基于分选过程动态特性的弱磁筒式磁选夹杂机理研究

Recently the wet low-intensity magnetic separations are widely used in magnetic separations, which play an important role in the processing of iron ore, but due to the inclusion of gangue is easily happing in the processing to limit increase of concentrate grade, the demands of burden material for blast furnace production can't be met. Therefore, carrying out the basic theory of inclusions research has important theoretical and practical significance for guiding the improvement of equipment and improving iron ore sorting. This project, based on the dynamic characteristics of the low-intensity magnetic separation process, analyses the force of the ore grain in the sorting and interaction between particles and multi-field coupling relationship, combined with computer aided design technology, computational fluid dynamics, finite element method, discrete element method and so on, using COMSOL and MATLAB software for simulating of sorting process under multi-field coupling. Research the dynamic rule of separation process and the influence of parameters on the inclusion rule. Build the inclusion model with multi-field coupling and forecasting system to predict the effect of the main parameters on inclusion. Develops at least one typical small prototype of transparent tank of low-intensity magnetic separator. Representative magnetite samples are used for sorting tests. Combined optical microscope-high speed camera Particle Image Velocimetry (PIV) to verify and optimize the inclusion model. Explore new methods for optimizing low-intensity magnetic separations by Virtual Design and Computer Simulation. And constructing the inclusion theory based on sorting dynamics.

弱磁筒式磁选是目前使用最广泛的磁选方法，在铁矿选矿中占据重要的地位，但分选过程易夹杂，限制了弱磁选精矿品位的提高，难以满足高炉精料方针的要求，因此深入开展夹杂基础理论的研究，对指导设备的改进和改善铁矿分选具有重要的理论和实际意义。项目从弱磁筒式磁选分选过程的动态特性岀发，分析矿粒在分选阶段的受力情况及多场耦合关系，结合计算机辅助设计技术、计算流体动力学、有限元法、离散元法等方法，利用COMSOL和MATLAB等软件进行多场耦合作用下的弱磁分选过程仿真，研究分选过程颗粒的动态机制及参数对夹杂的影响规律，建立多场耦合作用下的夹杂模型及主要参数对夹杂影响的预测系统；研制1～2种典型的透明槽体弱磁筒式磁选机小型样机，用有代表性的磁铁矿试样进行分选试验，结合光学显微高速摄像、PIV等验证优化夹杂模型，探索弱磁筒式磁选利用虚拟设计、计算机模拟仿真优化研究的新方法，构建基于分选动态过程的夹杂理论。

项目从湿式弱磁筒式磁选机分选过程的动态特性出发，分析矿粒在分选阶段的受力情况及多物理场耦合关系，建立了矿粒磁选过程的动力学方程，采用有限元软件COMSOL建立了湿式弱磁筒式磁选过程的多物理场耦合模型，构建了设备结构参数、操作参数、工艺参数及矿粒性质等主要因素对湿式弱磁筒式磁选机磁选轨迹及磁选性能的影响的预测系统。利用多物理场耦合预测系统，进行了湿式弱磁筒式磁选机分选机理数值模拟研究，探究了磁场分布特性以及关键参数对磁选性能及矿粒轨迹的影响规律，首次提出了矿粒的等回收性和分层包裹现象是导致连生体夹杂及难以精选提高品位的重要影响因素。.为了减少磁选夹杂，提高精矿品位及回收率，根据数值模拟理论的研究结果，首次提出了精确磁力分选的概念，开发出了一种磁系磁场强度顺着矿浆流动方向从小到大增加的新型精确磁力弱磁选机，被回收强磁性矿粒所受到的磁力为该矿粒被回收所需的最小磁力。在采用多物理场耦合模型模拟优化新型精确磁力弱磁选机各结构参数、操作参数的基础上，研制出了一台JQ-300精确磁力弱磁选机，并针对铁品位为28.46%的景洪疆峰铁矿磁铁矿矿石进行分选试验。将原矿磨细至-200目占70%，通过一次精确磁力磁选可获得铁品位为65.24%，回收率为80.96%的铁精矿。而采用常规湿式弱磁筒式磁选机的最佳分选条件下获得铁精矿品位为65.22%时，回收率仅为68.37%的铁精矿，JQ-300精确磁力弱磁选机获得的回收率比常规湿式弱磁筒式磁选机高出了12.59个百分点。研制成功的JQ-300精确磁力弱磁选机具有选择性高，工艺流程短，生产应用方便，分选效果好等优点，为减少磁选夹杂提供了新的技术途径，具有广阔的应用前景。项目通过研究分选过程矿粒的运动规律及夹杂机理，明确了分选的微观过程与宏观结果的关系，构建了基于分选动态过程的夹杂理论体系，为弱磁选的分选与新型弱磁筒式磁选设备的研发应用及磁选夹杂机理研究提供了重要的理论依据。