A method for detecting metallurgical silicon by combining XRF and XRD

Abstract

The present invention relates to a method for detecting metallurgical grade silicon by combining XRF and XRD. This method detects the silicon content in the sample by establishing a working curve of XRF fluorescence for metallurgical grade silicon, and judges the silica content in metallurgical grade silicon based on the peak intensity of the XRD spectrum of metallurgical grade silicon. Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention shortens the inspection cycle of metallurgical grade silicon and improves work efficiency by using the working curve method of XRF fluorescence for metallurgical grade silicon. It solves the drawback that the chemical analysis method of metallurgical grade silicon in GB / T 14849 cannot distinguish the content of metallurgical grade silicon and silica.

Description

Technical Field

[0001] The present invention relates to a method for detecting metallic silicon in refractories for steel smelting, and specifically relates to a method for detecting metallic silicon by combining XRF and XRD. Background Art

[0002] Metallic silicon is usually added to refractory products to improve the high-temperature resistance, wear resistance, and oxidation resistance of the products. The inspection method is based on GB / T 14849 Chemical Analysis Methods for Metallic Silicon.

[0003] The national standard of industrial silicon GB / T 14849 stipulates that the content of oxide impurities in metallic silicon is detected by wet chemical method, and then the main content of silicon in metallic silicon is calculated by the subtraction method.

[0004] The advantages of this detection method are that the equipment is simple and can be detected in general laboratories that can perform wet chemistry.

[0005] The disadvantages of this detection method are as follows:

[0006] 1) The detection efficiency is not high, and different sample treatment methods are required for the quantitative analysis of each impurity element;

[0007] 2) It is difficult to quantitatively detect the content of silicon dioxide. If the content of silicon dioxide exceeds a certain range, it will not only affect the service life of refractory products, but also lead to buying unqualified metallic silicon raw materials at high prices;

[0008] 3) There are too many manual operation steps, and human errors will be introduced into the overall systematic error;

[0009] 4) Most of the data are manually calculated, which takes a long time, has low work efficiency, and large fluctuations in detection results.

[0010] In order to reduce the human factors in the detection of metallic silicon, improve the detection accuracy, shorten the inspection cycle, improve work efficiency, and distinguish silicon dioxide in metallic silicon, we combine the XRF method with XRD, achieving convenient operation, scientific and reasonable. Summary of the Invention

[0011] The present invention provides a method for detecting metallic silicon by combining XRF and XRD, which can accurately and quickly detect the content of metallic silicon by combining XRF and XRD, and can also be used to distinguish the content of silicon dioxide contained in metallic silicon.

[0012] In order to achieve the above object, the present invention is realized by adopting the following technical solutions:

[0013] A method for detecting metallurgical grade silicon by combining XRF and XRD. This method detects the silicon content in the sample by establishing a working curve of XRF fluorescence for metallurgical grade silicon, and judges the silica content in metallurgical grade silicon based on the peak intensity of the XRD spectrum of metallurgical grade silicon. The specific method includes:

[0014] 1) Detecting the silicon content in the sample by establishing a working curve of XRF fluorescence for metallurgical grade silicon:

[0015] a) Weigh standard samples with different silicon contents of the same mass, and then weigh the binder of the same mass. Put each weighed standard sample and a portion of the binder into an agate mortar and mix well. Press the standard sample mixed with the binder into a tablet, make a mark and reserve it for use;

[0016] b) Establish a working curve of metallurgical grade silicon on the XRF fluorescence spectrometer, and input the corresponding contents of Al2O3, CaO, and Fe2O3 in the standard samples with different silicon contents into the working curve; Set the parameters of the spectrometer current, voltage, detector, crystal, slit, sensitivity, and sampling time. Select the tablets with the highest detected contents of Al2O3, CaO, and Fe2O3 in the standard samples respectively, and perform scans at 2θ and PHD on the XRF fluorescence spectrometer. After determining the 2θ angle and the PHD range, register and detect the intensity of the elements in the order of the previously input standard samples;

