Enrichment Mechanisms of Gallium and Indium in No. 9 Coals in Anjialing Mine, Ningwu Coalfield, North China, with a Preliminary Discussion on Their Potential Health Risks

Abstract

To provide a comprehensive insight into the enrichment mechanism of gallium and indium in No. 9 coals, eighteen samples were collected from Anjialing mine, Ningwu Coalfield, Shanxi Province for coal petrological, mineralogical and geochemical analyses. The results suggested that Ga and In enrichment mainly hosted in the top horizons, with average concentration coefficients of 8.99 and 2.73 respectively, compared with the rest of horizons (2.46 for Ga and 1.69 for In). Source apportionment indicated that Ga and In were mainly derived from bauxite of Benxi Formation in Yinshan Oldland, while In could originate from felsic magmatic rocks in Yinshan Oldland as well. In addition, weak oxidation condition, medium to intensive weathering, transgression and input of terrestrial higher plants had positive effects on Ga and In enrichment. With the rapid expansion of emerging electronics manufacturing, Ga and In, of which potential risks on human health were neglected previously, were recently considered as hazardous elements. Therefore, this paper also discussed the potential pathways that these elements threatened human health. We suggested that potential risks on environment and human health caused by Ga and In enrichment in coals and coal-related products should be taken into account besides their economic value.

Separation and Recovery of Valuable Carbon Components and Li/Ga Metals in Coal Gangue by Using a Flotation Flowsheet

“…This may be because Li and Ga are lithophilic elements with a high affinity for oxygen and are easily soluble in silica–aluminum salt melts. 32 This conclusion was consistent with the results of previous analyses.…”

“…As shown in Figure , a 400 μm × 400 μm region of the sample was analyzed, and Li and Ga were found to be closely related to Al and Si, suggesting that Li and Ga predominantly occurred in aluminosilicate minerals. This may be because Li and Ga are lithophilic elements with a high affinity for oxygen and are easily soluble in silica–aluminum salt melts . This conclusion was consistent with the results of previous analyses.…”

Occurrence of harmful elements in the ‘high-aluminium coals' from the Pingshuo mining district, Shanxi Province, China

“…In the process of the utilization in coal, harmful trace elements will enter the atmosphere, water and soil, which will deteriorate local ecological environment and threaten human health (Liu and Liu, 2020). Many researchers focused on health risk assessment on the cohort suffered from chronic exposure to the contamination induced by coal mining and utilization (Huang et al, 2016; White and Shine, 2016, Zhang et al, 2021). Liu and Liu (2020) summarized the impacts of coal dust on miners’ health.…”

“…Although there is no official standard for Li in drinking water, the US Geological Survey suggested a permissible limit of 60 μg/L and a health-based screening level of 10 μg/L (Lindsey et al, 2021). Zhang et al (2021) studied the enrichment mechanisms of Ga and In of No.9 Coal in Anjialing Mine with a preliminary discussion on their potential health risks. It is evident that In and Ga exhibit substantial toxicity in certain occupational scene where indium lung disease has been recognized as a potentially fatal disease caused by the inhalation of indium-containing particles (White and Shine, 2016).…”