FIELD OF INVENTION
The present invention relates to a novel apparatus for producing Hot briquetted /Direct
reduced iron by modification of design of unviable Mini blast furnace in the capacity range
of 50 TPD to 500 TPD. More particularly the apparatus as disclosed in the present
invention does not require natural gas as a reducing agent for production of Hot briquetted /
Direct reduced iron.
BACKGROUND OF THE INVENTION
In the present scenario, Mini blast furnaces in the size range 50 TPD to 500 TPD are
getting obsolete and unviable due to high cost of raw material Iron ore and specially Coke.
Furnaces are operating with high Coke rate above 750 Kg. to 1000 Kg. depending upon
quality of Coke as against International average of 400 - 450 Kg.
More than 100 units have thus become un-operational and are not working since past years
resulting in loss of employment and non performing asset of bank and gross loss to the
nation as a whole. Total blockade of fund ranges in Crores. Unutilised capacity is more
than 5 million Ton in context to Indian scenario. Thus there exists a huge problem in the art
to device suitable technology to produce hot briquetted iron and/or direct reduced iron
through an alternative means by converting existing unviable miniblast furnaces though
addition of balancing units.
In the present scenario Hot briquetted iron (HBI) is produced all over the world using
natural gas. Consumption of Natural gas varies from 260 to 270 Nm3/Ton of HBI
production. The technology is clean, pollution free and environment friendly. Metallization
of production varies from 88 -92 % depending upon quality and characteristic of Iron ore,
quality of Natural Gas used, total residence time in the retort. But such technology cannot
be efficiently used due to non-availability of natural gas more particularly in countries like
India. Further cost of natural gas is also high. Production is approximately, 6 million ton
per annum. Thus there exists a long felt need in the technology to produce an alternative
means for producing HBI without the use of nitrogen as natural gas.

Direct reduced iron (DRI) is produced using non-coking coal gas as reducer and heat
producer. Size of iron ore used is normally, 5 mm to 18 mm. Coal consumption varies from
1.3 to 1.8 ton per ton of DRI. Quality of DRI is not very good, un-like HBI quality and
degree of metallization often varies from 80 -85%. More than 300 plants and are now in
operation in the Indian scenario, capacity of Kiln ranging from 50 TPD to 500 TPD.
Production is approximately, 17 million Ton per Annum. Process is extremely polluted one
and not at all environ friendly. Hence there is a requirement to produce an eco friendly cost
effective means for producing DRI without extensively using only coal gas as reducer and
heat producer.
Declining supply of quality coking coal and escalating prices of coke have led iron and
steel manufacturers to seek other carbon-based products to reduce the consumption of the
more expensive coke. The global production of DRI is increasing over the years due to
increased production from Middle east and India and it will go up in future also due to new
production facilities coming up in Middle East based on gas and in India, mainly through
coal gasification route. But such procedures are not at all eco friendly looking at today's
standards of environmental norms.
Thus there is a long felt need in the technology for a solution to produce hot briquetted iron
and/or direct reduced iron through an alternative means which does away exclusive use of
coal gas in the said process and is suitable for use in small and medium scale producers
with mini blast furnace structures.
The present invention meets the above-mentioned needs which are not disclosed in the
prior art by providing a novel method and apparatus for producing hot briquetted /direct
reduced iron.
OBJECT OF THE INVENTION
The principal object of the present invention is to provide an apparatus for production of
hot briquetted/ direct reduced iron in a Vertical shaft furnace by modification of design of a

