JPH05223742A - Plasma emission analysis - Google Patents

Abstract

PURPOSE:To maintain an analysis accuracy and greatly reduce a time required for the analysis by measuring spectral intensity of a matrix element in a dissolution acid liquid of a metal sample and obtaining an element content from a spectral intensity ratio of an objective element to a matrix element when the intensity exceeds a specified value as a content of the dissolution liquid. CONSTITUTION:A dissolution acid liquid 5 of 1ml is added to a hole 4 of a sample 1. At the same time, the liquid 5 within the hole 4 via a suction capillary and a liquid to be inspected with a certain concentration (1g/100ml) are introduced into a plasma emission analysis device 7. After that, a spectral intensity of iron which is a matrix element is automatically monitored by a computer 8. Then, the spectral intensity of a target element and that of iron which is the matrix element are measured for three seconds after the spectrum of the iron exceeds 1g/100ml as a concentration of iron. The computer 8 calculates the content of the target element within steel by using the relationship between the intensity ratio which is obtained previously and a target element content, namely a calibration curve according to the spectral intensity ratio between the target element and iron.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma emission analysis method suitable for shortening the analysis time when a metal sample is analyzed by plasma emission analysis.

[0002]

2. Description of the Related Art In the process of producing a metal, it is very important to quickly measure the chemical composition of the molten metal during the refining process to control the refining and adjust the composition. Conventionally, various methods have been used to measure the chemical composition of molten metal rapidly, but most of them are physical analysis methods, and there is a problem in analysis accuracy.

On the other hand, the plasma emission spectrometry has high analytical accuracy and is widely used in research laboratories. However, since it is inferior in speed, it is difficult to use for analysis of chemical components of molten metal during refining process. The reason for this lack of swiftness is that it takes a long time to prepare a sample solution for plasma emission analysis. That is, for the sample solution, a sample of a minute piece is obtained from a metal test piece (target base material) by a drill, 1 g of the sample is accurately weighed, the weighed sample is transferred to a beaker, and a dissolving acid (hydrochloric acid, Add 20 ml of nitric acid, sulfuric acid, perchloric acid, etc., heat these to completely dissolve the sample, after complete dissolution, cool the solution, transfer the solution to a 100 ml volumetric flask and bring it to 100 ml with pure water. Accurately dilute this 1g / 100ml
The sample solution having the concentration of is transferred to a beaker, and is prepared through 8 steps.

In the plasma emission spectrometry, the sample solution thus prepared in the beaker is introduced into a plasma emission analyzer, the spectral intensity of the target element is measured, and the same operation is performed on the standard sample in advance. The prepared calibration curve is used to convert the content of the target element into the sample.

FIG. 6 shows a conventional plasma emission analysis situation. The beaker 9 prepared as described above.
When the suction thin tube 6 of the emission analyzer 7 is put into the sample solution 10 in the sample solution 10, the sample solution 10 reaches the plasma torch (not shown) through the thin tube 6, is excited to emit light in the plasma flame, and the spectral intensity is measured. Then, the computer 8 calculates the content of the target element in the sample.

For example, in FIG. 7, a minute piece is sampled with a drill from a cast sample obtained from molten steel (a truncated cone-shaped steel sample having a height of 50 mm, an upper surface diameter of 35 mmφ, and a lower surface diameter of 30 mmφ).
Accurately measure and dissolve acid solution (volume ratio of hydrochloric acid 2: nitric acid 1
8: 20 ml of water) was added and heated to completely dissolve the sample piece, the dissolved solution was cooled to room temperature, diluted to 100 ml with pure water, and transferred to a beaker. 2 shows the relationship between the time and the spectral intensity after the sample solution 10 in the beaker 9 was introduced into the plasma emission spectrometer 7 through the suction capillary 6.

[0007] Normally, pure water is introduced into the plasma torch (not shown) of the plasma emission spectrometer 7 through the suction capillary tube 6, and as shown in FIG. It takes, for example, 3 seconds to reach the plasma torch (not shown), and it takes, for example, 3 to 4 seconds to completely replace the pure water with pure water. Since it takes 6 to 7 seconds, for example, after the introduction of the sample solution, the spectral intensity of the target element is measured for 8 to 11 seconds. Calculated by computer 8. As shown in FIG. 7, the amount of sample solution consumed until such an analytical value is obtained is 0.
It is about 5 ml. As described above, the content rate of the target element in the sample can be obtained in an extremely short time after introducing the sample solution 10 into the plasma emission spectrometer 7. However, in order to prepare the sample solution, the above eight steps are required. However, it takes a long time of about 20 minutes.

