Method for recycling Bayer process red mud

Abstract

The invention discloses a method for recycling Bayer process red mud, which is characterized in that aluminum powder, red mud powder and silica powder are mixed according to a certain mass ratio, metal oxides in the red mud are reduced by aluminum in an SHS mode, and reaction products mainly comprise three parts, namely Fe-Si-M alloy, slag and smoke dust; the Fe-Si alloy or the Fe-Si-M alloy can be used as a deoxidizing agent for steelmaking and the like; slag can be used as a raw material for producing aluminum oxide; according to the method, the SHS technology is adopted for treating the red mud, external heat supply is not needed after ignition until the reaction is completed, the reaction is rapid and thorough, and compared with other technologies, the method is energy-saving and efficient; the vast majority of aluminum and sodium in the red mud are returned to an original aluminum oxide production system in the form of a sodium aluminate solution.

Description

technical field [0001] The invention relates to the technical fields of metallurgy and environmental protection, in particular to a method for reusing Bayer process red mud. Background technique [0002] Red mud is an alkaline waste residue produced by the alumina production industry. It is named red mud because it contains iron oxide in the form of red mud. For every ton of alumina produced, 1.5-2 tons of red mud is produced. According to the current alumina production, the stockpile of red mud in the country increases by nearly 100 million tons every year. A large amount of red mud stockpiles not only wastes land, increases business costs, but also It is also a great hidden danger to ecological security. At present, there have been several ecological disasters caused by red mud in the world, so it is urgent to control red mud. At present, there are many technologies for processing red mud, but few of them have realized industrialization. The main reason is that the econom...

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Problems solved by technology

[0007] Hu Jianbao used aluminum ash (21.75% for metal Al, 12.79% for AlN, and 30% for Al2O3) as a reducing agent in "Research on the Synthesis of Calcium Aluminate by Melting Reduction of Red Mud" to heat and reduce Fe2O3 in red mud in an intermediate frequency furnace. Calcium aluminosilicate slag and ferrosilicon alloy are formed with SiO2, and quicklime is added at the end of smelting to prepare calcium aluminate cement; one of the disadvantages of this technology is that it cannot fully use the reaction heat of aluminum itself to maintain the reaction, and requires external equipment to provide heat to maintain the reaction In this process, aluminum ash (metal Al is 21.75%, AlN is 12.79%, Al2O3 is 30%) is mixed with red mud and quicklime according to 1.0~1.2 times of the theoretical demand for aluminum, which determines that this plan cannot be adopted. SHS technology; the second disadvantage of this technology is the use of smelting reduction, the reaction speed is slow, the reaction is not complete, and more than 25% of the silicon has not been reduced; the third disadvantage of this technology is that the technical solution does not use the nearby alumina plant to recycle The aluminum and oxygen elements in red mud are used instead of slag to produce cement. Due to the large fluctuation of red mud composition, the cement index is likely to be unstable, and the construction of a cement plant needs to meet certain conditions such as scale, equipment, and site; the disadvantages of this technology Fourth, this technical solution requires continuous purchase of slag-type regulator quicklime

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