GB2040750A - Molten metal sampler - Google Patents

Molten metal sampler Download PDF

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Publication number
GB2040750A
GB2040750A GB7939329A GB7939329A GB2040750A GB 2040750 A GB2040750 A GB 2040750A GB 7939329 A GB7939329 A GB 7939329A GB 7939329 A GB7939329 A GB 7939329A GB 2040750 A GB2040750 A GB 2040750A
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GB
United Kingdom
Prior art keywords
mould
molten metal
sampling
tube
bath
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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GB7939329A
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MINAS GERAIS SIDERURG
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MINAS GERAIS SIDERURG
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Publication date
Application filed by MINAS GERAIS SIDERURG filed Critical MINAS GERAIS SIDERURG
Publication of GB2040750A publication Critical patent/GB2040750A/en
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00Sampling; Preparing specimens for investigation
    • G01N1/02Devices for withdrawing samples
    • G01N1/10Devices for withdrawing samples in the liquid or fluent state
    • G01N1/12Dippers; Dredgers
    • G01N1/125Dippers; Dredgers adapted for sampling molten metals
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00Sampling; Preparing specimens for investigation
    • G01N1/02Devices for withdrawing samples
    • G01N1/10Devices for withdrawing samples in the liquid or fluent state
    • G01N1/14Suction devices, e.g. pumps; Ejector devices
    • G01N1/1409Suction devices, e.g. pumps; Ejector devices adapted for sampling molten metals

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  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Sampling And Sample Adjustment (AREA)

Abstract

The sampler consists of a pin- shaped glass or quartz mould (1) which is preferably at the centre of a cardboard tube (2), a refractory jacket (3) being provided between the cardboard tube and the mould. The mould may be a sealed vacuum tube (as shown). <IMAGE>

