US20160333431A1

US20160333431A1 - Use of ladle furnace slag from al-killed steel in si-killed steelmaking as calcium aluminate flux

Info

Publication number: US20160333431A1
Application number: US15/111,100
Authority: US
Inventors: Narottam Behera
Original assignee: Saudi Basic Industries Corp
Current assignee: Saudi Basic Industries Corp
Priority date: 2014-01-31
Filing date: 2015-01-28
Publication date: 2016-11-17
Also published as: CN105940121A; WO2015114545A1; EP3099825A1

Abstract

The present disclosures and inventions relate to a method for producing Si-killed steel comprising: a) supplying Al-killed steel ladle furnace slag; and b) adding the Al-killed steel ladle furnace slag to a Si-killed steel process to thereby produce Si-killed steel.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Application No. 61/934,320 filed Jan. 31, 2014, which is hereby incorporated by reference in its entirety.

BACKGROUND

Part of the steel making process involves producing a steel slag, which is conventionally a by-product. Generating the steel slag allows for the removal of unwanted substances by forming complexes with metal and nonmetal oxides. Conventionally, fluorspar (calcium fluoride) is used for slag fluidity, but it has a corrosive effect on the ladle refractory and is environmentally harmful. The conventional alternative, calcium aluminate synthetic slag, is very effective in slag fluxing, but it is cost prohibitive.
Accordingly, there is a growing need for materials for use in the steel process that provide slag fluidity, while being cost effective, noncorrosive, and less environmentally harmful.

SUMMARY

In accordance with the purpose(s) of the invention, as embodied and broadly described herein, the invention, in one aspect, relates to a method for producing Si-killed steel comprising:

- a) supplying Al-killed steel ladle furnace slag; and
- b) adding the Al-killed steel ladle furnace slag to a Si-killed steel process to thereby produce Si-killed steel.

Disclosed are methods for producing Si-killed steel comprising:

- a) supplying Al-killed steel ladle furnace slag comprising silica dioxide in an amount ranging from 1 wt % to 8 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag and aluminum oxide in an amount ranging from 15 wt % to 50 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag;
- b) adding the Al-killed steel ladle furnace slag to a Si-killed steel process to thereby produce Si-killed steel;
wherein the Al-killed steel ladle furnace slag is added at a ladle step, wherein the ladle step is at a temperature ranging from 1500° C. to 1700° C.; and
wherein the method comprises a billet caster step after the ladle step.

While aspects of the present invention can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present invention can be described and claimed in any statutory class. Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several aspects and together with the description serve to explain the principles of the invention.

FIG. 1 shows a conventional steel making process for aluminum killed steel and silicon killed steel.

FIG. 2 shows a graph depicting x-ray fluorescence (XRF) chemical analysis of Si-killed steel ladle slag, Al-killed steel ladle slag, and calcium aluminate flux.

FIG. 3 shows a scanning electron microscope (SEM) micrograph of Si-killed ladle slag according to the present invention.

FIG. 4 shows a scanning electron microscope (SEM) micrograph of Si-killed ladle slag according to the present invention.

FIG. 5 shows a scanning electron microscope (SEM) micrograph of Al-killed ladle slag according to the present invention.

FIG. 6 shows a scanning electron microscope (SEM) micrograph of Al-killed ladle slag according to the present invention.

FIG. 7 shows a scanning electron microscope (SEM) micrograph of calcium aluminate flux according to the present invention.

FIG. 8 shows a scanning electron microscope (SEM) micrograph of calcium aluminate flux according to the present invention.

Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DESCRIPTION

The present invention can be understood more readily by reference to the following detailed description of the invention and the Examples included therein.
Before the present compounds, compositions, articles, systems, devices, and/or methods are disclosed and described, it is to be understood that they are not limited to specific synthetic methods unless otherwise specified, or to particular reagents unless otherwise specified, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, example methods and materials are now described.
All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided herein can be different from the actual publication dates, which can require independent confirmation.

