JPS5981539A - Direct emission spectrochemical analyzer of molten metal - Google Patents

Abstract

PURPOSE:To analyze rapidly and directly each component contained in a molten metal sample in a production site by using an excited light focusing constitution from just above direction against the molten metal surface and a focusing tube constitution to which an opposing electrode and a focusing lense are provided. CONSTITUTION:The focusing lense 5 and the opposing electrode 8 whose top end 8' is near the lense 6 are fixed at lower end part of the focusing tube 2. Inner part of an emitting chamber 1 is fixed with gaseous Ar and is lowered by an elevator 24, and the gap between the end 8' and a bath surface is held to prescribed distance by a bath surface level sensor 10 and a controller 23 of gap between electrodes. An emitting device 29 is functioned to perform spark discharge between the end 8' and a molten metal 22 surface. The emitted light intensity is measured by a spectral detector 27, spectral beam intensity of each constituent is corrected by a calculator 28, and contained percentage of each constituent contained in the molten metal is obtained.

Description

[Detailed description of the invention]

This invention relates to a direct emission spectroscopic analyzer for molten molten roe, which spectrally analyzes the generated excitation light to directly determine the content of various components in the molten roe. For process control analysis in metal manufacturing, emission spectrometry is most commonly used for block samples fixed in a sand ring. However, for faster process control, there is a strong demand for the development of an apparatus that can directly analyze the molten state. There have been several attempts to perform direct emission spectroscopy of molten metal using electrical discharge, including the Iron and Steel International 52
(1979) 77-83 Negative and U.S. Patent No. 3,645,6
25.3,659,944, :i, 669,546. However, all of these can be said to be in the experimental stage. However, in order to be a direct analysis device for molten metal that can actually be put into practical use at manufacturing sites, it is necessary to

