WO2011047846A1

WO2011047846A1 - Device for taking slag samples

Info

Publication number: WO2011047846A1
Application number: PCT/EP2010/006403
Authority: WO
Inventors: Walter Jeroen Vortrefflich; Wilhelmus Engelbertus Heijne
Original assignee: Danieli Corus Bv
Priority date: 2009-10-22
Filing date: 2010-10-20
Publication date: 2011-04-28

Abstract

The invention relates to a device for taking slag samples from a converter or other container with molten metal and slag, the device having a sample chamber for receiving a slag sample with an inlet opening and a slag cooling element, wherein the slag cooling element extends from the inlet opening into the sample chamber over at least half the length of the sample chamber.

Description

DEVICE FOR TAKING SLAG SAMPLES

The invention relates to a device for taking slag samples from a container with a molten metal and slag, the device having a sample chamber for receiving a slag sample with an inlet opening and a slag cooling element.

Taking slag samples from a liquid metal, such as iron or steel by means of a probe is well known in the art. However, this relates to taking slag samples from a container such as a vessel or a channel in which the slag on the liquid metal has such composition and related viscosity that the slag can easily flow into a sample chamber provided in a sample probe. Taking slag samples from a converter is different from all other slag sampling because of the special conditions in a converter and because of different properties of slag in a converter. This makes it far more difficult to take a slag sample. In a converter molten iron from a blast furnace together with scrap iron and steel are mixed by injecting oxygen by means of an oxygen lance with great force into the liquid metal and slag. The carbon content of the iron is removed by the oxygen reacting with the carbon in the iron to form carbon monoxide and carbon dioxide. In this environment the slag is continuously in motion, contains gaseous enclosures and has in general poor fluidity which makes it hard to take a slag sample if possible at all with the existing slag probes. In practice a slag sample from a converter is taken by stopping or interrupting the oxygen injection, tilting the converter after which a sample is taken manually. This procedure of stopping the oxygen injection, tilting of the converter, taking the slag sample manually, returning the vessel in the original position and resuming the oxygen injection takes several minutes which means quite a loss in terms of production time and production costs.

In US 6,370,973 a sample probe for a sub-lance is disclosed that should be suitable to take a slag sample from among others a converter. This known sample probe has a sample chamber with an inlet channel that is smaller than the diameter of the sample chamber and far smaller than the diameter of the sub-lance probe in which the sample chamber is provided. A cooling element needed to freeze the slag is provided at the top of the sample chamber.

It is an objective of the present invention to provide a device for taking slag samples that allows to take sufficiently large samples in a reliable manner.

It is another objective of the present invention to provide a device for taking slag samples that allows to take samples in an automated or semi-automated manner.

It is another objective of the present invention to provide a device for taking slag samples that can be produced at low costs as part of a sub-lance system. One or more of these aspects are realized by providing a device for taking slag samples from a container with a molten metal and slag, the device having a sample chamber for receiving a slag sample with an inlet opening and a slag cooling element, wherein the slag cooling element extends from the inlet opening into the sample chamber. A serious problem with taking slag samples from a converter is that the slag because of poor fluidity will not flow into a sample chamber with a small inlet channel as used in taking slag samples from for instance pig iron. For that reason the sample chamber has to have a large inlet opening. With a sample chamber with a sectional area which is determined by the inner sectional area of the probe used with the sub-lance system to take a sample, the size of the inlet opening is in the range of at least half of that sectional area to equal to the sectional area of the sample chamber. However, with a large inlet opening it is a problem to keep the slag in the sample chamber. By providing that the slag cooling element extends from the inlet opening into the sample chamber part of the slag coming into the sample chamber almost immediately cools to or to below the temperature at which the slag solidifies. The cooling element is a metal element, for instance a steel element with sufficient mass to cool the slag to below the solidification point and to prevent it from melting during sampling. The term extending from the inlet opening is meant to comprise that the cooling elements extends either from a distance outside or inside the inlet opening or from exactly the inlet opening.

According to a further aspect of the invention the cooling element extends from the inlet opening over at least half the length of the sample chamber in order to be able to get and hold a sufficient amount of slag in the sample chamber. This is further improved by providing that the cooling element comprises two or more sections. With two sections, the sections can be positioned opposite to each other in the inlet opening and the sample chamber and with more than two sections the sections can be positioned along the inner perimeter of the inlet opening and the sample chamber.

According to a further elaboration of the invention at least part of a section extends across the inlet opening and/or the sample chamber. With this embodiment the section extends across the inlet opening and/or the sample chamber over part or the total length of the section into the sample chamber. Extending across the inlet opening and/or the sample chamber means that a section extends from one side to another side or with a circular inlet opening and/or sample chamber from one point to another point on the inner circumference, which in neither case has to be the largest distance. According to still a further embodiment it is provided that the cooling element comprises two intersecting sections. With this embodiment the section are flat or bend plates that both have a slit which allow to slip the sections into each other. A practical embodiment has two intersecting sections at a straight angle at the point of intersection. Although other configurations with more sections and at other angles are possible, this will result in a too complicated and therewith too expensive cooling element.

