A method for determining the sulfur blank value in flux

Abstract

The present invention belongs to the field of chemical analysis, and particularly relates to a method for determining a sulfur blank value in a flux. The method comprises the following steps: S1, weighing a specific mass of flux, placing the flux into a crucible, placing the crucible in the analysis position of a carbon-sulfur analyzer, and operating the carbon-sulfur analyzer to obtain a sulfur blank value; S2, repeating S1 several times to obtain sulfur blank values ​​corresponding to fluxes of different masses; S3, fitting a linear equation Y=aX+b, with the flux mass as the abscissa X and the sulfur blank value as the ordinate Y; S4, assuming the flux mass X=0, the corresponding Y value is the sulfur blank value of the flux. This method can eliminate interference in determining the blank value caused by sulfur leaching out of the crucible during the measurement process, thereby obtaining a more accurate sulfur blank value for the flux.

Description

Technical Field

[0001] The invention belongs to the field of chemical analysis, and in particular relates to a method for determining a sulfur blank value in a flux. Background Art

[0002] Currently, carbon-sulfur analyzers, based on the principles of high-frequency induction combustion and infrared absorption, are the most common method for measuring sulfur. This process requires the use of a flux; the sulfur impurity in the flux is released during the measurement process, contributing to the sulfur blank value. Therefore, the sulfur blank value is a crucial indicator for flux products. The lower the sulfur blank value, the better.

[0003] Current flux preparation technology cannot reduce the flux's sulfur blank value to zero, meaning that residual sulfur remains in the flux. During the analysis process, sulfur is released, resulting in a sulfur blank value that interferes with sulfur measurement in the sample. Therefore, a lower sulfur blank value is more beneficial for sulfur measurement in the sample. The sulfur blank value S of commercially available fluxes is approximately 0.0005%, though some flux varieties may be labeled with even lower values. The sulfur blank value is a key indicator of flux product quality, and accurately measuring it is of practical significance. Currently, there are two methods for measuring the sulfur blank value: 1. The standard addition method: This involves adding a known amount of a standard substance to a crucible, followed by the flux, and measuring the sulfur value under analytical conditions. This method can result in negative blank values ​​and is therefore inapplicable because the measured and referenced values ​​are significantly greater than the blank value. 2. The direct measurement method: This method involves adding only the flux to the crucible without adding a sample and simulating analytical conditions to measure the sulfur content, which is the blank value. However, this method lacks consideration of sulfur release from materials such as the crucible. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a method for determining the sulfur blank value in a flux, which can eliminate the interference of sulfur leached out of the crucible on the blank value determination during the measurement process, and the obtained sulfur blank value is more accurate.

[0005] The present invention provides a method for determining a sulfur blank value of a flux, comprising the following steps:

[0006] S1, weigh a specific mass of flux, put it into a crucible, place the crucible in the position to be analyzed of the carbon-sulfur analyzer, run the carbon-sulfur analyzer, and obtain the sulfur measured value;

[0007] S2, repeat S1 several times to obtain the sulfur values ​​corresponding to fluxes of different masses;

[0008] S3, with flux mass as the horizontal coordinate X and sulfur measured value as the vertical coordinate Y, the linear equation Y=aX+b is obtained by fitting;

[0009] S4, take the flux mass X=0, and the corresponding Y value is the sulfur blank value of the flux.

[0010] In the present invention, in the linear equation Y=aX+b, Y is the measured sulfur value (unit: ppm); the intercept b is the sulfur blank value of the flux; the slope a represents the change in sulfur leaching when a certain crucible and a certain flux are used in combination; and aX represents the amount of sulfur leached out of the crucible under X grams of flux.

[0011] In a preferred technical solution provided by the present invention, the mass interval of the different flux masses is 0.50 grams. It is well known that when a certain amount of sample is melted in a high-frequency induction furnace with a certain mass of flux, the sample is burned and the sulfur therein is completely released. The flux is generally added in an amount of 1 to 3 grams. Therefore, the mass increment intervals of 0.50, 1.00, 1.50, 2.00, 2.50, and 3.00 grams are appropriate, and the workload is appropriate, while the amount of sulfur released is within the detection limit of the instrument.

