FORM 2
THE PATENT ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
(In respect of Provisional Application No. 655/MUM/2011 dated 9th March 2011)
TITLE OF THE INVENTION
MICROWAVE ASSISTED REDUCTION OF IRON ORE FINES TO MANUFACTURE SPONGE IRON
APPLICANT
Name PRADEEP METALS LTD.
(A Company Incorporated under the Companies Act, 1956)
Nationality Indian
Address R - 205, TTC Industrial Area,
M.I.D.C., Rabale,
Navi Mumbai-400 701
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The invention relates to production of sponge iron by a method of rapid reduction of iron ore.
The invention particularly relates to production of sponge iron from the otherwise waste and polluting iron fines.
The invention more particularly relates to production of sponge iron from iron fines by a method of electromagnetic radiation of optimum intensity and eliminating the use of any carbon containing material in the raw mix that is to be treated.
The iron ore fines used in this invention are available as mining waste from mines and have not been used in the conventional sponge iron making process thereby making the invented process cost effective and environment friendly.
The invention not only enables an affordable, safe and efficient method of production of sponge iron from iron fines, but also an eco-friendly one by eliminating the discharge of green-house gases in the process.
DESCRIPTION OF RELATED ART
The process of sponge iron manufacturing involves removal of oxygen from iron ore to obtain iron in metallic form. In sponge iron the metallization expected is more than 75% and may go upto 90 % which also depends on the quality of raw ore used for the reduction. However, this percentage metallization is estimated after completing the reduction process followed by magnetically separating the non-magnetic materials. As per BSI there are 3 grades of sponge iron depending on the metallic iron percentage; Grade I (82+%), Grade II (78-82%) and Grade III (76-78%).

The current processes for manufacture of sponge iron are characterized by high energy consumption and the release of environmentally undesirable by-products including large quantities of fines and green-house gases such as Carbon monoxide and Carbon dioxide.
The conventional process employed by most of the small and medium scale sponge iron manufacturing units is reduction/metallization of iron ore with coal in the inclined rotary kiln. In this process iron ore lumps and coal lumps are passed along with additives such as dolomite or lime stone through the kiln, in a counter current direction to the flue gases such as air and oxides of carbon such as Carbon dioxide and Carbon monoxide. With increase in temperature in the kiln, carbon gasification takes place and due to close association with the iron ore, its reduction to metallic iron takes place. The volatile constituents of the coal and carbon monoxide from the bed material are burnt in the kiln, over the entire length of the kiln with a controlled amount of air, thereby providing the necessary heat required for the reduction of iron ore. The rotary kiln discharge is cooled in a rotary cooler connected to the kiln, screened and subjected to magnetic separation in order to separate sponge iron and the non-magnetic materials such as ash or unreacted coal or ore.
There are relatively new commercial processes being employed, which are known as DRI process, for making sponge iron by integrated steel plants where direct reduction of iron ore is done by a reducing gas produced from cracking of natural gas in a catalytic cracker. The reducing gas consists of a mixture of H2 and CO. However, availability of natural gas may not be sufficient in the country especially in the areas away from the coasts.
The main raw materials required in these processes are iron ore, coal and dolomite. In the iron ore, a minimum Fe content of 62-66% is essential and the size of ore needs to be maintained between 5-18 mm. Coal acts as a reducing agent and the preferred type of coal is non-coking coal due to its certain important features viz. reactivity, ash softening temperature, caking and swelling indices and sulphur content,

