Novel process for the smelting of a blend of hot and cold metalliferous feedstock material yielding reduced carbon emissions

Abstract

The invention relates to a process for the smelting of a metalliferous-containing feedstock material. More particularly, the invention relates to a process for the smelting of a blend of hot and cold metalliferous-containing feedstock material yielding a significant reduction in carbon emissions. According to a first aspect of the present invention, there is provided a process for the smelting of a metalliferous-containing feedstock material, the process comprising the steps of: (i) feeding a combination of hot and cold metalliferous-containing feedstock material, reductant and fluxes into an Open Bath Furnace (OBF) by means of a plurality of adjustable feeding chutes, wherein the OBF can be operated in open arc mode (short open and long open arc-controlled mode), brushed arc mode, and immersed arc mode; (ii) heating the hot and cold metalliferous-containing feedstock material, reductant and fluxes in the OBF at a temperature of between 1 400°C to 1 800°C to sufficiently smelt the feedstock material, reductant and fluxes to form a liquid metal product, a liquid slag product and a CO-containing gas; (iii) carburizing the liquid metal product by introducing a source of carbon into the OBF; and (iv) ensuring the continuous feeding of the combination of hot and cold metalliferous- containing feedstock material, reductant and fluxes by means of the adjustable feeding chutes into the OBF to optimize the power-to-feed balance; wherein the liquid metal product has a carbon content of above 4.0% (m / m%) and a silicon content of below 1.5% (m / m%).

Description

[0001] NOVEL PROCESS FOR THE SMELTING OF A BLEND OF HOT AND COLD METALLIFEROUS FEEDSTOCK MATERIAL YIELDING REDUCED CARBON EMISSIONS

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a process for the smelting of a metalliferous-containing feedstock material. More particularly, the invention relates to a process for the smelting of a blend of hot and cold metalliferous-containing feedstock material yielding a significant reduction in carbon emissions.

[0004] BACKGROUND TO THE INVENTION

[0005] Electric Arc Furnaces (EAF) are commonly employed in the art for smelting Direct Reduced Iron (DRI), incorporating slag foaming to cover the arc due to the use of highly conductive scrap steel and DRI.

[0006] In this regard, US 5,611 ,838 discloses a process involving the use of a foamed slag and hollow electrodes within an Electric Arc Open Bath Direct Current Furnace for smelting scrap and DRI steel. This process employs lances for oxygen injection through the furnace shell. However, the process does not provide for low-grade material to be fed into an EAF, in which case low recovery of the target metal and excessive slag production occurs given the oxidizing environment created by the EAF.

[0007] WO 99 / 36581 introduces a dual-furnace system, comprising a kiln for initial ore reduction followed by smelting in an EAF, which aims to optimise the interaction between pre-reduction and smelting. This former disclosure addresses the pre-reduction stage by utilising a rotary hearth, thereby enabling pre-reduction and smelting to occur in two distinct process units. This system involves transferring pellets containing ore and reductants from the pre-reduction furnace to the smelting furnace. Additionally, a linking enclosure is provided to connect these two process units. However, employing two separate units for pre-reduction and smelting adversely affects energy retention within the process. Consequently, this necessitates increased electrical energy input into the smelting furnace, leading to higher operational costs, reduced efficiency, and a negative environmental impact.

[0008] US 2021 / 301359 addresses the integration of a direct reduced iron (DRI) melting step with the DRI production step. Like WO 99 / 36581 , it teaches of two distinct processing units for reduction and melting, consisting of a DRI melting furnace and a direct reduced shaft furnace. A discharge chute connects the discharge exit of the shaft furnace to the inlet of the DRI melting furnace. This chute transports both the DRI and the reducing gas from the shaft furnace, with the reducing gas playing a crucial role in controlling the melting furnace atmosphere to maintain a reducing environment. Notably, the reducing gas is produced by an upstream process and then directed into the EAF. Furthermore, this document teaches the use of a feed screw or rotary feeder to regulate the feed rate of DRI into the melting furnace, which accepts high-grade feeding material. A choke feed discharge is also employed to form piles in accordance with the angle of repose within the DRI melting furnace.

