A mathematical model for measuring the carbon footprint of indium ingot smelting process links

Abstract

This invention discloses a mathematical model for calculating the carbon footprint of indium ingot smelting and processing, comprising the following steps: Step S1, determining the carbon footprint calculation target and its functional unit for indium ingot products; Step S2, drawing a production process flow chart for indium ingot products and determining the carbon footprint boundary of indium ingots; Step S3, determining the energy consumption type of each process step in indium ingot smelting and processing and collecting corresponding data; Step S4, selecting carbon emission factors for each energy consumption type in indium ingot smelting and processing based on the activity data of the indium ingot smelting and processing steps; Step S5, constructing a mathematical model for the carbon footprint of indium ingot smelting and processing based on the activity data of each process step in indium ingot smelting and processing and the appropriate carbon emission factors; Step S6, calculating the carbon emission data of each production process step using the constructed mathematical model for the carbon footprint of indium ingot smelting and processing; Step S7, embedding the mathematical model into the constructed mathematical model calculation system for the carbon footprint of indium ingot smelting and processing.

Description

Technical Field

[0001] This invention relates to the field of rare metal indium smelting and processing, and in particular to a mathematical model for calculating the carbon footprint of indium ingot smelting and processing. Background Technology

[0002] Indium, as a rare metal, has limited global reserves, which leads to its high price. The rare metal indium has wide applications in electronics, aerospace, defense, and machinery, making this limited resource highly valued by countries worldwide.

[0003] Currently, primary indium mainly comes from minerals, accounting for a large proportion of the total. To date, no standalone indium deposits have been discovered; it occurs in trace amounts as an associated mineral with zinc, tin, and other minerals. Since indium is primarily extracted as a byproduct of lead and zinc smelting, its smelting and processing require significant energy and material consumption, leading to substantial carbon dioxide emissions, either directly or indirectly, during indium production. However, research on carbon emissions from indium ingots in my country is currently scarce. This is partly because indium ingots are byproducts of lead and zinc minerals, and their production process is complex, involving significant energy and material consumption, making it relatively difficult to measure carbon emissions from byproducts in a symbiotic system. Furthermore, the relatively low production volume of indium ingots often leads to their neglect within the metal smelting industry, further hindering research on their carbon footprint. With the further advancement of carbon emission accounting technologies, especially the refinement of carbon emission allocation methods such as unit process subdivision, closed-loop cycle splitting, segmentation, physicochemical property allocation, and economic value allocation, clear solutions have been developed for measuring carbon emissions from primary and byproducts in symbiotic systems. Therefore, it is necessary to establish a mathematical model and system for calculating the carbon footprint of indium ingot smelting and processing, so as to provide accurate carbon data management for enterprises and regulatory authorities, and at the same time provide accurate data support for energy conservation and carbon reduction in indium ingot smelting and processing.

[0004] The smelting and processing of indium ingots, from the input of refined zinc-indium ore to the output of finished indium ingots, is highly complex. On the one hand, the smelting and processing of indium ingots requires the input of electricity, heat, and materials, resulting in a degree of complexity in materials and energy. On the other hand, the smelting and processing chain of indium ingots is complex, with various by-products generated within each process, making carbon emission allocation difficult. Therefore, establishing a mathematical model and system for calculating the carbon footprint of indium ingot smelting and processing is of significant practical importance. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A mathematical model for calculating the carbon footprint of indium ingot smelting and processing includes the following steps:

[0007] Step S1: Determine the carbon footprint measurement target and its functional unit for indium ingot products;

[0008] Step S2: Draw the production process flow diagram of indium ingot products and determine the carbon footprint boundary of indium ingots;

[0009] Step S3: Determine the energy consumption type of each process in the indium ingot smelting and processing and collect the corresponding data, and organize the data information of energy consumption type.

[0010] Step S4: Based on the activity data of the indium ingot smelting and processing process, select the carbon emission factors for each energy consumption type in the indium ingot smelting and processing process.

