基于微波选择性热效应的页岩钒强化提取机制研究

In this project, the mechanism of vanadium extraction from shale enhanced by microwave selective thermal effect will be studied in three aspects: strengthening the structural dissociation of vanadium-bearing mica, strengthening the oxidation conversion of low-valent vanadium and intervening control of "silicon binding". The response of vanadium shale to microwave field in roasting process will be clarified by studying the absorption characteristics of typical vanadium shale and its constituent minerals, and the effect of microwave field on the main phase reaction and structure change of vanadium shale in roasting process will be investigated. The enhancement effect of microwave selective thermal effect on mass transfer in the oxidation of low valent vanadium will be analyzed at macro scale, and the selective enhancement dissociation mechanism of Al-O(OH) octahedral structure layer of vanadium-bearing mica by microwave roasting will be investigated at micro scale with density functional theory. The formation mechanism of "Silicon binding" of vanadium shale will be revealed through solid state reaction and vanadium migration rule during microwave roasting, and the control mechanism of "Silicon binding" of vanadium shale with microwave intervention will be established. The implementation of this project will further improve the theoretical basis of vanadium extraction from vanadium shale by microwave roasting, which is a clean and efficient method for extracting vanadium from shale, and provide theoretical basis for optimizing the process control of microwave roasting of vanadium shale.

本项目从微波焙烧强化含钒云母结构解离、强化低价钒氧化转价和介入控制“硅束缚”三个方面，深入研究微波选择性热效应强化页岩钒提取机制。通过典型钒页岩及其构成矿物的吸波特性研究，明确钒页岩在焙烧过程中对微波外场响应能力的变化规律，考查微波外场对钒页岩焙烧过程主要物相反应和结构变化的影响。从宏观尺度分析微波选择性热效应对低价钒氧化反应传质效果的强化作用；结合密度泛函理论，从微观尺度考查微波焙烧对含钒云母中钒所在的Al-O(OH)八面体结构层的强化解离机制与低价钒反应活性强化机制。通过微波焙烧过程钒页岩物相转变、固相反应及钒迁移规律研究，揭示钒页岩“硅束缚”形成机理，建立微波介入钒页岩“硅束缚”控制机制。本项目的实施将进一步完善钒页岩微波焙烧提钒这一清洁高效页岩提钒方法的理论基础，为实现钒页岩微波焙烧的过程优化控制提供理论依据。

本项目以典型云母型钒页岩为研究对象，系统地研究了微波选择性热效应强化页岩钒提取技术与机理。通过典型钒页岩及其构成矿物在微波外场中的温升特性，以及不同温度条件下的复合介电常数测试，明确了钒页岩在焙烧过程中对微波外场响应能力的变化规律。基于微波外场对钒页岩焙烧过程主要物相反应和结构变化的影响，揭示了微波选择性热效应对低价钒氧化反应传质效果的强化作用机理，以及微波焙烧对含钒云母中钒所在的Al-O(OH)八面体结构层的强化解离机制与低价钒反应活性强化机理。通过微波焙烧过程钒页岩物相转变、固相反应及钒迁移规律研究，揭示了钒页岩焙烧过程中“硅束缚”现象的形成机理。基于上述内容的研究，形成了微波选择性热效应强化页岩钒转化-提取技术，与常规焙烧-酸浸工艺相比，焙烧温度降低115°C，焙烧时间缩短32min，H2SO4浓度降低10 vol%，浸出时间缩短4 h；建立了钒页岩高温硅束缚形成机制与微波介入调控技术，使“硅束缚”形成温度提高约100°C，进一步拓宽了钒页岩高温转化的有效温度区间。