Application of depletion attraction in mineral flotation: II. Effects of depletant concentration

Authors: KIM, GAHEE - Chonbuk National University; CHOI, JUNHYUN - Chonbuk National University; CHOI, SOWON - Chonbuk National University; KIM, KYUHAN - Korean Advanced Institute Of Science And Technology (KAIST); HAN, YOSEP - Chonbuk National University; Bradford, Scott; CHOI, SIYOUNG - Korean Advanced Institute Of Science And Technology (KAIST); KIM, HYUNJUNG - Chonbuk National University

Submitted to: Minerals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2018
Publication Date: 10/14/2018
Citation: Kim, G., Choi, J., Choi, S., Kim, K., Han, Y., Bradford, S.A., Choi, S.Q., Kim, H. 2018. Application of depletion attraction in mineral flotation: II. Effects of depletant concentration. Minerals. 8(10):450. https://doi.org/10.3390/min8100450.
DOI: https://doi.org/10.3390/min8100450

Interpretive Summary: A companion paper theoretically demonstrated that osmotic interaction can control colloid association with air bubbles under certain solution chemistry conditions. Experimental research was conducted to validate this theoretical finding. Results were generally consistent with predicted behavior and demonstrated that the solution chemistry can be optimized to maximize colloid association with air bubbles and mineral recovery. This research has important implications for maximizing mineral recovery, and will therefore be of interest to scientists, engineers, and businesses associated with the mining industry. Results also demonstrate that mineral recovery can be obtained in a more environmentally sustainable manner, and this should be of interest to government, health officials, and concerned citizens.

Technical Abstract: Along with the accompanying theory article, we experimentally investigate the effect of the depletion attraction force on the flotation of malachite. While varying the concentration of the depletion agent (polyethylene glycol), three different systems are studied: pure malachite, pure silica and a 1:1 mass ratio of malachite and silica binary system. We find that the recovery increases significantly as the concentration of the depletion reagents increases for all three systems. However, the recovery suddenly decreases in a certain concentration range, which corresponds to the onset of the decreased surface tension when high concentrations of the depletion agent are used. The decreased surface tension of the air/water interface suggests that the recovery rate is lowered due to the adsorption of the depletion agent to the bubble surface, acting as a polymer brush. We also perform experiments in the presence of a small amount of a collector, sodium oleate. An extremely small amount of the collector (10-10–10-5 M) leads to the increase in the overall recovery, which eventually reaches nearly 100 percent. Nevertheless, the grade worsens as the depletant provides the force to silica particles as well as target malachite particles.