Life cycle carbon footprint determination method for ardealite utilization and disposal

Abstract

The invention belongs to the technical field of carbon emission accounting, and particularly relates to a life cycle carbon footprint determination method for ardealite utilization and disposal, which is characterized in that the whole life cycle of ardealite treatment and disposal is divided into a raw and auxiliary material production stage, a raw and auxiliary material transportation stage, an ardealite harmless stage, an ardealite comprehensive utilization stage and an ardealite stockpiling stage; respectively quantifying to obtain the carbon emission of each stage, namely C production, C transportation, C harmlessness, C utilization and C stockpiling; and calculating to obtain the total carbon emission C in the whole life cycle of phosphogypsum treatment. The method can promote the resource utilization of the phosphogypsum, reduce the influence of the phosphogypsum on the environment, promote the green transformation of related industries, and meet the national sustainable development goal. And the method can also be widely applied to carbon footprint accounting of other industrial byproducts, and a new solution is provided for realizing low-carbon economy. Through effective management and utilization of ardealite, the method provides a feasible technical support for ecological environment protection and resource saving.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy conservation and emission reduction in industrial solid waste treatment and disposal, and specifically relates to a method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal. Background Art

[0002] Phosphogypsum is a byproduct of the phosphate fertilizer and phosphoric acid industries. Its primary component is calcium sulfate dihydrate, with small amounts of impurities. Due to the rapid development of my country's phosphorus chemical industry, phosphogypsum production has continued to increase, with accumulated quantities now reaching 870 million tons. However, the long-term storage of phosphogypsum can cause serious environmental problems, such as the leakage of acidic wastewater and the spread of heavy metal and radioactive contamination, posing a significant threat to surrounding ecosystems. Furthermore, the resource utilization of phosphogypsum faces technical and cost limitations, making the management of its storage and resource utilization a pressing issue.

[0003] Carbon emission accounting is of great significance for assessing the environmental impact of phosphogypsum. In the context of achieving the goals of "carbon peak and carbon neutrality", developing low-carbon technologies and reducing carbon emissions in the treatment of industrial by-products have become the key to the green development of the phosphorus chemical industry. The life cycle carbon footprint assessment of phosphogypsum can reveal its carbon emission characteristics under different treatment and disposal methods, and provide a scientific basis for reducing carbon emissions in the entire phosphorus chemical process. However, there is currently a lack of systematic research on the carbon footprint accounting of phosphogypsum utilization and disposal, making it difficult to fully quantify carbon emissions at each stage of the phosphogypsum treatment and disposal process, which restricts the optimization of carbon emission reduction paths.

[0004] Existing phosphogypsum management mainly focuses on pollution control and resource utilization pathways, but lacks a carbon emission accounting framework covering its entire life cycle. Existing determination methods are mostly used in traditional waste management fields, but due to its unique chemical properties, generation process and pollution characteristics, it is difficult to directly apply these methods to phosphogypsum. In addition, the lack of a systematic carbon emission database and detailed carbon emission factors has led to a large gap in the applicability and accuracy of carbon emission determination methods. Therefore, there is an urgent need to establish a full-life cycle carbon footprint determination method applicable to the utilization and disposal of phosphogypsum, and to construct a scientific and systematic evaluation model to achieve accurate quantification of carbon emissions and emission reduction optimization for the entire phosphogypsum process. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal. Based on the current status of phosphogypsum production and pollution discharge and the shortcomings of the current carbon emission accounting framework, a scientific and systematic phosphogypsum carbon emission evaluation tool is constructed. By decomposing and quantifying carbon emissions in all stages of the entire life cycle of phosphogypsum from raw material production, transportation, harmless treatment, comprehensive utilization to storage, a comprehensive assessment of carbon emissions from different treatment and disposal methods is achieved.

[0006] To achieve the above objectives, the present invention provides a method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal, comprising the following steps:

[0007] S1: Determine the research object and functional unit, and determine the system boundary of carbon footprint within the entire life cycle of phosphogypsum;

[0008] S2: Within the system boundary, the carbon footprint is divided into the raw material production stage, the raw material transportation stage, the phosphogypsum harmless treatment stage, the phosphogypsum comprehensive utilization stage, and the phosphogypsum storage stage;

[0009] S3: Obtain a dataset of the entire life cycle of phosphogypsum utilization and disposal, identify each carbon emission source and its corresponding energy consumption, and determine the corresponding greenhouse gas emission factor (EF). j-k , and the global warming potential (GWP) of each greenhouse gas k EF j-k is the emission factor of greenhouse gas k generated by the consumption of energy j;

[0010] S4: Based on the consumption of raw and auxiliary materials M in the production stage i Quantify the carbon emissions C during the raw material and auxiliary material production stage 生产 ;

[0011] Based on the energy consumption E in the transportation stage of raw materials and auxiliary materials 运输-j Quantify the carbon emissions C during the transportation of raw materials and auxiliary materials 运输 ;

[0012] Based on the energy consumption E in the harmless stage of phosphogypsum 无害化-j Quantify the carbon emissions C during the harmless treatment of phosphogypsum 无害化 ;

[0013] Based on the energy consumption E of the comprehensive utilization stage of phosphogypsum 利用-j Quantify the carbon emissions C during the comprehensive utilization of phosphogypsum 利用 ;

[0014] The carbon emissions C during the phosphogypsum storage stage are calculated based on the amount of leachate produced during the phosphogypsum storage stage. 堆存 ;

[0015] S5: Summarize the total carbon emissions C of the entire life cycle of phosphogypsum utilization and disposal, and calculate it using the following formula:

[0016] C=C 生产 +C 运输 +C 无害化 +C 利用 +C 堆存 .