[0017] c) Weigh an industrial silicon sample with the same mass as the standard sample, mix it with the binder of the same mass and then press it into a tablet. Place the industrial silicon tablet on the XRF fluorescence spectrometer, select the working curve for scanning, and then calculate the content of metallurgical grade silicon using the detection data. The calculation formula is: Subtract the contents of the three impurities of Al2O3, CaO, and Fe2O3 from 100 to obtain the content of metallurgical grade silicon;

[0018] 2) Judging the silica content in metallurgical grade silicon based on the peak intensity of the XRD spectrum of industrial silicon:

[0019] Diffract the industrial silicon sample using an XRD fluorescence diffractometer. The 2θ scanning angle is 15 - 70°, the tube current is 5 - 60 mA, the voltage is 10 - 40 kV, the step angle is 0.02 - 0.08 degrees / second, and the sampling time is 0.1 - 0.5 seconds; The main peak is for metallurgical grade silicon. If there are other peaks, which are the peaks of silica with a content of more than 2%, then judge this batch of metallurgical grade silicon as unqualified.

[0020] The number of standard samples is 6 - 10, and the weighing mass of the standard samples is 1 - 3 g.

[0021] The binder is one of boric acid, dextrin, starch, and carboxymethyl cellulose.

[0022] The tablet-making pressure of the sample in step 1) above is 10 - 60 tons.

[0023] In step 1)-b) above, the current is set to 5 - 130 mA, the voltage is set to 10 - 40 kV, the detector is (FPC, SC), the crystal is (Ge, LiF, PET, TAP), the slit is (High Res, Standard, High Sens), and the sampling time is 10 s - 80 s.

[0024] Equipment: XRF fluorescence spectrometer, XRD fluorescence diffractometer, press, agate mortar and mold;

[0025] Drugs: Standard substances of industrial silicon series, boric acid (analytical pure).

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] The present invention uses the XRF fluorescence working curve method for metallic silicon to shorten the inspection cycle of metallic silicon and improve work efficiency. It solves the drawback that the chemical analysis method of metallic silicon in GB / T 14849 cannot distinguish the contents of metallic silicon and silicon dioxide. Description of the Drawings

[0028] Figure 1 It is the intensity spectrum diagram (Al2O3) of the working curve of the XRF fluorescence spectrometer for industrial silicon in the embodiment.

[0029] Figure 2 It is the intensity spectrum diagram (CaO) of the working curve of the XRF fluorescence spectrometer for industrial silicon in the embodiment.

[0030] Figure 3 It is the intensity spectrum diagram (Fe2O3) of the working curve of the XRF fluorescence spectrometer for industrial silicon in the embodiment.

[0031] Figure 4 It is the spectrum diagram of the qualified industrial silicon after being scanned by the XRD fluorescence diffractometer.

[0032] Figure 5 It is the spectrum diagram of the industrial silicon containing more than 2% silicon dioxide after being scanned by the XRD fluorescence diffractometer. Detailed Embodiments

[0033] The following further describes the detailed embodiments of the present invention with reference to the drawings:

[0034] Embodiment:

[0035] (1) Establishment of the fluorescence working curve of metallic silicon:

[0036] As Figures 1 - 3 , six standard specimens with different contents are adopted, and the contents are shown in Table 1:

[0037] Table 1 (%)

[0038] Content\Serial number 1 2 3 4 5 6 <![CDATA[Al2O3]]> 0.026 0.032 0.375 0.24 0.705 0.79 CaO 0.055 0.06 0.111 0.34 0.145 0.79 <![CDATA[Fe2O3]]> 0.44 0.53 0.662 0.39 0.87 1.2

[0039] Weigh 1.5 g of each sample with a ten-thousandth balance, accurate to 0.1 mg. Then, using the same ten-thousandth balance, weigh 7 portions of 1.5 g of boric acid, accurate to 0.1 mg. Put each weighed standard sample and 1.5 g of boric acid into an agate mortar and mix well. Place the tablet press mold in the working position of the press. Put the well-mixed standard sample and boric acid into the tablet press mold and press into tablets under a pressure of 40 tons. After forming the tablets, make marks for future use. Establish a working curve for metallic silicon on the XRF fluorescence spectrometer, and input the corresponding contents of Al2O3, CaO, and Fe2O3 in the 7 standard samples into the working curve. The detection conditions for Al2O3, CaO, and Fe2O3 are set as shown in Table 2:

