Method for recycling iron and aluminum by particle size grading pretreatment of Bayer process red mud

The invention relates to a method for recycling iron and aluminum by particle size grading pretreatment of Bayer process red mud, belonging to the technology for recycling red mud resources. The method comprises the following steps: firstly, Bayer process red mud is graded in terms of the particle size by using a physical method into coarse red mud and refined red mud; the coarse red mud is processed using physical mineral dressing processes, such as magnetic separation, gravity separation and the like, in order to obtain iron ore having high iron quality and coarse-grained sand, which are made use of respectively; the refined red mud is mixed with sodium carbonate, limestone and carbon power and is then subjected to reduction sintering, and two processes of magnetizing reduction roasting of iron and soda lime sintering of aluminum are implemented synchronously by means of the control of sintering conditions; sodium aluminate is dissolved out of clinker through dilute alkali solution, dissolved slag is subjected to magnetic separation to recover iron ore concentrate, and after being subjected to dealkalized cleaning, the residual calcium silicon slag is applied to building material industry. The method realizes combined recovery of iron, aluminum and other elements, magnificently achieves the comprehensive utilization of the Bayer process red mud, is capable of effectively relieving environment pollution resulting from the accumulation of the Bayer process red mud, and has excellent economic and social benefits.