Claims:We Claim:

1. A method for extracting iron and phosphorus from a basic oxygen furnace (BOF) slag in the form of High Phosphorus Steel (HPS) alloy and a slag, the method comprising:
charging the basic oxygen furnace (BOF) slag along with a fluxing agent and carbon into an arc thermal plasma reactor;
introducing a predetermined volume of inert gas into the arc thermal plasma reactor;
generating an arc within the arc thermal plasma reactor by striking a plurality of graphite electrodes positioned in the arc thermal plasma reactor;
ionizing the inert gas by the arc to form plasma, wherein the plasma is at a temperature range of 1600ºC to 1800ºC;
wherein the presence of plasma and carbon, reduces an iron oxide and a phosphorous oxide present in the basic oxygen furnace (BOF) slag at the plasma temperature such that, the iron oxide is reduced to iron and the phosphorous oxide is reduced to phosphorus thereby obtaining High Phosphorus Steel (HPS) alloy and the slag consisting of tri-calcium silicate (C3S).

2. The method as claimed in claim 1, wherein the basic oxygen furnace (BOF) slag has an initial composition of:
Iron Oxide (FeO) – 18 to 25%;
Calcium Oxide (CaO) - 30 to 36%;
Silicon Oxide (SiO2) - 8 to 10%;
Magnesium Oxide (MgO) - 4 to 6%;
Manganese Oxide (MnO) - 0 to 1%;
Phosphorous Oxide (P2O5) – 2 to 4%.

3. The method as claimed in claim 1, wherein the fluxing agent is a Silica based flux having composition traces of Sodium oxide (Na2O) and Alumina.

4. The method as claimed in claim 1, wherein the inert gas is Argon (Ar).
5. The method as claimed in claim 1, wherein the separated basic oxygen furnace (BOF) slag comprising tri-calcium silicate (C3S) forms a floating layer of slag over the iron and phosphorous.

6. The method as claimed in claim 1, wherein the reduction reaction for iron oxide (FeO) is,
FeO + C = Fe + CO.

7. The method as claimed in claim 1, wherein the reduction reaction for the phosphorous oxide (P2O5) is,
P2O5 + 5C = 2P + 5CO.

8. An arc thermal plasma reactor (100) for ionization and reduction of iron and phosphorus from a basic oxygen furnace (BOF) slag, comprising:
a crucible (1), wherein the crucible (1) is configured to receive a charge containing the basic oxygen furnace (BOF) slag and a fluxing agent;
a cover lid (2) provided over the crucible (1), wherein the cover lid (2) accommodates a first electrode (3a) of a plurality of graphite electrodes (3);
a passage hole (4) defined in the first electrode (3a) of the plurality of graphite electrodes (3), wherein the passage hole (4) receives a predetermined volume of an inert gas (6) channeled into the crucible (1);
a second electrode (3b) of the plurality of electrodes (3) connectable to the crucible (1), wherein at least one of the first electrode (3a) and second electrode (3b) of the plurality of graphite electrodes (3) is displaced to strike the other electrode of the at least one of the first electrode (3a) and second electrode (3b)to generate an arc (5) and form plasma, such that,
ionizing the inert gas (6) by the plasma, wherein the plasma is at a temperature range of 1600ºC to 1800ºC, resulting inreduction of an iron oxide and a phosphorous oxide present in the basic oxygen furnace (BOF) slag at the plasma temperature in presence of carbon, wherein the iron oxide is reduced to iron and the phosphorous oxide is reduced to phosphorus thereby making a high Phosphorus Steel alloy and the slag consisting of tri-calcium silicate (C3S).

9. The arc thermal plasma reactor (100) as claimed in claim 8, wherein the crucible (1) is a graphite crucible.

10. The arc thermal plasma reactor (100) as claimed in claim 8, wherein the first electrode (3a) is designated to be a graphite cathode electrode.

11. The arc thermal plasma reactor (100) as claimed in claim 8, wherein the second electrode (3b) is designated to be a graphite anode electrode.

