TW202526039A - Composition for use in a steel making process - Google Patents

Abstract

The present invention relates to a composition for use in a steel making process [composition (C), herein after], wherein said composition (C) is prepared by mixing (i) at least one steel scale by-product [compound (SSB), herein after] which comprises equal to or more than 35.0 wt. % of free water, relative to the total weight of the compound (SSB) and (ii) at least one first additive in an amount providing a weight ratio of calcium oxide to the free water present in the compound (SSB) equal to or more than 1.50, wherein said first additive comprises calcium oxide in an amount of at least 80.0 wt.%, relative to the total weight of the first additive. The composition (C) after mixing comprises free water in an amount equal to or less than 5.0 wt. %, relative to the total weight of the composition (C).

Description

Components used in steelmaking processes

The present invention relates to a composition for use in a steelmaking process. The present invention further relates to a method for producing the composition, the use of the composition as a raw material in a steelmaking process, and a premix for producing the composition.

During the steelmaking process, waste materials containing hazardous chemicals and metals, known as by-products, such as slag, dust, and sludge, are generated. If not properly disposed of, these wastes can pollute the environment, harm human health, and damage ecosystems. Currently, most of these wastes are disposed of in landfills. However, disposing of large amounts of solid metal waste can affect the environmental balance of soil and groundwater.

Recycling is becoming increasingly important. Recycling is the process of incorporating materials (waste) into new products. This prevents the waste of potentially useful materials by reducing the need for "learned" waste disposal, reduces the consumption of fresh raw materials, reduces energy usage, and reduces air pollution (from incineration) and water pollution (from landfill). Recycling is a key component of reducing modern waste. The European Union is also currently updating its waste management regulations to promote a shift towards a more sustainable model known as the circular economy.

Therefore, it is known to recycle and reuse, for example, BOF and LAF slags into the cement, concrete and road infrastructure markets, thereby significantly reducing the environmental impact of the residual slag and efficiently recovering metals and producing by-products therefrom.

For example, Maschio et al. describe the use of steel scale waste as a component in mortar production (“ Steel scale waste as component in mortars production: An experimental study ” in Construction Materials 4 (2016), pp. 93-101). In this paper, steel scale waste, a by-product of steel production, was used to replace the fine fraction of natural aggregates that were mixed with cement to produce mortar.

The use of steel scale waste as a heterogeneous catalyst for the treatment of liquid waste is also known from Goi et al. (“ Steel Scale Waste as a Heterogeneous Fenton-like Catalyst for the Treatment of Landfill Leachate ,” Ind. Eng. Chem. Res. 2021, 60, 31, 11715–11724) because it is a rich source of iron.

Notably, EP0687309 A1 also discloses a process and apparatus for recovering iron and carbon from blast furnace scrubber sludge (dust, particles, and sludge). After a series of treatments, such as separation by filtration or hydrocyclones, the recovered iron and carbon are recycled to the ironmaking operation.

The steelmaking industry is also impacted by recycling and circular economy issues and is currently undergoing an energy transition. In particular, it must adjust its dependence on raw materials to changing regulations.

However, the specific requirements of the steelmaking industry make the use of recycled products in this sector extremely challenging. For this reason, currently, a significant amount of waste or by-products from the steelmaking process cannot be reused in the steelmaking process. This is also why most of the literature on the recycling and reuse of steelmaking waste pertains to the construction sector (cement, mortar, etc.), where it is easier to use raw materials derived from waste without significantly affecting the quality of the final product.

In view of the above, there is an urgent need for an improved composition for use in steelmaking processes that allows by-products from the steelmaking process to be recycled and reused as raw materials in the steelmaking process.

The inventors have now surprisingly found that it is possible to provide a composition that meets the above-mentioned needs.

Therefore, a composition for use in a steelmaking process [hereinafter referred to as composition (C)] is provided, wherein the composition (C) is prepared by mixing: (i)    at least one steel scale byproduct [hereinafter referred to as compound (SSB)], the steel scale byproduct containing equal to or greater than 35.0 wt.% of free water relative to the total weight of the compound (SSB); (ii)    at least one first additive, the first additive being present in an amount such that the weight ratio of calcium oxide to the free water present in the compound (SSB) is equal to or greater than 1.50, wherein the first additive contains calcium oxide in an amount of at least 80.0 wt.% relative to the total weight of the first additive, and It is characterized in that the composition (C) contains free water in an amount equal to or less than 5.0 wt.% relative to the total weight of the composition (C) after mixing.

In another aspect, the present invention further provides a method for producing a composition for use in a steelmaking process as described in detail above, a premix for producing the composition as described in detail above, and use of the composition as described in detail above as a raw material in a steelmaking process.

As used herein and in the claims, the terms "comprising" and "including" are inclusive or open-ended and do not exclude additional unrecited elements, components, or method steps. Thus, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of."

The term "comprising" used in a patent application should not be construed as limiting the scope to the means listed thereafter; it does not exclude other elements or steps. It should be interpreted as specifying the presence of the recited features, integers, steps, or components mentioned, but does not exclude the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the scope of the expression "a composition comprising A and B" should not be limited to a composition consisting solely of A and B. It means that, for the purposes of the present invention, the only constituent components of the composition are A and B. Therefore, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of."

As used herein, the term "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

Therefore, the composition according to the present invention [hereinafter referred to as composition (C)] is used in a steelmaking process.

In other words, the present invention relates to a composition (C) suitable for use as a raw material in a steelmaking process. In the context of the present invention, the term "steelmaking process" refers to a process for producing steel. Non-limiting examples of such steelmaking processes include the basic oxygen furnace (BOF) process, the electric arc furnace (EAF) process, and the argon oxygen decarburization process (AOD). Preferably, composition (C) is particularly suitable for use as a raw material in the electric arc furnace (EAF) process.

As described above, the composition according to the present invention is prepared from at least one steel scale by-product [hereinafter referred to as compound SSB].

In the context of the present invention, the expression "at least one steel scale by-product [hereinafter referred to as compound SSB]" is intended to refer to one or more than one steel scale by-product. For the purposes of the present invention, mixtures of steel scale by-products may also be used. In the remainder of this document, for the purposes of the present invention, the expression "steel scale by-product" is to be understood in both the plural and singular forms.

In the context of the present invention, compounds (SSB) are intended to refer to by-products of the steelmaking process, also known as waste.

During the high-temperature heat treatment after casting, scale forms on the surface of steel. Typically, at the end of the steelmaking process, the steel is immersed in an acidic bath (also known as a leaching process) to remove the scale present on the steel surface. The acidic solution is then collected. Lime is then added to this acidic solution to raise the pH to approximately 10, causing the dissolved metals to precipitate. The resulting sludge containing the precipitated metals is collected and subjected to a pressing process to separate the solid phase from the liquid phase. The solid phase contains at least metals such as iron (Fe), chromium (Cr), nickel (Ni), and molybdenum (Mo). This solid phase typically also contains a high content of water and is also referred to as scale byproduct, scale waste, or filter cake.

