回收沥青中残留矿粉沉降理论分析及去除方法研究

Analysis of Sedimentation Theory and Elimination Method of Residual Filler in Extraction of Asphalt Cement

为了解决沥青回收过程中矿粉的残留问题,利用非匀相体系沉降分离原理分析了矿粉在沥青回收溶液中的沉降规律;结合分子热运动导致的布朗运动,计算了离心沉降时矿粉的临界沉降粒径和不同粒径矿粉所需的分离时间。结果表明:分离时间随矿粉粒径的减小而增加;随着离心加速度的增加,矿粉临界沉降粒径减小,分离时间缩短;规范规定的离心加速度和分离时间达不到要求的分离效果;离心加速度增至7 000g后,矿粉的临界沉降粒径为0.03μm,可满足分离要求,此时离心分离30 min矿粉可完全去除。回收沥青试验验证结果显示改进方法对沥青回收过程中矿粉的分离效果较好。

In order to eliminate the filler in the extraction process of asphalt cement, the sedimentation rule of filler in the asphalt solution was analyzed with the sedimentation principle of particles in heterogeneous system. The critical particle size of filler was estimated according to the displacement of the particles due to Brownian diffusion and centrifugal sedimentation, then the sedimentation time of particles with different diameters were calculated. Computation result shows that （1） the sedimentation time increases with the decrease of particle size, and the sedimentation time and critical particle size of filler decrease with the increase of centrifugal acceleration; （2） the centrifugal acceleration and sedimentation time stated in the specification cannot achieve the sedimentation purpose; （3） when the centrifugal acceleration of centrifugal machine reaches up to 7 000 g, the critical particle size of the filler is 0.03 μm, and the filler can completely subside in 30 rain. The extracting experiment of asphalt indicates that the sedimentation effect of filler using the propositional method is excellent.