US20180304348A1

US20180304348A1 - A flux feeding apparatus and flux optimization selection method

Info

Publication number: US20180304348A1
Application number: US15/763,589
Authority: US
Inventors: Michael Zinni
Original assignee: Imerys SA
Current assignee: Imertech SAS
Priority date: 2015-09-28
Filing date: 2016-09-28
Publication date: 2018-10-25
Also published as: WO2017055377A1; RU2018112155A; BR112018005709A2; GB201517130D0; BR112018005709B1; RU2729273C2; RU2018112155A3; CN108025353A; EP3356066A1; US20240139801A1

Abstract

A flux feeding apparatus 10 for delivering flux to a mold 13 during a continuous casting process is described. The apparatus comprises: a plurality of silos 20a-20c each containing a different flux or flux component; a receiver 52 for receiving process parameters of the casting process; and a controller 44 which is configured to: analyse the process parameters received by the receiver 52; determine whether a current flux composition is appropriate for the received process parameters; and if the current flux composition is not appropriate for the received process parameters, change the delivery of flux or flux components from the plurality of silos to provide a required flux composition to the mold 13 for the received parameters. A corresponding method is also described.

Description

TECHNICAL FIELD

The present disclosure relates to a flux feeding apparatus and method for delivering flux to a mold during a continuous casting process.

BACKGROUND OF THE INVENTION

It is customary to apply a mold flux, which may be a powder or granular material, onto the top of a slab during continuous casting of a molten metal, such as steel. The flux turns into slag when sufficiently heated by the molten metal. Fluxes are engineered synthetic slags formed by compounds containing oxides, minerals and carbonaceous materials which are selected to provide desired characteristics. For example, the flux may include silica, bauxite, calcium silicate/wollastonite, feldspar, soda ash, fluorospar, lithium carbonate, etc.
At the zone of contact with the liquid metal, the flux serves to prevent reoxidation and avoid heat loss so as to prevent premature solidification of the liquid metal. The flux also absorbs non-metallic inclusions at the liquid slag-metal interface, thereby producing cleaner metal. Further, at the zone of contact with the solidified metal, the flux provides lubrication between the solidified metal shell and the mold. The flux also plays an important role in controlling heat transfer, particularly in a horizontal direction. These functions have a direct impact on the quality and operational stability of the cast steel. For example, inadequate lubrication of the flux can cause loss of containment of the liquid steel due to high friction and shell tearing. Insufficient heat removal will result in thin shell that cannot withstand the ferrostatic pressure and lose steel containment. Excessive heat removal can cause cracks to form on the steel surface, etc.
Flux feeding apparatuses are known which deliver flux automatically or semi-automatically to the mold. For example, in US 2013/0081777, load cell weight sensors are used to control the rate of addition of flux to the mold.
The present invention seeks to provide an improved flux feeding apparatus and method.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a flux feeding apparatus for delivering flux to a mold during a continuous casting process, the apparatus comprising: a plurality of silos each containing a different flux or flux component; a receiver for receiving process parameters of the casting process; and a controller which is configured to: analyse the process parameters received by the receiver; determine whether a current flux composition is appropriate (e.g. optimized) for the received process parameters; and if the current flux composition is not appropriate for the received process parameters, change the delivery of flux or flux components from the plurality of silos to provide a required flux composition to the mold for the received process parameters.
According to another aspect, the process parameters may include user-input parameters and sensed parameters.
According to another aspect, the process parameters may include one or more of: the grade of metal being cast, casting rate/speed, flux consumption rate, heat transfer rate, slag temperature, metal temperature, slag thickness, width, section size, taper.
In another aspect, the controller may select one or more of the plurality of the silos so as to form a mixture of the individual fluxes or flux components.
In yet another aspect, the controller may select one of the silos so as to deliver the flux contained therein to the mold.
In another aspect, the flux feeding apparatus may further comprise a feed head which is connected or connectable to the plurality of silos, wherein the controller is configured to supply the feed head with flux or flux components from one or more of the plurality of silos so as to deliver the required flux composition to the mold.
In another aspect, the feed head may be connected to the silos via a manifold and one or more valves which selectively couple the silos to the feed head.
In another aspect, the one or more valves may be metering valves.
In another aspect, one or more mixing devices may be provided to mix the flux or flux components prior to or in the feed head.
In yet another aspect, the flux feeding apparatus may further comprise an intermediate hopper and a transfer apparatus for transferring mold flux from the silos to the intermediate hopper, wherein the feed head is connected to a feed hopper which is configured to receive flux from the intermediate hopper.
In another aspect, the transfer apparatus may include a vacuum for transferring flux from the silos to the intermediate hopper, and wherein the controller is further configured to control the operation of the vacuum.
In another aspect the transfer apparatus may further comprise a valve which is operable between a first closed position which prevents mold flux from transferring to the intermediate hopper when the vacuum is on, and a second open position which allows mold flux to transfer to the intermediate hopper when the vacuum is off.
In another aspect, the valve may be a flapper valve having a counter weight.
In another aspect, the flux feeding apparatus may further comprise a venturi pump to supply the flux to the feed head.
In another aspect, if the current flux composition is not appropriate for the received process parameters, the controller may generate an alert for an operator.
In another aspect, in response to the alert, the operator may instruct the controller to change the delivery of flux or flux components from the plurality of silos to provide a required flux composition to the mold for the received process parameters.
In another aspect, the flux feeding apparatus may further comprise one or more sensors for determining the process parameters, the one or more sensors being connected to the receiver.
According to another aspect of the invention, there is provided a method for delivering flux to a mold during a continuous casting process, the method comprising: receiving process parameters of the casting process at a controller; analysing the process parameters using the controller; determining whether a current flux composition delivered to the mold from a plurality of silos each containing a different flux or flux component is appropriate for the received process parameters; and if the current flux composition is not appropriate for the received process parameters, changing the delivery of flux or flux components from the plurality of silos so as to provide a required flux composition to the mold for the received process parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