Mini blast furnace through a hybrid process using both solid and gaseous reductant through
gasification of coal.
Another object of the present invention is to provide an apparatus for production of hot
briquetted/ direct reduced iron in a Vertical shaft furnace by modification of design of a
Mini blast furnace by a hybrid process which is particularly suited for small scale
production of HBI/ DRI.
Another object of the present invention is to provide an apparatus for production of hot
briquetted/ direct reduced iron in a Vertical shaft furnace by modification of design of a
Mini blast furnace by a hybrid process, which does not require natural gas as reductant.
Another object of the present invention is to provide an apparatus for production of hot
briquetted/ direct reduced iron, which does not exclusively use only non-coking coal as
reducer and heat producer.
Another object of the present invention is to provide an apparatus for production of hot
briquetted/ direct reduced iron which uses high ash non coking coal which is abundantly
available in the market for Gasification of coal.
Another object of the present invention is to provide an apparatus for production of hot
briquetted/ direct reduced iron in a Vertical Shaft furnace by modification of a design of a
Mini blast furnace by a hybrid process which is more economic, cheap and at the same time
is simultaneously environment friendly.
In addition, the present invention discloses some advantageous features, still not disclosed
in prior art.
How the above objects are achieved would be clear to persons skilled in the art from the
following non-limiting description.
All through the specification including the claims, the words "furnace", "iron", "coke",
"coal", "producer gas", "ash", "direct reduced iron" (DRI) and "hot briquetted iron" (HBI)
are to be interpreted in the broadest sense of the respective terms and includes all similar

items in the field known by other terms, as may be clear to persons skilled in the art.
Restriction / limitation, if any, referred to in the specification, is solely by way of example
and understanding the present invention.
SUMMARY OF THE INVENTION
The present invention discloses an apparatus for production of hot briquetted/ direct
reduced iron in a Vertical Shaft Furnace by modification of design of a mini blast furnace
by a hybrid process using solid as well as gaseous reductant, said apparatus comprising, a
gasification plant, a vertical shaft Furnace, a dust separation and pollution control unit, a
raw material handling system and associated instrument and process controllers.
As according to the preferred embodiments of the present invention:
- said gasification plant comprises of a battery of fixed bed gasifier, raw coal
handling station, pre-gas boosting station, electrical tar precipitator, sulphur;
- carbon dioxide removal station, a moisture removal station and a gas boosting
station operatively associated with a gas pre heater;
- said vertical shaft by modification of design of mini blast furnace is operatively
associated to a top charging system, a gas injection system and a secondary cooling
system;
- said dust separation and pollution control unit comprises of a primary dust
collecting station, a secondary dust collecting station and a carbon dioxide removal
unit;
- said raw material handling system comprises of a set of ground hoppers, a screening
house, a set of day bins and a set of batching hopper;
- said instrument and process controllers comprises of temperature monitor and
control means, pressure transmitter and gauges, gas volume measurement and
control means, and a gas analyzer to analyse gas composition;

- said gasification plant comprises of a battery of fixed bed gasifiers using air and
steam as the gasifying agent; and
- said apparatus chiefly comprises a hybrid process using simultaneous solid and
gaseous reductant from coal gasification plant.
The present invention also discloses a method for production of hot briquetted /direct
reduced iron in a Vertical Shaft furnace by modification of design of Mini blast
furnace, said method comprising, keeping weighed briquette along with coke in a retort,
drying and heating said retort, subsequent charging of said retort, blowing hot air blast
through tuyeres, and blowing hot reformed producer gas with simultaneous increase in
temperature, volume and pressure to result in formation of Direct reduced iron after
predetermined period.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present invention would be better understood from the following illustrative drawings
and description:
Figure 1 is a process flow chart of the apparatus for production of hot briquetted/ direct
reduced iron as disclosed in the present invention
DETAILED DESCRIPTION OF THE INVENTION
As stated herein before the main object of the present invention is to provide a novel
apparatus and method for production of hot briquetted /direct reduced iron The nature of
the invention and the manner in which it is to be performed would be clear from the
following detailed non limiting description of the invention.