Preferably, the compound (SSB) is a by-product from a stainless steel manufacturing process or a carbon steel manufacturing process or a mixture thereof.

Advantageously, the compound (SSB) can be in various forms, such as a paste, a powder, a crumb, or a mixture thereof. Preferably, the compound (SSB) is a paste. The compound (SSB) can also be in the form of chunks, ground, crushed, or powdered.

As described above, according to the present invention, the at least one steel scale by-product [hereinafter referred to as compound (SSB)] contains free water equal to or greater than 35.0 wt.% relative to the total weight of the compound (SSB).

In the context of the present invention, the term "free water" is intended to refer to the portion of water that evaporates upon heating. In contrast, the term "bound water" generally refers to the water that remains bound to a compound upon heating. It should be understood that those skilled in the art will measure the amount of free water according to standards and common practices known to those skilled in the art. Preferably, unless otherwise mentioned or indicated, free water measurement according to the present invention is performed by subjecting the sample to a heating step at 80°C. According to the present invention, free water is measured in accordance with standard NF 94-050 09-1995 during the 80°C heating step. In other words, free water is measured according to standard NF 94-050 09-1995, except that the heating step is performed at 80°C instead of 50°C or 105°C. Generally, the duration of the heating step is at least 4 hours. It should be further understood that the upper limit of the duration of the heating step depends on various parameters, such as the free water content in the sample and the nature of the sample. Generally, free water measurement is performed until the sample undergoing the measurement reaches a constant weight, as described in standard NF 94-050 09-1995.

Generally, the compound (SSB) contains: or equal to or greater than 40.0 wt.%, or equal to or greater than 45.0 wt.%, or equal to or greater than 50.0 wt.%, or equal to or greater than 55.0 wt.% of free water, relative to the total weight of the compound (SSB).

It is further understood that the upper limit of free water in compound (SSB) is advantageously equal to or less than 80.0 wt.%, or equal to or less than 75.0 wt.%, or equal to or less than 70.0 wt.%, relative to the total weight of compound (SSB).

In one embodiment of the composition of the present invention, free water as described above is present in compound (SSB) in an amount of 35.0 wt.% to 80.0 wt.%, or 35.0 wt.% to 75.0 wt.%, or 40.0 wt.% to 75.0 wt.%, or 45.0 wt.% to 75.0 wt.%, or 50.0 wt.% to 70.0 wt.%, or 55.0 wt.% to 70.0 wt.%, relative to the total weight of compound (SSB).

The compound (SSB) may further comprise fluorine in an amount equal to or greater than 0.2 wt.% expressed as CaF ₂ , relative to the total dry weight of the compound (SSB).

It should be further understood that the expression "fluorine" also refers to the ionic form F-, fluoride.

In the context of the present invention, unless mentioned or indicated otherwise, the expression "dry weight" is intended to mean the weight of the compound (SSB) after evaporation of free water, as detailed above.

Generally speaking, the fluorine (expressed as _CaF₂ ) present in the compound (SSB) can originate from steelmaking processes that produce scale as a by-product. Typically, _CaF₂ is produced during the addition of lime to neutralize acidic solutions. Therefore, the fluorine content in the compound (SSB) depends on the conditions used during the steelmaking process that produces the scale as a by-product.

Generally speaking, the compound (SSB) may contain equal to or greater than 1.0 wt.%, or equal to or greater than 5.0 wt.%, or equal to or greater than 7.0 wt.% of fluorine expressed as CaF ₂ , relative to the total dry weight of the compound (SSB).

It will be further understood that the upper limit of fluorine in compound (SSB), expressed as CaF ₂ , relative to the total dry weight of compound (SSB) may advantageously be equal to or less than 15.0 wt.%, or equal to or less than 12.0 wt.%, or equal to or less than 10.0 wt.%, or equal to or less than 8.0 wt.%.

In one embodiment of the composition of the present invention, fluorine as described above, represented by _CaF2 , is present in compound (SSB) in an amount of 0.2 wt.% to 15.0 wt.%, or 1.0 wt.% to 12.0 wt.%, or 5.0 wt.% to 10.0 wt.%, relative to the total dry weight of compound (SSB).

Preferably, the compound (SSB) may further contain metals such as iron (Fe), chromium (Cr), nickel (Ni), and molybdenum (Mo).

According to the present invention, the compound (SSB) may further comprise iron, expressed as Fe₂O₃, in an amount equal to or greater than 10 wt.%, preferably equal to or greater than 20 wt.%, or equal to or greater than 30 wt.%, relative to the total dry weight of the compound ( _{SSB )} . It should further be understood that the expression "iron" refers to iron present in the compound (SSB) in all its forms (ionic form).

In one embodiment of the composition of the present invention, the upper limit of iron in compound (SSB) expressed _{as Fe2O3} is equal to or less than 60 wt.%, preferably equal to or less than 50 wt.%, or equal to or less than 60 wt.%, relative to the total dry weight of compound (SSB).

Preferably, iron, expressed as Fe ₂ O ₃ , is present in the compound (SSB) in an amount of preferably 10 wt.% to 60 wt.%, preferably 20 wt.% to 50 wt.%, preferably 30 wt.% to 40 wt.%, relative to the total dry weight of the compound (SSB).

According to the present invention, compound (SSB) may further contain chromium in an amount equal to or greater than 0.02 wt.%, preferably equal to or greater than 0.06 wt.%, preferably equal to or greater than 0.10 wt.%, relative to the total dry weight of compound (SSB).

In one embodiment of the composition of the present invention, the upper limit of the chromium content in the compound (SSB) is equal to or less than 15.0 wt.%, preferably equal to or less than 12.0 wt.%, or equal to or less than 10.0 wt.%, relative to the total dry weight of the compound (SSB).

Preferably, chromium is present in compound (SSB) in an amount of 0.02 wt.% to 15.0 wt.%, or 0.06 wt.% to 12.0 wt.%, preferably 0.1 wt.% to 10 wt.%, relative to the total dry weight of compound (SSB).

According to the present invention, the compound (SSB) may further contain nickel in an amount equal to or greater than 0.02 wt.%, preferably equal to or greater than 0.06 wt.%, and preferably equal to or greater than 0.1 wt.%, relative to the total dry weight of the compound (SSB).

In a specific embodiment, the upper limit of nickel in compound (SSB) is equal to or less than 15.0 wt.%, preferably equal to or less than 12.0 wt.%, and preferably equal to or less than 10.0 wt.%, relative to the total dry weight of compound (SSB).

Preferably, nickel is present in compound (SSB) in an amount of 0.02 wt.% to 15.0 wt.%, or 0.06 wt.% to 12.0 wt.%, preferably 0.1 wt.% to 10 wt.%, relative to the total dry weight of compound (SSB).

