OWINGS MILLS, Md. — The Ravens welcomed back a number of key players for this week’s mandatory minicamp, but one veteran who had been practicing throughout the spring was not participating on Tuesday. Attempting to return to the NFL after two serious right hip injuries in two years, tight end Dennis Pitta had taken part in voluntary organized team activity workouts on a limited basis this spring, but he has not been medically cleared to participate in minicamp. Head coach John Harbaugh and others have said throughout offseason that Pitta’s status for the 2015 season will not be determined until later this summer, but Tuesday was a reminder of how far he still has to go to return to action — if it happens at all. Pitta watched Tuesday’s practice from the sideline. “A couple things are going to have to happen for him to play, ultimately,” Harbaugh said. “No. 1, he’s going to have to be cleared by the doctors, and No. 2, he’s going to have to decide he wants to play, because, obviously, there will be some risk involved. The first thing hasn’t happened, yet. He hasn’t been cleared by the doctors. He has been going through