磁介质动态捕获新特征及其高度选择性捕获的机理研究

Until today, a static or nearly static matrix is used in high gradient magnetic separations (HGMS); such a matrix has a low loosing efficiency for particles, and is sensitive to the mechanical entrainment for non-magnetic particles and to the magnetic capture for partially liberated minerals. Thus, they have a relatively low separation selectivity and cannot be effectively applied for cleaning weakly magnetic ores. The dynamic matrix significantly improves the separation selectivity, but its capture mechanism is unclear, which has restricted the development of new HGMS technologies using dynamic matrix..A process device for dynamic matrix capture observation will be invented in this research. Firstly, the capture behaviors of dynamic and static magnetic elements to the coarse homogeneous magnetic and non-magnetic balls as well as to the magnetic intergrowth balls will be comparatively observed in the device using high viscous fluid; and the formation and elimination mechanism for the mechanical entrainment of non-magnetic balls on the magnetic elements will be typically observed, to understand the capture rules of dynamic matrix and its mechanism for highly selective capture. After that, the dynamic capture dynamics, selectivity and matching ratio between magnetic element and ball diameter will be theoretically analyzed. Secondly, such observations will be changed for the heterogeneous pure minerals, to modify the theoretical models combining Discrete Element Method (DEM) simulation. Finally, two kinds of dynamic capture models will be selected for separating fine weakly magnetic ores, to confirm the theoretical models and determine the optimal dynamic capture model. This research will provide new ideas and theoretical foundations for the development of new HGMS technologies using dynamic matrix, and contribute to the extended application of HGMS method for cleaning fine weakly magnetic ores.

迄今，所有高梯度磁选均采用(准)静态磁介质捕获模式，松散效率低，易夹杂非磁性矿和捕获连生体，导致选择性较低，无法深度精选弱磁性矿。磁介质动态捕获新模式可以显著提升选择性，但捕获机理不清，这限制了磁介质动态捕获高梯度磁选新方法的开发应用。.发明一种磁介质动态捕获过程观测装置。首先，在高粘性流体中对比观测磁介质动态和静态捕获粗粒均质磁性、非磁性和连生体球的行为特征，以及机械夹杂的形成与消除机制，掌握动态捕获规律及其提升选择性的机理，并开展动态捕获过程动力学、选择性和丝径匹配理论分析。然后，改为非均质纯矿物，通过捕获观测和离散单元法(DEM)模拟，修正理论模型。最后，选择两种模式开展动态捕获分选细粒弱磁性矿试验，论证理论模型的正确性，筛选最优动态捕获模式。本项目将为磁介质动态捕获高梯度磁选新技术的开发提供新思路和理论依据，促进高梯度磁选在细粒弱磁性矿深度精选领域的拓展应用。

迄今，所有高梯度磁选均采用(准)静态磁介质捕获模式，松散效率低，易夹杂非磁性矿和捕获连生体，导致选择性较低，无法深度精选弱磁性矿。本项目提出磁介质动态捕获新模式并开展捕获和分选机理研究，探索提升高梯度磁选选择性的新途径，具有重要的理论和应用价值。.本项目通过动态磁介质捕获和分选的理论、模拟和试验研究：(1)揭示了静态磁介质捕获选择性差和动态磁介质实现高度选择性捕获的内在机制，构建了磁介质动态捕获动力学模型。(2)采用自制的磁介质动态捕获分析装置准确分析了动态磁介质的捕获效能，通过观测、分析动态磁介质的捕获形态，论证了磁介质动态捕获的相关机理；论证试验表明，动态磁介质表面的矿粒群松散度高，有利于释放排出夹带的非磁性矿粒，因此其捕获选择性明显高于静态磁介质；如试验结果表明，旋转磁介质动态捕获可将捕获产品的TiO2品位由13.44%提升至27.45%，高于静态磁介质捕获的18.45%TiO2。(3)建立了旋转磁介质丝径与矿粒粒度匹配模型，开发出组合式旋转磁介质；研究发现，组合式旋转磁介质的捕获效能明显优于单一直径旋转磁介质。(4)筛选获得最优的磁介质动态捕获模式，改进了CenMag-300离心高梯度磁选机，联合试制了SLon-Z-100周期式脉冲振动高梯度磁选机。论证试验说明，这两种新型高梯度磁选机均可以高度选择性分选细粒弱磁性矿；如CenMag-300离心高梯度磁选机分选TiO2品位17.77%的攀钢钛粗精矿，获得TiO2品位27.57%的钛精矿，明显高于现脉动高梯度磁选的20.86%TiO2。.本项目成果将为动态磁介质捕获高梯度磁选新技术的开发提供新思路和理论依据，促进高梯度磁选在细粒弱磁性矿深度精选领域的拓展应用。

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