etc. But, in India the availability of this type of coal is very low for such specific applications. Hence, low grade coal is being used. Coal is generally beneficiated using washing plants, and then crushed to the desired size fraction. Dolomite is mainly used as a de-sulphurizing agent to prevent the pick-up of sulphur by the sponge iron from the sulphur released by the burning of coal inside the furnace. The size of dolomite used is 4-8 mm.
These processes are energy intensive, because energy is lost in heating unwanted equipment such as long rotary kiln and its kiln furniture, from where heat is lost in the atmosphere resulting in large amount of green gas emission from the process such as carbon dioxide, carbon monoxide and oxides of sulphur.
The present invention describes the use of electromagnetic radiations such as microwave for direct reduction and metallization ot iron ore fines in much shorter duration of time than is required in known conventional processes. In the invented process, enhanced reaction kinetics are observed when microwave energy is applied to iron ore under reducing atmosphere, compared to the reduction kinetics observed in the known conventional processes. While not wishing to be bound by theory, a non-thermal effect of microwave makes the ore more amenable for reduction under electromagnetic field such as microwaves. As a consequence, the invented process becomes much faster, economical and also environment friendly.
The reducing agent used in this invention is gaseous reducing agent which is a mixture of hydrogen gas and an inert gas such as nitrogen. The invented process employs a mixture of hydrogen gas and any other inert gas in such proportions so that the hydrogen percentage in the gas mixture is always below the explosive limits of hydrogen in air which is reported to be 18 % or below. The inert gas used can be helium, argon, nitrogen. In the present invention mixture of hydrogen and nitrogen used is in the percentage ratio of 5:95 to 18:82 and more preferably in the percentage ratio of 8:92 to 10:90 respectively.

The term "direct reduction" is used to describe the reduction of a metal in a metal-containing material wherein the metal-containing material remains in a solid-state throughout the reduction process.
The term "metallization" is used to describe the reduction of a metal in a positive oxidation state (higher than 0) to a metal having a zero oxidation state, for example Fe3+ to Fe°
Microwave heating, as disclosed, transmits energy into electrically non-conductive materials or small agglomerations of the metallic ore more efficiently than the conventional heating process with fossil fuels or radiation electrical heating process.
Use of microwaves is established for processing different materials including minerals and various processes have been developed for the same in the reduction of metallic compounds to metals using carbonaceous reducing agents such as coke, coal.
US 6277168 discloses a process for reduction of metallic ores to molten pig iron using coal or carbon-containing material for reduction using microwaves.
JP20090073169 discloses a process for reduction of iron oxide containing material which is carried out in two stages. In the first stage, iron ore (hematite or goethite) is reduced with reducing gas to magnetite. Then this is mixed with, carbon containing reducing agent and further heated by microwave, to convert in to metallic iron.
CN1724695 discloses a method for manufacturing low carbon sponge iron using microwave vertical furnace. The disclosed process adopts iron ore powder as raw material, common soft coal dust or anthracite dust as reducing agent to gain high quality low carbon sponge iron.
In contrast to the methods of producing sponge iron disclosed above, the process of the present invention eliminates the use of coal or other carbonaceous

materials as reducing agent in the raw mix thereby eliminating/reducing the emission of green-house gases considerably. It is clear that the abovementioned examples of prior art do not possess the novel attributes of the present invention, namely clean and direct production of sponge iron using the iron ore fines which are considered as unusable. This invention discloses a method of producing sponge iron from iron ore fines by utilizing electromagnetic energy such as microwave energy at frequency between 800 to 5000 MHz, more preferably from 890 to 2450 MHz and most preferably at 2450±50MHz as the primary energy source which generates internal heat through interactions of metallic atoms volumetrically, rapidly and selectively and is more energy efficient from any of the other metal making techniques. The advantages of the invented process include using low grade materials in the form of fines or pellets, and flexibility of the process where reduction is done using a reducing gas mixture consisting of Hydrogen and Nitrogen thereby eliminating the use of coal and generation of greenhouse gases.
The invented process can also use synthetic gas or water gases which are used in the commercial manufacturing processes as reducing gas mixtures. Generally the synthetic gas consists of 14% H2 along with 27% of CO and 5% C02. This gas mixture contains about 51% nitrogen. The composition of water gas contains about 47% H2l 8% CO and 4% C02. It also contains about 10% nitrogen and 27% Methane. Considering the amount of green gas emitted from conventional process where about 3 parts of coal is used per one part of iron ore, the green gas generated by these synthetic gases will be 70% lower than the known conventional process. Thereby making the process simple, clean, economical and versatile.
As per the technical publication by Centre for Techno-Economic Mineral Policy Options (C-TEMPO), a registered society under Ministry of Mines, Govt, of India (http://www.c-tempo.org/studies) in 2011 titled "Relevance of iron ore peptization industry in India - A Perspective"; utilization of low grade ore and fines has to play an important role. In India, partly due to the sponge iron sector; the overall percentage of lumps usage in steel making (47%) is higher than most other countries. As hard ore

