1 mm弹性筛分过程筛面挠曲形态与筛孔空间变形规律

Deflection of screen surface and spatial deformation law of screen apertures during 1 mm elastic screening

  • 摘要: 潮湿煤炭筛分过程中,在水分与黏土矿物的作用下,细粒物间黏附作用强、团聚效应显著、颗粒离析分层困难、筛面堵孔严重,导致物料透筛困难、筛分效果较差,严重制约了煤炭的大规模提质加工。针对上述问题,结合振动测试分析与多柔体动力学仿真方法,开展了弹性筛面运动学特性及1 mm弹性筛分试验研究;分析了简谐振动作用下弹性筛面挠曲形态对激振参数的响应特征,阐明了弹性筛面挠曲形态及筛孔空间变形规律,重构了筛面挠曲响应曲面及弧形筛孔空间形态;结合筛分试验研究了激振参数等对1 mm弹性筛分效果的影响规律,确定了最佳的激振参数,对比分析了弹性、刚性筛面对不同水分煤炭1 mm筛分效果的影响。结果表明:简谐振动作用促使弹性筛面产生大变形挠曲运动,弹性筛面相比筛体可以产生较大的变形,筛面的挠曲变形特征能够有效克服边缘区域筛分盲区的问题,保障了筛面的有效开孔面积,且三维弧形筛孔显著增加细颗粒的透筛概率;在激振力、激振频率、振动方向角分别为8.5 kN、14.08 Hz、50°时,筛分效率最高可达80.15%。随着物料外水含量的增大,弹性筛面的大振动强度促使细粒聚团物碎裂解聚,强化物料松散与透筛,其筛分效果明显优于刚性筛面,证实了弹性筛面可以满足1 mm干法筛分的技术需求。

     

    Abstract: Under the action of water and clay minerals, the process of wet material screening has some problems such as strong adhesion between fine particles, significant agglomeration effect, difficulty in particle separation and layering, and severe clogging on the screen surface, leading to difficulties in material sieving and poor screening performance, which can severely restrict the large-scale upgrading and processing of coal. To overcome the problems above, combining vibration testing and multi-flexible body dynamics simulation methods, the kinematic characteristics of elastic screen surface and 1 mm elastic screening test were carried out. The response characteristics of the deflection deformation of elastic screen surface to the excitation parameters was analyzed under harmonic vibration, and the laws of elastic screen surface deflection deformation and screen aperture spatial deformation were revealed. The deflection of the screen surface and the spatial morphology of holes were reconstructed. The influence of excitation parameters on the screening effect of 1 mm elastic screening was studied through screening experiments, and the optimal excitation parameters were determined. In addition, the 1 mm screening performance of rigid and elastic screen surfaces on the materials with different moisture contents were compared and analyzed. The results showed that the effect of harmonic vibration promoted the large deformation and bending motion of the elastic screen surface. And the elastic screen surface could generate greater vibration acceleration and deformation compared to the screen body. During the vibration process of the elastic screen surface, the deflection deformation characteristics of screen surface could effectively overcome the problem of screening blind zones in the edge area and ensure the effective opening area of screen surface. The three-dimensional curved screen holes significantly increased the probability of fine particles through screen. The screening efficiency was up to 80.15% when the excitation force, excitation frequency and vibration direction angle were 8.5 kN, 14.08 Hz, and 50°, respectively. As the external moisture content of the material increased, the high vibration intensity of the elastic screen surface promoted the depolymerization of agglomerated fine-grained particles, strengthening the looseness and permeability of material and its screening performance was significantly better than that of the rigid screen surface, which could meet the technical needs of 1 mm dry screening.

     

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