NICKEL MAGNESIUM WIRE INJECTION SYSTEM AND METHOD THEREOF

Abstract

A method of treating liquid iron in a pour furnace includes providing the pour furnace with a body, an inlet for receiving liquid iron, an outlet for dispensing liquid iron, and an access opening located in the body and remote from the outlet. The method also includes suspending a platform over the pour furnace and in alignment with the access opening, injecting a cored wire containing nickel magnesium through the access opening into an interior of the body of the furnace, and reacting the nickel magnesium with the liquid iron in the body of the furnace. The method further includes treating the liquid iron with the magnesium to increase its ductility and strength.

Description

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/017,742, filed Apr. 30, 2020, the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to a system and method of treating ductile iron, and in particular to a system and method of treating ductile iron with a nickel magnesium wire injection.

BACKGROUND

Cast iron is generally not simply a metal, but rather is a composite material of graphite and iron. Graphite is an important material that is naturally formed with sharp edges or corners which reduces the overall strength and ductility of iron, i.e., the iron typically breaks before it bends. To improve the ductility of iron, the iron is alloyed with another material including magnesium. The magnesium is able to reduce the sharp edges or corners caused by graphite, and thereby increase the overall strength and ductility of the cast iron. Due to the properties of magnesium, however, it is difficult to introduce the magnesium to the iron particularly in a pressure pour furnace where the iron is in a liquid form.

Thus, there is a need for a system and process for introducing magnesium into a pressure pour furnace where liquid iron is contained in order to improve the strength and ductility of cast iron.

SUMMARY

In one embodiment of the present disclosure, a method is provided for treating liquid iron in a pour furnace. The method includes providing the pour furnace with a body, an inlet for receiving liquid iron, an outlet for dispensing liquid iron, and an access opening located in the body and remote from the outlet; suspending a platform over the pour furnace and in alignment with the access opening; injecting a cored wire containing nickel magnesium through the access opening into an interior of the body of the furnace; thereby allowing the nickel magnesium to react the liquid iron in the body of the furnace; and increasing the ductility and strength of the liquid iron.

In one example of the present embodiment, the reacting step comprises reacting the liquid iron with the nickel magnesium at a bottom portion of the body of the furnace. In a second example, the injecting step comprises injecting the cored wire by an injector drive motor located on the platform. In a third example, the method may include pressurizing the interior of the body with an inert gas such as nitrogen. In a fourth example, the method may include supplying the cored wire on a spool located on the platform.

In a fifth example, the method may include providing an elongated sheet of steel; placing a powder of the nickel magnesium on the elongated sheet of steel; folding the sheet of steel to form the cored wire of nickel magnesium; rolling the cored wire on a spool; and positioning the spool of the cored wire on the platform. In a sixth example, the injecting step comprises feeding the cored wire into the body of the furnace at a feed rate such that the cored wire reaches a bottom portion of the body before the reacting step. In a seventh example, the reacting step occurs before the cored wire contacts a bottom wall of the furnace.

In another embodiment of the present disclosure, a method of producing ductile iron includes melting scrap metal in a melt furnace to produce liquid iron; forming ductile liquid iron with an alloy; adding the ductile liquid iron to a pour furnace having a body, an inlet for receiving the ductile liquid iron, an outlet for dispensing the ductile liquid iron, and an access opening located in the body and remote from the outlet; checking a quality of the ductile liquid iron by comparing a magnesium content of the ductile liquid iron to a threshold; rejecting the ductile liquid iron if the magnesium content does not satisfy the threshold; positioning a portable injection system above the pour furnace and in alignment with the access opening; injecting a cored wire containing nickel magnesium through the access opening into an interior of the body of the furnace; reacting the nickel magnesium with the liquid iron in the body of the furnace; and increasing the magnesium content in the ductile liquid iron.

In one example of this embodiment, the method may include rechecking the quality of the ductile liquid iron after the reacting step by comparing the magnesium content to the threshold. In a second example, the method may include pouring the ductile liquid iron from the outlet into a cast mold after the rechecking step if the magnesium content satisfies the threshold. In a third example, the method may include pressurizing the interior of the body with an inert gas such as nitrogen. In a fourth example of this embodiment, the method may include forcing the ductile liquid iron from a bottom portion of the furnace to flow towards the outlet when the interior is pressurized with nitrogen.