Description

SPECIFICATION Device for sampling molten metal Rapid and accurate knowledge of the chemical composition of a quantity of molten metal is a vital feature of the treatment of metal while in the liquid state.
In iron and steel works the assaying of samples from the bath to determine factors affecting the properties of the steel is a very important operation which has considerable advantages for subsequent steps.
Sampling procedures must meet certain conditions, such as being representative of the bath, sample reproducibility, feasibiiity, cheapness and ready operation.
Avariety of techniques have been devised for collecting samples from a molten metal bath and are still in use.
The most widely used sampling technique is to collect metal by means of a sampling spoon, the metal then being transferred to a cast-iron or steel mould. The same process is also used with refractory moulds. This fairly crude technique has a number of disadvantages. Samples are taken from the bath surface and are therefore not properly representative because of the heterogeneous nature of the complete bath, slag is collected as well as metal, and oxidation occurs during the step of transferring the sample to a mould.
The sample may be subjected to physical or chemical analyses. In physical analyses, where emission spectrometers, X-ray fluoroescence etc. are used, the samples have the shape of truncated cones or discs orthe like, while in chemical analyses the samples have a pencil shape.
There are two main sampling procedures - the direct method, in which the sampling device is introduced into the bath, and the method in which some liquid metal is separated from the bath in a sampling spoon, then removed from the bath.
Various kinds of sampling apparatus and methods are used. In the process in which a mould is filled from a sampling spoon, the latter is introduced manually into the bath and a quantity of liquid metal is collected. A deoxidant is added to the sample to prevent oxidation in the spoon, whereafter the sample in the spoon is transferred to a mould which is usually made of cast-iron.
This technique has many disadvantages. The sample starts to cool immediately on removal from the bath and the carbon/oxygen reaction may distort the analysis in relation to these two element, The presence of residual slag above the spoon modifies the conditions of equilibrium between the slag and the metal. The quantity of steel in the spoon may vary, as may also the quantity of aluminium used as deoxidant, so that the degree of stabilization ofthe sample varies.
Another sampling method uses a pump. The mould is introduced directly into the steel bath with a view to obviating the problems caused by deoxidation in the sampling spoon. Some aluminium must be introduced into the mould, and to prevent the entry of slag a lid or cover must be placed on the mould, then removed after the mould has passed through the slag. The lid can be made of board, so as to be reusable.
The disadvantages of this system are that the sample, being fairly dense, cools slowly and the need to cut it lengthens the assay time. Preparation and implementation are too dependent on the human factor, interalia as regards preparation of the mould, placing of the deoxidant, taking of the sample and mould release. The internal structure is affected by cooling, with the result of possible variations in emission spectrometry analysis, more particularly as regards the carbon.
In another kind of pump which is used conventionally, it is difficult to release the samples from the mould and preparation time is excessive. However, it is satisfactory in other ways. It is representative of the bath, samples suitable for analysis are obtained in 95% of cases, and the sample surface and dimensions are satisfactory so that a double analysis can be made and a miniature test tube can be made for the analysis of carbon, oxygen and nitrogen.
Unfortunately, sampling by these pumps is a slow process and handling is difficult.
Since 1962 the LD Steelworks and Ijmuiden has been using a third method which reduced the rate of reject samples from 20 to 13%. 100 seconds were saved and the totai time taken from extracting the sample to receipt of the results in the control room was reduced by 275 seconds.
In the vacuum tube method for sampling in a sampling spoon, a glass test tube is used in which there is a vacuum; when one of its specially prepared ends makes contact with the molten metal, the end breaks and a cylindrical specimen of approximately 3 mm diameter is sucked into the test tube.
This system has the advantage of rapid sampling and of analysis by a particular analyzer, mainly for carbon and sulphur.
Pyrolytic immersion sampler Because of the difficulties of sampling with a sampling spoon and with a pump, steelworks are going over to the use of pyrolytic immersion samplers, consisting of a mould fitted in a tube made of board or the like, the tube being secured to the end of a steel rod and introduced into the bath. This kind of sampling gives good representativeness since it is carried out inside the bath without contact with the air and without intermediate handling, so that there is no contamination nor loss of carbon.
Unfortunately, the kind of sample obtained has disadvantages, due to u nsatisf acto ry filling of the mould, unsatisfactory state of the mould surface, bubbles, micro-fissures etc.
There are two main factors governing sample quality - steel temperature and immersion time. If the steel temperature is too high, bubbles are formed, while if it is too low, filling of the mould is difficult. If the immersion time is too short, filling is unsatisfactory, and if it is too long the cardboard tube becomes covered in steel.
Control of speed, immersion depth and time and of steel temperature are important factors in this kind of sampling.
A steelworks which always uses this kind of sampling is thinking of satisfactory reproducibility, with minimum operator dependence. Samplers of this kind are usually made of steel and cost about 400% more than the device according to the present invention described below.
The steel to be sampled is often sucked by means of a manual pump fitted to the top end of the sampling device. A device such as pyrolytic sampler does not use a pump since it has a discoid mould in which there is a vacuum and which is extended in the shape of a peg or the like. After the sampling the disc is separated from the peg for measurements to be made in various items of apparatus.
These samplers, in addition to being expensive, have the disadvantage of sepa ration in the bottom of the tube below the discoid sample. This defect masks the result of the analysis and it often becomes necessary to analyze different parts of a single sample as a check on the values found.
The present invention provides a device for sampling molten metal for the purpose of assaying, which comprises a peg-shaped or narrow elongate mould made of glass or quartz or other material.
The device of the invention eliminates the separation described above and simplifies construction.
The sampler can be used for collecting liquid metal by immersion, meeting all the requirements of such a device up to the present since it is cheap, operates satisfactorily, gives satisfactory representation of the bath, makes reproducibility of sampling possible, ensures rapid and accurate analysis by conventional analysis processes and apparatus and can also be fitted to a mechanised system for immersion in the bath.
The accompanying drawing is a longitudinal cross-section through a device for sampling molten metal in accordance with the invention. The sample shown in the drawing has a glass tube 1 which also serves as a mould and which provides a peg-shaped or pin-like sample which is ideal for analysis by conventional and instrumental chemical processes.
The sample which the device according to this invention provides has a very good surface free from bubbles and slag contamination, is dense and needs no further preparation for analysis.
The tube used as the mould can be made of ordinary glass or of quartz and its internal diameter is preferably from 2 to 8 mm.
The tube can be of the capillary type open at both ends, via which it is pre-filled with molten metal as a result of ferrostatic pressure, or it can be a vacuum tube which gives better results as regards pre-filling.
To protect the glass tube while it is immersed in the liquid bath it is encased in a tube 2 which is made of cardboard and which is of greater diameter than the glass tube 1; the tube 2 is specially prepared and has specific properties for this kind of work.
An inner lining (3) between the glass and cardboard tubes serves for the protection and securing of the glass mould and can be made of a refractory substance such as plaster, cement, moulding sand orthe like; the lining has breathing ducts throughout its longitudinal extent which are parallel to the glass mould.
A fusible cap or plug or the like 4, which can be made of ordinary steel or aluminium or the like, depending upon the purpose for which it is to be used, is fitted to the rear end of the cardboard tube 2.
The thickness of the plug or the like 4 is such that it melts completely once the sampler has penetrated into the bath to the required depth. The plug 4 can be concave when the end of the glass mould is outside the limits of the protection provided by the cardboard tube 2 and the refractory substance 3, or it can be plane when the last-mentioned end is completely protected in the tube 2; this is a matter depending on the particular purpose for which the system is to be used.
The device is plunged into the metal bath in the direction indicated by an arrow in the drawing. The fusible plug 4, which melts only when the required sampling zone is reached, ensures that the rounded end of the glass mould 1 does not melt when it makes contact with the slag, for otherwise the plug 4 would melt prematurely and a non-representative sample would be collected.
The steel is sucked in by the vacuum existing in the mould 1 as far as the other end thereof, the steel then freezing in the shape of a pin or peg or the like.
The device according to this Utility Model can be introduced into the liquid bath mechanically or manually and the following factors should be observed: Rate of immersion; Depth of immersion; Duration of immersion; Bath temperature.