12. The arc thermal plasma reactor (100) as claimed in claim 8, wherein the inert gas (6) is Argon (Ar).

13. The arc thermal plasma reactor (100) as claimed in claim 8, wherein the first electrode (3a) is displaced by a mechanism such as a rack and pinion mechanism.

14. A basic oxygen furnace (BOF) slag processed by the method as claimed in claim 1, comprises a composition of
Iron Oxide (FeO) – 7 to 9%;
Calcium Oxide (CaO) – 40 to 48%;
Silicon Oxide (SiO2) – 14 to 30%;
Magnesium Oxide (MgO) - 4 to 6%;
Manganese Oxide (MnO) - 0 to 1%;
Phosphorous Oxide (P2O5) –0.5 to 2 %.
Dated this 31st day of March 2021

GOPINATH A.S
OF K&S PARTNERS
IN/PA 1852
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 EXTRACTING IRON AND PHOSPHORUS FROM A BASIC OXYGEN FURNACE SLAG”

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

Nationality: INDIAN

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 metallurgy. Particularly, but not exclusively, the present disclosure relates to a method of processing a slag obtained from a metallurgical furnace for producing high phosphorous steel. Further, embodiments of the disclosure disclose the method extracting iron and phosphorus present in from basic oxygen furnace (BOF) slag and converting the same to usable slag.

BACKGROUND OF THE DISCLOSURE

A metallurgical furnace is employed in metal manufacturing industries to produce a required metal. Generally, the metallurgical furnace is defined as a vessel, to which raw materials are fed and other elements are introduced for producing a molten metal. The other elements may be injected into the metallurgical furnace in various forms such as, solid, liquid, and gaseous form, depending on nature of supplement and considering phase of molten metal being produced in the metallurgical furnace. One such supplement injected into the metallurgical furnace in the gaseous form may be including, but not limited to, oxygen and inert gases, which may be configured to oxidize the molten metal and provide inert surroundings for induced chemical reaction and agitation of the molten metal, to process the molten metal into a required metal or alloy.

Steelmaking process involves removing impurities from hot metal by treating it with oxygen. Such treatment and the impurities obtained from this treatment forms oxides which are known as slag. Slag is essential in high temperature metallurgical processing to purify molten metal with minimal cost. Large volume of slag is produced annually during different metallurgical processes, leading to important economic and ecological issues regarding their afterlife. To maximise the recycling potential, slag processing has become an integral part of valorisation chain. The slag that is generated after steelmaking via Basic Oxygen Furnace (BOF) converter process contains ~20% of iron (Fe) in oxide form along with phosphorous which make it unsuitable for any further application except landfills. This slag also contains different phases like di-calcium silicate (2CaO-SiO2 or C2S) which are also not suitable to be reused in any other processes like cement manufacturing. Ideally, slag containing tri-calcium silicate is a better by product, which can be used for cement manufacturing. Moreover, such slag should contain less amount of Iron (Fe) oxide and phosphorus pentoxide (P2O5). Presence of high amount of P2O5 hinders the recyclability of BOF slag in other steelmaking processes to utilize the calcium oxide (CaO) present in the BOF slag as this can lead to reversal of phosphorous into steel melt. Therefore, it becomes crucial for the separation of the iron (Fe) bearing components along with phosphorus (P) so that the slag can be used in different processes.

BOF slag (i.e., Fe (total)18-25%, CaO-30-36%, SiO2-8-10%, MgO-4-6%, MnO-0-1% and P2O5-2-4%) could not be recycled or reused and utilized in industries such as cement industries due to presence of di-calcium silicate (2CaO-SiO2 or C2S). Also, the presence of high amount of P2O5 hinders the recyclability of BOF slag in other steelmaking processes.