[0009] WO 2023 / 281 153 teaches of a process for processing iron wherein reducing gas from the DRI plant is directed into the EAF for controlling the melting furnace atmosphere. The process focuses on reducing phosphorous content and desulphurisation before the intermediary iron product is introduced into the steel conversion unit. Although this process produces a high carbon product, the high carbon content of between 1% - 4% is associated with high silicon content in the final product making it less desirous since the final product can be regarded as cold. Given the resultant low temperature and high silicon content of the final product, downstream processes will have to both add additional energy and / or perform refining before being able to further process the products as received from the melting furnace. Accordingly, there is a need for minimising the silicon content thereof to facilitate downstream processes.

[0010] Most notably the processes of US 5,61 1 ,838, WO 99 / 36581 and US 2021 / 301359 utilise an EAF to accomplish the smelting process. Most distinctly, an EAF is operated in oxidising environments and utilises slag foaming to achieve reduction of the direct reduced iron, which naturally also implies that some of the target metal resides in oxide form. Moreover, an EAF is geared for being operated in batches which require regular refractory relining often leading to a halt in production, frequent maintenance, and maintenance costs. Furthermore, another disadvantage of an EAF is that it can only accept high-grade feeding material. Where low-grade feeding material is fed to an EAF, excessive slag production occurs resulting in a low recovery rate making EAF’s less adaptable to receiving a varying degree of quality in the feedstock ore.

[0011] Accordingly, the known process routes have not demonstrated high efficiency yields concurrent with the use of low-grade feed material whilst exhibiting reduced carbon emissions. Given these challenges, there is a compelling need for innovative smelting technologies that can efficiently process a wider range of material qualities, demonstrate a lower environmental footprint, are less reliant on intensive downstream processing, and which are capable of operating continuously.

[0012] For purposes of the present specification, it will be appreciated that the following acronyms are used synonymously with the below referenced phrases.

[0013] EAF Electric Arc Furnace

[0014] BF Blast Furnace

[0015] CDRI Cold Direct Reduced Iron

[0016] DCF Direct Current Open Bath Furnace

[0017] DRI Direct Reduced Iron

[0018] HBI Hot Briquetted Iron HDRI Hot Direct Reduced Iron

[0019] OBF Open Bath Furnace

[0020] OSBF Open Slag Bath Furnace

[0021] SAF Submerged-Arc Furnace

[0022] OBJECT OF THE INVENTION

[0023] It is accordingly an object of the present invention to provide a novel process for the smelting of a blend of hot and cold metalliferous-containing feedstock material which overcomes, at least partially, the abovementioned disadvantages and limitations and / or which will provide a useful alternative to existing technology whereby low-grade feed material is used whilst delivering high quality products which are more favourable for downstream processes with a significantly lower carbon footprint and specific energy requirement.

[0024] SUMMARY OF THE INVENTION

[0025] According to a first aspect of the present invention, there is provided a process for the smelting of a metalliferous-containing feedstock material, the process comprising the steps of:

[0026] (i) feeding a combination of hot and cold metalliferous-containing feedstock material, reductant and fluxes into an Open Bath Furnace (OBF) by means of a plurality of adjustable feeding chutes, wherein the OBF can be operated in open arc mode (short open and long open arc-controlled mode), brushed arc mode, and immersed arc mode;

[0027] (ii) heating the hot and cold metalliferous-containing feedstock material, reductant and fluxes in the OBF at a temperature of between 1 400°C to 1 800°C to sufficiently smelt the feedstock material, reductant and fluxes to form a liquid metal product, a liquid slag product and a CO-containing gas;

[0028] (iii) carburizing the liquid metal product by introducing a source of carbon into the OBF; and

[0029] (iv) ensuring the continuous feeding of the combination of hot and cold metalliferous- containing feedstock material, reductant and fluxes by means of the adjustable feeding chutes into the OBF to optimize the power-to-feed balance; wherein the liquid metal product has a carbon content of above 4.0% (m / m%) and a silicon content of below 1 .5% (m / m%).

