After taking into account the conditions of the domestic iron resources and the non-coking coal resources, the process of coal gasification-shaft furnace is an effective way to develop direct reduction iron in China. ...After taking into account the conditions of the domestic iron resources and the non-coking coal resources, the process of coal gasification-shaft furnace is an effective way to develop direct reduction iron in China. The following tasks are very critical to choose suitable process of shaft furnace and gasification, including the production of oxidized pellets with excellent comprehensive properties as well as the study of the reaction behavior and mechanism of swelling. The results showed that the oxidized pellets of using domestic magnetic iron concentrate as raw materials have favorable comprehensive properties, including higher mechanical strength both before and after reduction, faster reduction rate and lower reduction swelling index (RSI). All of these properties can meet the shaft furnace yielding requirement. When the temperature was below 1 223 K, the pellets′ RSI was lower than 20%. With increasing of the content of H2 in atmosphere, the pellets reaction rate accelerated, crushing strength enhanced and RSI decreased. The RSI dropped to 10.26% at 1 323 K in 100% H2 atmosphere, and it is up to 39.88% in 100% CO atmosphere. The iron grains mainly presented in platelike when pellets were reduced by H2, however, in CO atmosphere the iron grains were precipitated in flocculent. The whisker shape of iron grains and heating effects of reduction reaction are the major factors leading to the poor pellets strength and increase of RSI. Appropriately controlling the temperature and increasing the ratio of H2 to CO in atmosphere are good for dropping the RSI.展开更多
Iron ore reduction is a primary unit operation in current metallurgy processes and dominates the energy consumption and greenhouse gas(GHG)emissions of the iron-making process,Therefore,even a slight improvement of th...Iron ore reduction is a primary unit operation in current metallurgy processes and dominates the energy consumption and greenhouse gas(GHG)emissions of the iron-making process,Therefore,even a slight improvement of the energy efficiency or GHG emissions of iron ore reduction would yield considerable benefits to the cost of pig iron and,more importantly,to mitigation of the associated carbon footprint.The current study presents a discrete model that describes the iron ore reduction process for a single pellet.The transient reaction progress can be predicted and is validated against experimental measurements under various operating conditions,including different reducing gases and temperatures.The effects of pressure,isothermality,gas composition,and flow rate on reduction are investigated.The reduction rate increases significantly with increasing pressure until 5 atm,and the entire reduction process occurs more slowly under non-isothermal conditions than under isothermal conditions.This work provides a solid foundation for the development of a comprehensive particulate system model that considers both heat and mass transfer.展开更多
基金Item Sponsored by National Natural Science Foundation of China (51090384)Fundamental Research Funds for Central Universities of China (N090602005,N110202001)
文摘After taking into account the conditions of the domestic iron resources and the non-coking coal resources, the process of coal gasification-shaft furnace is an effective way to develop direct reduction iron in China. The following tasks are very critical to choose suitable process of shaft furnace and gasification, including the production of oxidized pellets with excellent comprehensive properties as well as the study of the reaction behavior and mechanism of swelling. The results showed that the oxidized pellets of using domestic magnetic iron concentrate as raw materials have favorable comprehensive properties, including higher mechanical strength both before and after reduction, faster reduction rate and lower reduction swelling index (RSI). All of these properties can meet the shaft furnace yielding requirement. When the temperature was below 1 223 K, the pellets′ RSI was lower than 20%. With increasing of the content of H2 in atmosphere, the pellets reaction rate accelerated, crushing strength enhanced and RSI decreased. The RSI dropped to 10.26% at 1 323 K in 100% H2 atmosphere, and it is up to 39.88% in 100% CO atmosphere. The iron grains mainly presented in platelike when pellets were reduced by H2, however, in CO atmosphere the iron grains were precipitated in flocculent. The whisker shape of iron grains and heating effects of reduction reaction are the major factors leading to the poor pellets strength and increase of RSI. Appropriately controlling the temperature and increasing the ratio of H2 to CO in atmosphere are good for dropping the RSI.
基金The author is grateful to the National Natural Science Foun-dation of China project(51904122)the Key Project of jiangxi Provincial Research and Development(20192BBHL80016)the Opening Research Project of State Key Laboratory of Multiphase Flow in Power Engineering for financial support of this work.
文摘Iron ore reduction is a primary unit operation in current metallurgy processes and dominates the energy consumption and greenhouse gas(GHG)emissions of the iron-making process,Therefore,even a slight improvement of the energy efficiency or GHG emissions of iron ore reduction would yield considerable benefits to the cost of pig iron and,more importantly,to mitigation of the associated carbon footprint.The current study presents a discrete model that describes the iron ore reduction process for a single pellet.The transient reaction progress can be predicted and is validated against experimental measurements under various operating conditions,including different reducing gases and temperatures.The effects of pressure,isothermality,gas composition,and flow rate on reduction are investigated.The reduction rate increases significantly with increasing pressure until 5 atm,and the entire reduction process occurs more slowly under non-isothermal conditions than under isothermal conditions.This work provides a solid foundation for the development of a comprehensive particulate system model that considers both heat and mass transfer.