A carbon footprint dynamic allocation method for zinc-containing dust and sludge based on a rotary hearth furnace zinc removal

Abstract

The present application relates to a kind of carbon footprint dynamic allocation method of zinc-containing dust mud based on zinc removal of rotary hearth furnace, including determining steelmaking process carbon accounting boundary and calculating total carbon emission of steelmaking process;Obtain the zinc content of green ball before entering the rotary hearth furnace and the residual zinc content of metallized pellet after rotary hearth furnace roasting, and calculate the zinc removal rate;Determine the carbon accounting boundary of rotary hearth furnace process and calculate the total carbon emission of rotary hearth furnace process;Total carbon emission of rotary hearth furnace process is distributed to zinc oxide and metallized pellet;Calculate the carbon footprint corresponding to zinc oxide, and calculate the billet carbon footprint;According to the utilization rate and metallization rate of metallized pellet returned to steelmaking process, the billet carbon footprint is corrected, and the corrected billet carbon footprint is obtained.The carbon footprint dynamic allocation method of zinc-containing dust mud based on zinc removal of rotary hearth furnace designed by the present application can solve the problem that the carbon footprint results of billet and resource product exist deviation caused by the existing allocation method, affect the accuracy of process evaluation, product certification and enterprise internal emission reduction decision.

Description

Technical Field

[0001] This invention relates to the technical field of carbon footprint accounting and evaluation of zinc-containing dust and sludge resource utilization in the iron and steel metallurgical process, specifically to a method for dynamic allocation of the carbon footprint of zinc-containing dust and sludge based on dezincification in a rotary hearth furnace. Background Technology

[0002] As the requirements for low-carbon transformation in the steel industry continue to increase, carbon emission accounting in the steelmaking process has gradually expanded from simply focusing on the main product to a comprehensive evaluation of associated solid by-products and their resource utilization. In particular, zinc-containing dust and sludge generated during converter and electric arc furnace steelmaking processes are not only metallurgical by-products requiring proper disposal, but also contain recoverable components such as zinc, iron, and carbon, providing a basis for further resource utilization. In actual production, relevant enterprises typically send this type of zinc-containing dust and sludge to thermal treatment units for dezincification and reuse, thus forming multiple interconnected product flows such as steel billets, zinc oxide, and metallized pellets. Consequently, the issue of carbon emission attribution exhibits characteristics of cross-process, cross-product, and cross-recycling stages.

[0003] Existing carbon footprint allocation methods, when dealing with multi-product, multi-cycle metallurgical scenarios, typically rely on fixed proportions, substitution assumptions, or market-price-based allocation approaches. These methods struggle to consistently reflect the true physical processes underlying different products, and also fail to fully account for the carbon emission transfer effects of dezincification, metallization, and remelting substitution in resource utilization. When raw material composition, process conditions, or by-product recycling rates change, existing allocation methods often cannot be adjusted synchronously, leading to discrepancies in the carbon footprint results for steel billets and resource-recycled products. This, in turn, affects the accuracy of process evaluation, product certification, and internal emission reduction decisions within enterprises.

[0004] Therefore, existing technologies have shortcomings and need to be improved and developed. Summary of the Invention

[0005] The present invention provides a method for dynamic allocation of the carbon footprint of zinc-containing dust and sludge based on dezincification in a rotary hearth furnace. This method addresses the problem that existing allocation methods are often difficult to adjust synchronously, leading to deviations in the carbon footprint results of steel billets and resource-based products, which in turn affect the accuracy of process evaluation, product certification, and internal emission reduction decisions.

[0006] This invention provides a method for dynamic allocation of the carbon footprint of zinc-containing dust and sludge based on rotary hearth furnace dezincification, comprising:

[0007] Obtain material consumption data, energy consumption data, and product output data for the steelmaking process, determine the carbon accounting boundary for the steelmaking process, and calculate the total carbon emissions of the steelmaking process;

[0008] Obtain the zinc content of the green pellets before they are fed into the rotary hearth furnace and the residual zinc content of the metallized pellets after calcination in the rotary hearth furnace, and calculate the dezincification rate;

[0009] Obtain material consumption data, energy consumption data, zinc oxide yield, metallized pellet yield, zinc oxide carbon content, and metallized pellet carbon content when the rotary hearth furnace processes zinc-containing dust and sludge; determine the carbon accounting boundary of the rotary hearth furnace process and calculate the total carbon emissions of the rotary hearth furnace process.

[0010] Based on the zinc oxide yield, the metallized pellet yield, the zinc oxide carbon content, and the metallized pellet carbon content, the total carbon emissions of the rotary hearth furnace process are allocated to zinc oxide and metallized pellets.

[0011] Based on the amount of zinc-containing dust and sludge generated by the steel billet production unit and the carbon content of the zinc-containing dust and sludge, calculate the carbon footprint corresponding to the resource-based production of zinc oxide from the zinc-containing dust and sludge, and calculate the carbon footprint of the steel billet accordingly.

[0012] Based on the utilization rate and metallization rate of the metallized pellets returned to the steelmaking process, the carbon footprint of the billet is corrected to obtain the corrected carbon footprint of the billet.

[0013] Furthermore, the steelmaking process includes a converter steelmaking process and an electric arc furnace steelmaking process; wherein, the converter dust and sludge produced by converter steelmaking and the electric arc furnace dust produced by electric arc furnace steelmaking are all treated as zinc-containing dust and sludge; the carbon accounting boundary of the steelmaking process includes the production system, auxiliary system and energy system, and the production system, auxiliary system and energy system include at least hot metal pretreatment, hot metal smelting, ladle baking, ladle baking, flue gas purification and recovery, dust removal, water treatment and steel slag treatment.

[0014] Furthermore, the total carbon emissions from the steelmaking process are calculated using the following formula:

[0015] ;

[0016] in, The total carbon emissions from 1 ton of steel billet produced in the steelmaking process are expressed in kgCO2 / t.

