Title: A PROCESS FOR PRODUCTION OF FERROSILICON FROM BANDED
HEMATITE JASPER ORE
FIELD OF INVENTION:
This invention relates to a process for the production of ferrosilicon from lean iron ore such
as banded Hematite Jasper. The invention is particularly relates to a process for smelting
reduction of Banded Hematite Jasper and quartzite in a submerged arc using low reactive
coal as a reducing agent for producing ferrosilicon.
BACKGROUND OF THE INVENTION:
The necessity of ferrosilicon in steel industries is well known. Silicon has got wide range of
application in the production of corrosion-resistant, high-temperature resistant steels and
electromotor and transformer cores. Ferrosilicon is used as inoculants which accelerate
graphitization during the production of cast iron. In arc welding, ferrosilicon is used in
electrode coatings. Ferrosilicon with silicon content up to about 15% is made in blast
furnaces lined with acid fire bricks. The standard method of producing high grade
ferrosilicon is made from the electric arc furnaces and the raw materials used for this process
are quartzite, petroleum coke and silicon steel filings or pure iron (Chinese patent No.
CN1103896-A). Reference may be made patent No: US 4526612 wherein the process
introduced a energy-rich plasma gas reaction chamber for reducing lump form of silica of
98% SiO2, steel scraps and coke or coal with low ash content for manufacturing of
ferrosilicon. Benjamin et al (US 37041147) produced ferrosilicon alloys having 45% to 95%
silicon using blended fine and coarse fraction of silica admixed with particulate iron bearing
material, a coal containing 79.7% fixed carbon with low ash.

Reference may be made of U.S patent No. 3431103 in the quartzite and carbon compound
are introduced to the furnace in the form of briquette or pellets. The binding strength of the
agglomerates were obtained by using different binder like sulphite waste liquor, water glass
etc and subsequent curing in the temperature range of 600 to 1000°C for upto 30min. Both
coking and non coking coal were used at different ratios. In another U.S patent No. 3759695,
finely (-200 mesh) divided iron ore, quartzite and coal are agglomerated in the form of
briquette and then charged into the furnace to obtain ferrosilicon of the grade containing 45-
50% Si. It does not mention the types of binder used. Reference may also been made of two
stage production process for ferrosilicon (U.S patent No. 4898712). In this invention, the
carbon monoxide generated during smelting process was used to pre-reduce the higher oxide
of iron to iron monoxide which results in subsequent saving of both energy and cost.
The processes developed so far as described above have the following draw backs:
1) Required high quality raw materials such as quartzite, petroleum coke, silicon steel
filings, pure iron, and turnings, which increases the cost of production,
2) Insufficient availability of the pure raw materials for production of ferrosilicon,
3) Non-availability of low ash, low phosphorous coking coal making high cost
imperatively
4) In some process, grinding of raw materials is required for agglomeration. Therefore,
binders are also very important and makes process very costly,
5) To obtain sufficient cold handling strength, sometimes curing is also required which
add to the energy consumption.
In world-wide slowly the availability of high grade raw materials are diminishing, therefore it
is necessary to utilize alternative source for the sustainable development. As the existing
resource or reserve is depleting to meet the demand, production of ferrosilicon from such
alternative sources not only enhances the resource base but also results in corresponding
decrease in the requirement of high quality quartzite. Normally, silica is the major impurity
present in the Banded Hematite Jasper (BHJ) sample. To recover iron value, it has to be
crushed and subsequently beneficiated. These ores typically consist of alternative bands of

