The Mechanism of Selective Separation of Antimony from Chloride Leachate of Copper Anode Slime

The mechanism of selective separation of antimony from copper anode slime leachate is studied. Density functional theory is used to calculate the unit cell energy, band structure, density of states, number of charge distributions and overlap populations of the SbCl3 hydrolysates SbOCl, Sb3O4Cl and Sb4O5Cl2, and these are studied by infrared spectroscopy. The pathways for formation of SbOCl, Sb3O4Cl and Sb4O5Cl2 in water, ethanol and ethylene glycol systems are clarified. The results show that the energy of the SbOCl unit cell is the lowest, and the structure is more stable. SbOCl exhibits strong electronic localization, weak orbital expansion, and more stability; SbOCl has a wider pseudoenergy gap, and its covalent bonds are stronger than those of Sb3O4Cl and Sb4O5Cl2. Hydrolysis of SbCl3 leads to preferential generation of more stable structures. The charge distribution, the sizes of overlap populations, and the infrared spectra indicate that SbCl3 has been hydrolysed. There are two basic paths for the process of alcoholysis: a water- or alcohol-ionized hydroxyl replaces one chlorine atom in SbCl3 to form an [Sb(OH)Cl2] monomer, and as the degree of hydrolysis increases, the H and Cl atoms are removed to form SbOCl. Conversely, Sb3O4Cl, Sb4O5Cl2 or Sb atoms may be formed an [Sb-OH] monomer generated directly by water- or alcohol-ionised hydroxyl groups, and Cl atoms replace the H atom in the hydroxyl group of the [Sb-OH] monomer to form SbOCl, Sb3O4Cl and Sb4O5Cl2.