Improving fine malachite particle recovery: Triethanolamine enhances surface sulfidization and xanthate adsorption

Copper oxide minerals often require fine grinding to liberate them from gangue minerals, but overgrinding during industrial milling can result in their loss during flotation. This study investigates the use of triethanolamine (TEA) as a cost-effective and low-polluting modifier to enhance the recovery of fine malachite. The flotation tests of an oxide copper ore indicated that TEA modification increased the total copper recovery of concentrate by 17.69 % and the copper recovery in the fraction with particle sizes <30 μm by 6.59 %. The modified fine malachite (<38 μm) achieved a maximum recovery of over 82 % in terms of malachite micro-flotation. Zeta potential measurements and adsorption tests confirmed that TEA increased the surface potential and the number of active sites, enhancing the S ion chemisorption. Solution chemistry, X-ray photoelectron spectroscopy, and scanning electron microscopy analysis revealed that the predominant Cu − TEA complex was Cu(TEA)(OH)⁺, which exhibited high reactivity with S ions and increased the amounts of Cu(I) sulfides and polysulfides in the form of flakes and micro-globular precipitates on the fine malachite surfaces. These precipitates increased the distribution density of hydrophobic Cu(I)-xanthate upon xanthate addition, based on a microscopic Fourier-transform infrared spectroscopy investigation. The findings suggest that TEA exhibits significant potential for enhancing the surface sulfidization and xanthate flotation of fine copper oxide ores for industrial applications.