iron-bearing hematite inter growth with quartz. Therefore, beneficiation of Banded Hematite
Jasper (BHJ) results in low yield and the process would not be economically viable.
Alternative way may be to use it a feed material for the production of ferrosilicon as it has
contain very high level of silica.
In view of aforesaid problems as available in prior knowledge, a process has been developed
for the production of ferrosilicon from an alternative resource like low grade iron ore
containing high percentage of silica as a major impurity. The low reactive carbonaceous
material such as Jhama coal has been selected as a reducing agent for producing ferrosilicon.
The amount of iron-bearing a material in the charge mix was variable and depended on the
percentage of silicon desired in the iron-silicon alloy to be produced. In the present invention,
different proportion of charge mix have been tried to achieve higher recovery of ferrosilicon.
The size of the iron-bearing Banded Hematite Jasper (BHJ) material was about 15 to 20 mm.
The size of the quartzite material was about 12 to 15 mm and the size of the Jhama coal was
about 20 to 25 mm. The Jhama coal in the mix was also a variable since the fixed carbon in it
was varying from 57 to 79% depends on the desired ferrosilicon alloy required to produce.
For example, the fixed carbon of a charge can vary between a minimum of about 57% of the
stoichiometric amount necessary for reduction of all the silica and Banded Hematite Jasper
(BHJ) according to the reaction.
SiO2 + 2C → Si +2CO----(1)
Fe2O3 + 3C → 2Fe +3CO----(2)
For the efficient production of ferrosilicon, 20% excess of the stoichiometric carbon is used
to compensate the burning and other losses during smelting reduction. The energy
consumption for the production of 43% Fe-Si in submerged arc furnace using above charge
mix requires 10800 kWh / ton. In addition, a saving can be realized from a reduction in the
electrode consumption rate is about 100 kg/ton of ferrosilicon.

OBJECTS OF THE INVENTION:
An object of this invention is to propose a process for the production of ferrosilicon from
lean iron ore;
Another object of this invention is to propose a process of utilizing low reactive coal as an
alternative source of reducing agent for the production of ferrosilicon;
Still another object of this invention is to propose a process which improves the grade of
ferrosilicon by using combination of the low reactive coal and pet coke;
Yet another object of this invention is to propose a process which does not require any
agglomeration process and so no binder is required;
Further object of this invention is to propose a process which does not involved any pre-
reduction steps.
BRIEF DESCRIPTION OF THE PRESENT INVENTION:
According to this invention there is provided a process for the production of ferrosilicon from
lean ore comprising the steps of:
grinding the lean ores, low reactive coal, quartzite and pet coke to the size ranging between
10-30 mm;

mixing the said ores, lower active coal quartzite and pet coke in a ratio ranging between
1:1.13:0.63:0 to 1:0:0.97:1.23;
introducing the said mixture in a submerged arc furnace having the temperature in the range
of 1700 to 1900°C for a period of 3-4 hrs;
tapping the materials into the metal moulds.
DETAILED DESCRIPTION OF THE INVENTION:
In the present invention a process has been developed for the production of ferrosilicon from
lean iron ore such as Banded Hematite Jasper. The invention is particularly relates to a
process for smelting reduction of Banded Hematite Jasper (BHJ) and quartzite in a
submerged arc using low reactive coal such as Jhama coal as reducing agent for producing
ferrosilicon. The invention is useful to recover values from Banded Hematite Jasper (BHJ)
and low reactive Jhama coal, which are currently not being used for any of the production
processes in iron and steel sector or alloy steelmaking, and therefore, it is important from the
view point of environmental protection and waste resource utilization. In the present
investigation focused on the production of high grade ferrosilicon using easily and cheaply
available lean ores such as Banded Hamatite Jasper (BHJ), low reactive coal such as Jhama
coal in order to minimize the production cost. The quantity of Jhama coal used for the
reaction is about 20% excess of stiochiometric value. The high gangue material present in the
Banded Hamatite Jasper (BHJ) and high ash and volatile matter present in the reductant
(Jhama coal) have more unfavourable effect on the furnace operation. Quartzite and iron
bearing material such as Banded Hamatite Jasper (BHJ) possibly getting reduced by low
reactive Jhama coal thus the silica being brought to the molten state, being reduced and
dissolve in the iron to form ferrosilicon. With the use of low grade materials such as Banded
Hamatite Jasper (BHJ), low reactive coal such as Jhama coal it is possible to produce high
grade ferrosilicon successfully by this process.

