Appropriate reduction and Fe-Al separation of high iron gibbsite

Abstract

High iron gibbsite is a Fe-Al composite ore with quite big reserves in China, in which superfine aluminum and ferrous minerals are conjoint with each other. Thus, they are difficult to separate through physical beneficiation. In order to meet iron and aluminum consumption, a new process was proposed, in which gibbsite samples and pulverized coal were mixed uniformly, reduced isothermally at high temperature, cooled rapidly and then dressed by magnetic separation. The effects of reduction conditions, including reduction time, reduction temperature and FC/O (mole ratio), were investigated. The results revealed that regarding samples with 34.68% iron and 23.85% alumina, metallic iron concentrate with 78.23% iron and non-magnetic product with 53.32% alumina were obtained. The yielding ratio of iron and alumina are 89.24% and 86.09% respectively. Metallic iron concentrate can be used as steelmaking burden by further treatment, and alumina can be further extracted from the nonmagnetic product.