Study of the Processes in Acid Mining Drainage Wastes During Its Neutralisation With Sodium Hydroxide

Abstract

It was studied the processes occurring in acid mining drainage adding NaOH into its composition. The methods on ICP-MS, turbidimetry and pH-meter were applied. After an increase in pH up to 6.0, a decrease in pH values was followed, and against the background of a decrease in pH, an increase in water turbidity was also observed. When sodium hydroxide was added, the pH increased disproportionately to its amount. The mechanisms of these changes were different in individual cases. Thus, in the pH range 3.52-2.64, a decrease in pH occurred, apparently, as a result of the oxidation of iron(II) to iron(III). In the pH range 6.2-6.41, when the iron(II) content in water was significantly lower, the above mentioned increase in turbidity cannot be explained by the oxidation of ferrous iron(II).