[TheForge] Blast furnace (Was: microwave heavy metal session)

Fri Feb 13 06:39:01 2004

Mike,

One of the interesting things about most of the new electric arc furnaces is
that they now use an oxygen lance too.  In the best electric arc melting
today about 1/3 of the energy is supplied by the addition of carbon to the
melt and the use of an oxygen lance to "burn" that carbon.  It is also used
as part of the refining process within the electric arc furnace.

World wide about 60 % of the steel is produce in a BOF (basic oxygen
furnace) type unit with most of the rest being electric arc.  In the USA the
electric arc percentage is higher.

Dave Smucker
----- Original Message ----- 
From: "Mike" <[email protected]>
To: <[email protected]>
Sent: Friday, February 13, 2004 1:37 AM
Subject: [TheForge] Blast furnace (Was: microwave heavy metal session)

>
>
> >  One question though: doesn't a blast furnace need the air
> >  blast to oxidize away some of the impurities, or is the
> >  blast solely for obtaining temperature?
>
> As I understand it, in the blast furnace, the air feeds the burning
> coke.  The carbon in the hot coke and the hot CO reduce the iron oxide
> to iron and pass off as CO2.
>
> In an open hearth furnace, an oxygen lance is/can be used to inject
> oxygen that gradually burns off carbon to reduce the carbon content.
>
> An interesting point about an oxygen lance: Stick a pipe into molten
> steel and pump oxy through it to burn any available carbon and
> fizzzzzzzz: the lance burns away.  So they make the lance a pipe
> within a pipe.  Oxy goes through the inner pipe and propane through
> the outer one.  The propane responds to hitting the hot melt with
> catalytic cracking, which is an endothermic process.  So that reaction
> takes up heat from the nearest thing: the lance tip.  Keeps it from
> burning off (at least for a while longer).  The resulting methane or
> ethane (?) then burns but by that time it's further away from the
> lance tip and doesn't do any harm, maybe even helps to keep the melt
> hot.
>
> I don't know how widespread this trick is.  Or was, considering the
> shift to electric arc mini-mills.  But I saw a rig that used it in
> Sydney, NS in the 70s.
>
> - Mike
>
> -- 
> Michael Spencer                  Nova Scotia, Canada       .~.
>                                                            /V\
> [email protected]                                     /( )\
> http://home.tallships.ca/mspencer/                        ^^-^^
>
> -- 
>
>
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