In another example of this embodiment, the reacting step may include reacting the liquid iron with the nickel magnesium at a bottom portion of the body of the furnace. In yet another example of this embodiment, the injecting step may include feeding the cored wire into the body of the furnace at a feed rate such that the cored wire reaches a bottom portion of the body before the reacting step. Further, in another example of this embodiment, the reacting step occurs before the cored wire contacts a bottom wall of the furnace.

In a further embodiment of the present disclosure, a system for treating liquid iron to restore its ductility is provided. The system includes a pour furnace comprising a body having a top and a bottom, a pour box, an inlet for receiving liquid iron, an outlet defined in the pour box for dispensing liquid iron, and an access opening defined in the top and located remote from the outlet; a portable injector system comprising an injector drive motor disposed on a platform suspended above the top of the pour furnace and aligned with the access opening; and a spool of cored wire formed by an outer steel sleeve and a powder comprising nickel and magnesium within the sleeve, the spool of cored wire located on the platform; wherein, the injector drive motor receives the cored wire from the spool and injects the cored wire into the body of the pour furnace through the access opening at a feed rate at which the powder reacts with the liquid iron near the bottom but before the cored wire contacts the bottom of the pour furnace.

In one example of this embodiment, the system may include a nitrogen pressure system fluidly coupled to an interior of the body of the pour furnace, the nitrogen pressure system configured to supply pressurized nitrogen into the body. In another example of this embodiment, the system may include a programmable logic controller disposed in communication with the injector drive motor, the controller operably controlling the injector drive motor to inject the cored wire at a feed rate where the powder reacts with the liquid iron near the bottom before the magnesium oxidizes. In a further example, the portable injector system is coupled to the pour furnace.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned aspects of the present disclosure and the manner of obtaining them will become more apparent and the disclosure itself will be better understood by reference to the following description of the embodiments of the disclosure, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic of a wire injection system according to the present disclosure; and

FIG. 2 is a flow diagram of a method of injecting nickel magnesium into liquid iron in a pressure pour furnace of the system of FIG. 1.

Corresponding reference numerals are used to indicate corresponding parts throughout the several views.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments described herein and illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended, such alterations and further modifications in the illustrated devices and methods, and such further applications of the principles of the present disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present disclosure relates.

In conventional methods of producing ductile iron, magnesium or some other material may be added to increase the ductility and strength of the iron. Without alloying the iron with magnesium or other material, the iron is often too weak and easily breaks or fractures. Thus, the addition of magnesium or other material strengthens the ductile iron and increases its ductility. However, the use of magnesium introduces other challenges to conventional systems and processes. Magnesium quickly oxidizes at high temperatures, i.e., it begins to vaporize or evaporate. As this happens, magnesium is less effective as an alloy. Thus, some conventional processes may use another alloy besides magnesium.

Another challenge with conventional processes is that when forming ductile iron, the iron cannot be kept or held in a liquid form for extended periods of time. Thus, if there is an issue with the process or an extended downtime, the iron quality often is not acceptable for use. Without any way to add alloy to the iron, the unacceptable iron often must be poured into the mold and discarded. As a result, there is a need for an improved process whereby additional alloy may be added to the liquid iron to boost its quality to acceptable limits.

To better understand the aforementioned challenges, it is helpful to introduce a simplified version of how cast iron is conventionally formed. Generally, a large iron melter or furnace is used to melt scrap metals such as iron. As the iron is melted, it then goes through a primary alloy treatment station where magnesium or other alloy is added to the liquid iron to make ductile iron. After the alloy is added, the ductile iron is added to a large pouring furnace. A high pressure inert gas such as nitrogen may be added to the furnace to pressurize the interior thereof.