FIG. 1 is a front view of a flux feeding apparatus;

FIG. 2 is a rear perspective view of the apparatus of FIG. 1; and

FIG. 3 is a schematic view of a silo section of the flux feeding apparatus.

DETAILED DESCRIPTION

It is to be understood that at least some of the figures and descriptions of the invention have been simplified to illustrate elements that are relevant for a clear understanding of the invention, while eliminating, for purposes of clarity, other elements that those of ordinary skill in the art will appreciate may also comprise a portion of the invention. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the invention, a description of such elements is not provided herein.
FIG. 1 illustrates an exemplary flux feeding apparatus 10 for delivering flux to a mold 13 during a continuous casting process.
In one embodiment the flux feeding apparatus 10 can include four major components: a transfer apparatus 12; an intermediate hopper 14, a control apparatus 16, and a delivery apparatus 18. The transfer apparatus 12 transfers flux in powder or granular form from a silo 20 to the intermediate hopper 14. The silo 20 may include, for example, one or more large bags or barrels or other containment structures suitable for containing flux or flux components. The delivery apparatus 18 feeds flux 11 from the intermediate hopper 14 onto molten metal 15, such as steel, within the mold 13.
In one embodiment, the transfer apparatus 12 can include a vacuum hopper (or vacuum receiver) 22 having an inlet port 24 to which one end 26 of each of a plurality of flexible suction tubes 28 are connected. The other ends 30 of each of the plurality of flexible suction tube 28 extend into the plurality of silos 20 such that each silo is accessed by at least one flexible suction tube.
In one embodiment vacuum hopper 22 also includes an outlet at the bottom for transferring mold flux to the intermediate hopper 14. On the bottom of the vacuum hopper 22, there can be a valve such as a flapper valve 43 with a counter weight attached. While the vacuum of the vacuum hopper 22 is energized this creates a seal between the flapper valve 43 and the bottom of the vacuum hopper 22. When the vacuum stops, the weight of the material that was picked up allows the flapper valve 43 to open and the material drops into the intermediate hopper 14. The intermediate hopper 14 has a fitting on the bottom that extends into the top of a feed hopper 31 of the delivery apparatus 18. The feed hopper 31 includes a pair of outlet ports 32, 34 (although one or more outlets may be provided) which are each connected to a delivery tube 36, 40. The free ends of the delivery tubes 36, 40 terminate in feed heads 46 which deliver the flux to the mold 13 (or a plurality of molds). The feed heads 46 may form or comprise a distributor to spread the mold flux on the mold surface. The mold flux is pneumatically fed from the feed hopper 31 with venturi pumps 41 which are operatively connected to the outlet ports 32, 34. The number of ports or venturi pumps may vary depending on the type of continuous casting machine or shapes cast.
In one embodiment, the control apparatus 16 further includes a one or more load cells 42 which support the intermediate hopper 14. The load cells 42 can be used to determine the weight of the intermediate hopper 14 and the mold flux contained therein. In one embodiment the intermediate hopper 14 can be isolated from the feed hopper 31 to avoid the feed hopper 31 contributing to the measured weight. The weight of the intermediate hopper 14 can be monitored over a period of time so as to allow the consumption of flux to be monitored in real time.
As shown in FIG. 2, in one embodiment, the control apparatus 16 further includes a controller 44, such as a programmable logic controller (PLC—which may be part of a SCADA (i.e., supervisory, control and data acquisiton) system) or any other suitable computer processor. The controller 44 receives inputs from the load cells 42 and/or other process parameters relating to the metal casting process conditions, and controls the operation of the vacuum 22 in response. Specifically, the controller 44 causes the vacuum 22 to turn on, thus causing mold flux to feed into the intermediate hopper 14, based on a predetermined weight of the feed hopper 31 as compared to the consumption or loss of weight of mold flux calculated using the output of the load cells 42.
In one embodiment, the mold flux composition and rate at which the mold flux is delivered into the mold can be adjusted by the operator using an operator control screen 48 on the controller 44 that can be used for adjusting the feed rate. Alternatively, the mold flux composition and rate at which the mold flux is delivered into the mold 13 can be adjusted by the operator by a wireless handset 50 in communication with a receiver 52 on controller 44. The wireless handset 50 can be used to control the feed rate instead of the operator control screen 48.
Although only one silo 20 is shown in FIG. 1, a plurality of silos 20 a, 20 b, 20 c can be provided, as shown in FIG. 3. Although FIG. 3 shows three separate silos, it will be appreciated that any number of silos may be provided. The silos may also be implemented as separate chambers in a single unit.
