A device for treating bulk material with a gas, the device including a grate through which gas can flow from an under-grate space to the upper side and which conveys a layer of bulk material in a conveying direction from a loading end to a discharge end. The grate has a plurality of mutually adjacent rows, each of which includes at least one bar that is elongate in the conveying direction and may be moved alternately back and forth in the conveying direction. Driving is controlled such that the forward stroke of the at least one bar of two adjacent rows takes place at the same time, while the rearward stroke of the at least one bar of two adjacent rows takes place at different times.

A conveyor floor for conveying bulk material like cement clinker in a conveying direction from a bulk material inlet to a bulk material outlet, with longitudinal reciprocating planks which extend in parallel to the conveying direction and are arranged one besides of the other with moving gaps in between provides enhanced conveying at lower costs, if each plank has a mean coefficient of friction C.sub.f for moving of the bulk material in the conveying direction relative to planks being significantly lower than the mean coefficient of friction C.sub.b for moving of the bulk material against the conveying direction relative to the respective plank.

A device for treating bulk material with a gas, the device including a grate through which gas can flow from an under-grate space to the upper side and which conveys a layer of bulk material in a conveying direction from a loading end to a discharge end. The grate has a plurality of mutually adjacent rows, each of which includes at least one bar that is elongate in the conveying direction and may be moved alternately back and forth in the conveying direction. Driving is controlled such that the forward stroke of the at least one bar of two adjacent rows takes place at the same time, while the rearward stroke of the at least one bar of two adjacent rows takes place at different times.