A method of chemical analysis for detecting silicon carbide-containing refractory materials

Abstract

The present application relates to a kind of detection containing silicon carbide refractory chemical analysis method, including the establishment of XRF fluorescence aluminum silicon containing silicon carbide refractory working curve;According to GB / T21114-2019 X-ray fluorescence spectrochemical analysis glass casting piece method, a certain amount of oxidizing agent is added in containing silicon carbide refractory sample at the temperature set, time, makes it completely oxidized and obtains uniform glass sheet, then the required chemical composition is detected on X-ray fluorescence spectrometer.The method of the present application can reduce the systematic error and process error in the chemical analysis and detection of containing silicon carbide refractory, improve the detection accuracy, shorten the inspection cycle, improve work efficiency.

Description

Technical Field

[0001] This invention relates to a method for detecting silicon carbide-containing refractory materials used in iron and steel smelting, specifically a chemical analysis method for detecting silicon carbide-containing refractory materials. Background Technology

[0002] The general testing methods for silicon carbide-containing refractory materials are based on the national standard GB / T16555-2017 Chemical Analysis Methods for Carbon-Containing, Silicon Carbide and Nitride-Containing Refractory Materials.

[0003] The advantage of this detection method is that the equipment is simple, and it can generally be performed by any laboratory capable of performing wet chemistry.

[0004] The disadvantage of this detection method is:

[0005] 1) The detection efficiency is not high, and different sample processing methods are required for the quantitative analysis of each component;

[0006] 2) The testing process involves a large number of devices, utensils, and reagents, and systematic errors will be carried over into the overall experimental error.

[0007] 3) Too many manual operation steps will cause process errors to be carried into the overall experimental error;

[0008] 4) Most of the data is calculated manually, which is time-consuming, inefficient, and results in large fluctuations in test results.

[0009] To reduce systematic and process errors in the chemical analysis and testing of silicon carbide-containing refractory materials, improve testing accuracy, shorten the inspection cycle, and increase work efficiency, we adopted the glass fusing method of GB / T21114-2019 for X-ray fluorescence spectrochemical analysis. A certain amount of oxidant is added to the silicon carbide-containing refractory material sample, and the sample is subjected to complete oxidation within a set temperature and time to obtain a uniform glass slide. The desired chemical composition is then detected using an X-ray fluorescence spectrometer. This method is convenient, scientific, and rational. Summary of the Invention

[0010] This invention provides a chemical analysis method for detecting silicon carbide-containing refractory materials, which can reduce systematic and process errors in the chemical analysis and detection of silicon carbide-containing refractory materials, improve detection accuracy, shorten the inspection cycle, and improve work efficiency.

[0011] To achieve the above objectives, the present invention employs the following technical solution:

[0012] A chemical analysis method for detecting silicon carbide-containing refractory materials, the specific method comprising:

[0013] 1) Establishment of the pre-oxidation working curve: Since potassium nitrate and barium peroxide react violently and splash at 700°C when added to a sample without silicon carbide, this invention selects calcined potassium carbonate and barium carbonate instead of potassium nitrate and barium peroxide to pre-oxidize the standard substance in the process of establishing the pre-oxidation working curve.

[0014] a) Boil potassium carbonate and barium carbonate at 1100℃ to constant weight and place them in a desiccator for later use;

[0015] b) Mix the mixture of anhydrous lithium tetraborate and lithium metaborate with the standard material. Place the mixture with the potassium carbonate and barium carbonate obtained in step a) into a platinum crucible and mix thoroughly. Then place it in an automatic melting machine and melt at 1100°C for 10-20 minutes to obtain a uniform standard material glass slide.

[0016] c) Establish a working curve on the XRF fluorescence spectrometer. Input the corresponding contents of SiO2, Al2O3, Fe2O3, TiO2, CaO, and Fe2O3 in the standard material glass slides obtained in step b) into the working curve. Set the spectrometer current, voltage, detector, crystal, slit, sensitivity, and sampling time parameters. Select the sample with the highest standard values ​​of SiO2, Al2O3, Fe2O3, TiO2, CaO, and Fe2O3 from the series of standard materials and scan them on the XRF fluorescence spectrometer using 2θ and PHD. After determining the 2θ angle and PHD range, register the intensity of the detected elements according to the previously entered standard material order.