[0017] Among them, the research objects in S1 include the carbon emission process of phosphogypsum in different utilization and disposal links, and the functional unit is generally determined to be the utilization and disposal of 1 ton of phosphogypsum.

[0018] Furthermore, the dataset includes the types and amounts of materials used, disposal process and time, transportation methods, distance and time, etc. throughout the entire life cycle of phosphogypsum utilization and disposal.

[0019] Furthermore, the system boundary can be defined as the entire life cycle or part of the life cycle of phosphogypsum; the entire life cycle includes raw material acquisition, raw material and auxiliary material transportation, harmless treatment of phosphogypsum, comprehensive utilization of phosphogypsum, and storage and disposal of phosphogypsum;

[0020] The part of the life cycle described is from "cradle to gate", that is, including raw material acquisition, raw and auxiliary material transportation, harmless treatment of phosphogypsum, and comprehensive utilization of phosphogypsum; or a single stage such as phosphogypsum storage and disposal as the system boundary for independent research.

[0021] Furthermore, the carbon emission sources and their carbon emission factors obtained in step S3 include the following:

[0022] The factors in the raw material and auxiliary material production stage include one or more of the following factors: the amount of phosphogypsum processed and its carbon emission factor; the amount of auxiliary materials (such as washing agents and quicklime) used in the harmless treatment of phosphogypsum and its carbon emission factor; the amount of auxiliary materials (such as quicklime, carbide slag, clay, etc.) used in the comprehensive utilization process and its carbon emission factor;

[0023] The factors in the raw material transportation stage include one or more of the following factors: fuel (such as diesel, gasoline) consumption and carbon emission factor during the transportation of raw materials; transportation mode (such as road, water, rail) and transportation distance;

[0024] The factors in the harmless treatment stage of phosphogypsum include one or more of the following factors: energy consumption (such as electricity, coal, natural gas) and carbon emission factors of the harmless treatment process;

[0025] The factors in the comprehensive utilization stage of phosphogypsum include one or more of the following factors: energy consumption (such as electricity, coal, natural gas) and its carbon emission factor in the comprehensive utilization stage;

[0026] The factors in the phosphogypsum storage stage include one or more of the following factors: the amount of phosphogypsum leachate produced and the carbon emission factor of its leachate treatment method (such as closed type, open type).

[0027] Furthermore, the emission sources and carbon emission factors of the phosphogypsum comprehensive utilization stage are determined according to the specific utilization methods, which include:

[0028] For the production of gypsum board: Energy consumption may include one or more of coal, natural gas and electricity;

[0029] Used in the production of cement retarders: Energy consumption may be mainly electricity;

[0030] For sulfuric acid co-production of cement clinker: Energy consumption may include coal and electricity;

[0031] For roadbed materials: Energy consumption may be fuel during construction;

[0032] For filling materials: Energy consumption may be electricity during preparation and transportation;

[0033] For soil conditioners: Energy consumption may be electricity and fuel during production and application.

[0034] The emission sources of specific utilization methods need to be determined in combination with the actual production process and technical path, and the types, quantities and corresponding carbon emission factors of energy consumption must be recorded in detail.

[0035] Furthermore, the types of auxiliary materials used in the raw material production stage will vary depending on the different phosphogypsum harmless treatment technologies and comprehensive utilization methods. The auxiliary materials used in the phosphogypsum harmless treatment stage include the following:

[0036] If water washing is used, industrial water will be used to reduce the soluble phosphorus and fluorine content in the phosphogypsum, and the wastewater from the washing may also need to be treated;

[0037] If the neutralization method is used, lime, carbide slag or other alkaline substances need to be added to neutralize impurities such as phosphorus and fluorine, and the pH value of the slurry needs to be adjusted to 6-9 to reduce the content of harmful impurities;

[0038] If calcination is used, no chemicals are required during the roasting process, but fuel such as coal or natural gas may be required;

[0039] The auxiliary materials in the comprehensive utilization stage of phosphogypsum include the following:

[0040] Used in the production of paper-faced gypsum board: auxiliary materials include face paper, modified corn starch, coagulant, paper fiber, foaming agent, edge adhesive, etc.

