Effect of different activation methods on the leaching properties of aluminum and silicon in Bayer red mud
In this paper,aiming at the problem that Bayer red mud has low aluminum-containing and silicon-containing phase dissolution rates under alkali excitation conditions,and cannot meet the requirements of[AlO4]and[SiO4]monomers for the preparation of geopolymers,it is proposed to acti-vate red mud by microwave activation,roasting activation and mechanical activation,respectively.The effects of different activation methods on the leac-hing rate of Al2O3 and SiO2 in red mud were mainly studied,and the phase transition and activation mechanism of red mud in the three activation methods were discussed.The results showed that when the microwave activation temperature was 800℃,the leaching rates of SiO2 and Al2O3 in red mud were the highest,0.54％and 25.1％,respectively.The leaching rates of SiO2 and Al2O3 were the highest at 400℃ and 1 200℃,which were 0.42％and 23.3％,respectively.However,mechanical activation did not have a significant effect on the improved activity of Al2O3 and SiO2 in red mud,and the highest leaching rates of Al2O3 and SiO2 were only 2.32％and 0.63％.The XRD in the red mud activation process showed that under microwave and roasting activation conditions,at 400～800℃,the decomposition of molten iron garnet and calcium nepheline in red mud mainly occurred,and the calci-um aluminum yellow feldspar and soda-calcium silicate phases were formed by microwave and roasting activation,respectively.At 800～1 200℃,calci-um-aluminum yellow feldspar decomposes to form dicalcium silicate and calcareoxene phase,while calcium silicate phase is stable in red mud,and when microwave and roasting are activated,cubic structure and orthorhombic structure sodium aluminosilicate phase are formed in red mud.
Bayer red mudmicrowave activationroasting activationmechanical activationdigestion efficiency
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维普
