CROSS-REFERENCE TO RELATED APPLICATIONS AND DOCUMENTS

The present application claims priority from U.S. provisional patent application 62/809, 81 1 filed on February 25, 2019 and herewith included in its entirety.

TECHNOLOGICAL FIELD

The present disclosure relates to fine iron metallic powders as well as processes for making and using same.

BACKGROUND

There exists fine iron powder formulations, namely: carbonyl iron powder (CIP), direct reduced iron powder (DRI) and electrolytic iron powder (EIP). Fine iron powder products can also be obtained by size selection of high pressure water atomised powder (WAP).

The use of CIP is in limited practice, as the technology is closely held, with dangerous intermediates and the CIP product is relatively expensive. It also has limited particle size range capability in the finer range, generally around 5 microns. The CIP powder is spherical.

The DRI powder is made by hydrogen reduction of fine iron oxide, usually hematite (Fe ₂ 0 ₃ ). The resulting product can be made fine, but is typically‘sponge-like’ with high porosity due to the relative proportion of oxygen in the raw feed material and the holes left behind by removal of this much oxygen.

EIP is practiced at a relatively small scale. The powder, like all electrolytic metal powder, is dendritic in shape with high surface area, but low apparent density, poor flowability and susceptible to oxidation. The electrolytic process has inherent difficulties scaling up.

WAP is the most common commercial production method to produce iron powder. The average particle size is most commonly in the range of 75 to 150 microns. While a normal size distribution would include fine iron powder in the below 325 mesh (44 micron range), the yield is low, on the order of 10%, and the processing cost is correspondingly high. The oversize product, typically 90% of the total size distribution, has limited value.

It would be desirable to be provided with a fine iron powder having a particle size in the mm range, and/or in which the oxygen is located as mostly surface oxide (so as to avoid leaving holes behind when removing oxygen in the reduced powder) to be provided in higher apparent density for a similar particle size, which in turn would increase density and performance of the powder when consolidated into a shape. In some embodiments, it would also be preferable, the powder could be agglomerated to produce sponge-like powder by appropriate choice of thermal treatment. In some embodiments, the fine iron powder would feature a small particle size, a high packing density near-spherical shape, high purity and superior sinterability. In some embodiments, a relatively high level of C and O can be found in the final iron powder depending on the process used.

BRIEF SUMMARY

The present disclosure provides the use of high-energy milling, such as attrition milling, to reduce the particle size of a brittle and coarse high carbon iron composition to make a metallic iron powder having finer particles.

According to a first aspect, the present disclosure provides a metallic iron powder having fine particles, wherein 90% of the fine particles have a particle size below 45 mm. The fine particles comprise, in weight percentage: between about 0.0001 and about 4.3 C; up to about 10.0 O, optionally ferro-alloying elements; and the balance being Fe an inevitable impurities. In an embodiment, 90% of the fine particles have a particle size below 20 mm. In yet another embodiment, 50% of the fine particles have a particle size below 10 mm. In an embodiment, when the powder is provided in an annealed form, it can have between about 0.01 to about 2.0 O In an embodiment, when the powder is provided in an non-annealed form, it can have between about 0.1 to about 10.0 O. In an embodiment, the metallic iron powder has an angle of repose of between about 40 and about 50 degrees. In still another embodiment, the metallic iron powder has an apparent density of between about 1.5 and about 2.5 g/cc. In yet another embodiment, the metallic iron powder has a tap density of between about 3.0 and about 4.5 g/cc.

According to a second aspect, the present disclosure provides a process for making a metallic iron powder. The process comprises (a) providing a feed consisting essentially of a solid high carbon iron composition having coarse particles; (b) submitting the feed and a milling medium to high-energy milling to obtain a high energy-milled iron composition having fine particles, wherein the average particle size D ₅₀ of the fine particles of the high energy-milled composition is lower than the D ₅₀ of the coarse particles; and (c) screening, sieving or classifying the high energy-milled iron composition for particles having an average size of 45 mm or less to obtain the metallic iron powder, wherein 90% of the particles of the metallic iron powder have a particle size below 45 mm. In the process, the solid high carbon iron composition comprises, in weight percent: between about 0.77 and about 6.67 C; between about 0.1 to 10.0 O; optionally ferro- alloying elements and the balance being Fe and inevitable impurities. The solid high carbon composition comprises cementite. The average particle size of the coarse particles of the solid high carbon iron composition can be between about 50 to about 400 mm, and in some additional embodiments between about 100 to about 200 mm. In an embodiment, high-energy milling is attrition milling (and it provides an attrition-milled composition). In yet another embodiment, the process further comprises, prior to step (a), submitting a liquid high carbon iron composition to water atomisation to provide an atomized high carbon iron composition for making the feed. In yet another embodiment, the process further comprises, prior to step (a), submitting the atomized high carbon iron composition to magnetic separation and/or vacuum filtration to obtain a separated high carbon iron composition for making the feed. In still a further embodiment, the process further comprises, prior to step (a), submitting the separated high carbon iron composition to ball milling to obtain a ball-milled high carbon iron composition for making the feed. In yet another embodiment, the process further comprises, prior to step (a), submitting the ball-milled high carbon iron composition to a screening, sieving or classifying step for fine particles having an average size of 45 mm or less for making the metallic iron powder. In still a further embodiment, the process further comprises, after step (c), submitting the metallic iron powder to a thermal treatment to obtain a heat-treated high carbon iron powder. In yet a further embodiment, the process further comprises, after step (c), submitting the heat-treated metallic iron powder to disc milling to obtain a disc-milled high carbon iron powder. In yet another embodiment, the process further comprises, screening, sieving or classifying the attrition-milled iron powder or the disc-milled high carbon iron powder for fine particles having an average size of 45 mm or less to obtain the metallic iron powder, wherein 90% of the fine particles having a particle size below 20 mm. In still a further embodiment, the process further comprises, screening, sieving or classifying the attrition-milled iron powder or the disc-milled high carbon iron powder for fine particles having an average size of 10 mm or less to obtain the metallic iron powder, wherein 90% of the fine particles having a particle size below 10 mm. In yet another embodiment the metallic iron powder comprises, in weight percentage, between about 0.0001 and about 4.3 C. In an embodiment, the metallic iron powder obtained has an angle of repose of between about 40 and about 50 degrees. In still another embodiment, the metallic iron powder obtained has an apparent density of between about 1.5 and about 2.5 g/cc. In yet another embodiment, the metallic iron powder obtained has a tap density of between about 3.0 and about 4.5 g/cc.

According to a third aspect, the present disclosure provides a metallic iron powder obtained by the process described herein.

According to a fourth aspect, the present disclosure provides a process for making a sponge like iron powder. Broadly, the process comprises (a) combining the metallic iron described herein with a fine iron oxide material to provide a first mixture; and (b) annealing the first mixture to cause an decarburization and agglomeration to provide the sponge-like iron powder. In an embodiment, the process further comprises (c) crushing and/or milling the sponge-like iron powder.

