JPS58102137A - Direct spectrochemical analyzer for molten metal with fine particle evaporation and carrying method - Google Patents

Abstract

PURPOSE:To permit accurate and rapid analysis in a position separated at a large distance by an apparatus wherein the molten metal is brought into the overheated state to generate ultrafine particles utilizing the evaporation action, which particles are fed to the analyzer together with the stream of inert gas. CONSTITUTION:A plasma arc or the like is irradiated to a molten metal 5 by a heater 3 in a fine particle generator 1 to bring it to the overheated state under still higher temperature, thereby to evaporate ultra fine particles. Inert gas is introduced from a gas inlet pipe 7 to produce a gas current rising through a cylindrical pipe 2. When the evaporated ultrafine particles are sent together with the stream of inert gas to an opening of a feed pipe provided as a double pipe outside of a heating source irradiating pipe 4, coarse particles are returned to the surface of the molten metal and only the fine particles are sent to an analyzer 29 via a distributor 14. Then, the fine particles are excited in a high-temperature plasma section 22 formed by a high-frequency generator 21 to emit a light, which is subject to spectrochemical analysis.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves irradiating the surface of a molten metal with a plasma ater@0 high-energy source to form a superheated field, which evaporates fine particles representative of the composition of the molten metal and leaves them. The molten metal is transported by an inert gas stream to an optical emission spectrometer, which has its origins in Gutsuma W/, which is installed at the site, and the content of various components in the molten metal is analyzed in real time. It is also 〇 regarding a direct emission spectrometer for metals.

In the metal manufacturing industry, emission spectroscopic analysis using an enclosure sample is most frequently used for quality control of products during process control of metal oil production. However, in recent years, as seen in the 41IK steel industry, online real-time processing has been developed for new smelting operations such as faster 1-manufacturing, 1-tube spotting or multi-stage refining. There is a strong need for the development of analytical methods for -im. Toret
``c#IIIA Direct analysis of metals is a method in which an electric discharge is caused between the molten metal and a counter electrode and the generated excitation light is measured with a spectrometer (A, Wittmann: Iro+1
and 5teel Int@r -national
, 52 (1979) P, 77-83), Zoyai 5-1 77) A method of directly measuring the excitation light emitted by irradiation with Russlede light using a spectrometer (excitation under inert gas: Japanese Patent Publication No. 11954- 7593, atmospheric excitation: E, F, Run
g*at ml: 8p@etrochimica
Aeta +l 22 (1966) P, 1678-16
80), or a method in which molten metal is pulverized using a special jet device using Ar gas and subjected to emission spectroscopic analysis (BI
SRmumuntzual R@port: 78 (19
66), 65.78 (1967), 35 (1968)
), research and development is being attempted using six methods.

However, these methods have so far been limited to the actual manufacturing site Vc
W& has never been put into practical use, and small-scale experiments within Ougendou have only been attempted for about 1 year.

To measure the actual performance of a direct analyzer for molten metals that can be put to practical use at manufacturing sites, we must first take into account the fact that the manufacturing site has a very poor measurement environment, such as vibrations and air pollution. Spectrometer.

Spectrometers, which are precision optical measuring instruments consisting of detectors for the intensity of each spectral line, are prone to trouble and malfunction under adverse measurement conditions such as those mentioned above. Must be installed separately. In order to perform component analysis by separating the molten metal and the spectrometer several tens of meters apart, there are two methods: one is to transmit excitation light generated by electrical discharge or radar irradiation, and the other is to pulverize the molten metal and transport it. However, the former has problems such as fluctuations in the optical axis due to vibration and high temperature, which hinders optical transmission, so the latter is more suitable. However, in the latter method, there is a problem that the pulverized sample remains attached to the tube wall during transportation. In the case of the above-mentioned cited document that adopts this method, the high flow rate
Since this method uses the spray action of gas flow to atomize molten metal, the particle size of the pulverized metal is 10
~ 100 Tsumugi @ odd or more, long distance OII due to large particle size
It is difficult to transport the particles, and due to the wide particle size distribution, there are problems such as loud fluctuations in emission intensity upon excitation and emission and poor analysis accuracy.

