Description:TECHNICAL FIELD
The present disclosure is in the field of metallurgy, particularly powder metallurgy. More particularly, the present disclosure relates to production of a dense, discoidal shaped iron powder starting from porous, irregular sponge iron powder.

BACKGROUND OF THE DISCLOSURE
Iron powders refer to the powdered form of iron typically in the range of 1 to 250 microns. Conventional iron powder manufacturing techniques are classified into Physical (Atomization, electrolytic), chemical (reduction, decomposition) and mechanical (comminution) techniques. Purity, size, shape and density of iron powders are specific to their method of synthesis and influence their end applications.
Iron powders cater to a spectrum of applications including diamond cutting tools, food fortification, water purification, metal injection moulding, electromagnetic shielding, soft magnetic composites, brake pads, welding electrodes, chemical catalysts, oxygen absorbers, etc. Among this list, certain applications like metal injection moulding, soft magnetic composites and electromagnetic shielding demand for high purity, high density iron powders.
Iron powders typically obtained by the conventional reduction route suffer from low apparent density (AD) due to their high porosity and irregular structure. Many attempts have been made by researchers to improve the density of sponge iron powders synthesized by reduction route but with limited or no success. Therefore, the need of the hour is an efficient method for obtaining high density sponge powders starting from low density iron powders or iron oxide particles. While synthesis of iron powders of various morphologies from different forms of iron has been previously discussed, synthesis of dense, discoidal shaped iron powders from irregular sponge iron is yet to be explored.

STATEMENT OF THE DISCLOSURE
Addressing the need for synthesis of dense, discoidal shaped iron powders from irregular sponge iron, the present disclosure provides a method of preparing discoidal iron powder from sponge iron powder comprising subjecting the sponge iron powder to simultaneous application of impact and friction forces by circular motion of a container comprising spherical grinding media and the sponge iron powder.
In some embodiments, the circular motion of the container comprising spherical grinding media and sponge iron powder is in clockwise direction or anti-clockwise direction or both.
In some embodiments, the circular motion of the container is at a rotation speed of at least about 900rpm, preferably about 900rpm to about 1500rpm; and/or wherein the grinding is performed for a duration of at least about 30 minutes, preferably about 30 minutes to 240 minutes. The grinding, in some embodiments, is performed at a temperature ranging from about 30°C to about 40°C.
In some embodiments, the spherical grinding media and/or the container are made of material selected from a group comprising zirconium oxide, tungsten carbide, hardened steel, stainless steel or any combination thereof.
In some embodiments, the sponge iron powder employed in the above method is prepared by
- thermal reduction of iron oxide to obtain a sponge iron cake; and
- crushing of the sponge iron cake to obtain porous, irregular sponge iron powder.
In some embodiments, the iron oxide employed for preparing the sponge iron cake comprises FeO, Fe2O3 and/or Fe3O4 optionally with Total iron content [Fe(T)] ranging from about 69% to about 73 % along with one or more of SiO2 ranging from about 0.01% to about 0.6 %, CaO ranging from about 0.01 to about 0.7 %, MnO ranging from about 0.2% to about 0.6 %, MgO ranging from about 0.01 to about 0.2 %, Al2O3 ranging from about 0.1% to about 0.7 %, Cr2O3 ranging from about 0.001% to about 0.01 %, TiO2 ranging from about 0.01 to about 0.03 %, S ranging from about 0.0001% to about 0.02 %, C ranging from about 0.02% to about 0.15 % and P ranging from about 0.005% to about 0.015 %.
In some embodiments, the thermal reduction of iron oxide for preparing the sponge iron cake is performed at a temperature ranging from about 700°C to about 1000°C, and/or wherein the thermal reduction of iron oxide is performed for a duration of about 120 minutes to about 240 minutes in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof.

In some embodiments, the obtained sponge iron powder is characterized by one or more of iron content Fe (T)) of 97 % to about 99 %, mean particle size of about 5 microns to about 150 microns, apparent density ranging from about 0.6 g/cc to about 2 g/cc, tap density ranging from about 1 g/cc to about 3 g/cc, hausner ratio ranging from about 1.3 to about 1.7, BET surface area ranging from about 0.3 m2/g to about 0.8 m2/g.
In some embodiments, the method of the present disclosure comprises –
- thermal reduction of iron oxide comprising FeO, Fe2O3 and/or Fe3O4 optionally along with one or more of SiO2, CaO, MgO, Al2O3, S, C, Cr, Ti, Cu and P, at a temperature ranging from about 700°C to about 1000°C for a duration of about 120 min to about 240 min in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof to obtain a sponge iron cake;
- crushing of the sponge iron cake by method(s) selected from a group comprising hand grinding and impact milling or a combination thereof to obtain porous, irregular sponge iron powder; and
- grinding of the porous, irregular sponge iron powder by circular motion of a zirconium oxide container comprising spherical zirconium oxide grinding media and the porous, irregular sponge iron powder at a rotation speed of at least about 900rpm, for a duration of at least about 30 minutes and at a temperature ranging from about 30°C to about 40°C in clockwise or anti-clockwise direction or both,
to obtain the discoidal iron powder.
In some embodiments, the obtained discoidal shaped iron powder is characterized by one or more of iron content of Fe (T) > 97.5 % mean particle size less than about 30 microns, apparent density of at least about 2g/cc, tap density of more than about 3.2g/cc, hausner ratio ranging from about 1.2 to about 1.5, BET surface area of not more than about 0.5 m2/g and flowability of less than about 60s/ 50 g.
In some embodiments, the obtained discoidal shaped iron powder is characterized by iron content of Fe (T) > 97.5 % mean particle size of less than about 30 microns, apparent density of at least about 2 g/cc, tap density of at least about 3.2 g/cc, hausner ratio ranging from about 1.2 to about 1.5, BET surface area of less than about 0.5m2/g and flowability of less than about 60 s/ 50g.
Further provided herein is a discoidal shaped iron powder having hausner ratio ranging from about 1.2 to 1.5.
In some embodiments, the discoidal shaped iron powder has apparent density of at least about 2g/cc.
In some embodiments, tap density of the discoidal shaped iron powder is at least about 3.2 g/cc, preferably about 3.2g/cc to about 4.1 g/cc.
In some embodiments, flowability of the discoidal shaped iron powder is less than about 60s/ 50 g, preferably about 44 s/50g to about 59 s/50g.
In some embodiments, BET surface area of the powder is not more than about 0.5 m2/g, preferably about 0.1 m2/g to about 0.5 m2/g.
In some embodiments, mean particle size of the discoidal shaped iron powder is less than about 30 microns, preferably about 5 microns to about 30 microns.
In some embodiments, iron content of the discoidal shaped iron powder (Fe(T)) is at least about 97.5%, preferably about 97.5% to about 99%.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
In order that the disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figures. The figures together with detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, where:
Figure 1 depicts X-ray powder diffraction (XRD) analysis of sponge iron powder as obtained in example 1.
Figure 2 depicts X-ray powder diffraction (XRD) analysis of discoidal iron powders as obtained in example 1.
Figure 3 depicts scanning electron micrograph (SEM) images of sponge and discoidal iron powders as obtained in example 1.
Figure 4 depicts scanning electron micrograph (SEM) images of discoidal iron powders as obtained in examples 3 and 5.
Figure 5 depicts scanning electron micrograph (SEM) images of output iron powders as obtained in examples 1 and 7-10.

