Banca de DEFESA: DAVID DE BARROS GALO

Mine closure in the semi-arid region of Bahia

Keywords: Mine closure; legislation; legacy; mine planning; mine rehabilitation; early closure.

The success of mine closure, and the minimization of its associated risks, depends primarily on the associated regulations and how mining companies plan for closure. Thus, this research was divided into two research papers. In Paper 1, considering the best international practices, an assessment of the mine closure’s legislation was made in the Brazilian federal level and of the current processual flow. Therefore, nine relevant recommendations from the literature were selected to create a regulatory structure of mine closure. The recommendations were classified in satisfies, partially satisfies and does not satisfies, by the authors's professional judgment. The results shows that despite the advances obtained with the recent changes, the Brazilian mine closuring legislation still has inconsistencies, incoherence, gaps and does not meet the requirements from international recommendations. The current legal requirements still do not guarantee the reduction of impacts associated to the mine closure. A new flow was proposed in the mine closure process, and changes to improve the regulatory process of mine closure in Brazil. In Paper 2, considering international best practices recommendations, we developed and tested a procedure to evaluate, during the operational phase, the preparedness of companies to close a mine. Based on the principles of physical stability, chemical stability, socioeconomic transition, and post-mining land use, a weighted checklist containing 69 best practice statements was tested in three operating metal mines in Northeastern Brazil. The best practice statements and their respective weights were submitted to a 12-member expert group. The practices are organized in four assessment areas: (i) mine closure documents, (ii) physical and chemical stability, (iii) costs and financial provisioning, and (iv) community engagement and social transition. In applying the tool, evidence is collected by document review, interviews and site inspections, and evaluated using professional judgement to determine a level of achievement for each group of practices. A preparedness index is then calculated and a preparedness level is obtained. All field-tested mines ranked high for cost and financial provisioning, possibly reflecting they are publicly-owned companies, but ranked in the medium range for the three other assessment areas, indicating a risk of negative legacy. In view of the results presented, mine closure should be a matter of concern for regulators, investors and communities.