TITLE:
Method for preparing high-silicon manganese alloy and its refining route.
FIELD OF INVENTION:
The present invention relates to a method of producing low carbon high silicon manganese alloy.
Further, the invention discloses a one-step method for production of low-carbon/micro-carbon
manganese-silicon alloy by sing flux based method using induction furnace, which belongs to the
technical field of ferrous metallurgy. The method comprises of enriching the silicon content of
manganese-silicon alloy by addition of silicon as ferrosilicon to promote formation of silicon
carbide as separate phase and hence it lead to lowering of carbon content of final manganese-
silicon alloy. Fluxing is maintained and hence leads to form slag with a basicity of 0.7-0.8 in
order to control manganese in the alloy and maintaining a slag to metal ratio of 1.2.
BACKGROUND OF INVENTION
Manganese-silicon alloy due to its high applicability in steelmaking is required and quality
control is mandatory due to its high silicon content, which makes the process route complicated.
High silicon manganese alloys for example, Mn65Si25, Mn60Si27 Mn60Si28, and other types of
high silicon manganese alloys. Generally, silicon manganese is produced by predominately
reduction of manganese and silica by carbothermic reduction of form manganese-silicon alloy.

But, when compared with high silicon silico manganese, there is stringent requirement of lower
carbon content. Due to high silicon content in the alloy, there lies a difficulty of production as
compared to conventional silico manganese alloy due to following problems associated which
are: first, the unit power consumption is higher which leads to higher cost; second, in the process
of smelting high manganese alloys of silicon, the silicon reduction is an endothermic process and
higher temperature favour the reduction of silicon but the thorn which formed around the
electrode easily causes the fire phenomenon and hence furnace becomes difficult to be
controlled; third, manganese loss in slag and fumes; fourth, difficult to control the content of the
carbon which affects the yield of alloy. Therefore, high silicon manganese alloys are considered
in the art is a difficult production of ferroalloy products, high technology operational
requirements. Thus, to find low power consumption, high yield, easy to control the furnace
conditions of low carbon content and high silicon manganese alloys production process is
necessary by alternative route with all advantages in place.
Due to involvement of high silicon in manganese alloy and high difficulty involved, not many
manufactures are there to produce this end alloy product with more than 22 wt. % Si. Few
patents describe the process route and its specifications along with its raw material to produce
these high silicon manganese alloys. CN100572575Cdiscloses the process route for reduction
and smelting of iron free manganese oxide (predominately Mn304 and MnO) obtained from
leaching of manganese ore. The manganese oxide is reduced by addition of silicon from

ferrosilicon and lime is added as flux in the process to make a briquette. The method follows two
slag practices, where first slag has basicity of 0.8-1.0 which removes most of the impurities from
lime and ferrosilicon and second slag has basicity of 1.0-1.2 which removes the carbon along
with other impurities in slag. Alloy obtained from second refining stage contains carbon less than
0.4 wt %.In another patent application CN101962704Bdescribes the process method for high
silicon manganese-silicon alloy with low phosphorus, low sulfur and low carbon content by
method of core-wire injection. The process describes the phenomenon of carbon, P and S
removal by reaction of silicon, calcium and magnesium from core wire which is feed to the alloy
at a specific speed. The alloy obtained after treatment is having 0.03 to 0.08 percent of
phosphorous and 0.01 to 0.03 percent of sulfur along with 0.4 wt. % carbon in alloy.
CN102181639B describes the process for carbothermic reduction of silicon and manganese in
submerged arc furnace to produce silicon rich manganese alloy. During the process, slag basicity
is maintained between 0.6-0.8 during the smelting with pole center circle power density of
furnace between 1,600 and 2,200 kVA/m<2>, the secondary current-voltage ratio of between
300 and 450 and the furnace hearth depth which is two times of the diameter of an electrode.
CN102766775B provides the details of two step method for producing high silicon manganese
alloy via submerged arc and shaking ladle route. In this process, 35% manganese ore with Mn:Fe
5.8,28-32% silica are smelting in electric furnace to produce alloy of manganese with 17-20% Si
with 2.5 % C. This alloy is subjected to shaking ladle for further processing with lime and flakes