A. DEFINITIONS

As used herein, nomenclature for compounds, including organic compounds, can be given using common names, IUPAC, IUBMB, or CAS recommendations for nomenclature. When one or more stereochemical features are present, Cahn-Ingold-Prelog rules for stereochemistry can be employed to designate stereochemical priority, E/Z specification, and the like. One of skill in the art can readily ascertain the structure of a compound if given a name, either by systemic reduction of the compound structure using naming conventions, or by commercially available software, such as CHEMDRAW™ (Cambridgesoft Corporation, U.S.A.).
As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a functional group,” “an alkyl,” or “a residue” includes mixtures of two or more such functional groups, alkyls, or residues, and the like.
Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, a further aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms a further aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.
References in the specification and concluding claims to parts by weight of a particular element or component in a composition denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound.
A weight percent (wt. %) of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.
As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or can not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; and the number or type of embodiments described in the specification.
Disclosed are the components to be used to prepare the compositions of the invention as well as the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds can not be explicitly disclosed, each is specifically contemplated and described herein. For example, if a particular compound is disclosed and discussed and a number of modifications that can be made to a number of molecules including the compounds are discussed, specifically contemplated is each and every combination and permutation of the compound and the modifications that are possible unless specifically indicated to the contrary. Thus, if a class of molecules A, B, and C are disclosed as well as a class of molecules D, E, and F and an example of a combination molecule, A-D is disclosed, then even if each is not individually recited each is individually and collectively contemplated meaning combinations, A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are considered disclosed. Likewise, any subset or combination of these is also disclosed. Thus, for example, the sub-group of A-E, B-F, and C-E would be considered disclosed. This concept applies to all aspects of this application including, but not limited to, steps in methods of making and using the compositions of the invention. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the methods of the invention.
As used herein, the term “direct reduction process of natural iron ores” refers to a process of reducing natural iron ores to a metallic iron at the temperatures below the melting point of iron (800-1050° C.), in the presence of reducing gases or coal. For example and without limitations, in some aspects of the invention, for exemplary purposes, the reducing gases can comprise a hydrogen gas (H₂), a carbon monoxide gas (CO), or hydrocarbon-rich gases, or any mixture thereof. In one aspect, the product of such solid state process is called a direct reduced iron (DRI).
As used herein, the term “slag” refers to a by-product of the steelmaking process, which separates the desired metal fraction from the unwanted fraction.
As used herein, the terms “Al-killed steel ladle furnace slag,” “aluminum killed slag,” “aluminum killed steel slag,” and “Al-killed slag” are used interchangeably and refers to the slag produced by the aluminum killed steel making process. In an Al-killed steel making process, steel is deoxidized with aluminum in order to reduce the oxygen content to a minimum so that no reaction or substantially no reactions occur between carbon and oxygen during the solidification. The dissolved oxygen levels are from 1 to 20 ppm in the product; which is commonly known as a flat steel product.
As used herein, the terms “Si-killed steel ladle furnace slag,” “silica killed slag,” “silica killed steel slag,” and “Si-killed slag” are used interchangeably and refers to the slag produced by the silica killed steel making process. In a Si-killed steel making process, steel is deoxidized with ferrosilicon and is used for incompletely deoxidized steels containing 20 to 50 ppm of oxygen. The product is also known as a long steel product.
As used herein, the term “killed steel” refers to steel that has been treated to substantially or fully deoxidize the steel during the casting process.
It is understood that the compositions disclosed herein have certain functions. Disclosed herein are certain structural requirements for performing the disclosed functions, and it is understood that there are a variety of structures that can perform the same function that are related to the disclosed structures, and that these structures will typically achieve the same result.

B. METHODS

Disclosed herein are methods for producing Si-killed steel comprising:

In another aspect, disclosed herein are methods for producing Si-killed steel comprising:

