Besides oxygen, nitrogen and inert gases, the air alsocontains carbonic acid gas and water vapor, these air compositions have a certain effect on the ore flotation of flotation machine, and the specific performance are showed in the following three aspects:


1. Minerals show a fresh surface after being crushed, when the fresh surface meet water, it will happen hydration, manifested as hydrophilic. But when the gas adsorption to mineral surfaces, can weaken the hydration, resulting in preliminary hydrophobic of fresh surface.


2. The effects of gas for mineral surface are selective, oxygen has larger effect on the mineral surface among them.


3. The influence of oxygen is available for the preliminary hydrophobic of sulfide ore. But if the time is too long, it will cause the mineral surface chang into hydrophilic. But when gas adsorption condition is appropriate, it will cause the hydrophobic of mineral surface, even without adding flotation agent, it can carry on flotating (such as dry pulverized coal). And only after the preliminary effect of oxygen, galena can happen a reaction with xanthate which lead to the galena floating.