[0012] In another preferred technical solution provided by the present invention, the mass interval of the fluxes of different masses is less than 0.50 g. The above mass interval is suitable for fluxes with relatively high sulfur blank values.

[0013] In a preferred technical solution provided by the present invention, the determination method specifically includes the following steps:

[0014] S1, weighing multiple groups of the same flux of a specific mass, placing them into corresponding crucibles, placing the crucibles in the position to be analyzed on the carbon-sulfur analyzer, running the carbon-sulfur analyzer, and obtaining the sulfur measured value;

[0015] S2, repeat S1 several times to obtain the sulfur values ​​corresponding to multiple groups of fluxes with different masses;

[0016] S3, with flux mass as the horizontal coordinate X and sulfur measured value as the vertical coordinate Y, the linear equation corresponding to different groups of flux is fitted to obtain Y=aX+b;

[0017] S4, take flux mass X = 0, and the corresponding Y value is the sulfur blank value of different groups of flux;

[0018] S5, add the sulfur blank values ​​of different groups of flux and divide by the number of groups to obtain the average sulfur blank value of the flux.

[0019] In the above preferred technical solution provided by the present invention, the sulfur content result is averaged, thereby eliminating the influence of accidental factors on the sulfur content measurement.

[0020] In another preferred technical solution provided by the present invention, the determination method specifically includes the following steps:

[0021] S1, weighing multiple groups of the same flux of a specific mass and placing them into corresponding crucibles, with different groups of flux using different types of crucibles; placing the crucibles in the analysis position of the carbon-sulfur analyzer, running the carbon-sulfur analyzer, and obtaining the sulfur measured value;

[0022] S2, repeat S1 several times to obtain the sulfur values ​​corresponding to multiple groups of fluxes with different masses;

[0023] S3, with flux mass as the horizontal coordinate X and sulfur measured value as the vertical coordinate Y, the linear equation corresponding to different groups of flux is fitted to obtain Y=aX+b;

[0024] S4. Select the linear equation with the smallest slope a from the linear equations corresponding to different groups of fluxes. In this linear equation, the flux mass X=0, and the corresponding Y value is the sulfur blank value of the flux.

[0025] In the above preferred technical solution provided by the present invention, the linear equation with a small slope corresponds to a small crucible leaching rate, and the sulfur leaching amount under the same test conditions is small, the sulfur leaching interference is small, and it is more conducive to the measurement of sulfur blank value.

[0026] In a preferred technical solution provided by the present invention, the crucible is an ultra-low sulfur crucible. The ultra-low sulfur crucible has very little sulfur dissolved in it, and the measured sulfur blank value is more accurate.

[0027] In a preferred technical solution provided by the present invention, the carbon-sulfur analyzer uses oxygen with a purity of ≥99.999%. The purity of ordinary oxygen is usually ≥99.2%, while high-purity oxygen contains less impurity sulfur, making the measured sulfur blank value more accurate.

[0028] Compared with the prior art, the method for determining the sulfur blank value in the flux provided by the present invention has the following beneficial effects:

[0029] Since the amount of sulfur released by leaching in the crucible is positively correlated with the mass of the melt, the interfering sulfur released by the crucible will be reduced by reducing the amount of flux. When the amount of flux approaches zero infinitely, the amount of interfering sulfur released by the crucible will also approach zero infinitely, thereby eliminating the interference of sulfur leaching out of the crucible on the determination of the sulfur blank value in the flux. Based on the above technical concept, the method provided by the present invention first uses a carbon-sulfur analyzer to detect crucibles with different masses of flux added, and then fits a linear equation Y=aX+b with the flux mass as the horizontal coordinate and the sulfur measurement concentration as the vertical coordinate. Finally, the Y value corresponding to the flux mass X=0 is taken as the sulfur blank value of the flux. This method eliminates the interference of sulfur released by the crucible, measures the sulfur blank value of the flux itself, overcomes the defects in the existing method of measuring sulfur blank value, provides a new solution for the determination of flux blank value in the sulfur analysis process, and also provides a practical method for determining sulfur blank value in flux production.