reserves are depleting day by day, lump generation suitable for blast furnace operation is coming down, resulting in production of large amount of surplus fines. As fines form considerable unusable part of iron ore resources, it is necessary to develop a process for utilizing these unused resources.
Hence there is also a very important need, that these highly potential resources of iron, which are otherwise considered waste and polluting materials, also be deployed in formation of good quality iron. Some method is required whereby good quality iron can be produced by treating these iron fines and also control the discharge of greenhouse gases.
There is a clear need to overcome these existing limitations.
OBJECT OF THE INVENTION
It is an object of the invention to evolve a method of rapid reduction of iron ore resulting into formation of sponge iron, but at the same time utilizing the otherwise waste and polluting products such as iron ore fines. It is another object of the invention to reduce the release of green-house gas emissions by eliminating the use of carbonaceous material such as coal as a reducing agent in the raw mix.
It is yet another object of the invention to evolve a method of rapid reduction of iron ore resulting into the formation of sponge iron, but at the same time this method is simple, easy to operate, inexpensive, affordable, less risky in operating and extremely economical in terms of the system design and the operating process wherein both the costs and the energy consumption is reduced.

SUMMARY OF THE INVENTION
The present invention is an eco-friendly method, for manufacture of sponge iron from iron ore and its fines with drastic reduction in release of green gases with rapid and direct reduction of iron ore in the form of lumps/fines/pellets comprising of the following steps: providing the iron ore in the form of lump/fines/pellets in a ceramic container; placing the container in a microwave cavity; volumetrically heating to 900-1250°C by applying microwave energy in a reducing atmosphere comprising a mixture of hydrogen with any inert gas; soaking at 900-1250°C in a reducing atmosphere until the percentage metallization achieved is atleast 75%; removing the container out of the microwave cavity; cooling the container with the contents to obtain sponge iron in the same form as the feed.
The invented process uses iron ore rejects in the form of lumps or fines for reduction. This can be converted into pellets with or without using a binder and with or without milling. The iron ore pellets are then dried and placed in a container made of ceramics. The ceramic container is made of material transparent to microwaves such as alumina, zirconia, cordierite, mullite, quartz or using materials which act as good susceptors such as graphite, silicon carbide or mixture of transparent and susceptor material such as alumina and silicon carbide or alumina coated with graphite and capable of withstanding temperatures used for reduction, without reacting adversely with any of the constituents of the reactants or products. The ceramic container is placed in a microwave cavity, wherein a reducing gas mixture comprising an inert gas such as nitrogen, and hydrogen in desired and safe proportions is purged. Microwaves are generated using a water cooled magnetron and are introduced in the microwave cavity through a circulator and a horn. Microwaves heat and reduce the iron ore pellets placed in the microwave cavity in a selective, rapid and volumetric manner.
The viability of the invented novel process lies in the fact that iron ore is an excellent microwave absorber. This new, simplified process translates rapid and volumetric heating of iron ore in microwave field thereby producing sponge iron in a

short duration and results into higher productivity, less environmental pollution and higher energy efficiency using a simple process.
The iron ore can be used as lumps or fines. Fines with grain size of 100% passing 300 microns, preferably 100% passing 150 microns are pelletized directly. The coarse grains of the ore can be typically milled down using any industrial milling system before peptization to the desired size. By using finer grains the reduction kinetics is accelerated.
The pellets may be prepared without adding any binder, but to increase the strength, a clay based binder can be added to iron ore fines preferably less than 2% by weight. The binder used can be any economic industrial binder such as bentonite, hydrated lime, sodium silicate or molasses.
The present invention uses reduction temperature less than 1250°C preferably at about 1100°C. As per iron-hydrogen phase diagram, it is essential to maintain temperature above 912°C to maintain iron in the gamma phase (austenite phase). The upper temperature limit to maintain iron in gamma phase (austenite phase) is 1394°C.
For economics, in the present invention, reduction was attempted at 1250°C, where soaking time (i.e. holding the material at the desired temperature for completion of the desired reaction) was about 1 hour. However, for still better economics and ease, the direct reduction was done at a lower temperature i.e. 1100°C. at this temperature, the soaking time was 2 hours where higher % metallization was achieved. Depending on the commercial requirements, the process can be tuned to obtain >90% metallization by reduction of iron ore and its fines in to sponge iron.
The invented process can also use other type of commercial reducing gas mixtures such as synthetic gas or water gas in place of nitrogen-hydrogen gas mixture. Where the reducing gas mixture contains oxides of carbon such as CO, CO2, then as per iron-carbon phase diagram, above 727°C, alpha iron transforms into gamma phase