[0011] Step S5: Construct a mathematical model of the carbon footprint of the indium ingot smelting and processing process based on the activity data of each process step and the appropriate carbon emission factor.

[0012] Step S6: Calculate the carbon emission data of each production process using the constructed mathematical model of the carbon footprint of the indium ingot smelting and processing process to obtain the carbon footprint of the indium ingot product smelting and processing process.

[0013] Step S7: Construct a mathematical model calculation system for the carbon footprint of the indium ingot smelting and processing process. Embed the mathematical model into the system to enable autonomous input of energy consumption type, quantity of energy consumption type and matching carbon emission factor. Obtain carbon emission information of sulfuric acid workshop, electrolytic zinc workshop, rotary kiln workshop and liquid preparation workshop, analyze carbon emission information of energy consumption type, and display carbon footprint information of each process link.

[0014] Furthermore, in step S4, the carbon emission factors for each energy consumption type in the indium ingot smelting and processing stage are selected according to PAS2050 and ISO14067.

[0015] Furthermore, the carbon emission calculation targets in step S1 include: carbon emission data of the indium ingot smelting and processing process, and the flow of the carbon footprint of indium ingot products in each production stage; thereby obtaining key emission sources in the production process and providing intuitive data support for subsequent energy conservation and emission reduction.

[0016] The functional unit for carbon footprint measurement is the carbon emissions of indium ingot products obtained by indium ingot smelting and processing enterprises, expressed as kgCO2eq / kg indium ingot products.

[0017] Furthermore, the boundaries of the carbon footprint in step S2 include: the sulfuric acid workshop unit, the electrolytic zinc workshop unit, the rotary kiln workshop unit, and the liquid preparation workshop unit. That is, the macroscopic definition of the boundary is from the raw material entering the plant to the finished indium ingot leaving the plant.

[0018] Furthermore, in step S3, the relevant data collection is completed through surveys, and the collected data includes data from the sulfuric acid workshop unit, the electrolytic zinc workshop unit, the rotary kiln workshop, and the liquid preparation workshop.

[0019] The data for the sulfuric acid workshop unit represents the energy consumption of the production activities of that workshop unit, including transportation energy consumption and energy consumption type. Transportation energy consumption is classified according to transportation equipment, and energy consumption type includes electrical energy consumed in mineral crushing and dust collection, gasoline consumed in material transfer, and diesel and standard coal consumed in the roasting process.

[0020] The data for the electrolytic zinc workshop unit represents the energy consumption of the production activities of that workshop unit, including the energy consumption for calcined sand transportation, calcined sand grinding, leaching water, leaching reaction stirring, transfer pump transportation, filter press operation, flotation water, and flotation machine operation.

[0021] The data for the rotary kiln workshop represents the energy consumption of the equipment used in the workshop, including transportation energy consumption, material preparation energy consumption, combustion energy consumption, rotary kiln rotation energy consumption, and dust removal energy consumption. Among them, transportation energy consumption includes pump conveying energy consumption and belt conveying energy consumption; material preparation energy consumption is the electrical energy consumed by grab bucket material preparation; combustion energy consumption is the anthracite consumed by the rotary kiln during roasting; rotary kiln rotation energy consumption is the electrical energy consumed when the motor drives the rotary kiln; and dust removal energy consumption is the electrical energy consumed by the electrostatic precipitator during operation.

[0022] The data for the liquid preparation workshop represents the energy consumption of the equipment in that workshop unit, including the energy consumption of grinding machinery, the energy consumption of agitators, the energy consumption of filtration operations, and the energy consumption of electric furnace smelting.

