  The existence of K giant stars with high Li abundance continues to challenge
the standard theory of stellar evolution. All recent extensive surveys in the
Galaxy show the same result: about 1 % of the mainly normal slow rotating K
giants are Li rich. We explore here a model with two scenarios based on the
important relation of Li-rich and Li-poor K giants with IR excesses. In this
model, all K giant stars suffer a rapid enrichment and depletion of Li inducing
the formation and ejection of circumstellar shells. The observational detection
of these shells will not only validate this model, but also will give important
hints on the mechanism of Li enrichment of these stars.
