空气平面射流分选细粒煤的流场动力学特性及分离机制

China’s coal resource and water resource has a reverse distribution. Thus, it is urgent to develop efficient dry beneficiation technology of coal. Especially, the content of -6 mm fine coal in run-of-mine coal increases significantly due to the extensive deployment of the mechanized mining technology and this situation highlights the urgency of developing dry beneficiation technology of fine coal. However, the fine coal dry beneficiation methods reported in recent literature encounter many difficult problems in several aspects including product purification, recovery of dense medium, separation stability and separation suitability, which will restrict their developments. In this study, we attempt to adopt the air planar jet to beneficiate fine coal in a dry way and thereby, carry out basic scientific research on the hydrodynamic characteristics of separation environment and the mechanism of fine coal beneficiation. The concrete research contents are given in the following. The flow field coupling mechanism and hydrodynamic characteristics of the multiple streams of air planar jet are studied for the purpose of beneficiating the complex multi-component materials. The flow pattern, force characteristics and their spatial and temporal variation of the gas-solid two-phase flow system in a flow field of air planar jet are studied to reveal the separation mechanism of particles with different properties. The functioning manners and boundary conditions of main factors of disturbance in the separation stability of fine coal in a flow field of air planar jet are studied and the regulation method of separation stability based on the collaborative optimization of multiple factors is established. This study aims to establish the fundamental theories and methods about fine coal dry beneficiation using air planar jet and accordingly, provide a novel technical approach for fine coal dry beneficiation in dry regions.

我国煤炭资源与水资源呈逆向分布，亟需发展高效干法选煤技术，特别是煤炭综采技术的推广应用使得原煤中细粒煤(-6 mm)含量大幅增加，凸显了研究发展细粒煤干法分选技术的迫切性。然而，目前文献报道的细粒煤干法分选方法在产品净化、加重质回收、分选稳定性以及分选适应性等方面存在较多难题，制约其发展。本项目拟采用空气平面射流对细粒煤进行分选，对分选环境的流体动力学特性以及细粒煤分选机理进行基础科学研究。具体研究内容包括：研究适于多组分复杂物料分选的多股空气平面射流的流场耦合机制及流体动力学特性；研究空气平面射流场中气固两相流体系的流动特征、力学特征及其时空变化规律，揭示不同物性颗粒的分离机制；研究影响空气平面射流场中细粒煤分选稳定性的扰动因子作用机制及边界条件，建立多因素协同优化的分选稳定性调控机制。本项目旨在建立空气平面射流分选细粒煤的基本理论和方法，从而为干旱缺水地区细粒煤干法分选提供一种新途径。

我国煤炭资源与水资源呈逆向分布，亟需发展高效干法选煤技术，特别是煤炭综采技术的推广应用使得原煤中细粒煤(<6 mm)含量大幅增加，凸显了研究发展细粒煤干法分选技术的迫切性。然而，目前文献报道的细粒煤干法分选方法在产品净化、加重质回收、分选稳定性以及分选适应性等方面存在较多难题，制约其发展。本项目采用空气平面射流对细粒煤进行分选，对分选环境的流体动力学特性以及细粒煤分选机理进行基础科学研究。具体研究内容包括：研究适于多组分复杂物料分选的空气平面射流的流体动力学特性；研究空气平面射流场中细粒煤分选的能量作用及分离机制；研究空气平面射流场中细粒煤分选效果的影响因素及分选稳定性分析。. 本项目通过3年的研究取得了如下研究成果：(1) 揭示了适宜于细粒煤分选的空气平面射流的流动特征和气速分布特性；(2) 揭示了细粒煤颗粒在空气平面射流场中分离过程的运动学特性，建立了分选动力学方程，阐释了细粒煤在空气射流场中基于运动轨迹分离的分选原理；(3) 揭示了射流气速、射流角度、给料高度以及给料速度等操作参数对细粒煤空气射流分选效果的影响规律，确定了最佳操作条件；(4) 探索了空气平面射流对6~2 mm细粒煤的分选效果，分选可能偏差E值为0.2；(5) 揭示了影响空气射流分选稳定性的扰动因子种类、成因及其作用方式，提出了消除或减弱扰动因子作用的强化措施。. 本项目研究成果具有重要的科学意义。本项目通过将空气射流基本理论与矿物加工理论相结合，形成了空气平面射流分选细粒煤的基本理论和方法，建立了基于运动轨迹分离机制的细粒煤空气射流分选的试验装置和参数调控方法，取得了良好的分选效果。这些研究成果拓展了空气射流理论的应用范畴，丰富了矿物加工学科细粒物料重选方法。本项目提出的空气射流分选方法为干旱缺水地区细粒煤高效干法分选提供一种新途径。