Environmental Engineering Reference
In-Depth Information
Table 9.10: Composition of abrasive and alloy from CoMo/Al 2 O 3 [From ref. 564 . Reprinted with
permission].
Abrasive (wt.%)
Alloy (wt.%)
Fe 2 O 3
0.10
Co
26 . 9
CoO
0.15
Mo
62 . 0
MoO 3
0.06
S
0 . 04
S
0.04
Fe
5 . 43
C
0.05
Si
2 . 15
SiO 2
0.58
C
3 . 15
MgO
0.05
Al 2 O 3
Balance
abrasive component, it may be used directly in the steel or alloying industry. If the impurities
are present in undesirable amounts, the alloy may be refined in any conventional
manner.
Table 9.10 [564] shows the composition of the abrasive material and the alloy prepared from
roasted spent Co-Mo-Al 2 O 3 catalyst (containing 3.5% Co, 7.7% Mo, 0.05% S, 0.62% Si and
the remainder Al 2 O 3 carrier) using coke as reducing agent (catalyst to coke ratio = 20:1).
In another preparation, the spent catalyst from residue hydroprocessing operation was used.
The roasted catalyst contained, by weight, 3.3% Co, 6.7% Mo, 11.3% V, 3.5% Ni, 0.03% S,
0.54% Si and the remainder alumina. It was mixed with aluminium metal granules and the
mixture (spent catalyst to aluminium metal ratio = 6:1) was melted in a three-phase electric arc
furnace and cooled. The resultant abrasive and alloy components had the following
compositions shown in Table 9.11 [564] . In another patented process developed by Cichy
[565] for the preparation of abrasive alumina from spent catalyst, two furnaces were used for
smelting spent catalyst. The alumina containing slag furnace is transported to a second furnace
for finishing to satisfactory temperature, composition and quality for casting as an abrasive
material or cast refractory.
9.4.3.2 Ceramic Materials
Alumina present in spent hydroprocessing catalysts is converted to fused alumina by a
smelting process at Gulf Chemical and Metallurgical Corporation (GCMC). The smelting
process is actually integrated with metal recovery operations at GCMC for complete recovery
of all useful products (i.e. metals and Al 2 O 3 ) from spent catalyst wastes [566,567] . The
alumina residue, containing the unleached metals left over after removing the metals (Mo
and V) from the spent catalyst by roasting with Na 2 CO 3 and leaching processes, is mixed with
a reductant material and melted in an electric arc furnace to produce fused alumina for ceramic
 
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