Patent Application
20250122587
The present disclosure relates to a method for producing steel, and in particular a method of producing steel using purified iron ore and hydrogen.
Steel is numerous aspects of everyday life, from bridges and skyscrapers to cars and consumer goods. Currently, most steel production companies utilize two primary process flows to turn iron ore into steel, and they generally require at least three essential steps. For example, in a first process flow, iron ore is first pelletized or sintered, and then, second, converted into pig iron in a blast furnace. Third, the pig iron is converted into steel via a basic oxygen furnace (BOF) or an electric arc furnace (EAF). In a second process flow, iron ore is first pelletized or sintered, and then, second, reduced via a direct reduced iron (DRI) furnace into sponge iron. Third, the sponge iron is converted into steel via an EAF.
Both steel production workflows are time and energy-intensive as they need to remove impurities, such as silicon (Si), aluminum (Al), sulfur(S), phosphorus (P), from the raw materials to reach the purity that is needed to make steel. Both the blast furnace approach (flow 1) and the DRI Furnace approach (flow 2) also have complex flowsheets. As such, the heating and the burning processes of these steel production workflows result in detrimental waste and air pollution, including CO2 emissions. According to Carbon Brief, the steelmaking industry is responsible for 7%-9% of global CO2 emissions.
While some progress has been made in the steel industry to reduce CO2 emissions, the current processes are still time and energy-intensive, result in waste, and further produce steel that still includes noticeable amounts of impurities.
In regard to the above background information, the present disclosure is directed to providing methods for producing steel using super-pure iron ore powder and hydrogen.
In a first aspect, a method for producing steel using super-pure iron ore powder and hydrogen is provided. In the method, iron ore concentrate is purified to form super-pure iron ore powder, wherein the super-pure iron ore powder has a purity of at least 98%. The super-pure iron ore powder is then reduced with hydrogen introduced into a first furnace, wherein the first furnace is a hydrogen electric furnace, a hydrogen electromagnetic induction furnace, or hydrogen thermal plasma furnace. The reduced iron product is melted in a second furnace, wherein the second furnace is a hydrogen electric furnace, a hydrogen electromagnetic induction furnace, hydrogen thermal plasma furnace, or an electrical arc furnace. A steel product of the reducing and melting steps is then cooled. The process results in zero carbon dioxide emissions.
In another aspect, the step of purifying comprises: grinding the iron ore concentrate in a ball mill or vertical mill to dissociate iron ore particles from gangue minerals in the iron ore concentrate to form iron ore slurry; separating the iron ore particles from the gangue minerals via a mineral processing equipment to form purified iron ore particles, wherein the mineral processing equipment comprises a magnetic separator, gravity separation equipment, or flotation equipment; and dewatering, filtering, and drying the purified iron ore particles to form the super-pure iron ore powder. In a further aspect, the super-pure iron ore powder has a particle size of less than 100 mesh. In another aspect, the super-pure iron ore powder has a particle size of less than 300 mesh.
In a further aspect, the super-pure iron ore powder is reduced into a solid iron form via the first furnace at a temperature in the range of approximately 500-1200° C., and the reduced iron product is melted in the second furnace at a temperature of approximately 1400-1600° C.
In another aspect, the first furnace and the second furnace are the same furnace and the first furnace and the second furnace are a hydrogen electric furnace or a hydrogen electromagnetic induction furnace, wherein the super-pure iron ore powder is first reduced with hydrogen in the furnace and then melted to form the steel product.
In another aspect, the first furnace and the second furnace are the same furnace and the first furnace and the second furnace are a high-temperature hydrogen electric furnace or a hydrogen electromagnetic induction furnace, and wherein the super-pure iron ore powder is first melted in the furnace and then reduced with hydrogen to form the steel product.
In another aspect, the first furnace and the second furnace are the same furnace and said furnace is a hydrogen thermal plasma furnace, and the super-pure iron ore powder is reduced and melted simultaneously in the hydrogen thermal plasma furnace.