[0017] fuel or carbon-containing materials Activity data, in t / t or m 3 / t;

[0018] fuel or carbon-containing materials The carbon emission factor, expressed in kgCO2 / t or kgCO2 / m³. 3 ;

[0019] The data represents the activity of the electrodes, in t / t.

[0020] The carbon emission coefficient of the electrode is expressed in kgCO2 / t.

[0021] Data for electricity and heat activities, in kWh / t or GJ / t;

[0022] Carbon emission coefficients for electricity and heat, expressed in kgCO2 / kWh or kgCO2 / GJ;

[0023] For the final product Activity data, in t / t;

[0024] For the final product The carbon emission factor, expressed in kgCO2 / t, refers to the final product. Carbon-containing products output within the carbon accounting boundary of the steelmaking process include at least one of the following according to the actual output type: steel billet, steel product, steel slag, and dust collector ash.

[0025] Furthermore, the step of obtaining the zinc content of the green pellets before they enter the rotary hearth furnace and the residual zinc content of the metallized pellets after calcination in the rotary hearth furnace, and calculating the dezincification rate, includes:

[0026] The zinc content of the green pellets and the residual zinc content of the metallized pellets were determined by chemical titration or XRF spectroscopy.

[0027] Calculate the dezincification rate: ;

[0028] in, For the zinc removal rate, in continuous production conditions, The weighted average value within the corresponding statistical period is used;

[0029] The zinc content of raw pellets before rotary hearth furnace production is expressed in % (%).

[0030] The residual zinc content of the metallized pellets is expressed in percent.

[0031] Furthermore, data on material consumption, energy consumption, zinc oxide yield, metallized pellet yield, carbon content of zinc oxide, and carbon content of metallized pellets are obtained when the rotary hearth furnace processes zinc-containing dust and sludge. The carbon accounting boundary for the rotary hearth furnace process is determined, and the total carbon emissions of the rotary hearth furnace process are calculated, including:

[0032] The carbon accounting boundary of the rotary hearth furnace process includes the pelletizing system, green pellet drying system, rotary hearth furnace roasting system, zinc oxide collection system, and pellet cooling system;

[0033] The total carbon emissions of the rotary hearth furnace process are calculated according to the following formula:

[0034] ;

[0035] in, The total carbon emissions for treating 1 ton of zinc-containing dust and sludge in the rotary hearth furnace process are expressed in kgCO2 / t.

[0036] fuel or carbon-containing materials Activity data, in t / t or m 3 / t;

[0037] fuel or carbon-containing materials The carbon emission factor, expressed in kgCO2 / t or kgCO2 / m³. 3 ;

[0038] This is activity data for electricity, expressed in kWh / t.

[0039] The carbon emission factor for electricity is expressed in kgCO2 / kWh.

[0040] For the final product Activity data, in t / t;

[0041] For the final product The carbon emission factor, expressed in kgCO2 / t, refers to the final product. Carbon-containing products output within the carbon accounting boundary of the rotary hearth furnace process, including metallized pellets and zinc oxide.

[0042] Furthermore, the allocation of the total carbon emissions from the rotary hearth furnace process to zinc oxide and metallized pellets based on the zinc oxide yield, the metallized pellet yield, the zinc oxide carbon content, and the metallized pellet carbon content includes:

[0043] The total carbon emissions from the rotary hearth furnace process are allocated based on the carbon content of zinc oxide and metallized pellets according to the following formula:

[0044] ;

[0045] in, Carbon emissions allocated to 1 ton of zinc oxide, expressed in kgCO2 / t;

[0046] Carbon emissions allocated to 1 ton of metallized pellets, expressed in kgCO2 / t;

[0047] The amount of zinc oxide recovered from processing 1 ton of zinc-containing dust is expressed in t / t.

[0048] The yield of metallized pellets obtained from processing 1 ton of zinc-containing dust is expressed in t / t.

[0049] This refers to the carbon content of zinc oxide, expressed as a percentage (%).

[0050] Carbon content of metallized pellets, in %;

[0051] The zinc oxide yield and metallized pellet yield were obtained by the MES system in the rotary hearth furnace production workshop.

[0052] Furthermore, the calculation of the carbon footprint corresponding to the resource-based production of zinc oxide from the zinc-containing dust and sludge based on the amount of zinc-containing dust and sludge generated by the steel billet production unit and the carbon content of the zinc-containing dust and sludge, and the calculation of the carbon footprint of the steel billet accordingly, includes:

[0053] The carbon footprint of zinc oxide production from the zinc-containing dust sludge is calculated using the following formula:

[0054] ;

[0055] in, The carbon footprint of zinc oxide production from zinc-containing dust and sludge generated by steel billet production units is expressed in kgCO2 / t.

[0056] The amount of zinc-containing dust and sludge generated when producing 1 t of steel billet is expressed in t / t.

[0057] The carbon content of zinc-containing dust is expressed in %;

[0058] Carbon oxidation rate;

[0059] The carbon footprint of the steel billet is calculated using the following formula:

[0060] ;

[0061] in, The carbon footprint of steel billets is expressed in kgCO2 / t.

[0062] Furthermore, the carbon footprint of the billet is corrected based on the utilization rate and metallization rate of the metallized pellets returned to the steelmaking process, resulting in a corrected carbon footprint of the billet, including:

[0063] The corrected carbon footprint of the billet is calculated using the following formula:

[0064] ;

[0065] in, The corrected carbon footprint of steel billets is expressed in kgCO2 / t.

[0066] To improve the utilization rate of metallized pellets returned to the steelmaking process;

[0067] The metallization rate of the metallized pellets is obtained directly from the MES system in the rotary hearth furnace production workshop or measured by chemical titration.

[0068] This refers to the amount of molten steel produced, expressed in tons (t).

[0069] Iron content in molten steel;

[0070] The amount of metallized pellets added is expressed in tons (t).

[0071] This refers to the amount of scrap steel, expressed in tons (t).

