TITLE: BLast Furnace
NAME: Dave Merchant
COUNTRY: USA
EMAIL: kosh@nesys.com
WEBPAGE: www.nesys.com
TOPIC: Elements
COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT.
JPGFILE: blast.jpg
RENDERER USED: 
    povray 3.01

TOOLS USED: 
    Photoshop for JPEG conversion

RENDER TIME: 
    6 hour 16 min 5 secs

HARDWARE USED: 
    P300, 40 mb RAM, W95

IMAGE DESCRIPTION: 


Iron was one of the first elements that humans learned to deal with directly.
It is abundant in nature, as iron oxide, and extremely useful in the pure
or alloyed state.

To separate the elemental iron from the oxygen atoms (in one of several
stable compounds) requires high heat, which humans learned to achieve some
6000 years ago. Over the course of thousands of years, iron technology
evolved on an increasing scale to the modern blast furnace, and is now
continuing toward direct conversion of iron ore to steel.

In the meantime, the use of elemental iron was largely supplanted by the
development of steel, which is still primarily iron, with small amounts of
other metallic elements added to lock into the crystal lattice.

In this scene, nearly pure iron is being tapped from a blast furnace into
large, firebrick lined "bottle cars" or "hot metal cars", on its way to
be converted to steel, in a Bessemer converter, open hearth, electric
furnace, or BOF/BOP converter, depending on the era and location.

These insulated cars can keep the iron molten for many hours, and in some
cases, iron has been transported many miles to the steelmaking plant.

The bottle cars shown here are relatively small, with just 2 six-wheel
trucks. Four truck, 200 ton cars are quite common. The center part
rotates on the end bearings to dump the load into the steelmaking furnace.

The casthouse workers, or "melters" monitor the progress of the pour,
and prepare to divert the iron flow into the next car. They are wearing
insulated, reflective silver coveralls, and hoods with dark eye protection.
Even then, they stay as far away from the "hot metal" as possible.
A pinhole stream of hot metal from a leaking vessel will slice a man in
half instantly.

The molten iron flows through open channels or runners in the casthouse
floor, and is directed by simple gates lowered into the runners.
Originally, the iron would be cast into "pigs" in molds in the floor,
which then needed to be remelted at the steel furnace. The development
of insulated cars allowed keeping the iron molten, significantly reducing
the energy requirements.

The dominant impressions of a blast furnace are the intense heat and noise.
There is a continuous roar of the hot air blast being blown into the bottom
of the furnace, and frequent pounding and banging noises, which produce a
long, reverberating echo in the casthouse.


THE PROCESS

To be useful, the elemental iron must be separated (reduced) from the oxygen
by a high temperature chemical process. At the same time, the rocks and
other minerals mixed in the ore are separated by the fact that the pure
iron is heavier than most other minerals, and melts at a lower temperature
than most rocks. Thus, a pool of molten iron forms at the bottom ("hearth")
of the blast furnace, and is drawn off ("Tapped") every few hours through
the "iron notch". The slag floats above the iron, and is removed via the
"slag notch" or "cinder notch". The reduction process takes place over
a period of many hours, while being levitated by a continuous blast of
hot air blown in from below. The temperature of the molten iron at the
bottom of the furnace is about 3500 degrees F. The slag byproduct is used
in roadbuilding and other construction.

Once pure Fe iron is obtained, it can be used as is, or combined with other
elements, carbon, nickel, chromium, molybdenum, sulfur, etc, to create the
wide variety of steels we used daily.

The top of the furnace is sealed, with an air lock for the addition of
materials, and enormous pipes to collect the large volume of exhaust gasses
from the top. The exhaust consists of low grade fuel gas, which is used to
heat the hot blast stoves, and for other uses within the plant, and
iron dust, which can be recycled.

These complex processes were perfected by slow experimentation, long
before the existence of atoms and elements was known.

Iron is one of the few elements which forms several stable oxide compounds,
each of which has its own unique properties. In many cases, blast furnaces
were customized to handle a particular form of iron ore, and could not
efficiently switch over to a different type.

