316 FROM WASTE ROCK TO SOIL REGENERATION: THE REMINERALIZER OF SERRA NORTE MINE, CARAJÁS – PA, BRAZIL *D.A. Rossi1, R. Kwitko-Ribeiro2, M. Assis1, E. Martins3, M. Ferraz¹ 1Technical Mining Services (VALE S.A.) (*Presenting author: debora.rossi@vale.com) 2 Exploration and Mineral Process (VALE S.A.) 3 Embrapa Cerrados ABSTRACT In 2024, Vale launched its Circular Mining Program, designed to maximize natural resource efficiency and reduce the environmental impacts associated with mining activities. The program consolidated more than 150 initiatives focused on tailings reuse and the development of new circular solutions, including the beneficiation and reapplication of waste rocks. Among these initiatives, the Serra Norte Remineralizer project stands out for transforming basalticcomposition waste rocks into a natural fertilizer, creating value for agriculture while reinforcing the company’s sustainability commitments. In the Carajás Mineral Province (CMP), basalts, diabase dikes, and gabbros—collectively referred to as mafic rocks—are widespread. These igneous rocks occur either as volcanic units, forming lava flow layers at the base (Parauapebas Formation) and the top (Igarapé Cigarra Formation) of the banded iron formation, or as younger intrusive bodies such as diabase and gabbro dikes and sills. Petrographic and geochemical analyses were performed on samples collected from mining quarries and drill cores, primarily in the Serra Norte mine. QEMSCAN® was employed as a petrographic tool, delivering highresolution textural, mineralogical, and elemental distribution data. The results revealed significant contents of biotite, chlorite, and K-feldspar, indicating extensive hydrothermal alteration of variable intensity and predominantly potassic character. Chlorite is the dominant silicate in the fresh mafic rock and the primary carrier of Al, Fe, and Mg. Actinolite and epidote account for most of the Ca partitioning, complemented by plagioclase, scapolite, and calcite. Calcite, the main carbonate mineral identified, contributes more than half of the Ca content in several samples. Potassium feldspar is the main K bearing phase, although phyllosilicates— biotite and muscovite—hold on average 40% of the K, and may locally contain up to 90%, releasing the nutrient more rapidly. The concentrations of CaO, MgO, K₂O, free silica (quartz), and contaminant elements (Cd, Pb, As, and Hg) determined in the fresh mafic rock meet the requirements for registration as a soil remineralizer with the Brazilian Ministry of Agriculture, and Livestock (MAPA). Agronomic efficiency tests also demonstrate positive results, showing that the material increases soil pH and promotes soil regeneration, reinforcing its potential as an effective soil remineralizer. KEYWORDS
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