An integrated iron-making and steelmaking site with improved circularity and reduced carbon footprint and a process of producing liquid steel on said site

Abstract

The invention relates to an integrated iron-making and steelmaking site with a reduced carbon footprint and improved circularity of the natural resources and to a process for producing iron and steel with a reduced carbon footprint and improved circularity of the natural resources.

Description

[0001] AN INTEGRATED IRON-MAKING AND STEELMAKING SITE WITH IMPROVED CIRCULARITY AND REDUCED CARBON FOOTPRINT AND A PROCESS OF PRODUCING

[0002] LIQUID STEEL ON SAID SITE

[0003] Field of the invention

[0004] The invention relates to an integrated iron-making and steelmaking site with a reduced carbon footprint and improved circularity of the natural resources and to a process for producing iron and steel with a reduced carbon footprint and improved circularity of the natural resources.

[0005] Background of the invention

[0006] A typical lay-out of a conventional integrated iron- and steelmaking site consists of several key components, including one or more blast furnaces, one or more steelmaking furnaces (such as a basic oxygen furnace or an electric arc furnace), and various supporting facilities. At the heart of the site is the blast furnace, where iron ore, coke, and limestone are fed into the top of the furnace, and hot air is blown into the bottom. This process leads to the reduction of the iron ore to molten iron, which is then tapped from the furnace and transported to the steelmaking furnace. The steelmaking furnace refines the molten iron into steel by removing impurities and adjusting the composition to meet specific requirements.

[0007] The function of the Basic Oxygen Steelmaking (BOF) process, also known as the basic oxygen furnace (BOF) process, is to convert liquid pig iron and steel scrap into high-quality steel through a high-speed, oxygen-blown process. The BOF-process is a primary method for producing steel in integrated steel plants and is known for its efficiency and ability to produce large quantities of steel. During the BOF-process, a vessel called a basic oxygen furnace is charged with liquid pig iron and steel scrap. High- purity oxygen is then blown into the furnace at supersonic speeds, which initiates several key reactions:

[0008] • Oxidation of Impurities: The oxygen reacts with impurities such as carbon, silicon, and manganese, causing them to oxidize and form slag, which is then removed from the surface of the molten steel.

[0009] • Carbon Reduction : The oxygen blowing process oxidizes a significant portion of the carbon present in the molten pig iron, reducing the carbon content to the desired level for the specific grade of steel being produced.

[0010] • Alloying and Temperature Control : Alloying elements, such as ferroalloys, can be added during the BOF process to achieve the desired composition and properties of the steel. Additionally, the exothermic nature of the oxidation reactions helps to raise the temperature of the molten steel to the appropriate level for casting.

[0011] The BOF-process is known for its speed and efficiency in producing large quantities of steel with precise control over the composition and properties. It is widely used in the production of high-quality carbon and low-alloy steels for a wide range of applications, including construction, automotive manufacturing, and infrastructure. Secondary metallurgy in ladle furnaces or vacuum degassing equipment is used to refine the composition of the molten iron from the blast furnace by adjusting the temperature and removing impurities through processes such as desulfurization, dephosphorization, and alloying. This helps in achieving the desired steel composition and properties. In some steelmaking processes, a vacuum degasser is used to remove dissolved gases, such as hydrogen and nitrogen, from the molten steel. This helps in improving the steel's cleanliness and reducing the risk of defects. Argon Injection: Argon is often injected into the molten steel to stir and homogenize the composition, remove non-metallic inclusions, and facilitate the removal of impurities. Alloy Additions: Secondary metallurgy involves adding alloying elements, such as manganese, chromium, nickel, and others, to achieve the desired steel grade and properties. Secondary metallurgy also includes the management and treatment of slag, which is the by-product of the steelmaking process. Slag can be used to remove impurities from the steel and protect the refractory lining of the ladle.

[0012] The raw materials for the ironmaking process are usually provided by coke ovens to provide the coke to support the burden in the blast furnace and to provide the reductant, by a sinter or pellet plant to provide the iron ore in a suitable form. Other important raw materials such as lime and scrap are normally supplied to the site from elsewhere.

[0013] Overall, a conventional integrated iron- and steelmaking site is a complex industrial facility with multiple interconnected processes working together to produce various grades of steel from raw materials.

[0014] Beside the iron and steel products these sites also produce desirable and less desirable by-products. Blast furnace slag is very useful as a raw material for cement production. On the other hand, steelmaking slag is less widely appreciated as a raw material for re-use.

[0015] One by-product that has been in the focus of attention the last couple of years is CO2. As a result of the "Paris Agreement under the United Nations Framework Convention on Climate Change" much research has been done into possibilities for reducing the CO2-emissions, either by capturing and storage of the CO2 (CCS), e.g. in empty gas-fields or by capturing and use of the CO2 (CCU), e.g. in greenhouses for food production.

[0016] Objectives of the invention

[0017] It is the object of this invention to propose configuration for an iron and steelmaking site that enables a significant reduction in CO2 emissions in combination with a flexible operation aimed at improving the circularity of the site.

[0018] It is also an object of this invention to improve the circularity of scrap and reverts.

[0019] It is also an object of this invention to improve the circularity of (post-)transition metals. It is also an object of this invention to limit the amount of undesirable solid byproducts.

[0020] It is also an object of this invention to increase the use of renewable or green feedstock, such as carbon, hydrogen, methane and electricity It is also an object of this invention to enable CO2 and CO removal from the offgas from the various key components of the iron and steelmaking site

[0021] It is also an object of this invention to realise full CO2 utilization.

