CN1132483A

CN1132483A - Purifying molten metal

Info

Publication number: CN1132483A
Application number: CN 94193666
Authority: CN
Inventors: M·R·克拉克; D·苏顿
Original assignee: Foseco International Ltd
Current assignee: Foseco International Ltd
Priority date: 1993-08-28
Filing date: 1994-07-29
Publication date: 1996-10-02
Also published as: FI960910A0; BR9407587A; AU7234994A; JPH09501871A; FI960910A; EP0714330A1; TW360570B; WO1995006534A1; CA2170530A1

Abstract

The invention relates to a means of purifying molten metal in a vessel, e.g. a tundish wherein an active inclusion-removing covering layer may be used in a more cost-effective manner. Accordingly, the invention provides a method of purifying molten metal in a molten metal handling vessel (10, 10'), the vessel having an inlet region (A, A') and an outlet region (C, C') for the molten metal, characterised in that the vessel (10, 10') is divided to include a cleaning region (B, B') between the inlet region (A, A') and the outlet region (C, C'), the molten metal (21, 21') is caused to flow from the inlet region (A, A') through the cleaning region (B, B') to the outlet region (C, C') and an active inclusion-removing covering layer (23, 23') is placed on the surface (22, 22') of the molten metal (21, 21') in the cleaning region (B, B').

Description

Purifying molten metal

The present invention relates to a kind of method and apparatus that purifies liquid metal, be specially adapted to purify hot metal in the casting process.For simplicity, be that the present invention will be described for example below specially with the purify hot metal.

In the continuous casting steel machine process, molten steel injects continuous cast mold from ladle by intermediate receptacle, and intermediate receptacle is called as tundish, its effect as same holder with constant level.

Usually molten steel is just smelted, and just handles to remove unwanted impurity or inclusion before it enters ladle and/or after entering ladle, just molten steel is injected tundish then.These are handled and generally are generically and collectively referred to as secondary refining process, comprising the blowing inert gas of ladle slag removal, vacuum-treat, stirring of inert gas, flux processing or pulvis.

And, can comprehensively adopt wherein two or more treatment process to obtain high quality molten steel, particularly high molten steel purity.Yet, always some impurity no matter be solid-state or liquid, enter tundish from ladle.Flow into the process of tundish from ladle at molten steel in addition, because of can further generating inclusion, as oxide inclusion with air generation oxygenizement.

Molten steel also is easy to further increase foreign matter content in tundish.Therefore, common at present employing the whole bag of tricks is removed the impurity in the molten steel in tundish, comprising making molten steel pass through various barricades, weir or dividing plate in the flow process in tundish.Barricade, weir and dividing plate can be made by the refractory materials that can absorb inclusion particle.

A kind of method of removing inclusion in the tundish liquid metal was once disclosed in the 5th volume the 43rd phase (M-60) (715) of Japanese Patent digest and JP-A-56-001252.Liquid metal is isolated up and down by one group between being arranged in from the inlet region to the outlet area, the refractory materials shelf of horizontal stretching, the adsorbable inclusion particle of shelf.Another kind of similar method is disclosed in our European patent No. 0376523 (FS1410/1421).Disclosed purification metal process comprises that the molten steel that makes in the tundish is by one group between the outlet area that leaves tundish in the molten steel inlet region from the ladle to the tundish to the molten steel vertical dividing plate of placing, this group dividing plate is across in tundish, leave certain distance between the dividing plate, molten steel is limited in interior the flowing of passage between the dividing plate.If can make molten metal, normally molten steel produces flowing of making progress, and adopts a kind of active flux layer of surface coverage in tundish, and then aforesaid this invention is particularly useful.Such flux layer itself can also be caught them effectively with the inclusion reaction in the molten steel, thereby it is removed from steel stream.

Be appreciated that " inclusion " speech comprises endogenous inclusion and foreign impurity, inclusion can be separated from one another, also can be in groups.Under any circumstance, the molten steel inclusion all is deleterious in the tundish, perhaps attached to the long nozzle bore surface that stretches to crystallizer under the tundish, perhaps enter and cause in the crystallizer that casting billet surface and internal soundness worsen, thereby the strand metallurgy characteristic is produced detrimentally affect.

