ISO 1171

Coal and Coke — Determination of Ash

Applicability: Applies to coal, coke, lignite, anthracite, and other solid mineral fuels for determination of the incombustible mineral residue remaining after controlled combustion. Used internationally in quality control, trade specifications, and contractual testing as an equivalent to national standards such as ASTM D3174. The method is not applicable to biofuels or biomass-derived fuels, for which ISO 18122 applies for ash determination.

Purpose: Determines ash content gravimetrically by igniting and burning an analysis sample in an open crucible at 815 ± 10°C until constant mass is achieved. The residual mass, expressed as a percentage of the air-dried sample, represents the incombustible mineral content of the fuel. Ash content is used to calculate effective heating value, quantify combustion residue for disposal planning, assess fuel quality for contractual specification compliance, and design combustion and handling systems where excessive ash causes fouling, slagging, or abrasive wear.