[0022] Description of the invention

[0023] One or more objectives of the invention is reached by an integrated iron-making and steelmaking site comprising a first liquid iron production plant (IPP1) and a second iron production plant (IPP2) and at least one Basic Oxygen Steelmaking plant (BOF) wherein the integrated site is capable of producing liquid iron in a first process route in the IPP1 and in a second process route in the IPP2, wherein the first process route comprises i). at least one electric arc furnace (EAF) able to operate under oxidising conditions and / or at least one submerged electric arc furnace able to operate under reducing conditions (ESF) and ii). a HIsarna plant as the IPP1 for producing a first liquid iron stream, and wherein the second process route comprises the second iron production plant IPP2 for producing a second iron stream, wherein the second process route comprises a gas-based direct reduction plant (DRP) for producing a direct reduced iron product (DRI) for further processing in the second process route, and optionally an electric arc furnace (EAF) able to operate under oxidising conditions for melting the direct reduced iron product and / or an Electric Smelting Furnace (ESF) for smelting the direct reduced iron product an electric arc melting facility to melt the direct reduced iron, wherein the first and second iron stream can be further processed in the BOF-plant into liquid steel having its final properties for casting into a cast and solidified steel product.

[0024] It is noted that the iron stream from the first process route is a liquid iron stream. The iron stream from the second process route is either a solid iron stream if the DRI produced in the DRP is not melted before feeding it into the BOF, or it may be a liquid iron stream if the DRI is molten before feeding it into the BOF. To enable the use of the DRI as to function as coolant in the BOF converter the DRI has to be solid.

[0025] HIsarna® is a Tata Steel registered trademark. HIsarna is a smelting-reduction technology for ironmaking as described in, e.g., W02020 / 193086 and a schematic process diagram is shown in Figure 1. The process consists of a smelt cyclone and a smelting reduction vessel (SRV). Iron ore is injected into the smelt cyclone, together with oxygen. Hot CO rich gas from the SRV is combusted in the smelt cyclone, increasing the temperature and causing the iron ore to melt and partly pre-reduce. Pre-reduction rates of up to 27% can be achieved in this stage of the process. The molten and partly reduced iron ore will form a liquid film along the wall of the cyclone after which it drops down into the slag layer in the SRV. In this slag layer granular coal is injected. The injection of the coal is required to fully reduce the iron ore to liquid iron and carburize the iron bath. The reduction reaction produces CO gas. This is partly combusted with oxygen in the space between the top of the slag and bottom of the cyclone to generate heat. The splash and turbulence resulting from the injection processes ensure part of this heat is transported to the slag and metal bath. The HIsarna process uses typically oxygen of 95-99 % purity and has therefore an almost nitrogen free top gas. Furthermore the process gas is fully utilized in the process with all the CO and H2 converted to CO2 and H2O when the gas leaves the furnace. The CO2 in the top gas is therefore highly concentrated and this makes the process ideal for a combination with CO2 capture and use or storage, CCU(S). The produced hot metal (= liquid iron) is continuously tapped through the fore-hearth, whilst slag is intermittently tapped through the slag notch.

[0026] The main benefits include aspects related to process intensification and high energy efficiency, reduction in CO2 emission from the off-gases. Additionally, there will be a reduction in emissions of dust, SOx, and NOx, and HIsarna offers flexibility with respect to the use of raw materials. Finally, there will be improvement related to circularity through reclaiming reverts (Zn) from waste materials and / or Zn-coated scrap.

[0027] More specifically, HIsarna produces liquid iron with a low-phosphorus and low- silicon content, and it also reduces costs in steelmaking and opens opportunities for new products. The HIsarna process also offers lower capex (capital expenditures) and opex (operational expenditures) as compared to the blast furnace route, and HIsarna has the potential to replace a substantial part of the use of coal by biomass, natural gas, or hydrogen.

[0028] In current integrated iron- and steel sites typically a sinter plant takes care of the FeOx-type reverts produced. In a situation with only DRP and melting facilities, reclaiming of reverts will become challenging. Part of the reverts can possibly be added as briquettes to the DRP, but this may have consequences for the efficiency. An alternative is HIsarna, able to process both sludges and dusts as well as the course reverts. Slag-type reverts can also find their way to the HIsarna reactor. The excess lime of BOF-sludge can be used for optimizing the slag, while EAF-slag can be used as a low-value ore. The final slag is similar to BF-slag and can be used for cement making. In addition, HIsarna is able to produce zinc-oxide (multi-metal), which can find its way to zinc refineries.

[0029] In this layout there are two separate process routes. The first process route has a HIsarna plant and an arc furnace (AF) as its core. The AF, which may be an electric arc furnace (EAF) able to operate under oxidising conditions or a submerged electric arc furnace able to operate under reducing conditions (ESF) or both. In the context of this description AF means EAF and / or ESF. Submerged arc furnace (SAF) or open slag bath furnace (OBSF) are specific modes of operation an electric smelting furnace reducing electric furnaces (ESF) in relation to slags, position of electrodes and heating.

[0030] The second process route operates independently of the first process route. Both process routes provide iron and eventually the iron from both process routes is led to the BOF-plant for further processing. The iron from both process routes may be mixed into one supply of iron to be processed in the BOF-plant, or the iron streams may be treated separately in the BOF-plant depending on the properties of the individual liquid iron and the properties of the liquid steel that is to be produced by the BOF-process. But an essential feature of the invention is that the process first and the second routes are independently operating routes which independently provide an iron stream. The first process route may provide a liquid iron stream from the HIsarna plant, and one iron stream from the AF. These iron streams (one from HIsarna and one from the AF) may be combined before sending the liquid iron to the BOF-plant which jointly form the first liquid stream or sent to the BOF-plant individually.