[0030] Furthermore, in the method provided by the present invention, aX in the linear equation Y = aX + b represents the sulfur leaching outflow. Therefore, the method provided by the present invention also provides a practical solution for measuring the sulfur leaching outflow of a crucible. The lower the sulfur leaching outflow, the less interference the crucible's sulfur impurities will have on the analysis process, indicating better crucible quality. Therefore, the method provided by the present invention can also be used to determine the quality of a crucible. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0032] Figure 1 Schematic diagram of flux mass-sulfur measurement values ​​in Example 1 of the present invention;

[0033] Figure 2 Schematic diagram of flux mass-sulfur measurement values ​​in Example 2 of the present invention;

[0034] Figure 3 Schematic diagram of flux mass-sulfur measurement values ​​measured in a common crucible in Example 3 of the present invention;

[0035] Figure 4 Schematic diagram of flux mass-sulfur measurement values ​​measured using a special crucible for carbon and sulfur analysis in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0037] In the following embodiments of the present invention, the carbon-sulfur analyzer used is a CS844ES carbon-sulfur analyzer manufactured by LECO Corporation of the United States, and the key condition parameters are as follows: (1) Analysis Time (Analysis Time, the time when sulfur is analyzed, the time when sulfur is released under combustion conditions), standard mode: 40 seconds, ES mode (enhanced sensitivity mode): 130 seconds; (2) Cycle Time (Cycle Time, including the time when the crucible enters the equipment + the purification system time + the analysis time + the time when the crucible leaves the equipment after analysis, that is, the time taken for the entire analysis process of one crucible), standard mode: 130 seconds, enhanced sensitivity mode: 270 seconds; (3) Carrier Flow (Carrier Flow), standard mode: 3 liters / minute, enhanced sensitivity mode: 0.8 liters / minute; unless otherwise specified, the purity of the oxygen used in the operation of the carbon-sulfur analyzer is ≥99.999%.

[0038] Example 1

[0039] The determination of the sulfur blank value of pure iron flux and the amount of sulfur leached out of the crucible caused by 2.0 g of flux are as follows:

[0040] Weigh the pure iron flux shown in Table 1 and put it into a crucible, which is then placed in the position to be analyzed on the carbon and sulfur analyzer.

[0041] Press the run button and the carbon-sulfur analyzer will automatically run (the impurity sulfur content in pure iron flux is relatively high, so use the standard mode of the carbon-sulfur analyzer for measurement); the result will be automatically output in ppm to obtain the sulfur measured value;

[0042] Continuously measure and obtain the sulfur values ​​corresponding to different qualities of flux;

[0043] With flux mass as the horizontal coordinate X and sulfur measured value as the vertical coordinate Y, use EXCEL to fit into a linear equation, the result is: Y = 0.3331X + 5.902, such as Figure 1 As shown;

[0044] Take X=0, and the corresponding Y value is the sulfur blank value, and the result is: Y=5.90ppm.

[0045] 2.0 g of flux is added during sample measurement. Therefore, the amount of sulfur leached out of the crucible caused by the 2.0 g flux needs to be measured for accurate deduction when measuring the sample; the amount of sulfur leached out aX=Yb=6.45-5.90=0.55 ppm; that is, the amount of sulfur leached out of the crucible caused by the 2.0 g pure iron flux is 0.55 ppm.

[0046] Table 1 Flux quality of pure iron flux - sulfur measurement value table

[0047] Flux mass / g 0.50 1.0 1.50 2.00 2.50 3.00 Sulfur measurement value / ppm 6.13 6.25 6.37 6.45 6.70 7.01

[0048] Example 2

[0049] The determination of the sulfur blank value of the tungsten granular flux and the amount of sulfur leached out of the crucible caused by 1.5 grams of flux are as follows:

[0050] Weigh the tungsten granular flux shown in Table 2 and put it into a crucible, which is then placed in the position to be analyzed on the carbon and sulfur analyzer.

