Enhanced Pyrite Depression Through Nitrogen-Aerated Flotation under Low Alkalinity Conditions

This study investigated the enhanced depression of pyrite and its underlying mechanism through nitrogen-aerated flotation under low alkalinity conditions by means of micro-flotation experiments and various analysis methods, such as X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Results revealed that the effective inhibition of pyrite in air flotation could only be achieved under high alkalinity conditions. Both the formation of dixanthogen and the avoidance of excessive iron oxide/hydroxide formed on pyrite surface were the key to improve the pyrite recovery. Under high alkalinity conditions, surface oxidation of pyrite increased and the formation of dixanthogen was depressed, leading to a reduction in the adsorption of xanthate and the inhibition of pyrite flotation. However, compared with air aeration, the depression of pyrite was strengthened during flotation with nitrogen aeration when pH > 4.2. At pH around 7, the recovery of pyrite was 58.80 % in air flotation, but only 9.35 % in nitrogen flotation. Nitrogen aeration could lower the slurry potential, and suppress the formation of dixanthogen when pH > 6.7. Therefore, pyrite could be effectively inhibited under low alkalinity conditions. The findings of this study offer a new reference for achieving effective flotation separation of polymetallic sulfide ores with suppressed sulfur recovery under low alkalinity conditions. (c) 2024 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.