[0031] One major advantage of this separation of the first process route from the second process route is that the first process route is able to absorb all reverts, slags, dusts and sludges of the two process routes. This is because the HIsarna plant is unequalled in its capacity to absorb the reverts and by-products products of the iron- and steelmaking processes and convert them into useful and commercially interesting byproducts. Besides acting as a giant hoover for the reverts, slags, dusts and sludges it should not be forgotten that the plant also produces significant quantities of high quality liquid iron of a quality similar to blast furnace liquid iron. It should be noted that the reverts, slags, dusts and sludges of the second process routes can be introduced into the first route as feed into the HIsarna plant together with any other reverts, slags, dusts and sludges that are available on the site.

[0032] Preferably the HIsarna plant in the first process route has a nominal annual capacity of at least 0.8 or 1.0 Mt / y of liquid iron. With nominal capacity the capacity is meant when the HIsarna plant is fully used for producing liquid iron. As shown below the capacity to produce liquid iron is reduced when the HIsarna plant is used for processing reverts, slags, dusts and sludges. The nominal capacity should be sufficiently large to guarantee a stable operation. More preferably the nominal annual capacity of said HIsarna plant is at least 1.1 or 1.25 or even 1.5 Mt / y of liquid iron. Preferably the combination of the one or more AF's and the HIsarna plant have a joint production capacity of liquid iron enough to replace a blast furnace.

[0033] Examples of the reverts, slags, dusts and sludges are BOF sludge, BOF-slag, EAF slag, EAF-dust, DRP-dust, calcined BOF-sludge, oily mill scales and BOF dust. In addition, scale formed during the casting process of the liquid steel and scale formed during a hot-rolling or annealing process can also be processed this way.

[0034] By concentrating the treatment of reverts and byproducts and thereby upgrading the reverts and byproducts products into commercially interesting byproducts in one process route means that the need for landfill is significantly reduced. Moreover conventional iron- and steelmaking routes based on the blast furnace process are unable to absorb low value waste products such as AF-slag and BOF-slag. The HIsarna process is able to absorb these slags in its process and converts it into a slag produced similar to blast furnace slag which is very valuable to the cement industry while also reclaiming the lime and the iron contained in the AF-slag and BOF-slag. The conversion of these slags into a BF-type slag requires additional energy. The consequence is that the productivity of the HIsarna plant is about 10% lower. Lime and dolomite are reused in the HIsarna slag, contributing to additional CO2 savings, and a sellable zinc oxide product is produced as well. In addition, reclaiming will avoid landfilling costs. All in all, the increase in circularity is economically feasible and attractive from a sustainability perspective. Reverts can be introduced in the Hlsarna process in various ways. Both BOF- and EAF-slag are either hammered or (air-) granulated, whilst BOF-sludge can be converted into micro-granules. These materials can be co-injected into Hlsarna with iron ore. The dry EAF-dust can be injected in Hlsarna via a lance, e.g. through a door, directly into the melt. Materials like oily mill scales can be dump charged after briquetting e.g. via a scrap chute. By means of a non-binding example a typical menu for including these reverts and slag-types is shown in Table 1.

[0035] Table 1 - Overview of selected reverts for Hlsarna, based on 4 Mt / y output of liquid steel

[0036] Mt, kt and t = million, thousand and one metric ton; 1 ton = 1000 kg.

[0037] In this typical case, a total of about 160 kt / y of hot metal can be recovered from these materials. The amount of zinc recovered in the Hlsarna dust is 10-15 kt / y, mainly originating from galvanized-type scrap.

[0038] Table 2 shows the results of the mass balance calculations for the Hlsarna unit. The CO2-emissions are around 1.6 t CO2 / t of liquid iron, but the use of sustainable biochar incurs no CO2 penalty. The output of the base case Hlsarna unit is 1.1 Mt hot metal (liquid iron) per year, with the liquid containing 4 wt.% carbon. In the reverts- and-slag case a total of 0.52 Mt / y reverts is included, which is typically originating from a 4 Mt / y site including a blast furnace, a BOF and an EAF. The conversion of slag into BF-type slag is explaining the additional energy. The consequence is that the productivity is lowered to an output of 1.0 Mt / y of liquid iron. Lime and dolomite are reused in the Hlsarna slag, contributing to additional CO2 savings, and a sellable zinc oxide product is produced as well. In addition, reclaiming will avoid landfilling costs.

[0039] Table 2 - Hlsarna mass balance calculations (tHM = ton of hot metal (liquid iron)) This shows that a HIsarna process is capable of hoovering up a large quantity of the reverts, including zinc containing reverts and various slag types of the other installations on the site. For a typical 4 Mt / y site, over 500 kt / y of waste materials can be processed in HIsarna. The coal rate increases by 86 kg / ton of hot metal, which can be considered a limited amount. The output of the industrial scale HIsarna plant will be reduced with 10%, but the overall circularity and efficiency of the site increases.