In one embodiment, each of the silos 20 a-c contain a different flux or flux component having a different composition. The silos 20 a-c are each connected to the suction tube 28 at a manifold via a valve 54 a-c. The valves 54 a-c are actuated via the controller 44 (or a separate, standalone controller). Accordingly, the valves 54 a-c can be controlled so as to selectively connect a chosen silo 20 a-c to the suction tube 28.
In one embodiment, the receiver 52 (or a separate, standalone receiver which may be wired or wireless) of the controller 44 receives parameters regarding the casting process. In particular, the receiver 52 may receive real time measurements from sensors and/or operator entered characteristics for the casting process. For example, the receiver may receive data including one or more of: the grade of metal being cast (e.g. the grade of steel), casting rate/speed, flux consumption rate (which can be measured using the load cells 42 as described above), heat transfer rate (determined by measuring a temperature increase of cooling water used to cool the mold 13), and the temperature of the slag on top of the mold 13. In particular, Infrared (IR) sensors may be used to measure the surface temperature. Alternatively, thermocouples or other temperature sensors may be used. A laser distance measurement device may also be used to determine the thickness of the layer of flux of the molten metal. The parameters may also include the metal temperature, thickness, width, section size, taper, etc.
In one embodiment, in response to the received parameters, the controller 44 determines the desired composition for the flux and selects the required silo 20 a-c by opening the valve 54 associated with the selected silo 20 and closing the other valves 54. Alternatively, the controller 44 may supply flux which is a mixture of the fluxes or flux components from a plurality of the silos 20 a-c. The valves 54 a-c may allow the relative proportions of each flux to be controlled to provide the desired flux composition. For example, the valves 54 a-c may be metering valves which can accurately control the flow of flux. It will be appreciated that the silos 20 a-c could instead contain constituent elements of mold flux (as opposed to flux itself) which can be combined to provide the desired composition.
In one embodiment, the controller 44 may identify the required flux composition using fuzzy logic, artificial neural networks or other artificial intelligence functions. The controller 44 may determine the correct flux based on the real time process parameters. The flux composition may be adjusted during the casting process or may be fixed for a specific casting run. The controller 44 may determine the flux composition and select the required silo(s) automatically using an algorithm. The controller 44 may determine whether a current flux composition is appropriate (e.g. optimized) for the current process parameters and, if required, make adjustments to the flux or flux components delivered to the mold so as to provide the required flux composition. The controller 44 need not carry out such adjustments autonomously and may instead generate an alert (e.g. an audible or visible alarm) which signals to an operator that a change in flux composition is desirable. If appropriate, the operator may instruct the controller to make such a change. The precise details regarding the corrective action required may be generated automatically by the controller 44 (such that the operator need only approve the change) or may be provided by the operator.
Although the silos 20 a-c have been described as being connected to the suction tubes 28 via valves 54 a-c, it will be appreciated that other arrangements may be used. In particular, the silos 20 a-c may be connected to the tubes 28 using a single valve. Alternatively, each silo 20 a-c may have a dedicated suction tube 28 such that no manifold is required. In fact, the tubes 28 may deliver the flux or flux component from its respective silo 20 a-c directly to the mold 13 such that there is no requirement for the flux or flux components to be mixed. As a further alternative, a robotic arm or the like may transfer the suction tube 28 between silos 20 a-c in response to instructions from the controller 44.
It will be appreciated that the automatic selection of flux composition may be implemented using alternative flux feeding apparatuses than that described above. In particular, the flux feeding apparatus need not have an intermediate hopper 14 nor load cells 42. The flux may also be delivered to the feed heads 46 using alternative means to the vacuum-based system described.
In one embodiment, a method for delivering flux to a mold during a continuous casting process is provided. In one embodiment, the method includes: receiving process parameters of the casting process at a controller; analysing the process parameters using the controller; determining a required flux composition for the received process parameters; and connecting a feed head to one or more of a plurality of silos each containing a different flux or flux component so as to deliver flux of the required composition to the mold.