According to a fifth aspect, the present disclosure provides a sponge-like iron powder obtainable or obtained by the process described herein. In an embodiment, the sponge-like iron powder has an apparent density between about 1.0 and 2.5 g/cc. In yet another embodiment, the sponge-like iron powder has up to about 4.3 C. In additional embodiments, the sponge-like iron powder has between about 0.05 and about 3.5 C. BRIEF DESCRIPTION OF THE DRAWINGS

Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration, a preferred embodiment thereof, and in which:

Figure 1 provides an embodiment of a process for making the metallic iron powder of the present disclosure.

Figures 2A to 2E provide electronic micrographs of (Fig. 2A) an iron carbonyl powder, (Fig. 2B) an embodiment of the metallic iron powder annealed, (Fig. 2C) an embodiment of the metallic iron powder as-attrition milled, (Fig. 2D) an embodiment of a typical water atomized iron powder after annealing and (Fig. 2E) an embodiment of the feed material obtained by water atomization. For each of the micrographs, magnification is X2,000 and scale bar is 10 mm except for micrograph E where magnification is X1 ,000 and scale bar is 10 mm.

Figure 3 provides a comparison of the particles size distribution (%) in function of particles size diameter (mm) for an iron carbonyl powder , an embodiment of the metallic iron powder (·) and an embodiment of a typical powder obtained by water atomisation (¨).

Figure 4 provides the viscosity (in Pa s) in function of the shear rate (1/s) for the water atomized fine iron powder and the iron carbonyl powder . Results are

shown for tests conducted at 70°C , 80°C and 90°C for powders

containing 50% solids loading.

Figures 5A to 5C provide a microscopic view (100X) of Sample 1 (carbonyl iron) (Fig. 5A) Sample 15 (fine iron powder as-attrition milled) and (Fig. 5B) and Sample 16 (fine iron powder as-attrition milled) (Fig. 5C) iron powder.

Figure 6 provides the sintered density (g/cm ³ ) in function of the C/O ratio before sintering. Results are shown for sintering temperatures of 1225°C and 1270°C.

Figure 7 provides the annealed % of C in function of the annealing temperature (°C). Results are shown for different attrition milled powders having C/O ratios of 0.428 , 0.514

, 0.720 , 1.283 , and 1.302 .

Figures 8A and 8B provide micrographs of the sponge-liked material obtained. (Fig. 8A) Magnification 100X, scale bar 20 mm. (Fig. 8B) Magnification 500X, scale bar 20 mm.

DETAILED DESCRIPTION

The present disclosure provides a metallic iron powder. The metallic iron powder comprises fine particles comprising C (at a weight percentage between about 0.0001 % and about 4.3%), optionally O (up to about 10%), optionally ferro-alloying elements and the balance being Fe and unavoidable impurities. In some embodiments, the metallic iron powder excludes ferro-alloying elements. The metallic iron powder can comprise, in weight percent, at least about 0.0001 , 0.001 , 0.01 , 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 or 4.2 C. The metallic iron powder can comprise, in weight percent, no more than about 4.3, 4.2,

4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0,

1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1 , 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1 or 0.001 C. In yet another embodiment, the metallic iron powder can comprising, in weight percentage between about 0.0001 , 0.001 , 0.01 , 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3,

1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4,

3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 or 4.2 and about 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.2,

3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1 ,

1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1 or 0.001 C.

In some embodiments, the metallic iron powder can comprise up to about 10.0 O and, in some additional embodiments, the metallic iron powder can comprise between about 0.1 and about 10.0 O (for example when the powder is an non-annealed form, e.g., when the powder has not been submitted to an annealing step) or between about 0.01 to 2.0 O (for example when the powder is in an annealed form, e.g., when the powder has been submitted to an annealing step). The metallic iron powder can comprise, in weight percent, at least about 0.01 , 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.090, 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 3.0. 4.0, 5.0, 6.0, 7.0, 8.0, 9.0 O or more. The metallic iron powder can comprise, in weight percent, no more than about 9.0, 8.0, 7.0, 6.0, 5.0, 4.0, 3.0, 2.0, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1 , 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02 O or less. In yet another embodiment, the metallic iron powder can comprise, in weight percentage between about 0.01 , 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.090, 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 3.0. 4.0, 5.0, 6.0, 7.0, 8.0, 9.0 O and about 9.0, 8.0, 7.0, 6.0, 5.0, 4.0, 3.0, 2.0, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1 , 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02 O. Impurities, e.g., trace elements that are inevitably present but were not intentionally included, can be present in the metallic iron powder. In some embodiments, each impurity contributes to less than 0.5, 0.4, 0.3, 0.2 or 0.1 of total weight of the metallic iron powder.

The particles of the metallic iron powder are considered to be“fine” because the majority of the particles (e.g., 50%, 60%, 70%, 80%, 90% or more) have a particle size equal to or below about 45 mm . In some embodiments, the fine particles correspond to the -325 mesh fraction (e.g. , below 44 mm). In some embodiments, the majority (e.g., 50%, 60%, 70%, 80%, 90% or more) of the fine particles have a particle size equal to or below about 20 mm. In yet another embodiment, the majority (e.g., 50%, 60%, 70%, 80%, 90% or more) of the fine particles have a particle size equal to or higher than 1 mm. In some specific embodiments, the majority (e.g., 50%, 60%, 70%, 80%, 90% or more) of the fine particles have a particle size between about 1 and about 45 mm . In some additional specific embodiments, the majority ( e.g ., 50%, 60%, 70%, 80%, 90% or more) of the fine particles have a particle size between about 1 and about 20 mm. In some additional specific embodiments, the majority (e.g. , 50%, 60%, 70%, 80%, 90% or more) of the fine particles have a particle size between about 1 and about 10 mm.

In some embodiments, the fine particles of the metallic iron powder have a D ₅₀ size distribution of at least about 5 mm and/or of no more than 25 mm (such as, for example, a D ₅₀ size distribution of between about 5 mm and/or about 25 mm or between about 5 mm to 15 mm). The D ₅₀ size distribution is the value of the particle diameter at 50% in the cumulative distribution based on a volume basis, i.e. 50% of the particles are larger/smaller than the D ₅₀ . In some embodiments, the fine particles of the metallic iron powder have a D ₅₀ size distribution of at least about 5 mm and/or of no more than 25 mm (such as, for example, a D ₅₀ size distribution of between about 5 mm and/or about 20 mm). For example, the fine particles of the metallic iron powder have a D ₅₀ size distribution of at least about 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17, 18 or 19 mm. In yet another example, the fine particles of the metallic iron powder have a D ₅₀ size distribution of no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 1 1 , 10, 9, 8, 7, or 6 mm. In yet another example, the fine particles of the metallic iron powder have a D ₅₀ size distribution between about 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17, 18 or 19 and about 20, 19, 18, 17, 16, 15, 14, 13, 12, 1 1 , 10, 9, 8, 7, or 6 mm.