[0030] The invention provides for the metalliferous-containing feedstock material to be an iron- containing feedstock material.

[0031] Smelting in the present context is to be understood as the process of extracting iron from an iron-containing feedstock material.

[0032] It will be appreciated that the iron-containing feedstock material may be any material, such as an ore, concentrate, scrap, fines, waste materials from steel production value chains or any combination of such materials, which material or combination of materials comprise(s) a metal or metal-containing compound of iron (Fe).

[0033] The iron-containing feedstock material may be pre-reduced iron feedstock material as well as un-reduced iron feedstock material.

[0034] The invention provides for the pre-reduced iron feedstock material to be pre-reduced iron ore. Similarly, the invention provides for the un-reduced iron feedstock material to be un-reduced iron ore.

[0035] The pre-reduced iron ore may be either hot briquetted iron (HBI) or cold DRI (CDRI). The HBI may be crushed HBI (HBI < 20 mm).

[0036] The iron-containing feedstock material may include cold briquetted iron waste (CBI < 20 mm). The iron-containing feedstock material may include waste fines (< 20 mm); mill scale (< 10 mm); pre-reduced iron ore fines (< 10 mm); un-reduced iron ore fines (< 10 mm); and a combination thereof.

[0037] In an embodiment of the invention, the pre-reduced iron ore may be carbon deficient or carbon- free HBI or CDRL It will be appreciated that the pre-reduced iron ore may be low Fe grade HBI or CDRI.

[0038] In a further embodiment of the invention, the pre-reduced iron ore can include recycled scrap.

[0039] The invention further provides for the iron-containing feedstock material to consist of 100% -50 pm iron ore particles.

[0040] The invention provides for a plurality of adjustable feeding chutes which allow for the introduction of the combination of hot and cold iron-containing feedstock blend into the OBF.

[0041] The plurality of adjustable feeding chutes allows for the introduction of the hot and cold iron- containing feedstock blend around a periphery of inner walls of the OBF or around at least one electrode of the OBF.

[0042] The invention provides for low-grade HBI or cold DRI to also be produced with 100% hydrogen to further reduce the CO2 footprint. It will be appreciated that the HBI or CDRI produced with 100% hydrogen will have very low to 0% carbon content.

[0043] The invention provides for continuous replenishment of the iron-containing feedstock material, reductant and fluxes by means of the plurality of adjustable feeding chutes into the OBF to ensure that the loss-in-weight and power-to-feed balance is optimized. The specific energy requirement (SER) of a smelting process can be simply expressed as MWh per metric ton of total feed or power (MW) / feed rate (ton / h). SER is the energy required to transform the feed materials at 25°C into the product streams at the desired temperatures at which they leave the furnace. SER is thus inherently the power-to-feed ratio. It will be appreciated that the theoretical SER changes quite significantly if the chemical composition or temperature of the raw materials deviate from the theoretical baseline.

[0044] In terms of the invention, the DC furnace has a power capacity of up to 100 MW with a typical 400 - 700 kWh / ton of hot metal and typical reductant usage of 45 - 50 kg / ton of hot metal to allow for the liquid metal product produced to have a carbon content of above 4.0%.

[0045] In an embodiment of the invention, the liquid metal product temperature may be between 1330°C - 1550°C.

[0046] In an embodiment of the invention the OBF may be a Direct Current (DC) OBF (DC furnace).

[0047] In an embodiment of the invention, there is provided for the DC furnace to include an insulated copper or steel roof.

[0048] In an embodiment of the invention, the DC furnace consists of at least one electrode.