According to still a further aspect of the invention it is provided that at least one section of the cooling element has a stepped part. Such a stepped part is for example the side of a section that runs from an outer point or a central point of a section in a direction from the inlet opening into the sample chamber and which is provided with successive horizontal and vertical steps as seen when the device is submerged vertically with a sub-lance into the converter. The horizontal parts in the cooling element when the device is in use not only cool the slag but also provide an immediate anchoring point for the slag. The anchoring point serves to give support during the solidifying of the slag and to prevent the slag from exiting the probe.

According to another embodiment the cooling element is provided with a further plate parallel to the plane of the inlet opening of the sample chamber. This further plate helps to prevent the slag from flowing out of the sample chamber when lifting the sub-lance with slag probe out of the converter. This is also due to the extra cooling surface provided by the plate. The size of the plate is chosen dependent on the total free surface area of the inlet opening.

A further embodiment provides a connecting member to connect sections of the cooling element with each other. Such a connecting member consist of several separate sections between the sections of the cooling element or a single section connecting all sections of the cooling element. According to a further embodiment the connecting member is positioned in the inlet opening, which can be against the inner side of the inlet opening or at a distance from said inner side. The connecting member not only helps to keep the sections of the cooling element in position it also helps to cool, solidify and support the slag. When placed against the inner side of the inlet opening it also helps to prevent that the rim of the wall forming the inlet opening burns away directly because of the elevated temperatures in the slag. This is particularly important when the wall is made of paper or cardboard as with most sub-lance probes.

In order to facilitate the inflow of slag into the sample chamber the sample chamber is provided with one or more openings at a distance from the inlet opening. These openings prevent that air or other gaseous media get entrapped in the sample chamber and also allows that after an initial fill of the sample chamber through the inlet opening an additional fill at a level above the inlet opening may take place. In this manner it is ensured that sufficient slag will be collected for analysis thereof.

According to a preferred embodiment the sample chamber has a cylindrical shape with opposite of each other a closed end and an open end, wherein the open end is the inlet opening. The sample chamber is provided with at least one further opening in the wall of the sample chamber between the inlet opening and the closed end of the chamber. With this embodiment the sample chamber and inlet opening ic formed by the outer end of a paper tube as commonly used with all kinds of probes for a sub-lance system. The closed end of the sample chamber is made up by a heat resistant body, such as for instance a sand body.

In order to keep the components of the device together the cooling element and the heat resistant body are connected to each other. According to a further embodiment this is achieved by providing a further paper tube which fits into the paper tube making up the wall of the sample chamber and wherein the heat resistant body is clamped in the further tube or clamped between the cooling element and the further tube and wherein the cooling element is attached to the further tube. These three components can than be pushed as a unit into the outer paper tube with the largest diameter after which the inner tube can easily be fastened to the outer tube by means of for instance staples.

The device for taking slag samples according to the invention is further elucidated on hand of the example shown in the drawing, in which:

fig.1 shows part of a probe with the device in cross-section,

fig.2 shows a section according line A-A in fig.1 ,

fig.3 shows a section according line B-B in fig .1 ,

fig.4 shows a section according line C-C in fig .1 ,

fig.5 shows a longitudinal view and a bottom view of the heat resistant body, and fig.6 shows a longitudinal view and a bottom view of the further paper tube.

In fig.1 a cross-section of an example of a device for taking slag samples 1 is shown. The device comprises an outer paper tube 2 as commonly used for various probes for a sub-lance system. These paper tubes are available in different lengths, however the paper tube for the device preferably has a maximum length of 2000 mm. The paper tube 2 has a certain standard outer diameter and wall thickness and therewith a certain inner diameter which determines the diameter of the sample chamber 3. Preferably, the outside diameter is not less than 75 mm and not more than

80 mm. The sample chamber has an inlet opening 4 which is also determined by the inner diameter of the outer paper tube 2. At the opposite side of inlet opening 4 the sample chamber 3 is provided with a heat resistant body 5 which forms the closed end of the sample chamber 3. The heat resistant body 5 is a baked sand-resin material or can be made of a refractory or ceramic material.

In the sample chamber 3 a cooling element 6 is provided which has two flat sections 7,8 that intersect at a right angle to each other. Both sections 7,8 are provided with a slit in the middle which allows to slide the sections into each other. See also fig.4 for a cross-section of cooling element 6. Another possible embodiment is to use four sections that extend from the wall of the sample chamber 3 to the centre line thereof and weld the sections together.

The flat sections 7,8 extend across the inner diameter of outer paper tube 2 at and near the inlet opening 4. At a distance from the inlet opening 4 the sections have a stepwise cut-out with vertical and horizontal steps 9,10 (when in use) ending with straight end parts 1 1. In particular the steps 10 which are horizontal when in use offer support for solidified slag.

