Environmentally sound geotechnologies for leaching metals from polymetallic ore processing wastes and wastewater

Abstract

Global challenges (increased consumption of georesources, climatic changes, limited reserves) increase the relevance of the problems of growing waste accumulation and environmentally-sound modernization of mineral extraction. In this regard, the existing approaches to the design of geotechnologies for metal mining need to be improved based on a concept of so-called circulation waste management and ecologization of technological processes. The paper is devoted to the issue of formation of conceptual bases and directions of ecologization of geotechnologies at leaching metals from polymetallic ore processing wastes and wastewater. The study presents recommendations for improving in-situ leaching of ores in blocks, allowing to determine the optimal conditions for increasing the completeness of subsoil use and reducing environmental damage. It was revealed that at metal extraction with solution circulation through brine chambers the content of Na, Cl, SO4 and Ca ions in dialysate was low, while without circulation through brine, it significantly exceeded corresponding MPCs. This proves the fundamental feasibility of controlling natural leaching processes by enhancing the oxidizing potential of natural solvents through the addition of industrial oxidizing agents. It was found that increasing the duration of agitation leaching (both with and without mechanoactivation) leads to a uniform expansion of the local maximums of Pb yield from the pulp when the minimum NaCl concentration decreases from 11–12 to 7% at H2SO4 concentration of 0.6%. One of key results of the study is justifying the expansion of the use of disintegrators to realize targeted activation of tailings. The practical significance of the obtained results lies in the proved feasibility of optimizing the flow sheet of electrochemical extraction of metals from wastewater on the basis of the obtained regularities of the use of brine circulation through brine chambers. In addition, the totality of the obtained results of using a disintegrator for reextraction of lead from geomaterials will allow developing a methodology for calculating the parameters of mechanoactivation action to increase the degree of metal recovery from the tailings of North Ossetia-Alania’s (Zgidskoe, Sadonskoe, Arkhonskoe deposits) polymetallic ores beneficiation. The most promising way for further research is to substantiate methods of using underground space for complete removal of wastes (wastewater and tailings) after their multistage treatment.