The fine particles of the metallic iron powder are not necessarily spherical and/or smooth, as shown in Figure 2B and 2C. The fine particles of the metallic powder can have, in one embodiment, an angle of repose of at least about 40 and/or no more than about 50 degrees (such as, for example, an angle of repose of between about 30 and about 60). For example, the fine particles of the metallic powder can have an angle of repose of at least about 40, 41 , 42, 43, 44, 45, 46, 47, 48 or 49 degrees. In yet another example, the fine particles of the metallic powder can have an angle of repose of no more than about 50, 49, 48, 47, 46, 45, 44, 43, 42 or 41 degrees. In still another example, the fine particles of the metallic powder can have an angle of repose between about 40, 41 , 42, 43, 44, 45, 46, 47, 48 or 49 and about 50, 49, 48, 47, 46, 45, 44, 43, 42 or 41 degrees. In some embodiments, the fine particles of the metallic powder can have an angle of repose higher than 45.

The fine particles of the metallic iron powder can have an apparent density of at least about 1.5 and/or no more than about 3.5 g/cc (such as, for example, an apparent density between about 1.5 and 3.0 g/cc). For example, the fine particles of the metallic iron powder can have an apparent density of at least about 1.5, 1.6, 1.7, 1.8, 1.9. 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3 or 3.4 g/cc. In another example, the fine particles of the metallic iron powder can have an apparent density of no more than about 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5., 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7 or 1.6 g/cc. In still a further example, the fine particles of the metallic iron powder can have an apparent density between about 1.5, 1.6, 1.7, 1.8, 1.9. 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3 or 3.4 and about 3.5, 3.4,

3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5., 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7 or 1.6 g/cc.

The term“tap density” as used herein means the ratio of the mass of the powder to the volume occupied by the powder after it has been tapped for a defined period of time. The fine particles of the metallic iron powder can have tap density of at least about 3.0 and/or no more than about 4.5 g/cc (such as, for example, a tap density between about 3.0 and 4.0 g/cc or between about

4.5 g/cc). For example, the fine particles of the metallic iron powder can have a tap density of at least about 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 , 4.2, 4.3, 4.4 or 4.5 g/cc. In another example, the fine particles of the metallic iron powder can have a tap density of no more than about 4.5, 4.4, 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2 or 3.1 g/cc. In still a further example, the fine particles of the metallic iron powder can have a tap density between about 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 , 4.2, 4.3, 4.4 or 4.5 and about 4.5,

4.4, 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2 or 3.1 g/cc.

The fine particles of the metallic iron powder can have a length to diameter ratio (e.g., a shape factor) lower than 10. In some embodiments, the fine particles of the metallic iron powder have a length to diameter ratio equal to or lower than 9, 8, 7, 6, 5, 4, 3 or 2. In a specific embodiment, the fine particles of the metallic iron powder have a near-to-spherical shape and a length to diameter ratio equal to or lower than 2.0. 2.9, 1.8, 1.7, 1.6 or 1.5. In another specific embodiment, the fine particles of the metallic iron powder have a near-to-spherical shape and a length to diameter ratio between about 1.0 and about 2.0.

The present disclosure thus provides fine particles of the metallic iron powder having at least one D ₅₀ size distribution, an angle of repose, an apparent density, a tap density and/or a shape factor characteristic as described herein. In some embodiments, the particles of the metallic iron powder have D ₅₀ size distribution which differs from the particles of carbonyl iron powder (typically being between about 4 and 8 pm) or a standard water atomized powder (typically being between 75 and 125 pm). In some embodiments, the particles of the metallic iron powder have an angle of repose which differs from the particles of carbonyl iron powder (typically being between about 50 and 55) or a standard water atomized powder (typically being between 35 and 45). In some embodiments, the particles of the metallic iron powder have an apparent density which differs from the particles of carbonyl iron powder (typically being between about

2.5 and 3.5 g/cc) or a standard water atomized powder (typically being around 2.5 and 3 g/cc). In some embodiments, the particles of the metallic iron powder have a tap density which differs from the particles of carbonyl iron powder (typically being between about 3.5 and 4.5 g/cc) or a standard water atomized powder (typically being around 3.5 g/cc).

The metallic iron powder can have a viscosity, at a temperature between 70 to 90°C, of less than 20, 10, 5 or 1 Pa·s at a shear rate of 100 s ^-1 when measured in a binder formulation having about 47 to 53 % solid loading, about 43 to 48 % paraffin wax, between about 2.8 to 3.2 % beeswax, between about 0.9 to 1.1 % stearic acid, and between 0.45 to 0.55 % ethylene vinyl acetate. In some embodiments, the binder formulation of less than 20, 10, 5 or 1 Pa s at a shear rate of 100 s ^-1 may comprise 50 % solid loading, 45.5 % paraffin wax, 3 % beeswax, 1 % stearic acid, and 0.5 % ethylene vinyl acetate.

Once formed, the metallic iron powder of the present disclosure can be used in various applications including, but not limited to metal injection molding (MIM), chemical cementation (mining), environmental remediation, diamond tools as well as hard metal binders, magnetic applications in ferro-fluids, magnetic signature, oxygen absorption, air-activated heater, friction parts, sintering aid in powder metallurgy and/or fuel applications. In one example, MIM may be used with a solids loading of up to 60% with the fine metallic iron powder.

In some specific embodiments, the metallic iron powder also includes some ferro-alloying elements which have been added (i) prior to the atomization of the liquid high carbon iron (e.g., for example by adding the ferro-alloying elements to the liquid high carbon iron composition prior to atomization) or (ii) after the metallic iron powder has been formed. Such ferro-alloying elements include, but are not limited to, Cr, Mo, Mn, Ni, Ti, W, P, B, V and/or Si, and can be used to create low alloy steels. In a specific embodiment, the ferro-alloying elements include, but are not limited to, Cr, Mo, Mn and/or Si, and can be used to create low alloy steels. In some embodiments, the weight percentage of the total ferro-alloying elements can be between about 0.1 to about 4.0 (when compared to the total weight of the liquid high carbon composition, the solid high carbon composition or the metallic iron powder). For example, the liquid high carbon composition, the solid high carbon composition or the metallic iron powder can include at least about 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9. 3.0, 3.1 , 3.2, 3.3., 3.4, 3.5, 3.6, 3.7, 3.8 or 3.9 of the total ferro-alloying element. In another example, the liquid high carbon composition, the solid high carbon composition or the metallic iron powder can include no more than 4.0, 3.9, 3.8., 3.7,

3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1 , 1.0, 0.9, 0.8, 0.7 or 0.6 of the total ferro-alloying element. In still a further example, the liquid high carbon composition, the solid high carbon composition or the metallic iron powder can include between about 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2,

1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9. 3.0, 3.1 , 3.2, 3.3.,

3.4, 3.5, 3.6, 3.7, 3.8 or 3.9 and about 4.0, 3.9, 3.8., 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9, 2.8,

2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1 , 1.0, 0.9, 0.8, 0.7 or 0.6 of the total ferro-alloying element. In some embodiment, the weight percentage of the total ferro-alloying elements can be between about 0.5 to about 1.0 (when compared to the total weight of the liquid high carbon composition, the solid high carbon composition or the metallic iron powder). For example, the liquid high carbon composition, the solid high carbon composition or the metallic iron powder can include at least about 0.5, 0.6, 0.7, 0.8 or 0.9 of the total ferro-alloying element. In another example, the liquid high carbon composition, the solid high carbon composition or the metallic iron powder can include no more than 1.0, 0.9, 0.8, 0.7 or 0.6 of the total one ferro-alloying element. In still a further example, the liquid high carbon composition, the solid high carbon composition or the metallic iron powder can include between about 0.5, 0.6, 0.7, 0.8 or 0.9 and about 1.0, 0.9, 0.8, 0.7 or 0.6 of the total ferro-alloying element.

