Energy Consumption in Mining Comminution - Science Directthis the ore must be crushed to a size suitable for grinding. Grinding is then done to . operations: four gold and three iron ore mines. The average .. the ore is processed. Both open pit and underground mines have processing (milling) and refining facilities which are usually located onsite and are major energy consumers.open pit iron ore mining with grinding,Optimized wears increase production at KMARuda iron ore mine .“Actually, thanks to our improved productivity, we could change the technological scheme and move one grinding mill from the primary stage to the secondary one,” says Main Grinding Specialist Vladimir Saveliev. chosen as wear and process expertise partner. Across from its huge open-pit iron ore mines, KMARuda.