WO2017141145A1

WO2017141145A1 - Method for pre-treatment of molten iron with special grades of iron ore

Info

Publication number: WO2017141145A1
Application number: PCT/IB2017/050768
Authority: WO
Inventors: Sabukutty DOMINIC; Mebin DOMINIC
Original assignee: Dominic Sabukutty; Dominic Mebin
Priority date: 2016-02-16
Filing date: 2017-02-11
Publication date: 2017-08-24

Abstract

The present disclosure relates to method for pre-treatment of a molten iron for removal of impurities using an iron ore, by adding the iron ore into the molten iron whereupon oxygen from the iron ore combines with the impurities and trace elements in the molten iron to form slag and thereafter removing the slag thereby obtaining relatively pure molten iron.

Description

METHOD FOR PRE- TREATMENT OF MOLTEN IRON WITH SPECIAL GRADES OF IRON ORE

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY

[001] The present application claims priority from Indian patent bearing application number 201621005447 filed on 16/02/2016

TECHNICAL FIELD

[002] The present invention relates to the field of metallurgy. Specifically, the present invention relates to the field of iron and steel making, and in particular relates to the pre- treatment of molten iron.

BACKGROUND OF THE INVENTION

[003] Presently, the most common method of steel making is by means of an integrated steel plant employing blast furnace and/or COREX units. The molten iron from the blast furnace/COREX units during the process of steel making typically has impurities such as Carbon, Silicon, Manganese, Phosphorus and other trace elements. Each of these impurities exhibit different reactivity rates with oxygen with Silicon being the most reactive and Carbon being one of the least.

[004] These impurities are removed by means of injecting oxygen through the molten iron. Pre-treatment of molten iron is carried out in most steel plants by chemical and oxygen injection, depending on the chemical composition of the molten iron. [005] The methods for pretreatment of molten iron as described in the prior art consume external energy as it involves blowing of hot air , oxygen or immersing magnesium cubes by means of a mechanical plunger. Alternatively iron ore sinter powder or iron ore fines are added in the metal runner, where the slag generated needs to be removed from the molten iron by a separate mechanism either from molten iron ladles or from the metal runner making it more expensive. The methods as described in the prior art are also time intensive.

[006] In light of the above stated discussion, there is a need for a method that overcomes the above stated disadvantages.

SUMMARY OF THE I VENTION

[007] Before the present method for pre-treatment of molten iron with special grades of iron ore is described, it is to be understood that this application is not limited to the particular system(s), and methodologies described, as there can be multiple possible embodiments which are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular implementations or versions or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to pre-treatment of molten iron with special grades of iron ore. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.

[008] Accordingly the present invention provides a method for pre- treatment of a molten iron for removal of impurities using an iron ore, by adding the iron ore into the molten iron whereupon oxygen from the iron ore combines with the impurities and trace elements in the molten iron to form slag and thereafter removing the slag thereby obtaining relatively pure molten iron.

[009] Other objectives and advantages of this invention will become apparent from the following description taken in conjunction with any accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. Any drawings contained herein constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[010] The foregoing detailed description of embodiments of pre-treatment of molten iron is better understood when read in conjunction with the appended drawings. For the purpose of illustrating of the present subject matter, an example of the method involved is provided as figures; however, the invention is not limited to the specific method and system disclosed in the document and the figures.

[011] In the detailed description, an embodiment of the method of pretreatment of molten iron to remove impurities is described in detail with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer various features of the present subject matter.

[012] Figure 1 illustrates a method for pre-treatment of molten iron to remove impurities in accordance with an embodiment of the present subject matter.

[013] It should be noted that the terms "first", "second", and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Further, the terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

DETAILED DESCRIPTION

[014] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any grade of iron ore, similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary systems and methods for pre- treatment of molten iron using special grade iron ore are now described. The disclosed embodiments for pre-treatment of molten iron using special grade iron ore are merely examples of the disclosure, which may be embodied in various forms.

[015] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments for method for pre-treatment of molten iron using special grade iron ore. However, one of ordinary skill in the art will readily recognize that the disclosure for the present invention is not intended to be limited to the embodiments described, but is to be accorded the widest scope consistent with the principles and features described herein. [016] The object of the present invention is the removal of Silicon,

Manganese, Phosphorus and other high oxygen-reactive elements from molten iron in an economic and time- efficient manner.

