General covered hopper questions (Was: Re: Frisco PS2)


--- In, Tim Gilbert <tgilbert@...> wrote:
Powdered Petroleum Coke or Carbon Black shipped in bulk may be
derivatives requiring covered hoppers although maybe not on the

Tim Gilbert
Tim -

I do not think petroleum coke was shipped in powdered form - at
least not deliberately! It was a "waste product" to refiners whose
feedstock oil had too much carbon and too little hydrogen in
molecular makeup. Immediately after it was made, it was cut out in
chunks - was not powdery - at the delayed coking unit in a refinery,
and placed into hoppers. It was sold for fuel, but it had high
amounts of heavy metals (vanadium) and sulfur in it, so it could not
be burned in just any combustion device. They just wanted it off
the property. I have only seen it shipped in open hoppers and
stored in piles outside at the destination. It is not particularly
dusty either. I do not think it was ever shipped in covered or
roofed hoppers.

Carbon black is another matter! It is peculiar stuff. There are
many types of carbon black - most is and was used for automobile
tire manufacture, but some (in the germaine time period) was used
for making carbon paper, inks, printing ink, typewriter ribbon,
pigments for paint, etc. Each end use requires a different type of
carbon black - different in its microscopic structure, as determined
by the burner configuration. It is, in general, made from
incomplete combustion of heavy ends with a high aromatic content.
Its manufacture is an art as much as it is a science. The design of
the burners is a closely guarded confidentiality in most companies
that make it. Not all heavy oil is suitable for making carbon
black. The oil is so specific to the type of carbon black being
made that some plants have it delivered in tank cars from remote

Carbon black, in the pre-1960 time period was shipped in special
privately owned large covered hoppers in VERY captive service.
These cars are recognizable - they are always black(!) and were very
much larger than the usual 29' covered hopper fleet of the pre-1947
era. I also saw some bathtub-shaped cars in this service - they
held two or three large rubber bladders. They were used at the
carbon black plant near Aransas Pass, Texas (still there). They
were singularly ugly cars. I never saw one with empty bladders -
only with them inflated. Carbon black is a very light commodity,
but it has to be kept free of impurities that would mess up its
further processing. There must have been (in the 1950's) at least
25 additives and extenders added to a batch of carbon black and
styrene-butadiene copolymer to make a tire. With the advent of
fiberglas belting, then steel belting, there are more today - like
the surfactants that bond the solid-solid interface of the steel-
rubber to prevent tread separation, etc. Carbon black was shipped
from Texas to Akron, Ohio for tire manufacture, so the cars could be
seen in transit between the these locations.

A.T. Kott

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