液相高压脉冲放电低品位菱镁矿的解离及界面特性演变行为研究

At present, it's extremely difficult to efficiently liberate and separate low-grade magnesite ores under the existing exploitation and utilization mode. Facing the increasingly serious environmental and resource constraints，the existing utilization mode will not survive into the future. As for that, this project proposes a novel method suitable for the resource utilization of low-grade magnesite ores, using high-voltage pulsed discharge in liquid (non-thermal plasma technology) to enhance the liberation operation. Adopting this new method, valuable minerals and gangue minerals in the ores can be forced into liberated particles due to the transient effect of discharge. Meanwhile, various active species produced by high-voltage pulsed discharge will contribute to the evolution of interfacial characteristics, which would be beneficial to subsequent treatment processes. This study focus on the liberation mechanism of low-grade magnesite ores subjected to high-voltage pulsed discharge in liquid, including physical and chemical effect, micro-zone characteristics on the mineral particles surface and dynamic behavior characteristics at solid-liquid interface. Combining liberation experiments with multi physics numerical analysis and molecular dynamics simulations, the principle of interactions at solid-liquid interface, the liberation process and its energy consumption pattern are investigated. Then, the liberation mechanism of low-grade magnesite ores and its behavioral evolution of interfacial characteristics using high-voltage pulsed discharge in liquid are revealed. This study will offer fresh ideas and theoretical reference for effective liberation and resource utilization of low-grade magnesite.

目前低品位菱镁矿的开发利用模式存在解离和分选困难问题，面对日趋严峻的资源和环境约束，现有模式已难以为继，为此提出适用于低品位菱镁矿资源化利用的新方法，即液相高压脉冲放电等离子体外场强化技术，可使有用矿物与脉石矿物解离成单体颗粒，同时产生的活性物质促进界面特性改变，为后续处理创造有利条件。本课题重点研究高压脉冲放电作用下菱镁矿石的解离机理，包括菱镁矿石解离的物理化学效应、矿物颗粒表面的微区特性、矿物颗粒固液界面动力学行为等；通过放电解离实验、多物理场数值仿真和分子动力学模拟方法，解析高压脉冲放电条件下矿石解离的能耗规律、放电解离过程和固液界面反应原理，揭示液相高压脉冲放电作用下矿物的解离机理和界面特性的演变过程。本项目研究可为低品位菱镁矿的有效解离及资源化利用提供新思路和理论参考。

我国的高品位菱镁矿资源过度消耗，低品位菱镁矿的资源化已迫在眉睫。现有低品位菱镁矿资源化利用方法为机械破碎与浮选结合的方式，效率有限，且存在潜在环境问题。针对低品位菱镁矿的资源化利用新方法，本项目明确了放电等离子体通道的直接冲击压力特性；结合高压脉冲放电破碎菱镁矿石实验解析了菱镁矿石的解离机理；利用显式非线性动力学方法数值模拟了水中高压脉冲放电对菱镁矿的冲击特性；采用分子动力学模拟阐明了羟基自由基在菱镁矿界面的吸附机理；通过晶体结构分析对比了不同破碎手段产生单体解离颗粒的差异性；利用静电分选明确了高压脉冲放电破碎后菱镁矿颗粒的电选特性。本项目研究为低品位菱镁矿的解离利用提供了新方法，为相应分选措施的选取提供了理论参考。主要研究结果总结如下：. （1）利用水中高压脉冲放电进行菱镁矿破碎时，等离子体放电通道作用位置主要位于不同组元矿物的边界处。在4μF电容容量与10mm间隙条件下，可有效破碎低品位菱镁矿的电压为-40kV，菱镁矿组元矿物解离的粒度范围为0~600μm。. （2）在4μF/-40kV/10mm间隙条件下，低品位菱镁矿破碎的能量效率约16.69%，菱镁矿表面承受的冲击载荷可达139MPa，脉冲放电破碎形成独立物相单体颗粒的性能优于机械破碎。. （3）菱镁矿破碎过程中产生的·OH与菱镁矿（211）解离面之间存在化学吸附过程，吸附过程中羟基O-H的距离由0.0983nm变为0.0856nm，吸附能为-4.381eV； . （4）脉冲放电破碎后的低品位菱镁矿微细颗粒经静电分选后，MgO质量分数大于46%，达到了高品位菱镁矿等级。