Except that above-mentioned active flux, people know that quoting a kind of pulvis tectum covers molten steel surface in the tundish, its objective is make between molten steel and the air adiabatic to reduce thermosteresis.

Also recommend to adopt two-layer or multi-functional tundish to cover slag blanket, so that obtain both can be incubated, can remove the overall merit of inclusion again like this.The main component that typical insulation covers slag blanket is magnesium oxide or pure aluminium silicate, and the active flux layer of removing inclusion then contains such as compositions such as aluminum oxide, lime and silicon-dioxide.

People will recognize that the active flux layer is more expensive than simple thermal insulation layer, therefore, need provide a kind of more economical method to remove inclusion from the container such as tundish one class.

And we find that the active surface tectum can cause some problems in the container entrance district, and the existence of turbulent flow and flux can cause undesirable reaction and make the flux in this district form crust.When using the refractory materials stopper when opening and closing the mouth of a river of container, active flux destroys the Chemical Composition of stopper, thereby shortens its acceptable life in addition.

Therefore, purpose of the present invention is a kind of by removing the better method that harmful inclusion makes purifying molten metal with regard to providing, and this method can also overcome the problems referred to above or reduce its influence.

So, the invention provides a kind of method that in the liquid metal processing vessel, purifies liquid metal on the one hand, this container has a liquid metal inlet region and an outlet area.Its characteristics are: constitute a purifying area between inlet region and outlet area, make molten metal flow to outlet area from the inlet region by purifying area, add one deck on the surface of purifying area molten metal and have active inclusion removal tectum.

On the other hand, the invention provides a kind of molten metal processing vessel that comprises molten metal inlet region and outlet area.Its characteristics are: this container has a purifying area between inlet region and outlet area, and has the device of restriction purifying area molten metal surface coverage slag blanket.

The present invention is specially adapted to remove the inclusion by in the molten steel of tundish.As previously mentioned, further specify below in conjunction with specific embodiment.

Tundish is divided into the weir that the device in needed some districts is preferably made with suitable refractory materials, it is refractory plate, this refractory plate is suspended on the top of tundish, liquid steel level is stretched out in its upper end, the lower end is stretched at the bottom of the tundish, and and wraps at the end and leave enough gaps so that molten steel passes through.In given embodiment, tundish is divided into three districts by two such weirs, and two weirs arrange that along the tundish length direction each weir is all across the whole width of tundish.Constitute the central purge district between two weirs, a side of purifying area is the inlet region, and opposite side is an outlet area.

A kind of active middle cinder inclusion is as REACTOL ^TM, can float over the purifying area molten steel surface, middle cinder inclusion is remained in the purifying area by the weir of stretching out the molten steel face.If desired, the inlet region can cover different protective layers with the interior molten steel surface of outlet area, preferably the insulation covering slag of standard.

As required, barricade, the weir of other that can set up also in the tundish that general tundish adopts and have some characteristic that common tundish has.For example, be provided with impact pad usually in bottom, tundish inlet region to bear the molten steel liquid stream that enters tundish and to reduce of the etch of liquid stream to this district's bag end.

In a better implement example, be provided with a upwardly extending refractory materials barricade in purifying area tundish bottom.When molten steel when the bottom on the weir that indicates the purifying area zero position enters purifying area, be subjected to the restriction of this barricade and upwards flow, flow to active tectum.In this embodiment, preferably make the upwardly extending height of barricade surpass at the bottom of the tundish bag and the bottom on the weir that molten steel is flow through when entering purifying area between the gap.

Can adopt rare gas element as required,, form rising bubble by the molten steel in the purifying area as argon gas.Find that this method can promote inclusion floating, make it to contact with active tectum.Rare gas element can be blown in above-mentioned barricade easily.

Barricade can be any shape easily, and as truncated triangles, the conical surface upwards.Under this shape, rare gas element is easy to blow out from the end face of barricade.Yet another kind of ideal method is that one " L " shape barricade is set, and rare gas element blows out from the bottom of " L ", can prevent that like this molten steel katabatic drainage and the steel stream that makes progress along L wall straight flange from directly bump taking place.

In another embodiment, have many eyelets on the barricade, barricade can force a part of molten steel upwards to flow like this, and remaining molten steel then passes eyelet on the barricade.In this embodiment, source of the gas preferably is located at the tundish bottom that is positioned at barricade with holes downstream one side, makes steel flow cross the upstream that just runs into behind the barricade from source of the gas.