DETAILED DESCRIPTION OF THE DISCLOSURE
Definitions
As used herein, the term ‘sponge iron powder’ refers to the standard meaning of the said term in the art, relating to porous or sponge-like particles of iron, having low apparent density.
As used herein, the term ‘irregular sponge iron powder’ refers to sponge iron powder as defined above, having irregular or asymmetric morphology.
As used herein, the phrase ‘pure iron powder’ or ‘spheroidal pure iron powder’ refers to the powdered iron particles comprising Fe(T) > 97.5 %.
As used herein, the phrases ‘high density iron powders’ or ‘highly dense iron powders’ or ‘dense powders’ refers to the powdered iron particles comprising apparent density of at least about 2 g/cc.
As used herein, the phrases ‘low density’ or ‘sparsely dense’ in the context of iron powders refers to the powdered iron particles comprising apparent density less than about 2 g/cc.
As used here in, ‘apparent density’ refers to the packed density of particles when they are freely packed in a volume. In a non-limiting embodiment, apparent density of the powder material is measured by Hall flow meter or Carney flow meter.
‘Tap density’ refers to the packed density of particles post subjecting the freely packed powders to tapping. As used herein, ‘hausner ratio’ refers to the ratio of tap density to apparent density of powders.
As used herein, the phrases ‘discoidal’ or ‘disk shaped’ or ‘disk like’ refers to powdered iron particles characterized by a disc-shape.
As used herein, the phrase ‘iron powder cake’ interchangeably referred to as ‘cake’ in the context of the present invention refers to the sintered iron particles in the form a fragile and easily breakable cake of any particular dimension not less than 1 mm cubic volume.
As used herein, the phrases ‘fine’ or ‘fine iron powder’ or obvious alternatives thereof refers to the powdered iron particles having mean particle size less than about 50 microns.
As used herein the phrases ‘iron oxide’ or ‘iron oxide raw material’ or ‘iron bearing oxides’ or ‘raw material’ or ‘starting material’ refers to the starting material employed in the method of the present disclosure, comprising pure iron oxide, iron oxide bearing materials and other by products comprising Fe2O3, Fe3O4, Fe2O3-Fe3O4, their derivatives and any combinations thereof.
As used herein, the term ‘comprising’ when placed before the recitation of steps in a method means that the method encompasses one or more steps that are additional to those expressly recited, and that the additional one or more steps may be performed before, between, and/or after the recited steps. For example, a method comprising steps a, b, and c encompasses a method of steps a, b, x, and c, a method of steps a, b, c, and x, as well as a method of steps x, a, b, and c. Furthermore, the term ‘comprising’ when placed before the recitation of steps in a method does not (although it may) require sequential performance of the listed steps, unless the content clearly dictates otherwise. For example, a method comprising steps a, b, and c encompasses, for example, a method of performing steps in the order of steps a, c, and b, the order of steps c, b, and a, and the order of steps c, a, and b, etc.
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. The suffix ‘(s)’ at the end of any term in the present disclosure envisages in scope both the singular and plural forms of said term.
As used in this specification and the appended claims, the singular forms ‘a’, ‘an’ and ‘the’ includes both singular and plural references unless the content clearly dictates otherwise. The use of the expression ‘at least’ or ‘at least one’ suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results. As such, the terms ‘a’ (or ‘an’), ‘one or more’, and ‘at least one’ can be used interchangeably herein.
Numerical ranges stated in the form ‘from x to y’ include the values mentioned and those values that lie within the range of the respective measurement accuracy as known to the skilled person. If several preferred numerical ranges are stated in this form, of course, all the ranges formed by a combination of the different end points are also included.
The terms ‘about’ or ‘approximately’ as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, are meant to encompass variations of and from the specified value, such as variations of +/-10% or less, +/-5% or less, +/-1% or less, and +/-0.1% or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier ‘about’ or ‘approximately’ refers is itself also specifically, and preferably, disclosed.
As used herein, the terms ‘include’, ‘have’, ‘comprise’, ‘contain’ etc. or any form said terms such as ‘having’, ‘including’, ‘containing’, ‘comprising’ or ‘comprises’ are inclusive and will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
As regards the embodiments characterized in this specification, it is intended that each embodiment be read independently as well as in combination with another embodiment. For example, in case of an embodiment 1 reciting 3 alternatives A, B and C, an embodiment 2 reciting 3 alternatives D, E and F and an embodiment 3 reciting 3 alternatives G, H and I, it is to be understood that the specification unambiguously discloses embodiments corresponding to combinations A, D, G; A, D, H; A, D, I; A, E, G; A, E, H; A, E, I; A, F, G; A, F, H; A, F, I; B, D, G; B, D, H; B, D, I; B, E, G; B, E, H; B, E, I; B, F, G; B, F, H; B, F, I; C, D, G; C, D, H; C, D, I; C, E, G; C, E, H; C, E, I; C, F, G; C, F, H; C, F, I, unless specifically mentioned otherwise.
Embodiments
As mentioned in the above section, the present disclosure is directed towards a method of preparing a discoidal iron powder. The discoidal iron powder is particularly prepared from sponge iron powder. Sponge iron generally exhibits irregular and porous morphology. It is an object of the present disclosure to utilize and impart specific forces on irregular, sparsely dense sponge iron powders in such a way that the output powders are not irregular again but possess discoidal shape with high density. Also provided herein is the synthesis of sponge iron powder suitable to produce discoidal shape iron powders with high density.
Particularly, provided herein is a method of preparing discoidal iron powder from sponge iron powder comprising subjecting the sponge iron powder to grinding by circular motion of a container comprising spherical grinding media and the sponge iron powder.
In some embodiments, the circular motion of the container comprising spherical grinding media and sponge iron powder is intended to lead to simultaneous application of impact and friction forces on the sponge iron powder.
Accordingly, provided herein is a method of preparing discoidal iron powder from sponge iron powder comprising subjecting the sponge iron powder to simultaneous application of impact and friction forces by circular motion of a container comprising spherical grinding media and the sponge iron powder.
In some embodiments, the sponge iron powder is irregular and sparsely sponge iron powder.
The impact forces acting on the powder particles allows the breakage of irregular sponge iron powder into smaller fractions and frictional forces acting between grinding media and powder particles allows the coalescence of these smaller fractions to form a dense, discoidal shape. The coalescence is a result of malleable nature of sponge iron powders.
In some embodiments, the circular motion of the container comprising the spherical grinding media and the sponge iron powder is in clockwise direction or anti-clockwise direction or both. Therefore, in some embodiments, the impact and frictional forces are simultaneously allowed to act upon particles by clockwise or anti-clockwise or both circular motion of the container comprising the spherical grinding media and the sponge iron powder.
