At the intersection of the“dual carbon”goal and the era of digital intelligence(DI),exploring the synergy between pollution and carbon reduction(SPCR)within the context of DI is important for promoting a comprehensi...At the intersection of the“dual carbon”goal and the era of digital intelligence(DI),exploring the synergy between pollution and carbon reduction(SPCR)within the context of DI is important for promoting a comprehensive green transformation of economic and social development.This study,based on urban panel data from 281 prefecture-level cities in China' Mainland from 2010 to 2020,developed a DI indicator system for these cities and employed a double machine learning algorithm for the first time to investigate the intrinsic mechanisms and incentivizing effects of DI on SPCR.The results showed that:①DI significantly promotes SPCR.②Mechanism tests demonstrated that DI can indirectly enhance SPCR by optimizing resource allocation and reinforcing government interventions.③Further analysis showed that the impact of DI on SPCR was more substantial in regions with lower levels of economic and environmental competition.Moreover,the SPCR driven by DI exhibited heterogeneity,characterized by stronger effects in“resource-based cities>non resource-based cities”and“non-capital economic zones>capital economic zones”.The conclusions of this study hold significant implications for fully harnessing the synergy between digitization and intelligence to empower SPCR.In addition,the findings are valuable for the government’s integrated promotion of the“dual carbon”goal and the“digital China”strategy.展开更多
Embedding direct reduction followed by magnetic separation was conducted to fully recover iron and titanium separately from beach titanomagnetite （TTM）. The influences of reduction conditions, such as molar ratio of...Embedding direct reduction followed by magnetic separation was conducted to fully recover iron and titanium separately from beach titanomagnetite （TTM）. The influences of reduction conditions, such as molar ratio of C to Fe, reduction time, and reduction temperature, were studied. The results showed that the TTM concentrate was reduced to iron and iron-titanium oxides, depending on the reduction time, and the reduction sequence at 1 200℃ was suggested as follows ： Fe2.75 Ti0.25O4→Fe2TiO4→FeTiO3→FeTi2O5. The reduction temperature played a considerable role in the reduction of TTM concentrates. Increasing temperature from 1 100 to 1 200℃ was beneficial to recovering titanium and iron, whereas the results deteriorated as temperature increased further. The results of X-ray diffraction and scanning electron microscopy analyses showed that low temperature （≤1100℃） was unfavorable for the gasification of reductant, resulting in insufficient reducing atmosphere in the reduction process. The molten phase was formed at high temperatures of 1250-1 300℃, which accelerated the migration rate of metallic particles and suppressed the diffusion of reduction gas, resulting in poor reduction. The optimum conditions for reducing TTM concentrate are as follows： molar ratio of C to Fe of 1.68, reduction time of 150 min, and reduction temperature of 1 200℃. Under these conditions, direct reduction iron powder, assaying 90.28 mass% TFe and 1.73 mass% TiO2 with iron recovery of 90.85%, and titanium concentrate, assaying 46.24 mass% TiO2 with TiO2 recovery of 91.15%, were obtained.展开更多
The reduction kinetics of hematite in the presence of coke as a reductant was studied via isothermal and non-isothermal thermodynamic analyses. The isothermal reduction of hematite was conducted at a pre-determined te...The reduction kinetics of hematite in the presence of coke as a reductant was studied via isothermal and non-isothermal thermodynamic analyses. The isothermal reduction of hematite was conducted at a pre-determined temperature ranging from 1423 to 1573 K. The results indicated that a higher reduction temperature led to an increased reduction degree and an increased reduction rate. The non-isothermal reduction of hematite was carried out from room temperature to 1573 K at various heating rates from 5 to 15 K·min^（-1）. A greater heating rate gave a greater reduction rate but decreased reduction degree. With an increase in temperature, both the reduction rate and the reduction degree increased at a smaller rate when the temperature was less than 1150 K, and they increased at a higher rate when the temperature was greater than 1150 K before completion of the reduction reaction. Both the isothermal and the non-isothermal reduction behaviors of hematite were described by the Avrami–Erofeev model. For the isothermal reduction, the apparent activation energy and pre-exponential factor were 171.25 kJ ·mol^（-1） and 1.80 × 10~5 min^（-1）, respectively. In the case of non-isothermal reduction, however, the apparent activation energy and pre-exponential factor were correlated with the heating rate.展开更多
基金funded by the General Program of the National Natural Science Foundation of China [Grant No.72473059]the Ministry of Education Humanities and Social Science Planning Fund Project [Grant No.23YJA790026]+1 种基金the Yunnan Province Basic Research Program General Project [Grant No.202401AT070393]the Innovation and Development Research Think Tank for Resource based Industries at Kunming University of Technology [Grant No.XXZK20-23006].
