(中南大學 資源加工與生物工程學院，長沙 410083)
摘 要: 研究鈉鹽對高鋁褐鐵礦還原焙燒過程中鋁鐵分離的影響。結(jié)果表明：高鋁褐鐵礦經(jīng)還原后，鐵的金屬化率為87.13%，焙燒產(chǎn)物經(jīng)磨礦磁選后，金屬鐵粉中鐵品位和Al2O3含量分別為68.07%(質(zhì)量分數(shù))和7.94%，鐵的回收率僅為19.77%；添加硫酸鈉14%(質(zhì)量分數(shù))、輔助添加劑BS 2.5%(質(zhì)量分數(shù))后還原高鋁褐鐵礦，鐵的金屬化率可達95.69%，焙燒產(chǎn)物經(jīng)磨礦磁選后，金屬鐵粉中鐵品位升高到91.3%，Al2O3含量降低為1.27%，鐵的回收率達到93.64%。XRD、EDX及微觀結(jié)構(gòu)研究表明：未添加鈉鹽時，高鋁褐鐵礦中鐵氧化物易被還原為無磁性的γ-Fe，且鐵與鋁、硅結(jié)合緊密，磁選分離難度大；添加的鈉鹽能與Al2O3和SiO2反應(yīng)生成鋁硅酸鈉，破壞礦石結(jié)構(gòu)，有利于改善高鋁褐鐵礦的還原效果，但在碳酸鈉作用下鐵晶粒較小且易與脈石礦物結(jié)合，而在硫酸鈉作用下金屬鐵顆粒長大，與脈石礦物解離性能好，有利于鋁鐵分離。
關(guān)鍵字: 褐鐵礦；鈉鹽；還原焙燒；鋁
reduction roasting for high-aluminum content limonite
（School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China）
Abstract:The effects of different sodium salts on Al-Fe separation in limonite were studied during reduction roasting process. The results show that when the ore is reduced directly, the metallization rate of iron in roasted ore is 87.13%, and the total iron grade and Al2O3 content of metallic iron concentrate is 68.07% and 7.94%, respectively, but the iron recovery rate is only 19.77% when the roasted products are treated by magnetic-separation. The metallization rate of Fe in the roasted ore is up to 95.69% when reducing with addition of 14% (mass fraction) Na2SO4 and 2.5% BS. The total iron grade of metallic iron product increases to 91.3%, and the Al2O3 content decreases to 1.27%, the iron recovery rate reaches 93.64% when the roasted products are treated by magnetic-separation. The XRD, EDX and microstructure results indicate that, when limonite is reduced without sodium salts, the iron oxides are reduced to nonmagnetic γ-Fe, and most of the iron granules combine with aluminum and silicon gangues closely, which results in difficulties during magnetic separation. The sodium salts react with gangues bearing Al2O3 and SiO2 and form sodium aluminosilicates, thus, the structure of the ore is destroyed, and the reduction effect is greatly enhanced. However, the sizes of metallic iron grains obtained during the reduction with addition of sodium carbonate are relatively small and combined with gangue tightly. When reduced with sodium sulplate, the metallic iron grains grow and can be easily liberated from gangue. Therefore, Al-Fe separation is more effective after adding sodium sulphate.
Key words: limonite; sodium salt; reduction roasting; aluminium