(austenite phase) and remains solid below 1149°C. Beyond this temperature gamma phase (austenite phase) transforms into liquid phase. Hence, the reduction needs to be carried out at 1100°C with reducing gases containing oxides of carbon such as CO, CO2 along with hydrogen.
The use of microwaves is known for mineral processing, but the simple design and optimum exposure of microwaves to the ore under the invented optimized process conditions makes the invented process suitable for reduction of the metal containing ore to the desired level. The complex designs, complex processes may provide better results, but simple design with huge economic benefits within reach of all is desired and the same is offered by the invented process.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1/4
The diagram is a cross section view of the microwave direct reduction furnace used in the present invention.
FIG. 2/4
The graph illustrates experimental data showing the Time - Temperature Profile i.e. heating Profile of iron ore in microwave.
FIG. 3/4
The graph represents experimental data showing the effect of temperature on percentage of metallization of iron ore when samples were heated at different temperatures from 950 to 1250°C and samples were soaked for 2 hours at each temperature.
FIG. 4/4
The graph illustrates the variation in % metallization of iron ore at different soaking times at the temperature of 1100°C.

DETAILED DESCRIPTION OF THE INVENTION
Iron containing ore such as hematite, magnetite, goethite, limonite, ilmenite or siderite can be used in the present invention. The iron containing ore can be in the form of lumps or fines. The iron containing ore is exposed to microwaves in the form of fines/ pellets/lumps in a microwave cavity. Iron ore fines such as mining waste or industrial waste containing iron ore can also be used. The ceramic sample holder is made of material that can withstand high temperatures without substantial degradation or has any adverse reaction with raw materials or products formed. In this inventive process, for rapid reduction of the iron ore, a gas mixture of hydrogen and inert gas such as nitrogen is used. In this inventive process, the raw mix is exposed to electromagnetic radiations such as microwaves. The microwave frequency can be used between 800 and 5000 MHz, preferably from 890 and 2450 MHz. The microwave frequency used in this invention is 2450±50 MHz. At this frequency, microwaves selectively heat the iron ore and the heated iron ore is reduced to metallic form in the surrounding reducing atmosphere. With microwave heating, a temperature in excess of 1000X is attained in a few minutes due to rapid interaction of microwaves with metal containing ore such as iron ore.
In an embodiment of the present invention, a microwave direct reduction furnace as shown in fig. 1/4 is used for the reduction of iron ore. According to this embodiment, a ceramic container (sagger) 9 made of suitable material is placed inside a microwave cavity 1. It is preferable to use a ceramic sagger which has a softening temperature higher than the melting point of the raw material. The said ceramic sagger 9 may be made of materials such as alumina, mullite, cordierite, quartz, graphite, silicon carbide or mixture of transparent and susceptor material such as alumina and silicon carbide or alumina coated with graphite. The said ceramic container (sagger) 9 is placed on a turn table 3 and its height is configured by placing a ceramic cylinder 4 over which a ceramic fiber board 5 is placed. The ceramic container (sagger) 9 is surrounded by hollow alumina balls 8 thermally insulating the cylinder 6 and ceramic wool 7 deposed around the outer surfaces of the ceramic container (sagger) 9 to prevent heat radiating from the

