific method for determining the calorific value of the cartridge of the sample in step 6 is as follows: Start the calorimeter, set the test system's measurement mode to calorific value, and perform 3 to 5 sets of preheating tests before testing and analyzing the sample to ensure that the instrument is in a stable state. Grind the dried benzoic acid calorific value standard sample into powder with a particle size of ≤0.2mm as an additive, burn the pickled asbestos in a muffle furnace at a furnace temperature of 750-850℃ for 0.5-1h, accurately weigh 0.05-0.3g of benzoic acid powder and 0.7-1.0g of blast furnace dust analysis sample and mix them evenly, enter the mass of benzoic acid powder and analysis sample in the test interface respectively, weigh 0.1-0.2g of pickled asbestos burned at high temperature and lay it flat on the bottom of the nickel-chromium combustion dish, then place the mixed sample on the pickled asbestos, gently tap the nickel-chromium combustion dish to make the mixed sample in a vibrated state, then place the nickel-chromium combustion dish on the crucible stand of the oxygen bomb, take a section of fusible ignition wire, and connect the two ends to the electrode column of the oxygen bomb, Add 5-10mL of distilled water to the oxygen bomb, install the crucible stand, and carefully tighten the oxygen bomb cover. The amount of distilled water added should be consistent with that during the heat capacity calibration. Slowly fill the oxygen bomb with industrial oxygen with a purity of ≥99.5% until the pressure reaches 2.8-3.0MPa. Continue to fill the oxygen for 15-20S after reaching the pressure. Do not use electrolytic oxygen. Put the oxygen bomb into the inner cylinder of the calorimeter and measure the mixed sample. After the measurement, the analysis system will automatically subtract the theoretical calorific value of benzoic acid from the calorific value of the mixed sample to obtain the calorific value of the blast furnace dust sample; And the calorific value of blast furnace dust removal ash cartridge can be calculated by the calculation formula of the calorific value of blast furnace dust removal ash cartridge.

8. The method for determining the high and low calorific values ​​of blast furnace dust according to claim 7, characterized in that: The calculation formula of the calorific value of the blast furnace dust removal ash cartridge is: Where: Q1 is the calorific value of the blast furnace dust, in MJ / kg; Q2 is the cartridge calorific value of benzoic acid, in MJ / kg; Q3 is the measured barrel calorific value of the mixed sample, in MJ / kg; m1 is the mass of blast furnace dust, in g; m2 is the mass of benzoic acid powder, in g.

9. The method for determining the high and low calorific values ​​of blast furnace dust according to claim 1, characterized in that: In the step 1 and the step 6, the two ends are connected to the oxygen bomb electrode column, and the bent ignition wire maintains good contact with the sample.

10. The method for determining the high and low calorific values ​​of blast furnace dust according to claim 2, characterized in that: The specific method for calibrating the heat capacity of the calorimeter in step 1 also includes the following method: Repeat the above steps to continuously measure 6 to 8 groups of heat capacity data, and select 5 groups of heat capacity data with relative standard deviation ≤ 0.2% to calculate the average value, obtain the average heat capacity data of the instrument, and complete the calibration.

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