[0040] Table 2

[0041] Element name Current Voltage Detector Crystal Slit Sampling time <![CDATA[Al2O3]]> 70 mA 40 kV FPC PET Standard 30s CaO 70 mA 40 kV FPC LiF Standard 30s <![CDATA[Fe2O3]]> 70 mA 40 kV SC LiF Standard 30s

[0042] Select the samples with the highest contents of Al2O3, CaO, and Fe2O3 in 6 standard samples and perform scans on the XRF fluorescence spectrometer at 2θ and PHD. After determining the 2θ angle and PHD range, register the intensities of the detected elements in the order of the previously input standard samples. After verifying that the curve is linearly intact and performing matrix correction, use the standard samples for verification, and the error shall comply with the GB / T 14849 standard.

[0043] (2) Detect and calculate the content of metallic silicon in industrial silicon:

[0044] Weigh 1.5 g of a normally inspected industrial silicon sample with a ten-thousandth balance, accurate to 0.1 mg. Then, using the same ten-thousandth balance, weigh 1 portion of 1.5 g of boric acid, accurate to 0.1 mg. Put each weighed industrial silicon sample and 1 portion of boric acid into an agate mortar and mix well. Place the tablet press mold in the working position of the press. Put the well-mixed industrial silicon sample and boric acid into the tablet press mold and press into tablets under a pressure of 40 tons. Then place the tablets on the XRF fluorescence spectrometer, select the working curve for industrial silicon, upload the detected data to the company's quality management system after scanning, and then use the metallic silicon calculation formula to calculate with one key: Subtract the contents of the three impurities Al2O3, CaO, and Fe2O3 from 100 to obtain the content of metallic silicon. In the refractory material field, only the contents of Al2O3, CaO, Fe2O3, and metallic silicon are concerned.

[0045] (3) Use the XRD fluorescence diffractometer to scan and distinguish metallic silicon and silicon dioxide:

[0046] See Figure 4 、 Figure 5, using a special mold for XRD fluorescence diffractometer to make the industrial silicon into a diffraction sample (the industrial silicon is the same batch as the sample in step (ii) above). The 2θ scanning angle is 15 - 70°, the tube current is 30 mA, the voltage is 40 kV, the step angle is 0.02 degrees / second, and the sampling time is 0.2 seconds. The main peak is metallic silicon. If there are other peaks, and the peak intensity of silicon dioxide with a content of more than 2% can be clearly seen, then this batch of metallic silicon is a defective product.

[0047] Through multiple experiments and long-term data accumulation in the present invention, when the content of the by-product silicon dioxide entrained during the production of metallic silicon does not exceed 2%, it does not affect the use effect of the refractory products of the company. If silicon dioxide is added to the metallic silicon raw material and the disadvantages are detected using the GB / T 14849 standard to pass off inferior goods as good ones, it will cause segregation during the sampling of metallic silicon and silicon dioxide. The XRD fluorescence diffractometer can promptly detect the out-of-tolerance content of silicon dioxide.

[0048] Table 3 is the data comparison between the wet method and the fluorescence pressing working curve method for the detection of industrial silicon in the examples. It can be seen from Table 3 that the method of the present invention is basically consistent with the detection results of the conventional wet chemical method; Table 4 is the data reproducibility of the fluorescence pressing working curve method for the detection of industrial silicon in the examples. It can be seen from Table 4 that the method of the present invention has extremely small errors.

