Acid- and base-neutralization capacity in mine water and brines

摘要

Acidimetric and alkalimetric titration to the endpoint of pH 4.2 and 8.3 is commonly used in water chemistry to determine the amount of inorganic carbon species in water [1]. However, in mine water and brines the determination of inorganic carbon species should not be based on this method because buffering components such as polyvalent metals (e.g. iron, copper, manganese), non-carbonic acids (hydrogen sulfide, sulfuric acid, phosphoric acid, boric acid, silicic acid, organic acids, etc.), and the acid-base behavior of metals (aluminum, manganese, zinc, nickel, etc.) may be dominant and lead to completely wrong results with respect to the carbon species. As a kind of go around the hot peroxide acidity procedure is widely used for measuring the acidity of mine drainage. In this context, the poorly defined terms "net alkalinity" and "net acidity" are commonly used in particular in the mine-water community [2].