In view of these problems, the present invention has developed a method of further superheating molten metal and utilizing evaporation to generate noodle machine particles of about 0.1 μm or less, preventing adhesion and residue, and improving efficiency. We have conducted research and development focusing on transportation methods and methods of introduction into analytical equipment, and have provided a practical new analytical equipment that can be analyzed simply, quickly, and with high precision and sensitivity.

An embodiment of the device of the present invention is shown in the drawings.Hereinafter, the details of the device of the present invention will be explained with reference to the drawings. Particulate transport pipe 12, transport I
It consists of a gas distribution device 14 and an emission spectrometer 29 having a plasma Iq excitation source.

The particulate generating scissors 1111 is a part that functions to irradiate the bath molten metal with 5flCf plasma atomizer or the like to bring the molten metal into a superheated state at a higher temperature, and to evaporate the particulates representing the composition of the metal in a bell shape. A particulate generator 1 includes a cylindrical pipe for particulate generation 2. A heating source irradiation tube 4 connected to heating 1&1llt3 such as a plasma arc installed on the upper part facing the molten metal surface. Mold particle transport pipe opening part 11. The main body is the bell pipe/circular tube 6 with the inert gas introduction tube 7 attached, the heating device 30, and the counter electrode lO force! #Be done. The cylindrical tube 2 for generating fine particles is a cylindrical tube with a small diameter of 20 to 50-S degrees.
The bottom is horizontally open, and the molten metal surface is usually 10-
It will be installed with the following clearance. Boron nitride or! Refractory materials such as gnesia and alumina are suitable.

Heating device ili [3 is Glazma Arc, ah! , Snow's knees.

Electron beam or laser beam O heating sources could be applied, but in the case of plasma arc heating, the particle OH generation rate is fast, and the heating temperature is high, so components that are difficult to evaporate are easily evaporated. It was the most suitable. The heating source irradiation tube 4 connected to the heating device 3 is usually a circular tube with a small diameter of about 10 mm, and this is directly installed on the upper part of the cylindrical particle generation tube 20 facing the molten metal surface. The distance between the two was usually about 50 snow [0]. - The reason for setting it in the vertical position is to efficiently perform heating and evaporation of fine particles, and to efficiently introduce vaporized particles into the conveying pipe opening 11.
be. When the heating device is an f-plasma arc, a problem occurs when irradiating the molten metal surface at an oblique angle. When the plasma flame is reflected in the opposite direction from the metal surface, the evaporated particles ride on the flow of the plasma flame and spread, causing trouble in being taken into the conveyor tube opening 11. The irradiation tube 4 is transported to a conveying tube leg opening 11 which is installed as a concentric double tube with a narrow gap around the outer periphery of the irradiation tube 4. In the present invention, which aims at component analysis in molten metal, unlike the case where fine particles are simply collected, the entire amount of evaporated fine particles must be constantly and stably fed to the analysis scissors 29 together with the carrier gas at a constant flow rate. 6 In the present invention, a more efficient transportation technology for fine particles is required.
This prevents fine particles that evaporate from the metal surface and rise directly above from spreading to the surroundings, and also allows the particles to flow directly above the metal surface into the conveyor pipe opening 1.
We adopted a method of quickly creeping away on the flow of carrier gas flowing toward No. 1. When a plasma arc is used as a heating source,
The fine particles rise from the metal surface that has become overheated by the plasma arc, around the plasma flame, some diffuse to the surroundings, and some return to the metal surface. on the other hand,
The carrier gas introduced from the bottom of the cylindrical tube 2 for generating fine particles is irradiated from the heating source irradiation tube 4 because the outlet is not through the carrier tube opening 11 provided as a double tube around the heating source irradiation tube 4. A flow of inert gas is formed that enters the conveying pipe opening 11 from above the molten metal surface centered on the plasma flame generated by the molten metal. Therefore, the fine particles that have evaporated and ascended are drawn into the current and sent into the transport tube opening 11 at a constant dilution ratio. Therefore, as shown in the drawing, it is best to provide the conveyor tube opening 11 as a double tube outside the heating source irradiation tube 4, depending on the particle generation conditions, for example, in the case of plasma arc, voltage, current, Ar or Although it depends on the gas blowing flow rate of He @, it is better to make the transport tube opening 11 provided on the outer periphery of the heating source irradiation tube 4 a little shorter than the length of the heating source irradiation tube 4. ! lIi! ! l It is possible to return to the metal surface and transport only fine particles.