The present invention provides a process for the production of ferrosilicon from Banded
Hematite Jasper which comprises:
i) taking lean iron ores such as Banded Hematite Jasper, low reactive coal, quartzite
and pet coke and grinding them to the size ranging between 10-30 mm and mixing
them in the ratio ranging between 1:1.13:0.63:0 to 1:0:0.97:1.23,
ii) charging the above mixture of raw materials in submerged arc furnace and
maintaining temperature in the range of 1700 to 1900°C for a period of 3-4 hrs,
iii) tapping the materials into the metal mould by known method
In an embodiment of the present invention the used Banded Hematite Jasper (BHJ) may have
composition in range: 52 to 60% Fe2O3, 34 to 48% SiO2, l to 2% A12O3.
In another embodiment of the present invention the used Jhama coal may have may have
composition in range: 57 to 79% Fixed Carbon, 12 to 25% Ash, 5 to 10% Volatile Matter.
In still another embodiment of the present invention the quartzite used may have the
following composition: 97.5 to 98.5%SiO2, 0.2 to 0.3% Fe2O3, 0.2 to 0.4% A12O3.
In yet another embodiment of the present invention the used pet coke may have the following
composition: 91 to 93% Fixed Carbon, 7 to 8% Volatile Matter, 1-2% Ash.
In yet another embodiment of the present invention the used Quartzite may be of commercial
grade.
The present invention is directed to the utilization of low grade Banded Hematite Jasper ore
and low reactive coal such as Jhama coal was used for the production of ferrosilicon.

EXAMPLE:
A charge mix was prepared by blending together with the following materials:
62.5% parts by weight of Banded Hematite Jasper (BHJ) iron ore containing 60% Fe2O3 and
35% SiO2 sizing to substantially 15-20 mm size, 37.5% parts by weight of low reactive coal
such as Jhama Coal containing 57.96% fixed carbon, 9.27% volatiles, 25.05% ash and 7.72%
moisture sizing to substantially 20-25 mm size. The above materials were mixed and fed to a
500 kVA three phase sub-merged arc furnace. The power for the furnace was delivered
through vertically disposed, three 8 inch (200 mm) diameter graphite electrodes which were
embedded in the charge so as to provide a submerged arc reaction zone. Table 1 presents the
detailed analysis of the ferrosilicon produced. The presented data clearly indicate that 31 to
35% Si grade can be achieved by this charge mix.

EXAMPLE 2
A charge mix was prepared by blending together the following materials:
36.14 % by weight of Banded Hematite Jasper (BHJ) iron ore containing 60% Fe2O3 and
35% SiO2 sizing to substantially 15-20 mm size, 22.89% by weight of quartize containing
97.99% SiO2 sizing to substantially 12-15 mm size, 40.96% parts by weight of low reactive
coal such as Jhama Coal containing 57.96% fixed carbon, 9.27% volatiles, 25.05% ash and
7.72% moisture sizing to substantially 20-25 mm size.

The above materials were mixed and fed to a 500 kVA three phase sub-merged arc furnace.
The power for the furnace was delivered through vertically disposed, three 8 inch (200 mm)
diameter graphite electrodes which were embedded in the charge so as to provide a
submerged arc reaction zone. After reduction of above charge mix in the submerged arc
furnace and produced an iron-silicon alloy containing about 38-42% silicon. Table 2 presents
the detailed analysis of the ferrosilicon produced. The presented data clearly indicate that 38
to 42% Si grade can be achieved by this charge mix.

