Assay Step 1 Method A

The coal sample was weighed in a dry, clean platter (1.2) of known weight and weighed to 500 g (weighed to 1 g) and the coal sample in the pan was evenly spread. The platter with the coal sample was placed in a drying box (1.1) pre-blasted and heated to 105-110°C, and the bituminous coal was dried for 2 to 2.5 hours under constant air blowing conditions, and the anthracite coal was dried for 3 to 3.5 hours. Remove the tray from the oven and weigh it while hot. An inspection test is then carried out for 30 min each time until the reduction of the coal sample does not exceed 1 g or the weight increases. In the latter case, the one-time weight before weight gain should be used as the calculation basis.

Note: The blast is started 3 to 5 minutes before placing the plate called the coal sample in the drying oven.

2 Method B

The coal sample was weighed in a dry, clean platter (1.2) of known weight and weighed to 500 g (weighed to 1 g) and the coal sample in the pan was evenly spread.

The platter filled with coal samples was placed in a drying box (1.1) which had been pre-blasted and heated to 150-160°C. At 145±5°C and continuous air blast, bituminous coal was dried for 30 min, anthracite coal was dried for 1 h, and lignite was used. Dry 1.5h. Remove the tray from the oven and weigh it while hot. An inspection test is then carried out for 15 min each time until the reduction of the coal sample does not exceed 1 g or the weight increases. In the latter case, the one-time weight before weight gain should be used as the calculation basis.

3 Method C

Weigh 10-12 g of coal sample (weighed to 0.01 g) with a known dry, clean weighing bottle (1.5) and gently shake the coal sample to make it flat. Open the weighing bottle cap, put the weighing bottle with coal sample into a drying box that has been pre-blasted and heated to 145±5° C., dry the bituminous coal for 30 min under continuously blowing conditions, dry the lignite for 45 min, and dry the anthracite for 60 min. Then, the weighing bottle was taken out of the drying box, immediately covered with a cover, cooled in the air for about 5 minutes, transferred to a dryer (1.4), cooled to room temperature (about 30 minutes) and weighed again. An inspection test is then carried out for 15 min each time until the reduction of the coal sample does not exceed 0.01 g or the weight increases. In the latter case, the one-time weight before weight gain should be used as the calculation basis.