垂直管道颗粒沉降速度的影响因素

 针对深部资源开采的“高井深”问题,研究了垂直管道水力提升过程中颗粒沉降速度的影响因素。基于球形颗粒的水中沉降机理,分别建立层流区、过渡区及紊流区的颗粒沉降速度表达式,对影响沉降速度的颗粒粒径、颗粒密度及水温进行敏感性分析,并考虑颗粒形状及浓度对沉降速度的影响。结果表明,在层流区和过渡区,各因素对沉降速度影响的敏感度随颗粒密度ρ_s与水密度ρ之间比值不同而变化,当层流区ρ_s >2ρ及过渡区ρ_s >3ρ时颗粒粒径 >颗粒密度 >水温,当层流区ρ_s<2ρ及过渡区ρ_s<3ρ时颗粒密度>颗粒粒径>水温;在紊流区,各因素对沉降速度影响的敏感度为颗粒密度 >颗粒粒径 >水温;球形颗粒沉降速度理论值大于不规则颗粒沉降速度实际值,可采用颗粒形状系数加以修正,且在干涉沉降过程中采用Richardson-Zaki 公式,使计算结果符合工程实际。

Influencing factors for particles settling velocity in vertical pipes

For the issue of "greater well depth" faced by deep mining activities, the influencing factors on the settling velocity of particle in the hydraulic lifting system have been studied. Based on the settlement mechanism of spherical particle in water, the settling velocity expressions of laminar area, transition area and turbulent area are respectively determined. A sensitivity analysis is carried out in terms of particle size, particle density and water temperature, and the influence of particle shape and its concentration on the settling velocity is discussed. The results show that in the laminar area and transition area, the sensitivities of particle size, particle density and water temperature to the settling velocity vary with the ratio of particle density to the water's; That in the turbulent area, the sensitivities of those influencing factors exhibit as particle density >particle size >water temperature; And that the actual settling velocities of irregular particles are less than those theoretical values of the spheroidal particle of same size. To make the results better fit engineering practice, the particle shape factor is employed to amend the differences between the theoretical values and the actual ones, and Richardson-Zaki formula is adopted in the hindered settling process.