In another embodiment, the process parameter received by the flux feeder consists solely of the grade of metal to be cast. For example, the grade of steel being cast in a continuous casting apparatus. As the steel grade is changed (as an example), the plant control system and instruct the flux feeder system change the mold flux. The proper silo would open automatically and the other silos would be closed, allowing the system to vacuum the desired flux from the silo and apply it through the distributor. In another embodiment, the flux feeder system can operate to run out the flux in the system before the next flux is selected.
In another embodiment, flux feeder can receive internal signals from the feeder and from the metal casting process system. For example, the flux feeder can receive internal signals relating to the flux feed rate and process parameters, such as for example, heat removal rate from the caster, which when combined are good indicators of flux performance and can be adjusted in real time by mixing fluxes to establish and maintain an optimal balance. This embodiment would also involve metering out of the silos with inline mixing of the fluxes.
The invention is not limited to the embodiments described herein, and may be modified or adapted without departing from the scope of the present invention.
For the avoidance of doubt, the present invention includes the subject matter as defined in the following numbered paragraphs (abbreviated “Para”):
Para 1. A flux feeding apparatus for delivering flux to a mold during a continuous casting process, the apparatus comprising:
a feed head selectably connectable to a plurality of silos each containing a different flux or flux component;
a receiver for receiving process parameters of the casting process; and
a controller which is configured to:
analyse the process parameters received by the receiver;
determine a required flux composition for the received process parameters; and
connect the feed head to one or more of the plurality of silos so as to deliver flux of the required composition to the mold.
Para 2. A flux feeding apparatus as described in Para 1, wherein the process parameters include user-input parameters and sensed parameters.
Para 3. A flux feeding apparatus as described in Para 1 or 2, wherein the process parameters include one or more of: the metal being cast, casting rate/speed, flux consumption rate, heat transfer rate, and slag temperature.
Para 4. A flux feeding apparatus as described in any preceding Para, wherein the controller connects the feed head to a plurality of the silos so as to form a mixture of the individual fluxes or flux components.
Para 5. A flux feeding apparatus as described in any preceding Para, wherein the controller connects the feed head to one of the silos so as to deliver the flux contained therein to the mold.
Para 6. A flux feeding apparatus as described in any preceding Para, wherein the feed head is connected to the silos via a manifold and one or more valves which selectively couple the silos to the feed head.
Para 7. A flux feeding apparatus as described in Para 6, wherein the one or more valves are metering valves.
Para 8. A flux feeding apparatus as described in any preceding Para, further comprising one or more sensors for determining the process parameters, the one or more sensors being connected to the receiver.
Para 9. A flux feeding apparatus as described in any preceding Para, further comprising an intermediate hopper and a transfer apparatus for transferring mold flux from the silos to the intermediate hopper, wherein the feed head is connected to a feed hopper which is configured to receive flux from the intermediate hopper.
Para 10. A flux feeding apparatus as described in Para 9, wherein the transfer apparatus includes a vacuum for transferring flux from the silos to the intermediate hopper, and wherein the controller is further configured to control the operation of the vacuum.
Para 11. A flux feeding apparatus as described in Para 9 or 10, wherein the transfer apparatus further comprises a valve which is operable between a first closed position which prevents mold flux from transferring to the intermediate hopper when the vacuum is on, and a second open position which allows mold flux to transfer to the intermediate hopper when the vacuum is off.
Para 12. A flux feeding apparatus as described in Para 11, wherein the valve is a flapper valve having a counter weight.
Para 13. A flux feeding apparatus as described in any preceding Para, further comprising a venturi pump to supply the flux to the feed head.
Para 14. A continuous casting apparatus comprising a flux feeding apparatus as described in any preceding Para.
Para 15. A method for delivering flux to a mold during a continuous casting process, the method comprising:
receiving process parameters of the casting process at a controller;
analysing the process parameters using the controller;
determining a required flux composition for the received process parameters; and
connecting a feed head to one or more of a plurality of silos each containing a different flux or flux component so as to deliver flux of the required composition to the mold.