The above process is differed from Conventional Gas based and Coal based Process in
many ways and suitable for small and medium scale DRI producer. The process is Eco and
Environment friendly.
The process uses iron-ore fines (in the form of Sinter/Briquette /pellets) or calibrated lump
ore (+10, -18mm). Fe content will be minimum 60%. Reductant will be reformed producer
gas as well as solid fuel in the form of coke or high strength bituminous coal. Coal/ coke
size is (+15 mm, -25 mm).
The apparatus as disclosed in the present invention is stated herein after by a detailed non-
limiting description according to the process low diagram as shown in Figure 1.
Hard, Bituminous, Non-coking, origin will be used in the gasifier to generate desired
quality gas required for injection of hot gas through Tuyeres. All type of Coal Grade from
A to F can be used in the gasifier but for economic purpose only Grade C to F will be used.
NCV (Kcal/ kg):- 4200 - 5200
Ash + Moisture :- 28 - 45% (max)
Volatile matter :- 25 - 30% (min.)
Fixed Carbon :- 32 - 42 % (min.)
The producer gas composition used in the method for auxiliary fuel injection as disclosed
in the present invention is as follows:
CO -25 to 28%
H2 - 13 to 15%
CH4 - < 2%
CO2 - 4 to 5%
CnHm -≤ 5%
O2 - ≤ 0.5%
N2 - Balance
Moisture - 2 to 3% max.
(Dust and Tar content < 50 mg/ NM3)

Gas will be free from Tar, Sulphur, Suspended Particle, and Moisture through electric tar
precipitation and moisture separator.
Gas Quality.
CO + H2/(CO2+Moisture) ≥ 6
CO+H2/CO2 ≥ 8
a) Coal Gasification plant will not require any Oxygen separation unit, which will save
cost on project.
b) Gas Pressure will be boosted up to 1.5 kg/cm2 before sending to specially
developed gas pre - heater (Intermittent type) to a temperature of 1050°C - 1100 °C.
c) Hot Gas will be blown to the retort through Copper cooled tuyeres above 1050°C.
d) Top gas will be collected, cleaned in cyclone separator and Bag filter to have dust
content less than 50 mg/NM3. Top Gas will be scrubbed for CO2 removal
e) Top gas will be used to reheat Gas pre-heater and excess gas will be send to
Sintering/ Briquetting Plant as also used in Gas mixing/ cooling purpose.
f) There will be more than two gas pre - heaters in the system ,which will be operated
intermittently on gas and on reheating purpose.
g) The plant will have on line gas analyzer at the gas inlet level after booster and outlet
level after Bag filtration as well as after CO2 scrubbing unit to determine
continuously/ periodically quality of input and output gas in the process.
h) Oxygen separation unit is disposed off with the intention of bringing 48 - 50% N2
in the gas, which will be bringing enormous sensible heat in the system and
consumption of coal throughput per hour in the gasifier is reduced along with flow
of reducing gas in the retort.
Envisaged Techno-economics of the Process:
I) SP. consumption of Iron ore - 1400kg/ton DRI
II) SP. consumption of coke/ coal - 100 /150 kg/ton DRI
III) SP. consumption of PG Gas - 2400 NM3/ ton DRI
IV) Degree of metallization - 88 - 90%
V) Residual time in the retort - 10 - 12 hrs depending upon degree of metallization.
The entire apparatus consists of three units.
a) Sintering and Briquetting Plant of Matching capacity.
b) Coal Gasification Plant of matching capacity.
c) Reactor (where iron ore will be reduced) along with cooler etc. if cold briquette
/DRI to be produced.
d)
Minimum plant capacity is 50 TPD and maximum plant capacity is pegged at 500 TPD
from single module. The plant will not require any air separation (oxygen) plant for the
process.

A step by step description of the method taking place in the apparatus disclosed in the
present invention is detailed herein after:
Sintering /Briquetting
i) Iron ore fines, Mill Scale, Process flue dust, Returned fines, water (4-5%)to be
mixed in proper proportion with Coke breeze to prepare green mix in a barrel
mixer.
ii) Green mix will be kept in a receiving hopper along with bedding material in a
separate hopper.
iii) Bedding material will be discharged first on pallet Grate and then green mix. Mix
is then levelled.
iv) Pallet Car is brought under ignition hood, bed is ignited and suction is created
underneath.
v) Sintering process goes on and completed within 15-18 minutes, depending upon
bed height.