In some additional embodiments, the metallic iron powder can be submitted to a heat treatment (as indicated below) to produce low apparent density sponge-like powders (including alloyed sponges). In some embodiments, the apparent density of the sponge-like powders is between about 1.0 and 2.5 g/cc. As it is known in the art, the ability to form low apparent density spongelike powders (e.g., the reactivity of the powder to form a sponge-like material) is influenced by the powder specific surface and particles shape, the degree of carbon and oxygen reduction as well as the duration of the thermal treatment. As such, the person skilled in the art would be able to select the appropriate powder and adjust the heat treatment parameters to create partial bonding between the fine particles of the metallic iron powder.

The present disclosure also provides a process for making the metallic iron powder. An embodiment of this process is shown in Figure 1. The process comprises a step of high energy milling to reduce the size of the feed. High energy milling that can be used include, without limitation, impact milling, jet milling, attrition milling and high-energy ball milling. In some embodiments, the process includes a step of high-energy milling such as attrition milling. High- energy milling is shown as step 050 of Figure 1. Attrition milling step comprises submitting a feed, in combination with a milling medium, to attrition milling to provide mechanical milling, e.g. , to reduce the size of the particles of the feed. High-energy milling step 050 is not intended to provide mechanical alloying and as such, it excludes providing ferro-alloying elements during the milling.

High-energy milling step 050 can be conducted in dry or wet conditions (using, for example, an organic solvent). In some embodiments, the attrition milling step 050 is conducted under dry conditions and includes the use of a dry milling medium. High-energy milling step 050 can be a batch or a continuous process. In some embodiments, high-energy milling 050 is attrition milling step and can be conducted under inert gas protection.

The milling medium used in high-energy milling such as attrition milling step 050 can comprise a plurality of media such as balls, rods, beads that can be used to grind and the particles of the feed. The milling medium is selected to have a have a higher strength and hardness than the overall feed. For example, the milling medium has at least a mechanical hardness higher than the material to be milled (e.g. , the feed) to prevent contamination and premature wear of the milling medium. In some embodiments, the milling medium is high carbon steel balls with an apparent hardness in the range of 60-62 HRC (e.g., SAE 1065 - through hardened) to withstand the high kinetic energy process.

The feed consists essentially of a solid high carbon iron composition. The solid high carbon iron composition is metallic and comprises C (between about 0.77 and 6.67 weight percent), optionally O (between about 0.1 and about 10 weight percent, and is some additional embodiments between about 0.1 and about 4.0 weight percent), optionally ferro-alloying elements (as indicated above) and the balance being Fe and unavoidable impurities. In some embodiments, the solid high carbon iron composition excludes ferro-alloying elements. In some embodiments, the solid high carbon iron composition can include inclusions which may have formed during the iron-making process. The solid high carbon iron composition can comprise, in weight percent, at least about 0.77, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,

2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 ,

4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1 , 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9. 6.0, 6.1 , 6.2,

6.3, 6.4, 6.5 or 6.6 C. The solid high carbon iron composition can comprise, in weight percent, no more than about 6.67, 6.6, 6.5, 6.4, 6.3, 6.2, 6.1 , 6.0, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, 5.3, 5.2, 5.1 , 5.0, 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1 , 1.0, 0.9 or 0.8 C. In yet another embodiment, the solid high carbon iron composition can comprise, in weight percentage between about 0.77, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0,

4.1 , 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1 , 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9. 6.0, 6.1 ,

6.2, 6.3, 6.4, 6.5 or 6.6 and about 6.67, 6.6, 6.5, 6.4, 6.3, 6.2, 6.1 , 6.0, 5.9, 5.8, 5.7, 5.6, 5.5,

5.4, 5.3, 5.2, 5.1 , 5.0, 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4,

3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3,

1.2, 1.1 , 1.0, 0.9 or 0.8 C. In some embodiment, the solid high carbon iron composition can comprise between about 2.0 to about 4.3 C. For example, the solid high carbon iron composition can comprise, in weight percentage, at least about 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6,

2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 or 4.2 C. In another embodiment, the solid high carbon iron composition can comprise, in weight percentage no more than about 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6,

2.5, 2.4, 2.3, 2.2 or 2.1 C. In still another embodiment, the solid high carbon iron composition can comprise, in weight percentage, between about 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 , 4.2 and about 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8,

3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2 or 2.1 C. In yet another embodiment, the solid high carbon iron composition comprises, in weight percentage, about 3.0 C. The solid high carbon iron composition of the present disclosure comprises up to about 10 O (such as, for example, between about 0.1 and about 10 O). In an embodiment, the solid high carbon iron composition comprises at least about 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,

1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 ,

3.2, 3, .3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 , 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1 , 5.2,

5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1 , 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1 , 7.2, 7.3,

7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1 , 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1 , 9.2, 9.3, 9.4,

9.5, 9.6, 9.7, 9.8 or 9.9 O. In another embodiment, the solid high carbon iron composition comprises no more than 9.9, 9.8, 9.7, 9.6, 9.7, 9.6, 9.5, 9.4, 9.3, 9.2, 9.1 , 9.0, 8.9, 8.8, 8.7, 8.6,

8.5, 8.4, 8.3, 8.2, 8.1 , 8.0, 7.9, 7.8, 7.7, 7.6, 7.5, 7.4, 7., 7.2, 7.1 , 7.0, 6.9, 6.8, 6.7, 6.6, 6.5, 6.4,

6.3, 6.2, 6.1 , 6.0, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, 5.3, 5.2, 5.1 , 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2,

4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9. 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 ,

2.0, 1.9, 1.8, 1.7., 1.6., 1.5, 1.4, 1.3, 1.2, 1.1 , 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3 or 0.2 O. In yet another embodiment, the solid high carbon iron composition comprises between about 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3,

2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3, .3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 , 4.2, 4.3, 4.4,

4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1 , 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1 , 6.2, 6.3, 6.4, 6.5,

6.6, 6.7, 6.8, 6.9, 7.0, 7.1 , 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1 , 8.2, 8.3, 8.4, 8.5, 8.6,

8.7, 8.8, 8.9, 9.0, 9.1 , 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8 or 9.9 and about 9.9, 9.8, 9.7, 9.6, 9.7, 9.6,

9.5, 9.4, 9.3, 9.2, 9.1 , 9.0, 8.9, 8.8, 8.7, 8.6, 8.5, 8.4, 8.3, 8.2, 8.1 , 8.0, 7.9, 7.8, 7.7, 7.6, 7.5,

7.4, 7., 7.2, 7.1 , 7.0, 6.9, 6.8, 6.7, 6.6, 6.5, 6.4, 6.3, 6.2, 6.1 , 6.0, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, 5.3,

5.2, 5.1 , 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9. 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7., 1.6., 1.5, 1.4, 1.3, 1.2, 1.1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3 or 0.2 O.