In another aspect, the super-pure iron ore powder can be reduced into liquid form or solid form, wherein when the super-pure iron ore powder is reduced in solid form, the temperature of the first furnace is in the range of approximately 500-1200° C., and wherein when the super-pure iron ore powder is reduced in liquid form, the temperature of the first furnace is in the range of approximately 1400-1600° C.
In another aspect, the first furnace is a hydrogen thermal plasma furnace, and the temperature of the hydrogen thermal plasma furnace does not exceed 5000° C.
In another aspect, the hydrogen introduced into the first furnace has a purity of approximately 5-100%.
In another aspect, the iron ore concentrate comprises hematite type iron ore or magnetite type iron ore or both.
In another aspect, the first furnace and the second furnace are the same furnace.
In another aspect, the iron ore powder has a purity of at least 99.0%.
In another aspect, the first furnace is a hydrogen electric furnace and the super-pure iron ore powder is reduced at a temperature of approximately 900° C. for approximately 120-180 minutes, and the second furnace is a hydrogen electric furnace, and the reduced iron product is melted at a temperature of approximately 1550° C. for approximately 30 minutes.
In a second aspect, a method for producing steel using super-pure iron ore powder and hydrogen is provided. In the method super-pure iron ore powder is supplied, wherein the super-pure iron ore powder has a purity of at least 98% and is substantially free of gangue minerals. The super-pure iron ore powder is then reduced with hydrogen in a hydrogen electric furnace to form a solid iron, wherein the hydrogen reduction reaction in the furnace occurs at a temperature range of approximately 500-1200° C. The solid iron is then melted in the hydrogen electric furnace to form a melted steel product, wherein the solid iron is melted at a temperature in a range of approximately 1400-1600° C. The steel product of the reducing and melting steps is then cooled, wherein the process results in zero carbon dioxide emissions.
In another aspect, the super-pure iron ore powder is reduced at a temperature of approximately 900° C., and the solid iron is melted at a temperature of approximately 1550° C. In a further aspect, the super-pure iron ore powder is reduced at a temperature of approximately 900° C. for approximately 120-180 minutes, and the solid iron is melted at a temperature of approximately 1550° C. for approximately 30 minutes.
In another aspect, the method does not require coal, coke, or bentonite.
In a third aspect, a method for producing steel using super-pure iron ore powder and hydrogen is provided. In the method, the super-pure iron ore powder is reduced and melted in a hydrogen electric furnace to form a steel product, wherein the super-pure iron ore powder is reduced with hydrogen and wherein the hydrogen reduction reaction and melting of the super-pure iron ore powder in the furnace occurs simultaneously at a temperature in a range of approximately 1400-1600° C. for approximately 30-60 minutes.
Any combinations of the various embodiments and implementations disclosed herein can be used. These and other aspects and features can be appreciated from the following description of certain embodiments and the accompanying drawings and claims.
The processes of the present disclosure will be described in more detail below and with reference to the attached drawings.
Disclosed herein are methods for producing steel using super-pure iron ore powder (SPIOP) and hydrogen. The present methods result in zero CO2 emissions, and in one or more embodiments provides a one-step steelmaking process flow. In one or more embodiments, the SPIOP in the present method is first produced from iron ore concentrate or a feed of pellets or sinters. In this step, the iron ore concentrate (typically about 85%-95% purity of iron oxide content) is purified to about 98-100% purity of iron oxide content, whereby the contents of harmful impurities (like Si, AI, P, S) are mechanically removed.
The SPIOP is then reduced with hydrogen and melted in one or more high-temperature furnaces (e.g., hydrogen electric furnace). The hydrogen reduction of the SPIOP and the melting of the reduced product can occur in the same furnace or an option of a different furnace. The resulting steel product is then cooled or sent to the next steel refining facility in molten form. The final steel product is a mild steel with very few impurities (e.g., Si, AI, P, S).