The evaporation rate and particle size of fine particles are influenced by the pressure of the evaporating atmosphere, the heating temperature, the type of atmospheric gas, etc. The particle size of the fine particles is particularly important as it has a large effect on the quantitative accuracy in emission spectroscopic analysis using a Goodsma excitation source, and it is essential to keep the particle size as small as possible and to adjust the particle size distribution. When the fine particles generated in molten steel by the device were examined using an electron microscope, the particle size was approximately 1 μm, although it depends on the generation conditions.
The following extremely fine particles with an average particle size of O, OS μm
The particle size distribution was narrow, with about 70% falling within the range of 0.04 to 0.06 particles, making it suitable for plasma emission spectroscopic analysis.

A bell pipe 9t6 made of fireproof material is attached to the outside 1i1 of the cylindrical pipe 2 for generating fine particles so as to have a double pipe structure. The open bottom of the rough pipe 6 is crushed into the molten metal 5 and sealed, and the inert gas blown in from the inert gas introduction w7 attached to the top is passed through the particulate generation cylindrical pipe 2i to the same cylindrical pipe 2. It serves to send the fine particles generated by evaporation into the transport tube opening 11. In addition, in many cases, slag exists floating on the surface of the molten metal, but the main tube tube 6 also functions to remove floating materials such as slag. It can be moved up and down, but first the #i pipe 6 is raised above the surface of the molten metal, and a large amount of inert gas is blown into the inlet pipe 7 to move the slag, or if the amount is large, it is removed by refractory material. The slag is moved by a mechanical method such as moving a plate made of molten metal over the surface of the molten metal, and immediately after that, the slag is transferred to the pipe 6.
lower it so that it is below the surface of the hot water. The slag, etc. that have been removed once will not flow into the rough tube 6, and there is a rough shielding tube that can keep the hot water surface directly below the heating source irradiation tube 4 free of slag and floating objects. If the tube 6 is not provided, the bottom of the cylindrical tube 2 for particle generation inside the tube must be immersed in neutralized molten metal to prevent the evaporated particles from coming out of the tube. The most important I of this book! This is a critical part and requires long-term durability.

Therefore, without directly immersing the cylindrical pipe 2#'i in the high temperature gas, the entire amount of fine particles evaporated from the surface of the molten metal is efficiently transferred to the transport pipe opening KIIIi, or into the cylindrical pipe 2. In order to prevent the direct inflow of the atmosphere and maintain an inert atmosphere inside the cylindrical tube 2 at all times, it is actually very important to provide a coarse strainer tube 6 outside the cylindrical tube 2 for generating fine particles.] K is essential. The particulate generators all were held on a refractory metal by, for example, being held by a cylindrical tube support 9 as shown in the figure.

The fine particles taken in from the conveyor pipe-mouth 11 are introduced into the gas v
The inert gas blown from 7 is placed on the gas and transported through the fine particle conveying pipe 12 to the gas distribution device 14.
When analyzing fine particles as in the present invention, the most important thing to do is to prevent fine particles from adhering to these inner surfaces of the KFi.
・Since the inside of the cylindrical pipe 2 for particulate generation and the transport pipe opening 11 are heated by the high heat of the gold metal, particulates tend to adhere to them.
1111 degrees decreases, making it more likely that residual adhesion will occur. As a result, fine particles in the carrier gas may move wildly or
It becomes impossible to obtain accurate analysis values. The evaporated fine particles are slow and quiet, and due to transport by f x jil K and a decrease in temperature, condensation among the fine particles and adhesion to the wall surface tend to occur. In addition, it has been found that fine particles once attached can be easily separated by blowing carrier gas at high speed within a short period of time after attachment, so the diameter of the conveyor tube 12 is as small as possible to increase the flow rate of the conveyor. As shown, it is necessary to adopt a method such as attaching a heating device 13 to keep heating at all times. Alternatively, it is effective to make the transport flow turbulent, such as by processing the inner surface of the transport pipe 12 or making the pipe 12 a turbulent line. Most of the residue could be prevented.