[0023] Furthermore, in step S5, the constructed mathematical model of the carbon footprint of the indium ingot smelting and processing process also includes collected on-site carbon emission items, custom-added carbon emission items, and corresponding measured carbon emission factors. The remaining carbon emission equivalent coefficients are derived from the default values ​​in the *IPCC Greenhouse Gas Inventory Guidelines (2009)*, the *Guidelines for Accounting and Reporting Greenhouse Gas Emissions of Enterprises (Power Generation Facilities)* (Environmental Office Climate

[2021] No. 9), and the *Guidelines for Accounting and Reporting Greenhouse Gas Emissions of Enterprises in Other Industrial Sectors (Trial)*. Please refer to Table 1 for the corresponding carbon emission equivalent coefficients.

[0024] Table 1 Carbon Emission Coefficients for Various Energy Resources

[0025]

[0026] Further, in step S5, the mathematical model of the carbon footprint of the indium ingot smelting and processing stage is constructed as follows:

[0027] In the formula: This refers to the carbon dioxide emitted directly and indirectly to the outside world during the indium ingot smelting and processing process, expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This represents the total carbon emissions from indium ingots produced in the sulfuric acid workshop, liquid preparation workshop, rotary kiln workshop, and electrolytic zinc workshop. This represents the total carbon emissions from byproducts of indium ingot production, including sulfuric acid, zinc ingots, and kiln slag. The carbon content in the slag, fly ash, and leaked coal after standard coal combustion;

[0028] The carbon emissions of indium ingot smelting and processing in each workshop unit are as follows:

[0029] (1) Sulfuric acid workshop unit, the calculation formula is:

[0030] In the formula: The total carbon emissions per kilogram of indium ingot in the sulfuric acid workshop unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). The energy consumption types for indium ingots in the sulfuric acid workshop include gasoline, diesel, electricity, and standard coal. Carbon emission factor matched to the type of working fluid consumed by indium ingots;

[0031] (2) Electrolytic Zinc Workshop Unit: The energy consumption of this workshop unit includes calcined sand transportation, calcined sand grinding, leaching water, leaching reaction stirring, conveying pump transportation, filter press operation, flotation water selection, and flotation machine operation. Therefore, the main energy consumption types of this workshop are electrical energy and fresh water. The calculation formula is as follows:

[0032] In the formula: The total carbon emissions per kilogram of indium ingot in the electrolytic zinc workshop unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This refers to the electrical energy consumed in each process step within the electrolytic zinc workshop unit for indium ingots. The carbon emission factor of grid electricity; The amount of fresh water consumed in the electrolytic zinc workshop process; Carbon emission factors for fresh water;

[0033] (3) For the rotary kiln workshop, the calculation formula is as follows:

[0034] In the formula: The total carbon emissions per kilogram of indium ingot in the rotary kiln unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This refers to the electrical energy consumed in each process step within the rotary kiln workshop unit for indium ingots. The amount of fresh water consumed in the process steps of the rotary kiln workshop; Carbon emission factors for fresh water; This refers to the amount of coal consumed as fuel, expressed in tons. Carbon content of standard coal, expressed in tons of carbon per ton of fuel; The oxidation rate of standard coal is expressed in % (%).

[0035] (4) Liquid preparation workshop unit, the calculation formula is as follows:

[0036] In the formula: The total carbon emissions per kilogram of indium ingot in the liquid preparation workshop unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This refers to the electrical energy consumed in each process step within the indium ingot preparation workshop unit.

[0037] (5) Carbon emissions from by-products: During the indium ingot smelting process, by-products are produced, meaning the production system involves multiple products. The main by-products of the system include sulfuric acid, zinc ingots, and kiln slag. Since both main and by-products consume energy and materials, the carbon emissions of main and by-products need to be allocated during the carbon emission accounting process. The carbon emissions of each product are calculated by allocation, and the calculation formula is as follows:

[0038] In the formula: Carbon emissions from byproducts in a symbiotic system; Carbon emissions from the byproduct sulfuric acid; Carbon emissions from zinc ingots, a byproduct; Carbon emissions from by-product kiln slag; This refers to the company's total annual sales revenue. This represents the total annual sales value of sulfuric acid. This refers to the total annual sales value of zinc ingots. This represents the total annual sales value of kiln slag.

