Abstract: A process for sintering iron ore mixtures containing solid fuels on sintering strands in which uniform sinter is obtained throughout the depth of the charge by igniting the surface of the charge and subsequently treating it with hot gases under a set of defined conditions.

Abstract: A process for controlling the speed of strand sintering machines through utilization of the temperature of collected waste gas as measured in the collector pipe as the controlled variable provides improved response by utilizing as an additional controlled variable the temperature of the waste gases at the windboxes. Either the average temperature of those waste gases that leave the windboxes at a temperature above approximately 100.degree. C. or the location of the burn-through point as determined from the temperature of the waste gases at the windboxes can be used as the additional variable. In the latter case, the temperature of the collected waste gases can be used to automatically control the desired variable in a secondary cascade-type control loop in which the location of the burn-through point is the actual value and the travel speed is the regulated quantity.

Abstract: A dry grinding process for reducing ore to pelletizable particles comprises grinding the ore in a size-reducing unit and classfiying the ore in a centrifugal pneumatic separator which is automatically controlled to make the coarse fraction available at a substantially constant rate. The coarse fraction is recycled to the size-reducing unit and the total rate of fed ore and recycled coarse fraction is maintained substantially constant. The ore-feeding rate is varied when, and only when, a controlled variable of the pneumatic separator has a deviation in excess of a predetermined permissible deviation.

Abstract: A process for controlling the quality of sintered iron ore in which the Fe.sup.+ content of the sintered or is regulated by controlling the recycled-fines feed rate. The recycled-fines feed rate, determined by a prior art recycled-fines balance controller, is modified by a desired fines withdrawal rate generated in an Fe.sup.+ content controller as the difference between the actual Fe.sup.+ content of the sintered ore and a desired content. In a preferred form, the difference between the recycled-fines feed rate and the desired fines withdrawal rate is also applied to the Fe.sup.+ content controller.