Mineral Facts and Problems: 1960 Edition Page: 377
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HAFNIUM
By Charles T. Baroch1
AFNIUM, the latest arrival of an interesting triad of metals, was born
as an outcast of the Atomic Age and did not stir the popular fancy as
did its sister metals titanium and zirconium, but better knowledge of its
properties has led it to an honored place in the new science of atomic energy.
SUMMARYHafnium always occurs in zirconium miner-
als and is recovered as a byproduct of hafnium-
free zirconium. Production is from zircon,
which is in ample domestic supply and has
large reserves, and from 1 to 3 pounds of haf-
nium are recovered for each 100 pounds of
zirconium. Ductile zirconium metal was first
produced by the Federal Bureau of Mines in
1945, but it was not until about 7 years later
that a method of removing the hafnium was
perfected.
The separation of hafnium from zirconium
is a complex and expensive operation, and sol-
vent extraction is a preferred method. The
Bureau began producing hafnium-free zir-
conium in 1952 and hafnium metal shortly
thereafter.
At present, hafnium has only one significant
use-as a neutron absorber for controlling nu-clear reactors. For this purpose, hafnia is
reduced to sponge metal by the Kroll process
used for zirconium-sponge production. Sponge
hafnium is currently produced only by the
Wah Chang Corp. from hafnium oxide and
hydroxide produced under Atomic Energy
Commission (AEC) contracts for Reactor-
grade zirconium with three other companies.
The sponge hafnium is refined by the iodide
process by Foote Mineral Co. Present pro-
ductive capacity for sponge is about 65,000
pounds a year.
Hafnium problems are: Its high cost of
production compared to possible substitute ma-
terials, dependence of its production as a by-
product of Reactor-grade zirconium, a vul-
nerable market because of only one major use,
and a large number of technologic production
and fabrication problems.]BACKGROUND
Hafnium is a minor constituent in all zir-
conium minerals and is chemically so similar
to zirconium that positive identification was
not made until 1922. Zirconium compounds
prepared prior to 1924 contained all the haf-
nium that occurred with the zirconium (5)."
The Bureau of Mines began developing the
Kroll process for producing ductile zirconium-
hafnium metal in 1945, and a pilot plant capa-
ble of producing 60 pounds of metal a week
was started in early 1947. The AEC and the
Navy Bureau of Ships became interested in
the metal, and production capacity increased
to 5,000 pounds per month by October 1950 and
nearly 25,000 pounds by September 1952. (6)
Up to 1950 the hafnium was not removed from
1 Chief, Branch of Rare and Precious Metals.
2 Italicized numbers in parenthese refer to items In bibliog-
raphy at end of chapter.the zirconium, as the hafnium content does not
detract from many uses of zirconium. How-
ever, for nuclear uses, hafnium in zirconium
is detrimental, because the presence of hafnium
increases the neutron absorption cross-section
of zirconium greatly and makes it less desir-
able as a structural material in reactors.
After 2 years' work sponsored by the AEC
at Oak Ridge, Tenn., a solvent extraction
process was developed for the separation of
zirconium and hafnium. The Bureau con-
structed a purification plant utilizing this
process and began producing high-purity, low-
hafnium (Reactor-grade) zirconium in March
1951. Later the Bureau began producing
high-purity hafnium sponge in a plant which
attained a capacity of 7,000 pounds of haf-
nium and 300,000 pounds of zirconium by the
end of 1953.
377
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United States. Bureau of Mines. Mineral Facts and Problems: 1960 Edition, report, 1960; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc38790/m1/385/: accessed April 23, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.