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Flotation separation of cervantite (Sb2O4) from quartz was investigated using dodecylamine (DDA) as a collector. Experiments were conducted on single minerals and on a synthetic mixture of quartz and cervantite. Flotation separation mechanisms were investigated using the zeta potential technique, solution chemistry principles, density functional calculations and Fourier Transform Infrared (FT-IR) spectroscopy. The results indicated that DDA, primarily in the form of molecules, exhibited excellent performance in flotation of cervantite and quartz at pH 10.5. The adsorption energy of the DDA molecules on the cervantite surface was greater than the adsorption energy of water molecules, while the adsorption energy of DDA on the quartz surface was less than the adsorption energy of water molecules. DDA molecules can be adsorbed on the quartz surface to a certain extent, but it was difficult for the same molecule to be adsorbed on the cervantite surface in the pulp. This resulted in flotation of quartz. DDA molecules were adsorbed on quartz not only through physical adsorption but also by hydrogen bonding. However, cervantite could not be floated at pH 10.5 since adsorption of DDA molecules occurred through weak physical bonds on cervantite. (Authors.), Flotation separation of cervantite (Sb2O4) from quartz was investigated using dodecylamine (DDA) as a collector. Experiments were conducted on single minerals and on a synthetic mixture of quartz and cervantite. Flotation separation mechanisms were investigated using the zeta potential technique, solution chemistry principles, density functional calculations and Fourier Transform Infrared (FT-IR) spectroscopy. The results indicated that DDA, primarily in the form of molecules, exhibited excellent performance in flotation of cervantite and quartz at pH 10.5. The adsorption energy of the DDA molecules on the cervantite surface was greater than the adsorption energy of water molecules, while the adsorption energy of DDA on the quartz surface was less than the adsorption energy of water molecules. DDA molecules can be adsorbed on the quartz surface to a certain extent, but it was difficult for the same molecule to be adsorbed on the cervantite surface in the pulp. This resulted in flotation of quartz. DDA molecules were adsorbed on quartz not only through physical adsorption but also by hydrogen bonding. However, cervantite could not be floated at pH 10.5 since adsorption of DDA molecules occurred through weak physical bonds on cervantite. (Authors.)

The surface physicochemical properties of cervantite Sb2O4 are similar to the gangue minerals, so it is difficult to achieve the flotation separation of cervantite from them. In order to improve the floatability of cervantite, the phase and floatability changes of cervantite were investigated by the sulphidisation roasting with the element sulphur in reducing atmosphere and flotation tests. Cervantite did not float while using isoamyl xanthate as collector. But its floatability improved greatly by the sulphidisation roasting with sulphur, and a sulphide layer of Sb2S3 is found to be the key component which causes the hydrophobicity of sulphidised cervantite. The flotation recovery of sulphidised cervantite increased from 5% to 95% while the molar ratio of S:Sb changed from 0 to 1.5. In other words, the floatability of the sulphidised cervantite increased with the increased thickness of sulphide layer. However, the sulphide layer thickness depended on the additive amount of sulphur, roasting time and temperature. In the process of sulphidisation roasting, sulphur changed first from solid to liquid state, then the liquid sulphur reacted with the surface of cervantite, and experienced the following change of Sb2O4 to Sb2O3(O)/Sb2O3(C) to Sb2S3. In addition, the Sb2S3 phase will further react with Sb2O4 if there is lack of sulphur in the sulphidisation roasting system., The surface physicochemical properties of cervantite Sb2O4 are similar to the gangue minerals, so it is difficult to achieve the flotation separation of cervantite from them. In order to improve the floatability of cervantite, the phase and floatability changes of cervantite were investigated by the sulphidisation roasting with the element sulphur in reducing atmosphere and flotation tests. Cervantite did not float while using isoamyl xanthate as collector. But its floatability improved greatly by the sulphidisation roasting with sulphur, and a sulphide layer of Sb2S3 is found to be the key component which causes the hydrophobicity of sulphidised cervantite. The flotation recovery of sulphidised cervantite increased from 5% to 95% while the molar ratio of S:Sb changed from 0 to 1.5. In other words, the floatability of the sulphidised cervantite increased with the increased thickness of sulphide layer. However, the sulphide layer thickness depended on the additive amount of sulphur, roasting time and temperature. In the process of sulphidisation roasting, sulphur changed first from solid to liquid state, then the liquid sulphur reacted with the surface of cervantite, and experienced the following change of Sb2O4 to Sb2O3(O)/Sb2O3(C) to Sb2S3. In addition, the Sb2S3 phase will further react with Sb2O4 if there is lack of sulphur in the sulphidisation roasting system.