Furnace Tap Hole Question

[ZacMech]

Hi all,

Not sure if this is the best area to post this, but here goes. I'm working at a large smelting facility. The tap hole at the slag end of our furnace has the typical method of plugging/opening. That is, a clay gun as well as a drill rod in a single unit. However, while the slag is running, what the operators call a "rose bud" is used to control and direct (downward into the launder) the slag flow. The rosebud is basically a pipe with a copper tip, which also has water running through it to cool it. They control the flow by how far they push it into the tap hole. Has anyone ever seen this type of arrangement? I do not have much experience in this area, but all my research has not turned up anything remotely similar. Thanks in advance for any responses.

 

[kchan711]

Hi ZacMech,

I used to work for Mittal Steel as a Plant Engineer near Chicago. They used a Basic Oxygen Furnace (BOF) that used an overhead Oxygen Lance (with copper tip and water cooling) to remove steel impurities. Their method of controlling slag was to simply keep it away from the tap hole. The ladle would come under the furnace, the tap hole on the side of the BOF was bored out, and then the whole furnace would tip to its side pouring the steel into the ladle. Being that slag is significantly less dense than steel, it remained on top of the mix. Much of the remaining slag would be left for the next steel heat.

I have never seen your tapping method. I'm also not sure if you're in the steel industry. If the Copper Oxygen Lance (in Mittal's case) came in contact with the molten steel, even with water cooling, it would be destroyed. The heat just couldn't be removed fast enough.

Are you trying to better design this system? What kind of smelting facility is this? I'll try to be as much help as possible.

Regards,

Kyle

Kyle Chandler

http://www.KylesGuide.com

"To the Pessimist, the glass is half-empty. To the Optimist, the glass is half-full. To the Engineer, the glass is twice as large as it needs to be!"

 

[Metalmeister]

Dear Mechs:

If the rosebud works, don't mess with it.

Smelting is a term used for the removal of metal from its ore through a chemical reduction process, although the term is also applied to other metal refining operations such as copper, aluminum, nickel, etc operations, even if they are cold metal shops (i.e., charged with scrap metal).

In ladle refining, I believe the copper lance is plunged through the slag into the molten steel. Copper backing plates are also used in welding (no water cooling) and in a continuous cast plate mill (with water cooling). Copper has a very high heat transfer coefficient so that the copper won't melt.

 

[kchan711]

The copper lance does not necessarily come into direct contact with the molten steel. It launches oxygen into the bath at supersonic speeds, which then establishes a thermal fluid barrier. This is turn is also aided by water cooling being pumped through the copper lance head.

Berry Metals in Harmony, PA is one of the largest oxygen lance manufacturers in the U.S. That might be a good place to get information on cooling and slag control.

Kyle Chandler

http://www.KylesGuide.com

"To the Pessimist, the glass is half-empty. To the Optimist, the glass is half-full. To the Engineer, the glass is twice as large as it needs to be!"

 

[deadrange]

To add to kcham711's statement. Having working in a BOP shop, some of the slag is poured off from the furnace prior to tap. A side tap hole is used to prevent slag from carrying over into the ladle during tap. However, since there is a significant potential to vortex in slag if one is not careful there are numerous methods to help stop this from happening.

One such method is a vibrational sensor. Another is visual detection. While to the naked eye it appears bright and the same color, through computer filtering it can show difference to stop the tap stream.

While the transfer of slag into the ladle is bad, retaining some slag in the furnace is a good thing. Many steelmills are not employing the idea of slag splashing, to help lengthen the life of their furnace refractories. Just a few thoughts.

There are also mechanical methods for stopping slag as well.

To metalmesiter: I am not sure i have ever heard of ladle refining using a oxygen lance, since the point of steelmaking is to remove the oxygen that you had to put in to bring the carbon down. Typically reheating during ladle processing is done with an electrode, either AC or DC. More commonly in the US its an AC three electrode set-up. DC is a single electrode, which is what you may be thinking of.

Oxygen lances are really more designed for the furnace itself.