TECHNICAL FIELD
The present disclosure relates to metallurgy. Particularly, but not exclusively, the present disclosure relates to manufacturing of stainless steel scrap. Further, embodiments of the present disclosure disclose a method for manufacturing 200 series stainless steel scrap from chromite tailings and sub-grade manganese ore.
BACKGROUND OF THE DISCLOSURE
Chromium is one of the elements which is widely employed in a steel manufacturing plant, where inclusion of chromium imparts different properties to the steel. Chromium is also widely used in the steel manufacturing plants as refractory, refractory lining, chemical agent, and the like, for selectively regulating thermal conditions of the plant and/or chemical reaction occurring therein. Further, chromite ore may be one of the sources of producing chromium for use in the steel manufacturing plants. Like most of the heavy metals, chromite ores are generally treated by gravity separation process for refinement, which in turn produces filtered material that may in form of fine-sized tailings (<25 µm) having higher silica content. Such tailings may cause environmental hazards and have considerable amount of metallic content which may get untapped in most of the ferrochrome production plants. Generally, such tailings generated are dumped in dump yards of the steel manufacturing plants, which may raise concern of space as well as environment pollution.
Furthermore, manganese is also one of the important alloying elements for steel manufacturing, as manganese tends to affect brittleness of manufactured steel, and also tends to improve strength of the steel.
There are few patents on utilizing the low-grade chromite ore tailings or chromite ore processing residue in a standalone basis for manufacturing of steel, and particularly, stainless steel. For example, Patent application US20040086438A1 [referred to as ‘438] discusses about simultaneous recovery of chromium and iron from chromite ore processing residue (COPR), which may be in the form of chromate salt and iron salt, which prevents exposure and/or entry of toxic metals into landfills in the manufacturing plant. The process disclosed by ‘438 involves treating COPR with a metal hydroxide, followed by leaching at temperature range of 30oC-100oC and other hydrometallurgical routes. However, process proposed by ‘438 is to recover chromium and iron as salt, which may have very restricted uses in manufacturing of the stainless steel.

Also, another example Patent CN101380510 [referred to as ’510] discusses about utilization of chromium slag via leaching route by converting hexavalent chromium to tri-valent chromium. The process of ‘510 further discusses to detoxify chromium slag and prepare nine other high-quality products namely, chromium, Magnesium and aluminum hydroxides, silicon dioxide, magnetic tri-iron tetroxide, calcium sulfate dihydrate, corundum intermediate, sodium chloride, tailings- chromite ore.
In other patent publications recovering chromium concentrate from tailings of high carbon ferrochrome dry and wet slag respectively, are discussed. While some Indian patent publications like IN20110068112, IN20140031612, IN201631008680A and IN201731008862 discuss about beneficiation of chromite tailings mostly for enrichment purpose.
Also, there are few patents publications that discuss about production of 200 series stainless steel, such as patent CN105671413 [referred to as ‘413], which uses electro-silicothermic process, where an ore is smelted to obtain the silicon-chromium alloy as low carbon intermediate alloy and manganese ore as refining agent. However, none of the above specified references discusses about eliminating intermediate steps in the production of stainless steel, to reduce CO2 emission and discards low-grade materials whereby creating environmental concerns.
The present disclosure is directed to overcome one or more limitations stated above.
SUMMARY OF THE DISCLOSURE
One or more shortcomings of the conventional process are overcome by a method as claimed and additional advantages are provided through the provision of such method as claimed 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 manufacturing 200 series stainless steel scrap is disclosed. The method includes steps of mixing, fine chromite tailings and a source of manganese with a powdered burden. The mixture is then pelletized into pellets of a predefined size. The pellets are smelted in a submerged arc furnace to produce molten