The present disclosure is directed to overcome one or more limitations stated above or any other limitation associated with the conventional arts.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of the prior art are overcome by a 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 disclosure, a method for extracting iron and phosphorus from a basic oxygen furnace slag in the form of High Phosphorus Steel alloy and a slag is disclosed. The method includes aspects of charging the basic oxygen furnace slag along with a fluxing agent and carbon into an indigenously developed extended arc thermal plasma reactor. The method further includes introducing a predetermined volume of inert gas into the arc thermal plasma reactor. Subsequently, an arc within the arc thermal plasma reactor is generated by striking a plurality of graphite electrodes positioned in the arc thermal plasma reactor. Generation of the arc results in ionization of the inert gas to form plasma, where the plasma is at a temperature range of 1600ºC to 1800ºC. The presence of plasma, carbon, reduces an iron oxide and a phosphorous oxide present in the basic oxygen furnace slag at the plasma temperature such that the iron oxide is reduced to iron and the phosphorous oxide is reduced to phosphorus thereby making the High Phosphorus Steel (HPS) alloy and the slag consisting of tri-calcium silicate.

In an embodiment, the basic oxygen furnace slag has an initial composition of Iron Oxide (FeO) – 18 to 25%; Calcium Oxide (CaO) - 30 to 36%; Silicon Oxide (SiO2) - 8 to 10%; Magnesium Oxide (MgO) - 4 to 6%; Manganese Oxide (MnO) - 0 to 1%; and Phosphorous Oxide (P2O5) – 2 to 4%.

In an embodiment, the fluxing agent is a Silica based flux having composition traces of Sodium oxide (Na2O) and Alumina and the inert gas is Argon (Ar).
In an embodiment, the separated basic oxygen furnace slag comprising tri-calcium silicate forms a floating layer of slag over the iron and phosphorous.

In an embodiment, the reduction reaction for iron oxide (FeO) is, FeO + C = Fe + CO and the reduction reaction for the phosphorous oxide (P2O5) is, P2O5 + 5C = 2P + 5CO.

In another non limiting embodiment of the disclosure, an arc thermal plasma reactor for ionization and reduction of iron and phosphorus from a basic oxygen furnace slag is disclosed. The reactor includes a crucible, and the crucible is configured to receive a charge of the basic oxygen furnace slag and a fluxing agent. A cover lid is provided over the crucible, where the cover lid accommodates a first electrode of a plurality of graphite electrodes. A passage hole is defined in the first electrode of the plurality of graphite electrodes, where the passage hole receives a predetermined volume of an inert gas channelled into the crucible. Further, a second electrode of the plurality of electrodes is connectable to the crucible, where at least one of the first electrode and the second electrode of the plurality of graphite electrodes is displaced to strike the other electrode to generate an arc and form plasma. Thus, the inert gas is ionized by the plasma, where the plasma is at a temperature range of 1600ºC to 1800ºC. Further, reduction of an iron oxide and a phosphorous oxide present in the basic oxygen furnace slag occurs at the plasma temperature in presence of carbon, where the iron oxide is reduced to iron and the phosphorous oxide is reduced to phosphorus thereby making a high Phosphorus Steel alloy and the slag consisting of tri-calcium silicate.

In an embodiment, the crucible is a graphite crucible. The first electrode is designated to be a graphite cathode electrode and the second electrode is designated to be a graphite anode electrode.

In an embodiment, the inert gas is Argon, and the first electrode is displaced by a mechanism such as a rack and pinion mechanism.

In an embodiment, a basic oxygen furnace slag processed by the method as disclosed above, includes a composition of Iron Oxide (FeO) – 7 to 9%; Calcium Oxide (CaO) – 40 to 48%; Silicon Oxide (SiO2) – 14 to 30%; Magnesium Oxide (MgO) - 4 to 6%; Manganese Oxide (MnO) - 0 to 1%; and Phosphorous Oxide (P2O5) –0.5 to 2 %.

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:

Fig. 1 is a flowchart illustrating a method for extracting iron and phosphorus from a basic oxygen furnace (BOF) slag, according to an exemplary embodiment of the present disclosure.

Fig. 2 is a schematic view showing an arc thermal plasma reactor, according to an exemplary embodiment of the present disclosure.

Fig. 3 is a graphical representation showing XRD Analysis of output slag after plasma processing, according to an exemplary embodiment of the present disclosure.

Fig. 4 shows micrographic view of heating of input and output slag, according to an exemplary embodiment of the present disclosure.

