Note: Descriptions are shown in the official language in which they were submitted.
200816~
The present invention relates to a method and
apparatus for manufacturing high-grade nickel matte in a
combination of suspension smelting furnace and electric
furnace .
Conventionally high-grade nickel matte i8
manufactured from sulphidic concentrates as follows: first
the concentrate is dried and smelted in a suspension
smelting furnace to form nickel matte. The nickel matte
thus obtained i6 further converted to high-grade nickel
matte, where the c~ ' in~d content of nickel and copper is
72-75% by weight, for instance in a Pierce-Smith type
converter. In addition to this, the slag from both the
suspension smelting furnace and the converter is cleaned in
an electric furnace, from which the obtained matte is
le~uLlle-l as feed to the converter. The gases created in
the process, both from the suspension smelting furnace and
from the converter, are collected and used in the
production of sulphuric acid.
The above described conventional method for
manufacturing high-grade nickel matte is reliable and has
been tried and found adequate, but it also has some
drawbacks. Such drawbacks are for instance its high
investment costs. Iqoreover, the process forms two
different gas flows, of which one (the converter gas flow
based on the blasting technique) is highly variable in
quantity, which makes the gas treatment and sulphuric acid
production expensive. The use of the converter also leads
to problems with smoke in the working areas, because the
converter hood must be shi~ted at different stages of the
converting process. Furthermore, the process requires
shifting of the molten material from the suspension
smelting furnace into the converter, and from the converter
to the electric furnace as well as from the electric
furnace to the converter. For the above described reasons,
the process results in a large amount of intD ~ te
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products, which again cause expenses in their treatment,
smelting and cleaning.
An obj ect of the present invention is to
eliminate some of the drawbacks of the prior art and to
provide a better and simpler method for manufacturing high-
grade nickel matte, as well as an apparatus suited for the
method .
Accordingly, one aspect of the invention provides
a method for manufacturing high-grade nickel matte, which
comprise6: a) feeding a concentrate under treatment,
together with flux, recirculated flue dust and oxidizing
gas into a suspension smelting furnace, b) forming a slag
and high-grade nickel matte in the suspension smelting
furnace, c) conducting at least the slag from the
suspension smelting furnace into an electric furnace, where
it is reduced, in the presence of a reducing agent, so as
to form electric furnace slag and metallicized matte, and
d) returning at least part of the metallicized matte from
the electric furnace as feed to the suspension smelting
furnace.
A further aspect of the invention provides an
apparatus for carrying out the method, which comprises a
suspension smelting furnace for smelting the material and
an electric furnace for treating the molten material.
In the manufacturing method of high-grade nickel
matte according to the present invention, there is produced
high-grade nickel matte in a suspension smelting furnace,
such as a flash smelting furnace. As a result of the high
nickel content of the high-grade matte, and the high oxygen
potential of the furnace, the nickel content of the slag
from the suspension smelting furnace is also high. the
slag from the suspension smelting furnace is reduced in an
electric furnace, which is either separate or connected to
the suspension smelting furnace by a special separating
member. If desired, at least part of the high-grade nickel
matte can also be fed into the electric furnace. The matte
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3 2~81B7
created in the electric furnace is at least partly
recirculated back to the suspension smelting furnace. The
recirculated matte, which is fed into the suspension
smelting furnace either as a granulated product or molten,
further reduces the slag from the suspension smelting
furnace, and simultAneollqly ~limin;~h~ the amount of the
recirculated material. Thus, the method and apparatus of
the present invention for manufacturing high-grade nickel
matte make it possible to eliminate the use of the
converter as one process stage.
Conc~ ntly, the method for manufacturing high-
grade nickel matte of the present invention leads to
remarkable advantages in comparison with conventional
technique. While using granulated matte from an electric
furnace as the feed for the suspension smelting furnace, it
is unnecessary to shift molten materials in the
manufacturing method of the present invention, and as a
result smoke problems in the working area are essentially
reduced. Accordingly, there are essentially no
into ~ te products ~ormed in connection with the
manufacture of high-grade nickel matte. Furth,~ e,
according to the invention there is created only one
essentially even gas flow, which lowers the cost of
sulphuric acid production and of gas treatment.
