Several stainless-steel slags have been successfully employed in previous studies as substi-tutes for lime in the treatment of industrial acidic wastewaters. This study deepens the knowledge ofsuch application, by analyzing the neutralizing capacity of different slags related to their mineralcompositions. To do so, firstly the chemical and mineral compositions of all the slag samples areassessed. Then, 0.5 g, 1 g, 2 g of each slag and 0.25 g and 0.5 g of lime are used to neutralize 100 g of0.1 M HCl or HNO3 solutions. After the has neutralization occurred, the solid residues are extractedand analyzed using XRD spectroscopy. Then, the solubility of the minerals is assessed and ranked,by comparing the XRD spectra of the residues with the obtained pH values. The results showthat minerals such as dicalcium silicate and bredigite are highly soluble in the selected experimentalconditions, while minerals such as merwinite and åkermanite, only partially. Moreover, Al-rich slagsseem to perform poorly due to the formation of hydroxides, which generate extra protons. However,when the weight of slag is adequately adjusted, Al-rich slags can increase the pH values to higherlevels compared to the other studied slags.