These and other aspects of the present methods are described in further detail below. Further, as used in the present application, the terms “about” and “approximately” when used in conjunction with a numerical value refer to any number within about 5, 3 or 1% of the referenced numerical value, including the referenced numerical value.
As mentioned above, in accordance with one or more embodiments, the present application discloses methods for producing steel using super-pure iron ore powder (SPIOP) and hydrogen.
In one or more embodiments, the resulting SPIOP has a purity of at least 98%. In at least one embodiment, the resulting SPIOP has a purity of at least 99%. In one or more embodiments, the resulting SPIOP has a particle size of less than approximately 100 mesh. In at least one embodiment, the SPIOP has a particle size of less than 325 mesh.
In one or more embodiments, the SPIOP is purified (step S105) via a series of specific steps, as exemplified in the flow diagram of
With continued reference to
In one or more optional steps, a sample of the resulting SPIOP can be tested (e.g., via analytical chemistry methods) to ensure that the super-pure iron ore powder product meets the preferred purity requirements and is substantially free of gangue minerals (e.g., at least 98% purity or at least 99% purity). If the physical separation equipment (e.g., magnetic separator) fails to deliver the required purity of iron ore, either the iron ore concentrate goes through the purification process again to reach the level of qualified purity needed, or the disqualified iron ore concentrate will be turned into DRI and disqualified clean steel. The disqualified DRI/clean steel will be discharged and recycled as inputs to an electric arc furnace (EAF) to produce steel the conventional way.
While the remaining disclosure discusses method for steelmaking with the SPIOP in a hydrogen (H2)-based process, it is noted that the produced SPIOP can alternatively be used in non-hydrogen steelmaking processes (e.g., electrowinning of iron ore, molten iron oxide electrolysis), where the SPIOP acts as the feedstock.
Referring back again to
At steps S115, the SPIOP is introduced with hydrogen (H2) into a first furnace, and the SPIOP undergoes a reduction reaction with H2. In one or more embodiments, the first furnace can be a hydrogen reduction furnace, or more specifically a hydrogen electric furnace (e.g., belt-type, tube-type, box-type), a hydrogen electromagnetic induction furnace, or a hydrogen thermal plasma furnace. In at least one embodiment, the SPIOP is placed in a corundum crucible or similar container before being introduced into the first furnace. The H2 can be introduced into the first furnace as a gas via a gas line in fluid connection with the first furnace, for example. The H2 introduced into the first furnace can have a purity of approximately 5-100%. In one or more embodiments, the chemical reaction(s) in the reduction step are as follows:
3Fe2O3+H2→2Fe3O4+H2O
Fe3O4+H2→3FeO+H2O
FeO+H2→Fe+H2O
The SPIOP can be reduced in the form of a liquid or a solid. In one or more embodiments, to reduce the SPIOP in solid form, the first furnace is operated in a temperature range of approximately 500-1200° C. In one or more embodiments, to reduce the SPIOP in liquid form, the first furnace is operated in a temperature range of approximately 1400-1600° C. In at least one embodiment, the first furnace is a hydrogen reduction furnace, that can be made of alumina fiber material and heated by high-quality molybdenum wire, for example. The hydrogen reduction furnace can have a maximum operating temperature of approximately 1700° C. in accordance with at least one embodiment.
In at least one embodiment in which the SPIOP is reduced in solid form, the solid form can be a sponge iron form. For example, in one or more implementation, the first furnace can be a hydrogen reduction furnace and the SPIOP can be reduced into a solid sponge iron form in the hydrogen reduction furnace operating in a temperature range of approximately 500-1200° C.
