Acid Rock Drainage Remediation and Element Removal Using a Peat-Humic Agent with Subsequent Thermal Treatment of the Metal–Organic Residue

A novel, alternative method for acid rock drainage (ARD) remediation and metal recovery has been developed that uses a peat-humic agent (PHA) created by mechanical, chemical, and thermobaric treatment of peat from the Krugloe deposit (Novosibirsk region, Russia). The PHA effectively neutralised moderately acidic ARD and removed potential pollutants (e.g. Fe, Al, Zn, Cu, Pb, Cd, Ni, Co, and Hg), forming metal–organic residues. The organic matter can be removed completely from the metal–organic residues by heating them at 450–500 °C. After this treatment, the metal concentrate residues generally contained aggregates (20–350 μm in size), mainly composed of metal oxides and sulphates. Thermal decomposition of the organic matter in the PHA and metal–organic residues is an exothermic process with significant calorific value (9–15 kJ/g).