[0041] Used to make cement retarder: phosphogypsum and quicklime or carbide slag are required;

[0042] For sulfuric acid co-production of cement clinker: auxiliary materials include phosphogypsum, clay, iron powder and fluorite;

[0043] For roadbed materials: mainly lime and other stabilizers;

[0044] For filling materials: auxiliary materials may include mixed cement and fly ash;

[0045] For soil conditioner: the auxiliary materials can include modifiers or other organic materials.

[0046] The selection and amount of specific auxiliary materials are determined according to the process requirements of harmless treatment and comprehensive utilization mode, and all relevant data should include the type, usage amount and corresponding carbon emission factor of the auxiliary materials.

[0047] Further, in step S3, the greenhouse gases generally include CO2, CH4, N2O and other greenhouse gases.

[0048] Further, in step S4, the carbon emission amount C 生产 of the raw and auxiliary material production stage is calculated as follows:

[0049] C 生产 =∑m i ×CEF i

[0050] In the formula, m i is the mass of raw material or auxiliary material i when processing unit phosphogypsum; CEF i is the carbon emission factor of the i-th raw material or auxiliary material; wherein, the carbon emission factor of the raw material phosphogypsum is different when the processing mode is different, and the specific carbon emission factor is: when the phosphogypsum is finally treated by stacking, it is regarded as solid waste treatment, and the carbon emission factor CEF is 0; when the phosphogypsum is finally used for comprehensive utilization, it is regarded as a raw material for comprehensive utilization, and the carbon emission factor CEF is-1 / 2 of the carbon emission factor of the replaced raw material (such as natural gypsum).

[0051] Further, in step S4, the return transportation coefficient is introduced in the raw and auxiliary material transportation stage, and the j-th energy consumption amount E 运输-j of the material transportation stage is calculated according to the transportation vehicle type, transportation distance and comprehensive oil consumption, and the calculation formula is as follows:

[0052] E 运输-j =∑m i ×D i ×q i-j ×(1+n)

[0053] In the formula, m i is the mass of raw material or auxiliary material i when processing unit phosphogypsum; D j is the transportation distance of raw material or auxiliary material i; q i-j is the energy consumption of raw material or auxiliary material i per km; and n is the return transportation coefficient, which is as follows:

[0054]

[0055] Based on the energy consumption amount E 运输-j of the raw and auxiliary material transportation stage, the carbon emission amount C运输 , the calculation formula is as follows:

[0056] C 运输 =∑∑E 运输-j ×EF j-k ×GWP k

[0057] In the formula, EF j-k is the emission factor of greenhouse gas k generated by the consumption of energy j; GWP k is the global warming potential of greenhouse gas k.

[0058] Further, the calculation formula of the carbon emission C 无害化 of the phosphogypsum harmless stage is as follows:

[0059] C 无害化 =∑∑E 无害化-j ×EF j-k ×GWP k

[0060] In the formula, E 无害化-j is the consumption of energy j when unit phosphogypsum is treated by harmless treatment; EF j-k is the emission factor of greenhouse gas k generated by the consumption of energy j; GWP k is the global warming potential of greenhouse gas k.

[0061] Further, the calculation formula of the carbon emission C 利用 of the phosphogypsum comprehensive utilization stage is as follows:

[0062] C 利用 =∑∑E 利用-j ×EF j-k ×GWP k

[0063] In the formula, E 利用-j is the consumption of energy j when unit phosphogypsum is utilized comprehensively; EF j-k is the emission factor of greenhouse gas k generated by the consumption of energy j; GWP k is the global warming potential of greenhouse gas k.

[0064] Further, the calculation formula of the carbon emission C 堆存 of the phosphogypsum stacking stage is as follows:

[0065] C 堆存 =L×CEF 渗滤液

[0066] In the formula, L is the production amount of leachate in the phosphogypsum stacking stage, which is obtained by simulating different stacking heights by the HELP model (a software model for landfill design, prediction of leachate accumulation and evaluation of leachate seepage to groundwater); CEF渗滤液 The carbon emission factor for leachate treatment is determined based on the specific treatment technology and operating conditions;

[0067] The amount of leachate produced during the phosphogypsum storage stage is further deduced based on the power relationship between the storage height H and the storage volume. The relationship between the storage height and the amount of leachate produced is expressed by the following formula:

[0068]

[0069] Where: p is the density of phosphogypsum, which is 1.7-2.6 tons / cubic meter; M 磷石膏 is the mass of the stockpiled phosphogypsum; H is the height of the phosphogypsum stockpiling; a and b are parameters obtained by data fitting.

[0070] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology:

[0071] 1. The method for determining the lifecycle carbon footprint of phosphogypsum utilization and disposal provided by the present invention is based on the current status of phosphogypsum production and pollution discharge and the deficiencies of the current carbon emission accounting framework. Aiming at the complex carbon emission process of phosphogypsum in different utilization and disposal links, a full lifecycle carbon emission quantification framework covering raw material production, transportation, harmless treatment, comprehensive utilization and storage is constructed to achieve a comprehensive assessment of carbon emissions from different treatment and disposal methods. By establishing a phased carbon emission quantification model, the full lifecycle carbon emission accounting of phosphogypsum is made more scientific and comprehensive, which can fill the gaps and deficiencies in the lifecycle carbon footprint accounting of phosphogypsum utilization and disposal processes.

