Вестник МГТУ. 2020, Т. 23, № 1.

circulation of process solutions and the disposal of waste in the construction industry, the introduction of these technologies will facilitate a phased transition to a circular economy (McDonough et al., 2003). The created classification of substandard copper-nickel ores and technogenic formations of the Murmansk region according to their potential environmental hazard and suitability for processing by the method of physical and chemical geotechnology allows enterprises, potential waste processors, to minimize the cost of selecting technologies and justify the economic efficiency of creating new industries. In addition, to assess the risk posed by a number of natural and industry sites, studies of material composition were carried out, balances between the ability of mineral associations to produce and neutralize acids were estimated (Abrosimova et al., 2015; Karlsson et al., 2018; Lebre et al., 2017). The results are summarized in the table. The value of the resulting net acid potential (NAP) allows to predict the composition of the waste rock dump runoff. Comparing the estimates with actual observations, studying newly formed mineral phases, modeling hypergenesis processes in a laboratory setting made it possible to rank sites according to the potential environmental hazard level and from the standpoint of suitability for processing by heap bioleaching (Светлов, 2018). Table. Potential environmental hazard and suitability for bioleaching of low-grade copper-nickel ores and technogenic mineral formation Таблица. Потенциальная экологическая опасность и пригодность к переработке методом биовыщелачивания некондиционных медно-никелевых руд и техногенных образований Site NAP Potential environmental hazard Heap leachability Low-grade Monchepluton Cu-Ni ores Deposit Nyud II (Monchegorsk District) +81.99 Elevated. AMD*, heavy metal migration Good Deposit Nyud Terrace (Monchegorsk District) +36.51 Average. AMD, heavy metal migration Satisfactory Deposit Morozhkovoye Lake (Monchegorsk District) +63.57 Average. AMD, heavy metal migration Good Deposit Nittis-Kumuzja- Travjanaja (Monchegorsk District) +91.87 Elevated. AMD, heavy metal migration Good Technogenic mineral formation Allarechensk mine dumps (Pechenga District) +104.37 High. AMD, intensive heavy metal migration Good Concentration tailings of Cu-Ni ores (Pechenga District) +5.35 Moderate. AMD neutralization, heavy metal precipitation by hydrosilicates Satisfactory. Agglomeration required. Increased sulfuric acid feed rate Dump slags (Pechenga District) +4.84 Moderate. Sulfides in the silicate matrix limit AMD Satisfactory. Grinding and agglomeration required Notes. *AMD - acid mine drainage. All the necessary prerequisites are present in Russia for the widespread adoption of metal recovery by heap bioleaching. Obstacles include, of course, the adverse climatic conditions in Russia's mining regions, including the Murmansk region. At the same time, the experience of heap leaching of precious metals in Arctic and Subarctic climatic conditions with negative average annual temperatures shows the possibility of using these methods in the geotechnological processing of non-ferrous sulfide ores. Investigations of cryomineralogenesis in natural and anthropogenic sulfide-containing rock masses, the development of methods for the passive leaching of gold and silver-bearing rocks and mobilization of metals at below-zero temperatures using new oxidizing agents deserve attention and comprehensive experimental testing as applied to sulfide copper-nickel ores. The use of geochemical barriers is another example of nature-like technologies and one of the promising methods for protecting natural water bodies and treating wastewater from mining and minerals operations. The essence of the methods is to immobilize the pollutants. Geochemical barriers act as filters, making possible the use of existing and establishment of engineered geochemical barriers. Applications of artificial geochemical barriers, in addition to the purification of natural and waste water from heavy metals, radioactive elements, and oil products, include (Максимович, 2010; Baltrenaite et al., 2018; Chanturiya et al., 2014): - further recovery of valuable components from natural and anthropogenic mineral feeds using methods of physical and chemical geotechnology;