China Reference Materials Meaning – Certificate of Certified Reference Material Ash fusibility – Shandong Institute of Metallurgical Science

This certified reference material is made from carefully selected raw coal. The coal was air dried, reduced in size to <0.2mm and ignited at 815℃ to constant mass and homogenized, then packaged in to individual bottled units.

  The homogeneity test was done on the bottled units by determination of the sulfur in ash and FT under the reducing atmosphere. The minimum mass of sample taken for analysis is 0.05g(sulfur) and about 0.15g(FT). Variance analysis showed that the variability among different bottles was not significantly different from the variability between replicate determinations.

Here, the reducing atmosphere is obtained by introducing into the furnace the mixture gases of (50±5)% CO₂ and (50±5)% H₂ (in the most tests) or by sealing in the furnace the proper ratio of graphite and anthracite (in a few tests); the oxidizing atmosphere is obtained with air circulates freely through the furnace.

The certification analyses were performed according to the Chinese National Standard GB/T219-2008 by several qualified laboratories.

The certified value is expressed as X_T±U，were X_T is the mean value and U is the expanded uncertainty(95% confidence level).

The preparation of samples, the statistical analysis and overall direction and coordination of the technical measurements leading to certification were by China National Coal Quality Supervision and Testing Center, China Coal Research Institute.

This certified reference material is stable at long time. China National Coal Quality Supervision and Test Center will monitor the change of certified value regularly and inform the users if any significant change is observed.

1) This certified reference material is packed in a plastic bottle, 30g/ bottle.

2) The bottle containing material should be kept tightly stopped and stored in cold and dry place, and opened only when necessary.

3) This certified reference material is mainly used in the examination of the testing

atmosphere and the estimation of the test result. The testing atmosphere is correct if  the differences between test result and certified value of ST, HT, FT are not over 40℃; otherwise, the testing atmosphere is not correct, and some adjustments are necessary.

4) This certified reference material is not applicable in the identification of the deviation of furnace temperature, the users should be sure the furnace temperature has been controlled correctly before the testing.