Fig. 5 shows micrographic view of phosphorus in the produced alloy, 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 embodiments thereof have 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 extracting iron and phosphorus from a basic oxygen furnace slag in the form of High Phosphorus Steel alloy and usable slag. Steelmaking process involves removing impurities from hot metal by treating it with oxygen and the impurities form oxides which are known as slag. To maximise the recycling potential, slag processing has become an integral part of the valorisation chain. Slag generated after steelmaking via Basic Oxygen Furnace (BOF) converter process contains ~20% of iron (Fe) in oxide form along with phosphorous which make it unsuitable for any further applications. The slag also contains different phases like di-calcium silicate (2CaO-SiO2 or C2S) which is also not suitable to reuse the slag in any other processes like cement manufacturing. Slag containing tri-calcium silicate is a better product, which can be added for making cement. Also, the slag should contain less amount of Fe oxide and phosphorus pentoxide (P2O5). Presence of high amount of P2O5 hinders the recyclability of BOF slag in other steelmaking processes to utilize the calcium oxide (CaO) present in the BOF slag as this can lead to reversal of phosphorous into steel melt.

According to various embodiments of the disclosure, a method for extracting iron and phosphorus from a basic oxygen furnace slag in the form of High Phosphorus Steel alloy and a slag. The method includes aspects of charging the basic oxygen furnace slag along with a fluxing agent and carbon into an arc thermal plasma reactor. Further, a predetermined volume of inert gas is introduced into the arc thermal plasma reactor. Subsequently, an arc within the arc thermal plasma reactor is generated by striking a plurality of graphite electrodes positioned in the arc thermal plasma reactor. Thus, the inert gas is ionized by the arc to form plasma, where the plasma is at a temperature range of 1600ºC to 1800ºC. The presence of plasma, carbon, reduces an iron oxide and a phosphorous oxide present in the basic oxygen furnace slag at the plasma temperature such that the iron oxide is reduced to iron and the phosphorous oxide is reduced to phosphorus thereby making the HPS alloy and the slag consisting tri-calcium silicate.

Henceforth, the present disclosure is explained with the help of figures for a method of extracting iron and phosphorus from a basic oxygen furnace (BOF) slag. However, such exemplary embodiments should not be construed as limitations of the present disclosure since the method may be used on other types of where such need arises. A person skilled in the art may envisage various such embodiments without deviating from scope of the present disclosure.

A basic oxygen furnace (BOF) may be used as a part of steel manufacturing process equipment. BOF is essentially used for removing impurities from the molten metal. Such process involves involves removing impurities from hot metal by treating it with oxygen and the impurities from oxides which are known as basic oxygen furnace (BOF) slag (herein after referred to as the BOF slag). The detailed composition of BOF slag is presented in the below Table 1.
Components (%) Iron (Fe) Calcium oxide (CaO) Silicon dioxide (SiO2) Magnesium oxide (MgO) Manganese oxide (MnO) Phosphorus pentoxide (P2O5)
BOF Slag 18-25 30-36 8-10 4-6 0-1 2-4

It can be observed that, the slag from BOF contains large compositions of iron bearing compounds along with Phosphorus pentoxide (P2O5) which hinders the use of this slag directly for various applications including manufacturing of cement. The iron and phosphorus containing compounds may be reduced and may be separated from the slag by an arc thermal plasma reactor (200). The slag may be used for making cement or can be reused in the steel industry. The method of separating the iron and phosphorus containing compounds and the slag containing tri-calcium silicate (C3S) is explained with greater detail below.

Fig. 1 is a flowchart illustrating a method for extracting iron and phosphorus from a basic oxygen furnace (BOF) slag in the form of High Phosphorus Steel (HPS) alloy and a slag containing tri-calcium silicate (C3S). Based on the method disclosed in fig .1, the first step involves charging the basic oxygen furnace (BOF) slag along with a fluxing agent and carbon into the arc thermal plasma reactor (100) [shown in fig. 2]. In an embodiment, the fluxing agent may be a Silica based fluxing agent having composition traces of Sodium oxide (Na2O) and Alumina. In an embodiment, the carbon added herein may act as a reductant and may enhance the recovery of iron (Fe) from BOF slag in the arc thermal plasma reactor (100). The BOF slag along with the fluxing agent and the carbon may be loaded into a crucible (1) of the arc thermal plasma reactor (100). The arc thermal plasma reactor (100) may include a plurality of electrodes (3). The plurality of electrodes may include a first electrode (3a) and a second electrode (3b). At least one of the first electrode (3a) may be a cathode electrode and the second electrode (3b) may be an anode.

