Roasting of fine material, esp. crude cement flour - where mixt. of preheated flour and powdered fuel is fed via pneumatic conveyor into rotary drum furnace

摘要

The material flows through a multistage cyclone preheater and is then roasted in a rotary drum furnace. Hot exhaust gases from furnace flow through preheater to heat the raw flour. The flour leaving the last preheater cyclone is fed into a pneumatic conveyor together with powdered fuel; and a gas with a low oxygen content is employed to carry the mixt. of flour and fuel from the conveyor into furnace. The waste gas leaving preheater, contg. 4-6% O2, and at 320-380 deg.C, is pref. used as the conveyor gas. Gas pref. has a speed of 15-30 m/s, and a pressure of 1100-1400 water-column; 0.03-0.06 normal cu.m of gas is pref. used per kg flour. Improved precalcination of the flour entering the drum furnace is obtd.