Flotation tests Flotation tests were carried out with a XFG5-35 flotation machine with 40 mL effective cell volume and the impeller speed fixed at 1650 r/min. 2.0 g pure mineral was put into a 100.0 mL breaker with 40.0 mL distilled water to clean the surface for 10 min to wipe off the attached oxide by using ultra-sonic cleaner. The treated mineral was washed with distilled water for three times and then transferred into the flotation cell. The pulp pH was adjusted with HCl or NaOH aqueous solution and then agitated for 2 min. After adding the desired amount of reagents, the suspension was agitated for 2 min,and the frother was last added before flotation. The flotation process was conducted for 5 min. The products and tails were weighed separately after filtration and dried and the recovery was calculated.The specific flotation process was shown in Fig. 1 and the recovery was calculated according to the following equation:
R
= m1
m1 +
m2
×
100%
where R represents the pure minerals’ recovery; m1 and m2 are the weight of froth products and prod