Method for preparing iron concentrate powder by reducing and magnetizing red mud in fluidized bed

Abstract

The invention discloses a method for preparing iron concentrate powder by reducing and magnetizing red mud in a fluidized bed. The method comprises the following steps of: magnetizing, reducing and baking dried and pre-heated red mud powder by an efficient circulating fluidized bed technology; burning exhaust gas in a combustion chamber, wherein the exhaust gas is generated after reducing and baking, a part of burned exhaust gas pre-heats the red mud powder through a multistage cyclone preheater, and the other part of burned exhaust gas is mixed with gas of a gas generating furnace; after adjusting the components of the gas, allowing the mixed gas to get into a circulating fluidized bed, wherein the mixed gas entering the fluidized bed reduces over 90 percent of Fe2O3 in the red mud into Fe3O4; after the reduced and magnetized red mud departs the fluidized bed, cooling the reduced and magnetized red mud in a cooler, wherein a cooling medium is the gas generated in the gas generating furnace; and after cooling the reduced red mud, performing magnetic separation on the red mud to obtain iron concentrate of which the grade is 61 to 65 percent. The iron concentrate is prepared from Bayer process red mud, the recovery rate of ferrum is more than 90 percent, the energy consumption in a baking process is reduced, and the environment is also protected.

Description

technical field [0001] The invention relates to a technical method of using a circulating fluidized bed as the main equipment, using red mud as the main raw material, performing magnetic separation on the reduction product by controlling a suitable reduction temperature and reduction atmosphere, and then preparing iron fine powder. The technological process belongs to the field of material preparation of chemical industry and metallurgy. Background technique [0002] Red mud is an insoluble residue. From the production process, it can be divided into sintering method, Bayer method and combined method. Usually the main component of red mud is Fe 2 o 3 , SiO 2 , A1 2 o 3 And CaO etc. The main components of the red mud discharged by the sintering method and the combined method are roughly the same, which contains a large amount of 2CaO·SiO 2 and other active mineral components, which can be directly applied to the production of building materials; the red mud produced by ...

AI Technical Summary

Problems solved by technology

The reaction kinetics of red mud is poor during the low-temperature roasting process, the required reaction time is long, and the energy consumption is large

The second type of reduction magnetization roasting, when the temperature is controlled at 950 ° C ~ 1000 ° C, while producing metallic iron, the non-magnetic material also reaches or approaches the melting point, and the formed liquid non-magnetic material slag phase will block and bond the reactor, so the reduction The reaction process is difficult to carry out continuously

In addition, regarding fluidized bed invention patents (9211333.2), (200710121616.4) and (201020570114.7) etc. mainly use fluidized bed to realize the reduction of iron fine powder of different particle sizes. Similarly, this kind of process also recovers the sensible heat of roasting tail gas, but the invention patent (9211333.2) and (201020570114.7) did not recover the latent heat in the roasting tail gas

Invention patent (200410041935) discloses a circulating fluidized bed mineral reduction roasting device and reduction roasting method, ore powder and coal powder are added from the lower part of the circulating fluidized bed, preheated air enters the fluidized bed from the bottom, and the high temperature after roasting After the tail gas exchanges heat with the air through the heat exchanger, it is released after being dust-collected by the cloth bag, and the latent heat of the roasting tail gas is also not recovered. In addition, the process is magnetized roasting for iron ore

[0004] The present invention uses a fluidized bed process to magnetize and roast red mud to prepare iron concentrate powder. Since the magnetization and roasting process of red mud is an energy-consuming process, the energy utilization efficiency of the overall process will determine the economy of the process. Existing The process only utilizes the sensible heat part of the tail gas after roasting, and does not make full use of the latent heat in the tail gas (such as CO, H in the tail gas 2 etc.), in addition, the process of recovering sensible heat has not achieved the effect of fully recovering

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