By the way, in JP-B-63-52338, the step of accurately weighing 1 g of the above-mentioned sample piece is omitted, that is, a suitable amount of the sample piece of 0.5 to 2.0 g obtained above is used. A method for obtaining an analysis accuracy comparable to the above-mentioned conventional method and a fully automatic analyzer using this method have been proposed. The content of this analysis method is from 0.5 g / 100 ml
A solution with a sample concentration of 2.0 g / 100 ml was introduced into the plasma emission spectrometer, the spectral intensity of the target element and the spectral intensity of the matrix element were measured, and contained in the sample according to the calculation formula previously obtained from these intensity ratios. It is to be converted into a rate.

FIG. 8 shows the configuration of the fully automatic analyzer. Reference numeral 11 is a moving device for a sample container such as a rotating disk or a rack that can be moved sequentially, and 12 is a beaker containing an appropriate amount of sample pieces and a magnetic rotor. Reference numerals 13 to 16 are storage tanks for acids, reagent solutions, distilled water, etc., and a fixed amount of these is added into the beaker by the automatic quantitative addition device 17. Reference numeral 18 denotes a stirrer such as a magnetic stirrer, which accelerates the dissolution rate of the sample piece by stirring and at the same time makes the test solution in the beaker uniform.
Reference numeral 19 is a suction capillary, whereby the test solution is introduced into the solution emission analyzer 20, the spectral intensity of each element is measured, and the computer 21 calculates and outputs the analysis value. These operations are all automatically performed after the beaker 12 containing an appropriate amount of sample pieces is set on the disk or rack 11.

[0010]

However, even with such a technique proposed by Japanese Patent Publication No. 63-52338, it is necessary to dissolve at least 0.5 g, and in many cases 2.0 g of sample pieces in order to prepare a sample solution. It is not possible to obtain the effect of greatly shortening the solution preparation time. Therefore, it cannot be used to analyze the chemical composition of the molten metal during the refining process.

The present invention has been made in view of the above situation,
The present invention provides a plasma emission analysis method that can be used for analysis of chemical components of molten metal during refining process by significantly shortening sample solution preparation time and analysis time, while maintaining analysis accuracy. ..

The present invention includes (1) Japanese Patent Publication No. 63-52338.
In the method of determining the content rate of the target element in the sample based on the intensity ratio of the spectrum strength of the target element and the spectrum strength of the matrix element, which is disclosed in Japanese Patent Publication No. JP-A-2003-264, the sample solution concentration is 0.5 g / 100 ml to 2.0 g / 100 ml. It is possible to analyze even if it changes within the range of, and the spectral intensity of the target element and the spectral intensity of the matrix element when the spectral intensity of the matrix element becomes 0.5 / 100 ml equivalent intensity or more as the sample solution concentration. There is no problem in analysis accuracy by determining the content rate of the target element in the sample from the ratio. (2) Furthermore, in the above-mentioned conventional method, the amount of solution consumed by the analyzer is 0.5 ml until the analysis value is obtained. It was made focusing on the point that it is a degree.

[0013]

The summary of the present invention is as follows. (1) 0.5 to 5 ml of dissolved acid solution was added to the hole provided in the block-shaped metal sample, and the dissolved acid solution in which the metal sample was dissolved was introduced into the plasma emission spectrometer, and the spectral intensity of the matrix element was measured. Was measured, and from the intensity ratio of the spectral intensity of the target element and the spectral intensity of the matrix element when the spectral intensity of the matrix element became 0.5 g / 100 ml equivalent intensity or more as the sample solution concentration, A plasma emission analysis method, characterized in that the content is determined. (2) The plasma emission spectrometry method according to (1) above, wherein the amount of the dissolved acid solution added to the hole provided in the block-shaped metal sample is 1 ml. (3) From the intensity ratio of the spectral intensity of the target element and the spectral intensity of the matrix element when the spectral intensity of the matrix element becomes equal to or higher than the equivalent strength of 1 g / 100 ml as the concentration of the sample solution, the content ratio of the target element in the metal sample is determined. The plasma emission analysis method according to (1) or (2) above, which is characterized in that it is obtained.