The straight end parts 1 1 extend along the sand body 5. The sand body 5 is provided with slits 12 to receive the end parts 1 1 , see fig 5 for a longitudinal view and a section of sand body 5. See also fig.3 for a cross-section with end parts 1 1 and sand body 5.

A further paper tube 13 is provided which fits in the outer paper tube 2. The paper tube 13 is connected with sand body 5 and cooling element 6. The paper tube 13, sand body 5 and cooling element 6 can then be pushed as a unit in the outer tube 2 and subsequently fixed in the proper position.

The sand body 5 has a two part form with a first cylindrical part 14 that fits in the paper tube 13 and a second cylindrical part, a collar 15 with a diameter corresponding with the inner diameter of the outer paper tube 2. The depth of the slits 12, that receive the end parts 1 1 , is such that the bottom of the slits 12 is in line with the outer side of the first cylindrical part 14 of sand body 5.

The inner paper tube 13 is provided with slits 16 to receive the last part of the end parts 1 1. The inner paper tube 13 is positioned with respect to sand body 5 so that the slits 12 in sand body 5 correspond with the slits 16 in the inner paper tube 13. With the sand body 5 clamped between cooling element 6 and inner paper tube 13 or clamped in the inner paper tube 13, the cooling element 6 is fixed to the inner paper tube 13 by means of for instance staples. In this way a unit is formed that can be pushed in the outer paper tube 2 and fixed thereto, for instance also by means of staples that connect inner and outer paper tubes 2, 13.

At the inlet opening 4 the cooling element 6 is provided with a connecting member 17 that is a further connecting means between the sections of the cooling element. The connecting member 17 has an annular form and is positioned against the inner wall of the outer paper tube 2. The connecting member forms an extra cooling means and protects the inner edge of the paper tube 2 from burning away immediately when the probe is submerged in the slag.

In the centre of the inlet opening 4 a plate 18 is provided which is directly connected to the sections 7,8 of cooling element 6. In this example plate 18 has a circular shape but could also have other shapes. The surface area of plate 18 is dependent of the inner diameter of the outer tube 2.

The thickness of the sections of cooling element 6, connecting member 17 and plate 18 is such that these are thick enough not to melt when submerged into the slag and that there is sufficient mass for the necessary cooling capacity. A thickness in the range from 1-5 mm and more preferably from 2-4 mm have shown to give satisfying results. With a width in one of these ranges the sections 7,8 and connecting member also have a certain cutting function which makes it easier to get the sample chamber 3 filled with slag.

Side openings 19 are provided in the outer tube 2 at a level below or directly below sand body 5 (when in use). These side openings 19 are positioned either between the sections 7,8 of the cooling element 6 or in line with a section 7,8. The openings 19 avoid that a gaseous medium could get entrapped in the sample chamber 3 therewith preventing the fill of sample chamber 3. The openings also serve to further fill the sample chamber 3 from the top.

Claims

Device for taking slag samples from a container with a molten metal and slag, the device having a sample chamber for receiving a slag sample with an inlet opening and a slag cooling element, characterised in that the slag cooling element extends from the inlet opening into the sample chamber.

Device according to claim 1 , wherein the cooling element extends from the inlet opening over at least half the length of the sample chamber.

Device according to claim 1 or 2, wherein the cooling element comprises two or more sections.

Device according to claim 2 or 3, wherein at least part of a section extends across the inlet opening and/or the sample chamber.

Device according to one or more of claims 2-4, wherein the cooling element comprises two intersecting sections.

Device according to one or more of claims 2-5, wherein at least one section of the cooling element has a stepped part.

Device according to one or more of claims 2-6, wherein the cooling element is provided with a further plate parallel to the plane of the inlet opening of the sample chamber.

Device according to one or more of claims 2-7, wherein a connecting member is provided to connect sections of the cooling element with each other.

Device according to claim 8, wherein the connecting member is positioned in the inlet opening.

10. Device according to one or more of claims 1-9, wherein the sample chamber has a cylindrical shape with opposite of each other a close end and an open end and wherein the open end is the inlet opening.

11. Device according to claim 10, wherein the sample chamber is provided with at least one further opening in the wall of the sample chamber between the inlet opening and the closed end of the chamber.

12. Device according to one or more of claims 1-11 , wherein the sample chamber is build up from a paper tube, wherein the open end of the paper tube is the inlet opening of the sample chamber and a heat resistant body provided in the paper tube makes up the closed end of the sample chamber.

13. Device according to claim 12, wherein the cooling element and the heat resistant body are connected to each other.

14. Device according to claim 13, wherein a further paper tube is provided which fits into the paper tube making up the wall of the sample chamber and wherein the heat resistant body is clamped in the further tube or clamped between the cooling element and the further tube and wherein the cooling element is attached to the further tube.