When the ductile iron is added to the pouring furnace, the magnesium (if used as the alloy) is unable to remain in the iron for any length of time before it vaporizes. Moreover, ductile iron in the liquid state loses its quality after a short amount of time, and so the timing of this process is important. The pouring furnace holds a large quantity of the liquid ductile iron due to its size. In the event the line shuts down for a lengthy amount of time (e.g., greater than 15-20 minutes), the iron starts to go bad. In the conventional system, the pour furnace is mostly air tight and it is thus difficult to treat the substantial amount of liquid iron in the pour furnace under these conditions. Without any way to pressure or treat the iron effectively, the iron is eventually scrapped.

The present disclosure is directed to a plurality of embodiments for treating ductile iron in the event of a slowdown in production, and the quality of the iron is not acceptable. In particular, a portable wire injection system may be equipped with a spool of a hollow steel wire containing nickel magnesium material. In one example, the nickel magnesium material may be crushed into a powder form, where it is rolled up in a sheet of steel to form a cored wire of nickel magnesium. The steel sheet in effect forms a protective sleeve for the nickel magnesium powder. The steel may be provided in a long, continuous sheet of metal. Once the powder is added to the middle of the sheet, it is then folded or rolled over to form the cored wire. As a result, the cored wire may be long. For example, the wire may be greater than 1 mile in length. The cored wire may be supplied in a spool for use in treating the liquid iron.

The use of nickel in the powder takes advantage of certain qualities of nickel. In particular, nickel is a dense material that allows the powder to reach the bottom of the pour furnace body where the magnesium reacts with the iron. Further, magnesium can be a violent material that intensely reacts with the iron. Nickel, on the other hand, is less violent and can reduce the intensity of the reaction. As a result, nickel magnesium is much less aggressive to refractory. It has also been found that nickel magnesium can further reduce any generation of slag during the reaction, which is helpful to the overall process.

The portable injection system may be suspended above the pour furnace where the nickel magnesium cored wire may be injected directly into the pour furnace. As described above, the cored wire may be provided in a spool on a suspended platform and fed into a machine similar to a welder. The machine may be an injector drive motor which feeds the nickel magnesium cored wire at a desired feed rate into the liquid iron in the pour furnace body such that the powder reaches the bottom of the iron before the steel sleeve melts, thereby allowing the powder to react with the iron. However, the machine may be programmed to limit the feed rate so that the wire does not bounce off the bottom of the furnace.

The portable nature of this system is such that it may be employed when the line is shutdown and the liquid iron sits before going bad. Rather than scrapping the iron, the portable injection system may be deployed to a position above the pour furnace where the nickel magnesium cored wire is injected into the liquid iron to react and thereby restore the quality of the iron.

Referring to FIG. 1 of the present disclosure, a portable injection system 100 is illustrated. The system 100 may include a large pour furnace 102 having a top 110, a bottom 112, an inlet 104, and an outlet 106. The furnace 102 may include side walls as shown. In one example, the pour furnace 102 may be a pressure pour furnace where a constant inert gas pressurizes the interior thereof. In any event, an access opening 114 is located in the top 110 of the furnace 102, where a cap or valve may be installed to selectively open the access opening 114. When the cap or valve is secured, the access opening 114 may be closed.

Liquid iron may be transported into the pour furnace 102 via the inlet 104. It may fill the interior of the furnace to a certain level 118 therein. Above the level 118 of liquid iron, pressurized nitrogen or other inert gas may be pumped into a pressure area 116 via a pump 122 or other device. As the nitrogen or other inert gas fills the pressure area 116, it tends to force the liquid nitrogen from the furnace body (generally defined between the top 110 and bottom 112) into a pour box area 108 adjacent the outlet 108. The pressurized gas is generally used with pressure pour furnaces. If the furnace is not a pressure pour furnace, then the inert gas may not be used to pressurize the interior thereof.