While applying the method and apparatus for
manufacturing high-grade nickel matte of the present
invention in a new production unit, the space and other
facilities required by the converter can be excluded from
the very beginning. This makes the production unit more
compact and essentially cheaper in investment costs, as
compared to the prior art equipment. Accordingly, the
demand for labour is reduced owing to the manufacturing
method of high-grade nickel matte of the present invention.
The manufacture of high-grade nickel matte
according to the present invention can also be applied to
an existing production unit, because the technology used in
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4 2Q08167
the method i6 known as such. However, in the manufacturing
method of high-grade nickel matte of the present invention,
both the coupling of the equipment together and the method
for running the high-grade nickel matte production are
5 essentially different from those of the prior art.
r ~ ?nts of the invention will be described in
more detail below, with reference to the appended drawings,
in which:
Figure 1 is an illustration of a preferred
10 embodiment of the invention, seen in a side-view cross-
section, and
Figure 2 is an illustration of another preferred
embodiment of the invention, seen in a side-view cross-
section .
According to Figure 1, into the reaction shaft 2
of a suspension smelting furnace 1, there is fed oxidizing
gas 3, flux 4, concentrate 5 and matte 6 formed in an
electric furnace, as well as flue dust 7 obtained from the
cooling 21 of exhaust gases. The gases created in the
suspension smelting furnace 1 are removed through uptake
shaft 8 to gas treatment in a gas cooling system 21. Slag
9 from the suspension smelting furnace 1 and produced high-
grade nickel matte 10 are removed from settler 11
respectively through discharge hatches 19 and 20.
The slag 9 from the suspension smelting furnace
is further conveyed to an electric furnace 12, where the
61ag 9 is reduced by means of coke 13 used as the reducing
agent. As a result of the reduction process, there is
created slag 14 and metallicized matte 15, which are
removed from the electric furnace 12 respectively through
the discharge hatches 16 and 17. The metallicized matte 15
is subjected to granulation 18 after removal from the
furnace. The granulated matte 6 is returned as feed to the
suspension smelting furnace, for the production of further
high-grade nickel matte.
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5 2008167
According to Figure 2, the suspension smelting
furnace 1 and an electric furnace 22 are interconnected so
that in between the suspension smelting furnace 1 and the
electric furnace 22 there is installed a partition wall 23,
which prevents the molten high-grade nickel matte 10
produced in the suspension smelting furnace 1 from flowing
into the electric furnace 22, but allows the slag 9 from
the suspension smelting furnace to flow as an overflow into
the electric furnace. The partition wall 23 can be formed
of one piece, in which case the wall 23 is common for both
the suspension smelting furnace 1 and the electric furnace
22, or alternatively of two pieces, in which case the
sections of the wall 23 adjacent the suspension smelting
furnace 1 and the electric furnace 22 are separate, and
there is formed a connecting duct 24 in between the walls.
The following Example illustrates the invention.
Exam~le
The method of the invention was applied to a
sulphide concentrate, which contained 6.9~6 by weight
nickel, 1.2% by weight copper, 36.3% by weight iron, 26.5%
by weigh sulphur and 11. 5% by weight silicon oxide. The
concentrate was fed into the reaction shaft of a flash
smelting furnace, and for each ton of concentrate there is
also fed 82 kg of matte from an electric furnace, 230 kg of
flux, and 98 kg of flue dust separated from the exhaust
gases from the flash smelting furnace. In addition to
this, there was fed 320 Nm of oxidizing gas with an oxygen
enrichment degree of 80% into the reaction shaft per ton of
concentrate fed therein.
The product obtained from the settler of the
flash smelting furnace was high-grade nickel matte
containing 65% by weight of nickel, 10% by weight of copper
and 22% by weight of sulphur. Moreover, from the settler
of the flash smelting furnace there was obtained slag
containing 3% by weigh of nickel, 0.6% by weight of sulphur
and 30% by weight of silicon oxide.
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200816~
The slag from the flash smelting furnace was
further cu..v~yed to an electric furnace, where the slag was
reduced by means of coke. In the reduction there was
formed a slag phase and a metallicized matte phase, which
5 in connection with the removal from the electric furnace
was granulated and returned as feed to the flash smelting
furnace. On the basis of the slag from the electric
furnace, which contained 0.1596 by weight nickel and 0.17%
by weight copper, it was observed that, with the method of
10 the present invention, the obtained recovery rate of the
nickel that was fed in the concentrate was 97 . 996 .