As the weir on purifying area border (with any other barricade and weir in the tundish) a rough surface is arranged preferably, have gauffer, knob or rill as the surface.Can increase the surface-area that the weir contacts with molten steel in this way, for example can increase 3 times, in addition more.Can significantly increase the ability that inclusion " is caught " on the surface, weir like this.Embodiment given here surface has knob, and these knobs can be such as round end taper or pyramid, perhaps surface design to be become the rill that extends along its length.

The weir is preferably made by the aluminum oxide refractory materials, so that absorb the Calucium Silicate powder inclusion, this inclusion is a main non-metallic inclusion common in the tundish molten steel.But need not all to adopt the aluminum oxide refractory materials on the whole thickness on weir, find the comparatively cheap anti-material of middle employing on weir, upper layer is proper for the aluminum oxide refractory materials.

Embodiments of the invention only are described below in conjunction with the accompanying drawings.

Fig. 1 is the tundish skiagraph of first embodiment of the invention.

Fig. 2 is a fragmentary, perspective view of cuing open the weir behind the part tundish among Fig. 1.

Fig. 3 is the tundish skiagraph that second embodiment of the invention is similar to Fig. 1.

Fig. 4 cuts open among Fig. 3 the fragmentary, perspective view on weir behind the part tundish.

Among Fig. 1, tundish 10 has a steel shell 11, shell 11 has an integrated poured refractory materials permanent layer liner 12, the internal surface of liner 12, if promptly do not establish refractory materials lining thereon with surface that the tundish molten steel contact on have the inflatable refractory materials of one deck to serve as a contrast 13.

Tundish is divided into three district A, B and C by two refractory materials weirs 14 and 15.Weir 14 and 15 is provided with along the tundish length direction, and is across the whole width of tundish, separated by a distance between two weirs.Weir 14 and 15 all protrudes upward, and is higher than the highest upper edge 10A of tundish, but does not have downwards enough degree of depth to arrive at the bottom of the tundish 16.Tundish " B " district is positioned between

weir

14 and 15, is the tundish purifying area.

The upstream on weir 14 " A " district is the inlet region, and molten steel enters this district by common ladle (not shown) mouth of a river protective sleeve 17. impact pad 18 is located on the tundish bottom 16 of ladle nozzle protective casing 17 belows in order to accept steel stream and to prevent the excessive etch of steel stream to this district's liner.

The downstream on weir 15 is outlet area " C ", comprises outlet 19 and one stopper 20 that is positioned at the bag end 16.The lifting stopper is with the switching of control outlet as required.

Shown in molten steel 21 filled tundish, its liquid level is 22.It on the molten steel face 22 of purifying area " B " the active tundish covering slag 23 of one deck.This layer covering slag can only be remained in the purifying area by

weir

14 and 15 encirclements.Cover one deck standard insulation covering slag on " A " district and " C " district molten steel surface 22.Like this, required active covering slag consumption can reduce relatively, and it is best that the tectum purification efficiency reaches.And active slag blanket 23 and the ladle slag that enters tundish are separated fully.Therefore can realize long sequence casting, the efficient that covers slag blanket until activity obviously reduces.

Weir, upstream 14 stretches at the bottom of the tundish 16, and it highly is the gap of " a " that the lower end on weir and bag leave at the end.Similarly, the bag end 16, are also stretched on weir, downstream 15, and it highly is the gap of " c " that its lower end and bag leave at the end 16.Barricade 25, extends upward from the bag end between

weir

14 and 15 across the whole width of tundish, and the height on it at the bottom of end distance bag is " b ".As shown in the figure, " b " greater than " a " and " c ", and the steel that can force from the weir 14 bottom to flow into " B " district like this flows to steel stream interface 22 and active slag blanket 23 thereof.

The argon gas of being supplied with by suitable source of the gas (not shown) blows out from exporting 26.Argon blowing hole is located at barricade 25 upper edge tundish widths and arranges, and is at regular intervals between each hole.Argon gas bubbles 27 is to molten steel face 22 directions come-ups, promotes in the molten steel inclusion (not shown) come-up and contacts with active tectum 23.