[0072] Iron content of scrap steel;

[0073] This refers to the amount of molten iron, expressed in tons (t).

[0074] This represents the iron content of the molten iron.

[0075] Beneficial effects:

[0076] As can be seen from the above technical solutions, the present invention provides a method for dynamic allocation of the carbon footprint of zinc-containing dust and sludge based on rotary hearth furnace dezincification, which has the following beneficial effects:

[0077] 1. Establish a unified carbon footprint accounting chain across processes and products: Instead of isolated accounting for steelmaking or rotary hearth furnace processes, this chain incorporates the entire process—from the generation of zinc-containing dust and sludge in steelmaking to the dezincification and by-product / resource recovery process in the rotary hearth furnace, all returning to the steelmaking process—into a single evaluation system. This approach eliminates reliance on empirical judgments regarding carbon emission attribution between steel billets, zinc oxide, and metallized pellets, allowing for tracking and calculation along a continuous data path. For practical production management, this unified chain helps eliminate discrepancies caused by inconsistencies in accounting standards across different workshops and products, resulting in better continuity, verifiability, and management applicability of carbon footprint results.

[0078] 2. Driving allocation results with process parameters improves consistency between allocation results and actual production conditions: Process parameters such as dezincification rate, metallization rate, product carbon content, and recycling utilization are directly incorporated into the allocation and correction formulas, allowing the carbon footprint results to change with operating conditions rather than remaining fixed at a certain empirical coefficient. This approach ensures that the carbon emission attribution between billets and by-products can be adjusted accordingly when raw material composition, roasting effect, product yield, or recycling organization changes. This feature makes the calculation results closer to actual production conditions and more suitable for process management, process diagnosis, and cross-sectional comparisons, avoiding the rigidity problems common in static allocation methods.

[0079] 3. This application enables the reasonable separation of carbon emission burden from resource-based byproducts from the main product, improving the interpretability of billet-side results: In traditional approaches, zinc-containing dust and sludge generated during steelmaking are often not fully incorporated into subsequent resource utilization assessments, or although there are treatment processes, their impact on the carbon footprint of the main product is not systematically fed back. This application first calculates the carbon footprint corresponding to zinc oxide, then deducts it from the steelmaking-side results, and further corrects it by combining it with the remelting of metallized pellets. This forms a relatively complete separation and feedback mechanism, which can transfer part of the carbon burden originally burdened on the billet side to the resource-based products that actually bear this burden, thus making the billet carbon footprint results more consistent with its true position in the entire process.

[0080] 4. Providing an actionable solution for process optimization and low-carbon management: Since many key parameters in this application can be obtained from production records, test results, and manufacturing execution system data, the results can be used not only for post-event accounting but also for process improvement analysis. Enterprises can identify which process variables have a greater impact on the final result by comparing changes in the billet carbon footprint under different dezincification rates, different metallization rates, different production structures, and different recycling methods. This allows for targeted optimization of rotary hearth furnace operating conditions, resource utilization organization methods, and main process recycling strategies. In other words, this solution not only outputs a numerical result but also provides a traceable, comparable, and optimizable decision-making basis for low-carbon management.

[0081] 5. Improves the stability and comparability of product carbon footprint results: The allocation in this application is primarily based on the quality of the process itself, yield, carbon content, and recycling relationships, rather than overly relying on market prices, substitute product settings, or single calorific value. This ensures that even with significant market fluctuations or difficulties in uniformly defining substitution relationships, the results maintain a relatively stable physical process basis. Furthermore, this approach explicitly expresses all variables in the formula, allowing those skilled in the art to compare different time periods, furnace batches, or production lines using the same accounting standards. Therefore, it is more suitable as a consistent methodology for long-term internal management and external green assessments.

[0082] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other.

[0083] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0084] The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0085] Figure 1 This is a flowchart illustrating the overall process of a dynamic allocation method for the carbon footprint of zinc-containing dust and sludge based on rotary hearth furnace dezincification, as described in this application.

[0086] Figure 2 This is a table showing the energy consumption input and output of a converter steelmaking process based on a dynamic allocation method for the carbon footprint of zinc-containing dust and sludge during dezincification in a converter hearth furnace, as described in an embodiment of this application.

[0087] Figure 3 This is a table showing the energy consumption, material input, and output of a rotary hearth furnace based on a dynamic allocation method for the carbon footprint of zinc-containing dust and sludge in a rotary hearth furnace dezincification process, as described in an embodiment of this application. Detailed Implementation

[0088] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0089] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" indicate that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or sets thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0090] With the increase in the proportion of scrap steel, the content of valuable elements in symbiotic products generated during the steelmaking process (such as zinc-containing dust and sludge from electric arc furnaces and converters) has also increased significantly, resulting in a marked increase in their resource utilization value. These zinc-containing dust and sludge are rich in valuable elements such as zinc, iron, and carbon. Direct landfilling not only causes serious waste of resources but also leads to environmental pollution.

[0091] Currently, there is a lack of scientific and reasonable methods for allocating carbon footprint in the carbon footprint accounting of steel enterprises, in order to allocate the co-products generated during the smelting process. This directly affects the accuracy of carbon footprint accounting for both the main steel products and resource-recycled products (zinc oxide, metallized pellets).

[0092] The system expansion method is currently one of the mainstream methods for accounting for symbiotic products. This method simply expands various metallurgical solid wastes, such as zinc-containing dust and sludge, into iron-containing materials or zinc ore for carbon footprint accounting of the main product. However, it ignores the potential carbon reduction value brought by the subsequent resource utilization of these solid wastes (such as zinc recovery through rotary hearth furnace technology), which directly leads to a systematic overestimation of the carbon footprint of the main steel product. The system expansion method also ignores the recycling value inherent in symbiotic products and their substitution effect as equivalent resources.