Accordingly, in some embodiments, the method of preparing discoidal iron powder from sponge iron powder comprises subjecting the sponge iron powder to simultaneous application of impact and friction forces by circular motion of a container comprising the spherical grinding media and the sponge iron powder, wherein the circular motion of the container comprising the spherical grinding media and the sponge iron powder is in clockwise direction or anti-clockwise direction or both.
In some embodiments, the method of preparing discoidal iron powder from sponge iron powder comprises subjecting the sponge iron powder to simultaneous application of impact and friction forces by circular motion of a container comprising spherical grinding media and the sponge iron powder, wherein the circular motion of the container comprising the spherical grinding media and the sponge iron powder is in clockwise direction.
In some embodiments, the method of preparing discoidal iron powder from sponge iron powder comprises subjecting the sponge iron powder to simultaneous application of impact and friction forces by circular motion of a container comprising the spherical grinding media and the sponge iron powder, wherein the circular motion of the container comprising spherical grinding media and sponge iron powder is in anti-clockwise direction.
In some embodiments, the method of preparing discoidal iron powder from sponge iron powder comprises subjecting the sponge iron powder to simultaneous application of impact and friction forces by circular motion of a container comprising spherical grinding media and the sponge iron powder, wherein the circular motion of the container comprising spherical grinding media and sponge iron powder is in clockwise direction and anti-clockwise direction.
In some embodiments, the circular motion of the container, in clockwise direction and/or anti-clockwise direction, is at a rotation speed of at least about 900rpm, preferably about 900rpm to about 1500rpm.
In some embodiments, the circular motion of the container, in clockwise direction and/or anti-clockwise direction is at a rotation speed of about 900rpm, about 1000rpm, about 1100rpm, about 1200rpm, about 1300rpm, about 1400rpm or about 1500rpm.
In some embodiments, the circular motion of the container, in clockwise direction and/or anti-clockwise direction is for a duration of at least about 30 minutes, preferably about 30 minutes to 240 minutes.
In some embodiments, the circular motion of the container, in clockwise direction and/or anti-clockwise direction is for a duration of about 30 minutes, about 50 minutes, about 80 minutes, about 100 minutes, about 120 minutes, about 140 minutes, about 160 minutes, about 180 minutes, about 200 minutes, about 220 minutes or about 240 minutes.
In some embodiments, the circular motion of the container is at a rotation speed of about 900rpm to about 1500rpm and for a duration of about 30 minutes to 240 minutes.
In some embodiments, the grinding is performed at a temperature ranging from about 30°C to about 40°C.
In some embodiments, the grinding is performed at a temperature of about 30°C, about 31°C, about 32°C, about 33°C, about 34°C, about 35°C, about 36°C, about 37°C, about 38°C, about 39°C and about 40°C.
In some embodiments, the spherical grinding media and/or the container are made of material such as but not limited to zirconium oxide.
In some embodiments, the spherical grinding media and/or the container are made of material selected from a group comprising zirconium oxide, tungsten carbide or hardened steel or stainless steel or any combination thereof.
In some embodiments, the ratio between the spherical grinding media and the sponge iron oxide powder ranges from about 2:1 to about 10:1.
In some embodiments, the ratio between spherical grinding media size to mean particle size of sponge iron powder ranges from about 200:1 to 6:1.
In some embodiments, the sponge iron powder employed in the above method is prepared by-
- thermal reduction of iron oxide to obtain a sponge iron cake; and
- crushing of the sponge iron cake to obtain porous, irregular sponge iron powder.
In some embodiments, said method of producing the sponge iron powder yields an irregular, porous or sparsely dense sponge iron powder susceptible to processing by the method of the present disclosure to yield the discoidal iron powder. In some embodiments, the sponge iron powder, in addition to irregular morphology, is further characterized by porosity and low apparent density.
In some embodiments, the iron oxide employed as starting material to prepare the sponge iron powder by reduction comprises FeO, Fe2O3 and/or Fe3O4 optionally with Total iron content [Fe(T)] ranging from about 69% to about 73 % along with one or more of SiO2 ranging from about 0.01% to about 0.6 %, CaO ranging from about 0.01 to about 0.7 %, MnO ranging from about 0.2% to about 0.6 %, MgO ranging from about 0.01 to about 0.2 %, Al2O3 ranging from about 0.1% to about 0.7 %, Cr2O3 ranging from about 0.001% to about 0.01 %, TiO2 ranging from about 0.01 to about 0.03 %, S ranging from about 0.0001% to about 0.02 %, C ranging from about 0.02% to about 0.15 % and P ranging from about 0.005% to about 0.015 %.
In some embodiments, the iron oxide employed as starting material to prepare the sponge iron powder by reduction is mill scale iron oxide which is an oxide form of iron and is obtained as a by-product from hot stripping mill operations of a typical steel plant. In a non-limiting embodiment, the mill scale iron oxide powder comprises about 72.12% of Fe (T), about 46.82% of FeO, about 0.55% of SiO2, about 0.62% of CaO, about 0.022% of MgO, about 0.47% of MnO, about 0.22% of Al2O3, about 0.0006% of S and about 0.125% of C. Said mill scale iron oxide powder further comprises at least one or more additional elements/components selected from Cr, Ti, Cu and P at various wt% to make up the final composition to 100 wt%.
In some embodiments, the iron oxide employed as starting material to prepare the sponge iron powder by reduction is spray roasted iron oxide powder. In a non-limiting embodiment, the spray roasted iron oxide powder comprises about 69.09 of Fe(T), about 0.26% of FeO, about 0.08% of SiO2, about 0.01 of CaO, about 0.027 of MgO, about 0.38% of MnO, about 0.16 of Al2O3, about 0.01% of S and about 0.123% of C. Said spray roasted iron oxide powder further comprises at least one or more additional elements/components selected from Cr, Ti, Cu and P at various wt% to make up the final composition to 100 wt%.
In some embodiments, the thermal reduction of iron oxide is performed at a temperature ranging from about 700°C to about 1000°C.
In some embodiments, the thermal reduction of the iron oxide is performed at a temperature of about 700°C, about 750°C, about 800°C, about 850°C, about 900°C, about 950°C or about 1000°C.
In some embodiments, the thermal reduction of iron oxide is performed for a duration of about 120 minutes to about 240 minutes.
In some embodiments, the thermal reduction of the iron oxide is performed for a duration of about 120 minutes, about 140 minutes, about 160 minutes, about 180 minutes, about 200 minutes, about 220 minutes or about 240 minutes.
In some embodiments, the thermal reduction of iron oxide is performed in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof.
In some embodiments, the thermal reduction of iron oxide is performed at a temperature ranging from about 700°C to about 1000°C for a duration of about 120 minutes to about 240 minutes in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof.
In some embodiments, the thermal reduction of the iron oxide is performed at a temperature of about 700°C, about 750°C, about 800°C, about 850°C, about 900°C, about 950°C or about 1000°C for a duration of about 120 minutes, about 140 minutes, about 160 minutes, about 180 minutes, about 200 minutes, about 220 minutes or about 240 min in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof.