At tundish outlet area c, to establish one and consume barricade 28, this barricade is located at the upstream side of outlet 19, extends upward from the bag end, across whole tundish width.This barricade can be, for example, and slimy refractory plate.After molten steel injected tundish from ladle, under the molten steel effect, this barricade was very fast, for example is no more than 10 minutes, is just disintegrated.Its objective is and block the low temperature molten steel that is introduced into tundish, the higher steel flow of temperature is crossed arrived outlet behind this barricade at first, the danger that molten steel freezes takes place thereby can reduce the exit.

As figure, shown in,

weir

14 and 15 is at a distance of be " X ", wherein " X "=" y "+" z ", " y " be medullary ray from barricade 25 to the weir 14 metope (downstream side) in the distance of wrapping end projection; Similarly, " z " be barricade 25 medullary rays to the weir 15 metope (upstream side) in the distance of bag end projection.The optimum length of " a ", " b ", " c ", " x ", " y " and " z " is different because of tundish certainly, but the personnel with general technology level can determine suitable dimensional parameters very soon to the bag type of any special case, so that molten steel and active slag blanket 23 have best duration of contact, and can guarantee to be enough to satisfy the continuous pouring condition by the molten steel flow at the tundish arrival exit mouth of a river 19.

The knob 29 that a series of truncated cone shapes are arranged on the metope on weir 15 is faced at it at least in weir 14 shown in Figure 2, to improve the ability that it " catches " inclusion.

Shown in Figure 3 is to be similar to tundish 10 ' shown in Figure 1, and the label of each several part is identical with the label of corresponding section among Fig. 1 in the tundish 10 ', just the upper right footmark of label " ' ".

The same with Fig. 1, tundish 10 ' is divided into three district A ', B ' by two refractory materials weirs 14 ' and 15 ' and C ', B ' district is purifying area.As the front, in inlet region A ', be provided with impact pad 18 ', in order to accept steel stream, 16 ' is provided with outlet 19 ' at the bottom of the bag of outlet area C '.

Active tundish covering slag 23 ' covers B ' district molten steel surface, then adopts one deck standard insulation covering slag 24 ' in A ' district and C ' district.

The setting on weir, upstream 14 ' and weir, downstream 15 ' is similar to the relative position relation that Fig. 1 provides as shown in the figure.Be provided with barricade 25 ' with holes between the weir 14 ' and 15 ', this barricade extended upward from the bag end 16 ', across whole tundish width.As the front, the steel stream in inflow B ' district, 14 ' bottom is forced to upwards flow to molten steel face 22 ' and active slag blanket 23 ' from the weir.Different is that some molten steel is by the through hole 25A on the barricade 25 '.

The argon gas of being supplied with by suitable source of the gas (not shown) blows out from air blowing brick 30, and the air blowing brick is near the downstream side of barricade 25 ', at the bottom of the tundish bag.The Argon Bubble (not shown) to molten steel surface 22 ', promotes that inclusion (not shown) come-up is to contact active tectum 23 ' in the molten steel to come-up.

Though (it is not shown to should be understood that figure goes up, and tundish 10 ' will be equipped with the opening and closing device that resembles stopper one class for exporting 19 ' among Fig. 3.)

As shown in Figure 4, weir 14 ' has truncated pyramidal knob 29 ' to improve the inclusion capture ability.Weir 15 ' also has similar knob.

Should be understood that above-mentioned different embodiment to change to some extent and do not depart from scope of the present invention and essence.

As noted earlier, the weir can have and disclosed variform surface; Outlet flow control devices can be revolving valve, sliding water valve or simple metering nozzle; Impact pad can be dome-shaped or other desired shape.

Claims

1. one kind at liquid metal processing vessel (10,10 ') purify the method for liquid metal in, this container (10,10 ') has an inlet region (A, A ') and an outlet area (C, C '), it is characterized in that, container (10,10 ') at inlet region (A, A ') and outlet area (C, C ') forms a purifying area (B between, B '), liquid metal (21,21 ') be forced to from inlet region (A, A ') by purifying area (B, B ') flows to outlet area (C, C '), at purifying area (B, B ') liquid metal (21,21 ') surface (22,22 ') cover one deck active inclusions decoat (23,23 ').