According to the present invention, compound (SSB) may further contain molybdenum in an amount equal to or greater than 0.02 wt.%, preferably equal to or greater than 0.05 wt.%, preferably equal to or greater than 0.1 wt.%, relative to the total dry weight of compound (SSB).

In one embodiment of the composition of the present invention, the upper limit of the molybdenum content in the compound (SSB) is equal to or less than 15.0 wt.%, preferably equal to or less than 12.0 wt.%, and preferably equal to or less than 10 wt.%, relative to the total dry weight of the compound (SSB).

Preferably, molybdenum is present in compound (SSB) in an amount of 0.02 wt.% to 15.0 wt.%, or 0.06 wt.% to 12.0 wt.%, preferably 0.1 wt.% to 10 wt.%, relative to the total dry weight of compound (SSB).

Preferably, chromium, nickel and molybdenum are present in compound (SSB) in a cumulative amount of 0.1 wt.% to 50 wt.%, preferably 0.2 wt.% to 40 wt.%, and preferably 0.5 wt.% to 30 wt.%, relative to the total dry weight of compound (SSB).

As mentioned above, the composition (C) as described above is prepared by mixing the compound (SSB) as described above with at least one first additive .

In the context of the present invention, the expression "at least one first additive" is intended to refer to one or more than one first additive. For the purposes of the present invention, mixtures of first additives may also be used. In the remainder of this document, for the purposes of the present invention, the expression "first additive" is understood to be both plural and singular.

As described above, the composition (C) described above is prepared by mixing the compound (SSB) described above with at least one first additive in an amount such that the weight ratio of calcium oxide to free water present in the compound (SSB) is equal to or greater than 1.50.

In other words, the first additive is mixed with the compound (SSB) in such a manner that the weight ratio of calcium oxide to free water of the compound (SSB) is equal to or greater than 1.50; .

It is further understood that the lower limit of the amount of the first additive mixed with the compound (SSB) should be sufficient to provide the amount of calcium oxide detailed above.

Advantageously, the first additive is mixed with the compound (SSB) in an amount such that the weight ratio of calcium oxide to free water present in the compound (SSB) is equal to or greater than 1.75, preferably equal to or greater than 1.80, more preferably equal to or greater than 1.90, even more preferably equal to or greater than 2.00.

Advantageously, the first additive is mixed with the compound (SSB) in an amount such that the weight ratio of calcium oxide to free water present in the compound (SSB) is equal to or less than 2.50, preferably equal to or less than 2.25, more preferably equal to or less than 2.15, even more preferably equal to or less than 2.10.

In a preferred embodiment of the method of the present invention, the first additive is advantageously mixed with the compound (SSB) in such an amount that the weight ratio of calcium oxide to free water present in the compound (SSB) is 1.50 to 2.50, more preferably 1.80 to 2.25, and most preferably 2.0 to 2.15.

According to the present invention, the first additive comprises calcium oxide in an amount of at least 80.0 wt.%, relative to the total weight of the first additive. In other words, the term "first additive" is intended to refer to a compound comprising at least 80.0 wt.% of calcium oxide, or a composition comprising at least 80.0 wt.% of calcium oxide, or a mixture thereof.

Advantageously, the first additive comprises calcium oxide in an amount of at least 85.0 wt.%, preferably at least 90.0 wt.%, more preferably at least 95.0 wt.%, even more preferably at least 98.0 wt.%, relative to the total weight of the first additive.

According to a preferred embodiment of the composition of the present invention, the first additive is a compound comprising or consisting essentially of calcium oxide, as described above, wherein the total amount of calcium oxide is equal to or greater than 80.0 wt.%, or greater than 85.0 wt.%, or greater than 90.0 wt.%, or greater than 95.0 wt.%, or ideally greater than 98.0 wt.%, relative to the total weight of the compound.

Generally speaking, those skilled in the art know how to select the first additive to provide the weight ratios detailed above.

According to the present invention, the first additive may further comprise at least one calcium salt other than calcium oxide in an amount equal to or less than 20 wt.%, preferably equal to or less than 15 wt.%, and more preferably equal to or less than 10 wt.%, relative to the total weight of the first additive. In the context of the present invention, the expression "at least one calcium salt" is intended to refer to one or more calcium salts. For the purposes of the present invention, the expression "at least one calcium salt" is to be understood in both the plural and singular forms. Non-limiting examples of such calcium salts include calcium carbonate, calcium hydroxide, calcium sulfate, or calcium nitrate.

According to one embodiment of the present invention, the first additive may further include at least one magnesium salt selected from the group consisting of magnesium carbonate, magnesium oxide, and magnesium hydroxide. In the context of the present invention, the expression "at least one magnesium salt" is intended to refer to one or more magnesium salts. For the purposes of the present invention, the expression "at least one magnesium salt" is understood to include both plural and singular forms.

In this embodiment, the content of magnesium expressed as magnesium oxide in the first additive is equal to or less than 10.0 wt.%, preferably equal to or less than 7.0 wt.%, and more preferably equal to or less than 5.0 wt.%, relative to the total weight of the first additive.

The first additive according to the present invention may further contain impurities in an amount equal to or less than 5.0 wt.%, preferably equal to or less than 4.0 wt.%, and more preferably equal to or less than 2.5 wt.%, relative to the total weight of the first additive. Non-limiting examples of such impurities include silicon, aluminum, iron, sodium, potassium, sulfur, and phosphorus, either alone or in combination. The impurities may also be in the form of salts, oxides, combinations with calcium, or any combination thereof.

The first additive can be a compound, a composition, or a mixture thereof.

The first additive can be synthesized by various methods known in the art or can be of natural origin.

Non-limiting examples of naturally derived first additives include limestone, which may be made from mined (raw) ore. Generally, the limestone contains greater than 95.0 wt.%, greater than 96.0 wt.%, greater than 97.0 wt.%, or ideally greater than 98.0 wt.% of CaCO ₃ relative to the total weight of the limestone.

In a preferred embodiment of the present invention, the first additive is quicklime. Generally speaking, quicklime is made from limestone, in particular by forging limestone.

In this specific example, when the first additive is quicklime, the quicklime has a reactivity ( _t60) of at most 10 minutes. Quicklime reactivity is assessed using the European reactivity on slaking test EN 459-2: Building lime - Part 2: Test method. Generally, quicklime reactivity is expressed as _t60 , which is the time required for 150 g of quicklime to reach a temperature of 60°C when added to 600 cm³ of water. Preferably, the quicklime meets the chemical requirements of calcium lime CL80-R5 according to European standard EN 459-1.