[0040] In addition, as the first process routes not only produces liquid iron in the HIsarna plant, but liquid iron is also produced in this route by scrap melting in an AF. In the AF any zinc-containing scrap, such as galvanised steel scrap, can be used. The zinc evaporates during the melting process and ends up in the AF-dust. This AF dust can be fed to the HIsarna plant. The zinc is oxidised during the HIsarna process and can be separated in the dedusting after the HIsarna plant as ZnO. This ZnO is a valuable byproduct for the zinc industry. The liquid iron from the AF can be further processed in the BOF. The scrap may come from different sources, e.g. : pre-consumer scrap (which is scrap that has never been provided to a customer), shredded scrap is a processed scrap consisting of fragmented or crushed steel scrap obtained by crushing or shredding used automobiles, electronic goods, white goods etc in small pieces, heavy melting scrap obtained by cutting up obsolete structures, external scrap (purchased on the market) and internal scrap (e.g. from rejects from the hot strip mill, cold mill or annealing lines). In addition, by selecting iron ore for the HIsarna plant with as low an amount of undesirable elements as technically and economically possible, the generation of undesired side-products (which can not be upgraded to a valuable byproduct) can be prevented.

[0041] According to the invention the second process route comprises a gas-based direct reduction plant (DRP) for producing a direct reduced iron product (DRI) for further processing in the second process route. The DRI can be further processed as cold DRI, or if possible as hot DRI if there is a direct link between the DRP and the AF, or it can be compacted to HBI (hot briquetted iron) if so desired. In any case this embodiment produces DRI which is a solid product which typically has a metallisation of around or above 90%. This means that the DRI has to be melted to obtain a liquid iron stream for feeding into the BOF. This can be done by feeding the DRI into an AF. Alternatively, the DRI could be used as coolant in the BOF instead of, or in addition to, scrap. Scrap is the usual coolant in the BOF process.

[0042] In an embodiment the second process route comprises an AF, such as an electric arc furnace (EAF) able to operate under oxidising conditions and / or a submerged electric arc furnace able to operate under reducing conditions (ESF) for melting the direct reduced iron product, and in case of melting in an ESF, for further reducing the DRI. The combination of a DRP with an AF is a balanced process for producing liquid iron in a transitioning site.

[0043] In a preferable embodiment the site further comprises a coking plant for producing the coke for the blast furnace and at least part of the process gases for operating the site. The alternative is to have to purchase coke, in which case the site also needs another supply of process gases. In an embodiment comprises one or more iron ore processing plants for preparing iron ore in a suitable size and form for the liquid iron production plants, such as a sinter plant, a pelletizing plant, a milling plant, a coagulation plant or a granulation plant. In case the site does not or no longer comprises a blast furnace, then a coking plant and a sinter plant may not or no longer be required. In the case of using biomass such as biochar as a carbon source it may be useful to have a briquetting plant on site.

[0044] In a preferable embodiment the gas-based direct reduction plant (DRP) is a shaft furnace for producing direct reduced iron, preferably of the Energiron-type.

[0045] In a final embodiment the second process route comprises no blast furnaces but only one or more DRP's and one or more AF's. To enable a final reduction of the remaining unreduced iron oxides in the DRI an ESF can for instance be used. If there is no longer a blast furnace in the second process route then any remaining sinter capability and coking capability becomes obsolete.

[0046] According to a second aspect the invention is also embodied in a process of producing liquid steel on an integrated iron-making and steelmaking site according to the invention wherein reverts, slags, dusts and sludges such as BOF sludge, BOF slag, ESF slag, ESF dust, EAF slag, EAF dust, DRP-dust, calcined BOF-sludge (in Dutch: historisch oxykalk slik), mill scale, oily mill scale, BOF-dust is processed in the first process route in the HIsarna plant, and preferably only in the first process route.

[0047] In case the reverts, slags, sludges and dusts exclusively go through the first process route (meaning that none of the reverts, slags, sludges and dusts are to be processed in the second process route) then there is no need for a sinter plant in the site configuration provided there is also no blast furnace in the second route. If there is a blast furnace in the second process route, then it may be useful to have a sinter plant for preparing (part of) the ore for the BF. Conventionally, many reverts, slags, sludges and dusts are being processed in the sinter plant for re-use in the blast furnace. This has the disadvantage that side-products accumulate in the blast furnace dust and that the amount of side-product to be discarded in landfill is significant. A big disadvantage of this is also that no EAF or BOF slag can be upgraded from a side-product to a valuable byproduct, whereas the first process route can do so in the HIsarna plant.

[0048] By processing the reverts, slags, sludges and dusts only through the first process route the second process route is relatively "unburdened" whereas the first processing route is ideally suited to absorb the reverts, slags, sludges and dusts due to the capabilities of the HIsarna plant. Specifically the capability to separate (post-)transition metals such as zinc from the AF-dust as zinc oxide and its ability to absorb EAF-slag and BOF-slag and "convert" it via the HIsarna process into a slag similar to BF-slag is very valuable because the zinc can be reused and the HIsarna slag can be used as a resource in the cement industry.

[0049] In an embodiment liquid iron is produced in the first process route in the HIsarna plant from iron ore and liquid iron is produced in the EAF by melting scrap, or in the ESF by smelting DRI, or in the ESF a combination of smelting DRI and melting scrap, and wherein the liquid iron from the HIsarna plant and from the EAF and / or the ESF is sent to the BOF plant stream for further processing into the liquid steel. The scrap melting capability of the AF means that galvanised scrap can be incorporated in the first process route because the HIsarna plant can recuperate the zinc from the AF-dust. The zinc evaporates in the AF and ends up in the AF-dust that is captured. The AF liquid iron and HIsarna liquid iron can be sent to the BOF-plant individually or be combined in a single liquid iron stream and sent to the BOF-plant. Conventional torpedo car transport could be used for that transport to the BOF-plant. In the BOF-plant the liquid iron is further processed to liquid steel and finally cast to produce a cast product. The cast product can be further processed in a known way to hot- and cold rolled steel products.