The outlet 108 may be selectively closed by a control rod 136, as shown in FIG. 1. The outlet 108 is defined in a portion of the furnace 102 referred to as a pour spout. In particular, the outlet 108 is formed in the bottom of the pour spout. The control rod 136 may be a graphite or concrete rod which is raised and lowered in a longitudinal direction 136 via a control rod drive mechanism 124. As the control rod 136 is lifted, it uncovers the outlet 108 and allows ductile iron to exit the pour spout and fill a mold 126. When the mold is filled with ductile iron 148 and the pour is complete, the drive mechanism 124 may lower the control rod 136 to close off or cover the outlet 108.

In the event the furnace is a pressure pour furnace, nitrogen is continuously pumped into the pressure area 116 because the nitrogen tends to escape as its density is lower than oxygen. Other inert gases besides nitrogen may be used.

The system 100 of FIG. 1 may also include a portable injection system for injecting nickel magnesium into the furnace via the access opening 114. To do so, a suspended platform 128 may be positioned above the top 110 of the furnace 102 and in alignment with the access opening 114. The platform 128 may be disposed between a few inches to several feet above the furnace. In at least one embodiment, the platform 128 may be coupled to the furnace 102. In another embodiment, the platform 128 may be coupled to a structure other than the furnace 102. In any event, the platform 128 may be suspended above the top 110 of the furnace to allow for the cored wire to be injected through the access opening 114 and into the ductile iron.

The nickel magnesium material may be supplied via a cored wire spool 130 disposed on the platform 128. The spool 130 of wire 132 may be positioned such that an injector drive motor 134 is able to inject the wire 132 into the furnace body at a desired feed rate. The motor 134 may be programmed such that the wire is fed into the furnace at a rate at which the steel wire does not melt until the material reaches the bottom 112 of the furnace and reacts with the iron, but also not too fast such that the wire bounces off the bottom 112 of the furnace. Thus, the steel sleeve protects the material (e.g., powder) long enough so it does reach the bottom of the furnace and reacts with the iron.

The drive motor 134 may be controlled with a programmable logic controller 150 (PLC). The PLC 150 may be software-controlled where it receives a user or operator input in terms of desired magnesium content in the ductile iron. A feed rate or rate of injection may be predefined by the operator or determined by the PLC 150. For instance, the feed rate or rate of injection may be set such that the cored wire is fed fast enough to the bottom of the furnace where the nickel magnesium material reacts with the iron, but not too fast such that the wire bounces off the bottom.

The PLC 150 may communicate or receive additional inputs from other databases or look up tables for determining the current temperate of the iron in the furnace, the current chemistry of the iron (e.g., its current magnesium content or iron quality), among other things. The PLC may then execute one or more calculations to determine the rate at which to inject the nickel magnesium cored wire into the furnace in order to satisfy the desired magnesium content set by the operator. The feed rate may be held constant, or it may vary if desired. The feed rate may be a function of the size and depth of the furnace.

The cored wire may have a certain thickness based on the size of the furnace including its depth and diameter. A larger furnace may require a thicker diameter wire. A larger diameter cored wire may allow for more nickel magnesium powder to be packed into the steel sleeve, but it can also make the wire stiffer and more prone to breaking.

As described above, liquid iron may be supplied via a first path 144 into the inlet 104 of the pour furnace 102. The liquid iron fills the furnace to a certain level 118 as shown. If the furnace is a pressure pour furnace, pressurized nitrogen or other inert gas is pumped 138 into the pressure area 116 of the furnace 102 to force liquid iron near the bottom 112 of the furnace to move in a direction indicated by arrow 142 into the pour box 108. The control rod drive mechanism 124 may raise or lower the control rod 120 along direction 136 to either open or close the outlet 106. When the outlet is open, liquid iron may flow out of the pour box 108 via the outlet 106 along exit direction 146 and into the mold 126.

When the iron quality is not acceptable, the portable injection system is deployed and the injector drive motor 134 is operably controlled by the PLC 150 to feed nickel magnesium cored wire 132 into the furnace body through access opening 114 along direction 140. The cored wire 132 is fed at a feed rate such that the nickel magnesium material reaches the bottom of the furnace and reacts with the liquid iron. Upon reacting with the iron, the quality of the iron may be increased such that the iron has a desired ductility and strength due to the magnesium.

