Release Behavior of Lead and Mineral Transformation Characteristics of Micro-Scale Galena in Different Media

The weathering behavior of galena, as the main lead ore, directly affects the migration and fate of heavy metal Pb in the environment. Weathering environment and time both affect the weathering products of galena. Previous studies have mostly focused on single-factor, short-term, electrochemical and stir experiments, neglecting galena weathering behavior under long-term and conventional experimental conditions. Therefore, through a one-year room-temperature static experiment combined with inductively coupled plasma-mass spectrometry (ICP-MS) and X-ray diffraction (XRD) analysis, the influence of different media on the release behavior of Pb²⁺ in galena and the mineral phase transformation was explored. According to the characteristics of phase diagram and mining area environment of galena, experimental groups for pH, associated mineral (pyrite), oxidant (ferric chloride), and organic acids (acetic acid, citric acid, and humic acid) as well as a pure water control group were set up. The results showed that: ferric chloride addition significantly increased Pb²⁺ release from galena; acetic acid and citric acid promoted Pb²⁺ release; low pH was conducive to Pb²⁺ release; pyrite and humic acid significantly inhibited Pb²⁺ release. Mineral phases changed significantly in the pyrite and ferric chloride groups, yielding well-crystallized secondary minerals—anglesite and cotunnite, respectively. Because the solubility product (K_sp) of cotunnite is much higher than that of galena and anglesite, the Pb element in cotunnite is more likely to enter the solution. Unlike previous studies, the pyrite group did not promote galena dissolution through the galena-pyrite galvanic interaction. In this group, a large amount of anglesite was formed and deposited on the surface of galena, acting as a passivation layer that inhibited the release of Pb²⁺. This study reveals the static dissolution of galena in different media over a long period, addressing the shortcomings of stir experiments in recognizing the mineral passivation phenomenon. It provides a scientific basis for pollution prevention, control, and remediation strategies in mining areas. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202504170095.