[0050] In an embodiment the second process route produces direct reduced iron (DRI) in the gas-based direct reduction plant (DRP) wherein the DRI is fed to the EAF and / or ESF for melting and subsequently being directly fed into the combined liquid iron stream and wherein the DRP is run on hydrogen as the reducing gas. In this embodiment it may be advantageous to feed the DRI through the BF because not only is the remaining iron oxide in the DRI reduced to iron, but the liquid metal tapped from the BF then comprises a mixture of DRI iron and BF iron. When the DRP is run on hydrogen as a reducing gas this is an attractive route, because the DRI from a DRP operating with hydrogen as reducing gas is very low on carbon, and feeding the DRI to the BF will result in liquid iron with a high carbon content due to the carbon pick-up in the BF. This may be beneficial in the BOF-operation during the converter process where iron is converted into steel. An ESF is also able to reduce the DRI further, but the ability to increase the carbon level is more limited compared to a BF. Running a DRP on natural gas result in a carbon content in the DRI of typically 1.2 to 2.5 wt.% Natural gas, primarily composed of methane (CH4), is reformed into a reducing gas rich in hydrogen (H2) and carbon monoxide (CO). These gases reduce iron oxides in the shaft furnace. During this process, some carburization occurs, where carbon from CO and CH4 diffuses into the iron, forming cementite (FesC) or dissolving as elemental carbon. In a hydrogen run DRP there is essentially no carbon available and consequently the DRI is extremely low on carbon.

[0051] In an embodiment in the first process route carbon from a renewable source, such as in the form of biochar, is added to the EAF / ESF or to the HIsarna plant or to both the EAF / ESF and the HIsarna plant. This addition reduces the carbon footprint of the process and decreases the need to use fossil sources of carbon.

[0052] In an embodiment in the second process route a process gas comprising natural gas or hydrogen, or a combination thereof, is used in the gas-based direct reduction plant and / or wherein in the first process route a process gas comprising natural gas, syngas or hydrogen, or a combination thereof, is used in the HIsarna plant, preferably wherein the process gas comprises natural gas, syngas or hydrogen from renewable sources. Most preferably all process gases such as natural gas, syngas or hydrogen are from renewable sources ("green" gases).

[0053] In a preferable embodiment the CO2 that is produced in the gas-based direct reduction plant and / or in the HIsarna plant is captured for storage (CCS) or for further utilisation (CCU). There are many useful chemicals that can be produced on the basis of the CO2 that is produced. Examples are given below. In a preferable embodiment dust that is produced during the scrap melting operation in the EAF / ESF in the first process route is fed into the HIsarna plant for recuperating valuable resources such as zinc in the form of zinc oxide by the dedusting installation after the HIsarna plant.

[0054] In the following some upgrading option which can be used in the site configuration according to the invention and in the process according to the invention are presented.

[0055] Although HIsarna is a coal-based process, adapting to biochar is proven to be relatively easy. The purpose of the coal is three-fold, first carbon is required for the iron reduction process, to add carbon to the hot metal, and part of the carbon is used for heat production. Providing heat can be replaced by using a renewable fuel, such as methane, like (bio-)methane, (bio-)syngas, (green) hydrogen, or a combination of these gases. Burning of these gases will take place in top of the HIsarna reactor, while (bio)coal or (bio)char or biomass is injected in the hot metal.

[0056] Similarly, for the gas based DRP a range of feedstocks can be used. For fuel mainly methane and hydrogen can be used, and as the reducing gas it is possible to use methane, hydrogen, CO, syngas, and other chemicals such as methanol or dimethyl ether (DME).

[0057] Furthermore, three main options exist to provide renewable hydrogen, from water electrolysis or from biomass conversion based on gasification, or pyrolysis of biomass. Renewable hydrogen, methane, and carbon, as bio-syngas, mixture of CO and H2 or as biochar, can be obtained from different biomass conversion process, such as syngas or hydrogen from biomass gasification (without a water-gas shift step), biochar form pyrolysis, and biogas (biogenic CO2 and bio-methane) from anaerobic digestion. Green hydrogen is also required for the green conversion of the carbon-rich off-gases to Cl or C2 chemicals (methane, methanol, syngas, and DME).

[0058] Typically, for biogas, mixture of CO2 and CH4, the composition is around CC>2:CH4 = 30-40 : 70-60 vol%. The CO2 is removed to obtain bio-methane using standard gas separation technology such as absorption, pressure swing adsorption (PSA) or a membrane technology.

[0059] With respect to gas treatment for CO2 removal, two options will prevail. First, in case of a DRP with a CO2-scrubber process, the CO2 can be removed using a chemical absorption process employing an amine-based solvent. Typically, a solvent formulation based on activated MDEA (aMDEA, an aqueous solution of piperazine and methyl diethanol amine) is used for removal of CO2 from a range of gas streams, such as the top-gas (or off-gas) from a direct reduction shaft furnace but also natural gas processing (separating CO2 and H2S from CH4). As solvent formulation in principle an aqueous based MDEA solution with piperazine will be used, which can be tailored by the specific solvent formulation to remove (simultaneously) CO2 and H2S.

[0060] Secondly, for the HIsarna process a pre-treatment step and a CO2 removal step is preferably applied. HIsarna is typically using 95% or 99% purity oxygen for generating heat, resulting in an CC -rich off-gas stream containing over 85 vol% CO2.

