In a charging process of a shaft furnace, in particular of a blast furnace, batches of charge material are typically discharged in cyclical sequence into the furnace from a top hopper using a flow control valve. A method and system is proposed for adjusting the flow rate of charge material in such a process. According to the invention, a respective set of plural valve settings is stored for each batch, each valve setting of a set being associated to a different stage in the discharge of the batch. The method and system are configured to discharge a given batch so that, at each stage in the discharge of the given batch, the flow control valve operates at a constant valve opening according to the valve setting associated to that stage and so that an actual average flow rate at which charge material is discharged is determined for that stage. Further according to the invention, the method and system are configured to correct the plural valve settings offline and in function of the actual average flow rate determined for the associated stage.