[0072] 2. The method described in this invention fully considers the differences in carbon emission sources during the different processing and utilization stages of phosphogypsum, constructing a comprehensive carbon emission inventory and improving the accuracy of carbon emission accounting. By systematically decomposing carbon emission sources at each stage, high-carbon emission links and key emission reduction potential can be clearly identified. This provides a scientific basis for enterprises and management departments to optimize resource utilization pathways and strengthen carbon emission reduction management, promoting the transformation of phosphogypsum management towards low-carbon, green development, and contributing to the realization of the national carbon neutrality goal.

[0073] 3. The present invention fully considers the carbon emissions generated by the leachate during the storage stage of phosphogypsum, and simulates different storage heights according to the HELP model to obtain the amount of leachate generated. This method is accurate and convenient, which is conducive to the scientific and reasonable calculation of the carbon emissions during the storage stage, thereby improving the accuracy of carbon emission accounting throughout the life cycle.

[0074] 4. This method is not only applicable to carbon footprint calculation of phosphogypsum, but also has broad applicability, providing a reference for carbon footprint assessment of other industrial byproducts (such as fly ash and slag) or solid waste, thereby promoting the method's widespread application. Through lifecycle carbon footprint calculation, this invention provides practical technical support for ecological and environmental protection, resource conservation, and the promotion of low-carbon economic development, contributing to the realization of the country's "dual carbon" goals. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 It is a structural diagram of the calculation model of the present invention.

[0076] Figure 2 This is the system boundary composition diagram of the present invention.

[0077] Figure 3 This is the system boundary diagram of Example 1 of the present invention.

[0078] Figure 4 This is a fitting diagram of the liquid-to-solid ratio and the stockpile height in the stockpile stage of Example 1 of the present invention. DETAILED DESCRIPTION

[0079] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0080] Example 1

[0081] This embodiment discloses a method and system for determining the lifecycle carbon footprint of phosphogypsum utilization and disposal. A phosphogypsum comprehensive utilization enterprise in Hubei Province was selected as the research object. Based on the material, energy consumption, and other data provided by the enterprise, the carbon emissions caused by processing one ton of phosphogypsum in 2024 were calculated. The method includes the following steps:

[0082] (1) Determine the research object, functional unit and system boundary

[0083] This example establishes the research object as the carbon emission process of phosphogypsum in the utilization and disposal process of a phosphogypsum comprehensive utilization enterprise in Hubei Province, and the functional unit is determined as the utilization and disposal of 1 ton of phosphogypsum by the enterprise. The present invention provides a relatively complete description of the system boundary and life cycle stages. Figure 2 In this embodiment, after all the phosphogypsum of a phosphogypsum comprehensive utilization enterprise in Hubei Province is harmlessly treated, half of it is used for comprehensive utilization and the other half is directly stored. Therefore, the system boundary of this embodiment is defined as the entire process from the production of raw materials to the comprehensive utilization or storage of phosphogypsum. The system boundary of this embodiment is as follows: Figure 3As shown;

[0084] (2) Determine the life cycle stages, which are divided into the raw material production stage, the raw material transportation stage, the phosphogypsum harmless treatment stage, the phosphogypsum comprehensive utilization stage, and the phosphogypsum storage stage. Determine the carbon emission sources for each stage and establish a carbon emission metering inventory, as shown in Table 1.

[0085] Table 1 Carbon emission measurement list

[0086]

[0087] (3) Determine each carbon emission source and the corresponding energy consumption, that is, determine the activity data of the main energy consumption and carbon emission sources, and determine the life cycle inventory. Determine the corresponding greenhouse gas emission factor EF j-k , and the global warming potential (GWP) of each greenhouse gas k , which is calculated by converting the global warming potential of each greenhouse gas into carbon dioxide equivalent. Table 2 shows the global warming potential of major greenhouse gases.

[0088] Table 2 Global warming potential of major gases

[0089]

[0090] (4) Based on the raw material consumption m in the raw material production stage i Quantify the carbon emissions C during the raw material and auxiliary material production stage 生产 ;

[0091] C 生产 =∑m i ×CEF i

[0092] Where m i The mass of raw materials or auxiliary materials i when processing unit phosphogypsum; CEF i is the carbon emission factor of the i-th raw and auxiliary material. The carbon emission factors are different for the raw material phosphogypsum depending on the treatment method. Specifically: when the phosphogypsum is finally stored, it is regarded as solid waste treatment and disposal, and the carbon emission factor CEF is 0; when the phosphogypsum is finally utilized as a resource, it is regarded as a resource utilization raw material, and the carbon emission factor CEF is -1 / 2 of the carbon emission factor of the replaced raw material (such as natural gypsum). The company uses 0.5t of phosphogypsum for comprehensive utilization after harmlessness, and 0.5t of it is stored after harmlessness, so it is treated and calculated separately.