alloy and a slag over the molten alloy, where the molten alloy substantially includes 200 series stainless steel scrap.
In an embodiment, the source of manganese is at least one of sub-grade manganese ore and manganese carbide.
In an embodiment, the fine chromite tailing comprises Chromium to Iron in a ratio of 0.54 to 0.64 and chemical composition (in wt%) comprising Cr: 12-18%, Fe: 20-30%, SiO2: 20-26%, Al2O3:8-14%, Ni: 0.3-0.5 %.
In an embodiment, the sub-grade manganese ore contains Manganese to Iron ratio of 0.5 to 0.8 and chemical composition (in wt%) comprising MnO: 20-28 %, Fe: 30-40%, SiO2: 3-8%, Al2O3: 2-6%, MgO: 1-3%. The composition of the powdered burden includes lime, coke and powdered bentonite, with sub-grade manganese ore as source of manganese.
In an embodiment, Manganese carbide contains Mn7C3: 99% by wt.%. The composition of the powdered burden includes lime and powdered bentonite, with manganese carbide as source of manganese.
In an embodiment, coke and manganese carbide act as reductant for smelting process to produce the molten alloy and the slag.
In an embodiment, fines of the chromite tailing and source of manganese have particle size of less than 25 µm.
In an embodiment, the lime is powdered to include a particle size of less than 75um to blend with fines of the chromite tailing and sub-grade manganese ore.
In an embodiment, weight of the burden is determined based on an input basicity B and an input burden value are R (CaO+MgO/SiO2) = 0.8 to 1.2 and R (CaO+MgO/Al2O3) = 0.9-1.0, to maintain slag fluidity for separating the slag from the molten alloy.
In an embodiment, composition (in wt%) of the molten alloy consists at least of Fe: 65-82%, Cr: 12-20%, Si: 0.2-1.5%, C: 4.5-7%, Mn: 5-12% and Ni: 0.8-2%, with the sub-grade manganese ore as the source of manganese.
In an embodiment, composition (in wt%) of the molten alloy consists at least of Fe: 65-82%,

Cr: 12-20%, Si: 0.2-1.5%, C: 2-3.5%, Ni: 0.8-1.5 and Mn: 3-6, with manganese carbide as the source of manganese.
In an embodiment, composition (in wt%) of the slag includes CaO: 24-40%, MgO: 2-5%, SiO2: 30-38.4%, Al2O3: 12-19%, MnO: 5-13%, FeO: 2-5.2%, Cr2O3: 2-7%, with the sub-grade manganese ore as the source of manganese.
In an embodiment, composition (in wt%) of the slag includes CaO: 18-22%, MgO: 1-2%, SiO2: 15-22%, Al2O3: 10-13.5%, MnO: 28-35%, FeO: 3-6%, Cr2O3: 3-8%, with the manganese carbide as the source of manganese.
In an embodiment, the chromite tailings are mixed with powdered bentonite in concentration range of 1-2 wt.% and lime in concentration range of 16.5-22 wt.% for mixing and then pelletizing the mixture, with the sub-grade manganese ore as the source of manganese.
In an embodiment, the chromite tailings are mixed with powdered bentonite in concentration range of 1-3 wt.% and lime in concentration range of 18-25.72 wt.% for mixing and then pelletizing the mixture when the source of manganese is manganese carbide.
In an embodiment, the mixture includes a predefined quantity of water to mix the powdered burden with the fine chromite tailings and the source of manganese.
In an embodiment, the pellets produced by pelletizing of the mixture is dimensioned in a ranged of 8mm to 12mm.
In an embodiment, the submerged arc furnace is operated with a power input between 3500 to 4000kWhr/ton of the molten alloy, during smelting process.
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 together 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 characteristic of the disclosure are set forth in the appended claims. 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 flow chart illustrating a method for manufacturing 200 series stainless steel scrap, in accordance with an embodiment of the present disclosure.
Figure. 2 is a process flow diagram of manufacturing 200 series stainless steel scrap, in accordance with an 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 structures and 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 claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent processes do not depart from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristics of the disclosure, both as to its organization and 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. It will be readily understood that the aspects of the