2. the method for claim 1 is characterized in that, container is provided with two weirs (14,14 ' and 15,15 ') and is provided with along its length direction in (10,10 '), across its whole width, form purifying area (B, B ') between Liang Yan.

3. method as claimed in claim 2, it is characterized in that, weir (14,14 ' and 15,15 ') is a refractory plate, the position of the maximum height that metal liquid can reach from be higher than container (10,10 ') is stretched to the container bottom of (10,10 ') (16,16 ') downwards, and and bottom (16,16 ') between keep enough gaps (a, a ' and b, b ') so that enough metal liquids flow through.

4. as claim 2 or 3 described methods, it is characterized in that the active material tectum (23,23 ') of removing inclusion is limited in the zone between two weirs (14,15 and 14 ', 15 ').

5. as above-mentioned any described method of claim, it is characterized in that (A, A ') and outlet area (C, C ') liquid metal (21,21 ') surface (22,22 ') covers one deck standard adiabator layer in the inlet region.

6. as above-mentioned any described method of claim, it is characterized in that from the container bottom of (10,10 ') (16,16 ') a upwardly extending refractory materials barricade (25,25 ') being arranged under the barricade effect so that the liquid metal of inflow purifying area (B, B ') is forced upwards to flow.

7. method as claimed in claim 6 is characterized in that, the rare gas element formation bubble floating that is blown at purifying area (B, B ') passes liquid metal (21,21 ').

8. method as claimed in claim 7 is characterized in that gas blows out from the upper face of barricade (25).

9. method as claimed in claim 7, it is characterized in that barricade (25 ') has through hole (25A), a part of liquid metal is flow through from the hole, in the downstream side of barricade (25 '), gas blows out from the source of the gas (30) that is positioned at container (10 ') bottom (16 ').

10. a liquid metal processing vessel (10,10 '), comprise a liquid metal (21,21 ') inlet region (A, A ') and an outlet area (C, C '), it is characterized in that, between inlet region (A, A ') and outlet area (C, C '), this container (10,10 ') has a purifying area (B, B ') and surrounds the device (14,14 ' and 15,15 ') that this purifying area (B, B ') interior liquid metal surface (22,22 ') covers slag blanket (23,23 ').

11. liquid metal processing vessel as claimed in claim 10, it is characterized in that, device (14,14 ' and 15,15 ') is the pair of refractory material plate, along container length direction setting and across entire container (10,10 ') width in order to define the purifying area (B, B ') between them.

12. liquid metal processing vessel as claimed in claim 11, it is characterized in that plate (14,14 ' and 15,15 ') stretches to the container bottom of (10,10 ') (16,16 ') downwards and also and between the container bottom remains with gap (a, a ' and c, c ') so that liquid metal passes through from being higher than metal liquid (21,21 ') can reach in the container (10,10 ') maximum height.

13., it is characterized in that barricade (25,25 ') extends upward from the container purifying area of (10,10 ') (B, B ') bottom (16,16 ') as claim 10,11 or 12 described liquid metal processing vessels.

14., it is characterized in that rare gas element source of the gas (26,30) is located at the bottom (16,16 ') near container (10,10 ') as any one described liquid metal processing vessel in the claim 10 to 13.

15., it is characterized in that the outlet of source of the gas (26) is located on the barricade (25) as claim 14 described liquid metal processing vessels.

16. liquid metal processing vessel as claimed in claim 15 is characterized in that, barricade is " L " shape, and gas blows out from the bottom in the downstream side " L " of barricade.

17. as claim 13 or 14 described liquid metal processing vessels, it is characterized in that, have through hole (25A) on the barricade (25 ') and allow liquid metal to flow through through hole.

18. liquid metal processing vessel as claimed in claim 17 is characterized in that, source of the gas (30) is located at the bottom (16 ') of the container (10 ') in barricade (25 ') downstream side.

19., it is characterized in that the surface of facing purifying area (B, a B ') side at refractory plate (14,14 ' and 15,15 ') has knob (29,29 ') as any one described liquid metal processing vessel of claim 11 to 18.

20. as any one described liquid metal processing vessel of claim 10 to 19, it is characterized in that, this container is a tundish (10,10 '), has inlet poured apparatus (17), the molten metal of an impact pad (18,18 ') in order to accept to inject, and the outlet (19 ') of an available stopper (20) or slide gate nozzle switching.