lowsulfur

Low sulfur, written here as lowsulfur, is a descriptor applied to materials whose sulfur content has been reduced relative to standard grades. It is used in several industries, most notably in fuels, coal, and metallurgy, where lower sulfur helps meet environmental targets and improve processing performance.

In fuels such as diesel and heating oil, lowsulfur indicates sulfur content kept to very low levels. Regulations in many regions set maximum sulfur contents in fuels to limit sulfur dioxide emissions from combustion. In practice, achieving lowsulfur fuels often involves hydrotreating and other desulfurization steps in refineries, with sulfur recovered as elemental sulfur or sulfuric acid. The resulting fuels are commonly marketed as ultra-low-sulfur diesel or similar labels, typically targeting tens of parts per million by weight.

In coal and related feedstocks, lowsulfur coal contains less sulfur than standard coal, reducing sulfur oxide emissions when burned and lowering corrosion and fouling in plants and equipment.

In metallurgy and steelmaking, low sulfur iron or ore reduces sulfide inclusion and improves ductility and toughness. Desulfurization can occur during smelting or through ore processing and flux techniques.

Measurement and regulation: sulfur content is measured by X-ray fluorescence, combustion methods, or other analytical techniques and reported in parts per million (ppm) or percent by weight. Standards and thresholds vary by jurisdiction but generally trend toward lower sulfur levels to meet air-quality and refinery-efficiency goals.