present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.
Embodiments of the present disclosure discloses a method for manufacturing 200 series stainless steel. The method includes steps of mixing fine chromite tailings and a sub-grade manganese ore with a powdered burden. The mixture is then pelletized into pellets of a predefined size, where such pellets of the mixture are smelted in an arc furnace to produce molten alloy and a slag over the molten alloy. The molten alloy produced in the arc furnace substantially includes 200 series stainless steel and slag. Here, the fine chromite tailings and the sub-grade manganese ore are either residue or by-products or recovered landfill residue or waste of processing of chromite ore and manganese ore, respectively. With such utilization of low-grade material, the method is configured to produce 200 series stainless steel.
The phrase “200 series stainless steel” is to be considered as a class of stainless steel including austenitic microstructure and having corrosion-resistant properties. Further, 200 series stainless steel may be used in moist and/or chlorine or chloride environment, while such stainless steel also exhibits low to moderate tensile strength when compared stainless steel having ferrite microstructure. The phrase “200 series stainless steel scrap” is to be considered as precursor to make 200 series stainless steel.
The phrases “chromite tailings” and “source of manganese” (or otherwise termed as “low-grade manganese ore” from at least one of sub-grade manganese ore and manganese carbide) may be referred to as residual or debris material produced on refining and extracting high-quality of chromium and manganese from chromite ore and manganese source, respectively. Process for refining and extracting high-quality of chromium and manganese may be as per general practices, while the debris of such process may be required to be further processed such as, but not limited to, classification process (i.e., based on size), washing, chemical treatment, thermal treatment, and the like. Also, the debris containing low-quality (i.e., lower % by wt.) of chromium and manganese may be employable in the present disclosure without having to perform any chemical or thermal treatment. The low-quality of chromium which may be collected as debris from chromite treatment may be termed as “chromite tailings”, while manganese collected as debris from sub-grade manganese ore or manganese carbide may be subjected to thermal and/or chemical treatment to collectively referred to as “source of manganese” hereinafter in the description of the present disclosure. In one embodiment of the

present disclosure, the chromium tailings and the source of manganese may be procured, collected and/or extracted from at least one of landfill, chemical dump and residual dump of the manufacturing plant.
The terms “comprises”, “comprising”, or any other variations thereof used in the specification, are intended to cover a non-exclusive inclusion, such that the method that comprises steps does not include only those steps but may include other steps not expressly listed or inherent to such method. In other words, one or more steps proceeded by “comprises… a” does not, without more constraints, preclude the existence of other steps.
Henceforth, the present disclosure is explained with the help of one or more figures of exemplary embodiments. However, such exemplary embodiment should not be construed as limitation of the present disclosure.
The following paragraphs describe the present disclosure with reference to Figure.1 and 2, which are exemplary embodiment of the present disclosure illustrating a flow chart and process flow of a method for manufacturing 200 series stainless steel scrap [herein also interchangeably referred to as “steel” or “steel scrap”]. The steel may be manufactured by smelting in a furnace, where material may be quantitatively and/or periodically supplied into the furnace for manufacturing the steel in a molten alloy state. In the illustrative embodiment, the furnace is at least one of arc furnaces, which may be including, but not limited to, a submerged arc furnace, an electric arc furnace and any other arc furnace capable of reducing iron ore for the steel manufacturing. In an embodiment, the arc furnace may include a plurality of sensors, detectors, and/or indicators to suitably determine parameters of the smelting process and for producing the molten alloy in the form of the steel scrap. Such parameters may be including, but not limited to, temperature at various zones along the furnace, viscosity of the molten metal and slag, pressure within the furnace, rate of injection of material into the furnace, composition of the slag, and other parameters that may affect production of the steel.
In the illustrative embodiment, the steel is produced in the arc furnace by employing low-grade material. Such low-grade material may be procured and/or collected from at least one of landfill, chemical dump and residual dump of the manufacturing plant. The low-grade material employable in the method of the present disclosure may be including the chromite tailings and source of manganese which is at least one of the sub-grade manganese ore and manganese carbide. In an embodiment, the chromite tailings may be collected based on separation and

classification of residual waste or debris from processing of the chromite ore, where fine chromite tailings may be procured based on separation and classification ore for particle size diameter of less than 25 µm. The chromite tailings may include comparatively greater % by wt, of silica than % by wt. of chromium. The source of manganese may be procured from residue of processes manganese ore or employing manganese carbides as for mixing with the fine chromite tailings.
At block 101, the fine chromite tailings and the source manganese are mixed with a powdered burden. Composition of the burden may be selected based on source of manganese. In an embodiment, the burden may include lime, carbon and bentonite, when source of manganese is sub-grade manganese ore, while the burden may include lime and bentonite when source of manganese is manganese carbide. The burden is configured to act as charge in the arc furnace for producing the steel along with the slag. The burden may also employ a liquid binding agent including, but not limited to, water, to ensure proper mixing and maintaining consistency for introducing the burden along with the fine chromite tailings and the source of manganese, into the furnace. The lime of the burden may be powdered for mixing with the fine chromite tailings and the sub-grade manganese ore. In an embodiment, the lime is powdered to include a particle size of less than 75um to blend with fines of the chromite tailing and sub-grade manganese ore, while the bentonite may be added in powdered form to act as a binder to blend with fines of the chromite tailing and sub-grade manganese ore. In an embodiment, the chromite tailings are mixed with bentonite in the concentration range of 1-2 wt. %. And lime in the concentration range of 16.5-22 wt. %. In an embodiment, the chromite tailings are mixed with powdered bentonite in concentration range of 1-3 wt.% and lime in concentration range of 18-25.72 wt.% for mixing and then pelletizing the mixture when the source of manganese is manganese carbide. Further, at least one of the coke and manganese carbide act as a reductant for the smelting process to produce the molten alloy and the slag.
In an embodiment, carbon of the burden may be added either from the coal or processed coal or other carbonaceous material, when source of the manganese is sub-grade manganese ore while carbon may be derived when manganese carbide is used as source of the manganese ore. In the illustrative embodiment, carbon is added in the form of coke, where the coke contains fixed carbon in a range of 82-88% by wt. with volatile matter 0.5-1% by wt. and ash 10-14% by wt. Also, particle size of the coke may be at least 3 mm, meanwhile the coke that may be