[0093] Another approach is the economic value allocation method, which primarily allocates carbon emissions from the metallurgical solid waste treatment process based on the market price ratio of steel to resource-based products such as metallurgical solid waste. The main problem with this method is that the market prices of co-existing products like metallurgical solid waste are highly susceptible to supply and demand fluctuations and market volatility, leading to drastic changes in the weighting of their carbon footprint allocation. This results in a lack of stability and comparability in the carbon footprint calculations for steel and co-existing products, making it difficult to reflect their inherent physical / chemical process relationships.

[0094] Existing methods for allocating the carbon footprint of symbiotic products have shortcomings: the system extension method ignores substitution benefits, leading to distorted allocations; the economic value allocation method is affected by market factors, resulting in unstable results; and the recently proposed method based on the heat of by-products faces the challenge of computational bias caused by fluctuations in actual operating parameters. Therefore, steel companies urgently need a carbon footprint allocation method that is computationally convenient and provides stable output results to scientifically address the carbon emission attribution of symbiotic products such as zinc-containing dust and sludge, thus supporting green and low-carbon development and green product certification.

[0095] Therefore, embodiments of the present invention provide a method for dynamic allocation of the carbon footprint of zinc-containing dust and sludge based on rotary hearth furnace dezincification, referring to... Figure 1 ,include:

[0096] Step S102: Obtain material consumption data, energy consumption data, and product output data for the steelmaking process, determine the carbon accounting boundary for the steelmaking process, and calculate the total carbon emissions of the steelmaking process.

[0097] When acquiring data, it can be based on a preset target statistical period or a preset target production batch, thereby reflecting the dynamism of the data source.

[0098] Step S104: Obtain the zinc content of the green pellets before they enter the rotary hearth furnace and the residual zinc content of the metallized pellets after roasting in the rotary hearth furnace, and calculate the dezincification rate.

[0099] Step S106: Obtain material consumption data, energy consumption data, zinc oxide yield, metallized pellet yield, zinc oxide carbon content, and metallized pellet carbon content when the rotary hearth furnace processes zinc-containing dust and sludge, determine the carbon accounting boundary of the rotary hearth furnace process, and calculate the total carbon emissions of the rotary hearth furnace process.

[0100] When acquiring data, it can be based on a preset target statistical period or a preset target production batch, thereby reflecting the dynamism of the data source.

[0101] Step S108: Based on the zinc oxide yield, the metallized pellet yield, the zinc oxide carbon content, and the metallized pellet carbon content, allocate the total carbon emissions of the rotary hearth furnace process to the zinc oxide and the metallized pellets.

[0102] Step S110: Based on the amount of zinc-containing dust and sludge generated by the steel billet production unit and the carbon content of the zinc-containing dust and sludge, calculate the carbon footprint corresponding to the resource-based production of zinc oxide from the zinc-containing dust and sludge, and calculate the carbon footprint of the steel billet accordingly.

[0103] Step S112: Based on the utilization rate and metallization rate of the metallized pellets returned to the steelmaking process, the carbon footprint of the billet is corrected to obtain the corrected carbon footprint of the billet.

[0104] A complete accounting and allocation path has been established overall. Instead of treating the steelmaking and rotary hearth furnace processes as separate entities, it first obtains the initial baseline carbon emission values ​​for the steelmaking side, then obtains the dezincification and product data for the rotary hearth furnace side. Based on this, the carbon emission allocation of by-products is completed, and then the impact of resource utilization on the carbon footprint of the billet side is fed back to the main product accounting results, ultimately forming the corrected carbon footprint of the billet. In other words, it establishes a dynamic accounting method coupled across processes, rather than a static emission calculation method for a single process.

[0105] By incorporating the resource utilization of zinc-containing dust and sludge, the dezincification effect of rotary hearth furnaces, and the recycling of metallized pellets into the same evaluation chain, byproducts are no longer merely treated as outbound logistics at the steelmaking end. Instead, they are treated as subsequent resource-based products that re-influence the carbon footprint of the main product. This extends carbon emission accounting, which was previously limited to the steelmaking end, to the subsequent resource utilization stage, and feeds back the resource utilization benefits to the billet side results through modified rules. The resulting carbon footprint results are closer to the actual production organization, which is conducive to reflecting the relationship between the main product and byproducts within the same evaluation framework. It also provides a unified data foundation for subsequent process optimization, adjustment of resource utilization ratios, and green evaluation.

[0106] In some embodiments, the steelmaking process includes a converter steelmaking process and an electric arc furnace steelmaking process; wherein, converter dust and sludge generated from converter steelmaking and electric arc furnace dust generated from electric arc furnace steelmaking are all treated as zinc-containing dust and sludge; the carbon accounting boundary of the steelmaking process includes a production system, an auxiliary system, and an energy system, wherein the production system, auxiliary system, and energy system include at least hot metal pretreatment, molten steel smelting, ladle baking, ladle baking, flue gas purification and recovery, dust removal, water treatment, and steel slag treatment.

[0107] Converter dust and sludge from converter steelmaking, and electric arc furnace dust from electric arc furnace steelmaking, all contain zinc and are classified as zinc-containing dust and sludge. Most zinc-containing dust and sludge undergoes dezincification treatment using a rotary hearth furnace. Therefore, when dynamically allocating the carbon footprint of zinc-containing dust and sludge, the steelmaking process must include both converter and electric arc furnace steelmaking.

[0108] First, it is defined that both converter steelmaking and electric arc furnace steelmaking may generate zinc-containing dust and sludge that can be treated. Then, it is further explained that the boundary of the steelmaking process includes not only the direct smelting unit, but also the auxiliary systems and energy systems that are directly related to the target product, so as to ensure that the subsequent carbon emission accounting is not limited to the main furnace in a narrow sense.

[0109] By clearly linking the source of zinc-containing dust and sludge to the boundaries of the steelmaking process, the method provided in this application can be adapted to include by-product streams from different steelmaking routes into the same evaluation system. By pre-defining the process boundaries, boundary disputes during subsequent carbon emission accounting can be reduced, avoiding incomparable results due to the inclusion of units such as baking, dust removal, water treatment, and steel slag treatment. With clear boundaries, the carbon footprint transfer relationship from the steelmaking end to the rotary hearth furnace end is also easier to maintain consistency, which is fundamental to forming stable and verifiable enterprise-level accounting results.