[0014]

In the method of the present invention, the consumption of the dissolved acid solution is 0.5 ml or more necessary for analysis, for example, 1 ml, so that it is necessary to obtain the sample solution having the sample concentration (1 g / 100 ml) of the conventional method. The amount of dissolved sample pieces is 1/100 of the conventional value, 0.0
1 g (10 mg) is sufficient, which is extremely advantageous for dissolution. It should be noted that the minimum amount of consumption of the dissolved acid solution required for the analysis was 0.
If the amount is 5 ml, 0.005 (5 mg), which is 1/200 of the conventional amount, is more advantageous, and even if the upper limit amount of the dissolved acid solution is 5 ml, 0.05 g (50 mg), which is 1/20 of the conventional amount, is sufficient. , Is advantageous in terms of dissolution.

Further, in the method of the present invention, for example, 1 ml of the dissolved acid solution is added to the hole provided in the block-shaped metal sample. Therefore, for example, when a drill hole of 11 mmφ is provided,
The dissolved acid solution of ml is stored at a depth of 10 mm from the bottom of the drill hole, and the sample surface area in contact with the dissolved acid solution (sample surface area for dissolution) is about 3100 mm ² .

On the other hand, in the conventional method (method proposed by JP-B-63-52338), if a sample piece is modeled as a sphere having a diameter of 0.1 mm, the surface area of each sphere is about 0.03 mm ² , and the weight is steel. Then, it becomes 0.003 g. In order to dissolve 1g (0.5g) sample pieces with steel, about 300 pieces (about 150 pieces) of spheres with a diameter of 0.1mm are required, and the surface area at that time is about 10mm ² (about 5 mm ² ). Therefore, the dissolution surface area of the method of the present invention is about 300 times (about 600 times) that of the conventional method (the method proposed in Japanese Patent Publication No. 63-52338), which is extremely advantageous for dissolution.

Also, comparing the melting depths (from the surface), it is necessary to melt a sample of, for example, 10 mg in steel, whereas in the method of the present invention, about 0.4 μm should be melted, whereas in the conventional method. In the method proposed by JP-B-63-52338, 0.1 mm
It has to be dissolved in 50 μm, which corresponds to half the diameter, and the method of the present invention is about 100 times more advantageous in terms of dissolution.

[0018]

EXAMPLES Hereinafter, examples of analysis of chemical components of molten steel during the refining process by the method of the present invention will be described. (1) A cast sample 1 as shown in FIG. 1A is taken from the molten steel during the refining process. The diameter of the lower surface 2 of the sample 1 is 30 mmφ,
The upper surface 3 is an inverted truncated cone steel sample having a diameter of 35 mmφ and a height H of 50 mm. (2) As shown in FIG. 1 (b), the inverted truncated cone-shaped steel sample 1 is turned upside down and drilled from the small-diameter surface 2 of the sample 1 with a 11 mmφ drill.
Drill a hole 4 with a depth of mm. (3) Dissolved acid solution (mixed solution of hydrochloric acid 2: nitric acid 18: water 20 by volume ratio) in the hole 4 of the truncated cone-shaped steel sample 1 as shown in FIG.
1 ml of 5 is added. FIG. 2 shows how the amount of sample dissolved increases with the lapse of time after the addition of the dissolved acid solution.

(4) Simultaneously with the addition of the dissolved acid solution 5, the dissolved acid solution 5 in the hole 4 formed in the inverted truncated cone-shaped steel sample 1 is sucked through the suction thin tube 6 as shown in FIG. Concentration (1g /
When 100 ml) of the test solution 10 is introduced, it is introduced into the plasma emission spectrometer 7 having the spectral characteristics shown in FIG. (5) After introducing the dissolved acid solution 5 into the plasma emission spectrometer 7,
Calculate the spectral intensity of iron, which is the matrix element, by computer 8.
Automatically monitors and, as shown in FIG. 4, measures the spectral intensity of the target element and the spectral intensity of the matrix element iron for 3 seconds after the iron spectral intensity becomes equivalent to 1 g / 100 ml or more as the iron concentration. .. (6) From the spectral intensity ratio of the target element and iron, the computer 8 indicates that the relationship between the intensity ratio and the target element content determined in advance, that is, the calibration curve (for example, FIG. 5 shows the calibration when the target element is Al). Calculate the target element content rate in the steel.

