Role of decaethoxylated stearylamine in the selective flotation of hornblende and siderite: An experimental and molecular dynamics simulation study

• DSA exhibits excellent collection performance for hornblende instead of siderite. • Hornblende adsorbs DSA strongly by electrostatic attraction and hydrogen bonding. • Large adsorption amounts of DSA improve the hydrophobicity of hornblende. • Hornblende is effectively removed from dolomite with DSA. • A sorption model of DSA for removing hornblende from siderite is proposed. This investigation focused on the collection performance and sorption mechanisms of decaethoxylated stearylamine (DSA) applied as a new high-selectivity hornblende collector, to further extend the use of DSA for efficiently recovering siderite from hornblende. The collecting ability of DSA to both minerals was explored via a series of flotation experiments. Flotation results illustrated that in comparison with DDA, DSA displayed an excellent collection performance for the hornblende flotation, whereas it hardly collected siderite. With 0.18 mM DSA, siderite could be efficiently separated from hornblende at pH 6.30 through reverse flotation. The selective collection mechanisms of DSA for hornblende were uncovered via surface wettability, X-ray photoelectron spectroscopy (XPS), surface electrical properties, infrared spectrum (IR) characterizations, and molecular dynamics (MD) simulations. Contact angle detection indicated that DSA strengthened the surface hydrophobicity of hornblende instead of siderite, which promoted the strong collection of hornblende. Besides, surface electrical detection and IR analyses suggested that the intense DSA sorption toward the hornblende was due to the combination of electrostatic adsorption and hydrogen bonding interaction. It was demonstrated by XPS results that larger amounts of DSA were adsorbed onto hornblende than siderite, and the O sites of hornblende were involved in electrostatic attraction and hydrogen bonding interaction. Furthermore, MD simulations further revealed that compared with siderite, the intense adsorption of DSA on the hornblende was due to the hydrogen bond and electrostatic interactions between its amino group and the hornblende surface, as evidenced by a much smaller interaction distance and very negative electrostatic energy. Therefore, DSA can be utilized as an efficient collector for collecting hornblende to achieve the desiliconization of the siderite flotation.