1. Overall Steel Making Process
In one aspect, the underlying steel making process comprises the same or similar steps as in the steel making process utilizing a conventional electric arc furnace (EAF). In various aspects of this invention, the electric arc furnace is used for melting materials that have been fed into the furnace. In one aspect, and as one of ordinary skill in the art would appreciate, the energy required for melting in the electric arc furnace, is introduced by means of an electric current via one or more electrodes, and the heat is transferred to the metallic charge via an electric arc. In various aspects of the invention, the materials fed into the electric arc furnace have to avoid contact with the electrodes and damage the same when charging the furnace.
In another aspect, these steps comprise a melting step, a refining step, and a tapping step. In a further aspect, the steel making process comprises liquefying the steel, the tapping in the ladle, and transferring to the ladle processing station. In an even further aspect, the steel making process comprises the process parameters as used in the conventional electric arc furnace (EAF), such as temperature, residence time, reactors, pressure, and additional ingredients, when using direct reduced iron at 80 wt % and scrap at 20 wt %. In one aspect, the scrap can be EAF dust.
The steel making process can follow an aluminum killed route or a silicon killed route as shown in FIG. 1. As shown in FIG. 1, the aluminum killed route proceeds to slab casting. Further as shown in FIG. 1, the silicon killed route proceeds to billet casting. FIG. 1 illustrates that both routes start with the raw material, then proceed to the direct reduction, then proceed to the steelmaking, and then to the ladle treatment.
Liquid steels contain dissolved oxygen after their conversion from molten iron. Therefore, several strategies have been developed for deoxidation based on the final product requirement. According to the degree of deoxidation, carbon steels may be subdivided into three groups: (1) killed steel, (2) semi-killed and (3) rimming steel. Killed steel is free from oxygen, semi-killed steel is incompletely deoxidized steels containing some amount of oxygen, and rimming steel is partially deoxidized or nondeoxidized steel.
2. Ladle Treatment Step
In one aspect, the Al-killed steel ladle furnace slag is added at a ladle step in the Si-killed steel process. In another aspect, the ladle step comprises heating, desulfurization, alloying, and/or rinsing. In a further aspect, the ladle treatment step can be used for desulfurization, homogenization of temperature, and/or to adjust the chemical composition for casting.
A ladle step in the steel making process serves to refine the steel. For example, unwanted impurities can be removed and the steel can be homogenized. A ladle step can comprise heating liquid steel by the use of graphite electrodes, which are operated by electricity. Homogenization of the steel temperature and chemistry can be achieved by use of inert gas which is stirred with the liquid steel. The production of alloys can also be achieved through bulk or trim chemical control. The ladle step can also be used for desulfurization of the steel. The ladle step acts as a buffer for downstream steelmaking equipment. As such, the addition of the Al-killed steel ladle furnace slag to the Si-killed steel process during the ladle step promotes the refinement of the final product, Si-killed steel. The composition of Al-killed steel ladle furnace slag has beneficial properties for the Si-killed steel process. For example, according to various aspects, the Al-killed steel ladle furnace slag can act as a calcium aluminate flux to reduce the consumption of lime and deoxidizer, and to promote non-metallic inclusion absorption and ladle refractory protection. In one aspect, the Al-killed steel ladle furnace slag can be a substitute for calcium aluminate flux or lime. In a further aspect, the Al-killed steel ladle furnace slag can replace some of or all of calcium aluminate flux or lime.
In another aspect, the Al-killed slag is added at the same time as the lime to the ladle step. In a further aspect, the Al-killed slag and lime are added after 20 wt % to 25 wt % of the total amount of the liquid steel has been added to the ladle, including exemplary values of 21 wt %, 22 wt %, 23 wt %, and 24 wt %. In another aspect, the range can be derived from any two exemplary values. For example, the Al-killed slag and lime are added after 21 wt % to 25 wt % of the total amount of the liquid steel has been added to the ladle.
In one aspect, the ladle step comprises desulfurization of the Al-killed steel ladle furnace slag.
In a further aspect, the ladle step has a residence time in an amount ranging from 25 min to 50 min after the tapping step, including exemplary values of 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min, 40 min, 41 min, 42 min, 43 min, 44 min, 45 min, 46 min, 47 min, 48 min, and 49 min In another aspect, the range can be derived from any two exemplary values. For example, the ladle step can have a residence time in an amount ranging from 30 minutes to 45 minutes after the tapping step.
After the ladle step, the process continues to the billet caster step.
In a further aspect, step (b) comprises adding the Al-killed steel ladle furnace slag to a ladle, in the Si-killed steel process wherein the ladle is at a temperature ranging from 1500° C. to 1700° C., including exemplary values 1510° C., 1520° C., 1530° C., 1540° C., 1550° C., 1560° C., 1570° C., 1580° C., 1590° C., 1600° C., 1610° C., 1620° C., 1630° C., 1640° C., 1650° C., 1660° C., 1670° C., 1680° C., and 1690° C. In another aspect, the range can be derived from any two exemplary values. For example, the temperature ranges from 1510° C. to 1690° C.
In one aspect, the Al-killed slag is added to the ladle at atmospheric pressure.
3. Tapping Step
In one aspect, the ladle step comprises a tapping step. In one aspect, the Al-killed slag should be added at the time of tapping for proper mixing.
The tapping step occurs once the desired steel composition and temperature are achieved in the electric arc furnace, then the tap-hole is opened, the furnace is tilted, and the steel pours into a ladle for transfer to the next batch operation (usually a ladle furnace or ladle station).
4. Casting
In one aspect, the method comprises a billet caster step after the ladle step.
In another aspect, the method does not comprise a slab casting step. As such, in that aspect, the method does not comprise producing a flat product, such as a hot rolled coil and/or plate.
In a further aspect, the billet caster step can produce the steel as a long product. In one aspect, the billet caster step can produce the steel as a bar, rod, wire, and/or beam. In another aspect, the size of the billet cross section produced by the billet caster can vary from 100×100 mm to 250×250 mm