[0017] 2) Sample and flux treatment:

[0018] a) High-temperature treatment: In accordance with the provisions of GB / T16555-2017, the silicon carbide refractory test sample was burned at 850±20℃ in an oxidizing atmosphere for 3 hours, and the loss on ignition (LOI) was calculated based on the mass loss.

[0019] b) Flux treatment: Place the mixture of anhydrous lithium tetraborate and lithium metaborate into a platinum crucible and melt it in an automatic melting furnace for 10-20 minutes. When the liquid is taken out of the furnace, shake the crucible to make the flux stick to the walls and bottom of the platinum crucible.

[0020] c) Pre-oxidation treatment: The test sample is thoroughly mixed with potassium nitrate and barium peroxide in a platinum crucible with a platinum base, and then placed in a muffle furnace at 650℃-800℃, preferably 700±25℃, for 30 minutes for pre-oxidation; then placed in an automatic melting machine at 1025℃-1150℃ for 10-20 minutes to obtain a uniform glass slide.

[0021] 3) Detection and calculation of the content of the sample to be tested:

[0022] a) Determination of total carbon content: In accordance with the provisions of GB / T16555-2017 standard, the total carbon content in the sample is quantitatively determined by using a carbon-sulfur analyzer through high-frequency furnace combustion infrared absorption method.

[0023]

[0024] ω(LOI) 850℃ According to GB / T16555-2017, the loss on ignition after holding at 850±20℃ for 3 hours, %;

[0025] m1: The numerical value of the mass of the sample and crucible before ignition, in grams (g);

[0026] m2: The numerical value of the mass of the sample and crucible after ignition, in grams (g);

[0027] m0: The numerical value of the mass of the empty crucible, in grams (g);

[0028] b) Determination of silicon carbide content: According to the standard GB / T16555-2017, the sample is burned off free carbon at 850℃, and then the total carbon content of the residue after burning at 850℃ (i.e. the bound carbon in the sample) is determined to obtain the silicon carbide content in the sample. The total carbon content of the residue after burning at 850℃ can be determined using a high-frequency infrared carbon-sulfur analyzer.

[0029] ω(SiC)=ω(TC*)×3.3384×[1-ω(LOI) 850℃ / 100]

[0030] ω(SiC): Mass fraction of silicon carbide in the sample, %;

[0031] ω(TC * ) 850℃ The total carbon content (%) of the residue after the sample was ignited at 850℃;

[0032] c) Determination of SiO2, Al2O3, Fe2O3, TiO2, CaO, and Fe2O3: Place the glass slide of the sample to be tested on an XRF fluorescence spectrometer, select the pre-oxidation working curve, scan to obtain the detection data, and calculate using the pre-oxidation calculation formula. The pre-oxidation calculation formula is as follows:

[0033]

[0034] ω(SiO2)=ω(SiO2)*×[1-ω(LOI) 850℃ / 100]-ω(SiC)×1.4985

[0035] ω(A x O y ): Content of various oxides in the sample;

[0036] ω(R x O y ): The content of various oxides obtained by scanning the fluorescence pre-oxidation working curve;

[0037] ω(SiO2) * Total silica content in the sample, %:

[0038] ω(SiO2): Silica content in the sample, %.

[0039] In the field of refractory materials, we only focus on the content of SiO2, Al2O3, Fe2O3, TiO2, CaO, Fe2O3, SiC, C, and LOI.

[0040] The amount of potassium oxide and barium oxide obtained after the potassium carbonate and barium carbonate are decomposed at 1100℃ is equal to the amount of potassium oxide and barium oxide obtained after the reaction and decomposition of potassium carbonate and barium carbonate. The mass ratio of anhydrous lithium tetraborate to lithium metaborate is 67:33.

[0041] The mass ratio of the mixture of anhydrous lithium tetraborate and lithium metaborate to the standard substance is 10:1.

[0042] The spectrometer current is set to 5-130mA, the voltage to 10-40kV, the detector to be (FPC, SC), the crystal to be (Ge, LiF, PET, TAP), the slit to be (High Res, Standard, High Sens), and the sampling time to be 10s-80s.

