Table : Determined coefficients 𝐶 ∞,𝑖 , 𝐶 0,𝑖 and 𝑘 𝑖 of equation ( ) for both tailings as a function of the HCl concentration which corresponds to the stoichiometric ratio 𝑆𝑡 with anhydrite. The coefficients of 𝐶 ∞,𝑖 and 𝐶 0,𝑖 for the fits in Figure can be calculated with the maximum numbers in Table