[0051] Press the run button and the carbon-sulfur analyzer will automatically run (the impurity sulfur content in the tungsten flux is low, so the carbon-sulfur analyzer needs to be measured in enhanced sensitivity mode); the result will be automatically output in ppm to obtain the sulfur measured value;

[0052] Continuously measure and obtain the sulfur values ​​corresponding to different qualities of flux;

[0053] With flux mass as the horizontal coordinate X and sulfur measured value as the vertical coordinate Y, use EXCEL to fit into a linear equation, the result is: Y = 0.0589X + 0.1687, such as Figure 2 As shown;

[0054] Take X=0, and the corresponding Y value is the sulfur blank value, and the result is: Y=0.17ppm.

[0055] 1.5 grams of flux is added during sample measurement. Therefore, the amount of sulfur leached out of the crucible caused by 1.5 grams of flux needs to be measured so that it can be accurately deducted when measuring the sample. The amount of sulfur leached out is aX=Yb=0.26-0.17=0.09ppm; that is, the amount of sulfur leached out of the crucible caused by 1.5 grams of tungsten particle flux is 0.09ppm.

[0056] Table 2 Flux quality of tungsten granular flux - sulfur measurement value table

[0057] Flux mass / g 0.50 1.0 1.50 2.00 2.50 3.00 Sulfur measurement value / ppm 0.20 0.23 0.26 0.28 0.30 0.36

[0058] Example 3

[0059] Quality comparison between ordinary crucibles and crucibles specially designed for carbon and sulfur analysis

[0060] (1) Measure the amount of sulfur leached out of an ordinary crucible, as follows:

[0061] Weigh the tungsten-tin-iron flux shown in Table 3 and put it into a crucible, which is then placed in the position to be analyzed on the carbon-sulfur analyzer.

[0062] Press the run button and the carbon-sulfur analyzer will automatically run (the blank value of the impurity sulfur in the tungsten-tin-iron flux is relatively high, so use the standard mode of the carbon-sulfur analyzer to measure); the result will be automatically output in ppm to obtain the sulfur measured value;

[0063] Continuously measure and obtain the sulfur values ​​corresponding to different qualities of flux;

[0064] With flux mass as the horizontal coordinate X and sulfur measured value as the vertical coordinate Y, use EXCEL to fit into a linear equation, the result is: Y = 0.2537X + 4.2127, such as Figure 3 As shown;

[0065] Take X = 0, the corresponding Y value is the sulfur blank value, the result is: Y = 4.21ppm;

[0066] 2.0 grams of flux was added during the sample measurement. Therefore, the amount of sulfur leached out of the crucible caused by the 2.0 grams of flux needed to be measured for accurate deduction when measuring the sample; the amount of sulfur leached out aX=Yb=4.68-4.21=0.47 ppm; that is, the amount of sulfur leached out of the crucible caused by the 2.0 grams of tungsten-tin-iron flux was 0.47 ppm.

[0067] Table 3 Flux quality when using ordinary crucible - sulfur measurement value table

[0068] Flux mass / g 0.50 1.0 1.50 2.00 2.50 3.00 Sulfur measurement value / ppm 4.35 4.50 4.55 4.68 4.87 4.99

[0069] (2) Measure the amount of sulfur leached out of the crucible dedicated for carbon-sulfur analysis as follows:

[0070] Weigh the tungsten-tin-iron flux shown in Table 4 and put it into a crucible, which is then placed in the position to be analyzed on the carbon-sulfur analyzer.

