Coal gangue has dual
attributes of waste residue and resources.
Clarifying the release characteristics of harmful trace elements from
the coal gangue can provide a theoretical basis for environmental
impact and resource utilization. In this study, the characteristics
of harmful trace elements released from coal gangue in Xinjiang during
dynamic leaching and static immersion experiments were determined
using proximate analysis, X-ray powder diffraction (XRD), X-ray fluorescence
spectrometry (XRF), and inductively coupled plasma mass spectrometry
(ICP-MS). The results show that (1) the higher the content of harmful
trace elements in coal gangue and the greater the concentration coefficient
(CC), the greater the release of elements in dynamic leaching and
static immersion experiments. The mode of occurrence of trace elements
in the coal gangue determines their transport and release. Elements
are associated not only with moisture but also with minerals, such
as clays, sulfides, and carbonates, which are readily soluble in water.
(2) The release of harmful trace elements was inversely proportional
to time in the dynamic leaching experiments, and the main reason for
the reduction in element release during the late leaching period was
the adsorption effect of clay minerals. In the dynamic leaching experiment,
harmful trace elements in the surrounding environment continued to
accumulate, and static immersion experiments in water showed that
harmful trace elements gradually reached dynamic equilibrium. The
concentration of most elements in the late stage of the static immersion
experiment was lower than that in the early stage, indicating that
the environmental hazards of dynamic leaching were greater than those
of the static immersion of coal gangue in Xinjiang.