Claims:We Claim:
1. A method for deoxidizing iron through reduction-annealing process, the method comprising:
mixing, an iron powder with a graphite powder to obtain an iron-graphite powder mixture;
blending, the iron-graphite powder mixture to obtain a homogenized iron-graphite powder mixture;
annealing, the homogenized iron-graphite powder mixture at a temperature range of 1000°C to 1200°C for about 1 hr to 2 hrs, wherein annealing reduces the homogenized iron-graphite powder mixture to an iron cake and deoxidizes the iron; and
cooling, the deoxidized iron cake to room temperature.

2. The method as claimed in claim 1, wherein the deoxidized iron cake is subjected to:
crushing, wherein the crushing results in reduction of the iron cake to granules of size 2 mm or less; and
milling of the granules of size 2 mm or less, wherein the milling results in reduction of the granules to iron powder of size 150 micron or less.

3. The method as claimed in claims 1 and 2, wherein the iron powder after the milling has a density of 2.55 g/cc or less.

4. The method as claimed in claims 1 to 3, wherein the iron powder has an average particle size ranging from 15 µm to 100 µm.

5. The method as claimed in claim 1, wherein the iron powder before undergoing the reduction-annealing has a composition of:
Iron – at least 98 wt%;
Carbon - 0.03 wt% to 0.08 wt%;
Oxygen - 0.4 wt% to 0.5 wt%.

6. The method as claimed in claim 1, wherein the graphite powder has a fixed carbon of at least 98wt%.

7. The method as claimed in claim 6, wherein the graphite powder in range of 0.3wt% to 0.4wt% is added to the iron powder.

8. The method as claimed in claim 1, wherein blending of iron-graphite powder mixture to form the homogenized iron-graphite powder mixture is carried out in a blender.

9. The method as claimed in claim 1, wherein the annealing is carried out in a fixed bed-type furnace.

10. The method as claimed in claim 1, wherein the annealing of homogenized iron-graphite powder is carried out in an inert atmosphere preferably in a nitrogen atmosphere.

11. The method as claimed in claim 1, wherein cooling of the annealed iron cake is carried out in an inert atmosphere preferably in a nitrogen atmosphere.

12. The method as claimed in claim 1, wherein crushing of deoxidized iron cake is carried out in a jaw crusher.

13. The method as claimed in claim 1, wherein the milling is carried out in a hammer mill.

14. The method as claimed in claim 1, wherein the oxygen concentration in the iron power after reduction-annealing processing is less than 0.3wt% preferably less than 0.2 wt%

15. Iron powder processed by a method as claimed in claim 1, comprising composition in wt% of:
Iron - at-least 98.5 wt%;
Carbon - 0.02 wt% to 0.09 wt%; and
Oxygen - 0.3 wt% or less.

Dated this 30th Day of March, 2021 NIKHIL S.
OF K&S PARTNERS
IN/PA-2127
AGENT FOR THE APPLICANT

, Description:FORM 2
THE PATENTS ACT, 1970
[39 of 1970]
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[See Section 10 and Rule 13]

TITLE: “A METHOD FOR DEOXIDIZING IRON POWDER THROUGH REDUCTION-ANNEALING PROCESS”

Name and Address of the Applicant:
TATA STEEL LIMITED, Jamshedpur, Jharkhand, India 831001.

The following specification particularly describes the nature of the invention and the manner in which it is to be performed.
TECHNICAL FIELD
Present disclosure relates in general to a field of material science and metallurgy. Particularly, but not exclusively, the present disclosure relates to processing of iron powder. Further, embodiments of the disclosure disclose a method of deoxidizing unalloyed low carbon iron powder to manufacture low oxygen iron powder while substantially preventing carburizing of the iron powders by using high purity graphite powder.

