2. Experimental
2.1. Materials
Chemical grade ethyl xanthate and butyl xanthate were provided by the Zhuzhou Flotation Reagents Factory in Hunan Province.
Sodium humate was obtained from the Pingxiang Dewei Humic Acid Chemical Factory of Pingxiang City (Jiangxi Province),
and elemental analyzes indicated that the sodium humate contained 51.30% C, 3.74% H, 2.38% N and 42.58% O.
Fig. 1 illustrates the molecular structure of humic acid. As shown in the figure, sodium humate contains many functional groups, including carboxyls,
phenols, amino groups, quinones and condensed aromatic
rings, which play an important role in the chemical properties of
sodium humate.