RESCUE TEAMS WORKED Tuesday to free 10 miners trapped underground by a coal mine explosion near the Mongolian capital of Ulan Bator that killed 12 miners and injured at least 30, news reports said. . . . LEBANON'S NEW AMBASSADOR to the Vatican Monday invited Pope John Paul II to visit Lebanon soon and said all the Lebanese would welcome him "in a climate of unity and restored peace." . . . A TEENAGER CONVINCTED of hurling rocks at passing motorists on the Capital Beltway last May has been sentenced to 38 1/2 years in prison.