[0049] The DC furnace, as mentioned above, consists of a plurality of adjustable feeding chutes which allows for the introduction of the hot and cold iron-containing feedstock blend into the DC furnace. These feeding chutes may comprise a single feeder connected to each feeding chute. The DC furnace may comprise any number of feeding chutes, but particularly the DC furnace comprises 4 or 8 feeding chutes. In another preferred embodiment, the DC furnace may comprise 6 or 12 feeding chutes. The invention provides for the reductant to be a low-grade reductant, for instance anthracite, finer fraction coke, or petroleum coke. In an embodiment of the invention, the reductant may be bio-carbon. The reductant may be added to the OBF as particulates having a particle size equal to or less than 0 to 50 mm.

[0050] The flux may be selected from the group consisting of burnt dolomite, burnt limestone, quartzite, bauxite and a combination of one or more thereof.

[0051] In terms of the invention, the liquid metal product material may be formed through the heating and melting or at least partial melting of the iron-containing feedstock material, reductant and fluxes.

[0052] The residence time of the iron-containing feedstock material in the OBF may be controlled to impact the degree of reduction of the iron-containing feedstock material in the OBF.

[0053] In terms of the invention, the slag product may be used downstream in inter alia cement applications.

[0054] The degree of metallization of iron in the iron-containing feedstock material in the process may be from as low as 86% to 94%.

[0055] It will be appreciated that carburization involves taking a low carbon metal product and transforming it into a high carbon metal product. This may be done by exposing the metal product to an atmosphere which is dense in carbon. By heating a metal product in a carbon- dense atmosphere, the metal product will allow carbon atoms to attach to its surface on a molecular level.

[0056] In terms of the present invention, carburization may be achieved by carbon injection in the DC furnace into the hot metal. In an alternative embodiment of the invention, carburization may be achieved in a Torpedo, in hot metal ladles or in a suitable-type vessel.

[0057] In an embodiment of the invention, there is provided for carbon lances to be included in the DC furnace to introduce carbon into the DC furnace to facilitate carburization of the metal product, if necessary.

[0058] It will be appreciated that by using carbon injection, the liquid metal product may be enriched with carbon beyond what is believed possible according to the material balance of the process. From a material balance perspective, to achieve a high carbon content of above 4.0% in the liquid metal product inadvertently also increases the number of impurities, such as silicon, therein, which in turn negatively impacts the high liquid metal product temperature, thus affecting downstream processing.

[0059] It will further be appreciated that given the carburization of the liquid metal product by means of carbon injection which allows for the use of less reductant in the hot and cold iron-containing feedstock blend, it is now surprisingly possible to achieve lower silicon content in the liquid metal product than would otherwise be believed possible without the use of carbon injection.

[0060] The liquid metal product is characterized as per the values provided herein below:

[0061] The present invention provides for a multi-physical computational fluid dynamics model for the reactions, kinetics, and different transformer modes with specific reference to the DC furnace. It will be appreciated that post tap hole operations can be integrated seamlessly in the process of the present invention.

[0062] In view of the above it will be appreciated that taking into account inter alia the process target parameters (as set out in the detailed description below) including the lower specific energy requirement and the ability to operate the OBF at higher energy input (increased power density), lower emission of greenhouse gases is achieved thereby reducing the net carbon footprint of the process to be between 20% and 40% of the traditional BF route.

[0063] It is to be understood that the steps of the process according to the invention need not necessarily be executed sequentially, as the process may be operated in a batch, semi-batch or continuous manner. Furthermore, it is envisaged that the steps of the process provided for need not necessarily be executed in the order listed herein.

