Proximate Analysis of Coal

To determine moisture content, volatile matter, fixed carbon, and ash content of a given coal sample by proximate analysis (IS 1350 method).

Proximate analysis determines the percentage of four components in coal:

• Moisture (M): Loss in weight on heating at 105°C for 1 hour in air.
• Volatile Matter (VM): Additional loss in weight on heating at 925°C for 7 min in a covered crucible (after M removed).
• Ash (A): Residue after burning at 750°C in air to constant weight.
• Fixed Carbon (FC): FC = 100 – (M + VM + A)

These parameters determine coal rank and quality for industrial use (coking coal, steam coal, etc.).

1. Moisture: Weigh ~1g coal in an open crucible (W₁). Heat at 105°C for 60 min. Cool in desiccator, weigh (W₂). M% = (W₁−W₂)/W₁ × 100.
2. Volatile Matter: Weigh ~1g coal in a covered silica crucible (W₁). Heat at 925°C for exactly 7 min. Cool in desiccator, weigh (W₂). VM% = (W₁−W₂)/W₁ × 100 − M%.
3. Ash: Weigh ~1g coal in an open crucible (W₁). Heat at 750°C in a muffle furnace until constant weight. Cool and weigh (W₂). A% = W₂/W₁ × 100.
4. Fixed Carbon: FC% = 100 − (M% + VM% + A%).
5. Report results on an air-dried basis and as-received basis.

Moisture = ____%, Volatile Matter = ____%, Ash = ____%, Fixed Carbon = ____%. Sum = 100%.

• Coal must be finely ground and uniformly sampled.
• The VM crucible MUST have a tight-fitting lid to prevent air entry.
• All coolings must be done in a desiccator to prevent moisture absorption.
• The muffle furnace temperature must be accurate — use calibrated thermocouple.

• IS 1350 (Part I) – Methods of Test for Coal: Proximate Analysis
• Rattan, S. – Engineering Chemistry