[0039] (6) Stored carbon: Carbon in solid form; In the combustion process of coal and petroleum products, the actual combustion cannot reach 100%, that is, some carbon does not participate in oxidation, so carbon exists in solid form.

[0040] Due to the adoption of the above technical solution, the technical progress achieved by this invention compared to the prior art is as follows:

[0041] This invention can scientifically, objectively, and comprehensively analyze the carbon footprint of indium ingot smelting and processing, helping indium ingot production enterprises analyze key carbon emission points, identify the direction of carbon emission reduction flow, and quantitatively calculate carbon emission intensity, thereby achieving the goal of low-carbon and green development and further filling the gap in the current carbon footprint measurement of indium ingot smelting and production. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of the carbon footprint boundary of indium ingots, which is a mathematical model for calculating the carbon footprint of indium ingot smelting and processing.

[0044] Figure 2 This is a schematic diagram of the indium ingot production process, which is a mathematical model for calculating the carbon footprint of indium ingot smelting and processing.

[0045] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0046] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms "first," "second," etc., in the specification, claims, and accompanying drawings are used to distinguish different objects and not to describe a particular order. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0047] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0048] Please refer to Figures 1-2 A mathematical model for calculating the carbon footprint of indium ingot smelting and processing includes the following steps:

[0049] Step S1: Determine the carbon footprint measurement target and its functional unit for indium ingot products;

[0050] Step S2: Draw the production process flow diagram of indium ingot products and determine the carbon footprint boundary of indium ingots;

[0051] Step S3: Determine the energy consumption type of each process in the indium ingot smelting and processing and collect the corresponding data, and organize the data information of energy consumption type.

[0052] Step S4: Based on the activity data of the indium ingot smelting and processing process, select the carbon emission factors for each energy consumption type in the indium ingot smelting and processing process.

[0053] Step S5: Construct a mathematical model of the carbon footprint of the indium ingot smelting and processing process based on the activity data of each process step and the appropriate carbon emission factor.

[0054] Step S6: Calculate the carbon emission data of each production process using the constructed mathematical model of the carbon footprint of the indium ingot smelting and processing process to obtain the carbon footprint of the indium ingot product smelting and processing process.

[0055] Step S7: Construct a mathematical model calculation system for the carbon footprint of the indium ingot smelting and processing process. Embed the mathematical model into the system to enable autonomous input of energy consumption type, quantity of energy consumption type and matching carbon emission factor. Obtain carbon emission information of sulfuric acid workshop, electrolytic zinc workshop, rotary kiln workshop and liquid preparation workshop, analyze carbon emission information of energy consumption type, and display carbon footprint information of each process link.

[0056] Furthermore, in step S4, the carbon emission factors for each energy consumption type in the indium ingot smelting and processing stage are selected according to PAS2050 and ISO14067.

[0057] Furthermore, the carbon emission calculation targets in step S1 include: carbon emission data of the indium ingot smelting and processing process, and the flow of the carbon footprint of indium ingot products in each production stage; thereby obtaining key emission sources in the production process and providing intuitive data support for subsequent energy conservation and emission reduction.

[0058] The functional unit for carbon footprint measurement is the carbon emissions of indium ingot products obtained by indium ingot smelting and processing enterprises, expressed as kgCO2eq / kg indium ingot products.

[0059] Furthermore, the boundaries of the carbon footprint in step S2 include: the sulfuric acid workshop unit (indium concentrate → sulfurization roasting furnace process → high-temperature flue gas (zinc-indium roasted sand) → waste heat boiler → electrostatic precipitator → zinc-indium roasted sand), the electro-zinc workshop unit (zinc dust sand, neutral leaching of roasted sand → acid leaching of roasted sand → silver flotation process → leaching residue), the rotary kiln workshop unit (leaching residue → rotary kiln material storage → rotary kiln roasting process → high-temperature flue gas → waste heat furnace → sulfur-containing flue gas (steam) → electrostatic precipitator → secondary zinc oxide powder), and the liquid preparation workshop unit (secondary zinc oxide powder → indium intermediate leaching process → indium precipitation process → indium leaching → indium extraction → indium replacement → indium melting and casting → indium ingot product). That is, the macroscopic definition of the boundary is from raw material entering the plant to finished indium ingot leaving the plant.

