Abstract
This article examines the accuracy of determining the reactivity of lime milk, which is used as the primary reagent for the removal of heavy metal ions from mine water. A comparison of four titrimetric methods was conducted, differing in sample preparation conditions (grinding, boiling), sample mass, and the use of correction coefficients. It was found that the average reactivity of lime milk ranged from 38.2% to 45.7%, with an overall mean value of 42.9% across all experiments. These results are significantly below the regulatory range of 52–70% established for this reagent. The most reproducible results were obtained using the method involving two sample masses and preliminary grinding of the sample. The low reactivity values are attributed to the presence of impurities (Mg, Si, Al, Fe, gypsum, sand), which reduce the effective Ca(OH)₂ content. The study concludes that stricter quality control of lime used for lime milk preparation is necessary, as well as an adjustment of the technological regulations for reagent dosing at treatment facilities.