Research of the life cycle for two most common routes of steel production with a focus on the impact to the human body

Figures & data

Figure 1. The schematic representation of the steel production process in an oxygen converter and an electric arc furnace with delineated boundaries of the investigated system.

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The figure shows the main stages of steel production in oxygen converters: iron ore mining, coke production, pig iron production in a blast furnace and purging of pig iron in an oxygen converter; and electric arc furnace steel production, which requires collection of steel scrap and its melting in an electric arc furnace.

Figure 2. Process scheme for the production of low-alloy steel in an oxygen converter, created in the software LCA for experts.

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The diagram illustrates a scheme incorporating all input materials required for steel production in an oxygen converter. It also presents the output products, including waste and by-products obtained in the process.

Figure 3. Process scheme for the production of low-alloy steel in an electric arc furnace, created in the software LCA for experts.

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The diagram illustrates a scheme that encompasses all input materials necessary for steel production in an electric arc furnace. It also presents the products obtained at the output, including waste and by-products.

Table 1. Тhe impact on the human body by producing 1 kg of low-alloy steel in BOF and EAF.

Environmental Footprint 3.0	BOF	EAF
Acidification [Mole of H+ eq.]	9.86E–03	1.82E–03
Climate Change – total [kg CO2 eq.]	2.29E+00	4.45E–01
Climate Change, biogenic [kg CO2 eq.]	1.67E–03	2.34E–03
Climate Change, fossil [kg CO2 eq.]	2.29E+00	4.42E–01
Climate Change, land use and land use change [kg CO2 eq.]	1.53E–03	1.06E–04
Ecotoxicity, freshwater – total [CTUe]	6.52E+01	2.88E+00
Ecotoxicity, freshwater inorganics [CTUe]	1.23E+01	1.14E+00
Ecotoxicity, freshwater metals [CTUe]	5.24E+01	1.71E+00
Ecotoxicity, freshwater organics [CTUe]	4.84E–01	2.81E–02
Eutrophication, freshwater [kg P eq.]	6.52E–04	8.18E–06
Eutrophication, marine [kg N eq.]	1.83E–03	2.81E–04
Eutrophication, terrestrial [Mole of N eq.]	1.99E–02	3.07E–03
Human toxicity, cancer – total [CTUh]	1.36E–08	4.99E–10
Human toxicity, cancer inorganics [CTUh]	2.53E–20	1.29E–20
Human toxicity, cancer metals [CTUh]	5.76E–09	3.93E–10
Human toxicity, cancer organics [CTUh]	7.84E–09	1.06E–10
Human toxicity, non-cancer – total [CTUh]	4.27E–08	5.22E–09
Human toxicity, non-cancer inorganics [CTUh]	2.90E–08	1.55E–09
Human toxicity, non-cancer metals [CTUh]	1.27E–08	3.66E–09
Human toxicity, non-cancer organics [CTUh]	1.30E–09	4.35E–11
Ionising radiation, human health [kBq U235 eq.]	5.26E–02	5.01E–02
Land Use [Pt]	4.90E+00	2.39E+00
Ozone depletion [kg CFC-11 eq.]	6.60E–08	2.89E–09
Particulate matter [Disease incidences]	1.46E–07	1.59E–08
Photochemical ozone formation, human health [kg NMVOC eq.]	9.27E–03	8.45E–04
Resource use, fossils [MJ]	3.00E+01	5.98E+00
Resource use, mineral and metals [kg Sb eq.]	2.75E–05	4.60E–07
Water use [m^3 world equiv.]	7.16E–01	2.94E–02

Figure 4. Comparison of the impact of the investigated processes on the human body.

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The results of the comparative analysis are presented for 1 kg of low-alloy steel. The diagram shows that higher values of the impact of hazardous substances are characteristic of steel production in BOF. This conclusion is evident in each of the selected categories.

Figure 5. The distribution of the impact on the human body by the process of producing 1 kg of steel in oxygen converters is presented in each of the researched impact categories.

(a) The category of Human toxicity, cancer – total [CTUh]. The production of cast iron and additives such as ferromanganese and ferronickel plays a key role in this category.

(b) The category of Human toxicity, cancer inorganics [CTUh]. Oxygen and additives such as ferronickel play a key role in this category.

(c) The category of Human toxicity, cancer metals [CTUh]. Alloying additives such as ferromanganese and ferronickel play a key role in this category.

(d) The category of Human toxicity, cancer organics [CTUh]. All negative impact in this category is attributed to the process of cast iron production.

(e) The category of Human toxicity, non-cancer – total [CTUh]. The majority of harmful impact in this category is caused by cast iron production, but in addition, ferronickel and refractories exert a noticeable influence.

(f) The category of Human toxicity, non-cancer inorganics [CTUh]. The main portion of hazardous emissions is caused by the process of cast iron production.

(g) The category of Human toxicity, non-cancer metals [CTUh]. Half of the hazardous impact in this category is caused by the steel production process, while the other portion is attributed to refractories and alloying additives.

(h) The category of Human toxicity, non-cancer organics [CTUh]. The majority of the harmful impact in this category is caused by molybdenite, while another portion is attributed to cast iron production.