Conventionally, Al-killed steel is cast in a slab caster whereas Si-killed steel is cast in a billet caster. This difference in casting is illustrated in FIG. 1.
5. Aluminum-Killed Steel Slag and Silica-Killed Steel Slag
Aluminum is typically added at a tapping stage to deoxidize steel in order to reduce the oxygen content and forms Al₂O₃(Alumina) slag.
Ferrosilicon and silicomanganese are typically added at a tapping stage to deoxidize steel in order to reduce the oxygen content and form SiO₂(silica) slag.
In one aspect, the steel making process involves removing the slag. The slag can have a lower density than the liquid steel. As such, the slag can float on top of the liquid steel. In a further aspect, the slag floats in the steel ladle and remains in the ladle. In a yet further aspect, the slag can be removed prior to the casting from the ladle.
In one aspect, the slag is collected in a slag pot. In a further aspect, the slag pot can comprise any desired type of slag pot, such as, for example, a cast steel slag pot or cast iron slag pot. In a still further aspect, cast steel slag pots generally have higher ductility, impact resistance and weld-ability. As such, cast steel slag pots are less likely to be damaged and are easy to repair. In another aspect, cast iron slag pots exhibit less slag adherence to the pot wall and bottom due to favorable heat conductivity. In some aspects, the slag pot is a cast steel slag pot. In other aspects, the slag pot is a cast iron slag pot.
In one aspect, the method does not comprise the use of and/or adding fluorspar (calcium fluoride). Avoiding calcium fluoride makes the method less corrosive and less environmentally harmful, when compared to a method that uses calcium fluoride. In one aspect, the method does not comprise the use of and/or adding bauxite. Bauxite is a principal ore of aluminum, largely composed of a mixture of hydrous aluminum oxides. In one aspect, the method does not comprise the use of and/or adding calcium aluminate synthetic slag. Calcium aluminate for synthetic slag is made of calcium and aluminate, blended at a proper proportion, ground to powder, pelletized and sintered. In a further aspect, the process does not use calcium aluminate synthetic slag.
In another aspect, the process prepares calcium aluminate, along with the aluminum killed slag. In a further aspect, the calcium aluminate is not completely replaced by the aluminum killed slag. Typically, calcium fluoride/bauxite/calcium aluminate synthetic slag are added in a tapping stage to make the slag fluid and improve desulfurization. In a Si-killed steel process, according to various aspects, Al-killed slag can be more useful than calcium aluminate due to lower wt % of Al₂O₃(15-50%) and higher wt % of CaO (40-60%). For example, in a further aspect, the higher amount of Al₂O₃(30-60%) in calcium aluminate flux can cause nozzle clogging in the caster.
In one aspect, the Al-killed slag partially or wholly replaces fluorspar, calcium aluminate synthetic slag, and/or bauxite. The Al-killed slag can provide a material advantage over fluorspar, calcium aluminate synthetic slag, and/or bauxite by being low-cost, noncorrosive, and less environmentally harmful.
In one aspect, the aluminum killed slag comprises calcium and alumina. The calcium and alumina can form the slag fluid and improve the reaction rate and/or reduce the calcium oxide (lime) consumption.
In a further aspect, using the aluminum killed slag reduces economic costs because the aluminum killed slag is a by-product of the aluminum killed steel making process. Further, using the aluminum killed slag can reduce environmental hazards and waste because the aluminum killed slag is reused and/or recycled.
In one aspect, the Al-killed steel ladle furnace slag has an oxygen potential equilibrium ranging from 1 ppm to 20 ppm, including exemplary values 2 ppm, 3 ppm, 4 ppm, 5 ppm, 6 ppm, 7 ppm, 8 ppm, 9 ppm, 10 ppm, 11 ppm, 12 ppm, 13 ppm, 14 ppm, 15 ppm, 16 ppm, 17 ppm, 18 ppm, and 19 ppm. In another aspect, the range can be derived from any two exemplary values. In another aspect, the range can be derived from any two exemplary values. For example, the oxygen potential equilibrium can range from 2 ppm to 20 ppm. Further for example, the oxygen potential equilibrium of Al-killed slag has a 5 ppm with Al-killed steel. Even further for example, the oxygen potential equilibrium of Si-killed slag has a 25 ppm with Si-killed steel.
In one aspect, the Al-killed steel ladle furnace slag comprises lime in an amount ranging from 40% by weight to 80% by weight based on the total Al-killed steel ladle furnace slag, including exemplary values of 45% by weight, 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, and 75% by weight. In another aspect, the range can be derived from any two exemplary values. For example, the range can be from 45% by weight to 75% by weight, or 40% by weight to 60% by weight.
In one aspect, the Al-killed steel ladle furnace slag comprises silica dioxide in an amount ranging from 1 wt % to 15 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag, including exemplary values of 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, and 14 wt %. In another aspect, the range can be derived from any two exemplary values. For example, the Al-killed steel ladle furnace slag can comprise silica dioxide in an amount ranging from 1 wt % to 8 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag.
In one aspect, the Al-killed steel ladle furnace slag comprises aluminum oxide in an amount ranging from 15 wt % to 50 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag, including exemplary values of 16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt %, 21 wt %, 22 wt %, 23 wt %, 24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt %, 29 wt %, 30 wt %, 31 wt %, 32 wt %, 33 wt %, 34 wt %, 35 wt %, 36 wt %, 37 wt %, 38 wt %, 39 wt %, 40 wt %, 41 wt %, 42 wt %, 43 wt %, 44 wt %, 45 wt %, 46 wt %, 47 wt %, 48 wt %, and 49 wt %. In another aspect, the range can be derived from any two exemplary values. For example, the Al-killed steel ladle furnace slag comprises aluminum oxide in an amount ranging from 20 wt % to 30 wt %, or from 15 wt % to 45 wt %, or from 25 wt % to 45 wt %, or from 30 wt % to 40 wt % based on the total weight percentage of the Al-killed steel ladle furnace slag.
In one aspect, Al-killed slag can comprise from greater than 0 wt % to 10 wt % MgO, which can protect the refractory erosion. For example, Al-killed slag can comprise from 5 wt % to 10 wt % MgO, such as, for example, 8 wt % MgO.
In one aspect, Al-killed slag can comprise from greater than 0 wt % to 5 wt % MnO, which can protect the refractory erosion. For example, Al-killed slag can comprise from 0.5 wt % to 1.5 wt % MnO, such as, for example, 1 wt % MnO.
As can be seen below in Table 1, the silica-killed slag and the aluminum-killed slag have different chemical compositions. Table 1 shows an example of the approximate composition of the silica-killed slag and the aluminum-killed slag.

