Based on the excavations of two metallurgical furnaces from the Catarpe Túnel site (San Pedro de Atacama) in operation during the Late Period (A.D. 1400-1536), and oriented to the production of metallic copper, we discuss the role of woody fuel in the development of this technology in the hyper-arid context of the Atacama Desert. Our study focuses on the analysis of anthracological and carpological material, together with the analysis of the depositional characteristics of combustion events and preliminary ethnobotanical information. As a result, we propose the reconstruction of a phase of the operational chain of copper metallurgy, composed of the handling and use of woody fuel, as well as the identification of possible areas of activity developed in the structures. With this, we propose a comprehensive methodological strategy, focusing on aspects such as the recording and recovery of this type of structures with anthracological potential, which is not usually considered within the general archaeological excavation activities, which in turn is applicable to combustion structures in general, contributing to the understanding of the activities surrounding the handling and use of plant fuel.