The present inventors have now discovered that when a composition (C) is prepared by mixing the compound (SSB) described above with at least one first additive described above, the amount of the first additive is such that the weight ratio of calcium oxide to free water present in the compound (SSB) is equal to or greater than 1.50, the free water content of the resulting composition (C) is significantly reduced.

According to the present invention, the composition (C) contains free water in an amount equal to or less than 5.0 wt.% relative to the total weight of the composition (C) after mixing the compound (SSB) described above with at least one first additive described above.

The inventors have discovered that composition (C) of the present invention can be safely used in steelmaking processes. A free water content of 5 wt.% or less in composition (C) is a significant figure, as it represents the critical value for safely reintroducing this composition as a raw material in steelmaking processes. In fact, low levels of free water in the raw materials are mandatory in steelmaking processes to prevent the free water from rapidly expanding into a gas. Due to the high temperatures used in steelmaking processes, the free water becomes a gas that occupies a larger volume. This rapid expansion of liquid water into a gas can be so sudden that liquid steel is ejected from the container. This poses a significant safety risk and can potentially damage equipment. Therefore, the use of the first additive according to the present invention is cost-effective because it avoids the need for a further drying step. In addition, it allows the recovery and reuse of by-products, especially the recovery and reuse of high-value metals and alloys contained in the compound (SSB).

The present invention provides a solution for recovering and recycling steel scale by-products and promoting their subsequent reuse in the steelmaking process while improving the efficiency of the process. Given public policies favoring recycling, particularly in the steelmaking sector, the present invention has significant economic potential.

It should be further understood that the definition of free water described above with respect to compound (SSB) is also applicable to composition (C).

Preferably, composition (C) contains equal to or less than 4.5 wt.%, equal to or less than 4.0 wt.%, preferably equal to or less than 3.5 wt.%, more preferably equal to or less than 3.0 wt.%, most preferably equal to or greater than 2.5 wt.%, most preferably equal to or greater than 2.0 wt.%, and even more preferably equal to or less than 1.5 wt.% of free water, relative to the total weight of composition (C).

It should be further understood that, relative to the total weight of composition (C), the lower limit of free water in composition (C) is advantageously equal to or greater than 0.0 wt.%, or equal to or greater than 0.2 wt.%, preferably equal to or greater than 0.3 wt.%, preferably equal to or greater than 0.4 wt.%, more preferably equal to or greater than 0.5 wt.%, even more preferably equal to or greater than 0.7 wt.%, and most preferably equal to or greater than 1.0 wt.%.

In one embodiment of the composition of the present invention, the free water described above is advantageously present in the composition (C) in an amount of 0.0 wt.% to 5.0 wt.%, preferably 0.2 wt.% to 4.5 wt.%, preferably 0.3 wt.% to 4.0 wt.%, more preferably 0.5 wt.% to 3.5 wt.%, more preferably 0.7 wt.% to 3.0 wt.%, 1.0 wt.% to 3.0 wt.% or 1.0 wt.% to 2.0 wt.%, relative to the total weight of the composition (C).

Advantageously, according to the present invention, the composition (C) further comprises fluorine, expressed as CaF 2, in an amount equal to or less than 20.0 wt.%, preferably equal to or less than 15.0 wt.%, preferably equal to or less than 10.0 wt.%, relative to the total dry weight of the composition (C) after mixing the compound (SSB ₎ described above with at least one first additive described above.

It should be further understood that the definition of dry weight described above for compound (SSB) is also applicable to composition (C).

According to one embodiment of the present invention, a second additive may be added to the composition (C) described above, wherein the second additive comprises at least 20.0 wt.% of magnesium in the form of magnesium oxide, relative to the total weight of the second additive.

The amount added to the composition (C) detailed above is determined by the amount of fluorine represented by _CaF2 in the composition (C) and the nature of the second additive.

Advantageously, the second additive is added in such an amount that the weight ratio of magnesium expressed as magnesium oxide to fluorine expressed as _CaF2 in composition (C) is equal to or greater than 5.0.

In the context of the present invention, the expression "at least one second additive" is intended to refer to one or more than one second additive. For the purposes of the present invention, mixtures of second additives may also be used. In the remainder of this document, for the purposes of the present invention, the expression "second additive" is to be understood in both the plural and singular forms.

In the context of the present invention, the expression "second additive" is intended to mean a compound comprising at least one magnesium salt or a composition comprising at least one magnesium salt, or a mixture thereof.

In the context of the present invention, the expression "at least one magnesium salt" is intended to refer to one or more than one magnesium salt.

In the remainder of this document, for the purposes of the present invention, the expression "at least one magnesium salt" is understood in both the plural and singular forms.

Non-limiting examples of suitable magnesium salts can be made from magnesium carbonate, magnesium hydroxide, magnesium oxide, magnesium sulfate, magnesium silicate, or magnesium nitrate.

According to a preferred embodiment of the composition of the present invention, the at least one magnesium salt is selected from the group consisting of magnesium carbonate, magnesium oxide and magnesium hydroxide.

As described above, the composition of the present invention as described above can be prepared by using at least one second additive in an amount such that the weight ratio of magnesium expressed as magnesium oxide to fluorine expressed as _CaF2 in composition (C) is equal to or greater than 5.0.

In other words, the second additive is used in such a manner that the weight ratio of magnesium represented by magnesium oxide to fluorine represented by _CaF2 in composition (C) is equal to or greater than 5.0; .

Generally speaking, one skilled in the art will know how to determine the amount of the second additive required to provide the weight ratios detailed above. The amount of the second additive depends on the magnesium content of the second additive and on the fluorine (expressed as _CaF2 ) in the composition (C) obtained by mixing the compound (SSB) described above with the at least one first additive described above.

In one embodiment of the present invention, the composition (C) is prepared by further adding a second additive in an amount of 400 wt.% to 2500 wt.%, preferably 1000 wt.% to 2000 wt.%, and preferably 1500 wt.% to 1800 wt.%, relative to the weight of fluorine (expressed as _CaF2 ) in the composition after mixing the compound (SSB) described above with at least one first additive described above.

It will be further understood that the lower limit of the amount of the second additive used should be sufficient to provide the magnesium content expressed as magnesium oxide as detailed above.

Advantageously, the second additive is used in an amount such that the weight ratio of magnesium, expressed as magnesium oxide, to fluorine, expressed as _CaF2 , in composition (C) is equal to or greater than 7.0, preferably equal to or greater than 10.0, more preferably equal to or greater than 12.0, most preferably equal to or greater than 15.0, even more preferably equal to or greater than 20.0.

Advantageously, the second additive is used in an amount such that the weight ratio of magnesium, expressed as magnesium oxide, to fluorine, expressed as _CaF2 , in composition (C) is equal to or less than 25.0, preferably equal to or less than 20.0, more preferably equal to or less than 15.0, most preferably equal to or less than 12.0, and even more preferably equal to or less than 10.0.

