(General session) Environment / Mineral processing

[2501-08-05] Investigation of collectorless flotation and additive roasting conditions for the recovery of copper from copper sulfide ore

○Bekhzod Mirzo Gayratov^{1[Student presentation: Doctoral course]}, Bobur Gayratov¹, Labone Godirilwe¹, Sanghee Jeon¹, Atsushi Shibayama¹ (1. Akita University)

司会：三木　一（九州大学）

Keywords:sulfide ore, collectorless flotation, chalcopyrite, additive roasting, copper recovery

Copper sulfide ores often contain silica and sulfur-rich gangue minerals, complicating flotation and mineral separation. However, these challenges can be addressed using collectorless flotation, which leverages the natural floatability of chalcopyrite (CuFeS₂) and the hydrophilicity of silica. Pyrite (FeS₂), the main sulfur-bearing gangue, can also be effectively depressed under these conditions, reducing sulfur and iron contamination and improving concentrate quality. Chalcopyrite’s floatability is enhanced by air exposure and pre-aeration of the pulp, achieving high copper recovery and grade. However, due to its refractory nature and strong crystal structure, further copper extraction is difficult. Additive roasting is a promising pre-treatment that modifies mineral surfaces and enhances copper recovery during leaching, overcoming challenges posed by passivating layers that hinder direct leaching.This study investigates a combined approach using collectorless flotation followed by additive roasting and leaching to recover copper from chalcopyrite-rich ore. The ore, containing quartz and pyrite, underwent flotation without collectors, achieving 94.5% copper recovery and a concentrate grade of 7.12% Cu from an initial 0.94%. This concentrate was used in roasting tests with additives like KCl and NaOH under various conditions.Roasting at 600 °C for 1 hour followed by leaching in 0.1 M sulfuric acid at 25 °C yielded copper dissolution of 97% with KCl (1:0.1) and 96.5% with NaOH (1:0.05), while keeping iron dissolution below 5%. NaOH proved particularly effective, offering faster reaction kinetics and better environmental performance.