BACKGROUND OF THE DISCLOSURE
Iron powder or steel powder is produced by many commercial processes mainly: carbonyl, electrolytic, atomization (gas or water) and reduction technologies. Each method of production yields iron powders that are pure in nature albeit in varying levels. However, carbon and oxygen are major constituents in all the iron powders and are undesirable when in high percentages. Higher carbon and oxygen levels in the iron powders impairs its compressibility and sinterability properties especially, in atomized and reduced iron powders which are majorly used for powder metallurgical applications. Higher oxygen in the iron powders also leads to lower mechanical strength of the sintered components due to poor sintering and possibility of oxide inclusions. In conventional powder metallurgy, iron powders are usually ad-mixed with graphite powders in addition to alloying elements such as copper, nickel etc. These alloying elements may be in pre-alloyed form or diffusion bonded to iron powders so that the compressibility characteristics are good. Moreover, oxygen content in these iron powders would affect the final sintering behaviour in these types of systems where higher graphite additions would be required to compensate for the higher oxygen content which would escape as carbon monoxide (CO) at normal sintering temperatures (above 1000oC). Therefore, low carbon-low oxygen iron powders are highly desirable especially for powder metallurgical applications. Apart from powder metallurgy applications, such iron powders are desirable for oxygen absorption and magnetic applications also.
Conventionally, annealing of iron powders are essentially carried out to lower the initial carbon and oxygen content especially of atomized and reduced iron powder. Atomized iron powder (Gas/Water) are subjected to annealing as a final step in hydrogen rich atmosphere at high temperatures for 1-4 hrs so that, both carbon and oxygen contents are brought down within desirable levels preferably C below 0.05 wt% and O below 0.2 wt% to yield usable powders. Also, decarburization is one of the major steps especially for atomized iron powders in addition to deoxidation in annealing process. This is due to higher carbon content in atomized powder originating from the different sources of melt such as scrap metal, cast iron etc.
Several prior arts exist to deoxidize iron powder pellets as discussed below:
GB959570A discusses a method to deoxidize the iron powder by simple heating in nitrogen at 1100oC where the initial carbon content is so high that it acts a self-reducing agent. However, such method would only be applicable to iron powders with very high carbon level in feed powders and not for powders where the initial carbon is relatively low to lower considerable amount of oxygen.
GB1425195A and RU2179498C1 also discusses a similar method where annealing is done above 1000oC as the former except that the atmosphere of annealing is hydrogen rich gas such as cracked ammonia and pure hydrogen respectively where hydrogen acts as the main reducing agent to lower the oxygen levels. In addition to the decarburization step, hydrogen is again the main reducing agent to bring down the high oxygen levels of the feed iron powders in the complex annealing process for Patents CA1331096C and CA2261235A1 also. Therefore, to lower the oxygen levels of the iron powders hydrogen is primarily the main deoxidizing or reducing agent at temperatures above 1000oC. The reduction annealing for sponge or reduced iron powders are also commercially carried out by employing hydrogen gas. Also, hydrogen is an expensive gas and requires a lot of safety precautions for handling, usage and storage further adding to infrastructure costs.
The present disclosure is directed to overcome one or more limitations stated above or any other limitation associated with the prior arts.

SUMMARY OF THE DISCLOSURE
One or more shortcomings of the prior art are overcome by method and a product as claimed and additional advantages are provided through the method as described in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the present disclosure, a method for deoxidizing iron powder through reduction-annealing process is disclosed. The method of deoxidation comprises, mixing of iron powder with graphite powder to obtain iron-graphite powder mixture. The iron-graphite powder mixture thus obtained is then blended to obtain a homogenized iron-graphite powder mixture. This homogenized iron-graphite powder mixture is subjected to annealing at a temperature range of 1000°C to 1200°C for about 1 hr to 2 hrs. The annealing process reduces the homogenized iron-graphite powder mixture to an iron cake and deoxidizes the iron which is subjected to cooling to room temperature.
In an embodiment, the deoxidized iron cake thus produced is then crushed to granules of size 2 mm or less further subjected to milling to iron powder of size 150 micron or less.
In an embodiment, the iron powder having a density of 2.55 g/cc or less.
In an embodiment, the iron powder has an average particle size ranging from 15 µm to 100 µm.
In an embodiment, the iron powder has composition of Iron – at least 98 wt%; Carbon - 0.03 wt% to 0.08 wt% and Oxygen - 0.4 wt% to 0.5 wt%.
In an embodiment, the graphite powder having a fixed carbon of at least 98 wt%.
In an embodiment, the graphite powder in range of 0.3wt% to 0.4wt% is added to the iron powder.
In an embodiment, the annealing is carried out in a fixed bed-type furnace.
In an embodiment, the annealing of homogenized iron-graphite powder is carried out in an inert atmosphere preferably in a nitrogen atmosphere.
In an embodiment, the cooling of the annealed iron cake is carried out in an inert atmosphere preferably in a nitrogen atmosphere.
In an embodiment, the milling is carried out in hammer mill.
In an embodiment, the oxygen concentration in the iron power after reduction-annealing processing is less than 0.3 wt%.
In another non-limiting embodiment of the disclosure, the iron powder has final composition of Iron – above 98.5 wt% Carbon - 0.02 wt% to 0.09 wt% and Oxygen - 0.3 wt% or less.
It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The novel features and characteristics of the disclosure are set forth in the appended description. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