In a preferred embodiment of the method of the present invention, the second additive is used in an amount such that the weight ratio of magnesium expressed as magnesium oxide to fluorine expressed as _CaF2 in composition (C) is 5.0 to 25.0, preferably 7.0 to 20.0, more preferably 10.0 to 15.0, most preferably 12.0 to 15.0 or 7.0 to 10.0.

According to the present invention, the second additive comprises magnesium in an amount of at least 20.0 wt.% expressed as magnesium oxide relative to the total weight of the second additive. Generally speaking, a person skilled in the art knows how to select a second additive that provides the weight ratios detailed above.

According to a preferred embodiment of the composition of the present invention, the second additive comprises or consists essentially of the magnesium salt described above, wherein the total amount of magnesium, expressed as magnesium oxide, is at least 25.0 wt.%, or at least 30.0 wt.%, or at least 35.0 wt.%, or ideally at least 35.0 wt.%, relative to the total weight of the second additive. Advantageously, the magnesium content, expressed as magnesium oxide, is less than 90.0 wt.%, or less than 80.0 wt.%, or less than 70.0 wt.%, or less than 60.0 wt.%, or less than 55.0 wt.%, or less than 50.0 wt.%, or ideally less than 45.0 wt.%, relative to the total weight of the second additive.

According to a preferred embodiment of the composition of the present invention, the second additive may further comprise at least one calcium salt selected from the group consisting of calcium carbonate, calcium oxide, and calcium hydroxide.

According to a preferred embodiment of the composition of the present invention, the second additive comprises the magnesium salt described above and the calcium salt described above, or consists essentially of the magnesium salt described above and the calcium salt described above, wherein the total amount of magnesium expressed as magnesium oxide and calcium expressed as calcium oxide is greater than 80.0 wt.%, or greater than 85.0 wt.%, or greater than 90.0 wt.%, or greater than 95.0 wt.%, or ideally greater than 98.0 wt.%, relative to the total weight of the compound, and wherein the magnesium content expressed as magnesium oxide is at least 20.0 wt.%, or at least 25.0 wt.%, or ideally at least 30.0 wt.%, relative to the total weight of the second additive. Advantageously, the magnesium content, expressed as magnesium oxide, is less than 90.0 wt.%, or less than 80.0 wt.%, or less than 70.0 wt.%, or less than 60.0 wt.%, or less than 55.0 wt.%, or less than 50.0 wt.%, or ideally less than 45.0 wt.%, relative to the total weight of the second additive. Advantageously, the calcium content, expressed as calcium oxide, is less than 80.0 wt.%, or less than 70.0 wt.%, or less than 60.0 wt.%, or less than 50.0 wt.%, or less than 40.0 wt.%, or less than 30.0 wt.%, or ideally less than 20.0 wt.%, relative to the total weight of the second additive.

Ideally, the magnesium content expressed as magnesium oxide relative to the total weight of the second additive varies between 20.0 wt.% and 80.0 wt.%, or between 20.0 wt.% and 70.0 wt.%, or between 25.0 wt.% and 60.0 wt.%, or between 30.0 wt.% and 50.0 wt.%, or between 30.0 wt.% and 45.0 wt.%.

The second additive may be prepared synthetically by various methods known in the art or may be of natural origin.

Non-limiting examples of naturally derived secondary additives can be made from mined (raw) ores such as dolomite and dolomitic limestone.

Generally speaking, dolomite limestone comprises _MgCO3 and _CaCO3 , wherein _MgCO3 and _CaCO3 are present in a total amount of greater than 95.0 wt.%, or greater than 96.0 wt.%, or greater than 97.0 wt.%, or ideally greater than 98.0 wt.%, relative to the total weight of the dolomite _limestone , and wherein the MgCO3 content may vary from _20.0 wt.% to 45.0 wt.%, or from 25.0 wt.% to 40.0 wt.%, or from 30.0 wt.% to 40.0 wt.%, relative to the total weight of MgCO3 _{and CaCO3} .

Generally speaking, dolomite comprises _MgCO3 and _CaCO3 , wherein _MgCO3 and _CaCO3 are present in a total amount greater than 95.0 wt.%, or greater than 96.0 wt.%, or greater than 97.0 wt.%, or ideally greater than 98.0 wt.%, relative to the total weight of the dolomite limestone, and wherein the _MgCO3 and _CaCO3 contents are present in a molar ratio of 1:1.

Non-limiting examples of suitable second additives for use in the synthetic preparation of the compositions of the present invention may be partially or fully burned dolomite composed of calcium oxide and magnesium oxide (also known as calcined dolomite or dolomitic quicklime or calcined dolomite (dolime)), calcium hydroxide and magnesium oxide (also known as hemihydrated dolomitic lime), or calcium hydroxide and magnesium hydroxide (also known as S-type hydrated lime).

Alternatively, the second additive consists essentially of at least one magnesium salt as described in detail above.

In the context of the present invention, the term "consisting essentially of" is understood to mean that any additional component other than the magnesium salt detailed above is present in an amount of up to 1.0 wt.%, or up to 0.5 wt.%, or up to 0.1 wt.%, based on the total weight of the second additive. Non-limiting examples of such additives are magnesium oxide, magnesia, olivine, and magnesia.

It should be further understood that the first additive and the second additive according to the present invention are two different compounds or compositions.

The inventors have surprisingly discovered that when the second additive described above is used to prepare the composition (C) described above, the negative effect of _CaF₂ on slag viscosity during the steelmaking process is reduced. It has been discovered that _CaF₂ acts as a slag fluidizer. This means that when a composition containing a large amount of _CaF₂ is used as a raw material in a steelmaking process, the viscosity of the slag produced during the process is lower. This slag, with its low viscosity, no longer properly covers the liquid steel, which leads to a decrease in thermal insulation and an increased risk of nitrogen pickup, which in turn can reduce the yield of the process. Therefore, the use of the second additive according to the present invention allows the yield of the steelmaking process to be improved while using a by-product as a raw material.

According to the present invention, the composition (C) further comprises fluorine in an amount equal to or less than 10.0 wt.% expressed as _CaF2 , relative to the total dry weight of the composition (C) obtained by mixing the compound (SSB) described above with at least one first additive described above and at least one second additive described above.

Therefore, the present inventors have found that the composition (C) of the present invention can be safely used as a raw material in a steelmaking process and improves the productivity of the process and reduces the need for other additives during the process.

It should be further understood that the definition of dry weight described above for compound (SSB) is also applicable to composition (C).

Preferably, the composition (C) contains 8.0 wt.% or less, 7.0 wt.% or less, preferably 6.0 wt.% or less, more preferably 5.0 wt.% or less, even more preferably 4.0 wt.% or less, most preferably 3.0 wt.% or less, and most preferably 2.0 wt.% or less of fluorine, expressed as CaF ₂ , relative to the total dry weight of the composition.

