United States. Patent [19]
Stephens, Jr.
[11]
[45]
4,398,945
Aug. 16, 1983
6 Oaims, 1 Drawing Figure
3,656,934 4/1972 Curlook 75/82
3,947,267 3/1976 d'Entiemont et at 75/130.5
3,999,981 12/1976 Brandstatter 75/84
4,053,301 10/197'7 Stephens, Jr 75/11
4,256,496 3/1981 Brandstatter 106/43
Primary Examinf!r-L. Dewayne Rutledge
Assistant Examiner-Christopher W. Brody
The object of the invention is to provide a process for
the recovery of iron and nickel from low iron content
laterite ores.
Said process comprises subjecting the ore to a carburizing
step in the presence of a reducing agent and carbon
supplying agent to convert the iron to iron carbide,
followed by smelting the residue or product of the carburizing
step to produce a ferronickel product.
An alternative embodiment is the recovery of the iron
and nickel from the product of the carburizing step by
magnetic separation.
[54] PROCESS FOR PRODUCING A
FERRONICKEL ALLOY FROM NICKEL
BEARING LATERITES
[7§] Inventor: Frank M. Stephens, Jr., 12225 W.
18th Dr., Lakewood, Colo. 80233
[2J] Appl. No.: 276,040
[22] Filed: Jun. 22, 1981
[51] Int. 0.3 C21C 5/52
[52] U.S. O 75/11; 75/26;
423/148
[58] Field of Search 75/11, 10 R, 26, 80,
75/82, 84; 423/138, 148
[56] References Cited
U.S. PATENT DOCUMENTS
2,473,795 6/1949 Hills et aI. 75/82
2,740,710 4/1956 Johannsen 75/133.5
3,077,396 2/1963 Moussoulos 75/31
3,502,461 3/1970 Guttier et aI. 75/10
3,503,735 3/1970 Beggs et aI. 75/31
3,634,064 111972 Vedensky 75/31
[57] ABSTRACf
ORE
H2 +CH 4 0R CO
--,
II
-,-- --,
GNETIC I
ATMENT I
____ ...J
"')
CARBIDE
CONVERSION
f---.;;';"'-
, ,_.-
ARC FURNACE Fe .J MA
MELTING ·Ni I TRE L __
"
HEATSLAG
FER RONICKEL
U.S. Patent Aug. 16, 1983 4,398,945
ORE
H2 +CH 4 OR CO
--,
I
I -,-- --,
GNETIC I
ATMENT I
____ -.J
CARBIDE
CONVERSION
f.--- --
r---
ARC FURNACE ..fe..J MA
MELTING Ni I TRE
L __
HEATSLAG
FERRONICKEL
1
4,398,945
2
0.7
5.J
4.3
WI. %
%
17.4
1.5
23.3
23.0
0.7
Ni
H20
AhO]
18.7
27.2
27.3
wt.%
Fe
C
MgO
Si02
Ni
Fe
MgO
Si02
EXAMPLE 2
A sample of the residue from Example 1 was separated
magnetically using a 15-gram sample as feed to a
Davis tube separator. The Davis tube products were
analyzed for iron as iron carbide and nickel and were
examined by mossbauer spectroscopy to determine the
mode ofoccurrence ofthe iron. The results showed that
a magnetic fraction can be separated and that its iron
assay will be about 45 percent and its nickel assay about
1.4 percent. This represents a significant grade improvement.
EXAMPLE 3
A lOO-gram charge of the residue or product of Example
1 was melted in a Deltech furnace. The product
had a melting temperature of about 1550· C. and upon
melting formed a metallic button and a slag cover.
The metallic button contained 79.9 percent iron and
2.95 percent nickel; whereras, the slag assayed 0.95
percent of iron and 0.005 percent nickel. This represents
a significant recovery of iron and over 99 percent of the
contained nickel in the metallic button.
The results show that a feasible and technically efficient
process has been developed based on the. partial
conversion of iron to iron carbide in low iron laterities
followed by smelting to produce ferronickel.
5
The iron oxide in the sample of nickel laterite was
converted to iron carbide in a laboratory 4-inch fluidized-
bed reactor. The unit was operated at a temperature
of 550· to 580· C. using gas compositions containing
63 to 69 percent hydrogen as the reducing agent, 10
to 20 percent methane and 12 to 16 percent CO (carbon
monoxide) as carbon supplying agents, and 3 to 12 percent
C02. The temperatures used are dictated by economy
with a preferred range being between about 500·
C. to 700· C. with the preferred upper limit about 700·
C. The above gases can be used within the ratios disclosed
in U.S. Pat. No. 4,053,301. The progress of the
conversion of Fe203 to Fe3C was monitored by submitting
samples of mossbauer and carbon analysis.
After twelve. hours of operation, the carbon content
of the bed material leveled offat 1.5 percent carbon and
the mossbauer analysis indicated that 50 percent of the
iron in the sample had been cOllverted to iron carbide
with the balance being present as iron silicates which
was not converted. This material was removed from the
fluidized-bed. reactor and was used as feed material for
30 testing the recovery therefrom of iron and nickel by
magnetic separation and by smelting. The fluidized bed
residue or product had the following analysis:
65
EXAMPLE 1
TECHNICAL FIELD
BACKGROUND ART
DISCLOSURE OF THE INVENTION
PROCESS F'OR PRODUCING A FERRONICKEL
ALLOY FROM NICKEL BEARING LATERITES··.