[0060] The indium ingot smelting and processing technology is relatively complex. Based on the actual process flow of indium ingot smelting and processing, the energy consumption type information of each process node is analyzed in turn to determine the carbon emission unit of each node. In this way, the production process flow of indium ingot smelting and processing is drawn, and the boundary range of the carbon footprint mathematical model is confirmed.

[0061] Furthermore, in step S3, the relevant data collection is completed through surveys, and the collected data includes data from the sulfuric acid workshop unit, the electrolytic zinc workshop unit, the rotary kiln workshop, and the liquid preparation workshop.

[0062] The data for the sulfuric acid workshop unit represents the energy consumption of the production activities of that workshop unit, including transportation energy consumption and energy consumption type. Transportation energy consumption is classified according to transportation equipment, and energy consumption type includes electrical energy consumed in mineral crushing and dust collection, gasoline consumed in material transfer, and diesel and standard coal consumed in the roasting process.

[0063] The data for the electrolytic zinc workshop unit represents the energy consumption of the production activities of that workshop unit, including the energy consumption for calcined sand transportation, calcined sand grinding, leaching water, leaching reaction stirring, transfer pump transportation, filter press operation, flotation water, and flotation machine operation.

[0064] The data for the rotary kiln workshop represents the energy consumption of the equipment used in the workshop, including transportation energy consumption, material preparation energy consumption, combustion energy consumption, rotary kiln rotation energy consumption, and dust removal energy consumption. Among them, transportation energy consumption includes pump conveying energy consumption and belt conveying energy consumption; material preparation energy consumption is the electrical energy consumed by grab bucket material preparation; combustion energy consumption is the anthracite consumed by the rotary kiln during roasting; rotary kiln rotation energy consumption is the electrical energy consumed when the motor drives the rotary kiln; and dust removal energy consumption is the electrical energy consumed by the electrostatic precipitator during operation.

[0065] The data for the liquid preparation workshop represents the energy consumption of the equipment in that workshop unit, including the energy consumption of grinding machinery, the energy consumption of agitators, the energy consumption of filtration operations, and the energy consumption of electric furnace smelting.

[0066] Furthermore, in step S5, the constructed mathematical model of the carbon footprint of the indium ingot smelting and processing process also includes collected on-site carbon emission items, custom-added carbon emission items, and corresponding measured carbon emission factors. The remaining carbon emission equivalent coefficients are derived from the default values ​​in the *IPCC Greenhouse Gas Inventory Guidelines (2009)*, the *Guidelines for Accounting and Reporting Greenhouse Gas Emissions of Enterprises (Power Generation Facilities)* (Environmental Office Climate

[2021] No. 9), and the *Guidelines for Accounting and Reporting Greenhouse Gas Emissions of Enterprises in Other Industrial Sectors (Trial)*. Please refer to Table 1 for the corresponding carbon emission equivalent coefficients.

[0067] Table 1 Carbon Emission Coefficients for Various Energy Resources

[0068]

[0069] Further, in step S5, the mathematical model for the carbon footprint of the indium ingot smelting and processing stage is constructed as follows:

[0070] In the formula: This refers to the carbon dioxide emitted directly and indirectly to the outside world during the indium ingot smelting and processing process, expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This represents the total carbon emissions from indium ingots produced in the sulfuric acid workshop, liquid preparation workshop, rotary kiln workshop, and electrolytic zinc workshop. This represents the total carbon emissions from byproducts of indium ingot production, including sulfuric acid, zinc ingots, and kiln slag. The carbon content in the slag, fly ash, and leaked coal after standard coal combustion;