[0061] Cryogenic carbon capture based on cooling in combination with compressing technology is an economical feasible option. This cold box has as a major advantage that it does not need of substantial amounts of steam as is required for solvent based CO2 treatment options. Contaminants like NOx and remaining SOx will be condensed to respectively nitric acid and sulfuric acid during interstage cooling between the three compressors. A coal filter will prevent NOx, SOx or gaseous metals to entering the cold box, this will result in a stream with > 99% liquefied CO2. This approach will result in almost zero emissions to the atmosphere, and furthermore when biomass is being used this will make HIsarna a CO2-negative iron-making technology.

[0062] A range of options exist for the treatment of carbon-rich off-gases at an integrated steel works, including gas separation technologies based on absorption, adsorption , and membranes, or combination of these three technologies.

[0063] Besides CO2 also carbon monoxide (CO), is a valuable component that can be recuperated from gas streams such as BF gas, coke oven gas (COG), BOF gas, DRP top gas, EAF off-gas, and HIsarna off-gas. In table 3 an indication of the gas composition for off-gas from the processing unit at an integrated steelworks is shown.

[0064] Table 3. Typical gas composition for gas streams of an integrated steelworks r . BF, BOF, COG, HIsarna, DRP, Cooling Top gas, componentvo|O / o vo|O / o vo|O / o vo|O / o vo|O / o DRp vo|O / o DRp vo|O / o

[0065] CH40 0 23 0 92.5 5.9 6

[0066] H24 3 60 0 43.3 43

[0067] CO2 22 20 1 70 7.3 7

[0068] CO 23 54 4 1 13.6 14

[0069] H2O 4 4 4 4 28.8 28

[0070] CxHy 0 0 2 0 0

[0071] N246 18 6 22 7.5 1.1 1

[0072] Other(O2, Ar) 1 1 0 3 0 100 sum 100 100 100 100 100

[0073] As a viable option first a gas treatment step for CO2 separation is applied with subsequently a separation step for CO recovery. A typical option will be using an amine- based absorption process for the recovery of CO2 and pressure swing adsorption (PSA) step for recovery of the CO.

[0074] There are several options for the use of renewable or synthetic reducing gases to be applied the iron making process, such as (synthetic) natural gas, syngas (H2 + CO), H2 and CO for the reduction as well as the carburization reactions of the DRI. Additionally, biomass and in particular biochar can be used as well for the carburization reaction, which takes place according to:

[0075] Fe + 3 C = Fe3C (1)

[0076] Overall, the main approach is the integration of a CO2 recycle with the iron reduction and smelting process. One of the purposes is to close the carbon loop by providing makeup gas for the reducing gas, where the reducing gas is used during the reduction of iron ore to direct reduced iron (DRI) or to hot metal (HM). The main option is to have natural gas, mainly methane, as the reducing gas for the DR process and for the HIsarna process, and have additionally methane as cooling gas in the low temperature end of the DR process just prior to discarding the DRI from the DRP.

[0077] Especially for HIsarna a range of options for the carburization are feasible based on the use of renewable carbon to replace fossil carbon. In particular, the following components based on renewable carbon can be used as carburization agents, synthetic natural gas, bio-methane, biomass and biochar, bio-syngas (CO + H2mixture), and CO2or CO -based Cl and C2 chemicals, such as methanol (Cl) and ethylene and dimethyl ether (DME) (C2) chemicals.

[0078] The required amount of carbon for the carburization process is relatively small, to obtain the desired 4 wt.% of carbon, this requires 40 kg carbon per ton of hot metal.

[0079] The various streams of CO2, either from the DR process, HIsarna, or the biogenic CO2from the anaerobic digestion process, can be converted with renewable hydrogen into synthetic natural gas (SNG) and Cl and C2 chemicals, such as methanol (CH3OH), ethylene (C2H4), and DME (dimethyl ether, CH3OCH3).

[0080] Additionally, other options such as use of carbon-rich off-gases to produce longer hydrocarbons, through a Fischer-Tropsch process, to synthesis molecules like kerosine (C13 to C15 hydrocarbon molecules) is also feasible.

[0081] From an iron making process perspective, methane is the most suitable option to achieve reduction and carburization of the DRI pellets. Typical conditions for carburization of DRI pellets require at least 20% CH4 in the gas fed to the DR process, at a pressure in the range of 6 to 8 bar, and a temperature above 1000 °C.

[0082] Several options can be envisaged for CO2-based chemicals, to be used as fuel and / or reducing agent in the iron-making process, including more specifically methane, methanol, and DME.

[0083] To produce methane, so-called synthetic natural gas (SNG), three options are available, that is to start with a CO2rich stream, a CO rich stream, or a stream with both CO2and CO. The synthesis of methane can take place according to the following reactions, where for each option the required amount of hydrogen is added :

[0084] CO2+ 4 H2= CH4+ 2 H2O (2)

[0085] CO + 3 H2= CH4+ H2O (3) a CO2+ b CO + (4a + 3b) H2= (a + b) CH4+ (2a + b) H2O (4)

[0086] For the synthesis of methanol and DME carbon-rich off-gases can be converted to Cl molecules, like methane, but also alcohols like methanol (MeOH, CH3OH) or higher, C2, molecules, like di-methyl ether (DME, CH3OCH3), according to:

[0087] MeOH : a CO2+b CO+(3a+2b) H2= (a+b) CH3OH+(a) H2O (5)

[0088] DME : a CO2+b CO+(3a+2b) H2= 0.5 (a+b) CH3OCH3+O.5 (3a+b) H2O (6)

[0089] Typically, syngas can be used for the synthesis of larger paraffin molecules, using a Fischer-Tropsch catalyst. The general reaction takes place according to: n CO + (2n + 1) H2= Cn H 2n + 2 + n H2O (7) In general, kerosine from Fischer Tropsch synthesis is a mixture of linear paraffins with molecular formula of C13H28, C14H30 and C15H32. Several options can be envisaged for the synthesis of kerosine using a carbon-rich off gas composed of a mixture of CO and CO2 or with mainly CO2. The main option is based on the use of the water-gas shift or - reverse water-gas shift reaction and optimization of the catalyst.

