Dobril Valchev. PASSIVE TECHNOLOGY FOR TREATMENT OF ACID MINE DRAINAGE FROM THE AREA AROUND -RADKA- MINE IN BULGARIA. 25th International Multidisciplinary Scientific GeoConference Proceedings SGEM2025, Science and Technologies in Geology, Exploration and Sustainable Mining, 2025, pp. 155-162. https://doi.org/10.5593/sgem2025/1.1/s02.20