of silicon and subjected to equilibrium to obtain an alloy with 58 wt. % Mn, 22-25 wt % Si and
0.2-.4 wt. % C.A similar method for production of the alloy has been described by
(CNI03526066B, CN103691925 and CN103710543) to utilize the ladle based method to
produce manganese silicon alloys with silicon and slagging practice. As can been reviewed from
the prior art references that most of the inventions have been using two slag practice with
addition of silicon with lime based slag at basicity of 1.2 for second slag and first slag with 0.6
basicity. None of the patent has analyzed the effect of recycling of ferromanganese slag as flux
material and boron based slag for second slag practice. Therefore, this patent focuses on this
aspect of fluxing of second stage of silicon enriching in standard ferromanganese alloy with
ferrosilicon with addition of ferro manganese slag, lime and boron based compounds to maintain
basicity with 22 wt % Mn in final slag.
OBJECTS OF THE INVENTION:
An object of the present invention is to produce a low carbon high silicon manganese alloy.
Another object of the present invention is to design a single step method to produce high silicon
manganese alloy.
Further object of the present invention is to prepare a method to produce high silicon manganese
alloy but is easy to operate.

Still further object of the present invention is to propose a method of producing high silicon
manganese alloy suitable for industrial continuous production.
Yet another object of the present invention is to propose a method of producing high silicon
manganese alloy which has low energy consumption and is also cost effective.
BRIEF DESCRIPTION OF THE INVENTION:
This invention relates to a method of producing low carbon high silicon manganese alloy
comprising:
blending manganese ores to make Mn/Fe ratio to be 4.6-5.2 of 30-35 wt.%,
the silica mass content of 28-32% and additional dolomite 10-18 wt.%,
subjecting the said manganese ores to the step of smelting by addition of coke to the charge
mixture,
heating the said charge mixture in a furnace to a temperature of 1500-1700°C,
tapping the alloy with the removal of slag,
removing carbon from the manganese alloy by injecting lime-ferrosilicon based mixture to
obtain an alloy having Mn51-53, Si 22-25, C0.8 to 1.2% & P 0.2 to 0.22%,
subjecting the said manganese alloy to treatment of silicon by using ferrosilicon lumps to remove
carbon in the form of silicon carbide,
casting and solidification the alloy to produce the final product which contains 53-55 wt% Mn,
23-26 wt% Si, 0.3 to 0.5% carbon.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1. Shows the micrographs for equilibrium between SiMn and FeSi (a) and (b) are the
sample obtained from equilibration after 15 and 120 minutes respectively at 1600°C
Figure 2. shows the XRD pattern for the SiC obtained from tube furnace equilibrium
experiments
DETAILED DESCRIPTION OF THE INVENTION:
The present invention is achieved by operating two electric finances or one electric and induction
furnace to produce a high-silicon alloy silicomanganese. In this process, manganese ore Mn:Fe
4.2-4.6 of charge mixture comprising of manganese ore and ferromanganese slag are reduced
and smelted in arc furnace to obtain an alloy of manganese and silicon with 2.5 % carbon are
mixed with liquid ferrosilicon of composition is required: Si> 65%, P<0.04%, S<0.02% obtained
from other parallel furnace are blended in the ladle along with added dephosphorization
desulfurization agent along with slag layer of ferromanganese slag. This liquid mixture is
allowed to be equilibrated with churning for 30-35 minutes with supply of external heating

source. The slag is skimmed ofalloy and to be casted to obtain finally a form of high
silicomanganese silicon alloy. The present invention satisfies the domestic and foreign users of
high silicon alloy components Si-Mn Si>22-25%, Mn: 52- 55%, C<0.5%, P<0.1%, S<0.01%
requirement, low production cost, has a very competitive market.
The present invention is to overcome the disadvantages of the prior art and to provide a simple
process, easy to operate, easy to control the furnace conditions, low energy consumption, low
cost, low carbon high silicon manganese alloy production process. The present invention
provides a low carbon high manganese silicon alloys producing method, comprising the steps of:
(1) Preparation of manganese alloy with 2.5 wt % carbon: The production of manganese
alloy with 2.5 wt. % carbon is prepared by blending manganese ores to make a Mn/Fe
ratio of charge to be 4.6-5.2 of 30-35 wt. %, the silica mass content of 28-32 wt. % and
additional dolomite 10-18 wt. % are smelted by addition of 18-25 wt % coke of the total
charge mixture. The blend is continuously feed to the 5000- 30000 KVA submerged arc
furnace which was heated till a furnace temperature of 1500-1700°C and maintaining a
reduction time of 120-150 minutes once released. The alloy is subjected to tap in the ladle
with removal of slag during tapping. The final alloy obtained from this operation have
following components mass percentage Mn60-65 %, Si: 16-18%, C:2.0-2.5 %.

