Flow and compression properties of feed solids for roll-type presses and extrusion presses

In the chemical, pharmaceutical and food industry, many problems in transport, storage and handling of pulverised products are caused by formation of dust. Using roll-type presses to compact such materials, dust-free products can be realised. The operating conditions are mostly found in experiments and cannot be transferred by scaling up. ng with the theory of Johanson, a differential equation can be derived from the equilibrium conditions of the rollers. lt describes the stress function in relation to geometric parameters and the plastic yield laws of the material. The boundary conditions and the influence of different parameters will be discussed. The throughput capacity of the rollers is determined by the prepressure at the feed point given by the feeding equipment. However, there must also be an influence of the roller speed, which is not considered in the theory. In this connection, flow speed properties of the bulk material must be introduced to calculate the effect on the throughput.