A process for the direct reduction of iron ore in a shaft furnace having an upper reducing zone and a lower cooling zone in which reducing gas is introduced to the furnace at the bottom of the reducing zone around the periphery of the furnace, exhausted reducing gas or top gas is removed from the top of the furnace, cleaned, mixed with additional hydrocarbons, and reinjected into the furnace below the reducing zone. The hot reducing gas is injected serially into different sectors of the cross-section of the furnace and at varying velocities to force upflowing cleaned top gas to change its flow path or its flow rate, or both, periodically. Apparatus for accomplishing the method is also disclosed.