In some embodiments, a ratio of the concentration of C to O (C/O) can be controlled to adjust the carbon content in the solid high carbon iron composition. For example, the C/O ratio can be controlled by the screening process and/or with additions of C and O such as graphite or oxidized powder. In another example, the C/O ratio can be controlled by the smaller particles (such as less than 10 mm). Maintaining the ratio C/O between about 0 and about 3.5, between about 0.5 and about 2.0, 0.6 and about 1.9, between about 0.5 and about 1.8, between about 0.5 and about 1.7, between about 0.5 and about 1.6, between about 0.5 and about 1.5, between about 0.6 and about 1.4, between about 0.7 and about 1.3, between about 0.8 and about 1.2, between about 0.9 and about 1.1 or about 1.0 can improve, in some embodiments, the density of the powder as shown in Figure 6.

The solid high carbon iron composition of the feed can comprise cementite Fe ₃ C. In an embodiment, the solid high carbon iron composition can be an hypereutectoid steel powder presenting brittle carbide phases in the grain boundary region (e.g., a pearlite (Fe ₃ C + a iron) matrix comprising intergranular cementite Fe ₃ C (e.g., 0.77-2.11 %). When the weight percentage of C in the solid high carbon iron composition is between about 2 to about 4.3, the solid high carbon iron composition can be an hypoeutectic cast iron comprising cementite, pearlite (Fe ₃ C + a iron) and transformed ledeburite phases. When the weight ratio of C in the solid high carbon iron composition is between about 4.3 and about 6.67, the solid high carbon iron composition can be an hypereutectic cast iron comprising cementite Fe ₃ C and ledeburite phases.

In an embodiment, the solid high carbon iron composition is not an“iron sand” (e.g., composed mainly of Fe ₃ S0 ₄ ), an iron ore or an iron oxide. In a further embodiment the solid high carbon iron composition is free of an iron sand, an iron ore or an iron oxide at a level of O superior to 10% before annealing. In still a further embodiment, the solid high carbon iron composition is not mixed with another powder (like a Si-based powder for example) prior to or during the high- energy milling step 050. In yet another embodiment, the solid high carbon iron composition does not include a reinforcement material such as, for example, ceramic and/or a ferro-alloying element.

In the context of the present disclosure, the high-energy milling is used to reduce the particle sizes of the solid high carbon iron composition and is not intended to be used to produce a ferro-alloy or a composite material (which may include reinforcement particles such as ceramic particles) by mechanical alloying.

The coarse particles of the solid high carbon iron composition can have an average particle size between about 50 to 400 mm. In some embodiments, the coarse particles of the solid high carbon iron composition can have a particle size of at least about 50 mm, at least about 100 mm, at least about 200 mm, and in some embodiments, at least about 300 mm or higher. In some additional embodiments, the coarse particles of the solid high carbon iron composition can have a particle size between about 100 to about 200 mm. In some embodiments, the coarse particles of the solid high carbon iron composition can include particles that have a size in the mm range. In some embodiments, the coarse particles of the solid high carbon iron composition have a D ₁₀ of about 50 mm, a D ₅₀ of about 200 mm and/or a D ₉₀ of about 400 mm. In still yet another embodiment, the coarse particles of the solid high carbon iron composition have a D ₁₀ of about 50 mm, a D ₅₀ of about 200 mm and a D ₉₀ of about 400 mm. The D ₁₀ size distribution is the value of the particle diameter at 10% in the cumulative distribution based on volume and the D ₉₀ size distribution is the value of the particle diameter at 90% in the cumulative distribution based on volume.

Step 050 processes the feed/solid high carbon iron composition into a high-energy milled (e.g., attrition-milled) composition. It is understood that the size of the particles of the attrition-milled composition are smaller than those of the feed/solid high carbon iron composition.

In some embodiments, the attrition-milled composition can be directly submitted to a thermal treatment step 070. Alternatively, the attrition-milled composition can then be submitted to a screening, sieving or classifying step 060 for enriching particles having a size equal to or less than 45 mm or to a screening, sieving or classifying step 090 for enriching particles having a size equal to or less than 20 mm. Screening step 060 (which can be substituted by a sieving step or a classification step, not shown on Figure 1) can be done, for example, by removing particles having a particle size higher than 45 mm and/or selecting particles having a particle size equal to or lower than 45 mm . Screening step 090 (which can be substituted by a sieving step or a classification step, not shown on Figure 1) can be done, for example, by removing particles having a particle size higher than 20 mm and/or selecting particles having a particle size equal to or lower than 20 mm. In an optional embodiment, the process can include returning the particles having a size higher than 45 mm or 20 mm to high-energy milling step 050 for further size reduction. Additional screening, sieving or classifying steps can be performed to select or enrich particles having a size lower than 10 mm. Additional screening, sieving or classifying steps can be performed to remove particles having a size lower that 10 mm such that the particle sizes remaining are distributed between 10 mm and 45 mm . Depending on the application of the powder, the particles can be screened, sieved, or classified for particles having a size lower than about 1 1 , 12, 13, 14, 15, 16, 17, 18, 19, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38 or 39 mm. Alternatively, the screened compositions obtained from step 060 or 090 can be used directly into downstream operations.

In some embodiments, the process comprises preparing the feed. In Figure 1 , the feed preparation steps can include, without limitation, an atomizing step 010, a magnetic separation and vacuum filtration step 020, a ball milling step 030 and/or a screening, sieving or classifying step 040. The atomizing step 010 comprises submitting a liquid high carbon iron composition to water atomization under conditions so as to allow the production of an atomized high carbon iron composition. The liquid high carbon iron composition comprises C (between about 0.77 and 6.67 weight percent), optionally O (e.g., in some embodiments, up to about 4.0 weight percent or up to about 1.0 weight percent), optionally ferro-alloying elements and the balance being Fe and unavoidable impurities. In some embodiments, the liquid high carbon iron composition excludes ferro-alloying elements. The liquid high carbon iron composition can comprise, in weight percent, at least about 0.77, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,

2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 ,

4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1 , 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9. 6.0, 6.1 , 6.2,

6.3, 6.4, 6.5 or 6.6 C. The liquid high carbon iron composition can comprise, in weight percent, no more than about 6.67, 6.6, 6.5, 6.4, 6.3, 6.2, 6.1 , 6.0, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, 5.3, 5.2, 5.1 , 5.0, 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1.1 , 1.0, 0.9 or 0.8 C. In yet another embodiment, the liquid high carbon iron composition can comprise, in weight percentage between about 0.77, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 , 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1 , 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9. 6.0, 6.1 ,

6.2, 6.3, 6.4, 6.5 or 6.6 and about 6.67, 6.6, 6.5, 6.4, 6.3, 6.2, 6.1 , 6.0, 5.9, 5.8, 5.7, 5.6, 5.5,

5.4, 5.3, 5.2, 5.1 , 5.0, 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4,

3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3,

1.2, 1.1 , 1.0, 0.9 or 0.8 C. In some embodiment, the liquid high carbon iron composition can comprise between about 2.0 to about 4.3 C. For example, the liquid high carbon iron composition can comprise, in weight percentage, at least about 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6,

2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 or 4.2 C. In another embodiment, the liquid high carbon iron composition can comprise, in weight percentage no more than about 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6,

2.5, 2.4, 2.3, 2.2 or 2.1 C. In still another embodiment, the liquid high carbon iron composition can comprise, in weight percentage, between about 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 , 4.2 and about 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8,

3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2 or 2.1 C. In yet another embodiment, the liquid high carbon iron composition comprises, in weight percentage, about 3.0 C.

