Crucible should be pre-baked at 850℃ for an hour or analyzed (without a sample) before loading sample
Samples may be analyzed as air dried
Crush and grind to make the sample size ≤0.212mm(according to different standard)
First burning Temp.:500℃ Keeping Time: 30 min (according to different standard)
Combustion Temp.:815℃ Keeping Time: 60 min.
GB/T 212 ISO 1171 ASTM D3174
1. Weigh to the nearest 0.1mg, the clean, crucible, spread approximately 1g of the sample evenly in the crucible and reweigh. If a silica or porcelain crucible is used, before its initial mass is determined, it should be heated to 815℃ ±10℃, maintained at this temperature for 15mins and then cooled under conditions specified for the actual determination.
2. Insert the crucible in the furnace at room temperature. Raise the furnace temperature evenly to 500℃ over a period of 60 min and hold at this temperature for 30 mins. For brown coals, a holding period of 60mins at 500℃ is necessary.
3. Continue heating to 815℃±10℃ in the same furnace or, alternatively, transfer the crucible to a second furnace, previously heated to 815℃±10℃. Maintain this temperature for at least 60mins. Alternatively for coke, the crucible placed on the plate may be inserted directly in a furnace at 815℃±10℃. Maintain at this temperature for at least 60mins.
4. When the incineration period is complete, remove the crucible from the furnace and allow to cool on a thick metal plate for 10mins. At the end of the 10mins cooling period, transfer the crucible to a desiccator or other closed container without desiccant and allow to cool to room temperature. When cool, weigh to the nearest 0.1mg.
5. If there is any doubt that incineration is incomplete (e.g. unburned carbon particles are visible), reheat at 815℃±10℃ for further 15mins periods until the change in mass does not exceed 1mg.