[0064] BRIEF DESCRIPTION OF THE DIAGRAMS

[0065] The invention will now further be described, by way of example only, with reference to the accompanying diagrams wherein:

[0066] Figure 1 is a schematic representation of a process for the smelting of a blend of hot and cold metalliferous-containing feedstock material according to the present invention;

[0067] Figure 2 is a cross-sectional front perspective view of adjustable feed chutes as employed in one embodiment of the process of Figure 1 ;

[0068] Figure 3 is a front perspective view of an electrode arm arrangement in a DC furnace as employed in the process of Figure 1 ;

[0069] Figure 4 is a front view of a copper roof design employed in one preferred embodiment of a DC furnace of the process of Figure 1 ;

[0070] Figure 5 is a top perspective view of a twelve-feed chute arrangement employed in one preferred embodiment of an OBF of the process of Figure 1 ; and

[0071] Figure 6 shows a diagram depicting the arc zones within the process of Figure 1 . DETAILED DESCRIPTION OF THE INVENTION

[0072] The invention described herein is not to be limited in scope by any specific embodiment or example herein disclosed, as the embodiments and examples are intended as illustrative of several aspects of the invention. Any equivalent embodiments are intended to be within the scope of this invention, as they will become apparent to those skilled in the art from the present description.

[0073] EXPERIMENTALS

[0074] To exemplify the efficacy of a working embodiment of the present invention, a 1 MW pilot scale DC Furnace, as described according to the first aspect of the invention, was constructed, said DC Furnace being capable of being industrially upscaled.

[0075] A total of 443t of natural gas (NG) reduced DRI in 146 batches of material, producing 127 slag taps and 146 liquid metal product taps totaling 334t of liquid metal product.

[0076] During the testing, parameters such as the SER of the process; the liquid slag parameters; liquid metal product parameters; effect of carbon lance carburization on the liquid metal product; scaling furnace power density to reduce furnace size; the influence of various refractories; and the influence of the various feeding arrangements coupled with various current settings of the OBF (collectively “operating modes”) were evaluated.

[0077] The operating modes tested were as follows:

[0078] 1 . Short Open Arc-Controlled (SOAC) operation with feed distributed on the peripheral of the electrode;

[0079] 2. Short Open Arc-Controlled (SOAC) operation with feed distributed on the peripheral of the furnace sidewall;

[0080] 3. Brush Arc operation with feed distributed on the peripheral of the electrode; 4. Brush Arc operation with feed distributed on the peripheral of the furnace sidewall; and

[0081] 5. Immersed Electrode operation with feed distributed on the peripheral of the furnace sidewall.

[0082] It should be appreciated that the invention is not limited to the above operating modes and is merely indicated to exemplify the invention.

[0083] A total of 7 test conditions following the heat-up and stabilization phase were executed to test the former parameters:

[0084] • Heat-up, ramp-up and stabilization of DC furnace;

[0085] • SOAC (10cm arc length), electrode feed;

[0086] • SOAC (10cm arc length), sidewall feed;

[0087] • Brush-arc, electrode feed;

[0088] • Brush-arc, sidewall feed;

[0089] • Immersed mode; sidewall feed;

[0090] • SOAC (10cm arc length), electrode feed with in-situ carbon injection.

[0091] RESULTS

[0092] A high level of Fe reduction was achieved, resulting in low Fe content in the slag (< 1%). The tapping temperature difference between the liquid metal product and the liquid slag of less than 100°C could only be realised seldomly and is severely impacted by the OBF carbon balance. This in turn would mean that scenarios will exist in the commercial OBF where the slag will exceed the specified temperature of 1 550°C.

[0093] Due to the high superheat levels in the molten products and the relatively low quantity of reductive smelting performed compared to ferroalloy furnaces, the furnace continued to operate and tap despite being in an over-carbon state. In contrast, if a ferroalloy such as ferrochrome were being smelted, the situation would differ markedly. Both the metal product and the slag would likely freeze in the tapholes, preventing tapping from occurring. This highlights the specific operational tolerances and challenges associated with different types of smelting processes and furnace conditions.

[0094] Liquid Slag Product

[0095] Controlling the composition of the liquid slag product was influenced by several key factors:

[0096] 1 ) Fluctuations in the carbon (C) and silicon (Si) content of the liquid metal product, as previously discussed, along with a delay between changes in the furnace input parameters and the resulting impacts.