Accordingly, in some embodiments, the sponge iron powder is prepared by -
- thermal reduction of iron oxide comprising FeO, Fe2O3 and/or Fe3O4 at a temperature ranging from about 700°C to about 1000°C for a duration of about 120 minutes to about 240 minutes in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof to obtain a sponge iron cake; and
- crushing of the sponge iron cake to obtain porous, irregular sponge iron powder.
In some embodiments, the sponge iron powder is prepared by
- thermal reduction of iron oxide such as but not limited to mill scale iron oxide and spray roasted iron oxide or a combination thereof at a temperature ranging from about 700°C to about 1000°C for a duration of about 120 minutes to about 240 minutes in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof to obtain a sponge iron cake; and
- crushing of the sponge iron cake to obtain porous, irregular sponge iron powder.
In some embodiments, the carbon monoxide bearing gas is selected from a group comprising coke oven gas, blast furnace gas, steel making converter gas and pure carbon monoxide or any combination thereof.
In some embodiments, the hydrogen bearing gas is selected from a group comprising cracked ammonia, hydrogen separated from coke oven gas and pure hydrogen or any combination thereof.
In some embodiments, the solid carbonaceous reducing agent is selected from a group comprising graphite, charcoal, carbon black, anthracite coal, coal tar pitch and coke breeze or any combination thereof.
In some embodiments, the carbon monoxide bearing gas is selected from a group comprising coke oven gas, blast furnace gas, steel making converter gas and pure carbon monoxide or any combination thereof.
In some embodiments, the hydrogen bearing gas is selected from a group comprising cracked ammonia, hydrogen separated from coke oven gas and pure hydrogen or any combination thereof; the solid carbonaceous reducing agent is selected from a group comprising graphite, charcoal, carbon black, anthracite coal, coal tar pitch and coke breeze or any combination thereof; and/or the carbon monoxide bearing gas is selected from a group comprising coke oven gas, blast furnace gas, steel making converter gas and pure carbon monoxide or any combination thereof.
In some embodiments, the reduction of iron oxide to obtain the sponge iron cake is performed in a furnace such as but not limited to a tubular-type furnace, continuous belt furnace, pusher type furnace, muffle furnace.
In some embodiments, the crushing is performed by method(s) selected from but not limited to hand grinding, jaw crushing, hammer milling and impact milling or any combination thereof. The crushing is performed with the objective of pulverizing and/or converting the sponge iron cake into its powder form and may thus be performed by any method routinely adopted in the art for producing a powder from a bigger mass.
Accordingly, in some embodiments, the sponge iron powder is prepared by
- thermal reduction of iron oxide comprising FeO, Fe2O3 and/or Fe3O4 at a temperature ranging from about 700°C to about 1000°C for a duration of about 120 min to about 240 min in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof to obtain a sponge iron cake; and
- crushing of the sponge iron cake by method(s) selected from but not limited to hand grinding, jaw crushing, hammer milling and impact milling or any combination thereof to obtain porous, irregular sponge iron powder.
In some embodiments, the sponge iron powder is prepared by
- thermal reduction of iron oxide such as but not limited to mill scale iron oxide and spray roasted iron oxide or a combination thereof at a temperature ranging from about 700°C to about 1000°C for a duration of about 120 min to about 240 min in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof to obtain a sponge iron cake; and
- crushing of the sponge iron cake by method(s) selected from but not limited to hand grinding, jaw crushing, hammer milling and impact milling or any combination thereof to obtain porous, irregular sponge iron powder.
In some embodiments, the obtained porous, irregular sponge iron powder is characterized by iron content [Fe (T)] of about 97 % to about 99 %. In some embodiments, the obtained irregular sponge iron powder is characterized by iron content [Fe (T)] of about 97%, about 98% or about 99%.
In some embodiments, the obtained porous, irregular sponge iron powder is characterized by mean particle size of about 5 microns to about 150 microns, preferably less than 75 microns, more preferably about 5 microns to about 75 microns. In some embodiments, the obtained porous, irregular sponge iron powder is characterized by mean particle size of about 5 microns, about 15 microns, about 25 microns, about 35 microns, about 45 microns, about 55 microns, about 60 microns or about 75 microns.
In some embodiments, the obtained porous, irregular sponge iron powder is characterized by apparent density ranging from about 0.6 g/cc to about 2 g/cc. In some embodiments, the obtained porous, irregular sponge iron powder is characterized by apparent density ranging of about 0.6 g/cc, about 0.7 g/cc, about 0.8 g/cc, about 0.9 g/cc, about 1 g/cc, about 1.1 g/cc, about 1.2 g/cc, about 1.3 g/cc, about 1.4 g/cc, about 1.5 g/cc, about 1.6 g/cc, about 1.7 g/cc, about 1.8 g/cc, about 1.9 g/cc or about 2 g/cc.
In some embodiments, the obtained irregular sponge iron powder is characterized by tap density ranging from about 1 g/cc to about 3 g/cc. In some embodiments, the obtained porous, irregular sponge iron powder is characterized by tap density of about 1 g/cc, about 1.5 g/cc, about 2 g/cc, about 2.5 g/cc or about 3 g/cc.
In some embodiments, the obtained porous, irregular sponge iron powder is characterized by hausner ratio ranging from about 1.3 to about 1.8. In some embodiments, the obtained porous,irregular sponge iron powder is characterized by hausner ratio of about 1.3, about 1.4, about 1.5, about 1.6, about 1.7 or about 1.8
In some embodiments, the obtained porous, irregular sponge iron powder is characterized by BET surface area ranging from about 0.3 m2/g to about 0.8 m2/g. In some embodiments, the obtained porous, irregular sponge iron powder is characterized by BET surface area of about 0.3 m2/g, about 0.4 m2/g, about 0.5 m2/g, about 0.6 m2/g, about 0.7 m2/g or about 0.8 m2/g.
In some embodiments, the obtained porous, irregular sponge iron powder is characterized by one or more of iron content Fe (T)) of 97 % to about 99 %, mean particle size of 5 microns to about 150 microns, preferably about 5 microns to about 75 microns, apparent density ranging from about 0.6 g/cc to about 2 g/cc, tap density ranging from about 1 g/cc to about 3 g/cc, hausner ratio ranging from about 1.3 to about 1.8 and BET surface area ranging from about 0.3 m2/g to about 0.8 m2/g.
In a non-limiting embodiment, the obtained porous, irregular sponge iron powder synthesized from spray roasted iron oxide is not flowable.
In some embodiments, the method of the present disclosure comprises –
- thermal reduction of iron oxide comprising FeO, Fe2O3 and/or Fe3O4 optionally along with one or more of SiO2, CaO, MgO, Al2O3, S, C, Cr, Ti, Cu and P, at a temperature ranging from about 700°C to about 1000°C for a duration of about 120 min to about 240 min in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof to obtain a sponge iron cake;
- crushing of the sponge iron cake by method(s) selected from but not limited to hand grinding, jaw crushing, hammer milling and impact milling or any combination thereof. to obtain porous, irregular sponge iron powder; and
- grinding of the porous, irregular sponge iron powder by circular motion of a zirconium oxide container comprising spherical zirconium oxide grinding media and the porous, irregular sponge iron powder at a rotation speed of at least about 900rpm, for a duration of at least about 30 minutes and at a temperature ranging from about 30°C to about 40°C in clockwise or anti-clockwise direction or both,
to obtain the discoidal iron powder.