[0110] In some embodiments, the total carbon emissions of the steelmaking process are calculated according to the following formula:

[0111] ;

[0112] in, The total carbon emissions from 1 ton of steel billet produced in the steelmaking process are expressed in kgCO2 / t.

[0113] fuel or carbon-containing materials Activity data, in t / t or m 3 / t;

[0114] fuel or carbon-containing materials The carbon emission factor, expressed in kgCO2 / t or kgCO2 / m³. 3 ;

[0115] The data represents the activity of the electrodes, in t / t.

[0116] The carbon emission coefficient of the electrode is expressed in kgCO2 / t.

[0117] Data for electricity and heat activities, in kWh / t or GJ / t;

[0118] Carbon emission coefficients for electricity and heat, expressed in kgCO2 / kWh or kgCO2 / GJ;

[0119] For the final product Activity data, in t / t;

[0120] For the final product The carbon emission factor, expressed in kgCO2 / t, is the final product. Carbon-containing products output within the carbon accounting boundary of the steelmaking process include at least one of the following according to the actual output type: steel billet, steel product, steel slag, and dust collector ash.

[0121] Emissions from fuels, carbon-containing materials, electrodes, and indirect energy sources are aggregated, while the carbon sequestration carried out by the products is deducted to form the carbon emission results at the steelmaking end, providing a basis for subsequent deduction and correction of the carbon footprint of steel billets.

[0122] By incorporating emissions from different sources during steelmaking and the carbon offset mechanism from products into a single expression, a scalable accounting framework is established. This breaks down the formation mechanism of carbon emissions from the steelmaking side into several traceable components, facilitating the identification of which material, energy, and carbon sequestration items have a significant impact on the final result. This component-based structure not only aids in subsequent allocation calculations but also helps enterprises in practical management to correlate energy-saving and carbon-reduction measures with specific energy sources, materials, or byproducts, thereby enhancing the interpretability and manageability of the method's results.

[0123] In some embodiments, obtaining the zinc content of the green pellets before they enter the rotary hearth furnace and the residual zinc content of the metallized pellets after calcination in the rotary hearth furnace, and calculating the dezincification rate, includes:

[0124] The zinc content of the green pellets and the residual zinc content of the metallized pellets were determined by chemical titration or XRF spectroscopy.

[0125] Calculate the dezincification rate: ;

[0126] in, For the zinc removal rate, in continuous production conditions, The weighted average value within the corresponding statistical period is used;

[0127] The zinc content of raw pellets before rotary hearth furnace production is expressed in % (%).

[0128] The residual zinc content of the metallized pellets is expressed in percent.

[0129] First, the zinc content of raw pellets before entering the furnace and the residual zinc content of metallized pellets after roasting are obtained through detection methods. Then, the dezincification rate is calculated using the relationship between the two, and this parameter is used as a key input for subsequent carbon footprint allocation and zinc oxide carbon footprint calculation. By incorporating the dezincification efficiency as a crucial dynamic parameter directly affecting carbon footprint attribution, the carbon emission attribution on the zinc oxide and billet sides is no longer fixed but adjusts according to the rotary hearth furnace treatment effect. In this way, the carbon footprint results can reflect the resource recovery level as operating conditions change, avoiding static treatment that ignores process effects and providing a clear direction for enterprises to improve overall evaluation results by enhancing dezincification efficiency.

[0130] In some embodiments, based on a preset target statistical period or a preset target production batch, material consumption data, energy consumption data, zinc oxide yield, metallized pellet yield, zinc oxide carbon content, and metallized pellet carbon content are obtained when the rotary hearth furnace processes zinc-containing dust and sludge. The carbon accounting boundary for the rotary hearth furnace process is determined, and the total carbon emissions of the rotary hearth furnace process are calculated, including:

[0131] The carbon accounting boundary of the rotary hearth furnace process includes the pelletizing system, green pellet drying system, rotary hearth furnace roasting system, zinc oxide collection system, and pellet cooling system;

[0132] The total carbon emissions of the rotary hearth furnace process are calculated according to the following formula:

[0133] ;

[0134] in, The total carbon emissions for treating 1 ton of zinc-containing dust and sludge in the rotary hearth furnace process are expressed in kgCO2 / t.

[0135] fuel or carbon-containing materials Activity data, in t / t or m 3 / t;

[0136] fuel or carbon-containing materials The carbon emission factor, expressed in kgCO2 / t or kgCO2 / m³. 3 ;

[0137] This is activity data for electricity, expressed in kWh / t.

[0138] The carbon emission factor for electricity is expressed in kgCO2 / kWh.

[0139] For the final product Activity data, in t / t;

[0140] For the final product The carbon emission factor, expressed in kgCO2 / t, refers to the final product. Carbon-containing products output within the carbon accounting boundary of the rotary hearth furnace process, including metallized pellets and zinc oxide.

[0141] The accounting objects, system boundaries, and total carbon emission calculation methods for the rotary hearth furnace process are refined. It is clarified that the rotary hearth furnace process is not a single furnace body, but consists of subsystems such as pelletizing, green pellet drying, roasting, zinc oxide collection, and pellet cooling. The material and energy activity data of these subsystems are then aggregated into the total carbon emissions of the rotary hearth furnace process.

[0142] The rotary hearth furnace resource recovery process should be established as an independent, quantifiable process unit, rather than merely considered an external processing outcome of steelmaking. This gives the byproduct generation process itself a quantitative basis, thus providing a premise for subsequent allocation based on product carbon content.

[0143] Emissions from the rotary hearth furnace side can no longer be evaluated solely based on empirical estimates, but can now generate independent and traceable accounting results. This provides a source basis for the subsequent attribution of carbon emissions from zinc oxide and metallized pellets, and also ensures that the carbon emission transfer relationship between the steelmaking side and the rotary hearth furnace side no longer relies on subjective experience judgments, but rather on recordable process data and formula calculations.