Twopyrometallurgical processes are currently in use 20
for the treatment of low iron laterite. In the rotary
kiln-arc furnace process the ore is mixed with coke,
preheated, and partially reduced in the rotary kiln and
the hot kiln product used as feed to an arc furncace
smelting step to produce ferronickel and slag. In the 25
other commercial process, the ore is melted in an arc
furnace arid then mixed with molten ferronickel and
molten ferrosilicon to yield an enriched ferronickel and
slag.
In accordance with the present invention, the nickel
and iron in nickel containing laterite ore are recovered
as a ferronickel product by first reducing and carburizing
the iron oxides to iron carbide in accordance with 35
the teaching of U.S. Pat. No. 4,053,301 with simultaneous
disruption of the ferrite structure of nickel ferrites,
followed by smelting the product in an electric
furnace to product the ferronickel product.
The improved process has the advantage that the 40
product from the carburizing step can be introduced
directly into the electric furnace for smelting to produce
the ferronickel product with high yields of nickel
without the addition of ferrosilicon. Further, the carbu- 45
rized product is magnetic, making possible the magnetic
recovery of iron carbide and nickel from the ore.
The invention relates to the· recovery of· iron and
nickel from laterites. It is difficult to economically recover
iron alone from low iron content laterites without
the simultaneous recovery of some other valuable 10
metal, such as, nickel in nickel containing laterites. It is
difficult to recover the nickel and iron simultaneously
because of the difficulty of disrupting the ferrite structure
of nickel ferrites. Further, a process is desirable for
the direct conversion to a ferronickel product of the 15
iron and nickel in nickel containing laterites, and without
the· use of ferrosilicon, as in· the prior art.
The nickel bearing laterite ore used in this example
had the following composition:
BRIEF DESCRIPTION OF THE DRAWINGS
The single FIGURE of the drawing is a flowsheet of 50
the process.
BEST MODE FOR CARRYING OUT THE
INVENTION
The disclosure of the carburizing process of U.S. Pat. 55
No. 4,053,301 is incorporated herein by reference, including
the use of a fluidized bed, the carburizing temperatures,
reducing and carburizing materials, ratios of
additives, and other critical factors.
THE TERM "laterite ore" as used herein includes all 60
nickel bearing laterite ores of various compositions. The
nickel bearing laterite ore used in the examples was
ground to a fine particle size, typically about - 200
mesh, but this is. not critical.
4~398,945 ..•
30
35
3
The conversion to carbide can be accomplished at
relatively low temperatures using gaseous reductant
produced from low rank fuels and the arc furnace operation
would involve only melting with no electrical
energy or secondary reductant involved for the reduc': 5
tion of nickel.
The results of Example 1 show that substantially all
of the iron present as iron oxides in the laterite ore can
be converted to iron carbide by the present process, but
the iron present as complex silicates cannot be so con- IO
verted, thus illustrating the unpredictability of ores
upon which the process is operative.
Because of the large excess of iron over nickel in most
laterities, it is generally not advisable to convert all of
the iron to ferronickel because the resulting iron-nickel 15
alloy produced in the melt step would have an unfavorably
iron to nickel ratio. The iron to nickel ratio in the
ferronickel alloy product. is controlled by converting
only a portion of the iron in the ore to iron carbide. 20
The invention is not restricted to use on ores or other
materials containing only nickel with iron but can be
used in similar fashion to recover other metals existing
with iron in ores and other materials which metals have
a melting point in excess of 750· C. and which alloy 25
with iron upon smelting. Examples of these other metals
recoverable by the process along with iron are cobalt,
chromium, manganese,' molybdenum, nickel, tungsten,
and vanadium. All of these metals alloy with iron in
steel making processes.
Also, the invention is not restricted to making' the
iron carbide in situ to make the final alloy product. The
iron carbide can be made or obtaind separately and
either part or all that is required added during the processing.
I claim:
4-
1. A process for recovering a metal which has a melting
point in excess of about 750· C, and is'c:apable of
alloying with iron, in the form of an iron alloy from a
material containing iron and said metal, said process
comprising: .
(a) contacting said material with iron carbide, at least
some of said iron carbide being formed by converting
at least some of said iron in the material containing
iron to iron carbide in a fluidized bed in the
presence of a carbon-supplying material and a reducing
agent, and
(b) smelting the product of step (a) to produce the
alloy of said metal with iron
2. The process of claim 1 in which no additional
reducing agent is added to step (b).
3. The process of claim 1 in which said other metal is
selected from the group consisting of cobalt, chromium,
manganese, molybdenum, nickel, tungsten and vanadium.
4. The process of claim 3 in which said other metal is
nickel.
5. The process of claim 1 in which said material containing
iron and said metal is laterite ore.
6. A process for producing an alloy of iron and another
metal, said other metal having a melting point in
excess of about 750· C. and being capable of alloying
with iron, from an ore containing iron and said other
metal, comprising: .
(a) contacting said ore with iron carbide, at least sone
of said iron carbidge being formed by converting at
least some of said iron in said ore to iron carbide in
a fluidized bed in the presence of a carbon-supplying
material and a reducing agent, and
(b) smelting the product of step (a) to produce the
alloy of said metal with iron.
* * * * *
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65