It should be further understood that the lower limit of fluorine expressed as _CaF2 in composition (C) is advantageously equal to or greater than 0.0 wt.%, or equal to or greater than 0.2 wt.%, preferably equal to or greater than 0.5 wt.%, preferably equal to or greater than 0.7 wt.%, more preferably equal to or greater than 1.0 wt.%, even more preferably equal to or greater than 1.5 wt.%, and most preferably equal to or greater than 2.0 wt.%, relative to the total dry weight of composition (C).

In one embodiment of the composition of the present invention, the fluorine represented by _CaF2 as described above is advantageously present in the composition (C) in an amount of 0.0 wt.% to 10.0 wt.%, preferably 0.2 wt.% to 8.0 wt.%, preferably 0.5 wt.% to 7.0 wt.%, more preferably 0.7 wt.% to 6.0 wt.%, more preferably 1.0 wt.% to 5.0 wt.%, or 1.5 wt.% to 5.0 wt.% or 2.0 wt.% to 5.0 wt.%, relative to the total dry weight of the composition.

Preferably, the composition (C) further comprises at least one forming agent. Generally, one skilled in the art will know how to select a forming agent that improves the forming step. In practice, the forming agent allows the various components included in the composition (C) described above to be combined to improve the forming step and the mechanical properties of the resulting formed composition (C).

In the context of the present invention, the expression "at least one shaping agent" is intended to mean one shaping agent or more than one shaping agent. Mixtures of shaping agents can be used.

In the remainder of this document, for the purpose of the present invention, the expression "forming agent" is understood to be both plural and singular.

Non-limiting examples of shaping agents are compounds containing at least one sugar and compounds containing at least one stearate. Non-limiting examples of compounds containing at least one sugar are sugar and molasses.

Non-limiting examples of stearates include sodium stearate, calcium stearate, magnesium stearate, zinc stearate, and dihydroxyaluminum stearate. Calcium stearate is particularly preferred.

Preferably, the at least one forming agent comprises at least 30.0 wt.% of at least one saccharide (S) selected from the group consisting of monosaccharides, disaccharides, trisaccharides and tetrasaccharides [hereinafter referred to as sugar (S)], relative to the total weight of the forming agent.

In the context of the present invention, the expression "at least one sugar selected from the group consisting of monosaccharides, disaccharides, trisaccharides and tetrasaccharides [hereinafter referred to as sugar (S)]" is intended to refer to one sugar (S) or more than one sugar (S). A mixture of sugars (S) may be used.

In the remainder of this document, for the purpose of the present invention, the expression "sugar (S)" is understood to be both plural and singular.

In the context of the present invention, the term "sugar" as used herein may have the broadest meaning known in the art.

The sugar (S) may contain one carbohydrate unit or more than one carbohydrate unit, which may be the same or independently different from each other.

Sugars (S) as defined above may also contain one or more carbohydrate units containing five or six carbon atoms, which are called pentoses and hexoses, respectively.

Non-limiting examples of the pentoses mentioned can be made from ribose, arabinose, arabulose, lyxose, lyxulose, ribulose, xylose and xylulose, optionally substituted with at least one halogen, _C1-6 alkyl or _C1-6 alkoxy substituent.

Non-limiting examples of the hexoses mentioned can be made from allose, altrose, fructose, galactose, glucose, gulose, idose, mannose, psicose, sorbose, tagatose, and talose, which are optionally substituted with at least one halogen, C _{1-6 alkyl} , or C 1-6 alkoxy substituent.

According to a preferred embodiment of the present invention, the sugar (S) is selected from the group consisting of monosaccharides and disaccharides.

Preferred monosaccharides are selected from the group consisting of glucose, mannose, fructose, galactose, ribose, arabinose and xylose. More preferably, sugar (S) is selected from the group consisting of glucose, mannose and fructose.

Preferred disaccharides are selected from the group consisting of sucrose, lactose, maltose, trehalose, and cellobiose, and more preferably selected from the group consisting of sucrose, lactose, and maltose. Sucrose is particularly preferred.

According to a more preferred embodiment of the present invention, the sugar (S) product is selected from the group consisting of glucose, mannose, fructose and sucrose. Sucrose is particularly preferred.

Preferably, at least one forming agent comprises at least 40.0 wt.%, more preferably at least 50.0 wt.%, even more preferably at least 60.0 wt.%, most preferably 70.0 wt.%, and more preferably at least 75 wt.% of at least one saccharide (S) described above, relative to the total weight of the forming agent.

Generally speaking, those skilled in the art know how to determine the amount of forming agent for the modified forming step, as described in detail above. Preferably, composition (C) of the present invention comprises at least 1.0 wt.%, or at least 1.5 wt.%, or at least 2.0 wt.%, or at least 2.5 wt.% of the forming agent, as described in detail above, relative to the total weight of composition (C).

It should be further understood that, relative to the total weight of the composition (C), the upper limit of the forming agent in the composition (C) is advantageously equal to or less than 8.0 wt.% or equal to or greater than 7.0 wt.%, preferably equal to or greater than 6.5 wt.%, preferably equal to or greater than 6.0 wt.%, more preferably equal to or greater than 5.5 wt.%, and even more preferably equal to or greater than 5.0 wt.%.

In one embodiment of the composition of the present invention, the forming agent described above is advantageously present in the composition in an amount of 1.0 wt.% to 8.0 wt.%, preferably 1.5 wt.% to 7.0 wt.%, preferably 2.0 wt.% to 6.5 wt.%, more preferably 2.0 wt.% to 6.0 wt.%, more preferably 2.5 wt.% to 6.0 wt.%, or 2.5 wt.% to 5.5 wt.%, or 2.0 wt.% to 5.0 wt.%, relative to the total weight of composition (C).

Preferably, composition (C) is in the form of a solid composition. For the purposes of the present invention, the term "solid composition" is intended to refer to a composition in the form of a powder, fiber, dust, tablet, pellet, aggregate, extrudate or agglomerate, or in the form of particles such as granules or crumbs.

Preferably, the composition (C) is in a form selected from the group consisting of: powder, aggregate, agglomerate, or a mixture of two or more thereof. Preferably, the composition (C) is in a form selected from the group consisting of: aggregate, agglomerate, or a mixture of two or more thereof. Method for producing composition ( C )

A method for producing composition (C) is also an aspect of the present invention.

It should be further understood that all definitions and preferences described above also apply to all other specific examples described below.

The composition (C) of the present invention can be prepared by various methods known in the art.

In one embodiment of the present invention, the method for preparing the composition (C) described above comprises mixing ( a ) at least one compound (SSB) described above, ( b ) at least one first additive described above, and ( c ) optionally at least one second additive described above.

The inventors have further discovered that the composition (C) prepared according to the present invention is particularly suitable for use as a raw material in steelmaking processes.

