旋流流化床离心分选细粒赤铁矿的特性和机理研究

China is abundant in iron ore resources, however fine and hard treated low magnetic hematite makes up more than 20% of the whole iron ore resources, in order to attain high quality iron concentrate it needs to be processed by further cleaning concentrate, so developing a new high-efficiency technology through the research of further fundamental theory has an important theoretical and practical significance of improving the utilization rate of this kind of resources. It employs centrifugal concentrator in reconcentrating the fine hematite and this progress occurs in a cyclone fluidized bed, which is developed based on the theory of cyclone and fluidized bed centrifugal separation, the method can be divided into the following two aspects: separation characteristics and separation mechanism, the separation characteristics in the progress mainly contains that choosing operation factor, the enriching behavior of iron minerals in the concentrates and tailings, the cyclone characteristics including separation cutting particle size , the critical operating conditions and control methods of mineral particles group during cyclone classification changing to centrifugal separation characteristics; the separation mechanisms are as followings: the law of centrifuge field established by the spin of particles, the construction and regulation of thick flow diaphragm separation fluidized bed, and hindered sedimentation dynamics of heavy minerals in the fluidized bed and the key discharging technology of heavy minerals in the centrifuge field. This experiment aims to provide theoretical direction and rationale for the new technology optimization and the promotion of application, it will be achieved the new separation technology of fine low magnetic hematite by means of clarifying the performance and mechanisms.

我国铁矿资源丰富，但全国总铁矿储量的1/5 以上为细粒难选的弱磁性赤铁矿，需要深度精选才能得到高品质铁精矿，因此，通过深入的基础理论研究，形成高效的分选新技术方法，对提高这类资源的利用率具有重要的理论和实际意义。采用基于流化床离心分选和旋流器原理开发的旋流流化床离心分选法深选细粒赤铁矿，研究内容包括：1、分选特性，包括操作因子筛选、铁矿物在精矿和尾矿中的行为走向、分选过程的旋流器特征如分离切割粒度及矿粒群由旋流分级向离心分选特征转变的临界操作条件与调控方法；2、分选机理，包括矿浆自旋建立离心力场的原理、离心强化厚流膜分选流化床的构建与调控、流化床内重矿物的干涉沉降动力学及离心力场中大量重矿物的排放关键技术。项目研究的目标是通过旋流流化床离心分选法的特性及机理研究，为其技术优化及产业化奠定必要的理论基础和提供理论指导。

我国铁矿资源丰富，但全国总铁矿储量的20%以上为难选赤铁矿，亟待选矿高效开发利用。为将流化床离心分选技术应用于细粒赤铁矿，基于流化床离心分选和旋流器原理开发了旋流流化床连续离心分选法。采用自主研制的旋流离心分选机为试验设备，进行了旋流流化床离心分选特性和机理研究。采用单因素条件和多变量正交试验筛选了操作因子，得到旋流连续分选的主要操作因子分别为给矿浓度、给矿压力、沉砂口压力、溢流口压力、溢流管深度、溢流管直径、沉砂管直径、分选锥环数等因素。通过产品品位、回收率、粒级组成等指标分析铁矿物在精矿和尾矿中的富集状态和行为走向，计算了分离粒度d50 等指标，分析了流化床离心分选的旋流分级特征，探明了赤铁矿分选过程的调控方法及分选指标的变化规律。根据流体力学理论确定了矿浆压力与离心强度关系，查明了矿浆自旋、流化床结构、离心强度和流态化水压力三者协同构建离心强化厚流膜流化床的原理，表明当设备结构参数一定时，流体压力与流速、流量及等效离心强度均成正比关系，流体压力对构建离心力场起关键作用，决定旋流连续离心分选效能的主要参数有给矿压力、流态化水压力、给料粒度和密度等。运用流体力学、数理统计等理论，进行流化床离心分选的干涉沉降动力学分析、流化床内矿粒的受力及相互作用机制，查明矿物颗粒在流化孔中分选主要受离心力、向心浮力和流体阻力作用。通过自由沉降和干涉沉降分选因素分析，建立了流化床离心分选的干涉沉降动力学模型，分析了各因素对分选指标的影响机理。采用计算流体力学数值模拟方法，探明了旋流流化床离心分选的流场特征。分选腔中流体速度分布的计算结果表明，设备分选柱内流体的切向、轴向和径向速度分布合理，流场稳定，其旋流产生的流态对离心力场的构建起了决定作用。本项目研究结果为旋流流化床离心分选技术应用于大量难选赤铁矿的分选提供了一定研究基础，并为其将来技术优化或产业化提供了一定指导。