Figure.1 is a flowchart illustrating a method for deoxidizing iron powder through reduction-annealing process, according to an exemplary embodiment of the present disclosure.

Figure.2 illustrates a microscopic image of irregular iron powder A, according to an exemplary embodiment of the present disclosure.

Figure.3 illustrates a microscopic image of irregular iron powder B, according to an exemplary embodiment of the present disclosure.

Figure.4 illustrates a microscopic image of irregular iron powder C, according to an exemplary embodiment of the present disclosure.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the description of the disclosure. It should also be realized by those skilled in the art that such equivalent methods do not depart from the scope of the disclosure. The novel features which are believed to be characteristic of the disclosure, as to method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular form disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a method that comprises a list of acts does not include only those acts but may include other acts not expressly listed or inherent to such method. In other words, one or more acts in a method proceeded by “comprises… a” does not, without more constraints, preclude the existence of other acts or additional acts in the method.

Embodiments of the present disclosure discloses a method for deoxidizing iron powder through reduction-annealing process. Iron powders are widely used in the applications such as biomedical, magnetic, oxygen absorption, automotive and powder metallurgical applications. These iron powders can be produced commercially by the techniques such as mechanical, chemical, electrolytic, atomization etc. Mechanical methods may include machining, milling, chopping etc. Chemical methods may include reduction, precipitation, thermite reduction etc. Atomization methods may include gas and water atomization. The iron powders as produced by some of the above-mentioned methods which have varying level of purity depending upon the method used for its production. However, carbon and oxygen are major constituents in all the iron powders and are undesirable if they are in high percentages. The presence of carbon and oxygen is highly undesirable when such powders are put to powder metallurgical applications. The carbon and oxygen impair the compressibility and sinterability of these iron powders. If such powders are used for manufacturing sintered components/parts, then they will show poor mechanical strength which is undesirable. This may be attributed to the formation of oxide inclusions. Conventionally, these iron powders can be ad-mixed with graphite powders in addition to certain alloying elements such as copper, nickel etc., where the alloying elements may be in pre-alloyed form or diffusion bonded to iron powders. This improves the compressibility. But the oxygen content in these iron powders will affect the final sintering behaviour in these systems and hence, higher graphite additions will be required to compensate for the higher oxygen. Reduction annealing is another conventional method for deoxidation of iron powders carried out by employing hydrogen gas. But hydrogen is an expensive gas and requires a lot of safety precautions for handling, usage and storage further adding to infrastructure costs. Therefore, there is a need to develop a cost-effective method to produce low carbon-low oxygen iron powder which are ideal. for powder metallurgical applications.
According to various embodiments of the disclosure, a method for deoxidizing iron powder through reduction-annealing process is disclosed. The method includes the mixing of unalloyed reduced iron powder with high purity graphite powder. The iron powder comprises Iron (Fe) of at-least 98.5 wt%, Carbon (C) below 0.08wt% and Oxygen (O) in the range from 0.45wt% to 0.55 wt% with an apparent density of at-most 2.5 g/cc. The high purity graphite powder is having a fixed carbon of at-least 98.5 wt%. These elements are subjected to mixing which produces iron-graphite powder mixture. Further, the iron-graphite powder mixture is subjected to blending to obtain a homogenized iron-graphite powder mixture. The homogenized iron-graphite powder mixture thus produced is subjected to annealing in a fixed bed-type reduction furnace. Annealing involves heating the homogenized iron-graphite powder mixture at temperatures ranging from 1000 oC to 1200oC for about 1 to 2 hours. In an embodiment, the graphite powder in range of 0.3wt% to 0.4wt% is added to the iron powder. In an embodiment, the blending of iron-graphite powder mixture to form the homogenized iron-graphite powder mixture is carried out in a blender, wherein the blender is at least one of a double cone blender, V-type blender, W-type blender, Y-type blender, or any other commercial blender that serves the purpose.
Followed by, heating which is carried out under an inert gas atmosphere such as nitrogen. Based on this, a deoxidized iron powder cake is obtained after the annealing step. This is further followed by cooling the deoxidized iron powder cake to room temperature under an inert gas atmosphere such as nitrogen. The cooled deoxidized iron powder cake is further subjected to crushing to reduce the deoxidised iron powders to granules of size 2 mm or less. Finally, these deoxidised iron powders granules are subjected to milling, to reduce the deoxidised iron powder granules to a size of 150 micron or less.
Now referring to Figure 1, which illustrates a flowchart for a method for deoxidizing iron powder through reduction-annealing process. The present disclosure proposes a cost-effective method for deoxidation of iron powders produced by reduction technique. The method is now described with reference to the flowchart blocks described in figure 1. The order in which the method is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from the scope of the subject. The method is particularly applicable for iron powders produced by reduction process and it may also be extended to other type of ores.