(2) Refining of carbon in manganese alloy: The alloy obtained is subjected to the induction
furnace or ladle subject to the heating requirement, is injected with lime-ferrosilicon
based mixture resulting in removal of carbon from the melt by formation of silicon
carbide by following reactions:

In this process some of the manganese and silicon gets oxidized which eventually reports
to the slag to form Mn-Si-Ca-O slag system and this slag also contains carbon distributed
in the slag. During the operation, a blanking of argon is required to be maintained in order
to prevent any oxygen ingress and to prevent oxidation reactions. The equilibration
reaction of 20 minutes was maintained once after addition of flux. The slag obtained is
subjected to LECO analysis for carbon content and the alloy composition obtained after
treatment is having mass percentage Mn51-53%, Si22-25%, C0.8-1.2 %, P: 0,2-0.22 %.
(3) The alloy obtained is subject to further treatment of silicon treatment by using
ferrosilicon lumps of size 5-10 mm are subject to melting and flux treatment of lime-
ferromanganese slag with 30-35% MnO, 12-16 % A12O3, 25-28 % SiO2, 14-16% CaO, 7-
9 % MgO to maintain an initial basicity of 1.0 -1.1. The present invention adopts the

above process prepared by using silicon manganese alloy prepared by using ferrosilicon
of 70-75 % Si. Secondly, in the process of equilibration more carbon is removed by
formation of silicon carbide formation and reduction of manganese from the slag to
report to the metal and subsequent formation of calcium silicate based melt. Final slag
obtained after treatment of 30 minutes is having basicity of 0.7-0.9. The alloy obtained
after casting and solidification is having: 53-55 wt % Mn, 23-26 wt % Si, 0.3-0.5 %
carbon as final product. Following reactions which occurs during the treatment are given
below:

The present invention is easy to implement and it overcome other prior art furnace conditions
which are difficult to control in step process for enrichment of silicon in the manganese silicon
alloy. Master alloy of ordinary silicon manganese alloy is produced by conventional route as
starting raw material, which is enriched by addition of silicon source and by addition of lime and
ferromanganese slag in two stage practice with removal of in between slag; to increase the
equilibrium coefficient of transfer of carbon as silicon carbide in slag. The method can be usually
followed in ladle with shaking arrangement or in induction furnace which provides eddy currents

in melt bath which results in increase convective mass transfer coefficient. The process
overcomes the difficulties with prior art and can be easily implemented able in large scale
continuous production.
During the method of present invention, the preparation of 1 ton of low carbon high silicon
manganese alloy, ordinary silico manganese consumption of 1.095 tons, with 0.166 tons of
crystalline ferrosilicon (70Si30Fe), 0.105 tons FeMn Slag (22% Mn, basicity: 0.66-0.7) and 0.05
tons lime for production of I ton of final alloy with 52-55 wt % Mn, 22-25 wt% Si and <0.5 wt
% C with power consumption of 18kWh.
In summary, the process of the present invention is simple, easy to operate, easy to control
furnace conditions, low energy consumption, low cost, suitable for industrial continuous
production, to replace the existing silicon carbon high manganese alloys production process.
The specific examples for manganese carbonate as per the flowsheet shown in Figure 1 are
described below.
Example-l
• Preparation of normal manganese alloy: During the preparation of charge, manganese ore
of Mn/Fe: 5.6 of 42 % with particle size of 10-30 mm was added along with 10 % FeMn
Slag with 30 % MnO was added as manganese sources. In the charge, 20% coke with 85
% carbon with 5-10 mm coke was added with 17% quartz with 95% SiO2 and

