活化方式对稀土尾矿中硅铝活化的影响

Effect of Activation Mode on the Activation of Silicon and Aluminum in Rare Earth Tailings

稀土尾矿含有数量可观的可用于分子筛合成的硅铝物种,而目前天然矿物绿色合成分子筛的难点在于矿物活化。本文以稀土尾矿为原料,分别采用热活化、碱熔活化和亚熔盐活化三种方式对稀土尾矿进行活化,将稀土尾矿中处于高聚态的硅铝物种解聚为具有反应活性的单聚态硅铝物种,为稀土尾矿合成分子筛奠定基础,以实现稀土尾矿的二次利用。采用XRF、XRD、SEM-EDS等表征手段对活化稀土尾矿的化学成分、物相组成和表面微观形貌进行分析,研究不同方式对稀土尾矿活化的影响。结果表明,热活化稀土尾矿中SiO2晶型仍较稳定,活化效果不明显;碱熔活化和亚熔盐活化能较完全地活化稀土尾矿,且碱熔活化更能实现稀土尾矿的高效活化,同时升高碱熔活化温度能促进稀土尾矿的活化。当NaOH与稀土尾矿质量比为3,碱熔活化温度为450℃时,稀土尾矿中活性硅铝物种的溶出率为84.2%和63%。本研究结果可为天然矿物绿色合成分子筛及稀土尾矿资源二次利用提供一定的理论基础。

Rare earth tailings contain a considerable amount of silicon and aluminum species for molecular sieve synthesis,and the difficulty of green synthesis of molecular sieves from natural minerals lies in the mineral activation.In this paper,rare earth tailings,being used as raw materials,were activated in ways of thermal activation,alkali fusion activation,and sub-molten salt activation,respectively,to depolymerize the silica and aluminum species in the highly polymeric state of rare earth tailings into reactive mono-polymeric silica and aluminum species,setting the basis for the synthesis of molecular sieves,thus to realize the se-condary utilization of rare earth tailings.The chemical composition,phase structure,and surface micromorphology of the activated rare earth tailings were analyzed by XRF,XRD,and SEM-EDS characterization to investigate the effects of different activation modes on the activation of rare earth tailings.The results show that the SiO_2 crystal form in the thermally activated rare earth tailings is stable and the activation effect is not obvious;the rare earth tailings could be more completely activated by alkali fusion and sub-molten salt,and alkali fusion activation could realize more efficient activation of rare earth tailings.And at the same time,the increase of alkali fusion activation temperature can promote the activation of rare earth tailings.When the mass ratio of NaOH to rare earth tailings is 3 and the alkali fusion activation temperature is 450℃,the dissolution rates of reactive silica and aluminum species in rare earth tailings are 84.2%and 63%.The results of the study provide a certain theoretical basis for the green synthesis of molecular sieves from natural minerals and the secondary utilization of rare earth tailings resources.