TABLE 1

Approximate compositions for aluminum killed
slag and silica killed slag can be:

	FeO	SiO₂	Al₂O₃	CaO	MgO	MnO
Slag Type	(wt %)	(wt %)	(wt %)	(wt %)	(wt %)	(wt %)

Si-killed slag	1-2	20-30	5-10	45-55	5-7	0.5-1.5
Al-killed slag	1-3	1-8	15-50	40-60	5-10	0.5-1.5

As can be seen below in Table 2, the silica-killed steel and the aluminum-killed steel have different chemical compositions. Table 2 shows an example of the approximate compositions of the silica-killed steel and the aluminum-killed steel.

TABLE 2

Approximate compositions for conventional aluminum killed steel
and silica killed steel aside from iron which constitutes the
balance of the aluminum killed steel or silica killed steel

	Si (not				Al (wt %)
C	oxide form)	Mn	P	S	(not oxide	N
(wt %)	(wt %)	(wt %)	(wt %)	(wt %)	form)	(ppm)

Si-killed steel	0.15-0.25	0.2-0.3	0.8-1	0-0.05	0-0.05	0-0.005	150
Al-killed steel	0.05-0.08	0.02-0.05	0.2-0.8	0-0.02	0-0.02	0.03-0.06	40-80

Table 3 shows an example of the approximate compositions of the silica-killed steel with Al-killed slag aside from iron which constitutes the balance of the table.

TABLE 3

	Si (not				Al (wt %)
C	oxide form)	Mn	P	S	(not oxide	Cu	N
(wt %)	(wt %)	(wt %)	(wt %)	(wt %)	form)	(wt %)	(ppm)

0.20-0.30	0.15-0.30	0.50-1.00	0.03-0.05	0.03-0.05	0.001-0.005	0.15-0.30	60-150

In one aspect, the different steels produced by the Al-killed slag and the Si-killed slag, as shown in Table 2, differ in their chemical compositions. For example, the Al-killed steel can be a deoxidizer compared to silica and/or manganese. As such, the different steels produced by the Al-killed slag and the Si-killed slag have different chemical and mechanical properties.
It is understood that the disclosed articles of manufacture can be made by the disclosed methods.

C. ARTICLE OF MANUFACTURE

In one aspect, there is an article of manufacture comprising Si-killed steel produced using Al-killed steel ladle furnace slag, wherein the article is a long product.
In one aspect, the long product comprises a bar, a rod, a wire, or a beam. Such articles can be used in construction and structural applications.
In another aspect, the long product does not comprise a flat product. In a further aspect, the long product was not produced by slab casting.
It is also understood that the disclosed methods can be employed to make the articles of manufacture.
Optionally, in various aspects, the disclosed methods can be operated or performed on an industrial scale. In one aspect, the methods disclosed herein can be configured to produce steel on an industrial scale. For example, according to further aspects, the methods can produce batches of steel on an industrial scale. In a further aspect, the batch size can comprise any desired industrial-scale batch size.
In one aspect, the batch size can optionally be at least about 1 kg, including exemplary batch sizes of at least about 10 kg, at least about 25 kg, at least about 50 kg, at least about 100 kg, at least about 250 kg, at least about 500 kg, at least about 750 kg, at least about 1,000 kg, at least about 2,500 kg, or greater. In an additional aspect, the batch size can optionally range from about 1 kg to about 2,500 kg, such as, for example, from about 10 kg to about 1,000 kg, from about 1,000 kg to about 2,500 kg, from about 100 kg to about 500 kg, from about 500 kg to about 1,000 kg, from about 10 kg to about 100 kg, from about 100 kg to about 250 kg, from about 500 kg to about 750 kg, or from about 750 kg to about 1,000 kg.
In another aspect, the batch size can optionally be at least about 1 ton, including exemplary batch sizes of at least about 10 tons, at least about 25 tons, at least about 50 tons, at least about 100 tons, at least about 250 tons, at least about 500 tons, at least about 750 tons, at least about 1000 tons, at least about 2,500 tons, or greater. In an additional aspect, the batch size can optionally range from about 1 ton to about 2,500 tons, such as, for example, from about 10 tons to about 1,000 tons, from about 1,000 tons to about 2,500 tons, from about 100 tons to about 500 tons, from about 500 tons to about 1,000 tons, from about 10 tons to about 100 tons, from about 100 tons to about 250 tons, from about 500 tons to about 750 tons, or from about 750 tons to about 1,000 tons.
In various aspects, the disclosed methods can be operated or performed on any desired time scale or production schedule that is commercially practicable. In one aspect, the disclosed methods can produce a quantity of at least 1 ton of steel in a period of 1 day or less, including exemplary quantities of at least about 10 tons, 100 tons, 500 tons, or 1,000 tons, or greater within the period. In a further aspect, the period of time can be 1 hour. In a still further aspect, the quantity of steel produced can range from about 1 ton to about 1,000 tons, and the period of time can range from about 1 hour to about 1 year, for example, about 10 to about 1,000 tons in a period of about 1 hour to about 1 day.