[017] Special grades of iron ores are typically iron ore found in lumpy form having low Tumbler index and high reducibility index. The iron ore used in the present invention should ideally have a Tumbler index between 55 and 75 and a Reducibility index above 60.

[018] The lumpy iron ore is inserted into the molten iron in front of the tap hole which leads to immediate oxidation of the impurities in order of their reactivity with oxygen starting with Silicon. The slag thus formed is removed by means of a slag runner or other conventional means.

[019] Low Tumbler index iron ore if used directly in blast furnace results in generation of fines which is not desirable. The present disclosure therefore relates to a method for an economical pre- treatment of molten iron which includes the utilization of iron ore lumps with low Tumbler index value and high reducibility.

[020] The density of iron ore falls in the range of 2.1 gm/cm³ - 2.9 gm/cm³ while the density of molten iron is in the range of 6.5gm/cm³ - 7.8 gm/cm³. The insertion of the lumpy iron ore is done such that despite a low density, the iron ore sinks in the high density molten iron stream and due to the high temperature of molten iron, melts, thereby releasing oxygen. This oxygen combines with the impurities present in the molten iron, thereby forming its oxides and this slag is removed by conventional means. [021] Referring now to Figure 1, a method for pre-treatment of molten iron for removal of impurities is disclosed. Although the present subject matter is explained considering that the iron ore 104 is added through the hopper 101 into the main runner near the tap hole , it may be understood that the pre-treatment may also be implemented in a variety of methods and with various grades of iron ore.

[022] In one implementation, the iron ore 104, of required Tumbler index and reducibility is added into the hopper 101, travels through the feeder 102, falls on the conveyor or chute mechanism 103 and is dropped into the molten iron 106 as it flows out of the blast furnace 105. The oxidation of the impurities in the molten iron results in the slag 107 and relatively pure molten iron flows past the skimmer plate 108. The relatively pure molten iron flows down the metal runner 109 while the slag is removed by conventional means such as a slag runner 110.

[023] In one embodiment, a method for pre-treatment of a molten iron for removal of impurities using an iron ore is disclosed where the method involves addition of the iron ore 104 into the molten iron 106 whereupon oxygen from the iron ore 104 combines with the impurities and trace elements in the molten iron 106 to form slag 107and thereafter removing the slag 107 thereby obtaining relatively pure molten iron.

[024] In another embodiment, the impurities may be Silicon and/or other trace elements in order of their respective oxygen potential.

[025] In one embodiment, the iron ore 104 may be in the form of lumps, briquettes or dried green pellets.

[026] In another embodiment, the Tumbler index of the iron ore 104 may be in the range of 55-75. [027] In one embodiment, the reducibility of the iron ore 104 may be above

60.

[028] In one embodiment, the iron ore 104 may be inserted via a hopper

101, a chute or a conveyor belt mechanism 103.

[029] In one embodiment, the iron ore 104 may be inserted in front of the tap hole to utilize maximum temperature of molten iron 106.

[030] In another embodiment, dephosphorisation reagents may be added at the point of addition of iron ore 104 for removal of phosphorus by maintaining slag basicity.

[031 ] In another embodiment, the slag 107 can be removed by conventional methods including a slag runner 110.

Claims

We claim:

1. A method for pre-treatment of a molten iron for removal of impurities using an iron ore, the method comprising adding the iron ore into the molten iron whereupon oxygen from the iron ore combines with the impurities and trace elements in the molten iron to form slag; removing the slag thereby obtaining relatively pure molten iron.

2. The method according to claiml, wherein the impurities may be Silicon and/or other trace elements in order of their respective oxygen potential.

3. The method according to claim 1, wherein the iron ore may be in the form of lumps, briquettes or dried green pellets.

4. The method according to claim 1 , wherein the Tumbler index of the iron ore may be in the range of 55-75.

5. The method according to claim 1, wherein the reducibility of the iron ore may be above 60.

6. The method according to claim 1, wherein the iron ore may be inserted via a hopper, a chute or a conveyor belt mechanism.

7. The method according to claim 1, wherein the iron ore may be inserted in front of the tap hole to utilize maximum temperature of molten iron.

8. The method according to claim 1 wherein dephosphorisation reagents may be added at the point of addition of iron ore for removal of phosphorus by maintaining slag basicity.

9. The method according to claim 1, wherein slag can be removed by conventional methods.