[0144] In some embodiments, allocating the total carbon emissions of the rotary hearth furnace process to zinc oxide and metallized pellets based on the zinc oxide yield, the metallized pellet yield, the zinc oxide carbon content, and the metallized pellet carbon content includes:

[0145] The total carbon emissions from the rotary hearth furnace process are allocated based on the carbon content of zinc oxide and metallized pellets according to the following formula:

[0146] ;

[0147] in, Carbon emissions allocated to 1 ton of zinc oxide, expressed in kgCO2 / t;

[0148] Carbon emissions allocated to 1 ton of metallized pellets, expressed in kgCO2 / t;

[0149] The amount of zinc oxide recovered from processing 1 ton of zinc-containing dust is expressed in t / t.

[0150] The yield of metallized pellets obtained from processing 1 ton of zinc-containing dust is expressed in t / t.

[0151] This refers to the carbon content of zinc oxide, expressed as a percentage (%).

[0152] Carbon content of metallized pellets, in %;

[0153] The zinc oxide yield and metallized pellet yield were obtained by the MES system in the rotary hearth furnace production workshop.

[0154] Based on the already determined total carbon emissions from the rotary hearth furnace process, a further allocation rule between zinc oxide and metallized pellets is given. An allocation coefficient is constructed by combining product yield with product carbon content, completing the transition from total process emissions to product-specific emissions.

[0155] By incorporating indicators directly related to the physicochemical characteristics of the product into the allocation formula, the allocation results are linked to the product's own carbon content, rather than relying on external market prices or substitution assumptions. This approach is closer to the process itself, making the allocation of zinc oxide and metallized pellets in the rotary hearth furnace process more consistent with the physical relationships during product formation. Since the allocation coefficient is affected by both yield and carbon content, this rule reflects both changes in output and product properties, thus providing a more interpretable and comparable basis for the allocation results under different batches and operating conditions.

[0156] In some embodiments, the step of calculating the carbon footprint corresponding to the resource-based production of zinc oxide from the zinc-containing dust and sludge based on the amount of zinc-containing dust and sludge generated by the steel billet production unit and the carbon content of the zinc-containing dust and sludge, and calculating the carbon footprint of the steel billet accordingly, includes:

[0157] The carbon footprint of zinc oxide production from the zinc-containing dust sludge is calculated using the following formula:

[0158] ;

[0159] in, The carbon footprint of zinc oxide production from zinc-containing dust and sludge generated by steel billet production units is expressed in kgCO2 / t.

[0160] The amount of zinc-containing dust and sludge generated when producing 1 t of steel billet is expressed in t / t.

[0161] The carbon content of zinc-containing dust is expressed in %;

[0162] Carbon oxidation rate;

[0163] The carbon footprint of the steel billet is calculated using the following formula:

[0164] ;

[0165] in, The carbon footprint of steel billets is expressed in kgCO2 / t.

[0166] The carbon content of the zinc-containing dust and sludge itself, the zinc removal rate, and the emissions allocated to the zinc oxide side of the rotary hearth furnace are combined to calculate the carbon footprint corresponding to zinc oxide, and the carbon footprint of steel billets is deducted accordingly. First, the carbon burden of zinc-containing dust and sludge generated by the steel billet in the production unit is determined, then the emissions allocated to the zinc oxide side by the resource recovery process are added, and finally this part is deducted from the baseline carbon emissions on the steelmaking side to obtain the new results on the steel billet side.

[0167] By using zinc-containing dust and sludge as an intermediate carrier, a quantifiable transfer relationship can be established between the carbon footprint of zinc oxide and the original carbon emissions of steel billets. This avoids the long-term retention of emissions that should be borne by resource-based byproducts in the steel billet's final product. The resulting carbon footprint of steel billets better reflects the true burden of the main steelmaking product after considering the destination of byproducts, and is also conducive to forming a quantitative understanding of the resource-based value of byproducts within the enterprise.

[0168] In some embodiments, the step of correcting the billet carbon footprint based on the utilization rate and metallization rate of the metallized pellets returned to the steelmaking process to obtain a corrected billet carbon footprint includes:

[0169] The corrected carbon footprint of the billet is calculated using the following formula:

[0170] ;

[0171] in, The corrected carbon footprint of steel billets is expressed in kgCO2 / t.

[0172] To improve the utilization rate of metallized pellets returned to the steelmaking process;

[0173] The metallization rate of the metallized pellets is obtained directly from the MES system in the rotary hearth furnace production workshop or measured by chemical titration.

[0174] This refers to the amount of molten steel produced, expressed in tons (t).

[0175] Iron content in molten steel;

[0176] The amount of metallized pellets added is expressed in tons (t).

[0177] This refers to the amount of scrap steel, expressed in tons (t).

[0178] Iron content of scrap steel;

[0179] This refers to the amount of molten iron, expressed in tons (t).

[0180] This represents the iron content of the molten iron.

[0181] After obtaining the carbon footprint of the billet, the recycling of metallized pellets back to the steelmaking process is further considered, and the carbon footprint of the billet is revised again. The underlying logic is that metallized pellets are not a one-way product that leaves the system at the end, but can be partially returned to the steelmaking process and take on the function of replacing ferrite sources. Therefore, the corresponding carbon emissions should not all be included in the product results on the rotary hearth furnace side, but should be adjusted on the billet side according to the degree of contribution of recycling.

[0182] By incorporating the actual utilization effect of resource-based products after they are returned to the main process into the carbon footprint assessment method, the method is extended from product allocation to cyclical correction, thus expanding from single allocation to cross-process closed-loop accounting.

[0183] The quantified recycling value of metallized pellets is fed back into the billet evaluation results, thus avoiding the evaluation of the billet carbon footprint based on static results that do not consider recycling in actual production scenarios where recycling substitution exists. The corrected results obtained in this way better reflect the impact of material recycling within steel enterprises on the overall carbon burden and are more suitable for guiding process organization and resource synergy optimization.