D. ASPECTS

The disclosed methods and articles include at least the following aspects.
Aspect 1: A method for producing Si-killed steel comprising:

Aspect 2: The method according to aspect 1, wherein the Al-killed steel ladle furnace slag comprises silica dioxide in an amount ranging from 1 wt % to 15 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag.
Aspect 3: The method according to any one of aspects 1-2, wherein the Al-killed steel ladle furnace slag comprises silica dioxide in an amount ranging from 1 wt % to 8 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag.
Aspect 4: The method according to any one of aspects 1-3, wherein the Al-killed steel ladle furnace slag comprises aluminum oxide in an amount ranging from 15 wt % to 50 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag.
Aspect 5: The method according to any one of aspects 1-4, wherein the Al-killed steel ladle furnace slag comprises aluminum oxide in an amount ranging from 25 wt % to 45 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag.
Aspect 6: The method according to any one of aspects 1-5, wherein the method does not comprise adding calcium fluoride.
Aspect 7: The method according to any one of aspects 1-6, wherein the Al-killed steel ladle furnace slag has an oxygen potential equilibrium ranging from 1 ppm to 20 ppm.
Aspect 8: The method according to any one of aspects 1-7, wherein the Al-killed steel ladle furnace slag comprises lime in an amount ranging from 40% by weight to 80% by weight based on the total Al-killed steel ladle furnace slag.
Aspect 9: The method according to any one of aspects 1-8, wherein the Al-killed steel ladle furnace slag is added at a ladle step.
Aspect 10: The method according to aspect 9, wherein the ladle step comprises a tapping step.
Aspect 11: The method according to aspect 10, wherein the ladle step has a residence time in an amount ranging from 25 minutes to 50 minutes after the tapping step.
Aspect 12: The method according to any one of aspects 9-11, wherein the method comprises a billet caster step after the ladle step.
Aspect 13: The method according to any one of aspects 9-12, wherein the ladle step comprises desulfurization of the Al-killed steel ladle furnace slag.
Aspect 14: The method according to any one of aspects 1-13, wherein step (b) comprises adding the Al-killed steel ladle furnace slag to a ladle, wherein the ladle is at a temperature ranging from 1500° C. to 1700° C.
Aspect 15: The method according to any one of aspects 1-14, wherein the method does not comprise a slab casting step.
Aspect 16: The method according to any one of aspects 1-15, wherein the method does not comprise adding calcium aluminate synthetic slag.
Aspect 17: An article of manufacture comprising Si-killed steel produced using Al-killed steel ladle furnace slag, wherein the article is a long product.
Aspect 18: The article of manufacture according to aspect 17, wherein the long product comprises a bar, a rod, a wire, or a beam.
Aspect 19: The article of manufacture according to aspect 17, wherein the long product does not comprise a flat product.
Aspect 20: A method for producing Si-killed steel comprising:

- a) supplying Al-killed steel ladle furnace slag comprising silica dioxide in an amount ranging from 1 wt % to 8 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag and aluminum oxide in an amount ranging from 15 wt % to 50 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag;
- b) adding the Al-killed steel ladle furnace slag to a Si-killed steel process to thereby produce Si-killed steel;
  - wherein the Al-killed steel ladle furnace slag is added at a ladle step, wherein the ladle step is at a temperature ranging from 1500° C. to 1700° C.; and
  - wherein the method comprises a billet caster step after the ladle step.

Aspect 21: The product formed from the method of any of aspects 1-17 or 20.
Without further elaboration, it is believed that one skilled in the art can, using the description herein, utilize the present invention. The following examples are included to provide addition guidance to those skilled in the art of practicing the claimed invention. The examples provided are merely representative of the work and contribute to the teaching of the present invention. Accordingly, these examples are not intended to limit the invention in any manner
While aspects of the present invention can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present invention can be described and claimed in any statutory class. Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way appreciably intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.
Throughout this application, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this pertains. The references disclosed are also individually and specifically incorporated by reference herein for the material contained in them that is discussed in the sentence in which the reference is relied upon. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided herein can be different from the actual publication dates, which can require independent confirmation.