Table 1 shows the results of quantifying each element in the molten steel and the average analysis time by the method of the present invention according to the above-mentioned procedures (1) to (6). In Table 1, the results of quantifying each element in the molten steel by the conventional method and the average analysis time are also shown. The conditions for carrying out the conventional method are as follows: The minute piece obtained in the procedure (2) for carrying out the method of the present invention is sampled, 1 g of this is accurately measured, and the dissolved acid solution (volume ratio of hydrochloric acid 2: nitric acid 18: water 20) is used.
Mixed solution of about 20 ml), heated and completely dissolved, the dissolved solution was cooled to room temperature, accurately diluted to 100 ml of pure water, transferred to a beaker, and placed in a plasma emission spectrometer as shown in FIG. From the measurement of the spectral intensity of the target element from 8 seconds to 11 seconds after introducing the sample solution shown in FIG.
This is a value obtained by calculating the sample content rate of the target element using a calibration curve obtained by a computer in advance by the same operation using a standard sample.

[0021]

[Table 1] As is clear from Table 1, the method of the present invention is compared with the conventional method,
It can be applied sufficiently in terms of analysis accuracy, and the time from the preparation of the cast sample to the calculation of the content rate can be quantified in about 80 seconds, which is about 1/20 as compared with the conventional method.

[0022]

As described above in detail, according to the plasma emission analysis method of the present invention, there is no need for special adjustment of the sample, weighing of the sample amount, complete dissolution of the sample, and a small amount of sample dissolution. , Analysis can be performed much faster than the conventional method and with the same accuracy as the conventional method. Therefore, in the refining of metal, it is possible to effectively adjust the components in the metal that change in time series.

[Brief description of drawings]

1A, 1B, and 1C are explanatory views of a procedure for preparing a sample solution.

FIG. 2 is an explanatory diagram of changes in the amount of sample dissolved.

FIG. 3 is an explanatory diagram of a plasma emission analysis situation.

FIG. 4 is an explanatory diagram of changes in spectrum intensity and dissolved acid solution consumption.

FIG. 5 is an explanatory diagram of an example of a calibration curve.

FIG. 6 is an explanatory diagram of a plasma emission analysis situation of a conventional method.

FIG. 7 is an explanatory diagram of changes in spectrum intensity and sample solution consumption in the conventional method.

FIG. 8 is an explanatory diagram of a configuration of a conventional fully automatic analyzer.

[Explanation of symbols]

 1 Cast Sample 2 Cast Sample Lower Surface 3 Cast Sample Upper Surface 4 Hole 5 Dissolved Acid Liquid 6 Suction Capillary 7 Plasma Emission Analyzer 8 Computer

Claims (3)

[Claims] 1. A hole formed in a block-shaped metal sample has 0.5 holes.
~ 5 ml of the dissolved acid solution was added, and the dissolved acid solution in which the metal sample was being dissolved was introduced into a plasma emission spectrometer, and the spectral intensity of the matrix element was measured. 0.5 g / 100
A plasma emission spectrometry method, characterized in that the content ratio of a target element in a metal sample is obtained from the intensity ratio of the spectrum intensity of the target element and the spectrum intensity of the matrix element when the intensity becomes equal to or higher than ml. 2. The plasma emission spectrometry method according to claim 1, wherein the amount of the dissolved acid solution added to the hole provided in the block-shaped metal sample is 1 ml. 3. The inclusion of a target element in a metal sample from the intensity ratio between the spectrum intensity of the target element and the spectrum intensity of the matrix element when the spectrum intensity of the matrix element becomes 1 g / 100 ml equivalent intensity or more as a sample solution concentration. 3. The plasma emission analysis method according to claim 1, wherein the rate is obtained.