The nodules are spherical bodies that are scattered within the sedimentary zone of the seabed, and their growth is closely associated with the biogeochemical processes and water sediments. These nodules are mainly composed of Mn, Fe, SiO 2 , Ca, Ni, Cu, Co and Al. Manganese nodules are an excellent source of base metals and sought-after and rare elements and the fact that they are used as a base elements matrix will be in high demand in industry. Previous studies have shown that primary con-centrations of chemical such as Fe in the system are beneficial for increas-ing manganese extraction. However, it is necessary to optimize the opera-tional parameters so as to maximise Mn recovery. This work investigates the effect of using of tailings, obtained after slag flotation ata foundry plant on the dissolution of Mn from marine nodules, where statistical analysis was distributed using factorial experimental design ontime, MnO 2 /Fe 2 O 3 ratio, and H 2 SO 4 concentration.