双固相旋流反向沉降分离机理的研究

The hydrocyclonic solid-solid density separation technology has been applied mainly on the mineral processing. As a result of the concern about the environment and resource recycling in recent years，this technology began to have a number of application in the recycling of solid waste treatment，such as the separation of waste plastic and the recovery of the solar materials，silicon and silicon carbide from cutting waste of polycrystalline and monocrystalline silicon. There were some scattered reports in this field. But they are principally about large cyclones and on the process of particle settlement in single direction，and lack the research on the separation mechanism of reverse settling of two solid phases. This project is mainly concentrated on the separation mechanism by reverse settling of two solid phases, the dispersion mechanism of vortex shearing action, the effect on separation process of medium density and hydrocyclone design on a full scale range with the combined approach of theory analysis, test and CFD simulation. It is expected to reveal the general rule of the hydrocyclonic density separation，including the effect of design, operation and feed properties on the separation performance to provide the theory evidence for the determination of medium density(ranged from heavy medium to light medium) and particle concentration，the choice of cyclone size, the design and operation of the hydrocyclone, etc. Meanwhile，it also has important significance to enrich the theory of cycloning and improve the density separation technology.

旋流式固-固密度分离技术主要应用于选矿过程。近年来，由于对环境和资源循环利用的重视，该技术在固体废弃物资源化处理，如废旧塑料等的分离、太阳能材料如多晶硅、单晶硅切割废料中硅和碳化硅的分离等过程中开始有一些应用，也有零星的研究报道。但这些研究主要是关于大旋流器以及单一方向的颗粒沉降过程，缺乏对密度分离过程中关键科学问题——双固相的反向沉降分离机理的研究。本课题采用理论、试验和模拟相结合的办法，研究密度分离旋流器内双固相反向沉降过程、旋流剪切分散机理、介质密度的选择，以及全尺度范围内旋流器结构对分离过程的影响规律，揭示旋流式密度分离的一般规律，包括从重介质分离到轻介质分离过程中结构、操作和物性参数对分离性能的影响规律，为介质密度、颗粒浓度的设置、旋流器直径的选择、旋流器结构设计与操作提供理论依据。同时，这对充实旋流分离理论、提高密度分离效率等具有重要的意义。

旋流分离是利用物料间存在的沉降速度差在离心力场实现快速分离过程，常用于某一种目标产品分离或提纯，在工业上有着广泛的应用。虽然该原理也适用于两种固体颗粒混合物的分离，但实际生产过程中很难同时实现两种固体颗粒都达到很高的分离效率。本项目利用旋流场的剪切分散和离心沉降作用强化双固相的密度分离过程，具有重要的理论意义和实践价值，通过理论分析、数值模拟和试验相结合的方式，对工程实践中PET/PVC、Si/SiC、TiO2/SiO2、HDPE/PD分离和天然气水合物除沙等多种固-固混合物的逆向沉降分离进行了研究，得出了旋流分离器内双固相颗粒基于密度分离的最佳介质密度的计算方法，用试验数据修正了旋流器数值模拟的雷诺应力模型，验证了理论和模拟的可靠性，并进行流场仿真，得到了操作参数、物性参数、结构参数对流场及分离性能和操作性能的影响规律，丰富了基于旋流超重力场的密度分离理论，对固-固旋流分离过程的介质选取、旋流器结构设计和操作参数的选取提供了一般的理论依据。