JPS62239052A - Analysis of silicon in iron or steel - Google Patents

Abstract

PURPOSE:To quickly and easily analyze silicon by dissolving a silicon-contg. iron or steel sample in an acid, adding an ammonium molybdate to the soln. to form a silicomolybdic acid complex and analyzing the same by a flow analysis method. CONSTITUTION:The silicon-contg. iron or steel sample is dissolved in the acid and the sample soln. 1 thereof is passed through a valve 3 and is fed to a capillary 8 in a hot bath vessel 9. The ammonium molybdate 7 is fed through a capillary 6 to the sample soln. and is brought into reaction at about >=50 deg.C hot bath temp. to form the molybdic acid complex. A disturbance suppressor (oxalic acid, etc.) for phosphorus and arsenic is passed through a capillary 10 and is mixed with the molybdic acid complex to decompose the molybdic acid complex of the phosphorus and arsenic. A reducing agent 13 is passed through a capillary 12 and is mixed wit the sample soln. to form a molybdenum blue complex. The absorptivity is measured by an absorption photometer 15 by which the silicon is analyzed. Since the measurement is made by the flow analysis method in the above-mentioned manner, the time for the measurement is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an analytical method that can easily and quickly measure the silicon content in steel.

[Prior Art] A method for quantifying silicon in iron and steel specified in JIS G1212 is generally adopted as a method for analyzing silicon in steel.

This method involves dissolving iron and steel samples in acid, filtering them, adjusting the volume, taking a portion of the sample, adding ammonium molybdate solution to it, and leaving it for 10 minutes to form a silicomolybdate complex. After this, an oxalic acid solution is added to remove interference from phosphorus and arsenic, and a ferrous ammonium sulfate solution is added to measure the absorbance of the resulting molybdenum blue complex to determine the amount of silicon.

In carrying out this method for quantifying silicon, the current situation is that sample separation, addition of reagents, etc. have traditionally been carried out manually.

On the other hand, in Japanese Patent Publication No. 60-61646 (flow injection analysis method), an indicator and sample are added to the carrier liquid in the middle of a series of flow paths, and the acid concentration in the sample is detected colorimetrically. A branch technique for conducting acid concentration analysis is disclosed.

[Problems to be solved by the invention] By the way, while the means for analyzing many impurity elements in steel have been speeded up by analysis using instruments, the analysis of silicon has been carried out using the wet chemical method described above. It has been pointed out that the method is based on an analytical method and lacks speed and simplicity. That is, the above-mentioned method requires a series of complicated operations such as fractionating the sample solution and adding reagents, which requires skill and makes it difficult to carry out rapid analysis.

Therefore, in response to the above-mentioned circumstances, the present invention focuses on the above-mentioned absorbance flow analysis method, and by applying this, provides an analysis method that can measure the silicon content in steel more quickly and easily than before. was created with the purpose of

[Means for Solving the Problems 1] The present invention provides a method for analyzing silicon by spectrophotometric flow analysis after dissolving a silicon-containing steel sample in an acid, filtering it, and making it to a constant volume. A sample solution and an ammonium molybdate solution were injected and mixed into a thin tube that was allowed to flow, and the thin tube was passed through a hot water bath to form a silicon molybdate complex. After that, a phosphorus and arsenic interference inhibitor and a reducing agent were added to the thin tube. The present invention relates to a method for analyzing silicon in steel, characterized in that silicon is analyzed by sequentially injecting and mixing silicon molybdic acid complexes and measuring the absorbance of the resulting silicon molybdic acid complexes.

[Operation] A flow path showing the basic concept of the present invention is shown in FIG. 1, and the flow path will be explained below in accordance with the order of reaction.

First, a steel sample containing silicon is dissolved in an acid, filtered, and a sample solution 1 made up to a constant volume is introduced into the sample loop 2.

This sample loop 2 is connected via a valve 3 to a thin tube 5 through which a carrier solution 4 is flowing, and by switching the valve 3, a fixed amount of the sample solution 1 is injected into the carrier solution 4 and mixed.

The sample solution 1 injected into the capillary 5 contains the capillary 6 and the capillary 5.
Since ammonium molybdate 7 in the capillary tube 6 is injected and mixed into the capillary tube 5 and introduced into the capillary tube 8 after the connection, the capillary tube 8 is heated in the hot water bath 9. During this time, a silicon molybdic acid complex is formed.

Since the thin tube 8 that passed through the hot water bath 9 is connected to the thin tube 10, this silicomolybdic acid complex is contained in the thin tube 10.
The phosphorus and arsenic interference inhibitor 11 is injected into the thin tube 8.
When mixed, the phosphorus and arsenic molybdenum complexes are decomposed.

