First,the characteristics of low-velocity conveying of particles having different hardness are experimentally investigated in a horizontal pipelin in terms of flow pattern and pressure drop to show that the slug flow can be classified into two types depending on the settling of particles alon the pipeline,and the period is small for slug flow without the settled layer,which is called solitary slug flow.The pressure drop for soft particles shown to be larger than that for hard particles.Then,experimental results are presented on horizontal fluidized-bed conveying of fine powders t show that air release from the top surface of the conveying channel is an important factor for high mass flow rate of particles. First, the characteristics of low-velocity conveying of particles have different hardness are experimentally investigated in a horizontal pipelin in terms of flow pattern and pressure drop to show that the slug flow can be classified into two types depending on the settling of particles alon the pipeline , and the period is small for slug flow without the settled layer, which is called solitary slug flow. The pressure drop for soft particles shown to be larger than that for hard particles. Chen, experimental results are presented on horizontal fluidized-bed conveying of fine powders t show that air release from the top surface of the conveying channel is an important factor for high mass flow rate of particles.