having utmost dimension may be reduced and/or broken to be compared with that of 3mm dimension for suitably mixing with the chromite tailings and the sub-grade manganese ore.
The mixture of the chromite tailings, the source of manganese and the burden may then be agglomerated to be introduced into the arc furnace. As in block 102, the mixture is pelletized into defined dimensions for being introduced into the furnace. Such palletization of the mixture may be performed by compacting and/or densification. In an embodiment, compacting and/or densification of the mixture may be performed in a disc or a drum pelletizer or any other process that may be capable of producing pellets of mixture of the chromite tailings, the sub-grade manganese ore and the burden. In an embodiment, during palletization, the pellets formed from the mixture may include moisture of at least 5% by wt., and that such pellets may dried to reduce said moisture content therein. The pellets may be dried by positioning in a heating unit such as, but not limited to, an oven, where such oven may be at least one of a microwave oven, an electric oven, and the like. The drying of the pellets may also be performed through other heating units such as furnaces or baking units, capable of drying the pellets.
The pellets are disposed in a defined quantity into a vessel, where such vessel containing the pellets may be positioned in the furnace for heating, as in block 103. In an embodiment, each pellet may be dimensioned in a range of 7 to 15mm, where profile of such pellets may be including, but not limited to, cylindrical, cubical, cuboidal, spherical, hemi-spherical, and the like. Further, dimension of the pellets may not exceed dimension of the vessel, in order to be positioned in the furnace for producing the steel. In an embodiment, along with the pellets, the vessel also may be supplied with fluxing agents, to form the slag during smelting in the furnace. Further, the pellets in the furnace are subjected to heating through which compounds of the pellets are smelted to produce the molten alloy and the slag within the furnace. The fluxing agent may be including, but not limited to, lime, dolomite, hydrated lime, calcined lime and any other fluxing agent that may be capable of producing the slag separately from the molten alloy in the furnace, during smelting of the pellets in the vessel. The molten alloy formed in the furnace is 200 series stainless steel scrap.
In an embodiment, when the source of manganese is the sub-grade manganese ore, chemical composition of the steel may vary in the range of Fe: 65-82 wt%, Cr: 12-20 wt%, Si: 0.2-1.5 wt%, C: 2.5-7 wt% , Mn: 5-12 wt%, and Ni: 1-2 wt%. Also, the slag that may be generated with the steel, may be air cooled to include composition consisting of CaO: 24-40 wt%, MgO:

2-5 wt%, SiO2: 30-38.4 wt%, Al2O3: 12-19 wt%, MnO: 5-13 wt%, FeO: 2-5.2 wt%, Cr2O3: 2-7 wt%.
In an embodiment, when the source of manganese is manganese carbide, chemical composition of the steel may vary in the range of Fe: 65-82%, Cr: 12-20%, Si: 0.2-1.5%, C: 2-3.5%, and Mn: 3-6, while slag may include CaO: 18-22%, MgO: 1-2%, SiO2: 15-22%, Al2O3: 10-13.5%, MnO: 28-35%, FeO: 3-6%, Cr2O3: 3-8%.
In an embodiment, the vessel may be pre-heated for smelting the pellets within the furnace. On pre-heating of the vessel, the pellets may be introduced into the vessel and smelting process may be initiated, which may then be followed by holding or soaking of the smelting pellets till the molten alloy and slag are formed. In an embodiment, the vessel may already be pre-heated and containing a defined quantity of molten alloy and the slag, to which the pellets may be introduced for continuous smelting and production of the molten slag.
In an embodiment, composition of the chromite ore tailings contains chromite, alumina, quartz, silica, and iron oxide in greater quantity along with minimal or no goethite and others incidental compounds. Further, the lime in the burden may be employed in hydrated form to produce the slag and to maintain basicity ranging between 0.8-1.2. Also, the lime may consist of CaO in range of 55-68% by wt. with MgO by wt. of 1-8% and SiO2 1-8% by wt.
In an embodiment, neutrality of the burden may be determined to selectively vary composition of the burden for mixing with the chromite tailings and the sub-grade manganese ore. Determined neutrality may be considered for basicity as input basicity “B”, while burden weight may be analyzed as an input burden value “R” as a sum of wt% of lime, magnesium oxide and silica to be 0.8 to 1.2 or as a sum of wt.% of the lime, aluminium oxide and silica to be 0.9-1.0. Here, the B value is for basicity which controls viscosity of the slag, B value in the defined range may ensure that the slag is maintained in fluid state, and hence, aids in better slag-metal separation from the vessel during smelting. The input value R value indicates melting behavior of the slag, where lower value of R indicates higher Al2O3 in the slag, and hence, the slag may possess higher melting point than that of the molten alloy. Both the ratios of “B” and “R” may be required to be maintained with the defined values to optimize the slag temperature and the slag fluidity.

Table 1 below indicates composition of metals and/or compounds in the mixture with which the pellets are formed for producing 200 series stainless steel. By varying concentration of the compounds in the mixture, yield of the steel may be varied.

Constituents Cr-Tailings Sub-grade Mn Ore Coke Lime
Cr2O3 12-18
Fe(T) 20-30 30-40
SiO2 20-26 3-8 6-10 1-8
MgO 1-5% 1-3 <1 0-1.5
CaO 0-2 2-6 <1.5 55-68
Al2O3 8-14 2-6 <1
MnO 0-1 22-28
FC 80-87
Based on above values in Table 1, the pellets including varying weight of each of the compounds from the above table are subjected to smelting process in the furnace.
As a first example, the pellets are formed with 4.85 kg of chromite tailings, 1.94 kg sub-grade manganese ore, 2.11 kg of lime, 1.09 kg of Coke and 100 gm bentonite, which are blended for formation of such pellets. Additionally, water is added to maintain moisture 12% for pelletizing. Also, the mixture may be dried at 150oC for about 4 hours to form the pellets, which are introduced into the furnace for smelting. During smelting, the operation time consists of (a) heating the vessel for 30 min; (b) charging the pellets for 5-10 min; and (c) holding or soaking for 5-10 min. The heating of the vessel is performed by arcing between two electrodes that may be connected to the vessel. Charging of pellets in the crucible is initiated after the vessel may attain the defined temperature. The pellets are added slowly to the vessel in batches and is followed by charging operation in 5-10 minutes. During charging, temperature is maintained at 16000C with a buffer temperature of 500C, where temperature during the smelting process