[0097] 2) Natural variations in the chemical composition of the direct reduced iron (DRI), notably the carbon content.

[0098] 3) The low yield ratio of slag to metal in the process, which means that even a minimal change in a component of the DRI — such as a 0.5% absolute change — can lead to a significant impact, potentially altering the slag composition by more than 2.5%.

[0099] Despite these influencing factors, there were instances where both the temperature of the liquid metal product and the composition of the liquid slag product met target specifications, even amid the fluctuations in the DRI composition. Table 1 below depicts the target slag parameters.

[0100] Table 1 : Target Slag Parameters

[0101] Parameter Target Value [m / m%]

[0102] AI2O3> 10.7 TiO2< 1.25 MnO < 0.4 FeO < 1.0 CaO > 40 SiO2< 36 MgO 5,5< X <8.0 S <1.5

[0103] B2 Basicity (CaO / SiO2) 1.05< Y <1.25

[0104] B3 Basicity

[0105] > 1.3 ((CaO+MgO) / SiO2) Liquid Metal Product

[0106] Without the use of a liquid metal product carburization agent injected through the lance system, an average carbon (C) content of 4.06% and silicon (Si) content of 1 .32% in the liquid metal product was successfully achieved. This was accomplished by maintaining high levels of reductant — up to 8kg per 100kg of DRI — in the furnace feed. Additionally, an average hot metal temperature of 1 381 °C was recorded, which falls below the target temperature of 1450°C.

[0107] It is crucial to recognise that the low metal temperature is primarily due to thermodynamic constraints necessitated by operating with high levels of excess carbon in the feed to reach above the 4.0% carbon threshold. This condition facilitated significant silicon reduction to the liquid metal product. Prolonged periods of over-carbon operation were also observed to cause severe sidewall bank formation, leading to a reduction in the OBF’s crucible size, which rendered this operating state unsustainable in the long term.

[0108] However, surprisingly, by lowering the amount of the reductant fed to the furnace (3.5 - 4.5 kg / 100 kg DRI), lower levels of C, Si, and higher liquid metal product tapping temperatures were unexpectedly achieved. The results achieved by feeding less reductant are depicted in Table 2 below.

[0109] Table 2: Liquid Metal Product Analysis Feeding (3.5 - 4.5 kg / 100 kg DRI) to the OBF By employing pneumatic injection of a liquid metal product carburisation agent through the refractory lining carbon lances, a liquid metal product with lower levels of silicon, higher carbon, and higher tapping temperatures were surprisingly achieved according to line 5 in Table 2, above.

[0110] Operating Modes

[0111] The composition of the liquid metal product is moderately influenced by the operating mode itself. However, this influence is significantly overshadowed by the effects of the furnace reductant (carbon) and the balance between feed and power. Additionally, sidewall feeding plays a crucial role in managing the formation of protective sidewall banks. Despite its benefits, this method occasionally leads to some raw material being expelled from both the liquid slag product and liquid metal product tapholes.

[0112] Furthermore, the pneumatic injection of a carburization material has proven beneficial not only for enhancing the carburization of the liquid metal product but also for improving the heat transfer from the liquid slag product to the liquid metal product. This is primarily due to the mixing induced by the bubbling gas, which helps achieve better tapping temperatures for the liquid metal product.

[0113] Test Conclusion

[0114] The SER of the process was measured and found to be within the design margins set by the SER target value of 465 - 550 kWh / ton of hot metal. In terms of slag production, it was managed within the defined target parameters. Effective and precise control over the slag chemistry and the carbon balance of the furnace are extremely important considerations to achieve target values. Moreover, accurate and diligent monitoring of the DRI composition is crucial, as minor fluctuations in the gangue species and carbon content can significantly affect the chemistry of the liquid slag product and the overall carbon balance.

[0115] The liquid metal product was also produced within the performance target parameters. The in- situ carbon injection system is identified as playing a fundamental and critical role in achieving these targets, specifically regarding the carbon content and temperature of the liquid metal product.

