PROCESS FOR TREATING A BITUMINOUS MIXTURE IN A PLANT, THE ESSENTIAL COMPONENT OF WHICH IS A DIRECT CURRENT HEATED DRUM MIXER, AT THE TERMINAL REGION TO WHICH A SUCTION DEVICE IS CONNECTED

摘要

The process serves for the preparation of a bituminous mixture using a drum mixer which is fired in cocurrent and to whose end region an extraction system is connected. So that the solids containing a bituminous binder are coated in an optimum and low-dust manner with minimal thermal load, it is provided that the mineral solids (4) are seized by internals known per se as early as directly in the inlet region on the burner side (6) of the drier tube (9) and are conveyed over the free cross-section of this tube in a uniform, loose distribution as far as approximately over half the length of the drier tube (9). During this operation, the solids (4) are dried to a residual moisture content and transferred at the end of this drying zone A into a mixing and circulation zone B. Approximately at the beginning of the mixing and circulation zone B, the mineral materials (4) are mixed with the binder (41), and the mixture is converted into a bituminous mixture (40) as it passes on. In the region of the transition from the drying zone A into the mixing and circulation zone B, all or some of the heating gases (5) are extracted out of the drier tube (9) and the temperature and moisture content of the mixture (40) in the mixing and circulation zone B is regulated by appropriate metering-in of the heating-gas sub-streams (16, 18).