Appeal No. 96-2884
Application No. 08/181,997
In the two-step process, Okamura, like appellant, contacts iron oxyhydroxides,
e.g., geothite, hematite and magnetite, with a reducing agent containing no carbon to form
an iron compound. Typical examples of a reducing agent containing no carbon atom are H2
and NH NH , etc. (see column 2, lines 62-63). The contact temperature, contact time, gas2 2
flow rates and other conditions in the first step are said to depend on production history, etc.
(column 3, lines 34-39). Okamura teaches that the iron compound from the first step is then
treated with a reducing and carbonizing agent containing carbon or a mixture thereof with a
reducing agent containing no carbon. As useful reducing and carbonizing agents, Okamura
identifies eight classes of compounds which include both CO and methane. Okamura also
identifies particularly preferable reducing and carbonizing agents containing carbon to
include CO, CH OH, HCOOCH , saturated or unsaturated aliphatic hydrocarbons having 13 3
to 5 carbon atoms. Contact conditions are suitably selected (see column 1, lines 37-41,
column 2, line 64- column 3, line 17-20, lines 48-55). Okamura indicates that his process
produces particles composed substantially of iron carbide alone, or iron carbide in
combination with iron oxide and/or elemental carbon (column 4, lines 35-39). Okamura
shows in his examples, the use of CO (Ex 1), methane (Example 3) and combinations of
reducing and carbonizing agents (Example 13 where he employs propane and methanol) in
the second step.
Stephens is also directed to a two step process for producing iron carbide.
However in the first step, any (Fe O ) iron oxide is oxidized to Fe O the hematite form of3 4 2 3,
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