The method for deoxidizing iron powder according to the present disclosure consists of mixing and blending predetermined quantity of iron powder and graphite powder.

Referring to block 102, the iron powder and the graphite powder is mixed to obtain a homogenized iron powder-graphite mixture. In an embodiment, mixing of the iron powder and the graphite powder may be carried out in commercially available blenders like double cone-type, V-type, W-type or Y type blenders to obtain the homogenized iron powder-graphite mixture which is indicated in block 103. Further, the homogenized iron powder-graphite mixture is subjected to annealing at a temperature ranging from 1000°C to 1200oC for a time period of 1 to 2 hrs as indicated in block 104. In an embodiment, the annealing may be carried out in a fixed bed-type reduction furnace under an inert atmosphere such as nitrogen. However, the same shall not be considered as limitation, since any other inert gas or reduction furnace may be used that serves the purpose of annealing. Further, due to the annealing, a deoxidised iron cake is obtained after the which is then subjected to cooling. The cooling of the deoxidised iron cake is carried out until the temperature reaches a room temperature. This is simply done by switching off the reduction furnace as indicated in block 105. At these temperatures, the graphite present as free carbon can reduce in all forms of iron oxides effectively to form CO(g):
?Fe?_2 O_3/?Fe?_3 O_4/FeO(s) + C(s) =Fe(s) +CO(g)
Further, the cooled deoxidised iron cake is then crushed in a jaw crusher to granules ranging in size of 2 mm or less as indicated in block 106. The crushed granules of the deoxidised iron cake are further milled in a hammer mill to deoxidised iron powder of size 150 micron or less as indicated in block 107. In an embodiment, the crushing and grinding of the granules of the deoxidised iron cake may be carried out in any other crusher or milling units that serves the purpose and is not limited to only the jaw crusher or hammer mill. After completion of the crushing and grinding process and when the deoxidised iron cake is at an acceptable size, the iron powder so obtained comprises low carbon and low oxygen which is indicated in block 108. In an embodiment, the iron powders thus produced is suitable for powder metallurgical applications as stated above.