[0093] The carbon emissions during the raw material production stage are shown in Table 3, where CO2e represents CO2 equivalent.

[0094] Table 3 Carbon emissions from raw material production

[0095]

[0096] (5) Based on the energy consumption E during the transportation of raw materials and auxiliary materials 运输-j Quantify the carbon emissions C during the transportation of raw materials and auxiliary materials 运输 Introducing the return transport coefficient, the energy consumption E of the jth material transportation stage is calculated based on the transport model, transport distance, and comprehensive fuel consumption. 运输-j , the calculation formula is as follows:

[0097] E 运输-j =∑m i ×D i ×q i-j ×(1+n)

[0098] Where m i D is the mass of raw material or auxiliary material i when processing unit phosphogypsum; j is the transportation distance of raw material or auxiliary material i; q i-j is the energy consumption of unit mass raw material or auxiliary material i per 1 km transport; n is the return transport coefficient, which is 0 when the transport mode is water or rail, and 0.7 when the transport mode is road;

[0099] Based on the energy consumption E in the transportation stage of raw materials and auxiliary materials 运输-j Quantify the carbon emissions C during the transportation of raw materials and auxiliary materials 运输 , the calculation formula is as follows:

[0100] C 运输 =∑∑E 运输-j ×EF j-k ×GWP k

[0101] Where, EF j-k is the emission factor of greenhouse gas k generated by energy j consumption; GWP k is the global warming potential of the greenhouse gas k.

[0102] Combined with the example in step (4), the carbon emissions of the raw material transportation stage C are calculated 运输 It is 20.35tCO2e.

[0103] (6) Carbon emissions during the harmless treatment of phosphogypsum C 无害化 The calculation formula is as follows:

[0104] C 无害化 =∑∑E 无害化-j ×EF j-k ×GWP k

[0105] Where, E 无害化-j EF is the energy consumption per unit hour of harmless treatment of phosphogypsum; j-kis the emission factor of greenhouse gas k generated by energy j consumption; GWP k is the global warming potential of the greenhouse gas k.

[0106] The Hubei enterprise washed and harmlessly treated 1 ton of phosphogypsum. Combined with the example in step (4), the carbon emissions during the harmless treatment stage were calculated as C 无害化 It is 26.00tCO2e.

[0107] (7) Carbon emissions from the comprehensive utilization of phosphogypsum C 利用 The calculation formula is as follows:

[0108] C 利用 =∑∑E 利用-j ×EF j-k ×GWP k

[0109] Where, E 利用-j EF is the consumption of energy j per unit of phosphogypsum for comprehensive utilization; j-k is the emission factor of greenhouse gas k generated by energy j consumption; GWP k is the global warming potential of the greenhouse gas k.

[0110] The Hubei enterprise used 0.5t of harmless phosphogypsum for comprehensive utilization to produce cement retarder. Combined with the example in step (4), the carbon emissions of the phosphogypsum comprehensive utilization stage were calculated as C 利用 It is 9.35tCO2e.

[0111] (8) Carbon emissions during the phosphogypsum storage stage C 堆存 The calculation formula is as follows:

[0112] C 堆存 =L×CEF 渗滤液

[0113] Where, L is the amount of leachate generated during the phosphogypsum storage stage, which is obtained by simulating different storage heights using the HELP model; CEF 渗滤液 It is the carbon emission factor for leachate treatment, which is determined according to the specific treatment technology and operating conditions.

[0114] The calculation formula for the amount of leachate generated during the phosphogypsum storage stage is as follows:

[0115]

[0116] Where: p is the density of phosphogypsum, which is 1.7-2.6 tons / cubic meter; M 磷石膏 is the mass of the stored phosphogypsum, which is 0.5t; H is the storage height of the phosphogypsum, and the average storage height of the phosphogypsum depot is 3m; a and b are parameters obtained by data fitting.

[0117] By simulating the HELP model of the phosphogypsum reservoir, it was found that the relationship between the storage height and the leachate-phosphogypsum liquid-solid ratio is a power relationship:

[0118] L / S=a×H b

[0119] Where: S is the storage volume of phosphogypsum, that is, M 磷石膏 / p, a 20-year simulation of the phosphogypsum reservoir yields a = 11.256; b = -1.061. Figure 4 shown.

[0120] The company in Hubei Province uses 0.5t of harmless phosphogypsum for storage. Combined with the example in step (4), the carbon emissions during the comprehensive utilization of phosphogypsum are calculated as C 堆存 It is 0.13tCO2e.

