Study On Fine Particle Classification Enhanced By High Shear Flow Field In Inclined Channel

The comprehensive mining technology of ore not only brings many conveniences,but also leads to an increase in the proportion of fine particles in the ore.Fine particle classification has become a hotspot in the field of mineral processing both domestically and internationally.Due to the small mass,high surface energy,and easy aggregation of fine particles,it is difficult to effectively separate them.The velocity gradient in the high shear flow field inside the inclined channel can significantly enhance the fine particle classification effect and reduce the mismatch and agglomeration phenomenon generated in the classification.This article first investigates the flow characteristics of high shear flow fields in inclined channels,and focuses on the force and velocity changes of particles at any position in the inclined channel,in order to accurately analyze the critical conditions for particles entering the overflow.Based on the characteristics of high shear flow field,the strengthening effect of velocity gradient on fine particle classification was analyzed,and the parameter model between target particle size,plate spacing,and channel water velocity was derived using the characteristics of particle resuspension motion.On this basis,batch classification experiments were carried out under different flow field parameters to verify the effectiveness of high velocity gradient enhanced fine particle classification and the adaptability of the flow field parameter model to fine particle classification.Afterwards,the influence of parameters such as concentration and fluidized water on fine particle classification was explored,and the application case study of closed circuit grinding classification was expanded to further discuss the high shear flow field in inclined channels that can enhance the fine particle classification process.The batch grading experiment explored the grading effect of iron powder under different plate spacing and water velocities,and compared the velocity gradient values under different parameter combinations.The results indicate that the velocity gradient in the inclined channel with a plate spacing of 2 mm remains at a relatively high level,with a d₅₀ of 0.074 mm The classification efficiency of RC can be stable at over 80%,with a maximum of 90.27%.By further analyzing the motion patterns of particles in high shear flow fields,a quantitative relationship between flow field parameters and water velocity is derived.And through experiments,the theoretical water velocity was compared with the experimental water velocity,and the results showed that there was only a deviation rate of 7.35%between the two.The continuous grading experiment focused on exploring the effects of feed concentration and fluidized water velocity on the grading effect of fine particles.The experimental results indicate that the increase in feed concentration inhibits the upward movement of some fine particles,resulting in an increase in the content of fine particles in the underflow.Therefore,the feed concentration should be between 20-35 g/l.Adding water can compensate for the water velocity loss in the fluidization section and ensure the stability of the shear flow field.The experimental results indicate that the amount of water added is directly proportional to the classification efficiency.The synergistic effect between the inclined and vertical sections can be used to obtain the required amount of supplementary water and fluidization water velocity for the classification test,in order to enhance the efficient classification of fine particles.Under the conditions of determining various theoretical parameters of the flow field,continuous classification experiments were conducted on the grinding and grading feed of iron ore plants.The experimental results show that the classification effect of RC on fine iron powder is significantly superior to the classification equipment such as spiral classifier,cyclone group,and high-frequency screen in mineral processing plants.Among them,when d₅₀ is 0.25 mm,the quality efficiency of RC classification is 69.13%higher than that of spiral classifier;when d₅₀is 0.074 mm,the classification efficiency of RC remains around 90%,and the negative efficiency is guaranteed to be around 30%.The research results of the thesis provide a theoretical basis for the industrial application of RC classification for fine particles.The high shear flow field in the inclined channel enhances the classification effect of RC on fine particles,greatly reducing the amount of sand return and energy consumption in closed circuit grinding,providing a new technology for fine particle classification.This thesis has 24 figures,28 tables,and 83 references.