Further, in step 102, a predetermined volume of inert gas is introduced into the arc thermal plasma reactor (100). In an embodiment, the inert gas introduced in the arc thermal plasma reactor (100) may be Argon (Ar). The inert gas may be introduced into the crucible (1) through a passage hole defined in the first electrode (3a). Step [103] relates to the aspect of generating an arc (5) within the arc thermal plasma reactor (100) by striking the plurality of graphite electrodes (3a and 3b) positioned in the arc thermal plasma reactor (100). A reciprocating motion may be imparted to the first electrode (3a) such that the first electrode (3a) may be brought proximal to the second electrode (3b) for striking the arc (5). In an embodiment, the reciprocating motion may be imparted by a rack and pinion arrangement. The first electrode (3a) may be connected to the rack and pinion arrangement [not shown in figures] such that, actuation of the rack and pinion arrangement traverses the first electrode in a to and fro motion.

In an embodiment, as soon as the power to the reactor is switched ON, the first electrode (3a) may slowly be pulled upwards after striking the arc (5) within the crucible (1). The arc current and voltage may be regulated during the course arching. The arc (5) generated by the electrodes (3a and 3b) ionizes the inert gas to form plasma and the plasma may be at a temperature range of 1600ºC to 1800ºC.

In an embodiment, the presence of plasma, carbon and the fluxing agent reduces the iron oxide and the phosphorous oxide present in the BOF slag at the plasma temperature. The high temperature plasma causes the iron oxide to be reduced to iron and the phosphorous oxide to be reduced to phosphorus as illustrated in the below chemical equations numbered as 1 and 2.

FeO + C = Fe + CO……(1)
P2O5 + 5C = 2P + 5CO…(2)
Thus, the high phosphorus steel (HPS) alloy and the slag consisting of tri-calcium silicate (C3S) are separated from the BOF slag.

Referring to fig. 2, the arc thermal plasma reactor (100) used for separating the high phosphorus steel (HPS) alloy and the slag consisting of tri-calcium silicate (C3S) is explained below. The arc thermal plasma reactor (100) includes the crucible (1) made of graphite. The crucible (1) may be of a shape including but not limited to a rectangle. The crucible (1) may be configured to receive a charge of the BOF slag, fluxing agent, and carbon. Further, the crucible (1) may be supported by a crucible holder (7). The arc thermal plasma reactor (100) may include a cover lid (2) provided over the crucible (1) for enclosing the crucible (1). The cover lid (2) may also be of a material including but not limited to graphite. The cover lid (2) may be defined with at least one aperture for accommodating the first electrode (3) of the plurality of graphite electrodes (3a and 3b). The first electrode (3) may be a graphite cathode electrode and the first electrode (3) may be defined with the passage hole (4) extending axially through the first electrode (3). The passage hole (4) receives the predetermined volume of an inert gas (6) that is channelled into the crucible (1). Further, the first electrode (3a) may be oriented vertically inside the crucible (1). The position of the first electrode (3a) within the crucible (1) may be varied by any known mechanisms in the art including but not limited to a rack and pinion mechanism. The height of the first electrode (3a) from a bottom surface or from the second electrode (3a) may be varied suitably to strike and extend the arc (5) within the crucible (1). The arc thermal plasma reactor (100) may also include the second electrode (3b) which is connectable to the crucible (1). In an embodiment, the second electrode (3b) is a graphite anode electrode.

Test results and Examples:

Further, embodiments of the present disclosure will now be described with examples. Experiments have been carried out on the BOF slag by using method of the present disclosure.

