Boliden's share jumped on the news, closing 4.7 percent up at 2.23 crowns, having hit a three-month high of 2.24 crowns.A provincial court, the Audiencia Provincial de Sevilla, announced that the lower court's ruling remained in force, Boliden said in a statement.
"The accident was caused by construction deficiencies and flawed conclusions in the preparatory geological studies and hence not by the activities of Boliden Apirsa," the company said, referring to its Spanish subsidiary.
A Boliden Apirsa spokesman said that the appeals court's decision meant the company had once again been cleared of criminal charges.
However, a civil lawsuit remained a possibility, the spokesman said.
The lead-and-zinc mine Los Frailes became the scene of Spain's worst environmental disaster in April 1998 when part of a waste reservoir collapsed, spilling almost seven million cubic metres of toxic waste just outside the Donana National Park, Europe's largest natural reserve.
In the statement, Boliden's Chief Executive Jan Johansson said the new ruling paved the way for Boliden to claim compensation from those who built the dam. (Additional reporting by Chris Brown in Madrid).