sample and achieving high energy efficiency. Iron ore fines or lumps which comprise the raw material are placed in the ceramic container (sagger) 9. The said iron ore containing sample 11 are used in the form of lumps/fines or pellets. Pellets are made from fines with or without using a binder by using suitable forming equipment such as pan granulator, where iron ore fines used are of the size of 0.5 mm, more preferably less than 0.15 mm and binding the said iron ore fines with or without adding any binder. The pellets 11 can be made with only required amount of water. Pellets 11 can also be prepared by adding around 1-2% by weight of any industrial binder such as bentonite, hydrated lime, sodium silicate or molasses along with water to achieve higher strength. It is preferable to introduce the iron ore fines in the form of pellets having diameter less than 40 mm but preferably upto 10 mm in diameter.
A lid 21 is placed on the ceramic container (sagger) 9 with a hole at the center for monitoring the temperature using an IR pyrometer 16. The reactor is closed by placing the water cooled top lid 2. The IR pyrometer 16 is aligned with the sample placed in the microwave cavity 1 over the ceramic container (sagger) 9. The microwaves are generated in a water cooled magnetron 14. These microwaves pass through a circulator 13 in the microwave cavity 1 through a horn 12. For safety of the magnetron, a dead load 15 is installed to absorb the reflected microwaves if any. The reducing gas mixture consisting of hydrogen and an inert gas is continuously flown through an inlet valve 17. The inert gas used may be argon, nitrogen, helium, more preferably nitrogen. Generally, the percentage ratio of hydrogen and inert gas such as nitrogen is 5:95 to 18:82 and more preferably in the percentage ratio of 8:92 to 10:90 respectively. The inert gas and hydrogen gas mixture acts as a reducing agent to reduce the iron ore containing sample 11 placed in the ceramic container (sagger) 9 placed in the microwave cavity 1. The exhaust gases are removed through outlet 18, cooled and then released in the atmosphere.
In a particularly advantageous embodiment of the present invention, the raw material comprising iron ore containing sample 11 is loaded into the microwave cavity 1. The interior of the microwave cavity 1 is irradiated with microwaves via circulator 13

from the magnetron 14. Microwaves irradiate the interior of the space of the microwave cavity 1. The iron ore containing sample 11 placed on the ceramic container (sagger) 9 absorbs the microwaves. The iron ore containing sample 11 is self-heated and its temperature increases. The heating and soaking of the said mixture is carried out preferably in the temperature range of 1100 to 1250°C and more preferably at 1100°C.The iron ore containing sample 11 thereby gets heated and the iron ore is reduced to form sponge iron at the invented temperature. To prevent microwaves from leaking to the outside of the furnace, the cavity is water-cooled and lid opening is sealed. The microwaves emitted from magnetron 14 entering in the microwave cavity 1 through a circulator 13 and a horn 12 are not blocked by alumina balls 6 insulating the cylinder and ceramic wool 7 because they are transparent to microwave radiations. Microwaves directly couple with the raw material placed inside the ceramic container (sagger) 9. Alumina balls 6 insulating the cylinder and ceramic wool 7 act as insulators and do not allow heat to radiate outside thereby increasing the energy efficiency of the process.
The raw material is held at fixed maximum firing temperature for different lengths of time, called "soaking times". During this duration, the temperature equilibrium takes place in the total volume of the material which facilitates completion of the desired reaction. As microwave heating is a volumetric heating process, each and every atom interacts with microwaves with a similar intensity, due to which all the atoms are almost at the same temperature and hence the soaking time during microwave processing is reduced. The time required for soaking is much less as compared to the conventional gas heating where the heat transfers depends on the conduction, convection and radiation of the sample and heating environment. Fig. 3/4 represents experimental data showing the effect of temperature on percentage of metallization of iron ore when samples were heated at different temperatures from 950 to 1250°C and samples were soaked for 2 hours at each temperature. Fig. 4/4 illustrates the variation in % metallization of iron ore at different soaking times at the temperature of 1100°C.

The exhaust gas containing H20 vapour along with unreacted inert gas and H2 gas mixture from microwave cavity 1 is released to the exterior of the furnace via outlet valve 18. The reaction of the raw material is art endothermic reaction, and a temperature in the range of 900 to 1250°C is required in order to produce sponge iron. To constantly maintain this temperature, according to the present invention, iron ore can be reduced by microwave heating to obtain sponge iron in presence of H2 and inert gas(8:92) without using carbon containing material used in the conventional process, thereby eliminating or reducing considerably emission of green-house gases making the present invention more environment friendly and contributing greatly to improving energy efficiency and reducing equipment size in the sponge iron-making process.
Reduction reactions taking place in the Microwave direct reduction furnace by using hydrogen gas (H2) as a reducing agent occurs in the following steps:-
1. 3Fe203 + H2 2Fe304 + H20(g) ∆H = -1.0kJ/MolFe
2. Fe304 + H2 3FeO + H20(g) ∆H = +24.9 kj/Mol Fe
3. FeO + H2 Fe + H20(g, ∆H = +25.4 kj/Mol Fe
4. Fe304 +4 H2 3Fe + 4H20(g) ∆H = +50.4 kj/Mol Fe
5. Fe203 + 3H2 2Fe + 3H20(g) ∆H = +49.4 kj/Mol Fe
The invented process can be adopted where the reducing gas mixture containing nitrogen and hydrogen is replaced by synthetic gas or water gas on a commercial scale for better economics. As these commercial gas mixtures contain less amount of oxides of carbon, the total green-house gas generated by the invented process even by using commercial gas mixtures will be about 70% lower than the conventional sponge iron manufacturing process where 1 part of iron ore requires 3 parts of coal. Reduction reactions taking place in the Microwave direct reduction furnace by using alternate