[0121] (9) The total carbon emissions C of the entire life cycle of phosphogypsum utilization and disposal are calculated using the following formula:

[0122] C=C 生产 +C 运输 +C 无害化 +C 利用 +C 堆存

[0123] Combining the above examples,

[0124] C=C 生产 +C 运输 +C 无害化 +C 利用 +C 堆存

[0125] =8.36+20.35+26.00+9.35+0.13=64.19tCO2e

[0126] Where C 生产 is the carbon emissions in the raw material production stage, C 运输 is the carbon emission during the transportation of raw materials and auxiliary materials, C 无害化 is the carbon emission in the harmless treatment stage of phosphogypsum, C 利用 is the carbon emission in the comprehensive utilization stage of phosphogypsum, C 堆存 It is the carbon emission during the storage stage of phosphogypsum.

[0127] According to the method and system for determining the lifecycle carbon footprint of phosphogypsum utilization and disposal provided by the present invention, an example calculated the carbon emissions resulting from processing one ton of phosphogypsum by a Hubei-based comprehensive phosphogypsum utilization enterprise in 2024. In this example, assuming that one ton of phosphogypsum was completely rendered harmless, 0.5 ton of the rendered phosphogypsum was used for comprehensive utilization to produce cement retarders, and 0.5 ton was stored, a total of 64.19 tonnes of carbon emissions were generated.

[0128] Example 2

[0129] This example calculates the full life cycle carbon emissions of a phosphogypsum comprehensive utilization enterprise processing 1 ton of phosphogypsum for the production of paper-faced gypsum board in 2023, without stockpiling.

[0130] 1. Carbon emissions during the production of raw materials and auxiliary materials C 生产

[0131] Based on the actual situation of the enterprise and the reference emission factors, the carbon emissions of phosphogypsum and the auxiliary materials required for the production of paper-faced gypsum board (face paper, modified corn starch, coagulant, paper fiber, foaming agent, adhesive, etc.) are calculated. The results are:

[0132] C 生产 =10.25tCO2e

[0133] 2. Carbon emissions during the transportation of raw and auxiliary materials C 运输

[0134] According to the actual distance and mode of transportation of raw materials and auxiliary materials, combined with fuel consumption and emission factors, the carbon emissions during the transportation stage are calculated. The results are:

[0135] C 运输 =18.15tCO2e

[0136] 3. Carbon emissions during the harmless treatment of phosphogypsum C 无害化

[0137] The company uses water washing to render phosphogypsum harmless. Combining the energy consumption (such as electricity) and emission factors of the water washing process, the carbon emissions during the harmless treatment stage are calculated. The results are:

[0138] C 无害化 =25.50tCO2e

[0139] 4. Carbon emissions from comprehensive utilization of phosphogypsum C 利用

[0140] All phosphogypsum is used to produce gypsum board. Based on the calculation formula and the energy consumption (such as coal, electricity, and natural gas) of gypsum board production, combined with the corresponding emission factors, we can get:

[0141] C 利用 =12.80tCO2e

[0142] 5. Carbon emissions during the phosphogypsum storage stage C 堆存

[0143] In this embodiment, there is no phosphogypsum storage, so:

[0144] C 堆存 =0tCO2e

[0145] 6. Total carbon emissions over the entire life cycle C

[0146] The total carbon emissions over the entire life cycle are calculated using the following formula:

[0147] C=C 生产 +C 运输 +C 无害化 +C 利用 +C 堆存

[0148] Substituting the above values:

[0149] C=10.25+18.15+25.50+12.80+0=66.70tCO2e

[0150] Example 3

[0151] This example calculates the lifecycle carbon emissions of a phosphogypsum processing company processing one ton of phosphogypsum for storage in 2024. The transportation distance is unknown, and the harmless treatment method is calcination. Energy consumption data for the calcination method is missing, and this data is addressed using the data completion method.

[0152] 1. Carbon emissions during the production of raw materials and auxiliary materials C 生产

[0153] The carbon emissions from the processing volume of phosphogypsum and the auxiliary materials required for harmless treatment are attributed to the production stage of raw and auxiliary materials. Combined with the reference emission factor, the following is calculated:

[0154] C 生产 =8.50tCO2e

[0155] 2. Carbon emissions during the transportation of raw and auxiliary materials C 运输

[0156] The transportation distance is unknown. Based on the estimated distances between other three phosphorus enterprises and phosphogypsum depots in the region of this example, an average transportation distance of 8 kilometers is assumed. The mode of transportation is road transportation. Combined with the carbon emission factor of diesel fuel, the calculation is as follows:

[0157] C 运输 =0.6tCO2e

[0158] 3. Carbon emissions during the harmless treatment of phosphogypsum C 无害化

[0159] The harmless treatment adopts the calcination method. Due to the lack of specific energy consumption data, the typical energy consumption value of the calcination process in the reference is referenced. It is assumed that calcining 1 ton of phosphogypsum requires 50kWh of electricity and 80kg of coal. Combining the emission factors of electricity and coal, the calculation is as follows:

[0160] C 无害化=18.70tCO2e

[0161] 4. Carbon emissions from comprehensive utilization of phosphogypsum C 利用

[0162] In this embodiment, there is no comprehensive utilization of phosphogen gypsum, so:

[0163] C 利用 =0tCO2e

[0164] 5. Carbon emissions during the phosphogypsum storage stage C 堆存

[0165] C 堆存 =L×CEF 渗滤液

[0166] Where, L is the amount of leachate generated during the phosphogypsum storage stage, which is obtained by simulating different storage heights using the HELP model; CEF 渗滤液 is the carbon emission factor for leachate treatment. The specific value is unknown and is replaced by the carbon emission factor of leachate from a similar process, which is 0.173tCO2e per ton.