In some embodiments, the liquid high carbon iron composition of the present disclosure comprises up to about 1.0 O. During atomization, the powder can be oxidized. As such, after atomization, the solid high carbon iron composition can comprise up to about 10 O (such as, for example, between about 0.1 and about 10 O). In an embodiment, the solid high carbon iron composition comprises at least about 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3,

1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3, .3, 3.4,

3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 , 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1 , 5.2, 5.3, 5.4, 5.5,

5.6, 5.7, 5.8, 5.9, 6.0, 6.1 , 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1 , 7.2, 7.3, 7.4, 7.5, 7.6,

7.7, 7.8, 7.9, 8.0, 8.1 , 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1 , 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8 or 9.9 O. In another embodiment, the solid high carbon iron composition comprises no more than 10.0, 9.9, 9.8, 9.7, 9.6, 9.7, 9.6, 9.5, 9.4, 9.3, 9.2, 9.1 , 9.0, 8.9, 8.8, 8.7, 8.6, 8.5, 8.4, 8.3,

8.2, 8.1 , 8.0, 7.9, 7.8, 7.7, 7.6, 7.5, 7.4, 7., 7.2, 7.1 , 7.0, 6.9, 6.8, 6.7, 6.6, 6.5, 6.4, 6.3, 6.2, 6.1 ,

6.0, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, 5.3, 5.2, 5.1 , 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1 , 4.0, 3.9,

3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9. 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8,

1.7., 1.6., 1.5, 1.4, 1.3, 1.2, 1.1 , 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3 or 0.2 O. In yet another embodiment, the solid high carbon iron composition comprises between about 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 , 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5,

2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3, .3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 , 4.2, 4.3, 4.4, 4.5, 4.6,

4.7, 4.8, 4.9, 5.0, 5.1 , 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1 , 6.2, 6.3, 6.4, 6.5, 6.6, 6.7,

6.8, 6.9, 7.0, 7.1 , 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1 , 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8,

8.9, 9.0, 9.1 , 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8 or 9.9 and about 10.0, 9.9, 9.8, 9.7, 9.6, 9.7, 9.6,

9.5, 9.4, 9.3, 9.2, 9.1 , 9.0, 8.9, 8.8, 8.7, 8.6, 8.5, 8.4, 8.3, 8.2, 8.1 , 8.0, 7.9, 7.8, 7.7, 7.6, 7.5, 7.4, 7., 7.2, 7.1 , 7.0, 6.9, 6.8, 6.7, 6.6, 6.5, 6.4, 6.3, 6.2, 6.1 , 6.0, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, 5.3, 5.2, 5.1 , 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1 , 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1 , 3.0, 2.9. 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1 , 2.0, 1.9, 1.8, 1.7., 1.6., 1.5, 1.4, 1.3, 1.2, 1.1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3 or 0.2 O.

The atomized high carbon iron composition of the feed can comprise cementite. In an embodiment, the atomized high carbon iron composition can be an hypereutectoid steel powder presenting brittle carbide phases (e.g., a pearlite matrix comprising intergranular cementite). When the weight percentage of C in the atomized high carbon iron composition is between about 2 to about 4.3, the atomized high carbon iron composition can be an hypoeutectic cast iron comprising cementite, perlite and transformed ledeburite phases. When the weight percentage of C in the atomized high carbon iron composition is between about 4.3 and about 6.67, the atomized high carbon iron composition can be an hypereutectic cast iron comprising cementite and ledeburite phases.

In an embodiment, the atomized high carbon iron composition not mixed with another powder (like a Si-based powder for example) prior to or during the high-energy milling step 050. In yet another embodiment, the atomized high carbon iron composition is not admixed with a reinforcement material such as, for example, ceramic and/or a ferro-alloying element prior to high-energy milling step 050.

In an embodiment, once the atomized high carbon iron composition has been produced, it is not submitted to a thermal treating step prior to the high-energy milling step 050. However, in some embodiments, in order to facilitate the breakage of the particles of the atomized high carbon iron composition during the high-energy milling step, the atomized high carbon iron composition can be submitted to a heat treatment step (not shown on Figure 1) prior to the high-energy milling step. For example, when the atomized high carbon iron composition comprises martensite (due, for example, to a rapid cooling during the water atomization step), the heat treatment step can be done to convert, at least in part some of the martensite into pearlite to reduce the apparent hardness and consequently the abrasiveness of the high carbon iron composition to the high energy milling equimment. In such embodiment, the heating step should be conducted into conditions so as to minimize carbon loss of the high carbon material. The person skilled in the art is aware that selecting the appropriate atmosphere, the duration of the heat treatment step and the rate of cooling of the heat treatment step can achieve the conversion of martensite into pearlite without substantially reducing the amount of C in the atomized high carbon iron composition.

The coarse particles of the atomized high carbon iron composition can have an average particle size between about 50 to 400 mm. In some embodiments, the coarse particles of the atomized high carbon iron composition can have a particle size of at least about 50 mm, at least about 100 mm, at least about 200 mm, and in some embodiments, at least about 300 mm or higher. In some additional embodiments, the coarse particles of the atomized high carbon iron composition can have a particle size between about 100 to about 200 mm. In some embodiments, the coarse particles of the atomized high carbon iron composition can include particles have a size in the mm range. In some embodiments, the coarse particles of the solid high carbon iron composition have a D ₁₀ of about 50 mm, a D ₅₀ of about 200 mm and/or a D ₉₀ of about 400 mm. In still yet another embodiment, the coarse particles of the solid high carbon iron composition have a D ₁₀ of about 50 mm, a D ₅₀ of about 200 mm and a D ₉₀ of about 400 mm.

The atomized high carbon iron composition can be submitted directly as a feed to high-energy milling step 050 or can be further processed before being used as a feed for high-energy milling step 050. For example, the atomized high carbon iron composition can be submitted to a magnetic separation and vacuum filtration step 020 to enrich the atomized high carbon iron composition in magnetic particles (and provide a separated high carbon iron composition). Alternatively or in combination, the atomized high carbon iron composition or the separated high carbon iron composition can be submitted to a step of ball milling 030 to reduce the particle size prior to the high-energy milling step 050 and provide a ball-milled composition. Ball milling step 030 can be advantageous to reduce the attrition milling time and/or intensity. In an embodiment, once the separated composition or the ball-milled composition has been produced, they are not submitted to a thermal treating step prior to the high-energy milling step 050. Alternatively, the separated composition or the ball-milled composition can be submitted to a heat treatment step, as described above, to reduce the abrasiveness without substantially reducing the C content of the material.