was monitored by one or more infrared pyrometers. The holding time or soaking time may be 5-10 mins to the molten alloy. Also, the molten alloy and the slag are tapped from the furnace. The metallic and non-metallic parts is physically separable and recovered by breaking the cakes. The molten alloy is 200-series stainless steel having composition including, but not limited to, Si- 0.78 wt%, Fe-71.06 wt%, Cr- 14.20 wt%, Ni-1.12 wt%, C-5.7 wt%, Mn- 5.24 wt%, whereas the slag composition consists of: CaO-24.92 wt.%, MgO- 3.7 wt%, Al2O3-13.2 wt%, SiO2-32.77 wt%, MnO-3.72 wt%, Fe2O3- 3.42 wt%, Cr2O3- 4.06 wt.%.
As a second example, the pellets are formed with 150 gm of chromite tailings, 60 gm sub-grade manganese ore, 50.20 gm of lime, 40 gm coke and 3 gm of bentonite, which are blended for palletization. Water is added to maintain moisture 14 % for palletization, which is followed by drying the pellets in the oven at 150oC for 4 hrs. The pellets are introduced into a submerged arc furnace, where the pellets are smelted to produce the molten alloy and the slag. The submerged arc furnace is operated with a power input of about 4000kWhr/ton of the molten alloy, during smelting process. Composition of the molten alloy includes: Si-0.9 wt%, Fe-59.68 wt%, Cr-18.55 wt%, Ni-1.067 wt%, Mn-11.705 wt%, C-4.99 wt%, Si-3.942 wt.%. The Slag chemical composition consists of: CaO-39.45 wt%, MgO-4.27 wt%, Al2O3-18.74 wt%, SiO2-35.48 wt%, MnO-1.96 wt%, FeO-0.87 wt.%, Cr2O3- 2 wt.%.
As a third example, 333 gm of chromite tailings, 73.3 gm of lime, 100 gm of Mn3C and 6 gm bentonite are blended to make the charge mix. Sufficient water was added to make the moisture 12% followed by pelletizing. The formed pellets were oven dried at 150oC for 4 hrs. The pellets were taken for smelting. During smelting experiments the operation time consists of (a) heating the crucible for 30 min (b) charging the raw material for 5-10 min (c) holding or soaking for 5-10 min. The heating of the crucible was done by arcing between electrode and coke at bottom. Charging of raw materials into the crucible was started after it attains the desired temperature. The raw materials were added slowly to the crucible in small quantities and the charging operation completed in 5-10 minutes. During experiment the operation temperature was maintained at 1600±500C and monitored by infrared pyrometer. A holding time or soaking time of 5-10 min was allowed to the molten mass. Molten slag and metal are allowed to cool inside the furnace after completion of the reduction experiment. The metallic and non-metallic parts are physically separable and can be recovered by breaking the cakes. The metallic part is of 200- series stainless steel alloy type and its composition Si- 0.3 wt%, Fe-74.06 wt%, Cr- 12 wt%, Ni-1.5 wt%, C-3.5 wt%, Mn- 6.2 wt%. The Slag composition consists of: CaO-20.09

wt.%, MgO- 1.53 wt%, Al2O3-12.85 wt%, SiO2-19.91 wt%, MnO-30.61 wt%, FeO- 6 wt%, Cr2O3- 8.03 wt.%.
As a fourth example, 100 gm of chromite tailings, 30 gm of lime, 40 gm Mn3C and 2 gm of bentonite are blended to make the charge mix. Sufficient water was added to make the moisture 14 % followed by pelletizing. The formed pellets were oven dried at 150oC for 4 hrs post which they were charged in the submerged arc furnace. The charging of the materials and smelting experiment in arc furnace and slag metal separation were conducted in a similar manner as explained in third example. The ferrochrome alloy obtained after experiment consists of: Si-0.9 wt%, Fe-53.6 wt%, Cr-20.5 wt%, Ni-1.152 wt%, Mn-10.35 wt%, C-2.7 wt%. The Slag chemical composition consists of: CaO-24.8 wt%, MgO-2.53 wt%, Al2O3-12.5 wt%, SiO2-26.8 wt%, MnO-31.5 wt%, FeO-2 wt.%, Cr2O3- 4 wt.%.
Based on the above method, a product such as 200 series stainless steel scrap is produced where composition (in wt%) of such product includes at least of Cr: 12-20%, Si: 0.2-1.5%, C: 2.5-7%, Mn: 5-12%, Ni: 1-2%, and Fe: 65-82%.
In an embodiment, as the method steps of the present disclosure eliminates intermediate steps in production of the steel, energy consumption and emission of CO2 from such process is reduced. Thus, indicating such process to be sustainable.
In an embodiment, as the method requires low grade chromite and manganese ore for production of the steel, soil and water pollution in the environment is avoided by preventing debris of such chromite and manganese ore in landfills and other wasteyards.
In an embodiment, as 200 series stainless steel scrap is employable in wide range of industrial applications, reduction in production of such steel inherently reduces costs associated with each of the products produced from such steel. Hence, indicating a viable method for economical significance in the industrial applicability.
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, 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 description 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, 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 in the description.