[0071] The carbon emissions of indium ingot smelting and processing in each workshop unit are as follows:

[0072] (1) Sulfuric acid workshop unit, the calculation formula is:

[0073] In the formula: The total carbon emissions per kilogram of indium ingot in the sulfuric acid workshop unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). The energy consumption types for indium ingots in the sulfuric acid workshop include gasoline, diesel, electricity, and standard coal. Carbon emission factor matched to the type of working fluid consumed by indium ingots;

[0074] (2) Electrolytic Zinc Workshop Unit: The energy consumption of this workshop unit includes calcined sand transportation, calcined sand grinding, leaching water, leaching reaction stirring, conveying pump transportation, filter press operation, flotation water selection, and flotation machine operation. Therefore, the main energy consumption types of this workshop are electrical energy and fresh water. The calculation formula is as follows:

[0075] In the formula: The total carbon emissions per kilogram of indium ingot in the electrolytic zinc workshop unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This refers to the electrical energy consumed in each process step within the electrolytic zinc workshop unit for indium ingots. The carbon emission factor of grid electricity; The amount of fresh water consumed in the electrolytic zinc workshop process; Carbon emission factors for fresh water.

[0076] (3) For the rotary kiln workshop, the calculation formula is as follows:

[0077] In the formula: The total carbon emissions per kilogram of indium ingot in the rotary kiln unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This refers to the electrical energy consumed in each process step within the rotary kiln workshop unit for indium ingots. The amount of fresh water consumed in the process steps of the rotary kiln workshop; This refers to the amount of coal consumed as fuel, expressed in tons. Carbon content of standard coal, expressed in tons of carbon per ton of fuel; The oxidation rate of standard coal is expressed in % (%).

[0078] (4) Liquid preparation workshop unit, the calculation formula is as follows:

[0079] In the formula: The total carbon emissions per kilogram of indium ingot in the liquid preparation workshop unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This refers to the electrical energy consumed in each process step within the indium ingot preparation workshop unit. It is the carbon emission factor of grid electricity.

[0080] (5) Carbon emissions from by-products: During the indium ingot smelting process, by-products are produced, meaning the production system involves multiple products. The main by-products of the system include sulfuric acid, zinc ingots, and kiln slag. Since both main and by-products consume energy and materials, the carbon emissions of main and by-products need to be allocated during the carbon emission accounting process. The carbon emissions of each product are calculated by allocation, and the calculation formula is as follows:

[0081] In the formula: Carbon emissions from byproducts in a symbiotic system; Carbon emissions from the byproduct sulfuric acid; Carbon emissions from zinc ingots, a byproduct; Carbon emissions from by-product kiln slag; This refers to the company's total annual sales revenue. This represents the total annual sales value of sulfuric acid. This refers to the total annual sales value of zinc ingots.

[0082] This represents the total annual sales value of kiln slag.

[0083] (6) Stored carbon: In the process of burning coal and petroleum products, the actual combustion cannot reach 100% combustion, that is, some carbon does not participate in oxidation, so carbon exists in solid form.

[0084] Experimental Example

[0085] The carbon footprint of the indium ingot smelting and processing process was calculated using the mathematical model proposed in this invention, based on the indium ingot products produced by a certain indium company in Guangxi in 2021-2022. The target was the carbon footprint data of the company's indium ingot smelting and processing process from 2021 to 2023. The calculation results are shown in Table 2.

[0086] Table 2 Carbon Emission Information of an Indium Industry Company in Guangxi

[0087]

[0088]

[0089]

[0090]

[0091] As shown in Table 2, the method of this invention fully considers the various stages of production, as well as the types of energy consumption and carbon emissions involved in each stage, during the carbon footprint calculation of indium ingot smelting and processing. It possesses advanced and guiding significance in terms of the comprehensiveness and precision of carbon footprint calculation in the indium ingot smelting and processing process.

