With the large silo diameters of alumina silos featuring a central discharge it is normally tough to ensure an even discharge from a radial bottom segment. IBAU HAMBURG has solved this problem. For example, a cone measuring 7 m in diameter is installed in a silo with a diameter of 44 m on the inclined bottom of the silo to provide a storage capacity of 65,000 t.
The bottom of the cone is completely covered with individual fluidslides, as the annular area outside the cone. The material in the annular area is conveyed into the cone using a fluidslide discharge tunnel. The controlled inlet of the aerated material into this tunnel from the side is possible. The center cone and the radial covers of the fluidslide discharge tunnels are made of concrete or steel. The diameter of the center cone and the number of fluidslide discharge tunnels depend on the diameter of the silo and the maximum size of the individual aeration sections.
For example, 12 sections are provided for a 44 m silo. The silo bottom does not only slope towards the center outlet point but also towards the fluidslide discharge tunnel of each section. Alternating actuation is used for the individual aeration sections so that the entire material in the silo is put into motion during a complete cycle. This avoids all problems regarding dead zones.
The system provides for full silo emptying of up to 99% of the nominal storage capacity.