The particle transport pipe 12 is connected to a carrier gas distribution device 114.The carrier gas distribution device 114 diffuses the particles sent from the transport pipe 12 along with the gas in the space, and further homogenizes them into plasma. In order to obtain the optimum flow rate of the sulfur introduced into the transport section 22, a certain portion of the sulfur is discharged out of the system and the sulfur is distributed by the transporter, or during the transport, agglomeration progresses and becomes particularly coarse, resulting in 9 particles. The zero distribution device 114, which is a part that functions to perform particle sizing to send only fine particles to the plasma section 22 by excluding them from the system, is a small diameter cylindrical tube with a heating device 1113 attached to the outer periphery and is a fine particle transport pipe. 12 is inserted from the side wall, and the mold particle introduction tube 15 is installed vertically at a fixed interval from the top of the cylindrical tube so as to face the end of the conveying tube, and the flow rate is adjusted at the bottom of the cylindrical tube. 17 and nine discharge pipes 16 are attached. These three tubes are all 10■φ1! Coarse particles and distributed fine particles are discharged from the bottom discharge pipe 16 along with excess carrier gas, and the remaining fine particles are introduced into the introduction pipe 15 together with a constant flow rate of the carrier gas.

The particle introduction tube 15 is connected to the f-lasma excitation emission spectrometer 29.
connected to. The introduced fine particles are transferred to the introduction pipe 15 as shown in the figure. The plasma is carried into a triple tube plasma torch 20 consisting of a gas supply pipe 18 and a cooling gas supply 19, and reaches a high temperature plasma section 22 formed by the high frequency generator 1 [21] where it is excited and emitted. In the example, the mu r for the plasma is 1 to 151/wa, and the mu r for the cooling gas is 10 to 1,517 m.

The experiment was carried out by flowing the particle carrier gas at a flow rate of 0.5 to 147 m. The emission spectrum of the excited fine particles is collected by a condensing lens 23, separated by a spectroscope 24 consisting of a mirror 259 and a diffraction grating 26, and detected by a photomultiplier tube @27° component content calculation. Fitting #t28
The spectral line intensity of the sample is measured by this method, and the content of synthetic components in the analysis sample can be quickly determined. Although a high frequency inductively coupled emission spectrometer is most suitable for the analysis device 129 that excites fine particles to emit light, other types of arc discharge or glow discharge type plasma excitation emission spectrometer or atomic absorption spectrometer can be used. .

As explained above, according to the present invention, the components contained in a molten metal sample can be directly analyzed quickly and accurately in a sampling operation, and it is extremely useful for operating pipes 11 in metal refining processes, etc. Great effect.

[Brief explanation of the drawing]

The drawing is an explanatory diagram of an embodiment of the device of the present invention. 1: Particulate generator, 2: Cylindrical pipe for particulate generation, 3: Heating device, 5: Molten metal, 6: Shielding tube, 7: Inert gas introduction pipe, 10: Heating device 3
0 counter electrode, 12: Particulate transport pipe, 14: Carrier gas distribution device, 15: Particulate introduction pipe, 20: Plasma torch, 24
: Spectrometer, 29: Emission spectrometer with Gutsuzu 1 excitation source.

Claims (1)

[Claims] The bottom part is open near the Ilk metal surface, and the top part is
! Arc, ah! , slender, electron beam. A power supply connected to any heating device such as a radar
IkIllII irradiation tube and *m A closed cylindrical tube for generating fine particles, facing the metal surface, having an opening concentrically spaced from the outer periphery K11 of the tube, and attaching a fine particle transport tube thereto; The outer side of the cylindrical tube was immersed in the molten metal, the bottom part was immersed in the molten metal, and the upper part was fitted with a stainless steel inlet tube, and the bottom part was immersed in the metal.
A particulate generation number composed of a counter electrode i of a device such as Lasmear I. The distal end of the particle conveying tube 9 A conveyance distribution am consisting of a small number-shaped container equipped with a particle introduction tube to the light-emitting device and a discharge tube for excess conveyance f, the end of the particle introduction tube, high-frequency inductive coupling type. A direct emission spectroscopic analyzer for molten metals, which mainly consists of an optical emission spectroscopic analyzer consisting of a light-emitting device having an f-raz-rll origin such as plasma, a detector, etc.