Challenges to access and safeguard mineral resources for society: A case study of kaolin in Portugal

摘要

Present and future demands of minerals require enlightened land use policies and practices that consider geological resources as a whole, anticipating potential conflicts and proposing/monitoring solutions to ensure the access to mineral resources and their responsible use. The use of a multi-criteria methodology able to balance the geological knowledge (grounding the identification of mineral resources) with the economic, environmental and social dimensions implicated in their current or foreseen exploitation may provide the way needed to conciliate the foremost goals of any mining planning and land-use planning exercises. The safeguarding of kaolin resources was the selected case study because: (i) the current and future access to these resources are confronted with different types of conflicts with other land uses; (ii) the exploitation and transformation of kaolin are increasingly important to the regional and national economy, generating as well numerous jobs all over the added value chain and attracting foreign investment; and (iii) the historical environmental liabilities related to old ex-ploitations that still grounds strong apprehensions by the public in general. In this study, the Portuguese kaolin resources were represented by 136 specific tracts, 110 being classified as of "public importance" after considering criteria supporting the geological knowledge dimension. Preceded by a structured point densification scheme, an interpolation process was performed, within the kriging formalism. The resulting map delimited a total area of approximate to 342 km(2) (0.4% of Portugal mainland) whose intrinsic value should support a safeguarding decision on the current and future access to kaolin resources in Portugal mainland. The 29 active and productive mines were further classified based on the economic, environmental and social dimensions and distributed within the three levels of priority for safeguarding, as proposed by the methodology. The results achieved are underestimated mostly due to several limitations of the available databases. Nevertheless, this remains a powerful potential tool to be applied for kaolin mineral resources safeguarding in two distinct and coexisting ways: (1) for future access, ensuring the supply of forthcoming generations and avoiding the sterilisation of tracts of "public importance"; and (2) for the short-medium term access, assigning specific areas to exploitation activities, regularly supplying the industry and markets. This methodology has been successfully applied to other minerals (e.g. Mateus et al., 2017), but additional efforts must be made to extend the assessment to other raw materials.