(i) The category of Ionizing radiation, human health [kBq U₂₃₅ eq.]. Half of the harmful impact in this category is caused by the process of cast iron production. Additionally, noticeable influence here is attributed to oxygen and alloying additives.

(j) Category Particulate matter [Disease incidences]. In this category, more than half of the hazardous impact is caused by the cast iron production process.

(k) Category Photochemical ozone formation, human health [kg NMVOC eq.]. In this category, the main portion of the hazardous impact is caused by the cast iron production process. Additionally, alloying additives have a noticeable influence on this category.

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This figure shows which of the processes in the production of steel in oxygen converters has the most toxic impact on the human body in each of the impact categories studied. According to the results, the process of iron production in a blast furnace has the most toxic impact in each of the impact categories studied.

Figure 5. (Continued).

Figure 6. The distribution of the impact on the human body by the process of producing 1 kg of steel in an electric arc furnace is presented in each of the impact categories.

(a) The category of Human toxicity, cancer - total [CTUh]. The highest impact in this category is caused by dust from electric arc furnaces.

(b) The category of Human toxicity, cancer inorganics [CTUh]. Most of the hazardous effects are due to oxygen.

(c) The category of Human toxicity, cancer metals [CTUh]. In this category, the main exposure is to electric arc dust.

(d) The category of Human toxicity, cancer organics [CTUh]. In this category, the hazardous impact is caused by quicklime and the electricity required for this process.

(e) The category of Human toxicity, non-cancer - total [CTUh]. In this category, electricity and arc dust have a significant impact.

(f) The category of Human toxicity, non-cancer inorganics [CTUh]. More than half of the hazardous impacts are caused by the electricity used.

(g) The category of Human toxicity, non-cancer metals [CTUh]. In this category, the hazardous effects are attributed to arc furnace dust, electrical energy, and refractories.

(h) The category of Human toxicity, non-cancer organics [CTUh]. The largest impact in this category is from the electricity used to run the process.

(i) The category of Ionizing radiation, human health [kBq U235 eq.]. The main impact in this category is caused by electricity.

(j) Category Particulate matter [Disease incidences]. This category is mainly influenced by electricity and alloying additives.

(k) Category Photochemical ozone formation, human health [kg NMVOC eq.]. In this category, the hazardous impact is caused by the electricity used and ferromanganese.

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This figure shows which of the processes in the production of steel in electric arc furnaces has the most toxic impact on the human body in each of the impact categories studied. According to the results, the most toxic impact is the process of generating the electricity required for the process and electric arc dust.

Figure 6. (Continued).

Figure 7. Impact on the human organism of the steel production process in an electric arc furnace using various types of electrical energy.

(a) The category of Human toxicity, cancer – total [CTUh]. In this category, the scenario involving the use of electrical energy generated from wind power will have the highest negative impact, while the safest option will be the use of electrical energy from nuclear power.

(b) The category of Human toxicity, cancer inorganics [CTUh]. In order to minimize the hazardous impact in this category, it is necessary to use electrical energy from hydroelectric power.

(c) The category of Human toxicity, cancer metals [CTUh]. In this case, the use of electrical energy generated from natural gas will have the highest hazardous impact.

(d) The category of Human toxicity, cancer organics [CTUh]. The lowest level of toxic organic substances causing cancer that we can achieve for the investigated process is by using electrical energy from nuclear power. The most hazardous option in this case is the use of electrical energy from biogas.

(e) The category of Human toxicity, non-cancer – total [CTUh]. In this category, the most hazardous is the use of electrical energy obtained from natural gas.

(f) The category of Human toxicity, non-cancer inorganics [CTUh]. In this case, the highest level of danger is associated with the use of electrical energy generated from biogas. The safest option is hydroelectric power usage.

(g) The category of Human toxicity, non-cancer metals [CTUh]. The highest level of danger is posed by the use of electrical energy generated from natural gas.

(h) The category of Human toxicity, non-cancer organics [CTUh]. In this category, the safest option is the use of electrical energy from hydroelectric power.

(i) The category of Ionizing radiation, human health [kBq U₂₃₅ eq.]. The use of electrical energy from nuclear power provokes the highest level of ionizing radiation emissions.

(j) Category Particulate matter [Disease incidences]. The use of electrical energy from biogas will have the highest emissions level in this category for the investigated process.

(k) Category Photochemical ozone formation, human health [kg NMVOC eq.]. For the investigated process in this category, the use of electrical energy from biogas yields the highest hazardous outcome.

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The figure illustrates a comparison of the usage of 8 types of electrical energy from various sources in each of the investigated categories.

Figure 7. (Continued).

Table 2. Uncertainty analysis of investigated processes.