[0092] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A method for measuring and calculating the carbon footprint of an indium ingot smelting process link, characterized by: Includes the following steps: Step S1: Determine the carbon footprint measurement target and its functional unit for indium ingot products; Step S2: Draw the production process flow diagram of indium ingot products and determine the carbon footprint boundary of indium ingots; Step S3: Determine the energy consumption type of each process in the indium ingot smelting and processing and collect the corresponding data, and organize the data information of energy consumption type. Step S4: Based on the activity data of the indium ingot smelting and processing process, select the carbon emission factors for each energy consumption type in the indium ingot smelting and processing process. Step S5: Construct a mathematical model of the carbon footprint of the indium ingot smelting and processing process based on the activity data of each process step and the appropriate carbon emission factor. Step S6: Calculate the carbon emission data of each production process using the constructed mathematical model of the carbon footprint of the indium ingot smelting and processing process to obtain the carbon footprint of the indium ingot product smelting and processing process. Step S7: Construct a mathematical model calculation system for the carbon footprint of indium ingot smelting and processing. Embed the mathematical model into the system to enable autonomous input of energy consumption type, quantity of energy consumption type and matching carbon emission factor. Obtain carbon emission information of sulfuric acid workshop, electrolytic zinc workshop, rotary kiln workshop and liquid preparation workshop, analyze carbon emission information of energy consumption type, and display carbon footprint information of each process link. In step S5, the mathematical model for the carbon footprint of the indium ingot smelting and processing stage is constructed as follows: In the formula: This refers to the carbon dioxide emitted directly and indirectly to the outside world during the indium ingot smelting and processing process, expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This represents the total carbon emissions from indium ingots produced in the sulfuric acid workshop, liquid preparation workshop, rotary kiln workshop, and electrolytic zinc workshop. This represents the total carbon emissions from byproducts of indium ingot production, including sulfuric acid, zinc ingots, and kiln slag. The carbon content in the slag, fly ash, and leaked coal after standard coal combustion; The carbon emissions of indium ingot smelting and processing in each workshop unit are as follows: (1) Sulfuric acid workshop unit, the calculation formula is: In the formula: The total carbon emissions per kilogram of indium ingot in the sulfuric acid workshop unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). The energy consumption types for indium ingots in the sulfuric acid workshop include gasoline, diesel, electricity, and standard coal. Carbon emission factor matched to the type of working fluid consumed by indium ingots; (2) Electrolytic Zinc Workshop Unit: The production activities in this workshop unit mainly include calcined sand transportation, calcined sand grinding, leaching water, leaching reaction stirring, conveying pump transportation, filter press operation, flotation water selection, and flotation machine operation. Therefore, the energy consumption types of this workshop are mainly electrical energy and fresh water. The calculation formula is as follows: In the formula: The total carbon emissions per kilogram of indium ingot in the electrolytic zinc workshop unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This refers to the electrical energy consumed in each process step within the electrolytic zinc workshop unit for indium ingots. The carbon emission factor of grid electricity; The amount of fresh water consumed in the electrolytic zinc workshop process; Carbon emission factors for fresh water; (3) For the rotary kiln workshop, the calculation formula is as follows: In the formula: The total carbon emissions per kilogram of indium ingot in the rotary kiln unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This refers to the electrical energy consumed in each process step within the rotary kiln workshop unit for indium ingots. The amount of fresh water consumed in the process steps of the rotary kiln workshop; This refers to the amount of coal consumed as fuel, expressed in tons. Carbon content of standard coal, expressed in tons of carbon per ton of fuel; The oxidation rate of standard coal is expressed in % (%). (4) Liquid preparation workshop unit, the calculation formula is as follows: In the formula: The total carbon emissions per kilogram of indium ingot in the liquid preparation workshop unit are expressed in kilograms of carbon dioxide equivalent per kilogram of indium ingot product (kgCO2eq / kg indium ingot product). This refers to the electrical energy consumed in each process step within the indium ingot preparation workshop unit. (5) Carbon emissions from by-products: During the indium ingot smelting process, by-products are produced, meaning the production system involves multiple products. The main by-products of the system include sulfuric acid, zinc ingots, and kiln slag. Since both main and by-products consume energy and materials, the carbon emissions of main and by-products need to be allocated during the carbon emission accounting process. The carbon emissions of each product are calculated by allocation, and the calculation formula is as follows: In the formula: Carbon emissions from byproducts in a symbiotic system; Carbon emissions from the byproduct sulfuric acid; Carbon emissions from zinc ingots, a byproduct; Carbon emissions from by-product kiln slag; This refers to the company's total annual sales revenue. This represents the total annual sales value of sulfuric acid. This refers to the total annual sales value of zinc ingots. The total annual sales value of kiln slag; (6) Stored carbon: Carbon in solid form.