[0071] Press the run button and the carbon-sulfur analyzer will automatically run (the blank value of the impurity sulfur in the tungsten-tin-iron flux is relatively high, so use the standard mode of the carbon-sulfur analyzer to measure); the result will be automatically output in ppm to obtain the sulfur measured value;

[0072] Continuously measure and obtain the sulfur values ​​corresponding to different qualities of flux;

[0073] With flux mass as the horizontal coordinate X and sulfur measured value as the vertical coordinate Y, use EXCEL to fit into a straight line equation, the result is: Y = 0.1954X + 4.2113, such as Figure 4 As shown;

[0074] Take X = 0, the corresponding Y value is the sulfur blank value, the result is: Y = 4.21ppm;

[0075] 2.0 grams of flux was added during the sample measurement. Therefore, the amount of sulfur leached out of the crucible caused by the 2.0 grams of flux needed to be measured for accurate deduction when measuring the sample. The amount of sulfur leached out aX=Yb=4.56-4.21=0.35 ppm; that is, the amount of sulfur leached out of the crucible caused by the 2.0 grams of tungsten-tin-iron flux was 0.35 ppm.

[0076] Table 4 Flux quality when using a special crucible - sulfur measurement value table

[0077] Flux mass / g 0.50 1.0 1.50 2.00 2.50 3.00 Sulfur measurement value / ppm 4.31 4.44 4.50 4.56 4.66 4.85

[0078] It can be seen that 2.0 g of tungsten-tin-iron flux causes the amount of sulfur leached out of the ordinary crucible to be 0.47 ppm, and the amount of sulfur leached out of the special crucible for carbon-sulfur analysis to be 0.35 ppm; therefore, when measuring the test sample, the special crucible for carbon-sulfur analysis has less interference and is more conducive to sulfur measurement.

[0079] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for determining the sulfur blank value in a flux, characterized in that: The following steps are involved: S1, weigh a certain mass of flux, put it into a crucible, place the crucible in the position to be analyzed of the carbon-sulfur analyzer, run the carbon-sulfur analyzer, and obtain the sulfur measured value; S2, repeat step S1 several times to measure and obtain the sulfur values ​​corresponding to fluxes of different masses; S3, with flux mass as the horizontal coordinate X and sulfur measured value as the vertical coordinate Y, the linear equation Y=aX+b is obtained by fitting; S4, take the b value in the linear equation as the sulfur blank value of the flux.

2. The determination method according to claim 1, characterized in that The mass interval of the fluxes of different masses is 0.50 gram.

3. The determination method according to claim 1, characterized in that The mass interval of the fluxes of different masses is less than 0.50 gram.

4. The determination method according to claim 1, characterized in that The following steps are involved: S1, weighing multiple groups of the same flux of a certain mass, placing them into corresponding crucibles, placing the crucibles in the analysis position of the carbon-sulfur analyzer, running the carbon-sulfur analyzer, and obtaining the sulfur measured value; S2, repeating step S1 several times to obtain the sulfur values ​​corresponding to multiple groups of fluxes with different masses; S3, with flux mass as the horizontal coordinate X and sulfur measured value as the vertical coordinate Y, the linear equation corresponding to different groups of flux is fitted to obtain Y=aX+b; S4, take the b value in the linear equation corresponding to different groups of flux as the sulfur blank value of different groups of flux; S5, add the sulfur blank values ​​of different groups of flux and divide by the number of groups to obtain the average sulfur blank value of the flux.

5. The determination method according to claim 1, characterized in that: The following steps are involved: S1, weighing multiple groups of the same flux of a certain mass and placing them into corresponding crucibles, with different groups of flux using different types of crucibles; placing the crucibles in the analysis position of the carbon-sulfur analyzer, running the carbon-sulfur analyzer, and obtaining the sulfur measured value; S2, repeating step S1 several times to obtain the sulfur values ​​corresponding to multiple groups of fluxes with different masses; S3, with flux mass as the horizontal coordinate X and sulfur measured value as the vertical coordinate Y, the linear equation corresponding to different groups of flux is fitted to obtain Y=aX+b; S4. Select the linear equation with the smallest slope a from the linear equations corresponding to different groups of fluxes, and take the b value in the linear equation as the sulfur blank value of the flux.

6. The determination method according to claim 1, characterized in that: The purity of oxygen used in the operation of the carbon-sulfur analyzer is ≥99.999%.

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