冲击流强化浮选调浆的数值模拟与试验研究

Numerical simulation and experimental study of impact flow enhancing flotation pulp conditioning

设计了一种实验室型冲击流浮选调浆装置,通过流体高速冲击强化药剂在颗粒表面的吸附,实现颗粒表面高效改质。利用Fluent软件对冲击流浮选调浆装置内的流场进行了数值计算,分析了流体分布特征、流体运动速度、应变速率及最小涡尺度等流体动力学参数,测试分析了不同冲击流入料速度调浆后颗粒的捕收剂吸附密度、表面疏水性和浮选动力学特性,考察验证了冲击流入料速度对颗粒表面改质的影响。结果表明:冲击流浮选调浆装置混合区内存在明显的水平流和循环流,有利于强化药剂吸附和颗粒表面改质,流体运动主要受径向运动和轴向运动的影响,随着冲击流入料速度的增大,流体径向运动和轴向运动速度增大;在冲击段,流体具有较高的应变速率,在发散段,流体应变速率逐渐减小至趋于稳定,靠近壁面,应变速率增大,增大冲击流入料速度可以增大应变速率;在冲击段,最小涡尺度随着流体运动不断减小,在发散段,最小涡尺度随着流体运动先增大后减小,在X轴距离为20 mm时达到最大,最小涡尺度随着冲击流入料速度的增大而减小;捕收剂吸附密度、接触角、浮选速率常数和最大可燃体回收率均随着冲击流入料速度的增大而增大,入料速度达到4 m/s时,达到最大,分别为0.88 mg/g,103.27°,0.051 6 s^(-)1,94.18%,之后出现下降趋势,冲击流浮选调浆装置最佳入料速度为4 m/s。

A laboratoryimpact flowconditioningpulpdevice was developed to enhance the adsorption of collectors on the surface of particles using the high-velocity impact flow to achieve an efficientmodification of mineral particlesurface.The flow field of the impact flowconditioningpulp device was calculated using the Fluent software to analyze the fluid distribution characteristics,as well as the fluid dynamics parameters such as fluid velocity,strain rate and Kolmogorov scale(η).Moreover,the collector adsorption density,surface hydrophobicity,and flotation kinetics of mineral particles after pulp conditioning with different impactvelocities were analyzed to verify the effect of impactvelocity on the modification of mineral particles.The results show that thehorizontal and circulating flows were present in the mixing zone of the impact flowconditioningpulp device,which was beneficial to enhance the adsorption of collector and the surface modification of particles.The fluid flow was mainly affected by the radial and axial flow,as well as the radial and axial flowvelocity all increased as the increase of impactvelocity.In the impact section,the strain rate of fluid was higher.In the divergent section,the strain rate of fluid gradually decreased up to the stable value,and the strain rate increased with the fluid flowed to the wall surface.The increase of the impactvelocity may increase the strain rate.In the impact section,theηdecreased with the fluid flow.In the divergent section,theηincreasedwith the distanceup to the X-axis distance of 20 mm above which theηdecreased,and theηdecreased with the impactvelocity increased.The collector adsorption density,contact angle,flotation rate constant,and maximum combustible recoveryincreasedwith the impactvelocityincreased to 4 m/s above which thosedecreased,and the optimum impactvelocity of the pulp conditioning was 4 m/s with the collector adsorption density,contact angle,flotation rate constant and maximum combustible recovery were 0.88 mg/g,103.27°,0.0516 s^(-1)and 94.18%respectively.