When ball-milling step 030 is performed, the ball-milled composition can be used as a feed and be submitting directly to high-energy milling step 050. However, in some embodiments, the ball- milled composition can be submitted to a screening, sieving or classifying step 040 for enriching particles having a size equal to or less than 45 mm, 20 mm or 10 mm. In an optional embodiment, the process can include returning the particles having a size higher than 45 mm, 20 mm or 10 mm to ball milling step 030 for further size reduction. This can be done, for example, by removing particles having a particle size higher than 45 mm, 20 mm or 10 mm and/or selecting particles having a particle size equal to or lower than 45 mm , 20 mm or 10 mm. Depending on the application of the powder, the particles having a size higher than about 1 1 , 12, 13, 14, 15, 16, 17, 18, 19, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38 or 39 mm can be removed.

The metallic iron powder can be obtained after screening, sieving or classifying step 060. The metallic iron powder obtained directly after step 060 can be used in downstream applications. However, the metallic iron powder can be further treated prior to its intended end use.

In some embodiments, the metallic iron powder can be submitted to a thermal treatment step 070 sometimes referred to as an annealing step, and can be a decarburization and reducing thermal treatment, to provide a heat-treated composition. In thermal treatment step 070, the metallic iron powder can be treated at a temperature between about 400 to 1 000°C. In an embodiment, the thermal treatment step 070 is conducted at a temperature of at least about 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 725, 750, 775, 800, 825, 850, 875, 900, 925, 950 or 975°C. In another embodiment, the thermal treatment step 070 is conducted at a temperature of no more than about 1 000, 975, 950, 925, 900, 875, 850, 825, 800, 775, 750, 725, 700, 675, 650, 625, 600, 575, 550, 525, 500, 475, 450 or 425°C. In still a further embodiment, the thermal treatment step 070 is conducted at a temperature of between about 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 725, 750, 775, 800, 825, 850, 875, 900, 925, 950 or 975°C or about 1 ,000, 975, 950, 925, 900, 875, 850, 825, 800, 775, 750, 725, 700, 675, 650, 625, 600, 575, 550, 525, 500, 475, 450 or 425°C. In yet another embodiment, the thermal treatment step 070 is conducted at a temperature of about 850°C. In some embodiments, the thermal treatment step is conducted at a temperature which preserves the particle size distribution of the metallic iron powder. The thermal treatment step 070 can be conducted for a period of 5 min to 48 hours, in some embodiments from 1 to 12 hours and, in some further embodiments, between 1.5 to 3.0 hours. The duration of the treatment in the“hot zone” (e.g., the highest temperature reached during the thermal treatment), can be at least about 10 min and at most about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 min. The heat treatment step 070 can be conducted under a reducing environment, such as a gas mixture comprising H ₂ , Ar, CO, N ₂ or cracked ammonia. In one example, the thermal treatment step is an annealing with rotary annealing such as a Rotary Kiln to reduce particle agglomeration, in a nitrogen atmosphere containing up to 4% hydrogen (lower explosive limit (LEL)). In one embodiment, the distribution of oxygen in an untreated metallic iron powder is skewed to the fine fraction of the particle size distribution. By size selection such as screening or classification, the carbon:oxygen ratio in the untreated metallic powder can be varied over a wide range. After annealing, the residual carbon content in the powder was found to vary between 0.002 and 1.9 wt%. The coarser the powder, the lower the oxygen content in the annealed powder.

After the thermal treatment step 070, and depending on the conditions used during the thermal treatment, the heat-treated composition can produce a“cake” (especially when a continuous belt furnace is used to perform the heat treatment 070) which can be de-agglomerated using a further milling step, such as disc milling step 080, to provide a disc-milled composition. The disc- milled composition as be used directly into downstream applications or can be submitted to screening, sieving or classifying step 090. Step 090 can be done, for example, by removing particles having a particle size higher than 45 mm, 20 mm or 10 mm and/or selecting particles having a particle size equal to or lower than 20 mm or 10 mm. The screened composition obtained from step 090 can be used directly into downstream operations. In some embodiments, disc milling is not necessary if the heat treatment step 070 does not produce a“cake”. For example, when a fluid bed or a rotary kiln is used to provide the heat treatment step 070, disc milling step 080 may not be necessary. As such, the heat treated composition can be used in downstream operations or be screened at step 090.

In some embodiments, the thermally treated metallic iron powder can be used to provide a sponge-like material in which the particles agglomerate and are left in an agglomerated state. Such processes could include, but are not limited to, the addition of a fine iron oxide material to the fine iron powder in order to further reduce the apparent density and to facilitate the removal of carbon by balancing the carbon:oxygen ratio in the feed material. In some embodiments, the sponge-like material can be used directly in downstream operations.

The present disclosure thus provides a process for making a sponge-like iron powder. Initially, a mixture comprising the metallic iron powder described herein and a fine iron oxide material is prepared. Various weight ratios between the metallic iron powder and fine iron oxide can be used, for example from about 3:1 to about 1 :1. The initial mixture can be supplemented (for example with graphite) to adjust the carbon to oxygen ratio prior to the annealing step. In some embodiments, the carbon to oxygen weight ratio of the initial mixture is between about 1 :2 to about 2:3.

Once the initial mixture is prepared, it is submitted to an annealing step to decarburize and agglomerate the particles to form a sponge-like material. In some embodiments, agglomerates are considered to be present when an increase in the D ₉₀ to between 100 to 320 microns is observed in the annealed product (when compared to the initial mixture). The annealing step can be conducted for a period of 5 min to 48 hours, in some embodiments from 1 to 12 hours and, in some further embodiments, between 1.5 to 3.0 hours. The duration of the treatment in the“hot zone” (e.g., the highest temperature reached during the thermal treatment), can be at least about 10 min and at most about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 min. The annealing step can be conducted under a reducing environment, such as a gas mixture comprising H ₂ , Ar, CO, N ₂ or cracked ammonia. In some embodiments, the process includes a single annealing step (e.g. , first pass) and excludes further annealing step to provide the sponge-like iron powder.

In some embodiments, the process also includes a step of crushing and/or milling (for example disc milling) the sponge-like iron powder to control, amongst other things, the degree of agglomeration after the annealing step.

The person of ordinary skill in the art will recognize that the degree of agglomeration and consequently the apparent density of the sponge-like material can be controlled by appropriate choice of metallic iron powder and fine iron oxide ratio, the annealing temperature, time and atmosphere, as well as the crushing and milling conditions (if any) chosen to process the sponge-like iron powder. The sponge-like iron powder obtained by the process described herein can have a wide range of apparent densities. For example, the sponge-like iron powder described herein can have an apparent density between about 1.0 and about 2.5 g/cc. It is possible to use the process to obtain sponge-like powders having a relatively low apparent density value, for example between about 1.3 to 1.5 g/cc (e.g., comparable similar to the low apparent density a sponge Fe powders made by Direct Reduction of iron ore (DRI)). In some embodiments, the sponge-like iron powder described herein has between about 0.07 and 7.5 C. In additional embodiments, the sponge like powder described herein has between about 0.08 to 2.8 O.

The present invention will be more readily understood by referring to the following examples which are given to illustrate the invention rather than to limit its scope.

