As part of efforts to reduce anthropogenic CO_(2) emissions by the steelmaking industry,this study investigated the direct reduction of industrially produced hematite pellets with H_(2) using the Doehlert experimental...As part of efforts to reduce anthropogenic CO_(2) emissions by the steelmaking industry,this study investigated the direct reduction of industrially produced hematite pellets with H_(2) using the Doehlert experimental design to evaluate the effect of pellet diameter(10.5-16.5 mm),porosity(0.36-0.44),and temperature(600-1200℃).A strong interactive effect between temperature and pellet size was observed,indicating that these variables cannot be considered independently.The increase in temperature and decrease in pellet size considerably favor the reduction rate,while porosity did not show a relevant effect.The change in pellet size during the reduction was negligible,except at elevated temperatures due to crack formation.A considerable decrease in mechanical strength at high temperatures suggests a maximum process operating temperature of 900℃.Good predictive capacity was achieved using the modified grain model to simulate the three consecutive non-catalytic gas-solid reactions,considering different pellet sizes and porosities,changes during the reaction from 800 to 900℃.However,for other temperatures,different mechanisms of structural modifications must be considered in the modeling.These results represent significant contributions to the development of ore pellets for CO_(2)-free steelmaking technology.展开更多
A comparative study of the number of taxa and fungal biomass consumed by the Pygmies and the Bantus of Gabon has been realized in two Gabon north regions (Ogooue-Ivindo and the Woleu-Ntem). This study has allowed not ...A comparative study of the number of taxa and fungal biomass consumed by the Pygmies and the Bantus of Gabon has been realized in two Gabon north regions (Ogooue-Ivindo and the Woleu-Ntem). This study has allowed not only to establish the list of consumed fungal sorts by those populations, but also to estimate the daily consumed fungal biomasses by each ethnical group. The study has revealed a significant difference between a numbers of taxa and the quantity of mushrooms consumed by various ethnical groups: the Pygmies of the area who live especially by hunting and fishing consumed 96% of the recorded taxa with some high mushrooms quantities (around 3 kg/day/family);the Bantus who live nearby Pygmies also consumed some high mushrooms quantities (around 2 kg/day/family) but a low taxa number (56% of taxa counted by the Fang;69% by the Kota;39% by the Kwele);on the other hand, the Bantus living nearest the Pygmies consumed a high taxa number as much as Pygmies (around 90% of taxa counted) but eat a lower mushrooms quantities than theirs distant congeners Pygmies (around 800 g/day/family).展开更多
基金Institute of Technological Research–IPT,Fundcao de AmparoàPesquisa do Estado de Sao PauloBrazil[Process 2019/05840-3]+1 种基金Conselho Nacional de Desenvolvimento Científico e TecnológicoBrazil[Process 167470/2018-3]。
文摘As part of efforts to reduce anthropogenic CO_(2) emissions by the steelmaking industry,this study investigated the direct reduction of industrially produced hematite pellets with H_(2) using the Doehlert experimental design to evaluate the effect of pellet diameter(10.5-16.5 mm),porosity(0.36-0.44),and temperature(600-1200℃).A strong interactive effect between temperature and pellet size was observed,indicating that these variables cannot be considered independently.The increase in temperature and decrease in pellet size considerably favor the reduction rate,while porosity did not show a relevant effect.The change in pellet size during the reduction was negligible,except at elevated temperatures due to crack formation.A considerable decrease in mechanical strength at high temperatures suggests a maximum process operating temperature of 900℃.Good predictive capacity was achieved using the modified grain model to simulate the three consecutive non-catalytic gas-solid reactions,considering different pellet sizes and porosities,changes during the reaction from 800 to 900℃.However,for other temperatures,different mechanisms of structural modifications must be considered in the modeling.These results represent significant contributions to the development of ore pellets for CO_(2)-free steelmaking technology.
文摘A comparative study of the number of taxa and fungal biomass consumed by the Pygmies and the Bantus of Gabon has been realized in two Gabon north regions (Ogooue-Ivindo and the Woleu-Ntem). This study has allowed not only to establish the list of consumed fungal sorts by those populations, but also to estimate the daily consumed fungal biomasses by each ethnical group. The study has revealed a significant difference between a numbers of taxa and the quantity of mushrooms consumed by various ethnical groups: the Pygmies of the area who live especially by hunting and fishing consumed 96% of the recorded taxa with some high mushrooms quantities (around 3 kg/day/family);the Bantus who live nearby Pygmies also consumed some high mushrooms quantities (around 2 kg/day/family) but a low taxa number (56% of taxa counted by the Fang;69% by the Kota;39% by the Kwele);on the other hand, the Bantus living nearest the Pygmies consumed a high taxa number as much as Pygmies (around 90% of taxa counted) but eat a lower mushrooms quantities than theirs distant congeners Pygmies (around 800 g/day/family).