Experiment and Test study:

Table 1 illustrates three different kinds of iron powders i.e. A, B and C that can be used in different embodiments of the present disclosure. These are manufactured from different raw materials through hydrogen reduction technique. Iron powders A, B and C are having different morphology such as irregular-porous, irregular etc as stated in the table below.
TABLE 1
Powder Raw material Method of Reduction Morphology
A Iron oxide from acid regeneration process Hydrogen Reduction Irregular-Porous
B Mill Scale Hydrogen Reduction Irregular
C Commercially available - Irregular

Table 2 illustrates properties of the iron powders that is used in different embodiments of the present disclosure. The table illustrates different properties of iron powders i.e. A, B and C such as the total iron content, total carbon content, total oxygen content and the particle size.
TABLE 2
Properties of Iron Powders used in different embodiments
Powder Type of Iron Powder Fe (total)
[wt%] C
[wt%] Ototal
[wt%] Apparent Density [g/cc] D50
[µm]
A H-Reduced Iron Powder 98.60 0.016 0.450 1.1 19
B Mill Scale H-Reduced Iron Powder 98.27 0.02 0.491 2.0 65
C Commercially available 98.71 0.012 0.42 2.55 89

Table 3 illustrates properties of the graphite powder that is used in different embodiments of the present disclosure. The table illustrates different properties of graphite powder such as fixed carbon content, ash content, volatile matter content and the particle size.
TABLE 3
Properties of Graphite Powder used in the Embodiments
Parameters Values
Fixed Carbon [wt%] 98.27
Ash [wt%] 0.95
Volatile Matter [wt%] 0.78
D50 [µm] 6

TEST EXAMPLES AND RESULTS
TEST EXAMPLE 1
Referring to figure.2 which illustrates a microstructure of irregular iron powder A used in the present disclosure and in test experiments 1 to 6. In this test, 0.3 wt% of the graphite powder with properties as defined in Table 3, is added to iron powder A as mentioned in Table 2 and mixed homogenously in double cone blender for 15 mins. The mixture is then subjected to annealing at 1000oC for 60 mins under a continuous flow of nitrogen atmosphere in a reduction furnace such as pusher type. The annealed cake is then cooled to room temperature in separate cooling zone under the same nitrogen atmosphere and taken out. It is then crushed to size below 2 mm using jaw crusher and then fed to hammer mill. The Iron powder having particle size below 150 µm are collected and analysed for final C and O content using LECO C&S and LECO ONH analysers, respectively. Iron powders with C = 0.042wt% and O = 0.195 wt% were achieved in this process.

TEST EXAMPLE 2
In this test, the process to obtain iron powders is similar to test example 1, but differs in graphite addition, wherein annealing temperature is as per Table 4 [provided below] to obtain iron powders with C = 0.073wt% and O = 0.191wt%.
TEST EXAMPLE 3
In this test, the process to obtain the iron powder is similar to test example 1, but differs in graphite addition, wherein annealing temperature and time is as per Table 4 to obtain the iron powder with C = 0.081wt% and O = 0.188wt%.
TEST EXAMPLE 4
In this test, the process of to obtain the iron powder is similar to test example 1, but differs in graphite addition, wherein annealing temperature and time is as per Table 4 to obtain the iron powder with C = 0.061wt% and O = 0.182wt%.
TEST EXAMPLE 5
In this test, the process of to obtain iron powders is similar to test example 1 but differs in graphite addition, wherein annealing temperature and time is as per Table 4 to obtain the iron powder with C = 0.054wt% and O = 0.183wt%.
TEST EXAMPLE 6
In this test, the process of to obtain iron powders is similar to test example 1 but differs in annealing temperature as per Table 4 to obtain the iron powder with C = 0.02wt% and O = 0.174wt%.
TEST EXAMPLE 7
Referring to figure.3 which illustrates microstructure of irregular iron powder B used in test experiments 7 to 12. In this test, 0.3 wt% of graphite powder with properties as defined in Table 3 is added to iron powder B as mentioned in Table 2 and mixed homogenously in double cone blender for 15 mins. The mixture is then subjected to annealing at 1000oC for 60 mins under a continuous flow of nitrogen atmosphere in a reduction furnace such as pusher type. The annealed cake is then cooled to room temperature in separate cooling zone under the same nitrogen atmosphere and taken out. It is then crushed to size below 2 mm using jaw crusher and then fed to hammer mill. Iron powders having particle size below 150 µm are collected and analysed for final C and O content using LECO-C&S and LECO-ONH analysers, respectively. Iron powders with C = 0.067wt% and O = 0.187wt% were achieved using this process.