vi) Hot Sinter is delivered on crushing deck. Sinter is crushed and cooled in a Sinter
Cooler.
vii) Sinter size + 6 mm to (-)20 mm is taken to the DRI bin and( -)6mm sent to
returned fines bin. Some + 20 to - 25 mm Size is taken as bedding material.
viii) For Briquette making, a special briquetting Process will be used to produce green
briquette using bentonite and molasses as binder, dried and then fired on Sintering
Grate
DRI Making:
i) Sinter / Briquette will be stored in separate storage bin along with Coke (15 mm, -
25 mm) in separate bins.
ii) Weighed Sinter, Flux and Coke will be charged through top of VSK via Skip and
put into the Retort.
iii) Retort is kept heated by Producer gas to a temp. of 500° - 600°C
iv) At first, Retort will be charged with gravel / quartz up to the top leaving 1.5 metre
in the stack zone.
v) Sinter, and Coke is then charged on gradually and hot Producer Gas is blown at a
temp. of 600°C Process begins .
vi) Bottom discharge unit is operated at a Pre determined rate to discharge out sand
and gravel from the Retort and Retort is charged by Sinter, Briquette Coke and
process continues.
vii) Temp. of PG Gas is increased gradually to reach 1050°C by the time charge is
reaching the tuyere level.
viii) After about 6 -8 hours DRI would come out from the bottom and cooled in a
Cooler or sent to Steel melting furnace directly. Degree of Metallization will be 80
- 85%. For higher Metallization (86 - 90%), total residence time will be 8 - 10 hrs.
ix) Temperature inside Retort will be maintained strictly within 200°C - 950°C. Temp,
Gas composition will be measured and controlled through instrumentation attached
to the VSK.
x) When Top gas generation is sufficient as detected from the open bleeder of uptake,
Bleeders are closed and Gas is drawn into GCP for using Gas heating in process gas
heaters. Producer gas supply is gradually Cutoff to reduce gas consumption.

Chemical Reaction in the Process and heat balance:-
Entire Reduction Process takes place in zone wise from Upper stack to the Lower stack.
i) At the top of the shaft, where temperature is around 200°C, moisture and combined
water will remove.
ii) In temperature region 200°C - 800°C, Iron ore will be reduced indirectly by Carbon-
monoxide and Hydrogen.

In the upper part H2 reduction will play a crucial Part because of faster
Penetration of Hydrogen atom through the grain boundary, while in the lower half
CO will take important role.
iii) In high temperature zone (800°C - 900°C), just above auxiliary tuyere level, Carbon
of Coke will take part in reduction of oxide (FeO) directly as well as Carbon will
react with Carbon-dioxide of Producer Gas to form CO. Steam will also react with
Carbon in same fashion. All the reactions are endothermic, and demand heat from
the system.

To maintain the heat demand, Producer Gas will be heated at 1000°C - 1050°C to bring
sensible heat in the retort.
The principle parameters affecting metallization are: -
i) Utilization of reducing gasses
ii) Quality of PG gas (Coal gas)
iii) Flow rate of PG gas

iv) CO2 content of PG gas
v) H2/CO ratio of PG gas
vi) Temperature of PG gas at tuyere level
Heat Balance of the Entire Process can be written as : -

The apparatus for production of hot briquetted/ direct reduced iron in a Vertical Shaft
furnace by modification of design of a mini blast furnace by a hybrid process, using solid
as well as gaseous reductant, as disclosed in the present invention has been described in
context to associated Figure 1 in further details as follows:
1.0 Gasification plant
1.1 Battery of fixed bed gasifier
Gasification plant will be battery of fixed bed gasifiers of 3.2M - 3.6M dia extended
shaft type. Wherein, Indian non-coking coal will be gasified using Air and steam. No
oxygen plant is required.
High Ash non-coking coal up to 45 % - 50 % (Ash + Moist) will be used for
gasification purpose.
1.2 Raw coal handling station
A complete automated raw coal handling plant with moisture reduction unit using hot
flue gas.
1.3 Pre- Gas Boosting Station