In some embodiments, the obtained discoidal shaped iron powder is characterized by iron content [Fe (T)] of at least about 97.5 %, preferably about 97.5% to about 99%.
In some embodiments, the obtained discoidal shaped iron powder is characterized by mean particle size of less than about 30 microns, preferably about 5 microns to about 30 microns.
In some embodiments, the obtained discoidal shaped iron powder is characterized by apparent density of at least about 2g/cc, preferably at least about 2.4 g/cc, more preferably about 2.4 g/cc to about 3.4 g/cc.
In some embodiments, the obtained discoidal shaped iron powder is characterized by tap density of at least about 3.2 g/cc, preferably about 3.2g/cc to 4.1g/cc.
In some embodiments, the obtained discoidal shaped iron powder is characterized by hausner ratio ranging from about 1.2 to about 1.5.
In some embodiments, the obtained discoidal shaped iron powder is characterized by BET surface area of not more than about 0.5 m2/g, preferably about 0.1 m2/g to about 0.5 m2/g,
In some embodiments, the obtained discoidal shaped iron powder is characterized by flowability of less than about 60s/50 g, preferably about 44 s/50g to about 59 s/50g.
In some embodiments, the obtained discoidal shaped iron powder is characterized by one or more of iron content [Fe (T)] of at least about 97.5 %, mean particle size of less than about 30 microns, apparent density of at least about 2g/cc, tap density of at least about 3.2 g/cc, hausner ratio ranging from about 1.2 to about 1.5, BET surface area of not more than about 0.5 m2/g and flowability of less than about 60s/50 g.
In some embodiments, the obtained discoidal shaped iron powder is characterized by iron content of [Fe(T)] of at least about 97.5 %, mean particle size of less than about 30 microns, apparent density of at least about 2 g/cc, tap density of at least about 3.2 g/cc, hausner ratio ranging from about 1.2 to about 1.5, BET surface area of not more than about 0.5m2/g and flowability of less than about 60 s/ 50g.
Purity, size, shape and density of iron powders are dependent on their method of synthesis which further, influences their end applications. The discoidal shape of the obtained iron powder with high apparent density, high tap density and low hausner ratio exhibits efficient packing of powder which in-turn benefits the process of sintering in applications like metal injection molding.
Accordingly, further provided herein is a discoidal shaped iron powder characterized by hausner ratio ranging from about 1.2 to about 1.5. In some embodiments, the discoidal shaped iron powder has hausner ratio of about 1.2, about 1.3, about 1.4 or about 1.5.
In some embodiments, the discoidal shaped iron powder of the present disclosure has apparent density of at least about 2g/cc. In some embodiments, the discoidal shaped iron powder has apparent density of at least about 2.4g/cc, preferably about 2.4g/cc to about 3.4 g/cc. In some embodiments, the discoidal shaped iron powder has apparent density of about 2.4g/cc, about 2.5g/cc, about 2.6g/cc, about 2.7g/cc, about 2.8g/cc, about 2.9g/cc, about 3g/cc, about 3.1g/cc, about 3.2g/cc, about 3.3 g/cc or about 3.4g/cc.
In some embodiments, the discoidal shaped iron powder of the present disclosure has hausner ratio ranging from about 1.2 to about 1.5 and apparent density ranging from about 2.4g/cc to about 3.4 g/cc.
In some embodiments, tap density of the discoidal shaped iron powder of the present disclosure is at least about 3.2 g/cc. In some embodiments, tap density of the discoidal shaped iron powder ranges from about 3.2g/cc to about 4.1 g/cc. In some embodiments, tap density of the discoidal shaped iron powder is about 3.2g/cc, about 3.3g/cc, about 3.4g/cc, about 3.5g/cc, about 3.6g/cc, about 3.7g/cc, about 3.8g/cc, about 3.9g/cc, about 4g/cc or about 4.1g/cc.
In some embodiments, the discoidal shaped iron powder of the present disclosure has hausner ratio ranging from about 1.2 to about 1.5, apparent density ranging from about 2.4g/cc to about 3.4 g/cc and tap density ranging from about 3.2g/cc to about 4.1 g/cc.
In some embodiments, flowability of the discoidal shaped iron powder of the present disclosure is less than about 60s/ 50 g. In some embodiments, flowability of the discoidal shaped iron powder ranges from about 44s/50g to about 58s/50g. In some embodiments, flowability of the discoidal shaped iron powder is about 44s/50g, about 46s/50g, about 48s/50g, about 50s/50g, about 52s/50g, about 54s/50g, about 56s/50g or about 58s/50g.
In some embodiments, the discoidal shaped iron powder of the present disclosure has hausner ratio ranging from about 1.2 to about 1.5, apparent density ranging from about 2.4g/cc to about 3.4 g/cc, tap density ranging from about 3.2g/cc to about 4.1 g/cc and flowability of less than about 60s/ 50 g.
In some embodiments, BET surface area of the discoidal shaped iron powder of the present disclosure is less than about 0.5m2/g. In some embodiments, BET surface area of the powder ranges from about 0.1m2/g to about 0.5m2/g. In some embodiments, BET surface area of the powder is about 0.1m2/g, about 0.2m2/g, about 0.3m2/g, about 0.4m2/g or about 0.5m2/g.
In some embodiments, the discoidal shaped iron powder of the present disclosure has hausner ratio ranging from about 1.2 to about 1.5, apparent density ranging from about 2.4g/cc to about 3.4 g/cc, tap density ranging from about 3.2g/cc to about 4.1 g/cc, flowability of less than about 60s/50 g and BET surface area less than about 0.5m2/g.