[0090] Lastly electrochemical conversion based on reduction of CO2 and water electrolysis may be available.

[0091] Several options exist to provide hydrogen, carbon monoxide, or syngas through: water electrolysis (alkaline, PEM, or solid oxide electrolyser (SOE)); high temperature co-electrolysis of CO2 and steam using a SOE; high temperature SOE for reduction of CO2 to CO; low temperature electrolysis, reduction, for CO2 solubilized in an electrolyte solution.

[0092] 5.5 Electrochemical conversion

[0093] Synthesis of hydrogen (water electrolysis) or synthesis of carbon monoxide (CO2 reduction):

[0094] Cathode CO2 + 2 e~ = CO + 02“ or H2O + 2 e- = H2 + O2-

[0095] Anode 2 02“ = O2 + 4 e“

[0096] Co-electrolysis

[0097] Cathode CO2 + 4 H++ 4 e- = CO + H2+ H2O

[0098] Anode 2 H2O = 4 H++ O2 + 4 e-

[0099] Overall a CO2 + b H2O = a CO + b H2 + 0.5 (a + b) O2

[0100] The electrochemical conversion steps can used to produce a syngas mixture (with CO + H2, only H2, or only CO) with an adjustable H2:CO ratio. This means that combining water electrolysis with CO2 electrolysis, which will require two separate units or alternatively use a single (high- temperature solid oxide-based) co-electrolysis unit to give a gaseous system with composition anywhere between H2 of 100 vol %, a mixture with any H2 : CO ratio, or CO of 100 vol%.

[0101] Brief description of the drawings

[0102] The invention will be explained by means of the following, non-limiting figures and site configurations and are intended to show the most important building blocks of the site according to the invention. Most feeds, ancillary installations and outputs are not indicated.

[0103] Figure 1 shows a schematic process diagram of the HIsarna process. It also shows where some of the reverts can be introduced in the installation. Liquid iron is tapped at the side of the forehearth. Slag is tapped at the taphole (not shown). Also two points where dusts are recovered from the filtering system are shown. Figure 2 shows a conventional integrated iron- and steel making site comprising 2 BF's and a BOF. Typical CCh-emissions for such a configuration are between 1.8 - 2.4 Mt / t of liquid steel. Internal FeOx-type reverts are recycled via the sinter plant. Either the BOF- or the BF-dust require landfilling or expensive reprocessing due to the concentrated metals. The slag from the blast furnace is tailored for cement making. The slag from the steel shop is still used for low value applications, like road filling. Although integrated sites are highly efficient and well balanced, their high CO2-emissions have to be reduced.

[0104] Figure 3 shows the site and process according to the invention with the separated first and second process routes with a HIsarna plant as IPP1 in the first process route as well as an arc furnace (EAF and / or ESF) and another iron production plant IPP2 in the second process route. The first and second process routes are separated by the dashed boxes to indicate that these are separate routes, Figure 3 also shows the first and the second iron streams which come together before or in the BOF.

[0105] In the schematic figures the introduction of the reverts, slags, dusts and sludges of the second process route into the first second route as feed into the HIsarna plant together with any other reverts, slags, dusts and sludges that are available on the site is not depicted.

[0106] Figure 4 shows a configuration according to the invention comprising the second process route comprising a DRP as IPP2 and a first process route line replacing the BF of figure 2 with a HIsarna and an AF. Enhancing scrap recycling and the introduction of DRP are widely studied for CCh-reduction from ironmaking. In the scenario described here, sinter capacity will remain, but its function for recycling reverts can potentially be taken over by HIsarna. New reverts will be produced, like EAF-slag and -dust. HIsarna is introduced to process BOF-sludge and BOF-slag, as well as EAF-dust and EAF-slag, and a selection of other reverts. The DRI may be molten in an AF (not depicted in Figure 4) before transportation to the BOF or may be used in solid form as input in the BOF as coolant thereby replacing some or all of the scrap that is usually used as coolant in the BOF.

[0107] Figure 5 shows a first process route wherein optionally green reductant is used in the HIsarna plant. The second production route is now complemented with a BF. The DRI is fed to the BOF directly (dot-dashed line) together with the liquid iron from the BF, BOF or may be used in solid form as input in the BOF as coolant thereby replacing some or all of the scrap that is usually used as coolant in the BOF. If the reducing gas in the DRP is predominantly or only hydrogen, some or all of the DRI may be fed into the BF to enrich the DRI with carbon. This is indicated with the arrow "optional".

[0108] Figure 6 shows the same lay-out but now with the use of biomass such as biochar in the AF and / or the HIsarna. In this embodiment the reducing gas in the DRP is NG and there is no need to feed the DRI through the BF.

[0109] Figure 7 shows a future site without any blast furnace presence, and therefore also no coking plant and sinter plant in the second process route.

