Advancing and receding contact
angles for the air/shale/water system were 42° and 24°,
respectively. A 70 g of mixture of carbonaceous copper
shale (10 g) and quartz (60 g), both with the narrow size
fraction of 40−100 μm, and distilled water were mixed
together and agitated for 2 min in the flotation cell before
adding any reagent. In each test, the air flow rate was
10 L/h and the stirring speed was 1200 r/min. The
experiments were performed under natural pH conditions