In the present work, the formation of the chemical composition of acid mine waters in the area of waste disposal of mining and processing of tungsten ores of Transbaikalia (Russia) is considered. It is shown that during long-term storage of processing waste in the pore space, acidic waters with a high content of rare-earth elements accumulate. During the recycling of waste in the washings, a change occurs in the ratio of light and heavy rare earth elements. When water is neutralized with limestone, solid phases of these elements are formed, which can be extracted.