Claims:We Claim:
1. A composition for an agglomerated iron ore pellet, the agglomerated iron ore pellet comprising:
Iron ore fines: 85-95 wt%, a ferrochrome metal fine: 1-4 wt %, flux: 2-6 wt %, Coke: 1-3 wt %.
2. The composition as claimed in claim 1, wherein the ferrochrome metal fines comprises of chromium 30-61 wt%, Iron 30-70 wt% and Silicon 1.5-4 wt%.
3. The composition as claimed in claim 2, wherein the Cr/Fe ratio is in the range of 0.4 to 2.2.
4. The composition as claimed in claim 1, wherein the coke comprises of fixed carbon 82-88 wt%, volatile matter 0.5-1 wt% and ash 10-14 wt%.
5. The composition as claimed in claim 4, wherein the particle size of coke is not greater than 1mm.
6. The composition as claimed in claim 1, wherein the flux is one of lime, dolomite, hydrated lime or calcined lime.
7. The composition as claimed in claim 6, wherein the lime comprises of SiO2 1-8 wt%, MgO 0-1.5 wt%, CaO 55-68 wt% and Al2O3 <1 wt%.
8. The composition as claimed in claim 7, wherein lime maintains a basicity in the range between 0.8 to 1.2.
9. The composition as claimed in claim 1, wherein the strength of the pellets varies in the range of 164-250 kgf.
, Description:A COMPOSITION FOR AN AGGLOMERATED IRON ORE PELLET
FIELD OF INVENTION:
[001] The present subject matter described herein, relates to production of pellets from agglomerate process. The present subject matter, in particular, relates to a composition for an agglomerated iron ore pellet.
BACKGROUND AND PRIOR ART AND PROBLEM IN PRIOR ART:
[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[003] Iron ore and iron ore pellets are important sources of iron for manufacturing steel. The iron ore production has significantly expanded in recent years, owing to increasing steel demands in developing countries, such as China and India. However, the content of iron ore in deposits has deteriorated and low-grade iron ore has been processed. The fines resulting from the enrichment by separation after liberation by size reduction must be agglomerated in a pelletizing plant for further use in the steel making.
[004] The quality requirements of pellet, such as physical, chemical and metallurgical specifications, depend on each steelmaking furnace and those requirements influence the operation of the iron ore pelletizing plant.
[005] Pellets are balls formed by rolling moist concentrates and fines iron ores of different mineralogical and chemical composition, with the addition of additives and binder, in a horizontal drum or in an inclined disc.
[006] Pellets produced to be used in steelmaking processes must have characteristics that meet the list of quality specifications regarding physical, chemical, and metallurgical properties.
[007] Aiming to achieve those specifications, binders and additives are used in the pelletizing process. Additives such as limestone, dolomite, and hydrated lime are used to modify the chemical composition of the pellets, most often for correction of the basicity. Certain substances such as hydrated lime serve as both additive and binder. Fines of anthracite or coke are also added during the pelletizing process for reducing the consumption of fuel required for internally heating the ball.
[008] Pellets are obtained by adding an appropriate amount of water to the iron ore concentrate. This is a fundamental factor in the formation and growth of pellets, which creates a surface tension that holds the mineral grains cohesive, thus allowing their handling. When the pellet is heated, the vaporization of water occurs and the pellets tend to disintegrate.
[009] To avoid such effects, binders are added to the material to be pelletized, aiming to:
• increase the strength of pellets before heating (green strength);
• prevent the collapse of pellets during the initial stages of heating, when a large volume of gas generated by water vaporization tends to crack the pellets.
[0010] Evenly distributed moisture and binder in the feeding process is decisive to improve the characteristics of pellets, especially to avoid the formation of undesirable agglomerates before the pellet formation. Bentonite is an effective, widely used binder in the iron ore pelletizing process. Its low price is an important factor for its extensive use.
[0011] However, bentonite incorporates silica and alumina, which are undesirable contaminants to pellets. Additionally, it is a natural material with variable composition depending on its origin. Obtaining a suitable binding effect requires a relatively large amount of material, around 0.5% by weight, which makes handling more difficult and increases logistics costs.