文摘At the intersection of the“dual carbon”goal and the era of digital intelligence(DI),exploring the synergy between pollution and carbon reduction(SPCR)within the context of DI is important for promoting a comprehensive green transformation of economic and social development.This study,based on urban panel data from 281 prefecture-level cities in China' Mainland from 2010 to 2020,developed a DI indicator system for these cities and employed a double machine learning algorithm for the first time to investigate the intrinsic mechanisms and incentivizing effects of DI on SPCR.The results showed that:①DI significantly promotes SPCR.②Mechanism tests demonstrated that DI can indirectly enhance SPCR by optimizing resource allocation and reinforcing government interventions.③Further analysis showed that the impact of DI on SPCR was more substantial in regions with lower levels of economic and environmental competition.Moreover,the SPCR driven by DI exhibited heterogeneity,characterized by stronger effects in“resource-based cities>non resource-based cities”and“non-capital economic zones>capital economic zones”.The conclusions of this study hold significant implications for fully harnessing the synergy between digitization and intelligence to empower SPCR.In addition,the findings are valuable for the government’s integrated promotion of the“dual carbon”goal and the“digital China”strategy.
基金financially supported by the National Natural Science Foundation of China (Grant No.51474018)
文摘Embedding direct reduction followed by magnetic separation was conducted to fully recover iron and titanium separately from beach titanomagnetite （TTM）. The influences of reduction conditions, such as molar ratio of C to Fe, reduction time, and reduction temperature, were studied. The results showed that the TTM concentrate was reduced to iron and iron-titanium oxides, depending on the reduction time, and the reduction sequence at 1 200℃ was suggested as follows ： Fe2.75 Ti0.25O4→Fe2TiO4→FeTiO3→FeTi2O5. The reduction temperature played a considerable role in the reduction of TTM concentrates. Increasing temperature from 1 100 to 1 200℃ was beneficial to recovering titanium and iron, whereas the results deteriorated as temperature increased further. The results of X-ray diffraction and scanning electron microscopy analyses showed that low temperature （≤1100℃） was unfavorable for the gasification of reductant, resulting in insufficient reducing atmosphere in the reduction process. The molten phase was formed at high temperatures of 1250-1 300℃, which accelerated the migration rate of metallic particles and suppressed the diffusion of reduction gas, resulting in poor reduction. The optimum conditions for reducing TTM concentrate are as follows： molar ratio of C to Fe of 1.68, reduction time of 150 min, and reduction temperature of 1 200℃. Under these conditions, direct reduction iron powder, assaying 90.28 mass% TFe and 1.73 mass% TiO2 with iron recovery of 90.85%, and titanium concentrate, assaying 46.24 mass% TiO2 with TiO2 recovery of 91.15%, were obtained.
基金financially supported by the National Natural Science Foundation of China (No.51134002)the Fundamental Research Funds for the Central Universities of China (No.N140106001)
文摘The reduction kinetics of hematite in the presence of coke as a reductant was studied via isothermal and non-isothermal thermodynamic analyses. The isothermal reduction of hematite was conducted at a pre-determined temperature ranging from 1423 to 1573 K. The results indicated that a higher reduction temperature led to an increased reduction degree and an increased reduction rate. The non-isothermal reduction of hematite was carried out from room temperature to 1573 K at various heating rates from 5 to 15 K·min^（-1）. A greater heating rate gave a greater reduction rate but decreased reduction degree. With an increase in temperature, both the reduction rate and the reduction degree increased at a smaller rate when the temperature was less than 1150 K, and they increased at a higher rate when the temperature was greater than 1150 K before completion of the reduction reaction. Both the isothermal and the non-isothermal reduction behaviors of hematite were described by the Avrami–Erofeev model. For the isothermal reduction, the apparent activation energy and pre-exponential factor were 171.25 kJ ·mol^（-1） and 1.80 × 10~5 min^（-1）, respectively. In the case of non-isothermal reduction, however, the apparent activation energy and pre-exponential factor were correlated with the heating rate.