We claim:
1. A method for manufacturing 200 series stainless steel scrap, the method comprising:
mixing, fine chromite tailings and a source of manganese with a powdered burden;
pelletizing, the mixture into pellets of a predefined size; and
smelting, the pellets in a submerged arc furnace to produce molten alloy and a slag over the molten alloy, wherein the molten alloy substantially includes 200 series stainless steel scrap.
2. The method as claimed in claim 1, wherein the fine chromite tailing comprises Chromium
to Iron in a ratio of 0.54 to 0.64 and chemical composition (in wt%) comprising Cr: 12-18%, Fe: 20-30%, SiO2: 20-26%, Al2O3:8-14%, Ni:0.3-0.5 %.
3. The method a claimed in claim 1, wherein the source of manganese is at least one of sub-
grade manganese ore and manganese carbide.
4. The process as claimed in claim 3, wherein the Manganese carbide containing Mn7C3: 99% by
wt.%.
5. The method as claimed in claim 3, wherein the sub-grade manganese ore contains
Manganese to Iron ratio of 0.5 to 0.8 and chemical composition (in wt%) comprising MnO: 20-28 %, Fe: 30-40%, SiO2: 3-8%, Al2O3: 2-6%, MgO: 1-3%.
6. The method as claimed in claim 3, wherein composition of the powdered burden comprises
lime, coke, and powdered bentonite, when the source of manganese is sub-grade manganese ore.
7. The method as claimed in claim 3, wherein composition of the powdered burden comprises
lime and powdered bentonite, when the source of manganese is manganese carbide.
8. The process as claimed in claims 6 and 7, wherein the coke and Manganese carbide act as a
reductant for smelting process to produce the molten alloy and the slag.
9. The method as claimed in claim 1, wherein fines of the chromite tailing and source of
manganese have size of less than 25 microns.

10. The method as claimed in claim 8, wherein the lime is powdered to include a particle size of less than 75um to blend with fines of the chromite tailing and the source of manganese.
11. The method as claimed in claim 1, wherein weight of the burden is determined based on an input basicity B and an input burden value are R (CaO+MgO/SiO2) = 0.8 to 1.2 and R (CaO+MgO/Al2O3) = 0.9-1.0, to maintain slag fluidity for separating the slag from the molten alloy.
12. The method as claimed in claim 1, wherein composition (in wt%) of the molten alloy consists at least of Fe: 65-82%, Cr: 12-20%, Si: 0.2-1.5%, C: 4.5-7%, Mn: 5-12% and Ni: 1-2%, with the sub-grade manganese ore as the source of manganese.
13. The method as claimed in claim 1, wherein composition (in wt%) of the molten alloy consists at least of Fe: 65-82%, Cr: 12-20%, Si: 0.2-1.5%, C: 2-3.5%, and Mn: 3-6Ni:0.8-2%, with manganese carbide as the source of manganese.
14. The method as claimed in claim 1, wherein composition (in wt%) of the slag includes CaO: 24-40%, MgO: 2-5%, SiO2: 30-38.4%, Al2O3: 12-19%, MnO: 5-13%, FeO: 2-5.2%, Cr2O3: 2-7%, with the sub-grade manganese ore as the source of manganese.
15. The method as claimed in claim 1, wherein composition (in wt%) of the slag includes CaO: 18-22%, MgO: 1-2%, SiO2: 15-22%, Al2O3: 10-13.5%, MnO: 28-35%, FeO: 3-6%, Cr2O3: 3-8%, with the manganese carbide as the source of manganese.
16. The method as claimed in claim 1, wherein the chromite tailings are mixed with powdered bentonite in concentration range of 1-2 wt.% and lime in concentration range of 16.5-22 wt.% for mixing and then pelletizing the mixture when the source of manganese is sub-grade manganese ore.
17. The method as claimed in claim 1, wherein the chromite tailings are mixed with powdered bentonite in concentration range of 1-3 wt.% and lime in concentration range of 18-25.72 wt.% for mixing and then pelletizing the mixture when the source of manganese is manganese carbide.

18. The method as claimed in claim 1, wherein the mixture includes a predefined quantity of water to mix the powdered burden with the fine chromite tailings and the source of manganese.
19. The method as claimed in claim 1, wherein the pellets produced by pelletizing of the mixture is dimensioned in a ranged of 8mm to 12mm.
20. The method as claimed in claim 1, wherein the arc furnace is operated with a power input between 3500 to 4000kWhr/ton of the molten alloy, during smelting process.
21. A 200 series stainless steel scrap produced by a method as claimed in claim 1, comprising a composition (in wt%) of at least of Cr: 12-20%, Si: 0.2-1.5%, C: 2.5-7%, Mn: 5-12%, Ni: 1-2%, and Fe: 65-82%.