Río Tinto Explosives Factory Historical milestone · Guardo, Alto Carrión, Palencia The Explosivos Río Tinto factory operated in Guardo between 1942 and 2008 and turned the town into a chemical as well as a mining centre; its closure marked the end of the industrial cycle that had sustained the town. 1942-2008 Photo: Alejandro Polanco (CC BY 3.0) What to see and do in Guardo