[0184] Based on a method for dynamically allocating the carbon footprint of zinc-containing dust and sludge in a rotary hearth furnace dezincification process, a specific embodiment is provided below:

[0185] (1) Calculate the total carbon emissions of the converter steelmaking process, based on the production of 1 ton of converter steel billet, and calculate the carbon emissions. Figure 2 The table shows the energy input and output of the converter steelmaking process. The carbon emission coefficients for converter billets and slag are 15.4 kg CO2 / t and 1.1 kg CO2 / t, respectively, both recommended values ​​according to industry standards. The carbon emission coefficient for metallized pellets is: 1000 kg metallized pellets * carbon content of metallized pellets * (44 / 12) * carbon oxidation rate, i.e.: 1000 kg * 0.4% * (44 / 12) * 100% = 14.67 kg CO2 / t.

[0186] Besides the carbon sequestration deduction for zinc-containing dust and sludge, the carbon emissions from steel billets produced in steelmaking are as follows: .

[0187] (2) The zinc-containing dust and sludge produced in steelmaking is dezincified in a rotary hearth furnace. After testing, the zinc content of the green balls is... The residual zinc content of the metallized pellets is 5%. Given a zinc content of 0.6%, calculate the dezincification rate: .

[0188] (3) Calculate the total carbon emissions of the rotary hearth furnace for treating zinc-containing dust and sludge. Based on the treatment of 1 ton of zinc-containing dust and sludge, the energy consumption data is as follows: Figure 3 The table shows the energy consumption, material input and output of the rotary hearth furnace. The carbon emission coefficient of green pellets is: 1000kg green pellets * carbon content of green pellets * (44 / 12) * carbon oxidation rate, that is, 1000kg * 8.3% * (44 / 12) * 100% = 304.3kgCO2 / t.

[0189] but: .

[0190] (4) The total carbon emissions from the rotary hearth furnace are allocated to metallized pellets and zinc oxide. To process 1 t of zinc-containing sludge, 0.6756 t of metallized pellets and 0.0547 t of zinc oxide are obtained, with the metallized pellets accounting for 0.6% and the zinc oxide accounting for 0.05%. Therefore, the carbon footprint of the metallized pellets and zinc oxide produced by the rotary hearth furnace from zinc-containing sludge is as follows:

[0191] ;

[0192] .

[0193] (5) Calculate and allocate the carbon footprint of steel billets and the carbon footprint of zinc oxide produced from zinc-containing solid waste. Approximately 200 kg of zinc-containing dust and sludge are generated from the production of 1 t of steel billets. If it is 3%, then:

[0194] .

[0195] but: .

[0196] (6) Based on the recycling of metallized pellets in the steelmaking process, the carbon footprint of the billet needs to be corrected. This embodiment describes the treatment of metallized pellets in the converter steelmaking process, based on a steel output of 105.5t, an iron content of 95%, and a metallized pellet addition of 5t. The content of iron in the scrap steel is 60%; the amount of scrap steel is 36.7t, and the iron content of the scrap steel is 95%; the amount of molten iron is 75.6t, and the iron content of the molten iron is 97%. Therefore:

[0197] ;

[0198] .

[0199] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A dynamic allocation method of carbon footprint of zinc-containing dust and sludge based on dezincing in a rotary hearth furnace, characterized in that, include: Obtain material consumption data, energy consumption data, and product output data for the steelmaking process, determine the carbon accounting boundary for the steelmaking process, and calculate the total carbon emissions of the steelmaking process; Obtain the zinc content of the green pellets before they are fed into the rotary hearth furnace and the residual zinc content of the metallized pellets after calcination in the rotary hearth furnace, and calculate the dezincification rate; Obtain material consumption data, energy consumption data, zinc oxide yield, metallized pellet yield, zinc oxide carbon content, and metallized pellet carbon content when the rotary hearth furnace processes zinc-containing dust and sludge; determine the carbon accounting boundary of the rotary hearth furnace process and calculate the total carbon emissions of the rotary hearth furnace process. Based on the zinc oxide yield, the metallized pellet yield, the zinc oxide carbon content, and the metallized pellet carbon content, the total carbon emissions of the rotary hearth furnace process are allocated to zinc oxide and metallized pellets. Based on the amount of zinc-containing dust and sludge generated by the steel billet production unit and the carbon content of the zinc-containing dust and sludge, calculate the carbon footprint corresponding to the resource-based production of zinc oxide from the zinc-containing dust and sludge, and calculate the carbon footprint of the steel billet accordingly. Based on the utilization rate and metallization rate of the metallized pellets returned to the steelmaking process, the carbon footprint of the billet is corrected to obtain the corrected carbon footprint of the billet.

2. The carbon footprint dynamic allocation method for zinc-containing dust and sludge based on the dezincing of a rotary hearth furnace according to claim 1, characterized in that, The steelmaking process includes converter steelmaking and electric arc furnace steelmaking; wherein, converter dust and sludge produced by converter steelmaking and electric arc furnace dust produced by electric arc furnace steelmaking are all treated as zinc-containing dust and sludge; the carbon accounting boundary of the steelmaking process includes the production system, auxiliary system and energy system, and the production system, auxiliary system and energy system include at least hot metal pretreatment, molten steel smelting, ladle baking, ladle baking, flue gas purification and recovery, dust removal, water treatment and steel slag treatment.

