In cast iron foundries, used ferromagnetic batch materials can be transported and loaded into the furnace by lifting magnet. The precision of these operations by using electromagnetic grippers depends primarily on the variation in the mass of the batch material pieces. The article presents the characteristics of size of the batch materials used in the selected iron foundry. The obtained ranges mass values of individual pig iron ingots have been presented. It has been found that the mass of individual pig iron ingot may differ ± 25% from the declared by producer. The mass range of individual pieces of crushed or uncrushed return scrap was examined. Some pieces of uncrushed scrap have the mass more than three times the average weight of pieces of this scrap. Characteristics of the lifting capacity of these materials by a lifting magnet suspended to the crane was determined. Analysis of the obtained results indicates that for materials with less diversified mass of individual ferromagnetic pieces it is possible to use a gripper to weight a bigger portion with the same control setting. It was also found that there is a significant dispersion for a given gripper control, especially for materials with a wide range of individual pieces mass changes.