[0012] Further, Ferrochrome is a ferroalloy used chiefly in steel making. The handling and manual breaking of ferrochrome metal, results in the formation of fines which goes unutilized. If not huge, it is a significant loss to the metal industry. The fines collected can’t be directly fed in the steel making furnace nor can they be agglomerated. The iron and steel plants uses different binders for making pellets and briquettes. Most of the binder weather organic or inorganic reports to the slag and adds to the slag volume apart from getting volatilized.
[0013] French patent 1,223,202 describes the use of metallic aluminium which is added to Aluminium nitride powder with sodium silicate, gum Arabic, or ceresin before shaping and pressing the pieces. The metallic Aluminium is used as Aluminium nitride has high sintering temperature and other binders are not suitable for binding purpose.
[0014] US patent 3,001,238 describes the use of low melting metals or alloys to bond powdered magnetic metals, such as alnico. A mixture is prepared with the powder, fusible metal and zinc chloride (acting as a flux). The mixture is then heated which in turn coats the alnico grains, followed by pressing into the mould at a temperature above the melting point of the binder and then cooling it.
[0015] Another US patent 3,030,216 refers to the use of chromium compounds or ores as binders for dead-burned magnesite, primarily to improve the strength of such materials.
[0016] US patent 2,866,698 uses a mixture of special type of glass and metallic portion containing iron carbonyl, tungsten carbide, copper and small amount of manganese and graphite to bind diamond abrasive.
[0017] However, none of the specified references discuss about the use of ferrochrome metal fines as a binder for ores. These fines are either unutilized or are sold at cheaper rates than metal. In literature, there is no such comprehensive process to utilize these fines.
[0018] The present subject matter describes the composition of iron ore pellets comprising of ferrochrome metal fines as a binder.
OBJECTS OF THE INVENTION:
[0019] It is therefore the object of the invention to overcome the aforementioned and other drawbacks in prior method/product/apparatus.
[001] The principal objective of the present invention is to utilize metal fines generated during the manual breaking of ferrochrome metal to produce agglomerated iron ore pellets.
[002] Another object of the present invention is to develop a composition of iron ore pellets comprising of ferrochrome metal fines as a binder.
[003] Another object of the present invention is to develop a ferrochrome metal fines to replace the traditional organic binders, which are only meant for imparting strength.
[004] Yet another object of the present invention is to develop agglomerated iron ore pellet using ferrochrome metal fines as binder with strength comparable to the agglomerated iron ore pellet using bentonite as a binder.
[005] Still yet another object of the present invention is to develop an agglomerated iron ore pellet in which decreases the slag while production of steel.
[006] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION:
[007] Solution to one or more drawbacks of conventional agglomerated iron ore pellet using organic binders, and additional advantages are provided through the agglomerated iron ore pellet as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.
[008] The present subject matter relates to a composition for an agglomerated iron ore pellet.
[009] In an embodiment, the present subject matter discloses a composition for an agglomerated iron ore pellet comprising Iron ore fines: 85-95 wt%, a ferrochrome metal fine: 1-4 wt %, flux: 2-6 wt %, Coke: 1-3 wt %.
[0010] In an aspect, the ferrochrome metal fines comprises of chromium 30-61 wt%, Iron 30-70 wt% and Silicon 1.5-4 wt%.
[0011] In an aspect, the Cr/Fe ratio is in the range of 0.4 to 2.2.
[0012] In an aspect, the coke comprises of fixed carbon 82-88 wt%, volatile matter 0.5-1 wt% and ash 10-14 wt%.
[0013] In an aspect, the particle size of coke is not greater than 1mm.
[0014] In an aspect, the flux is one of lime, dolomite, hydrated lime or calcined lime.
[0015] In an aspect, the lime comprises of SiO2 1-8 wt%, MgO 0-1.5 wt%, CaO 55-68 wt% and Al2O3 <1 wt%.
[0016] In an aspect, lime maintains a basicity in the range between 0.8 to 1.2.
[0017] In an aspect, the strength of the pellets varies in the range of 164-250 kgf.
[0018] 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.
[0019] 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 DRAWINGS
[0020] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0021] Fig. 1 illustrates a flow diagram of preparation of agglomerated iron ore pellet using ferrochrome metal fines binder.
[0022] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily 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.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0023] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0024] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[0025] The present subject matter relates to composition for an agglomerated iron ore pellet using ferrochrome metal fine as a binder.
[0026] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that 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 subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, 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.
