Gatwood, Elden J SAD <Elden.J.Gatwood@...>
Pellets were created to allow more efficient charge in the furnaces. By
binding the limestone or dolomite powder (flux stone) to the refined ore,
with the bentonite, you had product that allowed faster reaction to the heat,
and more consistent distribution within the burden. The pulverized flux
stone also reacted more quickly, instead of taking the time to break down
from crushed stone. The ore would then melt quicker, and impurities would
bind more quickly to the reacting calcium carbonate, forming slag, which
would then float on top of the hot metal. Instead of the slower process of
each layer taking time to react to the ones above and below it, you got
uniform behavior throughout much of the burden. The burden was placed in
layers, then, like CCOOCCO, from bottom to top, instead of CCOOFCCOOFC,
making management of the burden easier. I think that they often used pellets
and refined ore (and even some scrap), in different mixes, before they
figured out how to do the whole thing more effectively. The more you study
blast furnace operations, the more complex it turns out to be.
The pellets I still have are purplish to dirty orange, and would make a very
interesting load to model. Most of the ones I saw were the size of a small
marble or so.
I used to regularly get peppered with pellets watching trains on the PRR,
B&O, Union, and P&LE, since they found every opportunity to escape their
bounds, and escape back to the environment....viva libertad!
From: STMFC@... [mailto:STMFC@...] On Behalf Of eric
Sent: Tuesday, April 08, 2008 3:38 PM
Subject: [STMFC] Re: B&LE triple offset hoppers
Regarding taconite pellets.
After going to the process of extracting the magnetite iron from the
taconite rock, that then mixing it with the bentonite and limestone
to make pellets seems to be counterproductive. After refining the
iron, making pellets is, in effect, diluting it.
So why was it done? Is the hematite the oxidation process creates
considered more valuable than the magnetite?
Wouldn't shipping the pure extracted magnetite be more cost efficient
than diluting it by 35%?