Why is zinc not extracted from zinc oxide through reduction using CO?

AG° for the conversion of Zn into ZnO is approx. —650 kJ and for the conversion of CO into CO_{2} is approx. -450 kJ, i.e.

For the reaction,

Positive value of AG° shows that the reaction is not feasible. That’s why, CO cannot be used for the reduction of ZnO into Zn.