reducing gas mixture such as synthetic gas or water gas which contain CO in addition to hydrogen gas (H2) as a reducing agent. In this gas mixture the reductions due to CO occurs in the following steps:-
1. 3Fe203 + CO 2Fe304 + C02(g) ∆H = -7.8 kJ/Mol Fe
2. Fe304 + CO 3FeO + C02(g) ∆H = +11.2 kJ/Mol Fe
3. FeO + CO Fe + C02{g) ∆H = -15.7 kJ/Mol Fe
EXAMPLES
The process is carried out in Microwave Direct Reduction Furnace as mentioned earlier, the cross section view of which is shown in fig. 1/4. The Time-Temperature Profile i.e. heating profile of the Microwave Direct Reduction Furnace is illustrated in fig. 2/4.
Chemical Composition of the Iron ore used in the present invention : Fe203 -83.09, Fe (metallic) - 0.05%, FeO - 0.08%, Si02 - 4.27%, Al203 - 4.96 %, P - 0.05%, LOI-6.07
Procedure adopted in a commercial sponge iron manufacturing units for estimation of percentage metallization is described below and the same was used for the analysis in the following examples.
Weigh 0.2 gm. of sample and transfer it to a 250 ml beaker, add 2 gm of mercuric chloride anhydrous and add 100ml distilled water. Boil till the volume reduces to less than 50%. Filter the boiled solution using filter paper to remove un-dissolved residue. To this solution add 20 ml of H3P04+H2S04 mixture and 4-5 drops of barium diphenylamine suiphonate indicator. Titrate with standard K2Cr207 till solution turns from green to intense purple.

Calculations:
Determination Factor (DF): 25.5/Burette reading = A
Fe (M) = (Burette reading x 0.5585)/0.2 = B
Fe (M) = B x A
Fe (T) = Fe (M) x 0.22 + 78 x 0.9543
% Metallization = Fe (M)/Fe (T) x 100
Many modifications in addition to those described above may be made to the technique described herein without departing from the spirit and scope of the invention.
The examples given below are illustrative of the invention.
A. Direct reduction of iron ore fines obtained as mining waste for production of Sponge Iron
EXAMPLE 1
Iron ore fines as obtained from mines in Orissa were used as sample and microwave-assisted heating was carried out till the temperature of 1250°C was attained in a reducing atmosphere comprising a mixture of hydrogen gas and nitrogen gas in the percentage ratio of 8:92. The said temperature was achieved in about 42 min and the sample was soaked for 60 min in reducing atmosphere. After cooling,the sample was crushed and percentage metallization was estimated using the method described above and was estimated to be 75 %.
EXAMPLE 2
Iron ore fines as obtained from mines in Orissa were mixed with 2% lime stone powder having the chemical composition CaO - 41.73%, MgO - 1.25% and Si02 -18.26% was used and microwave-assisted heating was carried out till the temperature of 1250°C was attained in a reducing atmosphere comprising a mixture of hydrogen gas and nitrogen gas in the percentage ratio of 8:92. The said temperature was achieved in about 42 min and the sample was soaked for 60 min in reducing atmosphere. After cooling the sample was crushed and percentage