In some embodiments, the discoidal shaped iron powder of the present disclosure has mean particle size of less than about 30 microns, preferably about 5 microns to 30 microns. In some embodiments, the discoidal shaped iron powder is therefore a fine iron powder.

In some embodiments, the discoidal shaped iron powder of the present disclosure has hausner ratio ranging from about 1.2 to about 1.5, apparent density ranging from about 2.4g/cc to about 3.4 g/cc, tap density ranging from about 3.2g/cc to about 4.1 g/cc, flowability of less than about 60s/50 g, BET surface area less than about 0.5m2/g and particle size of less than about 30 microns.

In some embodiments, iron content [Fe(T)] of the discoidal shaped iron powder of the present disclosure is at least about 97.5%, preferably about 97.5% to about 99%. In some embodiments, iron content of the discoidal shaped iron powder (Fe(T)) is about 97.5%, about 97.6%, about 97.7%, about 97.8%, about 97.9%, about 98%, about 98.1%, about 98.2%, about 98.3%, about 98.4%, about 98.5%, about 98.6%, about 98.7%, about 98.8%, about 98.9% or about 99%.
In some embodiments, the discoidal shaped iron powder of the present disclosure has hausner ratio ranging from about 1.2 to about 1.5, apparent density ranging from about 2.4g/cc to about 3.4 g/cc, tap density ranging from about 3.2g/cc to about 4.1 g/cc, flowability of less than about 60s/50 g, BET surface area less than about 0.5m2/g, particle size of less than about 30 microns and (Fe(T)) of at least about 97.5%.
Taken together, the method of the present disclosure is a simple method that allows utilization specific forces on irregular spongy iron powders in such a way that the output powders are discoidal shaped iron powders at least characterized by properties of high density and low hausner ratio.
In an embodiment, the foregoing descriptive matter is illustrative of the disclosure and not a limitation. Providing working examples for all possible combinations of optional elements in the composition and process parameters such as but not limiting to time and temperature of hot dipping, is considered redundant.

While the present disclosure is susceptible to various modifications and alternative forms, specific aspects thereof have been shown by way of examples and drawings and are described in detail below. However, it should be understood that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and the scope of the invention as defined by the appended claims.

EXAMPLES:

Example 1: Preparing discoidal iron powder by the method of the present invention
Sponge iron powder was synthesized by reduction of iron oxide at about 850 0C for a duration of about 240 min under gaseous cracked ammonia atmosphere in a tubular type furnace to obtain a sponge iron cake, followed by jaw crushing and hammer milling of the cake to obtain the sponge iron powder. The obtained sponge iron powder had Fe(T) of about 98.59%, mean particle size of about 27.5 microns, apparent density of about 0.99 g/cc, tap density of about 1.58 g/cc, hausner ratio of about 1.59, and BET surface area of about 0.411 m2/g.
The sponge iron powder as obtained above was placed in a zirconium oxide container along with zirconium oxide grinding media such that the ratio between the sponge iron powder and the grinding media was about 1:5. Impact and friction forces were simultaneously imparted over sponge iron powders for a period of about 60 minutes in clockwise motion at a rotation speed of about 1500 rpm.
The obtained discoidal iron powders possessed Fe(T) of about 98%, mean particle size of about 20.1 microns, apparent density of about 3.3 g/cc, tap density of about 4.03 g/cc, hausner ratio of about 1.22, BET surface area of about 0.23 m2/g and flowability of about 44 s/50 g. XRD analysis of the sponge iron powder and discoidal iron powder obtained therefrom is shown in Figures 1 and 2, respectively reveals the powders obtained without any contamination. SEM analysis of the sponge and discoidal iron powders are shown Figure 3a and 3b respectively.

Example 2: Preparing discoidal iron powder by the method of the present invention
Sponge iron powder was synthesized by reduction of iron oxide at about 800 0C for a duration of about 240 minutes under gaseous hydrogen atmosphere in a tubular type furnace to obtain a sponge iron cake, followed by jaw crushing of the cake to obtain the sponge iron powder. The obtained sponge iron powder possessed Fe(T) of about 98.3%, mean particle size of about 47 microns, apparent density of about 0.76 g/cc, tap density of about 1.2 g/cc, hausner ratio of about 1.57 and BET surface area of about 0.36 m2/g.

The sponge iron powder as obtained above was placed in a zirconium oxide container along with zirconium oxide grinding media such that the ratio between the sponge iron powder and the grinding media was about 1:5. Impact and friction forces were simultaneously imparted over sponge iron powders for a period of about 60 minutes in clockwise motion at a rotation speed of about 1500 rpm.

The obtained discoidal iron powders possessed Fe(T) of about 98.05%, mean particle size of about 23.3 microns, apparent density of about 3.33 g/cc, tap density of about 4 g/cc, hausner ratio of about 1.2, BET surface area of about 0.163 m2/g and flowability of= about 45 s/50g.

Example 3: Preparing discoidal iron powder by the method of the present invention
Sponge iron powder was synthesized by reduction of iron oxide at about 800 0C for a duration of about 240 minutes under gaseous hydrogen atmosphere in a tubular type furnace to obtain a sponge iron cake, followed by hammer milling of the cake to obtain the sponge iron powder. The obtained sponge iron powder possessed Fe(T) of about 98.3%, mean particle size of about 32.7 microns, apparent density of about 0.85 g/cc, tap density of about 1.37 g/cc, hausner ratio of about 1.61 and BET surface area of about 0.437 m2/g.
The sponge iron powder as obtained above was placed in a zirconium oxide made container along with zirconium oxide made grinding media such that the ratio between the sponge iron powder and the grinding media was about 1:5. Impact and friction forces were simultaneously imparted over sponge iron powders using zirconium oxide made grinding media in a zirconium oxide made container for a period of about 60 minutes in clockwise motion at a rotation speed of about 1200 rpm. The obtained discoidal iron powders possessed Fe(T) of about 97.9%, mean particle size of about 17.3 microns, apparent density of about 2.58 g/cc, tap density of about 3.22 g/cc, hausner ratio of about 1.24, BET surface area of about 0.47 m2/g and flowability of about 47 s/50 g. SEM analysis of the obtained discoidal iron powder is shown in Figure 4a.

Example 4: Preparing discoidal iron powder by the method of the present invention
Sponge iron powder was synthesized by reduction of iron oxide at about 700 0C for a duration of about 240 minutes under gaseous hydrogen atmosphere in a tubular type furnace to obtain a sponge iron cake, followed by jaw crushing of the cake to obtain the sponge iron powder. The obtained sponge iron powder possessed Fe(T) of about 98.3%, mean particle size of about 37.4 microns, apparent density of about 0.69 g/cc, tap density of about 1.17 g/cc, hausner ratio of about 1.69 and BET surface area of about 0.79 m2/g.