[0027] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0028] Referring to Figure 1, illustrating flow diagram of preparation of agglomerated iron ore pellet using ferrochrome metal fines binder. The agglomerated iron ore pellet comprises Iron ore fines, a ferrochrome metal fine as a binder, flux and Coke.
[0029] The iron ore fines are taken as a primary constituent in the range 85-95 wt%. Carbon is added in the iron ore fines in the range 1-3 wt %. Carbon can be added in the form of coal or coke or any other carbonaceous material. Preferably, coke is used as a carbonaceous material containing fixed carbon in the range of 82-88%. The volatile matter present in the coke is in the range 0.5-1% and ash in the range 10-14%. The particle size of the coke is preferably varied from anywhere to less than 1mm.
[0030] The required initial plasticity is provided to the mixture of iron ore fines and coke by introducing flux in 2-6 wt %. The flux is introduced either in the form of lime, dolomite, hydrated lime or calcined lime. Preferably, the hydrated lime is used for the slag formation and to maintain the proper basicity (0.8-1.2) having CaO in the range of 55-68% with MgO (1-8%), SiO2 (1-8%).
[0031] Binding of the iron ore, coke and flux is done through ferrochrome metal fines, which are byproduct generated during the manual breaking of ferrochrome metal prepared to produce steel. The content of ferrochrome metal fines varied between 1% - 3% in the agglomerated iron ore pellet. The ferrochrome metal fines chiefly contain iron, chromium, carbon and silicon. The ferrochrome metal fines contain Chromium in the range of 30-61 % with Iron (30-70 %), Silicon (1.5-4 %) and Cr/Fe ration in the range of 0.4-2.2.
[0032] Table 1 below shows chemical composition of raw material (wt %):
Table 1
Constituents Ferrochrome Metal Fines Coke Lime
Cr 30-61
Fe(T) 30-70
SiO2 1.5-4 6-10 1-8
MgO <1 0-1.5
CaO <1.5 55-68
Al2O3 <1
FC 5-7 80-87

[0033] All the components i.e. Iron ore fines, ferrochrome metal fine, flux and Coke are mixed with each other in their respective configuration 85-95 wt%, 1-4 wt %, 2-6 wt % and 1-3 wt %, respectively, and formed into pellets. The moisture in the pellets varies from 8-15%. The pellets were then oven dried and fired in the muffle furnace. After firing the pellets are tested for their strength. The strength of the pellets varied in the range of 164-250 kgf. While the green strength varied between 1.7-2.5 kgf. The observed strength was comparable to that when bentonite was used as a binder.
[0034] Table 2 shows the strength comparison of pellets with metal as a binder to pellet with bentonite.
Table 2
Binder Before firing strength (kgf) After Firing strength (kgf)
Metal powder 1.7-2.5 164-250
Bentonite 2.11-2.8 166-276

EXPERIMENT 1
[0035] To test the composition disclosed above, 5 kg iron ore fines, 100gm coke, 100 gm lime and 100 gm metal powder were blended to make the charge mix. Sufficient water was added to achieve a moisture of 12% followed by pelletizing in the disc pelletizer. The strength of the pellets was measured before and after firing to 1300oC. During firing the samples were held at 1300oC for 2 hrs. During experiment the operation temperature was monitored by pyrometer. The samples were allowed to furnace cool. The strength of the pellet obtained in this case was found to be of 2.4 kgf strength before firing and after firing the strength was found to be 235 kgf.
EXPERIMENT 2
[0036] In further experiment, 5 kg iron ore fines, 100 gm coke, 100 gm lime and 150 gm metal powder were blended to make the charge mix. Sufficient water was added to achieve a moisture of 14% followed by pelletizing in the disc pelletizer. The strength of the pellets was measured before and after firing of the pellets to 1300oC. Remaining procedure was similar to that in Experiment one. The strength of the pellet obtained before firing was found to be 1.8 kgf and after firing was found to be 190 kgf.
[0037] As evident from the experiment, the agglomerated iron ore pellet produced by using ferrochrome metal fines as binder has strength comparable to the strength of agglomerated iron ore pellet produced using bentonite as binder. Further, the slag formation in case of using ferrochrome metal fines as binder is low when compared to slag formation in case of using bentonite as binder.
[0038] 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.”
[0039] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0040] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.