Now that the system has been described in detail, a method of achieving the same is described with reference to FIG. 2. In FIG. 2, a method 200 of controlling the quality of iron in a pour furnace (e.g., pressure pour furnace) is shown. The method 200 is shown including a plurality of blocks or steps for performing the method. The plurality of blocks or steps may include a first block where scrap metal is melted. The scrap metal may be a collection of metal scraps which are recycled or from second use products. The scrap metal may be placed in a melting furnace which is separate from the pour furnace. The melting furnace may include a tap where liquid iron is removed from the melting furnace.

Once the scrap metal is melted, the liquid iron is transported from the melting furnace to a second block 204 where it is alloyed at an alloy treatment station. The alloy may be magnesium, for example, but it may be other known alloys. In block 204, the liquid iron is made more ductile with the addition of the alloy.

After the ductile iron is formed in block 204, the ductile iron is transported and added to the pour furnace 102 in block 204. The iron is added to the pour furnace 102 through the inlet 104 as described above. Nitrogen may be pumped into the furnace (if the furnace is a pressure pour furnace) to pressurize the iron at the bottom of the furnace 102 to flow into the pour box 108. As the iron is added to the pour furnace 102, the method 200 may advance to block 208 where the iron quality is checked. In block 208, a small sample of liquid iron may be taken from the pour furnace 102 to a chemistry station or laboratory where it the magnesium content in the iron is measured. In this block, if the measured magnesium content is within a desired range or otherwise satisfies a predefined threshold as acceptable, the iron is considered satisfactory to pour into the mold. In this case, the method 200 may advance to block 210 where the ductile liquid iron is released from the pour spout of the furnace 102 by raising the control rod 120 to open the outlet 106. As this happens, iron may flow out of the furnace 102 and into the mold 126. During execution of block 210, the method 200 may further advance to block 212 where a determination is made whether additional iron is required for the pour. If so, more scrap metal may be melted in block 202 and the method 200 may advance in the same manner as described until enough iron is poured into the mold for a desired casting. If there is no need for additional iron to be poured, then the casting is complete. A new mold may be placed below the outlet to be filled with iron as described. This may continue so long as the iron quality is acceptable in block 208.

In the event the iron quality is not acceptable in block 208, this may be due to an extended downtime or other problem in the method 200. In this case, the method 200 may utilize the portable nickel magnesium injection treatment to restore the iron quality in block 214. More specifically, in block 214, the portable injection system may be provided on the suspended platform 128 at least partially overhanging the top 110 of the pour furnace 102. In its appropriate position, the suspended platform is aligned with the access opening 114 of the furnace 102 so allow the nickel magnesium cored wire 132 to be injected through the access opening 114 and into the pour furnace body. The injection system may include the spool 130 of cored wire 132 disposed on the platform 128 along with an injector drive motor 134 operably controlled by the PLC 150. The drive motor 134 may operably inject the cored wire 132 into the furnace 102 such that the nickel magnesium reacts with the liquid iron near the bottom 112 of the furnace. As this happens, the addition of magnesium is able to restore the ductility and strength of the iron, while the nickel is able to reduce the intensity of the reaction and reduce any slag production therein.

Once the nickel magnesium treatment is added to the iron, block 214 is completed and the method advances back to block 208 where the iron quality is rechecked. If the iron quality is acceptable, the iron may be poured in the mold 126 in block 210 as described above. If the iron remains unacceptable in block 208, the method 200 may return to block 214 for an additional nickel magnesium treatment.

While exemplary embodiments incorporating the principles of the present disclosure have been described herein, the present disclosure is not limited to such embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains.

Claims

1. A method of treating liquid iron in a pour furnace, comprising:

providing the pour furnace with a body, an inlet for receiving liquid iron, an outlet for dispensing liquid iron, and an access opening located in the body and remote from the outlet;

suspending a platform over the pour furnace and in alignment with the access opening;

injecting a cored wire containing nickel magnesium through the access opening into an interior of the body of the furnace;

reacting the nickel magnesium with the liquid iron in the body of the furnace; and

treating the liquid iron with magnesium from the nickel magnesium material to increase its ductility and strength.