[0167] The calculation formula for the amount of leachate generated during the phosphogypsum storage stage is as follows:

[0168]

[0169] Where: p is the density of phosphogypsum, which is 1.7-2.6 tons / cubic meter; M 磷石膏 is the mass of the stored phosphogypsum, which is 1 t; H is the phosphogypsum storage height, which is 2 m, using the average storage height of other storage facilities in the area; a and b are parameters obtained by data fitting, using simulated values ​​from other storage facilities, i.e., a = 11.256, b = -1.061.

[0170] Calculate the carbon emissions C during the comprehensive utilization of phosphogypsum 堆存 It is 2.34tCO2e.

[0171] 6. Total carbon emissions over the entire life cycle C

[0172] The total carbon emissions over the entire life cycle are calculated using the following formula:

[0173] C=C 生产 +C 运输 +C 无害化 +C 利用 +C 堆存

[0174] Substituting the above values:

[0175] C=8.50+0.60+18.70+0+2.34=30.14tCO2e

[0176] In summary, according to a method and system for determining the life cycle carbon footprint of phosphogypsum utilization and disposal provided by the present invention, this embodiment calculates that the total life cycle carbon emissions of all stored 1 ton of phosphogypsum after harmless treatment is 30.14 tCO2e.

[0177] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal, characterized in that: The following steps are involved: S1: Determine the carbon emission process and disposal volume of phosphogypsum in different utilization and disposal links, and determine the system boundary of the carbon footprint throughout the life cycle of phosphogypsum; S2: Within the system boundary, the carbon footprint is divided into the raw material production stage, the raw material transportation stage, the phosphogypsum harmless treatment stage, the phosphogypsum comprehensive utilization stage, and the phosphogypsum storage stage; S3: Obtain a dataset of the entire life cycle of phosphogypsum utilization and disposal, and determine the carbon emission sources and corresponding energy consumption at each stage; S4: Obtain the carbon emissions C during the raw and auxiliary material production stage based on the raw and auxiliary material consumption during the raw and auxiliary material production stage. 生产 ; The carbon emissions C of the raw and auxiliary materials transportation stage are obtained based on the energy consumption of the raw and auxiliary materials transportation stage. 运输 ; The carbon emissions C of the phosphogypsum harmless treatment stage are obtained based on the energy consumption of the phosphogypsum harmless treatment stage. 无害化 ; The carbon emissions C during the comprehensive utilization of phosphogypsum are obtained based on the energy consumption during the comprehensive utilization of phosphogypsum. 利用 ; The carbon emissions C during the phosphogypsum storage stage are calculated based on the amount of leachate produced during the phosphogypsum storage stage. 堆存 ; S5: Summarize the total carbon emissions C of the entire life cycle of phosphogypsum utilization and disposal, and calculate it using the following formula: C=C 生产 +C 运输 +C 无害化 +C 利用 +C 堆存 。 2. The method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal according to claim 1, characterized in that: The carbon emission sources and their carbon emission factors obtained in step S3 include the following: The factors in the raw material and auxiliary material production stage include the processing volume of phosphogypsum and its carbon emission factor, the usage volume of auxiliary materials in the harmless treatment of phosphogypsum and its carbon emission factor, and the usage volume of auxiliary materials in the comprehensive utilization process and its carbon emission factor; The factors in the raw material transportation stage include the fuel consumption and carbon emission factor, transportation mode and transportation distance during the transportation of raw materials; The factors of the harmless treatment stage of phosphogypsum include the energy consumption and carbon emission factors of the harmless treatment process; The factors of the comprehensive utilization stage of phosphogypsum include energy consumption and carbon emission factors in the comprehensive utilization stage; The factors in the phosphogypsum storage stage include the amount of phosphogypsum leachate produced and the carbon emission factor of its leachate treatment method.

3. The method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal according to claim 2, characterized in that: The emission sources and carbon emission factors of the comprehensive utilization stage of phosphogypsum are determined according to the specific utilization methods, which include: When used to produce gypsum board, the energy consumption includes one or more of coal, natural gas and electricity; When used to make cement retarders, the energy consumed is mainly electricity; When sulfuric acid is used to co-produce cement clinker, energy consumption mainly includes coal and electricity; When used for roadbed materials, energy consumption mainly consists of fuel used during construction; When used for filling materials, the energy consumption is mainly electricity during preparation and transportation; When used as soil conditioners, energy consumption mainly comes from electricity and fuel during production and application.