E. EXAMPLES

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and/or methods claimed herein can be made and can be evaluated, and are intended to be purely exemplary and are not intended to limit the disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in ° C. or can be at ambient temperature, and pressure can be at or near atmospheric. Unless indicated otherwise, percentages referring to composition are in terms of wt %.
There are numerous variations and combinations of reaction conditions, e.g., component concentrations, desired solvents, solvent mixtures, temperatures, pressures and other reaction ranges and conditions that can be used to optimize the product purity and yield obtained from the described process. Only routine experimentation, if any, will be required to optimize such process conditions. Several methods of this invention are illustrated in the following examples.

Example 1

In this Example, samples of Si-killed ladle slag, Al-killed ladle slag, and calcium aluminate flux were characterized using X-ray fluorescence (XRF) analysis, X-ray diffraction analysis (XRD), and scanning electron microscope (SEM). The results of the XRF chemical analysis for the Si-killed ladle slag, Al-killed ladle slag, and calcium aluminate flux are shown in FIG. 2 and Table 4 below. The results of the XRD phase analysis for the Si-killed ladle slag, Al-killed ladle slag, and calcium aluminate flux are shown in Table 5 below.

TABLE 4

	FeO	SiO2	Al2O3	CaO	MgO	MnO
Sample	(wt %)	(wt %)	(wt %)	(wt %)	(wt %)	(wt %)

Si-killed slag	2.8	28	10	50	7	1.15
Al-killed slag	1.02	3.6	35	51	8	0.4
Calcium	1.8	4.9	38	42	13	0.024
aluminate flux

	TABLE 5

	Phases	Formula

	Al-killed Ladle Slag Phases
	Mayenite	(CaO)₁₂(Al₂O₃)₇
	Calcium Aluminum Oxide	Ca₉(Al₆O₁₈)
	Periclase	MgO
	Calcium Aluminate Flux Phases
	Mayenite	(CaO)₁₂(Al₂O₃)₇
	calcium magnesium aluminum silicate	Ca₂₀Al₂₆Mg₃Si₃O₆₈
	Periclase	MgO
	Si-killed Ladle Slag Phases
	Larnite	Ca₂SiO₄
	Gehlenite	Ca₂Al₂SiO₇
	Tricalcium magnesium ortho silicate	Ca₃Mg(SiO₄)₂

For SEM analysis, the sample to be analyzed was fixed and then examined under scanning microscope. FIGS. 3 and 4 show the SEM micrograph photos for the Si-killed ladle slag. FIG. 4 and Table 6 below show the SEM phase analysis and data for the Si-killed ladle slag.

TABLE 6

Spectrum	In stats.	O	Mg	Al	Si	Ca	Total

P1	Yes	49.58	2.47	4.42	12.92	30.61	100.00
P2	Yes	52.64	0.46	15.39	8.57	22.94	100.00

FIGS. 5 and 6 show the SEM micrograph photos for the Al-killed ladle slag. The SEM phase analysis and data for the Al-killed ladle slag are shown in FIG. 6 and Table 7 below.

TABLE 7

Spectrum	In stats.	O	Mg	Al	Si	S	Ca	Mn	Fe	Total

P1	Yes	50.91	47.78				0.25	0.18	0.88	100.00
P2	Yes	47.65	0.26	16.12	0.64		35.34			100.00
P3	Yes	49.05	0.36	22.27		0.65	27.67			100.00

FIGS. 7 and 8 show the SEM micrograph photos for the calcium aluminate flux. The SEM phase analysis and data for the calcium aluminate flux are shown in FIG. 8 and Table 8 below.

TABLE 8

Spectrum	In stats.	O	Mg	Al	Si	P	Ca	Total

P1	Yes	53.56	0.96	10.84	3.27	31.37	100.00
P2	Yes	49.34	48.56	0.64		1.46	100.00
P3	Yes	51.51	1.79	21.77	1.70	23.23	100.00

Example 2

In the present example, an exemplary method of preparation and collection of Al-killed slag for use in Si-killed steel making is described. The Al-killed slag collection was performed using cast steel slag pots. Prior to collection, 2 to 3 tons of EAF cold slag (30% FeO) was added to the bottom of the slag pot to prevent slag adhesion to the slag pot walls. After casting was completed, the contents of the ladle, which had approximately 2 to 3 tons of liquid slag and any remaining steel, was poured into the slag pot. The slag pot was then transported to the slag yard by slag pot carriers for dumping. At this point, the liquid slag in the slag pot comprised EAF slag (˜30% FeO) at the bottom and Al-killed ladle slag (˜1-2% FeO) at the top. To avoid mixing of EAF slag and Al-killed ladle slag, the top liquid slag can be dumped at one location and the bottom solid portion at an adjacent but separate location. After the slag was cooled for 2 days, it was bagged for use as calcium aluminate flux in Si-killed steel making during tapping as described herein.