The sponge iron powder as obtained above was placed in a zirconium oxide made container along with zirconium oxide made grinding media such that the ratio between the sponge iron powder and the grinding media was about 1:5. Impact and friction forces were simultaneously imparted over sponge iron powders using zirconium oxide made grinding media in a zirconium oxide made container for a period of about 60 minutes in anti-clockwise motion at a rotation speed of about 1500 rpm. The obtained discoidal iron powders possessed Fe(T) of about 97.8, mean particle size of about 7.3 microns, apparent density of about 2.45 g/cc, tap density of about 3.59 g/cc, hausner ratio of about 1.46 and BET surface area of about 0.5 m2/g.

Example 5: Preparing discoidal iron powder by the method of the present invention
Sponge iron powder was synthesized by reduction of iron oxide at about 700 0C for a duration of about 240 minutes under gaseous hydrogen atmosphere in a tubular type furnace to obtain a sponge iron cake, followed by hammer milling of the cake to obtain the sponge iron powder. The obtained sponge iron powder possessed Fe(T) of about 98.5%, mean particle size of about 26.7 microns, apparent density of about 0.66 g/cc, tap density of about 1.13 g/cc, hausner ratio of about 1.71 and BET surface area of about 0.75 m2/g.
The sponge iron powder as obtained above was placed in a zirconium oxide made container along with zirconium oxide made grinding media such that the ratio between the sponge iron powder and the grinding media was about 1:5. Impact and friction forces were simultaneously imparted over sponge iron powders using zirconium oxide made grinding media in a zirconium oxide made container for a period of -30 minutes in clockwise and about 30 minutes in anti-clockwise motion at a rotation speed of about 1500 rpm.
The obtained discoidal iron powders possessed Fe(T) of about 97.6%, mean particle size of about 8.4 microns, apparent density of about 2.51 g/cc, tap density of about 3.58 g/cc, hausner ratio about 1.42 and BET surface area of about 0.382 m2/g. SEM analysis of the obtained discoidal iron powder is shown in Figure 4b.

Example 6: Preparing discoidal iron powder by the method of the present invention
Sponge iron powder was synthesized by reduction of iron oxide at about 850 0C for a duration of about 240 minutes under gaseous cracked ammonia atmosphere in a tubular type furnace to obtain a sponge iron cake, followed by jaw crushing and hammer milling of the cake to obtain the sponge iron powder. The obtained sponge iron powder possessed Fe(T) of about 98.59%, mean particle size of about 27.5 microns, apparent density of about 0.99 g/cc, tap density of about 1.58 g/cc, hausner ratio of about 1.59 and BET surface area of about 0.411 m2/g.
The sponge iron powder as obtained above was placed in a zirconium oxide made container along with zirconium oxide made grinding media such that the ratio between the sponge iron powder and the grinding media was about 1:5. Impact and friction forces were simultaneously imparted over sponge iron powders using zirconium oxide made grinding media in a zirconium oxide made container for a period of about 120 min in clockwise motion at a rotation speed of about 1500 rpm. The obtained discoidal iron powders possessed Fe(T) of about 98.07%, mean particle size of about 15.5 microns, apparent density of about 3.13 g/cc, tap density of about 3.85 g/cc, hausner ratio of about 1.23, BET surface area of about 0.22 m2/g and flowability of about 58 s/50g.

Table 1 below provides an overview of properties of discoidal iron powders synthesized from sponge iron powders in each of the above examples:

Table 1: Characterization of sponge iron powder and discoidal iron powder of Examples 1-6
Example Sponge iron powder Discoidal iron powder
Fe(T) D50 (µm) AD (g/cc) BET (m2/g) TD (g/cc) Hasuner ratio Fe(T) D50 (µm) AD (g/cc) BET (m2/g) TD
(g/cc) Hausner
ratio Flowability
(s/ 50 g)
Example 1 98.59 27.5 0.99 0.411 1.58 1.59 98 20.1 3.3 0.23 4.03 1.22 44
Example 2 98.3 47 0.76 0.36 1.2 1.57 98.05 23.3 3.33 0.163 4 1.2 45
Example 3 98.3 32.7 0.85 0.437 1.37 1.61 97.9 17.3 2.58 0.47 3.22 1.24 47
Example 4 98.3 37.4 0.69 0.79 1.17 1.69 97.8 7.3 2.45 0.5 3.59 1.46 NM*
Example 5 98.5 26.7 0.66 0.75 1.13 1.71 97.6 8.4 2.51 0.382 3.58 1.42 NM*
Example 6 98.59 27.5 0.99 0.411 1.58 1.59 98.07 15.5 3.13 0.22 3.85 1.23 58
*NM – not measured

Example 7: Comparative example analysing impact of the process of the present disclosure characterized by application of a combination of simultaneous impact and friction forces
As a continuation to Examples 1-6, Experiments 7-10 were performed following similar procedure as set out in the previous examples, however, replacing the forces applied on the sponge iron powder in the said examples with alternative forces such as Compression forces individually (Example 7), Impact forces individually (Example 8), Impact and shear forces simultaneously (Example 9) and Impact and Compression forces simultaneously (Example 10). Accordingly, suitable media for application of the respective forces as defined above was used in the said examples. The results observed are provided in the below table -2
Table 2: Impact of application of different forces on sponge iron powder
Example 1 (as per the present disclosure) Example 7 Example 8 Example 9 Example 10
Feed Sponge iron powder Sponge iron powder Sponge iron powder Sponge iron powder Sponge iron powder
Force applied on powder Simultaneous impact and friction Compression Impact Simultaneous impact and shear Simultaneous impact and compression
Media used for grinding Moving Spheres Pressurized cylindrical rolls Moving rectangular jaw Moving sharp rectangular jaw Pressurized rectangular jaws
Morphology of powder obtained Discoidal shape Flattened shape Irregular shape Irregular shape Irregular shape
Hausner ratio 1.22 1.59 1.61 1.61 1.58
AD (g/cc) 3.3 1.3 0.85 1.22 0.76
TD (g/cc) 4.03 2.06 1.35 1.96 1.2

It was observed that the process of the present disclosure characterized by the simultaneous application of impact and friction forces yielded discoidal shaped powders with low Hausner ratio and high Apparent and Tap densities. Replacing the said forces with alternate forces or impact forces alone as opposed to a combination of impact and friction forces yielded particles having different morphology, comparatively higher Hausner ratio and lower Apparent and Tap densities. The morphologies of the obtained powders are depicted in Figures 5(a)-5(e).

Additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based on the description provided herein. The embodiments herein provide various features and advantageous details thereof in the description. Descriptions of well-known/conventional methods and techniques are omitted so as to not unnecessarily obscure the embodiments herein.