2. The method for calculating the carbon footprint of indium ingot smelting and processing as described in claim 1, characterized in that: The boundaries of the carbon footprint in step S2 include: the sulfuric acid workshop unit, the electrolytic zinc workshop unit, the rotary kiln workshop unit, and the liquid preparation workshop unit.

3. The method for calculating the carbon footprint of indium ingot smelting and processing as described in claim 1, characterized in that: In step S3, the relevant data collection was completed through a survey. The collected data included data from the sulfuric acid workshop unit, the electrolytic zinc workshop unit, the rotary kiln workshop, and the liquid preparation workshop.

4. The method for calculating the carbon footprint of indium ingot smelting and processing as described in claim 3, characterized in that: The data for the sulfuric acid workshop unit is the energy consumption of the production activities of the workshop unit, including transportation energy consumption and energy consumption type. Among them, transportation energy consumption is classified according to transportation equipment, and energy consumption type includes electrical energy consumed by mineral crushing and dust collection, gasoline consumed by material transfer, and diesel and standard coal consumed by roasting process. The data for the electrolytic zinc workshop unit is the energy consumption of the production activities of the workshop unit, including the energy consumption of calcined sand transportation, calcined sand grinding, leaching water, leaching reaction stirring, transfer pump transportation, filter press operation, flotation water, and flotation machine operation. The data for the rotary kiln workshop represents the energy consumption of the equipment used in the workshop, including transportation energy consumption, material preparation energy consumption, combustion energy consumption, rotary kiln rotation energy consumption, and dust removal energy consumption. Among them, transportation energy consumption includes pump conveying energy consumption and belt conveying energy consumption; material preparation energy consumption is the electrical energy consumed by grab bucket material preparation; combustion energy consumption is the anthracite consumed by the rotary kiln during roasting; rotary kiln rotation energy consumption is the electrical energy consumed when the motor drives the rotary kiln; and dust removal energy consumption is the electrical energy consumed by the electrostatic precipitator during operation. The data for the liquid preparation workshop represents the energy consumption of the equipment in that workshop unit, including the energy consumption of grinding machinery, the energy consumption of agitators, the energy consumption of filtration operations, and the energy consumption of electric furnace smelting.

5. The method for calculating the carbon footprint of indium ingot smelting and processing as described in claim 1, characterized in that: In step S5, the constructed mathematical model of carbon footprint in the indium ingot smelting and processing process also includes the collected on-site carbon emission items, and custom carbon emission items and corresponding measured carbon emission factors are added.

6. The method for calculating the carbon footprint of indium ingot smelting and processing as described in claim 1, characterized in that: In step S4, the carbon emission factors for each energy consumption type in the indium ingot smelting and processing process are selected according to PAS2050 and ISO14067.

7. The method for calculating the carbon footprint of indium ingot smelting and processing as described in claim 1, characterized in that: The carbon emission measurement targets in step S1 include: carbon emission data of indium ingot smelting and processing, and the flow of indium ingot product carbon footprint in each production stage.

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