The work of Colombian artist Doris Salcedo explores pain, trauma and loss, while creating space for individual and collective mourning. She has staged events and exhibitions in many of the world’s leading galleries and spaces. She talks to Spanish journalist and writer Jesús Ruiz Mantilla about her latest work, Palimpsesto, commissioned by Spain’s Reina Sofía Museum, which is in homage to migrants who have drowned while crossing the Mediterranean.