System and method of low-grade manganese dioxide ore fluidization reduction

The invention discloses a system and a method of low-grade manganese dioxide ore fluidization reduction. The system is mainly composed of a stock bin, a screw feeder, a feed valve, a fluid bed reactor, a discharge valve, a Venturi coal gas pre-heater, a preheated coal gas cyclone separator, a coal gas cyclone preheater, a reduction ore cooler, a Venturi powder preheater, a first-grade cyclone separator, a second-grade cyclone separator, a third-grade cyclone separator, and a waste heat boiler according to a set combination manner. According to the method, sensible heat of high-temperature reduction ore is recycled via direct contact of cooled coal gas with the high-temperature reduction ore, and at the same time coal gas is preheated; sensible heat of reduction exhaust is recycled via direct contact of high-temperature reduction exhaust with low-grade manganese dioxide ore powder, and at the same time, manganese dioxide ore is preheated; and sensible heat of CO and H2 in the reduction exhaust is recycled via water vapor generation of the waste heat boiler. According to the system and the method, reaction efficiency and exhaust heat utilization efficiency are high, and roasting process is economical; and the system and the method are suitable for large-scale industrialized production.