Effect of Cu(Ⅱ) and Ni(Ⅱ) adsorption on serpentine flotation

The adsorption and activation mechanisms of Cu²⁺ and Ni²⁺ ions on serpentine were investigated through adsorption measurements,pure mineral flotation tests and IR spectra analyses. It is found that the adsorption of Cu²⁺ and Ni²⁺ ions on serpentine agrees with the second order kinetics model,and the isothermal adsorption process correlates well with the Langmuir isotherm model.The adsorption is a spontaneous process,which is caused jointly by physical and chemical functions. The adsorption amount of Cu²⁺ and Ni²⁺ ions on serpentine increases with increasing p H values. Under a weak alkaline condition,serpentine can be activated by Cu²⁺ and Ni²⁺ ions. The active sites can be formed on the surface of serpentine after being reacted with hydroxide and hydroxy complexes of copper and nickel,on which xanthates can be adsorbed to generate copper and nickel xanthates. These hydrophobic products improve the surface hydrophobicity of serpentine and thus activate its flotation.