铁精粉制备α-Fe_(2)O_(3)纳米粒子及其机理

Preparation and Mechanism ofα-Fe_(2)O_(3) Nanoparticles by Using Iron Concentrate Powder

采用商业磁铁矿铁精粉(Fe_(3)O_(4)),设计了提纯和制备工艺,成功制备出质量分数为99.5%以上、分散性良好的α-Fe_(2)O_(3)纳米粒子,对其提纯、制备工艺及机理进行了深入研究.结果表明:w NaOH对除硅效果影响显著,当w NaOH为39%时,可使原料矿粉中w SiO 2由1.11%降至0.032%,得到较纯铁精粉;随烧结温度的升高,α-Fe_(2)O_(3)颗粒的结晶度、形貌特征及磁性能随之发生变化;当烧结温度为670℃时,α-Fe_(2)O_(3)颗粒综合性能最佳,颗粒结晶度较高、分散性较好,具有亚铁磁性;通过对氢氧化铁沉淀物加热搅拌时间的控制,可有效调控α-Fe_(2)O_(3)的晶粒尺寸;当搅拌时间为60 min时,获得分散性好、平均粒径仅为35.3 nm的α-Fe_(2)O_(3)纳米粒子.

Using commercial magnetite iron powder(Fe_(3)O_(4)),a purification and preparation process was designed,andα-Fe_(2)O_(3) nanoparticles with a mass fraction of more than 99.5%and good dispersibility were successfully prepared.The purification,preparation process and mechanism were studied in detail.The results show that:w NaOH has a significant impact on the effect of silicon removal,when w NaOH is 39%,the w SiO 2 in the raw ore powder can be reduced from 1.11%to 0.032%to get more pure iron fine powder.With the increase of the sintering temperature,the crystallization,appearance characteristics and magnetic properties ofα-Fe_(2)O_(3) particles have changed.When the sintering temperature is 670℃,the comprehensive performance ofα-Fe_(2)O_(3) particles is the best,including higher particle crystallinity,good dispersibility and ferrimagnetic properties.By controlling the heating and stirring time of the hydroxide sediment,the grain size of theα-Fe_(2)O_(3) can be effectively regulated.When the stirring time is 60 min,theα-Fe_(2)O_(3) with a high-quality dispersability and a average particle size of only 35.3 nm is obtained.