EXAMPLE 3
A charge mix was prepared by blending together the following materials:
28.85% by weight of Banded Hematite Jasper (BHJ) iron ore containing 60 % Fe2O3 and
35% SiO2 sizing to substantially 15-20 mm size, 27.88% by weight of quartzite containing
97.99% SiO2 sizing to substantially 12-15 mm size, 33.65% parts by weight of Jhama coal
containing 57.96% fixed carbon, 9.27% volatiles, 25.05% ash and 7.72% moisture sizing to
substantially 20-25 mm size, 9.62% parts by weight of petroleum coke containing 90% fixed
carbon, low amount of ash to substantially 10-30 mm size.
The above materials were mixed and fed to a 500 kVA three phase sub-merged arc furnace.
The power for the furnace was delivered through vertically disposed, three 8 inch (200 mm)
diameter graphite electrodes which were embedded in the charge so as to provide a
submerged arc reaction zone.

After reduction of above charge mix in the submerged arc furnace and produced an iron-
silicon alloy containing about 39% silicon. Table 3 presents the detailed analysis of the
ferrosilicon produced. The presented data clearly indicate that 34 to 39% Si grade can be
achieved by this charge mix.

EXAMPLE 4
A charge mix was prepared by blending together the following materials:
31.25 % by weight of Banded Hematite Jasper (BHJ) iron ore containing 60 % Fe2O3 and
35% SiO2 sizing to substantially 15-20mm size, 30.21% by weight of quartzite containing
97.99% SiO2 sizing to substantially 12-15 mm size, 38.54% parts by weight of petroleum
coke containing 90 % fixed carbon, low amount of ash to substantially 10-30 mm size.
The above materials were mixed and fed to a 500 kVA three phase sub-merged arc furnace.
The power for the furnace was delivered through vertically disposed, three 8 inch (200 mm)
diameter graphite electrodes which were embedded in the charge so as to provide a
submerged arc reaction zone. After reduction of above charge mix in the submerged arc
furnace and produced an iron-silicon alloy containing about 45% silicon. Table 4 presents the
detailed analysis of the ferrosilicon produced. The presented data clearly indicate that 32 to
45% Si grade can be achieved by this charge mix.


The major advantages of the present invention are:
1. The process utilizes low grade, highly siliceous iron ore
2. The process requires less amount of high grade quartzite
3. Less expensive Jhama coal has been utilized as a reductant.
4. The process envisage alternative source of raw materials for ferrosilicon production.
5. The process does not require any agglomeration process. Therefore no binder as well
as curing is required.
6. The process does not involve any pre-reduction steps.

WE CLAIM:
1. A process for the production of ferrosilicon from lean ore comprising the steps of:
grinding the lean ores, low reactive coal, quartzite and pet coke to the size ranging
between 10-30 mm;
mixing the said ores, lower active coal quartzite and pet coke in a ratio ranging between
1:1.13:0.63:0 to 1:0:0.97:1.23;
introducing the said mixture in a submerged arc furnace having the temperature in the
range of 1700 to 1900°C for a period of 3-4 hrs;
tapping the materials into the metal moulds.
2. The process as claimed in claim 1, wherein the said lean iron ore is Banded Hematite
Jasper (BHJ) having a composition in range of: 52 to 60% Fe2O3, 34 to 48% SiO2, 1 to
2% A12O3
3. The process as claimed in claim 1, wherein the said low reactive coal is selected from
Jhama coal and like having a composition in the range of 57 to 79% Fixed Carbon, 12 to
25% Ash, 5 to 10% Volatile Matter.
4. The process as claimed in claim 1, wherein the quartzite is having the composition: 97.5
to 98.5% SiO2, 0.2 to 0.3% Fe2O3, 0.2 to 0.4% Al2O3.

5. The process as claimed in claim 1, wherein the said pet coke is having the composition:
91 to 93% Fixed Carbon, 7 to 8% Volatile Matter, 1-2% Ash.
6. A process for the production of ferrosilicon from Banded Hematite Jasper substantially as
herein described with respect to the examples accompanying this specification.