metallization was estimated using the method described above and was estimated to be 84 %.
B. Peptization and direct reduction of iron ore fines obtained as mining waste for production of Sponge Iron
EXAMPLE 3
Iron ore fines and lumps obtained from mines in Orissa were crushed and the crushed fraction passing through 150 microns mesh was used. This fraction was further converted into round pellets of about 10 mm diameter using pan granulator. During the peptization, only water was used for binding. The pellets were exposed to microwave energy till the temperature of 1100°C was attained in a reducing atmosphere comprising a mixture of hydrogen gas and nitrogen gas in the percentage ratio of 8:92. The said temperature was achieved in about 35 min and the sample was soaked for 120 min in a reducing atmosphere. After cooling ,the sample was crushed and percentage metallization was estimated using the method described above and was estimated to be 90 % (as shown in Figure 4/4).
ADVANTAGES OF THE INVENTION
1. The present process is simple, affordable and economical.
2. It is environment friendly as the waste iron ore fines which are considered as a waste in the conventional process are converted into sponge iron thereby the waste and polluting material are utilized and converted into usable material without increasing pollution.
3. The reduction is done by gas mixture consisting of Nitrogen and Hydrogen, thereby eliminating use of carbon containing reducing agent such as coal thereby drastically reducing/eliminating generation of green-house gases

4. The present process is highly energy efficient, as the input energy is utilized only for heating the raw materials and not the shell and surrounding materials.
5. In the present process ore is volumetrically, rapidly and selectively heated by microwaves thereby achieving high energy efficiency.
6. In India, the overall percentage of lumps usage in steel making (47%) is higher than most other countries and hard ore reserves are depleting. Fines form a considerable unusable part of iron ore resources which is necessary to convert into value added product such as sponge iron which is achieved by the present process.
7. The present method uses a simple design with huge economic benefits within the reach of small and large industry.
We Claim,
1. An eco-friendly method for manufacture of sponge iron from iron ore with drastic
reduction in emission of green gases, with rapid and direct reduction of iron ore in
the form of lumps/fines/pellets comprising of the following steps:
i. providing the iron ore in the form of lump/fines/pellets in a ceramic container;
ii. placing the container in a microwave cavity;
iii. volumetrically heating to 900-1250°C by applying microwave energy in a
reducing atmosphere comprising mixture of hydrogen with any inert gas; iv. soaking at 900-1250°C in a reducing atmosphere until the percentage
metallization achieved is atleast 75 % v. removing the container out of the microwave cavity cooling the container with
the contents to obtain sponge iron in the same form as the feed.
2. A method as defined in claim 1, wherein the iron ore is in the form of hematite,
magnetite, goethite, limonite, ilmenite or siderite.

3. A method as defined in claim 1, wherein the iron ore fines used are mining waste or industrial waste containing iron ore.
4. A method as defined in claim 1, wherein the diameter of iron ore fines is less than 0.5 mm and preferably less than 0.15mm.
5. A method as defined in claim 1, wherein the iron ore fines may be introduced in the form of pellets having diameter less than 40 mm but preferably uptolO mm in diameter.
6. A method as defined in claim 5, wherein the pellets are made with or without using a binder.
7. A method as defined in claim 6, wherein the binder is preferably any industrial binder such as bentonite, hydrated lime, sodium silicate or molasses .
8. A method as defined in claim 1, wherein the ceramic container used is made of microwave transparent materials such as alumina, zirconia, cordierite, mullite, quartz or using materials which act as good susceptors such as graphite, silicon carbide or mixture of transparent and susceptor material such as alumina and silicon carbide or alumina coated with graphite.
9. A method as defined in claim 1, wherein the reducing atmosphere comprises a mixture of hydrogen gas and an inert gas such as nitrogen in the percentage ratio of 5:95 to 18:82 and more preferably in the percentage ratio of 8:92 to 10:90 respectively.
10.A method as defined in claim 1, wherein the microwave energy used is in the frequency range of 800 to 5000 MHz, preferably between 890 and 2450 MHz. and more preferably 2450±50 MHz.

11. A method as defined in claim 1, wherein the heating and soaking of the said mixture is carried out preferably in the temperature range of 1100 to 1250°C and more preferably at 1100°C.
12. A method as defined in claim 1, wherein the iron ore fines or pellets are exposed to reducing atmosphere comprising a mixture of hydrogen and nitrogen gas in the percentage ratio of 8:92 till the temperature of 1100°C was achieved in about 35 min. and this was maintained in the cavity for about 2hrs to obtain sponge iron with about 90% metallization.
13. A method for rapid and direct reduction of iron ore in the form of lumps/fines/pellets resulting in metallization of iron ore, thereby producing sponge iron substantially as described in the text and examples.