TITLE: A process for production of ferrosilicon from Banded Hematite Quartzite.
FIELD OF INVENTION:
This invention relates to a process for production of ferrosilicon from Banded
Hematite Quartzite.
BACKGROUND OF THE INVENTION:
Ferrosilicon is used as an alloying element and deoxidizer in iron and steel
industries. The addition of ferrosilicon into the steel and cast iron would improve the
strength, hardness, and corrosion resistance of steel product directly. In the Pidgeon
process for production of magnesium from dolomite ferrosilicon is used [M. Halmann,
A. Frei, and A. Steinfeld, Ind. Eng. Chem. Res. 2008, 47, 2146 - 21542]. Ferrosilicon
is used as inoculants which accelerate graphitization during the production of cast
iron. In arc welding, ferrosilicon is used in electrode coatings.
Because the world-wide availability of high grade raw materials is diminishing, the
need to utilize alternative source is very important for the sustainable development.
Generally, ferrosilicon is produced in submerged electric arc furnaces by the
carbothermic smelting reduction of the quartzite. Constantly good quality quartzite is
required to obtain consistent quality of ferrosilicon.
The existing ore 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
and reductant. Normally, silica is the major impurity present in the Banded Hematite
Quartzite (BHQ) sample. To recover iron value, it has to be

crushed and subsequently beneficiated. These ores typically consist of bands of
iron-bearing hematite intergrowth with quartz. Therefore, beneficiation of Banded
Hematite Quartzite (BHQ) results in low yield and process would not be economically
viable. Alternative way may be to use it a feed material for ferrosilicon production as
it has contain very high level of silica.
Generally, submerged arc furnace is used for production of standard grade
ferrosilicon using quartzite, petroleum coke and silicon steel filings or pure iron
[Chinese patent No. CN1103896-A]. Reference may be made to Patent No:
SU550428-A wherein Kanaev et al used turnings or metal splash of 3 mm are used,
all of which are suitable for compacting with sand and coal or coke to produce
ferroalloys. Reference may be made to Patent No: US 4526612 wherein an energy-
rich plasma gas reaction chamber has been introduced 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 3704114] 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 content.
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 in the 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 above known processes had the following draw backs:
i) Required high quality raw materials such as quartzite, petroleum coke, silicon
steel filings, pure iron, and turnings, which increases the cost of production of
ferrosilicon/ton effectively,
ii) In some process, grinding of raw materials is required for agglomeration.
Therefore, binders are also very important which makes the process expensive,
iii) To obtain sufficient cold handling strength, sometimes curing is also required
which add to the energy consumption.
OBJECTS OF THE INVENTION:
An object of the present invention is to propose a process for the production of
ferrosilicon from Banded Hematite quartzite (BHQ);
Another object of the present invention is to utilize low reactive coals such as Jhama
coal as an alternative source of reducing agent for the production of ferrosilicon;
Further object of the present invention is to propose a suitable process to improve
the grade of ferrosilicon by using combination of the low reactive coal such as Jhama
coal and pet coke.

BRIEF DESCRIPTION OF THE INVENTION:
According to this invention there is provided a process for the production of
ferrosilicon from Banded Hematite Quartzite comprising the step of:
subjecting banded hematite (BHQ), low reactive coal, quartzite and pet coke to the
step of crushing;
mixing banded hematite quartzite (BHQ), low reactive coal, quartzite and pet coke in
the ratio ranging between 1:1:0.25:0 to 1:0:1.33:1.53;
introducing the said mixture of raw materials in submerged arc furnace having a
temperature range from 1700 to 1900°C;
tapping the materials into the moulds.
DETAILED DESCRIPTION OF THE PRESENT INVENTION:
The process of the present invention 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 material in the charge was
variable and dependent on the percentage of silicon desired in the iron-silicon alloy
to be produced. In order to get higher recovery of ferrosilicon the inventors have
been tried different proportion of raw materials. The size of the iron-bearing Banded
Hematite Quartzite (BHQ) material was about 15 to 20 mm. The size of the quartzite
material is about 12 to 15 mm and the size of the Jhama coal is about 20 to 25 mm.
The fixed carbon content in the charge was also a variable and varied between 57 to
79% depending on the desired ferrosilicon alloy required to produce. For example,
the fixed carbon content 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 Quartzite (BHQ) according to the reaction