This scene shows a furnace battery of the Cleveland - Pittsburgh
region as it would have looked approximately 50 years ago.

In this region, the word "blast" is optional, they are just "furnaces".
A furnace will operate non-stop in a "campaign" lasting 7 to 10 years,
and is then shut down for relining, repair, and modernization. Modern
furnaces are heavily instrumented to optimize metal quality and fuel
consumption.

Most early furnaces had womens' names, like early ships.

These furnaces primarily use iron from the Mesabi (Missabe, Mesaba) range
in Minnesota, transported by huge "ore boats", (they are "boats", not "ships",
even though they can be up to 1000 feet long), and by rail at the two ends
of the journey. The scale of these operatations is huge, although increased
recycling and imported steel have reduced the scale significantly in recent
years.



DESCRIPTION OF HOW THIS IMAGE WAS CREATED: 


This is all CSG, in standard POV-Ray 3.01.

It was intended primarily as an exercise in textures and composition,
with no image maps used.

Unfortunately, a complete furnace battery was modeled before I realized that
the scene I wanted only showed a small portion of the model. I will post the
complete furnace and some details on my web site soon.

This furnace is a synthesis of many American units. American furnaces have
a rigid, free-standing shell, while most European furnaces are hidden within
an exoskeleton, which reduces the visual impact.

No two furnaces are identical, since each one is built and updated at
different times, following the needs and practices of the time. I have a
photo of a battery of 10 furnaces side by side, each one different. However,
within one plant, the individual furnaces may have a family resemblance.

I didn't have as much dimensional data as I would have liked, so I scaled
the size of the furnace based on known dimensions, and photos containing
people and objects of known size. Basically, they are really big!

In most cases, the hot metal cars are loaded below the casthouse floor,
out of sight. However, some furnaces, such as the Ford Motor RIver Rouge
Plant, and some older plants in Youngstown, loaded the cars out in the
open as shown here. Several years ago, I watched and photographed this
loading operation at RIver Rouge, from the public street that runs next to
the plant.

I opened up the walls a bit more than usual to allow viewing the interior.
Casthouses are designed with a great deal of ventilation, to allow the heat
to escape, but must prevent rain from getting the runners wet. If hot metal
hits a wet container, a huge steam explosion results. This sort of accident
happens periodically, with significant loss of life.

Another furnace can be seen in the distance at left, over 2100 feet away,
showing the huge size of these things. WIthin a normal battery, blast furnaces
are lined up along the elevated supply tracks, located directly behind the
camera, so the adjacent furnace is out of the scene to the right. In the upper
right corner of the image is the inclined skip car track, which takes the raw
materials to the top of the furnace.

A good example of the usual arrangement of facilities can be seen at the end
of the first Robocop movie, where the fight takes place on the material
stock piles, with the typical overhead crane and clamshell bucket.

The bottle cars are CSG, with rather complex 6 wheel Buckeye trucks that I
had made for the steam locos in the Night round, but ended up not using.

I made up a simple 0-6-0 switcher to fill in the left corner. In positioning
the switcher and empty bottle car, I ran into a limitation of halos, in which
intersecting halos appear to produce a black area at the intersection.
So I turned off the halo on the empty car.

Locomotives are normally uncoupled from cars being loaded, to avoid the
possibilty of moving the cars accidentally, causing a dangerous spill.

The ladle hanging from the crane is not used in normal operations,
but stands by in case there is an excess of hot metal, or other problems
in the pour. The crane is also used in cleaning up the debris in the runners
between casts.

It was getting down to the wire on the final render, so I reduced the number
of samples on the halos to 2. Due to the chaos of the smoke and steam,
reducing the halo samples didn't seem to hurt the image quality.

I had to use a pretty steep antialias, at 0.1, but still have a couple of
minor artifacts.

I benchmarked the render time on 2 machines:

        P120 64MB 28 hours 30 min 16 sec AA 0.1
        P300 40MB  6 hours 16 min 5 secs AA 0.1

Scene contains 3326 objects.


