ABSTRACT The recycling application of bauxite residual is limited by its high content of iron, unfortunately, the complicated embedding feature of haematite makes it quite difficult to be removed efficiently and cleanly. In this paper, the process of selective reducing-magnetic separation without acid leaching is adopted to remove iron from bauxite residual. Different parameters such as carbon mass addition, roasting temperature, reduction time, magnetic field intensity and grain size on the iron removing ratio and iron yield are systemically investigated. It is indicated that haematite in bauxite residual is reduced to magnetite basically after 700°C roasting for 2.5 h by 1.0 wt-% carbon powder reducing, and the optimal conditions of magnetic separation are magnetic intensity of 235 mT and grain size of +150 μm, respectively. After selective reduce roasting–magnetic separation, iron content in the bauxite residual is sharply decreased from 7.98 to 1.34%, the iron removal ratio is 83.21%, and iron-rich magnetic concentrate contains about 30.48% iron, meanwhile, 87.03% of the iron in bauxite residual is enriched in the magnetic concentrate. The process is characterised by efficient and clean removal composite iron impurities from bauxite residual without using acid leaching.

中文翻译：

---

选择性减少焙烧 - 磁选以有效和清洁地去除铝土矿残留物中的铁质

摘要 铝土矿残渣的回收利用受到其高铁含量的限制，不幸的是，赤铁矿复杂的嵌入特征使其难以有效清洁地去除。本文采用不酸浸的选择性还原-磁选工艺去除铝土矿残渣中的铁。系统研究了不同参数如碳量添加、焙烧温度、还原时间、磁场强度和晶粒尺寸对除铁率和铁产率的影响。结果表明，铝土矿残渣中的赤铁矿经700℃焙烧2.5 h后，经1.0 wt-%碳粉还原后基本还原为磁铁矿，最佳磁选条件为磁强235 mT，晶粒度+150 μm ， 分别。选择性还原焙烧磁选后，铝土矿残渣中铁含量由7.98%急剧下降到1.34%，除铁率为83.21%，富铁磁精矿含铁约30.48%，同时含铁87.03%在铝土矿残渣中富含磁性精矿。该工艺的特点是不使用酸浸，高效、清洁地去除铝土矿残渣中的复合铁杂质。