[0043] Equipment: 0.0001 g electronic balance, XRF fluorescence spectrometer, fully automatic fluorescence melting machine, medium-temperature resistance furnace, platinum crucible and mold;

[0044] Chemicals: Potassium nitrate, barium peroxide, potassium carbonate, barium carbonate, a series of standard substances, anhydrous lithium tetraborate and lithium metaborate mixture (analytical grade).

[0045] Compared with the prior art, the beneficial effects of the present invention are:

[0046] This invention first establishes the working curve of XRF fluorescence aluminum-silicon-based silicon carbide-containing refractory materials. Then, according to GB / T21114-2019 X-ray fluorescence spectrochemical analysis glass melting and casting method, a certain amount of oxidant is added to the silicon carbide-containing refractory material sample and oxidized completely at a set temperature and time to obtain a uniform glass sheet. The required chemical composition is then detected on an X-ray fluorescence spectrometer.

[0047] Directly using the X-ray fluorescence spectrochemical analysis glass casting method (GB / T21114-2019) for silicon carbide-containing refractory materials will corrode the platinum crucible and result in uneven glass sheets, especially when pre-oxidation of silicon carbide is involved. This invention enables the detection of silicon carbide-containing refractory materials using the fluorescent glass casting method to obtain uniform glass sheets.

[0048] The method of this invention can reduce systematic and process errors in the chemical analysis and testing of silicon carbide-containing refractory materials, improve testing accuracy, shorten the inspection cycle, and increase work efficiency; it is convenient, scientific, and reasonable to operate. The silicon carbide testing range is (0-30)%. Attached Figure Description

[0049] Figure 1 The image shows the intensity spectrum of the XRF fluorescence spectrometer before oxidation (containing oxidant) in the example (MgO).

[0050] Figure 2 The image shows the intensity spectrum of the pre-oxidation (containing oxidant) working curve of the XRF fluorescence spectrometer (Al2O3) in this example.

[0051] Figure 3 The image shows the intensity spectrum (SiO2) of the pre-oxidized (containing oxidant) working curve of the XRF fluorescence spectrometer in this example.

[0052] Figure 4 The image shows the intensity spectrum (CaO) of the pre-oxidized (containing oxidant) working curve of the XRF fluorescence spectrometer as an example.

[0053] Figure 5 The image shows the intensity spectrum of the pre-oxidation (containing oxidant) working curve (TiO2) of the XRF fluorescence spectrometer in this example.

[0054] Figure 6 The image shows the intensity spectrum of the pre-oxidation (containing oxidant) working curve (Fe2O3) of the XRF fluorescence spectrometer used in this example. Detailed Implementation

[0055] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0056] Example:

[0057] (I) Establishment of the pre-oxidation (containing oxidant) working curve:

[0058] 1) Boil potassium carbonate (analytical grade) and barium carbonate (analytical grade) at 1100℃ to constant weight and place them in a desiccator for later use.

[0059] 2) Weigh the standard substance and the mixture of anhydrous lithium tetraborate and lithium metaborate (analytical grade) at a ratio of 1:10, and weigh 0.7g:7g to 0.1mg using a 0.01g balance; then weigh 0.70g of calcined potassium carbonate (analytical grade) and 1.36g of barium carbonate (analytical grade) to 0.1mg using the same 0.01g balance. Mix each weighed standard substance thoroughly in a platinum crucible, and then melt it in an automatic melting machine at 1100℃ for 15 minutes to obtain a uniform standard substance glass slide;

[0060] 3) Establish a working curve. Input the corresponding contents of SiO2, Al2O3, Fe2O3, TiO2, CaO and MgO in all molten standard substances into the working curve. Select and set the current, voltage, detector, crystal, slit and sampling time for SiO2, Al2O3, Fe2O3, TiO2, CaO and MgO respectively (see Table 1).