Claims

1. A flux feeding apparatus for delivering flux to a mold during a continuous casting process, the apparatus comprising:

a plurality of silos each containing a different flux or flux component;

a receiver for receiving process parameters of the casting process; and

a controller which is configured to:

analyse the process parameters received by the receiver;

determine whether a current flux composition is appropriate for the received process parameters; and

if the current flux composition is not appropriate for the received process parameters, change the delivery of flux or flux components from the plurality of silos to provide a required flux composition to the mold for the received process parameters.

2. A flux feeding apparatus as claimed in claim 1, wherein the process parameters include user-input parameters and sensed parameters.

3. A flux feeding apparatus as claimed in claim 1, wherein the process parameters include one or more of: the grade of metal being cast, casting rate/speed, flux consumption rate, heat transfer rate, slag temperature, metal temperature, thickness, width, section size, taper.

4. A flux feeding apparatus as claimed in claim 1, wherein the controller selects a plurality of the silos so as to form a mixture of the individual fluxes or flux components.

5. A flux feeding apparatus as claimed in claim 1, wherein the controller selects one of the silos so as to deliver the flux contained therein to the mold.

6. A flux feeding apparatus as claimed in claim 1, further comprising a feed head which is connected or connectable to the plurality of silos, wherein the controller is configured to supply the feed head with flux or flux components from one or more of the plurality of silos so as to deliver the required flux composition to the mold.

7. A flux feeding apparatus as claimed in claim 6, wherein the feed head is connected to the silos via a manifold and one or more valves which selectively couple the silos to the feed head.

8. A flux feeding apparatus as claimed in claim 7, wherein the one or more valves are metering valves.

9. A flux feeding apparatus as claimed in claim 6, wherein one or more mixing devices are provided to mix the flux or flux components prior to or in the feed head.

10. A flux feeding apparatus as claimed in claim 6, further comprising an intermediate hopper and a transfer apparatus for transferring mold flux from the silos to the intermediate hopper, wherein the feed head is connected to a feed hopper which is configured to receive flux from the intermediate hopper.

11. A flux feeding apparatus as claimed in claim 10, wherein the transfer apparatus includes a vacuum for transferring flux from the silos to the intermediate hopper, and wherein the controller is further configured to control the operation of the vacuum.

12. A flux feeding apparatus as claimed in claim 11, wherein the transfer apparatus further comprises a valve which is operable between a first closed position which prevents mold flux from transferring to the intermediate hopper when the vacuum is on, and a second open position which allows mold flux to transfer to the intermediate hopper when the vacuum is off.

13. A flux feeding apparatus as claimed in claim 12, wherein the valve is a flapper valve having a counter weight.

14. A flux feeding apparatus as claimed in claim 1, further comprising a venturi pump to supply the flux to the feed head.

15. A flux feeding apparatus as claimed in claim 1, wherein, if the current flux composition is not appropriate for the received process parameters, the controller generates an alert for an operator.

16. A flux feeding apparatus as claimed in claim 15, wherein in response to the alert, the operator instructs the controller to change the delivery of flux or flux components from the plurality of silos to provide a required flux composition to the mold for the received process parameters.

17. A flux feeding apparatus as claimed in claim 1, further comprising one or more sensors for determining the process parameters, the one or more sensors being connected to the receiver.

18. A continuous casting apparatus comprising a flux feeding apparatus as claimed in claim 1.

19. A method for delivering flux to a mold during a continuous casting process, the method comprising:

receiving process parameters of the casting process at a controller;

analysing the process parameters using the controller;

determining whether a current flux composition delivered to the mold from a plurality of silos each containing a different flux or flux component is appropriate for the received process parameters; and

if the current flux composition is not appropriate for the received process parameters, changing the delivery of flux or flux components from the plurality of silos so as to provide a required flux composition to the mold for the received process parameters.