A pre- Gas Boosting Station to boost up pressure of raw coal gas from 100-150mmwc
to 800 - 1200mmwc before sending to electric Tar Precipitator.
1.4 Electrical Tar Precipitator
An electrical Tar precipitation unit of matching capacity to separate Tar from the raw
producer gas generated in the gasifier.
1.5 Sulphur and Carbon Dioxide removal station
A sulphur and carbon dioxide reduction unit to remove sulphur and carbon dioxide of
gas coming out from electric Tar precipitator.
1.6 Moisture removal station
A moisture separator unit to remove moisture below 5% from cleaned producer gas
coming out from sulphur and CO2 removal unit.
1.7 Gas boosting station
A set of booster pumps to boost up gas press, from 70 - 80 mm wc to 0.8 to 1.5
Kg./Cm2.
1.8 Gas Pre-Heater Station
A set of gas pre- heaters after booster pumps to increase gas temperature from 150°C
- 160°C to 1000°C - 1050°C before supply to vertical shaft furnace through gas bustle
and copper tuyeres. Gas pre heaters will be lined with refractory lining. Operation
will be intermittent or continuous one. Modification in design of Mini blast furnace
stove is done to make Gas pre-heaters.
2.0 Vertical shaft ( involves modification in design of MBF)
Vertical Shaft furnace will be made by modification of design of existing unviable
blast furnace plant
Vertical shaft furnace will have the following parts.
2.1.1 Main shell structure with refractory lining inside and proper batter profile of existing
MBF will be used.
2.1.2 Blast furnace bosh and hearth will be modified to form a conical vertical structure
for cooling and discharge of HBI / DRI from the unit.

2.1.3 Skull breaking units and pushers to be effectively installed to push the material
from
belly to the coolers.
2.1.4 Existing uptake will be utilised to take out spent gas from the vertical shaft furnace.
2.2 TOP Charging system
Existing two bell Top-charging system will be utilised to charge raw material (iron
ore, Sinter, Pellets, Coal/ Coke, Lime stone, Dolomite) from top via a skip charging
system operated from ground control room.
2.3 Gas Injection System
Existing bustle pipe with modification in blowpipes, bends and tuyere systems will
be utilised to blow hot clean producer gas in the VSK.
2.4 Secondary Cooling System
A small rotary cooler unit attached to the conical bottom cooler for further cooling
of DRI.
3.0 Dust Separation and Pollution Control Unit (Dry Type)
Existing Gas cleaning unit comprising of the following will be utilised .
3.1 Primary Dust Collecting Station
A suitable size Primary Dust Catcher to separate large size particles from the spent gas
coming from VSK.
3.2 Secondary Gas Collecting Station
3.2.1 A battery of Cyclone separators to separate Dust content further along with all
valves.
3.2.2 A battery of bag filtration Plant along with all valves and pipe line for final cleaning
of Dust from the Gas. Final Dust Content will be below 50 ppm.
3.3 Carbon-di-oxide removal unit
A separation Carbon dioxide removal unit will be utilised to separate Carbon-di-
oxide from clean spent gas to improve Calorific Value as well as reduction power
of Gas.