In general, when the SPIOP is placed in the first furnace for reduction, the furnace is heated to the desired temperature or temperature range, and kept constant for the duration of the reduction step. For example, in one or more embodiments, the SPIOP can be reduced in the first furnace at an operating temperature of approximately 900° C. for approximately 180 minutes. Before heating up the furnace to the operating temperature, the operator can optionally perform a gas leak by charging nitrogen and/or argon into the furnace via an injection tube as is known and understood in the art. After the gas leak testing, H2 can replace the nitrogen/argon in the injection tube to provide the H2 into the furnace for the reduction reaction. Once the reduction reaction is complete, excess H2 that exits the furnace via exhaust can be recycled or reused for subsequent use. For example, H2 can be recycled or reused after removing the water in the exhaust using existing equipment in the art, including equipment made by companies such as MIDREX, ENERGIRON, FINEX.
In general, the present methods do not require the use of a slag component (e.g., CaO) or alloy materials (e.g. C, Mn, Ni, Cr). However, in an alternative embodiment, a slag component can optionally be added to the first furnace or second furnace to go further in removing any remaining impurities from the product (e.g. Si) to produce high-pure iron (e.g., 99.9%), or alloy materials can be optionally added to the first furnace or the second furnace to assist in producing carbon-steel or other alloy steel.
Once the reduction reaction of the SPIOP in the first furnace is complete, at step S120 the reduced iron product is melted in a second furnace to form a steel product. The second furnace can be, for example, a hydrogen electric furnace (e.g., tube furnace), a hydrogen electromagnetic induction furnace, a hydrogen thermal plasma furnace, or an electrical arc furnace. In certain embodiments, the first and second furnaces in the method can be a single furnace. In certain embodiments, the first and second furnaces can be separate furnaces and either the same type of furnace or different types of furnaces.
The reduced SPIOP is melted at a higher temperature as compared with the operating temperature during the reduction reaction. Specifically, in one or more embodiments, the second furnace can have an operating temperature range of approximately 1400-1600° C. In at least one embodiment, the operating temperature of the second furnace is 1550° C. In one or more embodiments, the reduced iron product is melted in the second furnace for approximately 30-45 minutes. In at least one embodiment, the reduced iron product is melted in the second furnace for approximately 30 minutes. In certain embodiments, the reduction step (S115) and melting step (S120) can be performed in a single furnace, such as a high-temperature hydrogen tube furnace.
In certain embodiments, the melting step of S120 can occur prior to the reducing step S115. For example, in at least one embodiment, the first furnace and the second furnace are the same, single furnace (e.g., high-temperature hydrogen tube furnace) and the SPIOP can be melted first and then reduced with hydrogen second to form the steel product. In this embodiment, the operating temperature range for the furnace is approximately 1400-1600° C.
In certain embodiments, the reducing step S115 and the melting step S120 can occur simultaneously. For instance, in at least embodiment, the first furnace and the second furnace are the same, single furnace (e.g., a hydrogen electric furnace such as a high-temperature hydrogen tube furnace; hydrogen electromagnetic induction furnace; hydrogen thermal plasma furnace) and the SPIOP is reduced with hydrogen and melted simultaneously at an operating temperature of approximately 1400-1600° C. for approximately 30-60 minutes. Thus, in at least this embodiment, the present method can provide a one-step process for making steel from SPIOP.
Once the SPIOP has been melted, at step S125 the steel product is cooled. For instance, in at least one embodiment, once the reduced iron product is melted, the power of the furnace is turned off to reduce the temperature in the furnace to room temperature to allow the steel product (sometimes referred to as mild steel) to cool. Additionally, any flow of nitrogen or argon in the second furnace is stopped. Nitrogen and argon can have multiple uses in one or both of the furnaces, including use as protective gases. For example, nitrogen and argon can be used to push the air out of the tube before injecting hydrogen to reduce risk of combustion. Nitrogen or argon can also be used to prevent the reduced iron from re-oxidation during cooling. Alternatively, instead of cooling, the steel product can be sent to another steel refining facility in molten form.
Once the steel product has cooled, a sample of the steel product can optionally undergo a chemical analysis to test the attributes of the product (e.g., test for impurities).