SiO2+2C→ Si + 2CO----(1)
Fe2O3 + 3C → 2Fe + 3CO-----(2)
For the production of 60% ferrosilicon and a maximum of about 120% of the
stoichiometric amount necessary for the reduction of all the silica. The energy
consumption for the production of 60% Fe-Si production in submerged arc furnace
using above charge mix requires around 10800 kWh/ton of ferrosilicon. In addition, a
saving can be realized from a reduction in the electrode consumption rate is about
100 kg per ton of ferrosilicon.
Thus, the present invention provides a process for the production of ferrosilicon from
Banded Hematite Quartzite which comprises:
i) sizing of Banded Hematite quartzite (BHQ), low reactive coal such,
quartzite and pet coke in the ratio ranging between 10-30 mm in size,
ii) mixing Banded Hematite quartzite (BHQ), low reactive coal, quartzite
and pet coke in the ratio ranging between 1:1:0.25:0 to 1:0:1.33:153,
iii) charging the above mixture of raw materials in submerged arc and
maintaining temperature in the range of 1700 to 1900°C for a period of
3-4 hrs,
iv) tapping the materials into the metal mould by known method.
In an embodiment of the present invention the used Banded Hematite Quartzite may
have the following compositional range: 47 to 52% Fe2O3, 46 to 48% SiO2, and 1 to
2% Al2O3.
In another embodiment of the present invention the low reactive coal may be
selected from or like low reactive coal and may have the following compositional
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 compositional range : 97.5 to 98.5%SiO2, 0.2 to 0.3% Fe2O3, and 0.2 to
0.4% Al2O3.
In yet another embodiment of the present invention the used pet coke may have the
following compositional range: 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 relates to the utilization of low grade iron ore and low reactive
coal for the production of ferrosilicon. The low reactive coal such as Jhama coal
which are currently not being used for any of the production processes in iron and
steel sector or alloy steelmaking and thereby the invention is novel from the view
point of environmental protection and waste resource utilization.
EXAMPLES:
The following examples are given by way of illustration and should not be construed
to limit the scope of invention.
EXAMPLE 1
The charge material containing Banded Hematite quartzite (BHQ), Jhama coal,
Quartzite and pet coke in the ratio 1: 1.4:0.95:0 was mixed uniformly. Then it was
charged in the 500 kVA submerged arc furnace. Table 1 presents the detailed
analysis of the ferrosilicon produced. The presented data clearly indicate that 43 to
48% Si grade can be achieved by this charge mix.


The charge material containing Banded Hematite Quartzite (BHQ), Jhama coal,
Quartzite and pet coke in the ratio 1:0.5:133:1 was mixed uniformly. Then it was
charged in the 500 kVA submerged arc furnace. Table 2 presents the detailed
analysis of the ferrosilicon produced. The presented data clearly indicate that 55 to
63% Si grade can be achieved by this charge mix.

The charge material containing Banded Hematite Quartzite (BHQ), Jhama coal,
Quartzite and pet coke in the ratio 1: 0:1.33:1.4 was mixed uniformly. Then it was
charged in the 500 kVA submerged arc furnace. Table 3 presents the detailed
analysis of the ferrosilicon produced. The presented data clearly indicate that 59 to
65% Si grade can be achieved by this charge mix.

WE CLAIM:
1. A process for the production of ferrosilicon from Banded Hematite Quartzite
comprising the step of:
subjecting banded hematite (BHQ), low reactive coal, quartzite and pet coke to the
step of crushing;
mixing banded hematite quartzite (BHQ), low reactive coal, quartzite and pet coke in
the ratio ranging between 1:1:0.25:0 to 1:0:1.33:1.53;
introducing the said mixture of raw materials in submerged arc furnace having a
temperature range from 1700 to 1900°C;
tapping the materials into the moulds.
2. The process as claimed in claim 1, wherein the size of each of the raw materials is
in the range between 10-30mm.
3. The process as claimed in claim 1, wherein the mixture of raw materials is heated
in the submerged arc furnace for a period of 3 to 4 hrs.
4. The process as claimed in claim 1 wherein the used Banded Hematite Quartzite
have the following compositional range:

5. The process as claimed in claims 1-2 wherein the low reactive coal is selected
from or like low reactive coal and may have the following compositional range:


6. The process as claimed in claims 1-3 wherein the quartzite used have the
following compositional range:

7. The process as claimed in claims 1-4 wherein used pet coke have the following
compositional range: