Characteristics and threats of particulate matter from zinc electrolysis manufacturing facilities

Electrolysis process in hydrometallurgy could generate particulate matter (PM) that contains hazardous inorganic acids and heavy metals. This PM generally poses more health risks than conventional atmospheric PM. Here, we investigated the PM characteristics in two representative zinc hydrometallurgy manufacturing facilities in China. The concentrations of the total suspended particles (TSP), PM < 10 μm (PM10), and PM < 2.5 μm (PM2.5) were found to exceed the relevant standards of China and the WHO. Sulfuric acid, sulfate ion, and heavy metal elements predominated in the components of PM. Maximum concentrations of sulfuric acid mist in TSP and PM10 were 6.78 and 14.4 times higher than the respective occupational exposure limits (OELs), respectively. High heavy metal concentrations could lead to carcinogenic and non-carcinogenic risks. Furthermore, with the newly developed source apportionment method, the dominant source of PM and components in PM was found to be the zinc electrolysis process. Some heavy metals, such as Pb, As, Sb, and Cr, presented higher enrichment in PM2.5 due to the intrinsic electrolysis process (e.g., the intrinsic enrichment factors of As, Sb, and Cr > 103). The results suggest that effective cleaner production technologies should be developed in hydrometallurgical industries and stringent regulations on PM, heavy metals, and sulfuric acid mist should be imposed to reduce the health risk in metal electrolysis workplaces.