Size distribution, chemical composition, and emission factors of particulate matter from metallurgical processes

Abstract

The metallurgical industry is an important anthropogenic source of atmospheric particulate matter and associated heavy metals. However, the size distribution, chemical profiles, and potential toxic burdens of particulate matter emitted from metallurgical sources remain insufficiently characterized. In this study, a dilution sampling system was used to collect particulate matter in four size fractions from nine typical metallurgical processes in China, covering zinc, copper, aluminum, tin, lead, and iron/steel smelting. A total of 51 chemical species, including inorganic elements, water-soluble ions, and carbonaceous components, were systematically characterized, and size-resolved emission factors were calculated. The results showed that pyrometallurgical and hydrometallurgical zinc smelting emitted the highest total particulate matter (TPM) concentrations, reaching 27.2 and 26.5 mg/m³, respectively. Their corresponding TPM emission factors were 2.24 × 10³ and 704 g/t. Metallurgical particulate emissions were dominated by PM_1–2.5 and PM₁, with PM_2.5/PM₁₀ ratios ranging from 0.59 to 0.86. The chemical composition exhibited pronounced size-dependent differences and strong process specificity. Crustal elements contributed more prominently to particles larger than PM_2.5, whereas water-soluble inorganic ions, organic carbon, and heavy metals were increasingly enriched in PM_1–2.5 and PM₁. Notably, tin smelting showed a clear decoupling between TPM emission intensity and PM₁-bound risk-related metal burden, indicating that conventional control strategies based solely on total particle mass may overlook fine-mode metal emission priorities.

Graphical abstract

Keywords

Metallurgical industry / Particulate matter / Dilution sampling / Emission factors / Heavy metals

Highlight

	● Size-resolved PM profiles were obtained for nine metallurgical processes.
	● Metallurgical particles were dominated by PM2.5, with process-dependent size shifts.
	● Chemical profiles showed strong process specificity across particle size fractions.
	● PM1-bound metal burdens revealed control priorities overlooked by TPM-based metrics.

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