[0116] Various operating modes of the OBF were evaluated. Preferably, the OBF will, predominantly, operate in brush arc or SOAC modes at full power, while immersed operation will only be viable, and possibly necessary, at lower power levels. The design hearth power density for the commercially scaled OBF has been set at 220 kW / mA2 and has proven to be an acceptable and safe level.

[0117] In situ tests of the liquid metal product carburization using a pneumatically injected lance system have shown significant benefits to the operation, as noted in the discussions above on achieving the target parameters. The OBF was also operated at a high-power level to test the feasibility of reducing future OBF furnace sizes, suggesting that an increase in power density could decrease the OBF size and associated capital expenditures.

[0118] A process for the smelting of a hot and cold blend of metalliferous-containing feedstock material according to the invention is generally designated by reference numeral 10 in the accompanying diagrams.

[0119] Figure 1 shows a schematic representation of the process 10 for the smelting of a hot and cold blend of metalliferous-containing feedstock material according to the present invention. As shown in Figure 1 ; HBI, CDRI, waste and fines 20, reductants and fluxes 30 are fed through adjustable feed chutes 40 (Figure 2) into the DCF 50. Here, hot and cold feed material 20 and reductants and fluxes 30 are (where applicable) batched in separate hoppers and proportioned in the adjustable feed chutes 40 (See Figure 5). The loss-in-weight and feed-to-power ratio systems control the furnace feed 20 and 30 and can be charged in the center (hollow-electrode) of the DCF 50, peripheral of the DCF 50 (side feed) or in the high intensity energy zone (close to the electrode) of the DCF 50.

[0120] The high gas velocities around the DCF 50 plasma (not shown) pull the material 20 and 30 in the arc zones (Figure 6) and the DCF 50 is operated with a single or multiple graphite electrode (Figure 3). Furnace operational control is done via a dedicated furnace controller (not shown), a combination of electrode current control, furnace impedance control, furnace resistance control, furnace power input and rectifier control, and very stable furnace operation with the electrode tip (not shown).

[0121] The DCF 50 has a power capacity of up to 100 MW with a typical 400 - 700 kWh / ton hot metal and typical reductant usage 45 - 50 kg / ton pig iron (Aim 0.1 %C to 4.5 %C).

[0122] The furnace 50 itself is constructed from a steel shell with a refractory based containment system that is able to safely contain molten material with temperatures of up to 1 800°C. The furnace 50 includes an insulated copper or steel roof (Figure 4).

[0123] Hot iron 60 (see Table 2 above) and molten slag 70 (see Table 1 above) is tapped from the DCF 50 intermittently and delivered to downstream processes that will produce steel (from hot iron 60) and cement replacement materials (from slag 70). The hot iron 60 as per plant requirement is tapped from a dedicated set of uniquely placed metal and slag tapholes (not shown). The DCF 50 is equipped with carbon lances 80 strategically placed to optimize carbon feed positions for hot iron carburization if necessary.

[0124] Additional carburization could also be done by carbon added in the torpedo.

[0125] The net carbon foot print of this production process 10 is expected to be between 20% and 40% of the traditional BF route.

[0126] Simultaneously, the process 10 provides an improved alternative to existing technology whereby a hot and cold blend of low-grade feed material is used whilst demonstrating a significantly lower carbon footprint with high efficiency yields.

[0127] The description is presented by way of example only in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention and / or the equipment utilized therein in more detail than is necessary for a fundamental understanding of the invention.

