Method for recycling dissolved flash steam exhaust in aluminum oxide production

The invention relates to a method for recycling dissolved flash steam exhaust in aluminum oxide production. The method comprises the steps that final stage flash steam exhaust or final stage flash obtained by a dissolving process in aluminum oxide production and previous multi-stage flash steam exhaust are fed to a pre-desilicication process for preheating original pulp, and the original pulp is heated to the pre-desilicication required temperature; condensed water formed after the final stage flash steam exhaust or final stage flash and previous multi-stage flash steam exhaust preheat the original pulp is taken as red mud washing water and one part of hot water for a whole plant. According to the method, the final stage flash steam exhaust is fully recycled, one or more stage flash steam exhaust before tail stage flash steam exhaust is taken as a boosting heat source and/or an independent heat source of the final stage flash steam exhaust, the usage amount of fresh steam of a desilicication section is zero, and the energy consumption, the production cost and the environmental pollution of an aluminum oxide plant are effectively reduced.