3. The carbon footprint dynamic allocation method for zinc-containing dust and sludge based on the dezincing of a rotary hearth furnace according to claim 1 or 2, characterized in that, The total carbon emissions from the steelmaking process are calculated using the following formula: ； in, The total carbon emissions from 1 ton of steel billet produced in the steelmaking process are expressed in kgCO2 / t. fuel or carbon-containing materials Activity data, in t / t or m 3 / t; fuel or carbon-containing materials The carbon emission factor, expressed in kgCO2 / t or kgCO2 / m³. 3 ; The data represents the activity of the electrodes, in t / t. The carbon emission coefficient of the electrode is expressed in kgCO2 / t. Data for electricity and heat activities, in kWh / t or GJ / t; Carbon emission coefficients for electricity and heat, expressed in kgCO2 / kWh or kgCO2 / GJ; For the final product Activity data, in t / t; For the final product The carbon emission factor, expressed in kgCO2 / t, refers to the final product. Carbon-containing products output within the carbon accounting boundary of the steelmaking process include at least one of the following according to the actual output type: steel billet, steel product, steel slag, and dust collector ash.

4. The method for dynamic allocation of carbon footprint of zinc-containing dust and sludge based on rotary hearth furnace dezincification according to claim 3, characterized in that, The process of obtaining the zinc content of the green pellets before they enter the rotary hearth furnace and the residual zinc content of the metallized pellets after calcination in the rotary hearth furnace, and calculating the dezincification rate, includes: The zinc content of the green pellets and the residual zinc content of the metallized pellets were determined by chemical titration or XRF spectroscopy. Calculate the zinc removal rate: ; in, For the zinc removal rate, in continuous production conditions, The weighted average value within the corresponding statistical period is used; The zinc content of raw pellets before rotary hearth furnace production is expressed in % (%). The residual zinc content of the metallized pellets is expressed in percent.

5. The method for dynamic allocation of carbon footprint of zinc-containing dust and sludge based on rotary hearth furnace dezincification according to claim 4, characterized in that, Obtain material consumption data, energy consumption data, zinc oxide yield, metallized pellet yield, zinc oxide carbon content, and metallized pellet carbon content for the rotary hearth furnace process of treating zinc-containing dust and sludge. Determine the carbon accounting boundary for the rotary hearth furnace process and calculate the total carbon emissions of the rotary hearth furnace process, including: The carbon accounting boundary of the rotary hearth furnace process includes the pelletizing system, green pellet drying system, rotary hearth furnace roasting system, zinc oxide collection system, and pellet cooling system; The total carbon emissions of the rotary hearth furnace process are calculated according to the following formula: ； in, The total carbon emissions for treating 1 ton of zinc-containing dust and sludge in the rotary hearth furnace process are expressed in kgCO2 / t. fuel or carbon-containing materials Activity data, in t / t or m 3 / t; fuel or carbon-containing materials The carbon emission factor, expressed in kgCO2 / t or kgCO2 / m³. 3 ; This is activity data for electricity, expressed in kWh / t. The carbon emission factor for electricity is expressed in kgCO2 / kWh. For the final product Activity data, in t / t; For the final product The carbon emission factor, expressed in kgCO2 / t, refers to the final product. Carbon-containing products output within the carbon accounting boundary of the rotary hearth furnace process, including metallized pellets and zinc oxide.

6. The method for dynamic allocation of the carbon footprint of zinc-containing dust and sludge based on rotary hearth furnace dezincification according to claim 5, characterized in that, The allocation of total carbon emissions from the rotary hearth furnace process to zinc oxide and metallized pellets based on the zinc oxide yield, the metallized pellet yield, the zinc oxide carbon content, and the metallized pellet carbon content includes: The total carbon emissions from the rotary hearth furnace process are allocated based on the carbon content of zinc oxide and metallized pellets according to the following formula: ； in, Carbon emissions allocated to 1 ton of zinc oxide, expressed in kgCO2 / t; Carbon emissions allocated to 1 ton of metallized pellets, expressed in kgCO2 / t; The amount of zinc oxide recovered from processing 1 ton of zinc-containing dust is expressed in t / t. The yield of metallized pellets obtained from processing 1 ton of zinc-containing dust is expressed in t / t. This refers to the carbon content of zinc oxide, expressed as a percentage (%). Carbon content of metallized pellets, in %; The zinc oxide yield and metallized pellet yield were obtained by the MES system in the rotary hearth furnace production workshop.

7. The method for dynamic allocation of carbon footprint of zinc-containing dust and sludge based on rotary hearth furnace dezincification according to claim 6, characterized in that, The calculation of the carbon footprint corresponding to the resource-based production of zinc oxide from the zinc-containing dust and sludge generated by the steel billet production unit, based on the amount of zinc-containing dust and sludge and the carbon content of the zinc-containing dust and sludge, and the calculation of the carbon footprint of the steel billet accordingly, includes: The carbon footprint of zinc oxide production from the zinc-containing dust sludge is calculated using the following formula: ； in, The carbon footprint of zinc oxide production from zinc-containing dust and sludge generated by steel billet production units is expressed in kgCO2 / t. The amount of zinc-containing dust and sludge generated when producing 1 t of steel billet is expressed in t / t. The carbon content of zinc-containing dust is expressed in %; Carbon oxidation rate; The carbon footprint of the steel billet is calculated using the following formula: ； in, The carbon footprint of steel billets is expressed in kgCO2 / t.

8. The method for dynamic allocation of the carbon footprint of zinc-containing dust and sludge based on rotary hearth furnace dezincification according to claim 7, characterized in that, The carbon footprint of the billet is corrected based on the utilization rate and metallization rate of the metallized pellets returned to the steelmaking process, resulting in a corrected carbon footprint of the billet, including: The corrected carbon footprint of the billet is calculated using the following formula: ； in, The corrected carbon footprint of steel billets is expressed in kgCO2 / t. To improve the utilization rate of metallized pellets returned to the steelmaking process; The metallization rate of the metallized pellets is obtained directly from the MES system in the rotary hearth furnace production workshop or measured by chemical titration. This refers to the amount of molten steel produced, expressed in tons (t). Iron content in molten steel; The amount of metallized pellets added is expressed in tons (t). This refers to the amount of scrap steel, expressed in tons (t). Iron content of scrap steel; This refers to the amount of molten iron, expressed in tons (t). This represents the iron content of the molten iron.

Images