It will be understood that one skilled in the art will perform such mixing according to normal practice, such as specifically using optimal times, speeds, weights, volumes, and batches.

Furthermore, it should be understood that any order of mixing the various components contained in composition (C) described in detail above is acceptable.

Where appropriate, the first additive described above and the second additive described above may be premixed to form a premix before being mixed with the compound (SSB), or the first additive and the second additive may be mixed separately with the compound (SSB).

When the first additive and the second additive are mixed separately with the compound (SSB), the first additive and the second additive may be mixed at the same time, or the second additive may be mixed after the first additive, if necessary.

It should be further understood that the various components contained in the composition (C) described above can be introduced in solid form or in liquid form. Non-limiting examples of solid forms are powders or dusts, however, they can also be in compressed form (e.g., tablets, pellets or granules) to produce composition (C).

The forms of the various compounds contained in the composition (C) described above are generally known to those skilled in the art.

The various components contained in composition (C) are usually in the solid form as described above, however, they may also be present in solution.

For example, when molasses is used as a bulking agent, the compound is a liquid, that is, a viscous liquid.

Generally speaking, the mixing described above can be performed using various mixing means known in the art. Non-limiting examples of such mixing means include mechanical mixing, such as conventional mixers and blenders, high-intensity mixers, and electric stirrers. Such mixers, blenders, and stirrers may be equipped with at least one dispersing disk. High shear forces may be applied during mixing to improve the homogeneity of composition (C).

Preferably, the mixing is carried out until a homogeneous mixture is obtained.

Advantageously, composition (C) can be further converted into pellets, tablets, agglomerates, extrudates, aggregates or granules, or mixtures thereof. Such conversion methods are known in the art.

In a preferred embodiment, the mixed composition (C) is then subjected to a forming step. Generally, during this forming step, the composition (C) is given a shape. Various forming processes are known in the art, and non-limiting examples of such forming processes include granulation, compaction, slurry casting, aggregation, and extrusion. Preferably, the forming process is a compaction process. Non-limiting examples of compaction processes include cold isostatic pressing, tableting, briquetting, and roll pressing. Following the forming process, the formed composition (C) can take various forms, such as pressed bodies, tablets, briquettes, pellets, and extrudates.

Preferably, according to the present invention, the shaped composition (C) is in the form of agglomerates or aggregates.

Preferably, according to the present invention, there is a waiting step between the mixing and forming steps.

Advantageously, the waiting step lasts for at least 6 hours, preferably at least 12 hours, more preferably at least 18 hours, even more preferably at least 20 hours, and most preferably at least 24 hours.

In a preferred embodiment of the present invention, the shaping agent is added to composition (C) after the mixing described above and before the shaping step described above.

When the process includes a waiting step, the forming agent can be added before and/or during and/or after the waiting step. It is particularly preferred to add the forming agent after the waiting step and before the forming step.

A premix of the first additive described above and the second additive described above is another aspect of the present invention.

It should be further understood that all definitions and preferences described above apply equally to premixes.

The use of the composition (C) described above as a raw material in a steelmaking process is another aspect of the present invention.

It should be further understood that all definitions and preferences described above also apply to the use of composition (C) as a raw material in a steelmaking process.

The present invention will now be described in more detail with reference to the following examples, which are for illustrative purposes only and are not intended to limit the scope of the present invention. Test Methods Measurement of Free Water

The free water measurement is performed by subjecting the sample to a heating step at 80°C until the sample reaches a constant weight.

The fluorine content is measured after the free water measurement described above. Therefore, the fluorine content is measured on a "dry sample" after the free water has evaporated as detailed above.

Fluorine was measured using a wavelength dispersive X-ray fluorescence spectrometer from Malvern Panalytical Zetium.

The reactivity of quicklime is evaluated using the European test for the reactivity of lime, EN 459-2: Building lime - Part 2: Test methods. The reactivity _t60 is determined as the time required for 150 g of quicklime to reach a temperature of 60°C when added to 600 cm³ of water. Loss on ignition ( LOI ) measurement

To determine the amount of bound water and carbonate in the present invention, thermogravimetric analysis (TGA) was used to obtain the LOI. This was performed by gradually increasing the temperature of a sample of the composition from room temperature to at least 950°C (or to a constant mass) at a rate of 5°C/minute in a kettle under a nitrogen flow, while simultaneously measuring its weight on an analytical balance. The sample weight was plotted against temperature to observe the thermal transition/decomposition that occurs with increasing temperature. One or more hydrated compounds included in the present invention decompose between 350°C and 550°C by releasing water (hereinafter referred to as "bound water"). Therefore, the mass loss that occurs between 350°C and 550°C corresponds to the amount of "bound water" (expressed as _H₂O ) according to the present invention. One or more carbonate compounds contained in the composition of the present invention decomposes between 550°C and 950°C (or constant mass) by releasing CO _2. Therefore, the mass loss occurring between 550°C and 950°C (or constant mass) corresponds to the amount of total carbonate (expressed as CO ₂ ) according to the present invention. Measurement of the mechanical resistance of agglomerated compositions

Compressive strength is measured by applying a progressively increasing load (or force) to a solid sample until fracture. The maximum force applied before fracture is recorded and used as an indicator of mechanical resistance.

The measurements were performed using a laboratory press, Mecmesin OmniTest. Example 1 ( E1 )

Example 1 was implemented using raw materials having the compositions and properties described in Tables 1 to 3. Table 1 : Steel Scale Byproduct Compounds ( Compound SSB ) Wt.% Free water * 55.0 CaF ₂ ** 36.2 Fe ₂ O ₃ ** 30.4 Cr ** 5.3 Ni ** 4.1 Mo ** 0.1 * Relative to the total weight of compound SSB**Relative to the total dry weight of compound SSB Table 2 : First additive - composition Amount (wt.%*) Na ₂ O 0.04 MgO 1.55 Al ₂ O ₃ 0.252 SiO ₂ 0.745 P ₂ O ₅ 0.025 SO ₃ 0.123 _K2O 0.046 CaO 92.94 Ti 0.032 Fe ₂ O ₃ 0.090 Zn 0.005 Sr 0.041 H ₂ O (bound water) 0.9 CO ₂ (carbonate) 0.7 * Relative to the total weight of the first additive Table 3 : First Additive - Reactivity Reactivity T60 (minutes) 1.6 T°2' (℃) 63.2 Tmax (℃) 74.7

Compound SSB, described in Table 1, was mixed with the first additive, detailed in Tables 2 and 3, in an amount such that the weight ratio of calcium oxide to free water present in the compound (SSB) was 1.62. Mixing was performed using an Eirich intensive mixer, Model R01, at a stirrer speed of 300 rpm and a rotor speed of 42 rpm. As detailed in Tables 1 and 2, 1.5 kg of compound SSB was added to the mixer along with 500 g of the first additive and mixed for 30 minutes. Next, an additional 500 g of the first additive was added and mixed for 30 minutes. Next, an additional 500 g of the first additive was added and mixed for 30 minutes.