Uncertainty	Description	Estimated рercentage of uncertainty impact
Input Data Uncertainty	The data sources regarding material expenses, energy consumption, and emissions were obtained by averaging data from the Sphera, EcoInvent databases, and the BAT reference document for iron and steel production.	5–20%
Process Variability	The research results depend on the operating conditions, equipment productivity, or characteristics of the input raw materials. Factors such as fluctuations in electricity supply, changes in scrap composition, oxygen injection rate, temperature, and mixing intensity are considered.	10–30%
Model Assumptions	The obtained results heavily depend on the assumptions made during the process modeling. In our case, these include: Slag resulting from the process is sent for vitrification. Inert waste is completely disposed of in the inert material landfill. Scrap metal arrives at the plant already sorted. For electricity, natural gas, and coke, the decision was made to use a grid mix that is current for Europe in the models.	5–15%
Parameter Uncertainty	The LCA model for steel production depends on parameters such as conversion factors, emission factors, and environmental impact characterization factors. These parameters may be associated with uncertainty due to variability in measurement techniques, data quality, and applicability to specific contexts.	10–25%
Temporal Uncertainty	The uncertainty in this case relates to fluctuations in emissions and their environmental impact over time, including changes in energy sources, technological progress, and market dynamics.	5–15%

Table 3. Sensitivity Analysis of Variables for the studied steel production processes.

Variable	EAF	BOF
Steel scrap	Scrap metal is the main raw material in this process. Behind it lies the final quality, price, and environmental impact of the produced product. The chemical composition of the scrap metal is crucial, as it determines the amount of alloying elements and additives used in the future and, consequently, their impact on the environment and human health. The source and cleanliness of the scrap metal are also of great importance, as they affect the efficiency of melting and slag formation. Proper management of the quality and composition of scrap metal is crucial in this case.	Scrap constitutes an average of 25–35% by weight in relation to the weight of molten iron. Clean, high-quality scrap requires less energy for melting and purification, resulting in lower overall energy consumption.
Iron ore	Iron ore is typically used in small quantities as an additional source of iron to supplement the primary raw material. By using iron ore in this case, it is also possible to regulate the chemical composition of the future product, leading to reduced use of impurities or alloying elements.	Iron ore is the primary raw material. The energy efficiency of the investigated process and its environmental impact depend on its chemical composition, particle size, and iron content. The characteristics of iron ore strongly influence the price of the final product, leading to further consequences.
Electricity	Electricity is the primary source of energy. It is necessary for creating an electric arc between graphite electrodes, which is required for melting scrap metal. Its source and characteristics are critically important. Stable voltage levels, frequency, and waveform are essential conditions for maintaining stable arc conditions and achieving uniform heating of the scrap metal. All of the above directly impact the energy efficiency of the process, its environmental impact, and the final product price.	Energy plays a secondary role, mainly associated with auxiliary processes such as oxygen production, furnace operation, and powering control systems.
Natural gas	Natural gas plays a secondary role for auxiliary processes or as a backup energy source.	Natural gas serves as the primary fuel to provide the necessary heat for the oxygen blowing process and to maintain the desired temperature and chemical composition in the converter vessel. Its quality and composition are important factors influencing the efficiency, safety, and environmental impact of the process. The quality of natural gas directly affects its calorific value, combustion efficiency, and heat transfer characteristics, which in turn affect heating productivity and energy consumption in the converter furnace. Also crucial is the cleanliness of natural gas, as impurities or additives in natural gas, such as hydrogen sulfide (H2S), carbon monoxide (CO), and moisture, can pose safety hazards, corrode equipment, and affect process reliability.
Additives	For EAF, where scrap metal is the primary raw material, controlling and adding impurities and alloying elements play a crucial role in achieving the desired chemical composition and properties of steel. The ability to adjust the composition in real-time provides greater flexibility and customization, making it particularly important for producing specialty steel and meeting stringent customer requirements. Alloying elements such as manganese (Mn), chromium (Cr), nickel (Ni), and molybdenum (Mo) significantly impact the quality of steel, but at the same time, their production and use processes have serious environmental consequences. Proper selection and control of impurities and alloying materials help optimize metallurgical processes such as deoxidation, desulfurization, and degassing.	In this case, the primary steel refining process is oxygen blowing. Although alloying elements are still important for regulating the chemical composition of steel in basic oxygen converters, the focus may shift towards controlling impurities and achieving efficient processing processes.
Waste management (slag)	Waste management, including slag processing and utilization, is of paramount importance in each of the studied processes. DSP slag may contain heavy metals and other pollutants that require careful handling. Sending slag to landfills can lead to environmental pollution and ecosystem degradation due to potential leaching of heavy metals and harmful chemicals into the soil and groundwater. Vitrification involves melting slag at high temperatures to form a glass-like material, reducing the leaching of pollutants and making it suitable for safe disposal or reuse. Skimming improves slag management, reducing environmental risks and promoting safe disposal of slag waste. However, energy consumption and greenhouse gas emissions associated with the process should be considered for an overall assessment of sustainability. Additionally, slag fillers can be used as substitutes for natural fillers in road construction, sidewalks, embankments, and concrete production.	Effective waste management practices are crucial for minimizing the environmental impact of slag disposal, preventing soil and water contamination, and protecting ecosystems and human health. Slag from converter converters contains high concentrations of iron oxides, making it suitable for secondary processing in steel production processes as a flux or raw material. Decisions regarding waste management are among the most important in this situation.

Data availability statement

The data that support the findings of this study are available from the corresponding author, I. Harasymchuk, upon reasonable request.