Occurrence state and enrichment mechanism of cobalt associated with vanadium-titanium magnetite in the Damiao deposit, Chengde

Cobalt is considered as an important strategic metal and is widely used in batteries, alloys and other fields. The Damiao district of Chengde vanadium-titanium magnetite deposit is the main deposit in the most important vanadium-titanium magnetite mineralization area in China, and it is accompanied by the critical metals such as cobalt, which has significant economic and strategic value. Previous studies have been conducted in the fields of geology, geochemistry and isotopic geochronology. However, research on the occurrence state and enrichment mechanisms of associated metals in vanadium-titanium magnetite deposit has yet to be undertaken. This study focuses on ores of different structures from the Dongdawa vanadium-titanium magnetite deposit. Based on petrography, Advanced Mineral Identification and Characterization System (AMICS) mineral analysis, Electron Probe Micro-Analysis (EPMA) and Laser ablation inductively coupled plasma mass spectrometry analysis (LA-ICP-MS) were conducted to investigate the occurrence state of cobalt, as well as to elucidate the mechanisms of cobalt enrichment. No independent cobalt minerals have been observed. Cobalt mainly substitutes for Fe in the crystal lattice of pyrite through isomorphism. The cobalt content in pyrite varies among different types of ores, ranked from highest to lowest as follows: dense massive-dense disseminated chloritization Fe-Ti ores (0.73%), carbonatization and chloritization Fe-Ti-P ores (0.31%), disseminated ores chloritization Fe-Ti ores (0.21%). The origin of cobalt-containing pyrite in the Dongdawa deposit is considered as hydrothermal. Sulfur-containing hydrothermal fluids with high temperature and high pH promoted the enrichment of cobalt.