Decarburisation

Fiebig updraft classing tanks are used for cleaning sand (0 to 2 mm). Light substances such as wood and coal with a specific gravity of about 1.2 to 1.5 g/cm³ as well as finest grits are separated.

The container is about 3 meters high and in diameter. The freshwater cabin, which is under constant pressure and percolation, is situated in the lower section of the container. The water thus constantly enters the updraft cabin through the bottom of the jet. The sand to be cleaned is fed into the container from above and evenly distributed by the updraft water. The lighter particles ascend and are discharged into the drain at the overflow. The heavier particles drop to the bottom of the jet, float there, and form the so-called slurry. The slurry deposit grows higher and higher as operating time goes by, and a specially designed testing probe determines the fill level of the slurry. When a threshold value is reached, the hydraulically or pneumatically driven drain valves at the bottom of the jet are opened and the refined sand flows into a dewatering device such as a Fiebig dewatering wheel or a Fiebig dewatering screen.