Abstract: The heat treatment of fine-grained material wherein two quantities of fuel are delivered to a precalcination zone at two different levels. The first quantity of fuel is delivered at a lower level nearer the combustion zone and the oxygen content of the gases passing through this region of the precalcination zone are such that in this region a substoichiometric combustion takes place and a CO content between 0.05% and 1% is established. As a result a reducing decomposition of the NO.sub.x content of the exhaust gases from the combustion zone takes place.

Abstract: A silo for loose material in powder form having a base provided with a central conical section projecting upwards to form an annular discharge zone having floor portions inclined in a direction leading to an opening in a discharge chamber and in such manner that the material flows approximately tangentially towards the material discharge openings.

Abstract: The invention relates to a storage and mixing silo for bulk material comprising a mixing compartment in the form of an annular chamber. The radial width and the height of the chamber are proportioned to the diameter of the silo, the chamber has a material inlet opening and a material outlet opening circumferentially spaced from one another, and the chamber has a plurality of independently aeratable zones.

Abstract: This invention relates to a method and a device for the continuous feed of a controllable amount of powder material from a storage container to a consumer, using a vertical pneumatic conveyor, to which is fed conveying air, with loosening air supplied to the base area.