Base and sub-base slag aggregates, are manufactured in AEIFOROS BULGARIA ‘s plant in Pernik. The slag is transported from the steelworks to AEIFOROS storage area located less than 3km away and is stored before processing. As first step of processing, the slag goes through screening installation. Through screening two different fractions of slag (0-40mm and 40-150mm) are separated while the overband magnet installed on the screening line removes the iron from the slag. The iron is recycled in the melt shop of the steelworks. The slag fraction 0-40mm goes to the slag crusher and is crushed to another two fractions: 0-4mm and 4-10mm. Fractions 40-150 mm, 0 40mm, 4-10mm and 0-4mm are the final products delivered to the customers. All fractions are certified according to factory production control Regulation 305/2011/EU.