EXAMPLE

Metallic (water atomized fine) iron powder manufacturing process was performed with molten iron. The molten iron contained approximately 3 wt% carbon was low pressure water atomized to generate coarse iron-carbon powder of an average particle size around 300 micron. The dried powder was ground in an attritor mill with carbon steel media under a nitrogen cover gas until roughly 80 to 90% of the powder passed a 325 mesh screen as measured on a laboratory Ro-Tap screener. The -325 mesh powder contained approximately 4% oxygen. Some of the powder was further screened to 635 mesh (20 micron) and 1200 mesh (10 micron) using high energy screening equimment. The -20 micron fraction oxygen content was approximately 6% and the -10 micron fraction oxygen content was between 7 to 8%. A portion of the screened fractions of powder was thermally treated in a continuous belt furnace between 650 and 950 °C to decarburize the powder and reduce oxygen content. The sinter cake was subsequently disc milled to recover the original particle size distribution. Oxygen and carbon contents could be controlled by varying residence time, temperature and furnace atmosphere, namely the nitrogen:hydrogen ratio. The powder carbon and oxygen concentrations are shown in Table 1. The cake thickness was 1.25 in for all samples. The belt speed was between 3 in/min to 6 in/min, equivalent to a residence time of 30 to 60 min in the high heat section of the furnace.

Table 1. Summary of the concentration concentrations of carbon and oxygen for 40 samples testes (#1 - #40), the temperature of annealing, the particle fraction and particle size distribution (D10, D50, and D90). Chemical composition was measured by LECO. Particle size is provided in mm.

The water atomized fine iron powder was characterized and compared to a commercially available iron carbonyl powder and a standard water atomized iron powder. As shown by electron microscopy, the water atomized fine iron powder is larger and of more irregular shape than the iron carbonyl powder (compare Figure 2A with Figure 2B (annealed) and Figure 2C (as-attrition milled)), yet smaller and more spherical than the standard water atomized iron powder (compare Figures 2B and 2D). Table 2 provides additional characteristics of the water atomized fine iron powder. Figure 3 provides a particle size distribution of the water atomized fine iron powder (as determined by Helos instrument by Sympatec).

Table 2. Comparison of the characteristics of an iron carbonyl powder, the water atomized fine iron powder and the standard water atomized iron powder.

The rheological properties of the carbonyl iron powder and the water atomized fine iron powder were determined using a 50-55% solids loading (binder formulation = 91 % paraffin wax, 6% beeswax, 2% stearic acid and 1 % ethylene vinyl acetate) at an injection temperature between 70 to 90°C. The results are shown in Figure 4. A shear rate of 100 s ^-1 represents a typical value for low pressure injection molding (LPIM) injection and at which the measured viscosities were below the maximum limit (< 20 Pa ·s. A shear thinning behavior i.e. a decrease in viscosity is expected during the injection stage. A moderate viscosity at low shear rate is beneficial to maintain the shape after the injection of feedstock.

Sintering behaviour of the iron carbonyl and the water atomized fine iron loose powders was determined in a H ₂ (100%) atmosphere, at a maximal temperature of 1225-1270°C for 90 minutes. The sintering furnace was heated to 1 150°C at a heating rate of 5°C/min and then heated to 1250°C at a heating rate of 2°C/min. The characteristics of the sintered powder are shown in Table 3. A microscopic view of the resulting sintered powders is provided in Figure 5. The specific surface area of the powder is the main driving parameter for loose powder sintering. Results for the sintered density are shown in Figure 6.

Table 3. Characteristics of sintered iron carbonyl powder, annealed fine iron powder and fine iron powder as-attrition milled.

The impact of annealing temperature on the final powder chemical composition and particle size distribution was investigated with certain samples of Table 1. The results are shown in Figure 7. As can be seen in Figure 7, the annealed % of C increased with the increasing C/O ratio in the attrition milled powder.

Fine Fe powder was determined to be suitable as a diamond binder (data not shown). The fine metallic iron powder was granulated with other metal powders such as bronze and Ni and industrial grade diamonds, then cold pressed into rectangular 40 x 12 mm green specimens in a rigid carbide-lined die at 250 MPa. The green specimens were sintered in a laboratory tube furnace for 29 minutes at 933°C in hydrogen. The laboratory furnace sintering cycle and the industrial, conveyor belt furnace sintering cycle are compared in Fig. 8. The control was a carbonyl Fe powder (CIP) (D ₁₀ = 3.19, D ₅₀ = 5.34, D ₉₀ = 13.71 , C % = 0.03). Sintered density (8.05 g/cm3), Transverse Rupture Strength (100 MPa) and Apparent Hardness (100 HRB) were similar to the CIP control powder.

A thermal treatment step by rotary annealing was tested with a Rotary Kiln. The Rotary Kiln demonstrated a reduction in particle agglomeration, in a nitrogen atmosphere containing up to 4% hydrogen (lower explosive limit (LEL)). Four samples were tested, the experimental conditions and results for each sample are shown in the Table 4.

Rotary kiln annealing was performed using the -45 μm of as-attrition milled powder and annealing these in a rotary kiln at 760°C or 850°C for one hour. Ramp-up profile used was 10°C/min, the quartz tube was rotated at 1 ,5 RPM and the powder was cooled under nitrogen at a rate of 5°C/min. Due to the relatively high C/O, the final carbon content achieved was around 1.6% C. In order to proceed further with the C reduction, a high oxygen powder (about 20% O) was blend in at various levels (5 or 15%). As shown in Table 4, in trials 3 and 4, C levels was decreased down to 0,41 and 1 ,03% respectively while keeping a similar particle size distribution (PSD) which was the initial intent of using such annealing process.

Table 4. Results of the Rotary Kiln experiment

A sponge-like material was prepared. Mixtures of -45 micron (325 mesh) attrition-milled Fine Iron Powder (FFeP), Fine iron oxide (FFeO, nominal FeO (wustite) in composition) sieved -63 micron (230 mesh) and fine Powder Metallurgy grade graphite (Timrex PG-25) were blended and annealed in a horizontal belt furnace provided with a reducing nitrogen-hydrogen atmosphere at 1040°C, with a residence time of approximately 45 minutes at or above the temperature set point. The mixtures were chosen to cover a range of FFeP:FFeO from 3: 1 to 1 : 1 w/w%. Graphite was added in order to adjust the carbon: oxygen (C:0) ratio between 1 :2 and 2:3. The hydrogen content of the furnace atmosphere was varied between 10% H ₂ /90% N ₂ and 100% H ₂ . The annealed Fe powder mixture cake was crushed and disc milled. Residual C and O were analysed by Leco and the Apparent Density was measured for each sample.

In Table 5, the carbon and oxygen contents of the annealed powders ranged from 0.07 to 7.5 w/w% and 0.08 to 2.8 w/w% respectively, depending on the starting C:0 ratio in the powder mixture and the amount of hydrogen in the furnace atmosphere. The Apparent Density ranged from 2.3 to 1 .3 g/cm ³ as measured by Hall apparatus (MPIF Standard 04). From the micrographs (Fig. 8), a distribution of agglomerated powder and fine powder can be seen. The formation of agglomerates is indicated by the increase in the D90 to between 100 to 320 microns. The individual particles that make up the agglomerates can be seen to be non-porous, unlike sponge Fe made by reduction of iron oxide. Table 5. Information concerning the sponge-like powder trials performed and the characteristics of the sponges obtained.

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While the invention has been described in connection with specific embodiments thereof, it will be understood that the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.