The foregoing description fully reveals the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments in this disclosure have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein, without departing from the principles of the disclosure.

Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
, Claims:
1) A method of preparing discoidal iron powder from sponge iron powder comprising subjecting the sponge iron powder to simultaneous application of impact and friction forces by circular motion of a container comprising spherical grinding media and the sponge iron powder.
2) The method as claimed in claim 1, wherein the circular motion of the container comprising spherical grinding media and sponge iron powder is in clockwise direction or anti-clockwise direction or both.
3) The method as claimed in claim 1, wherein the circular motion of the container is at a rotation speed of at least about 900rpm, preferably about 900rpm to about 1500rpm; and/or wherein the grinding is performed for a duration of at least about 30 minutes, preferably about 30 minutes to 240 minutes.
4) The method as claimed in claim 1, wherein the grinding is performed at a temperature ranging from about 30°C to about 40°C.
5) The method as claimed in claim 1, wherein the spherical grinding media and/or the container are made of material selected from a group comprising zirconium oxide, tungsten carbide, hardened steel, stainless steel or any combination thereof.
6) The method as claimed in claim 1, wherein the sponge iron powder is prepared by
- thermal reduction of iron oxide to obtain a sponge iron cake; and
- crushing of the sponge iron cake to obtain porous, irregular sponge iron powder.
7) The method as claimed in claim 6, wherein the iron oxide comprises FeO, Fe2O3 and/or Fe3O4 optionally with Total iron content [Fe(T)] ranging from about 69% to about 73 % along with one or more of SiO2 ranging from about 0.01% to about 0.6 %, CaO ranging from about 0.01 to about 0.7 %, MnO ranging from about 0.2% to about 0.6 %, MgO ranging from about 0.01 to about 0.2 %, Al2O3 ranging from about 0.1% to about 0.7 %, Cr2O3 ranging from about 0.001% to about 0.01 %, TiO2 ranging from about 0.01 to about 0.03 %, S ranging from about 0.0001% to about 0.02 %, C ranging from about 0.02% to about 0.15 % and P ranging from about 0.005% to about 0.015 %.

8) The method as claimed in claim 6, wherein thermal reduction of iron oxide is performed at a temperature ranging from about 700°C to about 1000°C, and/or wherein the thermal reduction of iron oxide is performed for a duration of about 120 minutes to about 240 minutes in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof.
9) The method as claimed in claim 8, wherein the carbon monoxide bearing gas is selected from a group comprising coke oven gas, blast furnace gas, steel making converter gas and pure carbon monoxide or any combination thereof; wherein the hydrogen bearing gas is selected from a group comprising cracked ammonia, hydrogen separated from coke oven gas and pure hydrogen or any combination thereof; and/or wherein the solid carbonaceous reducing agent is selected from a group comprising graphite, charcoal, carbon black, anthracite coal, coal tar pitch and coke breeze or any combination thereof.
10) The method as claimed in claimed in claim 6, wherein the crushing is performed by method(s) selected from a group comprising hand grinding, hammer milling and impact milling or any combination thereof.
11) The method as claimed in claim 6, wherein the obtained sponge iron powder is characterized by one or more of iron content Fe (T)) of 97 % to about 99 %, mean particle size of about 5 microns to about 150 microns, apparent density ranging from about 0.6 g/cc to about 2 g/cc, tap density ranging from about 1 g/cc to about 3 g/cc, hausner ratio ranging from about 1.3 to about 1.7, BET surface area ranging from about 0.3 m2/g to about 0.8 m2/g.
12) The method as claimed in claim 1, comprising –
- thermal reduction of iron oxide comprising FeO, Fe2O3 and/or Fe3O4 optionally along with one or more of SiO2, CaO, MgO, Al2O3, S, C, Cr, Ti, Cu and P, at a temperature ranging from about 700°C to about 1000°C for a duration of about 120 min to about 240 min in presence of solid and/or gaseous reducing agent(s) selected from a group comprising carbon, carbonaceous products, hydrogen, hydrogen bearing gases, carbon monoxide and carbon monoxide bearing gases or any combination thereof to obtain a sponge iron cake;
- crushing of the sponge iron cake by method(s) selected from a group comprising hand grinding and impact milling or a combination thereof to obtain porous, irregular sponge iron powder; and
- grinding of the porous, irregular sponge iron powder by circular motion of a zirconium oxide container comprising spherical zirconium oxide grinding media and the porous, irregular sponge iron powder at a rotation speed of at least about 900rpm, for a duration of at least about 30 minutes and at a temperature ranging from about 30°C to about 40°C in clockwise or anti-clockwise direction or both,
to obtain the discoidal iron powder.
13) The method as claimed in claim 1, wherein the obtained discoidal shaped iron powder is characterized by one or more of iron content of Fe (T) > 97.5 % mean particle size less than about 30 microns, apparent density of at least about 2g/cc, tap density of more than about 3.2g/cc, hausner ratio ranging from about 1.2 to about 1.5, BET surface area of not more than about 0.5 m2/g and flowability of less than about 60s/ 50 g.
14) The method as claimed in claim 1, wherein the obtained discoidal shaped iron powder is characterized by iron content of Fe (T) > 97.5 % mean particle size of less than about 30 microns, apparent density of at least about 2 g/cc, tap density of at least about 3.2 g/cc, hausner ratio ranging from about 1.2 to about 1.5, BET surface area of less than about 0.5m2/g and flowability of less than about 60 s/ 50g.
15) A discoidal shaped iron powder having hausner ratio ranging from about 1.2 to 1.5.
16) The discoidal shaped iron powder as claimed in claim 15, having apparent density of at least about 2g/cc.
17) The discoidal shaped iron powder as claimed in claim 16, wherein the apparent density is at least about 2.4g/cc, preferably about 2.4g/cc to about 3.4 g/cc.
18) The discoidal shaped iron powder as claimed in claim 15, wherein tap density of the discoidal shaped iron powder is at least about 3.2 g/cc, preferably about 3.2g/cc to about 4.1 g/cc.
19) The discoidal shaped iron powder as claimed in claim 15, wherein flowability of the discoidal shaped iron powder is less than about 60s/ 50 g, preferably about 44 s/50g to about 59 s/50g.
20) The discoidal shaped iron powder as claimed in claim 15, wherein BET surface area of the powder is not more than about 0.5 m2/g, preferably about 0.1 m2/g to about 0.5 m2/g.
21) The discoidal shaped iron powder as claimed in claim 15, wherein mean particle size of the discoidal shaped iron powder is less than about 30 microns, preferably about 5 microns to about 30 microns.
22) The discoidal shaped iron powder as claimed in claim 15, wherein iron content of the discoidal shaped iron powder (Fe(T)) is at least about 97.5%, preferably about 97.5% to about 99%.