4.0 Raw - Material Handling System
Existing Raw material handling system of the plant will be utilised comprising of :-
4.1 A set of Ground - Hoppers to stock Raw-material - Iron Ore, Briquette, Sinter,
Coke/ Coal, Fluxes prior to Screening.
4.2 A Screening House to separate fines and Dust from the raw material coming from
Ground Hopper through Conveyor Belt.
4.3 A set of Day-bins (6 or 7) to stock screened raw material from charging to VSK.
4.4 A set of Batching Hopper (on load cell) underneath each day-bin to weigh Raw
material accurately before charging into the VSK.
5.0 Instrumentation and Process Control
Existing instrumentation and process control system will be modified to contain,
5.1 Temperature monitor and Control attached to Gasifier, VSK, Gas pre-heater, Spent
Gas Line (Uptake, Dust Catcher, Cyclone, Bag filters) to control closely process
temperature.
5.2 Pressure Transmitter and Gauges to monitor Gas Pressure, Air Pressure, Steam
Pressure in gasifier, VSK, Gas Pre-heater, Gas - bustle, Bag Filters Line.
5.3 Gas Volume measurements and control from Gas received from gasification Units,
Gas Boosters Pumps To Gas Pre-heaters, Pre heaters to VSK and finally Spent Gas
Volume.
5.4 Gas Analyzer
New Gas analyser unit to be installed for,
5.4.1 To analyze Gas composition as regards H2, CO, CO2, CH4 and other Hydro Carbon
in Fresh Clean Gas coming out from Gasifier Units after Sulphur, CO2 and Tar
removal.
5.4.2 To analyze Gas Composition of Spent Gas after Bag Filtration Unit.
5.4.3 To analyze Gas Composition of cleaned Spent Gas after CO2 removal in the return
line.
The present invention has been described with reference to some examples and preferred
embodiments, purely for the sake of understanding and not by way of any limitation and
the present invention includes all legitimate developments within the scope of what has
been described hereinbefore and claimed in the appended claims.

I claim:
1. An apparatus for production of hot briquetted/ direct reduced iron in a Vertical shaft
furnace by modification of design of a Mini blast furnace by a hybrid process using
solid as well as gaseous reductant, said apparatus comprising, a gasification plant, a
vertical shaft, a dust separation and pollution control unit, a raw material handling
system and associated instrument and process controllers.
2. The apparatus for production of hot briquetted/ direct reduced iron as claimed in
claim 1, wherein the said gasification plant comprises of a battery of fixed bed
gasifier, raw coal handling station, pre-gas boosting station, electrical tar
precipitator, sulphur and carbon dioxide removal station, a moisture removal station
and a gas boosting station operatively associated with a gas pre heater.
3. The apparatus for production of hot briquetted/ direct reduced iron as claimed in
claims 1 and 2, wherein said vertical shaft is operatively associated to a top
charging system, a gas injection system and a secondary cooling system.
4. The apparatus for production of hot briquetted/ direct reduced iron as claimed in
claim 1, wherein said dust separation and pollution control unit comprises of a
primary dust collecting station, a secondary dust collecting station and a carbon
dioxide removal unit.
5. The apparatus for production of hot briquetted/ direct reduced iron as claimed in
claim 1, wherein said raw material handling system comprises of a set of ground
hoppers, a screening house, a set of day bins and a set of batching hopper.
6. The apparatus for production of hot briquetted/ direct reduced iron as claimed in
claim 1, wherein said instrument and process controllers comprises of temperature
monitor and control means, pressure transmitter and gauges, gas volume
measurement and control means, and a gas analyzer to analyse gas composition.

7. The apparatus for production of hot briquetted/ direct reduced iron as claimed in
claim 1 and claim 2, wherein said gasification plant comprises of a battery of fixed
bed gasifiers using air and steam as the gasifying agent.
8. The apparatus for production of hot briquettedV direct reduced iron as claimed in
any preceding claims, wherein said apparatus chiefly comprises a hybrid process
using simultaneous solid and gaseous reductant from coal gasification plant.
9. An apparatus for reformed coal gas injection in a vertical shaft furnace for reduction
of iron substantially as described in the description and illustrated in drawings.
10. A method for production of hot briquetted direct reduced iron in a vertical shaft
furnace, said method comprising, keeping weighed briquette along with coke in a
retort, drying and heating said retort, subsequent charging of said retort, blowing
hot air blast through tuyeres, and blowing hot reformed producer gas with
simultaneous increase in temperature, volume and pressure to result in formation of
direct reduced iron after predetermined period.

An apparatus for production of hot briquetted/ direct reduced iron in a Vertical shaft
furnace by modification of design of a Mini blast furnace by a hybrid process using solid
as well as gaseous reductant, said apparatus comprising, a gasification plant, a vertical
shaft, a dust separation and pollution control unit, a raw material handling system and
associated instrument and process controllers.