Claims (8)

1. A device for sampling molten metal for the purpose of assaying, which comprises a peg-shaped or narrow elongate mould made of glass or quartz or other material.
2. A device according to claim 1, wherein the peg-shaped mould is placed in a tube made of cardboard, coaxially therewith.
3. A device according to claim 2, wherein a refractory jacket is present between the glass mould and the cardboard tube by means of which the mould is secured in the tube.
4. A device according to any preceding claim, wherein the internal diameter of the mould is 2 to 8 mm.
5. A device according to any preceding claim, wherein the mould is a sealed vacuum tube.
6. A device according to claim 5, wherein the mould is tapered atone end and has a bulb at the other.
7. A device for sampling molten metal substantially as herein described with reference to the accompanying drawing.
8. A method of sampling molten metal which comprises immersing in the molten metal a device according to any preceding claim to fill the mould thereof with molten metal, withdrawing the filled mould and cooling it to provide a peg-shaped sample.
GB7939329A 1978-11-30 1979-11-13 Molten metal sampler Withdrawn GB2040750A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
BR5801704U BR5801704U (en) 1978-11-30 1978-11-30 METAL SAMPLING DEVICE IN FUSION

Publications (1)

Publication Number Publication Date
GB2040750A true GB2040750A (en) 1980-09-03

Family

ID=3955132

Family Applications (1)

Application Number Title Priority Date Filing Date
GB7939329A Withdrawn GB2040750A (en) 1978-11-30 1979-11-13 Molten metal sampler

Country Status (4)

Country Link
BE (1) BE880163A (en)
BR (1) BR5801704U (en)
FR (1) FR2443059A3 (en)
GB (1) GB2040750A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4624149A (en) * 1985-02-19 1986-11-25 Leco Corporation Sampling tube
US4643032A (en) * 1985-04-30 1987-02-17 Leco Corporation Frangible molten metal sampling device
US4995270A (en) * 1987-05-01 1991-02-26 Injectall Limited Molten metal sampling
CN107796666A (en) * 2017-11-13 2018-03-13 河钢股份有限公司 A kind of sampler and method of oxygen nitrogen hydrogen analyzer detection nitrogen content of molten steel

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4428245A (en) * 1981-03-31 1984-01-31 Nisshin Steel Company Limited Apparatus for sampling molten metal

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4624149A (en) * 1985-02-19 1986-11-25 Leco Corporation Sampling tube
US4643032A (en) * 1985-04-30 1987-02-17 Leco Corporation Frangible molten metal sampling device
US4995270A (en) * 1987-05-01 1991-02-26 Injectall Limited Molten metal sampling
CN107796666A (en) * 2017-11-13 2018-03-13 河钢股份有限公司 A kind of sampler and method of oxygen nitrogen hydrogen analyzer detection nitrogen content of molten steel

Also Published As

Publication number Publication date
FR2443059B3 (en) 1980-12-12
BE880163A (en) 1980-03-17
FR2443059A3 (en) 1980-06-27
BR5801704U (en) 1979-08-14

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)