TEST EXAMPLE 8
In this test, the process of to obtain iron powders is similar to test example 7 but differs in graphite addition and annealing temperature as per Table 4 to obtain iron powders with C = 0.061wt% and O = 0.175wt%.
TEST EXAMPLE 9
In this test, the process of to obtain iron powders is similar to test example 7 but differs in graphite addition, annealing temperature and time as per Table 4 to obtain iron powders with C = 0.04wt% and O = 0.121wt%.
TEST EXAMPLE 10
In this test, the process of to obtain iron powders is similar to test example 7 but differs in graphite addition, annealing temperature as per Table 4 to obtain iron powders with C = 0.025wt% and O = 0.135wt%.
TEST EXAMPLE 11
In this test, the process of to obtain iron powders is similar to test example 7 but differs in graphite addition and annealing time as per Table 4 to obtain iron powders with C = 0.034wt% and O = 0.184wt%.
TEST EXAMPLE 12
In this test, the process of to obtain iron powders is similar to test example 7 but differs in annealing temperature and time as per Table 4 to obtain iron powders with C = 0.059wt% and O = 0.153wt%.
TEST EXAMPLE 13
Referring to figure.4 which illustrates microstructure of irregular iron powder C used in test experiments 13 to 15. In this test, 0.3 wt% of graphite powder with properties as defined in Table 3 is added to iron powder C as mentioned in Table 2 and mixed homogenously in double cone blender for 15 mins. The mixture is then subjected to annealing at 1000oC for 60 mins under a continuous flow of nitrogen atmosphere in a reduction furnace such as pusher type. The annealed cake is then cooled to room temperature in separate cooling zone under the same nitrogen atmosphere and taken out. It is then crushed to size below 2 mm using jaw crusher and then fed to hammer mill. Iron powders having particle size below 150 µm are collected and analysed for final C and O content using LECO-C&S and LECO-ONH analysers, respectively. Iron powders with C= 0.092wt% and O = 0.279wt% were achieved using this process.

TEST EXAMPLE 14
In this test, the process of to obtain iron powders is similar to test example 13 but differs in graphite addition, annealing temperature and time as per Table 4 to obtain iron powders with C = 0.041wt% and O = 0.19wt%.
TEST EXAMPLE 15
In this test, the process of to obtain iron powders is similar to test example 13 but differs in graphite addition, and annealing temperature as per Table 4 to obtain iron powders with C = 0.068wt% and O = 0.221wt%.
As indicated in the above test examples and paragraphs, Table 4 illustrates the processing parameters/conditions and the results attained from the examples 1 to 12 is pasted below. Further, the table illustrates type of powder i.e. A, B and C, wt% of graphite added, annealing temperature, time of annealing, and the final carbon and oxygen content in the examples 1 to 12.
TABLE 4
Processing Conditions and Results used in Examples 1-12
Example No. Iron Powder Graphite addition
[wt%] Annealing Temperature
[oC] Time

[mins] Cfinal

[wt%] Ofinal

[wt%]
1 A 0.30 1000 60 0.042 0.195
2 A 0.34 1050 60 0.073 0.191
3 A 0.40 1050 75 0.081 0.188
4 A 0.35 1000 120 0.061 0.182
5 A 0.32 1100 100 0.054 0.183
6 A 0.30 1200 60 0.02 0.174
7 B 0.30 1000 60 0.067 0.187
8 B 0.34 1100 60 0.061 0.175
9 B 0.40 1050 75 0.04 0.121
10 B 0.35 1200 60 0.025 0.135
11 B 0.32 1000 100 0.034 0.184
12 B 0.30 1050 120 0.059 0.153
13 C 0.3 1000 60 0.092 0.279
14 C 0.35 1050 120 0.041 0.19
15 C 0.4 1100 60 0.068 0.221

Some exemplary embodiments as mentioned in Table 4 illustrates that low carbon-low oxygen iron powders could be obtained by the method as disclosed in the present disclosure.
In an embodiment, annealing results in formation of the deoxidized iron cake since graphite will no longer be present in the final iron powder. This leads to ultra low carbon (C) levels in final iron powder which is desired.
In an embodiment, iron content in the iron powder which has undergone the above described method has an Iron composition of at least 98 wt% which inherently implies less Oxygen (O) content.
Equivalents:

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.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.