Further, the capillary 10 is connected to a capillary 12, and this capillary 1
The reducing agent 13 in 2 is injected into the thin tube 10 and mixed, and the silicon molybdate complex is reduced while flowing through the connected thin tube 14 to become a molybdenum blue complex.

Finally, silicon in the steel can be quantitatively analyzed by measuring the absorbance of the molybdenum blue complex with an absorbance photometer 15 installed in the middle of the flow of the thin tube 14.

Here, in mixing the acidic sample solution 1 and the ammonium molybdate solution 7, if the concentration of the ammonium molybdate solution 7 is 5% or more, precipitation of molybdic acid will occur in the capillary tube B and the capillary tube 8 will be clogged. The concentration should be below, preferably 3 to 5%.

Furthermore, the thin tube 8 is heated in a hot water bath 9 to generate a silicon molybdic acid complex, but if the heating temperature is 50°C or higher, the reaction will proceed almost 100%.
It is necessary to set the temperature to 0°C or higher, and it is more desirable to set the temperature to 50 to 80°C.

In addition, warm bath 411! ! The length of the thin tube 8 in 9 is preferably long in order to complete the reaction, but if it is too long, the absorbance obtained will be low, so it is necessary to make it an appropriate length. .

Oxalic acid or hydrofluoric acid is generally used as an interference inhibitor for phosphorus and arsenic, and ferrous ammonium sulfate or ascorbic acid solution is generally used as a reducing agent for the silicon molybdic acid complex.

Further, the thin tube 14 must have a length sufficient to complete the reduction reaction of the silicon molybdic acid complex.

[Example] Using the absorption high flow analysis flow path shown in FIG. 1, a sample solution was continuously measured in a circular motion.

This sample solution contains pure iron (silicon content = 0.001
wt%) silicon in 0.5g, 0.01wt%, 0.1w
t% equivalent was added, and 20 ml of hydrochloric acid was added. Hydrogen peroxide solution 10m
1 was added and dissolved, and then diluted to 100ml.

In addition, the sample solution injection amount, reagent solution, each liquid composition or reagent concentration, and each reagent flow rate are as shown in Table 1, and the one corresponding to capillary tube 8 in FIG. 1 is 5 m, and the one corresponding to capillary tube 14 is as shown in Table 1. 3 m, and the water bath temperature was set at 55°C.

As a result, an absorbance peak as shown in FIG. 2 was obtained approximately 3 minutes after injection of the sample solution.

The repeatability coefficient of variation is 5.2% and 0.7%, respectively.
, and almost the same accuracy as the conventional method was obtained.

When the analysis method according to this example was performed on the same sample in parallel with conventional wet chemical analysis, it was found that 40 minutes was sufficient for 12 sample solutions, whereas the conventional method required 90 minutes. Ta.

That is, it has become possible to perform the operations after sample decomposition in about half the time required compared to the conventional method.

[Effects of the Invention] As described above, the present invention dramatically shortens the time required for analyzing silicon in steel. This makes it possible to analyze using an extremely simple method that only requires injecting the amount into the device.

Table 1

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a flow path showing the basic concept of the present invention;
The figure is a graph showing the measurement results of an absorptiometer, with time on the horizontal axis and absorbance on the vertical axis. l...Sample solution 2...Sample loop 3...
Valve 4...Carrier solution 5...Tube 6.
...Tube 7...Ammonium molybdate 8...
Thin tube 9... Hot water bath 10... Thin tube 11... Phosphorus and arsenic interference inhibitor 12... Thin tube 13... Reducing agent 14... Thin tube 15... Spectrophotometer l... Sample solution 2...Sample loop 3-...
...Valve 4...Carrier solution 5...Thin tube 6
...tubule 7... ammonium molybdate 8.
... Thin tube 9... Hot water bath io... Thin tube 1
1... Phosphorus and arsenic interference inhibitor 12... Capillary 1
3... Reducing agent 14... Capillary 15... Absorption photometer Figure 2 Absorbance time (minutes)

Claims (1)

[Claims] In a method of analyzing silicon by spectrophotometric flow analysis after dissolving a silicon-containing steel sample in acid, filtering it, and bringing it to a constant volume, the sample solution and ammonium molybdate solution are injected into a capillary tube through which a carrier solution flows.・After mixing and passing the capillary through a hot water bath to generate a silico-molybdic acid complex, a phosphorus and arsenic interference inhibitor and a reducing agent are sequentially injected and mixed into the capillary, thereby producing a silico-molybdic acid complex. A method for analyzing silicon in steel, characterized by analyzing silicon by measuring the absorbance of .