Installations for the calcination of alumina and similar products

摘要

A calcining installation of improved thermal efficiency comprises a long rotary tubular kiln having an upstream inlet, a downstream outlet and an air inlet at the downstream end. A burner is positioned in the upstream half of the kiln, the upstream part of the kiln constituting a calcining zone and the downstream kiln part constituting a cooling zone for the calcined material. A cyclone separator for separating dust from the kiln flue gases has an inlet and a dust outlet, and an additional cyclone separator has an inlet, a gas outlet and a material outlet connected to the upstream end of the kiln. A pipe connects the gas outlet of the additional cyclone separator to the inlet of the cyclone separator, the pipe having a vertical portion and an inlet for the raw material in the lower part of the vertical portion.