Claims

CLAIMS1 . A process for the smelting of a metalliferous-containing feedstock material, the process comprising the steps of:(i) feeding a combination of hot and cold metalliferous-containing feedstock material, reductant and fluxes into an Open Bath Furnace (OBF) by means of a plurality of adjustable feeding chutes, wherein the OBF can be operated in open arc mode (short open and long open arc-controlled mode), brushed arc mode, and immersed arc mode;(ii) heating the hot and cold metalliferous-containing feedstock material, reductant and fluxes in the OBF at a temperature of between 1 400°C to 1 800°C to sufficiently smelt the feedstock material, reductant and fluxes to form a liquid metal product, a liquid slag product and a CO-containing gas;(iii) carburizing the liquid metal product by introducing a source of carbon into the OBF; and(iv) ensuring the continuous feeding of the combination of hot and cold metalliferous- containing feedstock material, reductant and fluxes by means of the adjustable feeding chutes into the OBF to optimize the power-to-feed balance; wherein the liquid metal product has a carbon content of above 4.0% (m / m%) and a silicon content of below 1 .5% (m / m%).

2. The process according to claim 1 , wherein the metalliferous-containing feedstock material is an iron-containing feedstock material.

3. The process according to claim 1 , wherein the iron-containing feedstock material is any material, such as an ore, concentrate, scrap, fines, waste materials from steel production value chains or any combination of such materials, which material or combination ofmaterials comprise(s) a metal or metal-containing compound of iron (Fe).

4. The process according to any one of claims 1 to 3, wherein the iron-containing feedstock material is pre-reduced iron feedstock material.

5. The process according to claim 4, wherein the pre-reduced iron feedstock material is prereduced iron ore.

6. The process according to any one of claims 1 to 3, wherein the iron-containing feedstock material is un-reduced iron feedstock material.

7. The process according to claim 6, wherein the un-reduced iron feedstock material is unreduced iron ore.

8. The process according to claim 5, wherein the pre-reduced iron ore is either hot briquetted iron (HBI) or cold DRI (CDRI).

9. The process according to claim 8, wherein the HBI is crushed HBI (HBI < 20 mm).

10. The process according to any one of claims 1 to 3, wherein the iron-containing feedstock material includes cold briquetted iron waste (CBI < 20 mm).11 . The process according to any one of claims 1 to 3, wherein the iron-containing feedstock material includes waste fines (< 20 mm); mill scale (< 10 mm); pre-reduced iron ore fines (< 10 mm); un-reduced iron ore fines (< 10 mm); and a combination thereof.

12. The process according to claim 5, wherein the pre-reduced iron ore is carbon deficient or carbon-free HBI or CDRI.

13. The process according to claim 5, wherein the pre-reduced iron ore is low Fe grade HBI or CDRI.

14. The process according to claim 12 or 13, wherein the pre-reduced iron ore includes recycled scrap.

15. The process according to claim 1 , wherein the liquid metal product temperature is between 1 330°C - 1 550°C.

16. The process according to claim 1 or 15, wherein the liquid metal product is characterized as per the values provided herein below:

17. The process according to claim 1 , wherein the OBF furnace has a power capacity of up to 100 MW with a typical 400 - 700 kWh / ton of hot metal and typical reductant usage of 45 - 50 kg / ton of hot metal to allow for the liquid metal product produced to have a carbon content of above 4.0%18. The process according to any one of the preceding claims, wherein the process provides for continuous replenishment of the iron-containing feedstock material, reductant and fluxes by means of the plurality of adjustable feeding chutes into the electrothermal furnace to ensure that the loss-in-weight and power-to-feed balance is optimized.

19. The process according to claim 1 , wherein the reductant is a low-grade reductant, forinstance anthracite, finer fraction coke, or petroleum coke.

20. The process according to claim 1 , wherein the flux is selected from the group consisting of burnt dolomite, burnt limestone, quartzite, bauxite and a combination of one or more thereof.

21. The process according to any one of the preceding claims, wherein the degree of metallization of iron in the iron-containing feedstock material in the process is from as low as 86% to 94%.

22. The process according to claim 1 , wherein carburization is achieved by carbon injection in the OBF into the hot metal.

23. The process according to claim 22, wherein carburization is achieved in a Torpedo.

24. The process according to any one of the preceding claims, wherein the net carbon footprint is between 20% to 40% of the traditional BF route.

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