Modeling Cryogeochemical Processes in the Oxidation Zone of Sulfide Deposits with the Participation of Oxygen-Bearing Nitrogen Compounds

摘要

The development of oxidation zones at sulfide deposits is largely controlled by active processes of sulfide oxidation, which produce chemically aggressive solutions of sulfuric acid (with pH 2 and lower). Some researchers believe that acid rains may play a significant role in the transformations of ore and gangue minerals in technogenic landscapes, with genesis of acid rains in urbanized and industrially developed areas related to the anthropogenic emission of CO2, SO2 (up to 60%), and NO_x (up to 30-50%). It was experimentally established that nitrogen oxides and their interaction products with water play the role of catalysts during the oxidation and leaching of ore minerals, first of all, sulfides. The freezing of weakly acidic (pH 3.0-5.0) natural sulfate water with low [(0.2-5) x 10~(-4) M] concentrations of N(III) compounds in cryogenic environments results in highly concentrated (with respect to HNO2 and H2SO4) solutions and creates favorable conditions for active oxidation processes, as is also confirmed by the recently experimentally established fact of an anomalous increase in the HNO2 oxidation rate (by a factor of 10~5) at negative temperatures. These facts and considerations led us to suggest that nitrogen compounds can notably affect the chemical transformations of the near-surface levels of the cryolithozone.