2. The method of claim 1, wherein the reacting step comprises reacting the liquid iron with the nickel magnesium at a bottom portion of the body of the furnace.

3. The method of claim 1, wherein the injecting step comprises injecting the cored wire by an injector drive motor located on the platform.

4. The method of claim 1, further comprising pressurizing the interior of the body with an inert gas.

5. The method of claim 1, further comprising supplying the cored wire on a spool located on the platform.

6. The method of claim 1, further comprising:

providing an elongated sheet of steel;

placing a powder of the nickel magnesium on the elongated sheet of steel;

folding the sheet of steel to form the cored wire of nickel magnesium;

rolling the cored wire on a spool; and

positioning the spool of the cored wire on the platform.

7. The method of claim 1, wherein the injecting step comprises feeding the cored wire into the body of the furnace at a feed rate such that the cored wire reaches a bottom portion of the body before the reacting step.

8. The method of claim 7, wherein the reacting step occurs before the cored wire contacts a bottom wall of the furnace.

9. A method of producing ductile liquid iron, comprising:

melting scrap metal in a melt furnace to produce liquid iron;

forming ductile liquid iron with an alloy;

adding the ductile liquid iron to a pour furnace having a body, an inlet for receiving the ductile liquid iron, an outlet for dispensing the ductile liquid iron, and an access opening located in the body and remote from the outlet;

checking a quality of the ductile liquid iron by comparing a magnesium content of the ductile liquid iron to a threshold;

rejecting the ductile liquid iron if the magnesium content does not satisfy the threshold;

positioning a portable injection system above the pour furnace and in alignment with the access opening;

injecting a cored wire containing nickel magnesium through the access opening into an interior of the body of the furnace;

reacting the nickel magnesium with the liquid iron in the body of the furnace; and

increasing the magnesium content in the ductile liquid iron.

10. The method of claim 9, further comprising rechecking the quality of the ductile liquid iron after the reacting step by comparing the magnesium content to the threshold.

11. The method of claim 10, further comprising pouring the ductile liquid iron from the outlet into a cast mold after the rechecking step if the magnesium content satisfies the threshold.

12. The method of claim 9, further comprising pressurizing the interior of the body with an inert gas.

13. The method of claim 12, further comprising forcing the ductile liquid iron from a bottom portion of the furnace to flow towards the outlet when the interior is pressurized with the inert gas.

14. The method of claim 9, wherein the reacting step comprises reacting the liquid iron with the nickel magnesium at a bottom portion of the body of the furnace.

15. The method of claim 9, wherein the injecting step comprises feeding the cored wire into the body of the furnace at a feed rate such that the cored wire reaches a bottom portion of the body before the reacting step.

16. The method of claim 15, wherein the reacting step occurs before the cored wire contacts a bottom wall of the furnace.

17. A system for treating liquid iron to restore its ductility, comprising:

a pour furnace comprising a body having a top and a bottom, a pour box, an inlet for receiving liquid iron, an outlet defined in the pour box for dispensing liquid iron, and an access opening defined in the top and located remote from the outlet;

a portable injector system comprising an injector drive motor disposed on a platform suspended above the top of the pour furnace and aligned with the access opening; and

a spool of cored wire formed by an outer steel sleeve and a powder comprising nickel and magnesium within the sleeve, the spool of cored wire located on the platform;

wherein, the injector drive motor receives the cored wire from the spool and injects the cored wire into the body of the pour furnace through the access opening at a feed rate at which the powder reacts with the liquid iron near the bottom but before the cored wire contacts the bottom of the pour furnace.

18. The system of claim 17, further comprising an inert gas pressure system fluidly coupled to an interior of the body of the pour furnace, the inert gas pressure system configured to supply an inert gas into the body.

19. The system of claim 17, further comprising a programmable logic controller disposed in communication with the injector drive motor, the controller operably controlling the injector drive motor to inject the cored wire at a feed rate where the powder reacts with the liquid iron near the bottom before the magnesium oxidizes.

20. The system of claim 17, wherein the portable injector system is coupled to the pour furnace.