Example 3

In this Example, Al-killed slag was evaluated for use in producing Si-killed steel. 750 tons of Si-killed steel were produced (5 heats at 150 ton/each heat) with(experimental) and without(control) Al-killed slag. During the tapping stage of the experimental group, 250 kg of Al-killed slag and 500 kg of lime were added in each heat. For the control group, only 700 kg of lime was used during tapping. A summary of the parameters used during tapping is provided in Table 9 below.

	TABLE 9

	Tapping weight
	(steel)	Tapping Addition

Trial Heat (Experimental)	150 T	500 kg LIME + 250 kg
		Al-killed Slag
Non Trial Heat (Control)	150 T	700 kg LIME

The slag of both steel materials produced in Example 3 were then analyzed. Results of the slag analysis are shown in Table 10 below. The data shows Al-killed ladle slag improved slag fluidity, improved desulfurization, and increased ladle refractory life. The results also show that Al-killed ladle slag is a suitable substitute for lime.

TABLE 10

Slag	FeO	CaO	SiO2	Al2O3	MgO	MnO	S	V Ratio
Sample	%	%	%	%	%	%	%	(B2)	MM

Trial	1.753	48.984	29.192	7.52	8.336	3.2	0.074	1.57	0.23
Control	1.854	50.635	30.165	4.97	7.77	3.88	0.057	1.67	0.34

B2: Basicity: B2 = (CaO) + (MgO)/(SiO2) + (Al2O3); MM: Mannesmann's index: MM = (CaO/SiO2)/(Al2O3).

Claims

1. A method for producing Si-killed steel comprising:

a) supplying Al-killed steel ladle furnace slag; and

b) adding the Al-killed steel ladle furnace slag to a Si-killed steel process to thereby produce Si-killed steel.

2. The method according to claim 1, wherein the Al-killed steel ladle furnace slag comprises silica dioxide in an amount ranging from 1 wt % to 15 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag.

3. The method according to claim 1, wherein the Al-killed steel ladle furnace slag comprises silica dioxide in an amount ranging from 1 wt % to 8 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag.

4. The method according to claim 1, wherein the Al-killed steel ladle furnace slag comprises aluminum oxide in an amount ranging from 15 wt % to 50 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag.

5. The method according to claim 1, wherein the Al-killed steel ladle furnace slag comprises aluminum oxide in an amount ranging from 25 wt % to 45 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag.

6. The method according to claim 1, wherein the method does not comprise adding calcium fluoride.

7. The method according to claim 1, wherein the Al-killed steel ladle furnace slag has an oxygen potential equilibrium ranging from 1 ppm to 20 ppm.

8. The method according to claim 1, wherein the Al-killed steel ladle furnace slag comprises lime in an amount ranging from 40% by weight to 80% by weight based on the total Al-killed steel ladle furnace slag.

9. The method according to claim 1, wherein the Al-killed steel ladle furnace slag is added at a ladle step.

10. The method according to claim 9, wherein the ladle step comprises a tapping step.

11. The method according to claim 10, wherein the ladle step has a residence time in an amount ranging from 25 minutes to 50 minutes after the tapping step.

12. The method according to claim 9, wherein the method comprises a billet caster step after the ladle step.

13. The method according to claim 9, wherein the ladle step comprises desulfurization of the Al-killed steel ladle furnace slag.

14. The method according to claim 1, wherein step (b) comprises adding the Al-killed steel ladle furnace slag to a ladle, wherein the ladle is at a temperature ranging from 1500° C. to 1700° C.

15. The method according to claim 1, wherein the method does not comprise a slab casting step or adding calcium aluminate synthetic slag, or both.

16. (canceled)

17. An article of manufacture comprising Si-killed steel produced using Al-killed steel ladle furnace slag, wherein the article is a long product.

18. The article of manufacture according to claim 17, wherein the long product comprises a bar, a rod, a wire, or a beam.

19. The article of manufacture according to claim 17, wherein the long product does not comprise a flat product.

20. A method for producing Si-killed steel comprising:

a) supplying Al-killed steel ladle furnace slag comprising silica dioxide in an amount ranging from 1 wt % to 8 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag and aluminum oxide in an amount ranging from 15 wt % to 50 wt %, based on the total weight percentage of the Al-killed steel ladle furnace slag;

b) adding the Al-killed steel ladle furnace slag to a Si-killed steel process to thereby produce Si-killed steel;

wherein the Al-killed steel ladle furnace slag is added at a ladle step, wherein the ladle step is at a temperature ranging from 1500° C. to 1700° C.; and

wherein the method comprises a billet caster step after the ladle step.

21. The product formed from the method of claim 1.