[0110] Figure 8 shows a glimpse into a green future of the first process route where the first process route is performed in this ideal scenario on the basis of renewable carbon sources, recycled scrap, iron ore and green process gases such as green hydrogen, green methane and green syngas. The liquid iron resulting from this process is subsequently sent to the BOF-plant. Beside the mentioned feeds also "green" produced DRI or HBI could be introduced in the AF, and in case the AF is an ESF, even unreduced DRI-pellets could be used as feed for smelting in the ESF.

[0111] Figure 9 shows the potential use of renewable feedstock in the different plants.

Claims

CLAIMS1. An integrated iron-making and steelmaking site comprising a first liquid iron production plant (IPP1) and a second iron production plant (IPP2) and at least one Basic Oxygen Steelmaking plant (BOF) wherein the integrated site is capable of producing liquid iron in a first process route in the IPP1 and in a second process route in the IPP2, wherein the first process route comprises i). at least one electric arc furnace (EAF) able to operate under oxidising conditions and / or at least one submerged electric arc furnace able to operate under reducing conditions (ESF) and ii). a HIsarna plant as the IPP1 for producing a first liquid iron stream, and wherein the second process route comprises the second iron production plant IPP2 for producing a second liquid iron stream, wherein the second process route comprises a gas-based direct reduction plant (DRP) for producing a direct reduced iron product (DRI) for further processing in the second process route, optionally wherein the second process route comprises an electric arc furnace (EAF) able to operate under oxidising conditions for melting the direct reduced iron product and / or an Electric Smelting Furnace (ESF) for smelting the direct reduced iron product, wherein the first and second iron stream can be further processed in the BOF-plant into liquid steel having its final properties for casting into a cast and solidified steel product.

2. An integrated site according to claim 1 wherein the second process route comprises an electric arc furnace (EAF) able to operate under oxidising conditions for melting the direct reduced iron product and / or an Electric Smelting Furnace (ESF) for smelting the direct reduced iron product.

3. An integrated site according to claim 1 or 2 wherein the integrated iron-making and steelmaking site further comprises at least one blast furnace as a liquid iron production plant in the second process route, wherein the liquid iron is to be further processed in the BOF-plant into liquid steel.

4. An integrated site according to claim 3 wherein the integrated iron-making and steelmaking site further comprises a coking plant for producing the coke for the blast furnace and at least part of the process gases for operating the site.

5. An integrated site according to any one of the preceding claims wherein the site further comprises one or more iron ore processing plants for preparing iron ore in for the liquid iron production plants, such as a sinter plant, a pelletizing plant, a milling plant, a coagulation plant or a granulation plant.

6. An integrated site according to any one of the preceding claims wherein the gasbased direct reduction plant (DRP) is a shaft furnace for producing direct reduced iron.

7. A process of producing liquid steel on an integrated iron-making and steelmaking site as claimed in any one of the claims 1 to 6 wherein reverts, slags, dusts and sludges such as BOF sludge, BOF slag, ESF slag, ESF dust, EAF slag, EAF dust, DRP-dust, calcined BOF sludge, mill scale, oily mill scale, BOF dust, are processed in the first process route in the HIsarna plant, preferably wherein reverts, slags, dusts and sludges are processed exclusively in the first process route.

8. The process according to claim 7 wherein in the first process route carbon from a renewable source, such as in the form of biochar, is added to the EAF / ESF or to the HIsarna plant or to both the EAF / ESF and the HIsarna plant.

9. The process according to claim 7 or 8 wherein in the first process route liquid iron is produced in the HIsarna plant from iron ore, and wherein liquid iron is produced in the EAF by melting scrap or in the ESF by smelting DRI or in the ESF a combination of smelting DRI and melting scrap, and wherein the liquid iron from the HIsarna plant and from the EAF and / or the ESF is sent to the BOF plant stream for further processing into the liquid steel.

10. The process according to any one of claims 7 to 9 wherein in the second process route direct reduced iron is produced in the gas-based direct reduction plant (DRP) wherein the DRI is fed to the EAF and / or ESF for melting and subsequently being directly fed into the combined liquid iron stream.

11. The process according to any one of claims 7 to 10 wherein in the second process route direct reduced iron is produced in the hydrogen gas-based direct reduction plant (DRP) wherein the DRI is fed into a blast furnace for melting the DRI and wherein the molten DRI joins the liquid iron produced in the blast furnace, or ii) wherein the DRI is fed to the EAF and / or ESF for melting and subsequently being directly fed into the combined liquid iron stream, or iii). a combination thereof.

12. The process according to any one of claims 7 to 11 wherein in the second process route a process gas comprising natural gas, syngas or hydrogen, or a combination thereof, is used in the gas-based direct reduction plant and / or wherein in the first process route a process gas comprising natural gas or hydrogen, or a combination thereof, is used in the HIsarna plant, preferably wherein the process gas comprises natural gas, syngas or hydrogen from renewable sources.

13. The process according to any one of claims 7 to 12 wherein the CO2 that is produced in the gas-based direct reduction plant and / or in the HIsarna plant is captured for storage (CCS) or for further utilisation (CCU).

14. The process according to claim 13 wherein the CO2 that is captured for further utilisation (CCU) is converted with renewable hydrogen into synthetic natural gas (SNG) or into Cl and C2 chemicals, such as methanol (CH3OH), ethylene (C2H4), and DME (dimethyl ether, CH3OCH3).

15. The process according to any one of claims 7 to 14 wherein dust that is produced during the scrap melting operation in the EAF / ESF in the first process route is fed into the HIsarna plant for recuperating valuable resources such as zinc in the form of zinc oxide by the dedusting installation after the HIsarna plant.

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