Study on microwave-assisted synthesis of NaX zeolite from solid waste lithium slag
In order to solve the problem of low resource utilization of solid waste(lithium residue)discharged in the production of lithium carbonate from Spodumene,a microwave hydrothermal method was proposed to synthesize NaX zeolite(NaX)using lithium residues as raw material.The solid and liquid phase materials during the synthesis of NaX zeolite were characterized using X-ray diffractometer,infrared spectrometer and solid-state nuclear magnetic resonance,and the reaction mechanism was explored.The structure of NaX zeolite synthesized from lithium slag was characterized,and its adsorption capacity of water and thermal stability were measured.The results show that the initial stage is a simultaneous process of lithium slag dissolution and the formation of sodium aluminate silicate,and the middle and late stages are a simultaneous process of lithium slag dissolution and the formation of gel of sodium aluminate silicate and NaX crystallization.Microwave accelerates the reaction rate but do not alter the process,and the time for synthesizing NaX is reduced by～2/3.The NaX zeolite synthesized from lithium slag has smaller grain size(0.5-0.8 μm),good stability,and the water adsorption capacity of 32%(mass fraction).This study provides technical support for the scaled production of NaX zeolite from lithium slag.
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