At step S130, the process ends. The overall process of the present application is a “green” process that results in zero carbon dioxide emissions. Specifically, in one or more embodiments, the process does not use coal, coke, lime, dolomite, bentonite, or organic binder. Only SPIOP, hydrogen and electricity are used. By not including coke and coal in the process, CO2 emissions are avoided, and avoiding the use lime, dolomite or organic binder can reduce the cost, amount of solid waste.
The present methods provide several advantages over conventional methods, and addresses some shortcomings of conventional systems and methods. For example, the present method is environmentally friendly and drastically reduces the amount of solid waste associated with a steelmaking process. Specifically, the present method does not use certain non-renewable resources, such as coal, limestone, dolomite, or bentonite, and the present methods do not produce carbon dioxide (CO2) or slag. This is in direct contrast with conventional processes of the steelmaking industry, which are responsible for 7%-9% of global CO2 emissions. Additionally, the present methods greatly reduce operational costs, capital costs, and energy consumption as compared with prior steelmaking processes. Further, the present methods use of hydrogen from the steel production makes the present processes even better for the environment relative to prior processes, as hydrogen is a renewable energy source.
Another advantage of the present methods is that the gangue minerals and harmful impurities (e.g., SiO2, Al2O3, MgO, CaO, S, P, etc.) in the iron ore are removed before they enter the steelmaking furnace(s), which helps to improve the purity of the Fe content in the SPIOP and subsequently leads to a high-quality steel product with low impurities.
The features and advantages of the present methods and systems are further understood in view of the following examples.
In the following experiments, four iron ore concentrate samples were tested and purified to produce four different SPIOP samples, each being purified to approximately 99% (Tables 1-4). The different SPIOP samples were then reduced by hydrogen and melted in a high-temperature electrical hydrogen tube furnace. The final products are mild steels, each having over 99% Fe content with very low impurities such as Si, Al, S, and P (Tables 5-8). These tests validate the present steelmaking methods. Table 9 compares the chemical compositions of the final mild steel products from Tables 5-8 with common related iron and steel products.
The testing results of SPIOP-making are shown in Tables 1-4.
It can be seen from Table 1 that the total impurities content in iron ore concentrate (hematite) sample 1 dropped from 6.50% to 0.73%, which means 88.77% impurities have been removed before entering the steelmaking furnace. Table 1 also shows that the iron ore concentrate sample 1 was purified from 93.5% to 99.27%. This purified product (SPIOP) here, as with for the following examples, can then be used as a raw material for the steelmaking steps of the process of the present application.
Table 2 shows that the total impurities content in the iron ore concentrate (hematite) sample 2 dropped from 9.76% to 0.94%, which means 90.34% impurities were removed before entering the steelmaking furnace. Moreover, the iron ore concentrate sample 2 was purified from 90.24% to 99.06% to form the SPIOP.
The results in Table 3 show that, for iron ore concentrate (hematite) sample 3, the harmful components (Al2O3, S, P) were decreased nearly to zero (trace). The total impurities content in the sample 3 were lowered to 1.29% from 12.48%, which means 89.66% impurities were removed before entering into the steelmaking furnace. The iron ore concentrate sample 3 was purified from 87.52% to 98.71% to form the SPIOP product.
Table 4 displays that, for the iron ore concentrate (hematite) sample 4, the impurities elements (e.g., SiO2, Al2O3, S, P, etc.) were almost completely removed (decreased to trace). The total impurities content in the sample 4 were lowered to 0.99% from 7.42%, which means 86.66% impurities were removed before entering into the steelmaking furnace. The iron ore concentrate sample 4 was purified from 92.58% to 99.01% to make the SPIOP product. The element manganese (Mn) is a useful element in the steel product.
The testing results of H2 steelmaking steps of the process of the present application using the SPIOP products produced from samples 1-4 are shown in Tables 5-8, respectively. The steel production process for the examples of Tables 5-8 is a one-step process that did not use coke, coal, limestone, bentonite, or oxygen-only SPIOP, H2 and electricity. The steelmaking process also emitted zero carbon dioxide (CO2).
