PRELIMINARY METHODOLOGICAL GUIDE FOR A COMPREHENSIVE ANALYSIS OF SITES INTENDED FOR DISPOSAL OF MINING WASTE IN MEXICO

In Mexico, the mining activity began over 500 years ago. The main extraction methods which have been used are: amalgamation with mercury, silver-gold electrolysis, acid lixiviation, sulfur flotation, zinc electrolysis and biolixiviation. Today it is known that the tailings that contain metal sulfide minerals can originate acid mine drainage (AMD). The country has a wide variety of metal sulfide deposits, being Taxco (Guerrero); Tizapa (State of Mexico); La Valenciana (Guanajuato); Zimapan, Molango, Mineral del Monte (Hidalgo); Nacozari, La Caridad, Cananea (Sonora); and Santa Barbara (Chihuahua), the most studied with environmental purposes today. Despite the efforts of different research groups, there is not a general outline on how to develop strategies for remediation. So in this study, a preliminary analysis of the current status of these sites, and the research conducted was made to integrate a methodological guide to help make environmental studies at these sites. It was noted that, despite this, the Mexican legislation on hazardous waste disposal, characterization and management of tailings, emerged only in the first decade of the current century. Therefore, Mexican researchers have had to use international methods based on: a) distribution of heavy metals in water and sediments; b) origin, mobility, toxicity and treatment of certain heavy metal or metalloid; c) tailings capacity to generate AMD; d) hydrogeochemistry and its relation to mineralogy and geochemistry of the deposits adjacent to water bodies; e) simulation of tailings leaching under climatic conditions to determine the chemical reactions occurring; f) population exposure to metals and metalloids. Moreover, studies about remediation possibilities have focused on: a) simulating laboratory scale wetland to test the efficiency of water treatment; b) phytoremediation strategies, as plants absorbing heavy metals; c) dry covers. This preliminary methodological guide proposes: a) to apply national regulation; b) weathering testing laboratory scale; c) the use of biofilms, geomembranes, among others; d) to conduct studies in the surrounding population to identify possible risk of adverse effects on health, by drinking contaminated water or inhalation of particles transported by wind.