Froth stabilities and iron ore flotation of collectors 3-dodecyloxypropanamine and 3-tetradecyloxypropylamine: An experimental and molecular dynamics study

Abstract

In the mineral processing industry, froth properties are essential. To separate iron minerals and gangue minerals in a flotation mill, froths that are both too stable and fragile are useless for obtaining qualified concentrate in the mining industry. We tried to develop two collectors to adjust the froth stability during flotation. In this study, we first researched the froth stabilities of collectors 3-dodecyloxypropanamine (DOPA) and 3-tetradecyloxypropylamine (TOPA). Contact angle measurements and surface tension measurements were used to research the hydrophobicity of DOPA and TOPA and to predict its flotation performance. Froth stability measurements and molecular dynamics (MD) were conducted to investigate the froth properties of DOPA, TOPA, and dodecyl amine (DDA), and to reveal the froth mechanism of flotation. The film interface models were built using software Materials Studio 2017 software, and MD was used to simulate the flotation system. The interaction formation energy (IFE) was calculated to compare the froth film strength of the three collectors. Surface tension measurements indicated that DOPA and TOPA were more robust collectors in decreasing water surface tension than DDA. The froth stability measurements showed that the DDA froth was the most stable of the froths with the three collectors, consistent with the MD simulations of the foam models. Furthermore, the adsorption configuration of the interface of DOPA or TOPA and solution was drawn, and the numbers and the average length of different kinds of hydrogen bonds of the three configurations were counted and calculated. We can infer that the hydrogen bonds between the O atom of water and the —NH2 of DOPA or TOPA are not the main force of their IFE, and the main force is van der Waals force. Finally, the micro-flotation of the artificial mixed mineral was conducted to verify the previous prediction of DOPA and TOPA. This paper provided a new case to adjust the flotation performance by developing a collector and predicting its froth stability.