9.65 mass % dolomite of size of 5-10 mm. Total charge was added in the 50 KVA
submerged arc furnace in continuous mode of charging till 1600°C and the charge was
kept for total of 60 minutes after released. Alloy obtained after smelting is having
Mn61.5%, Si 18.2 %, C 1.75 %, P 0.23 %, Al: 0.32 % and S: 0.005 %.
• About 200 gram of lime and 150 gram of FeSi poured on the molten surface of the
ordinary manganese silicon alloy previously prepared from the first step. The slag and
molten metal was allowed to equilibrate in an induction furnace and mixing happens due
to eddy current in the molten metal. After equilibration for 25 minutes after addition, the
slag from previous stage was removed with addition of mixture of 50 gm FeSi and with
100 gm lime and FeMn slag with 30% MnO with a basicity of 0.8 was added respetively.
This was allowed to equilibrate for another 10 minutes before casting of the alloy with a
composition of Mn 56%, Si 21.5 %, C 0.32 %. The ferro silicon which was added is
having silicon content 70% and CaO content of lime oxide contains 85 %.
Example-2
• Preparation of normal manganese alloy: During the preparation of charge, manganese ore
of Mn/Fe: 5.6 of 37% with particle size of 10-30 mm was added along with 9.4 % FeMn
Slag with 30 % MnO was added as manganese sources. In the charge, 17% coke with 85
% carbon with 5-20 mm coke was added with 26% quartz with 95% SiO2 and

8.69 mass % dolomite of size of 5-10 mm. Total charge was added in the 50 KVA
submerged arc furnace in continuous mode of charging till 1600°C and the charge was
kept for total of 60 minutes after released. Alloy obtained after smelting is having
Mn58.5%, Si 18.2 %, C 1.75 %, P 0.23 %, Al: 0.32 % and S: 0.005 %.
About 200 gram of lime and 200 gram of FeSi in powder form is mixed together and put on the
molten surface of the ordinary manganese silicon alloy previously prepared from the first step.
The slag and molten metal was allowed to equilibrate in an induction furnace and mixing
happens due to eddy current in the molten metal. After equilibration for 25 minutes after
addition, the slag from previous stage was removed with addition of mixture of 100 gm FeSi and
with 50 gm lime and FeMn slag with 30% MnO with a basicity of 0.8 was added. This was
allowed to equilibrate for another 10 minutes before casting of the alloy with a composition of
Mn 58%, Si 22.8 %, C 0.28 %. The ferro silicon which was added is having silicon content 70%
and CaO content of lime oxide contains 85 %.

WE CLAIM:
1. A method of producing low carbon high silicon manganese alloy comprising:
blending manganese ores to make Mn/Fe ratio to be 4.6-5.2 of 30-35 wt.%,
the silica mass content of 28-32% and additional dolomite 10-18 wt.%,
subjecting the said manganese ores to the step of smelting by addition of coke to the charge
mixture,
heating the said charge mixture in a furnace to a temperature of 1500-1700°C,
tapping the alloy with the removal of slag,
removing carbon from the manganese alloy by injecting lime-ferrosilicon based mixture to
obtain an alloy having Mn51-53, Si 22-25, C0.8 to 1.2% & P 0.2 to 0.22%,
subjecting the said manganese alloy to treatment of silicon by using ferrosilicon lumps to remove
carbon in the form of silicon carbide,
casting and solidification the alloy to produce the final product which contains 53-55 wt% Mn, 23-26
wt% Si, 0.3 to 0.5% carbon.
2. The method as claimed in claim 1, wherein in the step of smelting 18-25 wt% of coke of
the total charge mixture was added.

3. The method as claimed in claim 1, wherein the said charge mixture is fed to the 5000-
30.000KVA submerged arc furnace at 1500-1700°C maintaining a reduction time of 120
-150 minutes once released.
4. The method as claimed in claim 1, wherein the said lime-ferrosilicon removes carbon
from the melt by formation of silicon carbide by following reaction:

5. The method as claimed in claim 1, wherein treatment of ferrosilicon lumps cause removal
of carbon and reduction of manganese from the slag and the reaction is as follows:
SiC(s)+MnO(slag)=SiO2(slag)+3Mn(g)+CO(g) ΔG° = -963120 - 474T (J/mol) [2]
SiC (s) + MnO(slag) = SiO(g) + Mn(g) + C22-ΔC0 = -605630 - 276T (J/mol) [3]
SiC(s) + 2SiO2(slag) =3SiO(g) + CO(g) [4]