This is because there is no description of means for absorbing fluctuations in the intensity of excitation light due to changes in the spacing, or means for suppressing fluctuations in the optical axis during convergence of excitation light due to high heat, vibration, etc. The present invention was arrived at as a result of experiments and research on each of the above-mentioned means necessary for practical application, and the main components include an excitation light condensing configuration from directly above the molten metal surface, a counter electrode, and a condensing lens. This is a direct emission spectrometer for measuring molten gold by electrical discharge, which has a condensing tube configuration that is fixedly installed in close proximity to the molten metal. , an excitation light condensing lens provided above the tip of the counter electrode with its optical axis aligned with the tip of the counter electrode, an inert gas discharge hole around the condensing lens, and an inert gas discharge hole on the outer side. A lower circle t':;'i 'i'l with a lifting device and an inert gas blowing tube are installed, and a spectrometer entrance lens whose optical axis is aligned with the above-mentioned olfactory lens is fixed inside. 2 of the upper cylindrical tube, which has an inert gas passage hole around the entrance lens, a spectroscope is connected to the upper end, and the lower 14 part is inserted into the lower cylindrical tube. A condensing tube that is installed directly in a sealed shape consisting of two cylindrical tubes; There is an inert gas passage between the upper and lower ends, an opening facing the molten metal surface at the lower end, and a length around the lower part that allows the lower end to be immersed in the molten metal during measurement. a protective cylinder for the condenser tube, which has an air purifying cylinder provided with an inert gas outlet; and a spark light emitting device, which is connected between the counter electrode and the molten metal, respectively. This is a direct emission spectroscopy analyzer for molten metal characterized by comprising: In emission spectroscopic analysis using electrical discharge such as /Q-ri,
When the gap between the counter electrode tip and the metal sample surface changes, I+,'
I) It is necessary to maintain the gap between the electrodes at a constant value of 1/C in order to prevent the ri light intensity 1f from changing. When dealing with all solid block samples, it is easier to keep the gap between the electrodes constant, but when dealing with molten metal, the level of the molten metal varies and cannot be kept constant. Therefore, the lagoon]
Even if the Ifi level fluctuates, it is necessary to minimize the influence of the fluctuation on light collection. The inventor of the present invention learned from the following experiment that this problem can be solved by selecting a specific angle as the convergence angle of the excitation light to greatly alleviate and absorb the effects of fluctuations in the electric and negative gaps. In spark emission spectrometry analysis of a solid block sample, one beam is taken from an angle of 30 degrees to the sample surface, and in the US patent mentioned above, one beam is taken from an angle of 30 degrees or horizontally to the molten metal surface. Employs light focusing. The present inventor used an experimental device 6 capable of concentrating Snow ξ-reflection excitation light from various angles, and conducted experiments to find out in detail the relationship between the electrode gap and the excitation light intensity at each angle for iron. investigated. An example of the experimental results is shown in Figure 1 VC. In this figure, the horizontal axis shows the gap between the electrodes at each convergence angle (g), and the vertical axis shows the ratio of each spectral line intensity caused by each component in iron to the spectral line intensity of iron, and the total gap 2 The graph shows the rate of change in the intensity ratio when changing from .5 sm to 45 sm. In this figure, for example, srr 288.2 / Fe
l1271.4 K If you look at it, 8 of 288.2 nm
1 emission intensity of 271.4. When the intensity ratio to the intensity of Fe in nm is changed from 25 to 45 nm, the concentration ratio is 44 at 90 degrees, 128% at 60 degrees, and 3
At 0 degrees, it shows a change of 3C)4%. From the graph at each point in Figure 1, each component is 90% relative to the hot water level.
It has become clear that when light is focused from the vertical i9:5 direction, the entire layer is less affected by the inter-electrode gap. When the angle is set to ()Oo, it is easier to set the position of the light-emitting channels relative to the water surface in the actual device, compared to the case where the light is focused horizontally or at an angle of 30 degrees to the water surface. It is known that the angle setting can be performed reliably, and it is least susceptible to the effects of radiant heat from molten metal. Therefore, the device of the present invention directs the excitation light to a target facing the hot water surface.
The main configuration is one that focuses light at one position/n. Next, the present invention will be explained in detail with reference to FIG. 2, which shows an embodiment of the present invention. The device of this embodiment is installed vertically and is connected to the molten metal 22.
d'i A light emitting chamber 1 that applies a high voltage between the poles 8 to generate a spark or gas discharge, a light emitting device 29 that generates a high voltage, a condensing lens 6 that focuses the generated excitation light, and The excitation light is incident on the spectrometer entrance slit.
, Ck, and a calculator 28 that performs correction based on the spectral line intensity of IJ lux and calculation of the content rate from the intensity. The light emitting team 1 is the main part of the present invention, and is composed of a condenser tube 2, a protection cylinder 5, an atmosphere shielding tube 9, and the like. The condenser tube 2Vi consists of an upper condenser tube 4 and a lower condenser tube 3, the lower condenser tube 3 is made of a stainless steel ring that can conduct electricity, and the upper condenser tube 4 is made of Bakelite which is an insulating material. The upper end of the upper condenser tube 4 fli! I is fixed to the identified spectroscopic detector 27, and the upper end of the lower condenser tube 3 is slidably but airtightly inserted into the lower end of the upper condenser tube 4. Specifically, a lens 7 through which all of the excitation light is incident is fixed to a slit 26 provided at the entrance of the spectroscopic detector 27, and a gas passage hole 16 is provided around the lens 7. One of the lower condensing tubes 3 has a condensing lens 6 at its lower end, and a condensing lens 6 at its lower end.
A counter electrode 8 having a tip 8' is fixed on the optical axis of the condenser lens 6, and a gas discharge hole 7 is provided around the condenser lens 60. The original axis of the condensing lens 6 and the optical axis of the incident lens 7 are made to coincide. The condensing tube 2 is constructed as described above, and the level of the molten metal 22 changes drastically due to the condensing tube 2. Sometimes, only the lower condensing tube 3 is moved up or down in response to changes in the surface level.
The distance between the surface and the tip of the counter-Ih pole can be adjusted and controlled to a predetermined distance, and since the upper condenser tube 4 does not move, the distance between the input lens 7 and the spectroscopic detector 27 does not often change. Even if the surface level fluctuates widely, it will not affect the measurement and analysis accuracy of the spectroscopic detector. The counter electrode is a small electrode made of tungsten with a diameter of 3 m x 50 mm and is placed at the lower end of the lower condenser tube.
It should be installed so that '' is facing the hot water surface. Tsuchibe A tube 4 for injecting an inert gas such as Ar is installed near the upper end of the condenser tube 4, and the gas blown from this tube flows into the upper condenser tube 4 and the lower condenser tube 3. The interior is completely filled to create an inert atmosphere, the gas passage hole provided around the entrance lens 7 is energized, and the gas discharge hole provided around the condenser lens 6 is energized from the condenser tube opening. It blows out at high speed towards the area. This blown out inert gas advances into the atmosphere at the tip of the counter electrode and causes normal discharge, and the condenser tube 2
It also prevents the absorption loss of excitation light in the ultraviolet region within the lower condenser tube 3, and completely prevents contamination of the surface of the condenser lens 6 due to air cooling of the lower part of the lower condenser tube 3 and evaporated metal. An inter-electrode gap adjusting device 23 is attached to the upper part of the light tube 3, and by this, the gap between the hot water level and the tip of the counter electrode can be fully adjusted by moving the light condensing tube 3 up and down. The gap adjustment device 2; 3 is activated by the signal from the hot water level detector 13, and the gap is automatically adjusted to a constant gap.The lower condenser tube 3 is made of a stainless steel ring, so there is a counter electrode on the upper part. A terminal is provided so that current can be applied to the counter electrode through the lower condenser tube.This terminal and the sample electrode I2 immersed in the molten metal are connected to the light emitting device 29 by a high voltage cable. A protective cylinder 5 is provided on the outside, which encloses and protects the lower part of the condensing tube. The protective cylinder 5 is made of 31 tubes made of stainless steel ring 9, and a metal tube 1 for cooling medium such as air or water.
9 and discharged from pipe 2o to cool the protective cylinder and the inner region of the cylinder. The inner and outer walls of the cylinder 50 are coated with a fireproof material such as magnesia to provide heat resistance, and the tip of the counter electrode 8 attached to the lower condenser tube 3 is located at the lower end of the cylinder 5. However, this lower end is not suitable for radiant heat of molten metal or for photometry. In order to avoid excessive light, the opening 21 should preferably have a diameter of about 15 m. Since the gap between the tip of the counter electrode 8 and the hot water surface is usually 10 degrees or less during discharge (during foot measurement), the opening 21 is located close to the hot water surface. The inert gases such as A and R gases blown from the tubes 14 and 15 are blown out from the opening 21 and the air in and around the discharge point is discharged to form an inert gas that makes it easy to cause sparks and other discharges. atmosphere? ○Additionally, to the lower part 3' of the edge-retaining cylinder 5, attach a large-sized atmospheric shielding cylinder 9 with a length 61t' that allows the lower end to be immersed in the molten metal 22 during measurement. Therefore, the Ar gas blown out from the opening 21 is discharged into the atmosphere from the pipe 18 provided at the upper part of the atmospheric shielding tube 9 together with the air inside the atmospheric shielding tube 9, and the Ar gas is blown out from the opening 211\
An inert atmosphere is reliably maintained near the discharge area, and normal discharge can be carried out without air being drawn into the discharge area. In implementation, after mechanically removing the slag at the top by driving a refractory plate or the like, the chamber 1 is lowered to the removed area and the atmosphere shielding cylinder 9 is immersed in the hot water surface. There is no slag in 9 and normal discharge is possible. Even if some slag remains, the Ar gas blown out from the opening 21 will cause the opening 21 to
The remaining slag is removed from the atmosphere toward the atmosphere shielding cylinder 9, and there is no hindrance to electrical discharge of the molten metal. A hot water level sensor 10 connected to a hot water level detector 13 is attached to the lower part of the mining cylinder 5 to measure the hot water level k. This sensor may be an electrostatic sensor, a temperature sensor, or one that uses light or ultrasonic waves. The light emitting chamber 1 is held on a support base 25 and can be moved up and down by a lifting device 24. When analyzing molten metal using the apparatus of this embodiment, first, cooling water and Ar gas are flowed to fill the interior of the luminescence chamber 1 with iAr gas. Next, operate the elevator #24 to lower the channel 1 completely, operate the hot water level sensor 10 and the interelectrode gap adjustment device 23, and adjust the distance Iψ between the tip 8' of the counter electrode 8 and the hot water ih1 by 2~ It is maintained at a desired distance within a range of about 10 mm. Issue
The color device ff 297 is activated to generate a linear discharge at a frequency of about 200 to 800 fiz between the tip of the counter electrode 8 and the surface of the molten metal 22, and for the first 3 to 5 seconds, Luni is used as a preliminary discharge. After that, the luminescence intensity for about 5 to 10 seconds is measured by the spectroscopic detector 27, and it is
8. Correct the spectral line intensity of each component by taking the ratio of the spectral line intensities of all matrix components to find the ownership rate of each component contained in the molten metal □ Calculate the valley-containing components in the sample by sampling, etc. 4-ij of metals can be analyzed quickly and directly without complicated operations.
It is extremely useful and highly effective for operational management of smelting processes, etc.

