赤泥-煤矸石协同还原焙烧回收Fe、Al有价元素

Valuable element recovery of Fe and Al by reduction roasting of red mud and coal gangue

赤泥和煤矸石是典型的铝硅酸类固体废物,两者协同还原焙烧有助于实现其所含Fe、Al等有价元素的回收。采用热力学计算、热重分析、X射线衍射分析、电感耦合等离子体发射光谱分析等方法,考察了赤泥-煤矸石协同还原焙烧过程中,焙烧温度、焙烧时间、赤泥-煤矸石质量比对还原焙烧产物物相组成及其所含Fe、Al等有价元素回收效率的影响。结果表明,混合物料中铝硅酸盐物相和含铁物相随焙烧温度的升高呈现规律性变化,如高岭石相转变规律为,高岭石→偏高岭石;钙霞石相转变规律为,钙霞石→钙黄长石;水化石榴石相转变规律为,水化石榴石→铝酸钙;赤铁矿依次转变为,Fe_(2)O_(3)(非磁性)→Fe_(3)O_(4)(磁性)→FeO(非磁性)→Fe(磁性)。当焙烧温度为600℃、焙烧时间为60 min、赤泥-煤矸石质量比为7:3时,铁精矿产出率为15.6%、铁品位达55.6%、Al溶出率为73.6%。在此基础上,建立了“赤泥-煤矸石协同还原焙烧-磁选-酸浸”的工艺,可实现煤矸石、赤泥中Fe、Al等有价元素的同步回收。

Red mud(RM)and coal gangue(CG)are typical aluminosilicate wastes.The synergistic reduction roasting of RM and CG has a wide application foreground in the recovery of Fe,Al and other valuable elements.In this paper,the effects of roasting temperature,roasting time and the mass ratio of RM and CG on the phase composition and the recovery of Fe,Al and other valuable elements were investigated by thermodynamic analysis,thermogravimetric analysis,x-ray diffraction and inductively coupled plasma optical emission spectrometry.The results showed that aluminosilicate and iron-containing phases change regularly with the increasing roasting temperature.The phase transformation rule of kaolinite was“kaolinite-metakaolinite”;cancrinite is“cancrinite-gehlenite”,hydrogarnet was“hydrogarnet-calcium aluminum oxide”;and hematite changes in the order of“Fe_(2)O_(3)(non-magnetic)-Fe_(3)O_(4)(magnetic)-FeO(non-magnetic)-Fe(magnetic)”.The yield and the grade of iron concentrate were 15.6%and 55.6%,respectively,and the dissolution percentage of Al reached 73.5%,when the roasting temperature was 600℃and the roasting time was 60 min at the RM/CG mass ratio of 7:3.Based on this,a process of“RM-CG reduction roasting-magnetic separation-acid leaching”was established to recovery Fe,Al and other valuable elements from RM and CG.