[0061] Table 1:

[0062] Element name Current Voltage detector crystal Slit Sampling time <![CDATA[Al2O3]]> 70mA 40kV FPC PET Standard 30s CaO 70mA 40kV FPC LiF Standard 30s <![CDATA[Fe2O3]]> 70mA 40kV SC LiF Standard 30s <![CDATA[TiO2]]> 70mA 40kV SC LiF Standard 30s <![CDATA[SiO2]]> 70mA 40kV FPC PET Standard 40s MgO 130mA 30kV FPC TAP Standard 60s

[0063] Among the series of standard reference materials, samples with the highest standard values ​​of SiO2, Al2O3, Fe2O3, TiO2, CaO, and Fe2O3 were selected and scanned using an XRF fluorescence spectrometer at 2θ and PHD. After determining the 2θ angle and PHD range, the intensity of the detected elements was registered according to the previously entered order of standard reference materials. After confirming that the curve was linear and matrix corrected, it was verified using standard reference materials, and the error conformed to the GB / T21114-2019 standard for X-ray fluorescence spectrochemical analysis of glass fusing methods.

[0064] (II) Pre-oxidation treatment of the test samples:

[0065] 1) Weigh 7g of anhydrous lithium tetraborate and lithium metaborate mixture (analytical grade) to 0.1mg using a balance of 0.001g and melt it in an automatic melting furnace for 15min. To avoid the silicon carbide corroding the platinum crucible during the pre-oxidation process, use platinum-coated crucible tongs to hold the crucible and shake it evenly when the liquid is taken out of the furnace, so that the flux sticks to the wall and bottom of the platinum crucible.

[0066] 2) Weigh 0.7g (accurate to 0.1mg) of the silicon carbide refractory sample to be tested (calcined at 850±20℃ for 3 hours according to GB / T16555-2017) using a 0.01g balance. Then, weigh 1.5g (accurate to 0.1mg) each of potassium nitrate and barium peroxide using the same 0.01g balance. Mix the weighed sample with the nitrate and barium peroxide thoroughly in a platinum crucible with a platinum coating. Pre-oxidize the mixture in a muffle furnace at 700℃ for 30min. Then, melt the mixture in an automatic melting machine at 1100℃ for 15min to obtain a uniform glass slide.

[0067] 3) Place the molten glass slide of the test sample on the XRF fluorescence spectrometer, select the pre-oxidation working curve, scan it, and upload the detection data to the company's quality management system. Then, use the pre-oxidation calculation formula to calculate the results with one click. Table 2 shows a comparison of the wet method and the pre-oxidation fluorescence working curve method for detecting silicon carbide refractory material samples in the example.

[0068] Table 2 Comparison of wet method and pre-oxidation fluorescence working curve method data for silicon carbide refractory material samples in the examples.

[0069]

[0070]

[0071] The XRF fluorescence working curve method for pre-oxidation of silicon carbide refractory materials of this invention has been implemented since 2018. In addition to periodically checking for drift in the pre-oxidation working curve, it is also periodically calibrated using wet methods and outsourced aluminum silicon carbide samples, as shown in Table 1. The parallel calibration error range of the test results conforms to GB / T16555-2017 and GB / T21114-2019 standards. The method combines fluorescence detection with an automated system, offering simple and fast one-click data extraction and calculation. Testing silicon carbide-containing refractory materials using the GB / T16555-2017 standard, assuming six samples treated at 850℃ at a time, requires 16 hours of processing time. Furthermore, the numerous volumetric and quantitative pipetting steps during sample preparation significantly impact subsequent testing, increasing the likelihood of systematic errors. Additionally, the wet method for testing silicon carbide-containing refractory materials has several limitations, including constraints on equipment, personnel, and instruments. The titration endpoint color is also significantly affected by lighting conditions (cloudy days, sunny days, and artificial light). In contrast, the pre-oxidation XRF fluorescence curve method for silicon carbide-containing refractory materials takes less than 4 hours from sample weighing after 850℃ treatment, pre-oxidation, XRF scanning, to one-click result calculation. This method is shorter, less constrained by equipment, instruments, personnel, and weather conditions.