Table 5 shows an analysis of the steel produced from the SPIOP of sample 1. The content of impurities elements (e.g. Si, Al, S, P) in the steel is very low (in the level of ppm). The total impurities content is 0.43%, which may contain gas components (e.g. O2, H2, N2, Ar). The total iron content is 99.57%.
Table 6 shows an analysis of the steel produced from the SPIOP of sample 2. The content of impurities elements (e.g., Si, Al, S, P) in the steel is very low (in the level of ppm). The total impurities content is 0.99%, which may contain gas components (e.g. O2, H2, N2, Ar). The total iron content is 99.01%.
Table 7 shows an analysis of the steel produced from the SPIOP of sample 3. The content of impurities elements (e.g., Si, Al, S, P) in the steel is very low (in the level of ppm). The silicon (Si) content is 0.11%. The total impurities content is 0.69%, which may contain gas components (e.g. O2, H2, N2, Ar). The total iron content is 99.31%.
Table 8 shows an analysis of the steel produced from the SPIOP of sample 4. The content of impurities elements (e.g., Si, Al, S, P) in the steel is very low (in the level of ppm). The silicon content is 0.13%. The total impurities content is 0.43%, which may contain gas components (e.g. O2, H2, N2, Ar). The total iron content is 99.10%.
Table 9 shows the comparison of the chemical composition of the steel products of Tables 5-8 and related iron & steel products.
As shown in Table 9, in comparison with typical DRI/sponge iron, which contains approximately 6.5-9.0% iron oxide, approximately 2.8-6.0% gangue, and approximately 0.8-2.5% carbon, the steel products of the present examples have much lower gangue content, much lower iron oxide content, much lower carbon content, and much higher iron content. Similarly, in comparison with typical pig iron, which contains approximately 0.5-6.0% manganese (Mn), approximately 0.5-3.0% gangue, and approximately 3.0-4.0% carbon, the steel products of the present examples have much lower gangue content, much lower manganese content, much lower carbon content, and much higher iron content. Further, in comparison with other low-carbon steel, which contains 0˜0.20% carbon, steel products of the present examples, which are produced via a “green” process, have lower or similar impurities, and thus similar chemical compositions.
It is to be understood that not all components and/or steps described and illustrated with reference to the figures are required for all embodiments or arrangements. Further, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “including,” “comprising,” or “having,” “containing,” “involving,” and variations thereof herein, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It should be noted that use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.
Notably, the figures and examples above are not meant to limit the scope of the present disclosure to a single implementation, as other implementations are possible by way of interchange of some or all the described or illustrated elements. Moreover, where certain elements of the present disclosure can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present disclosure are described, and detailed descriptions of other portions of such known components are omitted so as not to obscure the disclosure. In the present specification, an implementation showing a singular component should not necessarily be limited to other implementations including a plurality of the same component, and vice versa, unless explicitly stated otherwise herein. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. Further, the present disclosure encompasses present and future known equivalents to the known components referred to herein by way of illustration.
The foregoing description of the specific implementations will so fully reveal the general nature of the disclosure that others can, by applying knowledge within the skill of the relevant art(s), readily modify and/or adapt for various applications such specific implementations, without undue experimentation, without departing from the general concept of the present disclosure. Such adaptations and modifications are therefore intended to be within the meaning and range of equivalents of the disclosed implementations, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance presented herein, in combination with the knowledge of one skilled in the relevant art(s). It is to be understood that dimensions discussed or shown are drawings according to one example and other dimensions can be used without departing from the disclosure.
The subject matter described above is provided by way of illustration only and should not be construed as limiting. Various modifications and changes can be made to the subject matter described herein without following the example embodiments and applications illustrated and described, and without departing from the true spirit and scope of the invention encompassed by the present disclosure, which is defined by the set of recitations in the following claims and by structures and functions or steps which are equivalent to these recitations.