The obtained composition was sampled 2 hours after the start to measure its free water content. The free water content was 4.7 wt% relative to the total weight of the composition. This result shows that the addition of the first additive allows the production of a composition having a free water content of less than 5 wt%. Therefore, the composition can be used as a raw material in a steelmaking process. Example 2 ( E2 )

Example 2 is achieved by mixing the composition obtained in Example 1 with a second additive as detailed in Table 4. Table 4 : Second additive - composition Amount (wt.%*) Free H ₂ O < 0.01 MgO 27.5 CaO 40.0 Fe ₂ O ₃ 1.8 F < 0.01 SO ₃ 1.8 SiO ₂ 3.0 Total LOI (bound water + carbonates) 26.0 *Relative to the total weight of the second additive

As described above, the fluorine content expressed as _CaF2 in the composition obtained in Example 1 was measured and found to be 8.8 wt.% relative to the total dry weight of the composition. Next, 216.6 g of the second additive described in Table 4 was added and mixed with 200 g of a sample taken from the composition obtained in Example 1.

Mixing was carried out for 10 minutes using a WABTurbula® mixer at 72 rpm. The resulting composition had a free water content of 2.2 wt.%, relative to the total weight of the composition. In this composition, the weight ratio of magnesium, expressed as magnesium oxide, to fluorine, expressed as CaF ₂ , was 5.0. This result demonstrates that the addition of the second additive allows the production of a composition that can be safely used as a raw material in steelmaking processes. Comparative Example 3 ( CE3 )

The SSB compound described in Table 1 was mixed with the first additive detailed in Tables 2 and 3 in an amount such that the weight ratio of calcium oxide to free water present in the compound (SSB) was 1.1. Mixing was performed using a high-shear mixer as described in standard NF P 94-093. 1.5 kg of the SSB compound was added to the mixer along with 500 g of the first additive, as detailed in Tables 1 and 2, and mixed for 30 minutes. Subsequently, an additional 500 g of the first additive was added and mixed for another 30 minutes.

The composition obtained was sampled 1 hour after the start to measure its free water content, which was 17.4 wt% relative to the total weight of the composition. This result shows that the addition of the first additive at a lower ratio does not allow to obtain a composition that can be safely used as a raw material in the steelmaking process. Table 5 : Results E1 E2 CE3 Free water in composition ( C ) 4.7 2.2 17.4 CaO/ free H ₂ O ratio during addition of the first additive 1.62 1.62 1.08 MgO/ _CaF2 ratio after adding the second additive N/A 5.0 N/A Example 4 of the Forming Process

Example 4 was implemented using the composition obtained in Example 1.

15 g of the product was pressed using a laboratory-scale tableting apparatus at 94 MPa to obtain an agglomerated composition in the form of tablets having a compressive mechanical strength of 890 N. This result shows that the composition of the present invention can be shaped and the resulting shaped product exhibits good mechanical strength.

without

without

Claims (16)

A method for producing a composition for use as a raw material in a steelmaking process [hereinafter referred to as composition (C)], the method comprising mixing the following: ( a ) at least one steel scale by-product [hereinafter referred to as compound (SSB)], the steel scale by-product containing equal to or greater than 35.0 wt.% of free water relative to the total weight of the compound (SSB); ( b ) at least one first additive, the at least one first additive being present in an amount such that the weight ratio of calcium oxide to the free water present in the compound (SSB) is equal to or greater than 1.50, wherein the first additive contains calcium oxide in an amount of at least 80.0 wt.% relative to the total weight of the first additive; wherein the composition (C) contains equal to or less than 5.0 wt.% of calcium oxide relative to the total weight of the composition (C). wt.% of free water. The method of claim 1, further comprising mixing: ( c ) at least one second additive in an amount such that the weight ratio of magnesium expressed as magnesium oxide to fluorine expressed as _CaF2 in the composition (C) is equal to or greater than 5.0, wherein the second additive comprises at least 20.0 wt.% of magnesium expressed as magnesium oxide relative to the total weight of the second additive; wherein the composition (C) further comprises fluorine expressed as _CaF2 in an amount equal to or less than 10.0 wt.% relative to the total dry weight of the composition (C). The method of claim 1 or claim 2, wherein the compound (SSB) further comprises iron in an amount of 20 wt.% to 50 wt.% expressed _{as Fe2O3} relative to the total dry weight of the compound (SSB). The method of any one of claims 1 to 3, wherein the compound (SSB) further comprises chromium, nickel, and molybdenum in a cumulative amount of 0.5 wt.% to 30 wt.% relative to the total dry weight of the compound (SSB). The method of any one of claims 1 to 4, wherein the first additive is quicklime, preferably the quicklime has a reactivity t60 of at most 10 minutes, wherein the reactivity is measured according to the European digestion reactivity test EN 459-2. The method of any one of claims 2 to 5, wherein the at least one magnesium salt is selected from the group consisting of magnesium carbonate, magnesium oxide, and magnesium hydroxide. The method of any one of claims 1 to 6, wherein the second additive is selected from the group consisting of calcined dolomite, dolomite, magnesium oxide, magnesia, olivine, magnesia, and mixtures of two or more thereof. The method of any one of claims 1 to 7, wherein the composition (C) is in a form selected from the group consisting of powder, aggregate, agglomerate or a mixture of two or more thereof. The method of any one of claims 1 to 8, wherein the at least one first additive and the at least one second additive are premixed to form a premix prior to mixing the at least one compound (SSB). The method of any one of claims 1 to 9, wherein the component (C) undergoes a forming process after the mixing, preferably, the forming process is a compacting process. The method of claim 10, wherein the composition (C) is in a shaped form selected from the group consisting of tablets, pellets, aggregates, pressed bodies, agglomerates, granules or a mixture of two or more thereof after the forming process. The method of claim 10 or claim 11, wherein the method further comprises a waiting step between the mixing and the forming process. The method of claim 12, wherein the waiting step lasts for at least 18 hours, preferably at least 24 hours. A composition for use as a raw material in a steelmaking process obtained by the method of any one of claims 1 to 11 [hereinafter referred to as composition (C)], wherein the composition (C) contains free water in an amount equal to or less than 5.0 wt.% relative to the total weight of the composition (C) after mixing. A premix for producing the composition (C) of any one of claims 9 to 13, wherein the premix comprises the at least one first additive and the at least one second additive. A use of a composition (C) obtained by the method of any one of claims 1 to 13 as a raw material in a steelmaking process, preferably, the steelmaking process is selected from the group consisting of a basic oxygen furnace (BOF) process, an electric arc furnace (EAF) process and an oxydecarburization process (AOD).