Experimental results of the axial and lateral mixing of dispersed fine particles in a binary-solid riser are resented.Using point source tracer injection

the lateral solids dispersion is determined by measuring the solids RTD at different radial positions.A proposed two-dimensional dispersion model describes the measured RTDs satisfactorily.The laterar fine particle Peclet number increases with increasing the fraction of coarse particle and changes little with increasing gas velocity.A correlation of the lateral Peclet number governs the measured experimental data well.