强化密度离析的弱磁性铁矿石流态化分选机理研究

The dense medium gas-solid fluidized-beneficiation technology is introduced to solve the separation and purification difficulties of weak-magnetic iron ore. It shows the advantages of good selectivity and high separation precision for various types of ores, without using water, less pollution and wide application field. Weak magnetic hematite ore will be selected as the subject investigated. Based on the mineralogy characteristics of rude ores and the properties of medium solids, the combined approach of experimental tests, theoretical analysis, numerical simulation, and actual ore separations will be employed in the project. The project mainly focuses on the following aspects: the nonlinear dynamical characteristic in the separation system of the quasi-dispersion bubbling fluidization to reveal the formation mechanism and evolution law of the time-averaged stable separation system in the three-dimensional space of fluidized bed; the coupling and collaborative optimization of multi-factors of equipment structure, separation technology, disturbance factors will be conducted to reveal the movement regulation and separation mechanism of multi-component and multi-scale iron ore particles in the stable fluidized-beneficiation system; regulatory mechanism based on the collaborative optimization of multiple key factors will be established to enhance the fluidization stability and separation reliability. The achievements of this project aim to provide a new approach for the dry separation and purification of iron ore in the water-shortage regions of China.

针对弱磁性铁矿石的分选提纯难题，提出将浓相气固流态化分选技术引入铁矿石分选回收领域，具有对矿石选择性好、分选精度高、无需用水、污染小、应用范围广等优势。本课题以弱磁性赤铁矿石为研究对象，以原矿的矿物学特性及加重质颗粒的介质属性为基础，拟采用试验表征及测试、理论分析、计算机数值模拟、分选试验相结合的方法，研究准散式鼓泡流态化分选体系中的非线性动力学特性，揭示流化床三维空间内时均稳定分选体系的形成机理及演化规律；通过设备结构、分选工艺及扰动因子等因素的耦合及协同优化，揭示多组分多尺度铁矿石颗粒在流态化稳定分选体系中的运动规律与分选机理，建立强化流态化稳定性及分选可靠性的关键因素协同优化的调控机制，为我国干旱缺水地区的铁矿石干法分选提纯提供一条新途径。

弱磁性贫杂铁矿石的高效低成本分选提质是后续冶金过程的前提，也是选冶领域的焦点和难点问题。采用物理方法预先抛除部分脉石矿物，将极大地提高后续破碎磨矿、磁选、浮选等工艺的分选效率，降低分选成本。本项目提出将浓相气固流态化分选技术引入铁矿石预先抛尾领域，具有对矿石选择性好、分选精度高、无需用水、污染小、应用范围广等优势。.本项目深入研究了弱磁性赤铁矿石的物相组成、元素含量、脉石嵌布规律等，通过选取代表性的弱磁性赤铁矿石，获得了铁矿石的铁品位-密度分布规律，指出了弱磁性赤铁矿石在不同分选密度下的理论分选指标。选取气雾化铁粉和锆英砂组成的混合加重质作为粗粒级弱磁性赤铁矿石的分选介质，实现了流化床的床层密度在2.6-3.8g/cm3的范围内调控。考察了不同加重质配比对二元加重质形成的流化床床层密度的影响规律，建立了床层密度的可靠预测模型，可以准确调控流化床的床层密度。通过单因素分选试验确定了流化床操作条件对铁矿石分选效果的影响；通过开展多因素响应曲面法试验，研究了操作参数对分选效果的影响规律及其交互作用，最终确定了铁矿石的最佳分选条件，粗精矿全铁品位高于51%,回收率高于79%。通过对不同粒度级的铁矿石开展分选实验，结果表明：随着粒度级减小，铁矿石分选精度降低，分选得到的精矿品位和铁回收率均减小，因此传统气固流化床分选铁矿石的粒度下限为10mm。.本项目提出改善细粒级铁矿石分选效果需要引入其它外力场，如振动力场，机械搅拌等，以改善流化床的床层密度稳定性。研究了振动力场与气流场耦合作用下，1-6mm细粒级弱磁性赤铁矿石的流化特性与分离规律，结果表明：通过脱除细粒级脉石，基于密度离析的干法振动分选技术能够实现细粒级弱磁性赤铁矿石的高效分选提质。在适宜的操作条件下，能够保证较高的粗精矿品位及回收率，分别高于52%与65%。项目研究成果能够拓展到其它贫杂矿石的预先抛尾及煤系共伴生矿物的预富集等领域，为贫杂矿产资源的分选回收提供一条新途径。