The depressant-free flotation separation of Cu/Zn sulfide minerals with an environmentally friendly triazine-thiol collector

The depressant-free flotation separation of chalcopyrite from sphalerite in the lower alkaline (pH<10) environment will contribute to reduce carbon emission and benefit the recovery of precious metal minerals. However, it is almost impossible for traditional collectors such as xanthates due to their weak selectivity for chalcopyrite against sphalerite. In this paper, a novel triazine-thiol collector, 2-diethylamine-4-hydroxy-1,3,5-triazine-6-thiol (DEHTT), was first introduced in flotation separation of chalcopyrite from sphalerite. The micro-flotation results elucidated that in the absence of depressants, the recoveries of chalcopyrite and sphalerite from their mixture with 2.0 x 10(-6) mol/L DEHTT at pH 9.45 (Na2CO3 as regulator) were 91.83 % and 28.84 %, respectively, while those with sodium isobutyl xanthate (SIBX) were 96.11 % and 78.00 % under the same conditions. In situ AFM and contact angle exhibited that DEHTT assembled on chalcopyrite surface to form lots of aggregates which increased its hydrophobicity, while an insignificant change of sphalerite surface was observed. FTIR, zeta-potential and XPS explored that DEHTT chemisorbed the Cu sites of chalcopyrite surface through its S or O atoms. The specific flotation affinity of DEHTT to chalcopyrite might contribute the cleaner recovery of copper sulfide ores with the lower carbon emission.