4. The method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal according to claim 2, characterized in that: The auxiliary materials for the harmless treatment of phosphogypsum include: When the water washing method is used, industrial water is required to reduce the soluble phosphorus and fluorine content in the phosphogypsum and to treat the water washing wastewater; When using the neutralization method, lime, carbide slag or other alkaline substances need to be added to neutralize phosphorus and fluorine impurities, and the pH value of the slurry should be adjusted to 6-9 to reduce the content of harmful impurities; Using the calcination method, coal or natural gas is required during the roasting process.

5. The method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal according to claim 2, characterized in that: The auxiliary materials in the comprehensive utilization stage of phosphogypsum include: When used in the production of paper-faced gypsum board, the auxiliary materials include face paper, modified corn starch, coagulant, paper fiber, foaming agent, and edge adhesive; When used to make cement retarder, auxiliary materials include phosphogypsum, quicklime and carbide slag; When used for the co-production of cement clinker with sulfuric acid, auxiliary materials include phosphogypsum, clay, iron powder and fluorite; When used as roadbed material, auxiliary materials include lime and stabilizers; When used as filling material, auxiliary materials include mixed cement and fly ash; When used in soil conditioners, auxiliary materials include modifiers.

6. The method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal according to claim 1, characterized in that: In step S4, the carbon emissions during the raw material production stage C 生产 The calculation formula is as follows: C 生产 =∑m i ×CEF i Where m i CEE is the mass of raw materials or auxiliary materials i when processing unit phosphogypsum; i is the carbon emission factor of the i-th raw material or auxiliary material; Among them, the carbon emission factors of the raw material phosphogypsum are different depending on the treatment method. Specifically: when the phosphogypsum is finally stored, it is regarded as solid waste treatment and disposal, and the carbon emission factor CEF is 0; when the phosphogypsum is finally used for comprehensive utilization, it is regarded as a comprehensive utilization raw material, and the carbon emission factor CEF is -1 / 2 of the carbon emission factor of the replaced raw material.

7. The method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal according to claim 1, characterized in that: In step S4, the return transport coefficient is introduced in the raw material transportation stage, and the j-th energy consumption E of the material transportation stage is calculated based on the transportation vehicle type, transportation distance, and comprehensive fuel consumption. 运输-j , the calculation formula is as follows: AND 运输-j =Σm i ×D i ×q i-j ×(1+n) Where m i D is the mass of raw material or auxiliary material i when processing unit phosphogypsum; i is the transportation distance of raw material or auxiliary material i; q i-j is the energy consumption per unit mass of raw material or auxiliary material i per 1 km; n is the return transport coefficient, and its value is as follows: Based on the energy consumption E in the transportation stage of raw materials and auxiliary materials 运输-j Quantify the carbon emissions C during the transportation of raw materials and auxiliary materials 运输 , the calculation formula is as follows: C 运输 =∑∑E 运输-j ×EF j-k ×GWP k Where, EF j-k is the emission factor of greenhouse gas k generated by energy j consumption; GWP k is the global warming potential of the greenhouse gas k.

8. The method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal according to claim 1, characterized in that: The carbon emissions during the harmless treatment of phosphogypsum are C 无害化 The calculation formula is as follows: C 无害化 =∑∑E 无害化-h ×EF j-k ×GWP k Where, E 无害化-j EF is the energy consumption per unit hour of harmless treatment of phosphogypsum; j-k is the emission factor of greenhouse gas k generated by energy j consumption; GWP k is the global warming potential of the greenhouse gas k.

9. The method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal according to claim 1, characterized in that: The carbon emissions from the comprehensive utilization of phosphogypsum are C 利用 The calculation formula is as follows: C 利用 =∑∑E 利用-j ×EF j-k ×GWP k Where, E 利用-j EF is the consumption of energy j per unit of phosphogypsum for comprehensive utilization; j-k is the emission factor of greenhouse gas k generated by energy j consumption; GWP k is the global warming potential of the greenhouse gas k.

10. The method for determining the life cycle carbon footprint of phosphogypsum utilization and disposal according to claim 1, characterized in that: The carbon emissions during the phosphogypsum storage stage are C 堆存 The calculation formula is as follows: C 堆存 =L×CEF 渗滤液 Where, L is the amount of leachate generated during the phosphogypsum storage stage, which is obtained by simulating different storage heights using the HELP model; CEF 渗滤液 The carbon emission factor for leachate treatment is determined based on the specific treatment technology and operating conditions; The amount of leachate produced during the phosphogypsum storage stage is further deduced based on the power relationship between the storage height H and the storage volume. The relationship between the storage height and the amount of leachate produced is expressed by the following formula: Where: p is the density of phosphogypsum, which is 1.7-2.6 tons / cubic meter; M 磷石膏 is the mass of the stockpiled phosphogypsum; H is the height of the phosphogypsum stockpiling; a and b are parameters obtained by data fitting.

Images