[Brief explanation of drawings]

Fig. 1 is a graph showing an example of the experimental results regarding the condensing angle and the gap between the electrodes, which does not reach the luminescence intensity of the various components contained in the bath molten metal, and Fig. 2 is a graph showing an example of the result of the present invention. FIG. 2 is a longitudinal cross-sectional view of an example device. 1 is a luminous chamber, 2 is a condensing tube, 5 is a protective cylinder, 6 is a condensing lens, 7 is an incident lens, 8 is a counter electrode, 9 is an atmosphere shielding tube, 10 is a hot water level sensor, 22 is a molten metal , 23 is an electrode gap adjustment device, 24 is a Chan, S-lifting device, 27 is a spectroscopic detector, 28 is a content rate calculator, 29 is a light emitting device agent, patent attorney Masamitsu Akizawa, and 2 others.

Claims (1)

[Claims] (1) In the TtM section, a pair of electrodes with a small gap between the fd tip and the molten metal surface was installed, and an excitation electrode was placed above the tip of the counter electrode with the optical axis aligned with the tip of the 7" electric beam. The light condensing lens is equipped with a lower circular M1 tube that has an inert gas discharge hole around the condensing lens, a lifting device on the outside, and an inert tube (with an inert pipe attached). , is fixed inside the spectrometer entrance lens whose optical axis is aligned with the upper H self-condensing lens, has an inert gas passage hole around the entrance lens, and has a spectrometer at the upper end. connected, t'L, with a condensing tube provided vertically in a sealed manner consisting of two cylindrical tubes, an upper cylindrical tube whose lower end is inserted into the lower cylindrical tube; - The F part has an inert gas blowing pipe, the lower part has a hot water level detector, and the inert gas passage between it and the light tube. The condenser tube is equipped with an opening to open, a cylinder around the lower part has a length that allows the lower end to be fully immersed in the molten metal during measurement, and an atmosphere shielding cylinder with an inert gas outlet at the upper part. A light-emitting device connected between each of the eyelid cylinder and the molten metal; Metal 1st grade J
Nizura optical spectrometer.