Claims

1. A method of chemical analysis for detecting a silicon carbide-containing refractory material, characterized by, The specific method comprises: 1) establishment of pre-oxidation working curve: a) burn potassium carbonate and barium carbonate to constant weight at 1100 DEG C, and place in a desiccator for standby; b) mix the mixture of anhydrous lithium tetraborate and lithium metaborate with standard substance, mix the mixture with potassium carbonate and barium carbonate obtained in step a) in a platinum yellow crucible, and then place in an automatic sample melting machine and melt at 1100 DEG C for 10-20 minutes to obtain uniform standard substance glass sheet; c) establish working curve on XRF fluorescence spectrometer, enter the corresponding content of SiO2, Al2O3, Fe2O3, TiO2 and CaO in the standard substance glass sheet obtained in step b) into the working curve, set the parameters of spectrometer current, voltage, detector, crystal, slit, sensitivity and sampling time, select the sample sheet with the highest standard value of SiO2, Al2O3, Fe2O3, TiO2 and CaO content in the series of standard substances, and scan on XRF fluorescence spectrometer to select 2 theta and PHD, and after determining the 2 theta angle and PHD range, record the detection element intensity in the order of the standard substance entered before; 2) sample to be tested and flux treatment: a) calcine the silicon carbide-containing refractory material sample to be tested in an oxidizing atmosphere at 850±20 DEG C for 3 hours, and calculate the ignition loss by mass loss; b) place the mixture of anhydrous lithium tetraborate and lithium metaborate in a platinum yellow crucible, melt in an automatic sample melting furnace for 10-20 minutes, and shake the crucible when the liquid is discharged from the furnace to make the flux hang on the wall and bottom in the platinum yellow crucible; c) mix the sample to be tested with potassium nitrate and barium peroxide in the platinum yellow crucible with wall hanging and bottoming, and place in a muffle furnace at 650 DEG C-800 DEG C for pre-oxidation for 30 min; then place in an automatic sample melting machine and melt at 1050 DEG C-1150 DEG C for 10-20 minutes to obtain uniform glass sheet; 3) detection and calculation of content of sample to be tested: a) determination of total carbon content: according to the standard specified in GB / T16555-2017, use high-frequency furnace combustion infrared absorption method, and use carbon and sulfur analyzer to quantitatively measure the total carbon content in the sample; ； ω (LOI) 850℃ : Loss on ignition according to GB / T 16555-2017, % after 850 ± 20 °C for 3 hours m1: the numerical value of the mass of the sample and the crucible before ignition, unit: gram (g); m2: the numerical value of the mass of the sample and the crucible after ignition, unit: gram (g); m0: the numerical value of the mass of the empty crucible, unit: gram (g); b) determination of silicon carbide content: according to the standard specified in GB / T16555-2017, burn free carbon at 850 DEG C, then determine the total carbon content of the residue after 850 DEG C ignition to obtain the silicon carbide content in the sample, and use high-frequency infrared carbon and sulfur analyzer to measure the total carbon content of the residue after 850 DEG C ignition; ； ω(SiC): mass fraction of silicon carbide in the sample, %; ω (T.C * ): Total carbon content of the residue after ignition of the sample at 850°C, %; c) determination of SiO2, Al2O3, Fe2O3, TiO2 and CaO content: place the glass sheet of the sample to be tested on XRF fluorescence spectrometer, select pre-oxidation working curve, and obtain detection data after scanning, and calculate by using pre-oxidation calculation formula: ； ω(A x O y ): contents of various oxides in the sample; ω(R x O y ): oxide contents scanned by fluorescence pre-oxidation working curve; ω (Si02) * : amount of total silica in the sample, %: ω(SiO2): silicon dioxide content in the sample, %.

2. A chemical analysis method for detecting a carbon-containing silicon carbide refractory material according to claim 1, characterized by, The amount of potassium oxide and barium oxide obtained by high-temperature decomposition of the potassium carbonate and barium carbonate at 1100 DEG C is equal to the amount of potassium oxide and barium oxide obtained by reaction and decomposition of the potassium carbonate and barium carbonate.

3. The method of chemical analysis for detecting silicon carbide-containing refractory material according to claim 1, characterized by, The mass ratio of the anhydrous lithium tetraborate to the lithium metaborate is 67:

33.

4. The method of chemical analysis for detecting silicon carbide-containing refractory material according to claim 1 or 3, characterized by, The mass ratio of the mixture of the anhydrous lithium tetraborate and the lithium metaborate to the standard substance is 10:

1.

5. The method of chemical analysis for detecting silicon carbide-containing refractory material according to claim 1, characterized in that, The current of the spectrometer is set to 5-130 mA, the voltage is set to 10-40 kV, and the sampling time is set to 10 s-80 s.

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