Experiments are carried out in the temperature range of 1600 oC to 1800 oC. The plasma forming gas or the inert has and the graphite lid (2) enclosing the top of the crucible (1) which aids in maintaining desired atmosphere inside the hearth for preparation of charging the BOF slag.

Table 2 below provides details of the amount of components used to carry out the experiments.

BOF Slag (grams) Fluxing Agent (grams)
500 100 -200
Table 2: Components used for Experimentation

The parameters used for carrying out the experiment using the thermal plasma arc reactor (100) are mentioned in the below Table 3.

Current, A Voltage, V Time, mins Temperature, oC
200 -350 40-60 5-20 1600-1800
Table 3: Process Parameters used for Thermal plasma arc reactor.
Further, after the slag is charged in to the crucible, the fluxing agent and the carbon are loaded into the crucible (1), the arc (5) is struck by the plurality of electrodes (3a and 3b) with the operational parameters of the arc as mentioned above in the Table 3. After subjecting the BOF slag to high temperatures, plasma is generated as disclosed in the above-mentioned method. The iron oxide is reduced to iron and the phosphorous oxide is reduced to phosphorus in the BOF slag. Consequently, the metallic component and the slag components are separated. Further, high phosphorus steel (HPS) alloy and the slag consisting of tri-calcium silicate (C3S) is obtained from above-mentioned process. The output slag obtained after the above-mentioned plasma treatment process is evaluated for chemical composition, phases, and important properties. The chemical composition of the output slag remained after plasma treatment is presented in the below Table 4.

Components (%) Fe(Total) CaO SiO2 MgO MnO P2O5
Output Slag 7-9 40-48 14-30 4-6 0-1 0.5-2
Table 4: Output slag composition after plasma treatment

It can be observed that, 70% of iron containing compound has been reduced and is formed in a separable metallic phase. Also, most of the P2O5 has been reduced drastically thereby, making the remaining slag usable.

Fig. 3 is a graphical representation showing XRD Analysis of output slag after plasma processing and Fig. 4 shows micrographic view of heating of input and output slag. It is evident from the Fig. 3 that the output slag contains maximum amount of tri-calcium silicate (C3S) which is suitable for addition in cement making process. Also, by studying the softening and melting behaviour using a heating microscope (Figure 3) suggests a good 70-80 oC reduction during melting. Thus, the overall process and the steelmaking process is enhanced. Also, it was observed that composition of P2O5 was also lowered drastically.

The composition of the metallic content produced after plasma treatment is shown in the below Table 5.
Components (%) C Al P Si Mn S
Metallic Component 0.8-1.2 0.01 0.9-2.0 0.1 0.1-0.2 0.01
Table 5: Composition of high P containing steel produced from BOF slag
It can be seen that the metallic component contains ample amount of phosphorus reduced from slag phosphorus pentoxide. A further addition of phosphorus by adding phospherite mineral during the plasma treatment will ensure the production of ferro-phos.

Fig. 5 shows micrographic view of phosphorus in the produced alloy. As observed from Fig. 5, the phosphorus distribution is uniform in the metallic component. The light-coloured particles in the Fig. 5 are indicative of phosphorus in the metallic component. Also, the phase analysis of phosphorus containing steel using XRD verifies the phases formed after the treatment of slag in the arc thermal plasma reactor (100).

In an embodiment, the above-mentioned method of processing the BOF slag enables the extraction of iron and phosphorus present in the BOF slag to produce usable slag as well as high phosphorous steel. Further, the above-mentioned arc thermal plasma reactor (100) that produces high temperature arc may reduce the reaction time and the processing time of the BOF slag considerably.

In an embodiment, the iron oxide and phosphorus in the BOF slag is reduced to iron and phosphorus respective, thereby making the High Phosphorus Steel (HPS) alloy and the slag consisting of tri-calcium silicate (C3S).

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.

Referral Numerals

Referral Numerals Description
1 Crucible
2 Lid of the crucible
3 Electrodes
3a First electrode
3b Second electrode
4 Passage hole
5 Arc
6 Inert gas
7 Crucible holder
200 Arc thermal plasma reactor