[0049] Table 3 Data Comparison between the Wet Method and the Fluorescence Pressing Working Curve Method for the Detection of Industrial Silicon

[0050]

[0051]

[0052] Table 4 Data Reproducibility of the Fluorescence Pressing Working Curve Method for the Detection of Industrial Silicon (Sample 3 Produced in the Northwest Region)

[0053] Once Fluorescent tablet 0.19 0.10 1.06 98.66 Twice Fluorescent tablet 0.20 0.09 1.05 98.66 Thrice Fluorescent tablet 0.20 0.08 1.06 98.66 Four times Fluorescent tablet 0.18 0.10 1.02 98.70 Range 0.02 0.02 0.04 0.04

[0054] Since the 2015 implementation, the metal silicon XRF fluorescence working curve method of the present invention has been regularly calibrated using wet methods and outsourced metal silicon samples, in addition to regularly checking the metal silicon working curve for drift. As shown in Table 1, the test results are within the error range of the parallel benchmark and meet the GB / T14849 standard. The fluorescence detection method and automated system utilize simple and fast one-click data extraction and one-click calculation functions. Testing industrial silicon using the GB / T14849 standard requires 12 hours of work, based on the preparation of six samples at a time. Furthermore, poor temperature control during the boiling of the sample to volatilize the metal silicon and silicon dioxide can easily cause splashing, which can affect subsequent testing processes and lead to significant deviations in the results. However, using the metal silicon XRF fluorescence working curve method, the entire process from weighing the sample, mixing the sample and boric acid mixture, scanning with the XRF fluorescence instrument, to one-click calculation of the results takes no more than two hours. Furthermore, the XRD fluorescence diffractometer can process the samples simultaneously, taking no more than two hours.

Claims

1. A method for detecting metallic silicon by combining XRF and XRD, characterized in that: This method is to detect the silicon content in the sample by establishing an XRF fluorescence working curve for metallic silicon, and to judge the silicon dioxide content in metallic silicon by the peak intensity of the industrial silicon XRD spectrum. The specific method includes: 1) Detect the silicon content in the sample by establishing an XRF fluorescence working curve for metallic silicon: a) Weigh the same mass of standard samples with different silicon contents, then weigh the same mass of binder, add one portion of each weighed standard sample to the binder in an agate mortar and mix thoroughly, press the standard sample mixed with the binder into a tablet, mark it, and set aside; b) Establishing a metallic silicon working curve on an XRF fluorescence spectrometer, entering the corresponding contents of Al2O3, CaO, and Fe2O3 in standard samples with different silicon contents into the working curve; setting the spectrometer parameters of current, voltage, detector, crystal, slit, sensitivity, and sampling time; selecting samples with the highest Al2O3, CaO, and Fe2O3 contents among the standard samples, and scanning them with 2θ and PHD on the XRF fluorescence spectrometer; after determining the 2θ angle and PHD range, registering and detecting the elemental intensities according to the previously entered standard sample sequence; c) Weigh an industrial silicon sample of the same mass as the standard sample, mix it with the same mass of binder, and press it into a tablet. Place the industrial silicon sample on an XRF fluorescence spectrometer, select the working curve for scanning, and then use the test data to calculate the metallic silicon content. The calculation formula is: subtract the three impurity contents of Al2O3, CaO, and Fe2O3 from 100 to obtain the metallic silicon content; 2) Determine the silicon dioxide content in metallic silicon by the peak intensity of the industrial silicon XRD spectrum: An industrial silicon sample was diffracted using an XRD fluorescence diffractometer with a 2θ scanning angle of 15-70°, a light tube current of 5-60 mA, a voltage of 10-40 kV, a step angle of 0.02-0.08 degrees / second, and a sampling time of 0.1-0.5 seconds. The main peak was metallic silicon. If there were other peaks, namely silicon dioxide peaks with a content of more than 2%, this batch of metallic silicon was judged to be unqualified.

2. The method for detecting metallic silicon by combining XRF and XRD according to claim 1, characterized in that: The number of standard samples taken is 6-10, and the weighing mass of the standard samples is 1-3g.

3. The method for detecting metallic silicon by combining XRF and XRD according to claim 1, wherein: The binder is one of boric acid, dextrin, starch and carboxylic acid cellulose.

4. The method for detecting metallic silicon by combining XRF and XRD according to claim 1, wherein: The tableting pressure of the sample in the above step 1) is 10-60 tons.

5. The method for detecting metallic silicon by combining XRF and XRD according to claim 1, characterized in that: In the above steps 1)-b), the current is set to 5-130 mA, the voltage is set to 10-40 kV, and the sampling time is set to 10s-80s.

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