GB/T 17664-2024Charcoal (English PDF)

5.1 Determination of moisture

5.1.1 Principle A specimen of a certain mass is dried at a specified temperature to constant mass, the percentage of the mass lost relative to the original mass of the specimen is determined.

5.1.2 Instruments and equipment

5.1.2.1 Electric thermostatic drying oven. room temperature ~ 200 °C, temperature control accuracy ±1 °C.

5.1.2.2 Balance. sensitivity

0.01 g.

5.1.2.3 Weighing bottle.

5.1.3 Test procedure Perform two tests in parallel. Crush the specimen into particles smaller than 10 mm, mix quickly, weigh 10 g ~ 20 g of the specimen (accurate to

0.01

g) into a pre-dried and weighed weighing bottle, place it in a drying oven preheated to 105 °C, dry for 2 h ~ 3 h, remove the bottle, place it in a desiccator, cool to room temperature (approximately 30 min), and weigh. Then perform check tests, each lasting 30 min, until the specimen mass loss is less than

0.01 g or the mass increases. In the latter case, the mass before the increase shall be used as the basis for calculation.

5.1.4 Test data processing The moisture is expressed as W, as a percentage (%), and calculated according to formula (1). where. W - the moisture content, %; m - the mass of the specimen, in grams (g); m1 - the mass of the dried specimen, in grams (g). The calculation result is expressed as the arithmetic mean of two parallel tests, and the relative deviation shall not exceed 0.5 %. The results are expressed to one decimal place.

5.2 Determination of ash

5.2.1 Principle A dried specimen of a certain mass is ignited and ashed at a specified temperature to constant mass (weighed after cooling), the percentage of the mass of the residue relative to the original mass of the specimen is determined.

5.2.2 Instruments and equipment

5.2.2.1 High-temperature electric furnace. room temperature ~ 1000 °C, temperature control accuracy ±5 °C.

5.2.2.2 Electric thermostatic drying oven. room temperature ~ 200 °C, temperature control accuracy ±1 °C.

5.2.2.3 Porcelain crucible with a lid. volume 30 mL.

5.2.2.4 Analytical balance. sensitivity 0.0001 g.

5.2.3 Samples Take at least 10 g of sample to grind, pass all through a

0.25 mm sieve, place it in an oven at 105 °C to dry to constant mass, and place it in a desiccator to cool to room temperature.

5.2.4 Test procedure

5.2.4.1 Place a 30 mL porcelain crucible with a lid in a high-temperature electric furnace, ignite at (800 ± 20) °C to constant mass, cool in air for 5 min, place the crucible in a desiccator, and weigh after cooling to room temperature (accurate to 0.0001 g).

5.2.4.2 Weigh 1 g (accurate to 0.0001

g) of the dried specimen and place it in a 30 mL porcelain crucible that has been ignited to constant mass; place the crucible and specimen together in a high-temperature electric furnace at a temperature not exceeding 300 °C; open the crucible lid, close the furnace door, gradually raise the furnace temperature to 800 °C, and ignite it at (800 ± 20) °C to constant mass. Remove the crucible and place it on a porcelain plate, cover the crucible with the lid, cool it in air for about 5 min, place it in a desiccator, cool it to room temperature (about 30 min), and weigh (accurate to 0.0001 g).

5.2.5 Test data processing The ash is expressed as A, as a percentage (%), and calculated according to formula (2). where. A - the ash content, %; m3 - the mass of the ash and the crucible, in grams (g); m2 - the mass of the crucible, in grams (g); mA - the mass of the specimen, in grams (g). The calculation result is expressed as the arithmetic mean of two parallel tests, and the relative deviation shall not be greater than 0.2 %. The results are expressed to one decimal place.

5.3 Determination of volatile matter

5.3.1 Principle A dried specimen of a certain mass is heated at 850 °C in the absence of air for 7 min, the percentage of the mass lost relative to the original mass of the specimen is determined.

5.3.2 Instruments and equipment

5.3.2.1 Special crucible for volatile matter. made of porcelain; specific parameters are shown in Figure 1.

5.3.2.2 High-temperature electric furnace. room temperature ~ 1000 °C, temperature control accuracy ±5 °C.

5.3.2.3 Crucible rack. made of porcelain, capable of accommodating 4 crucibles in parallel, with the bottom of the crucibles on the rack 10 mm ~ 15 mm from the furnace bottom.

5.3.2.4 Stopwatch or timer.

5.3.2.5 Analytical balance. sensitivity 0.0001 g.

5.3.3 Samples Take at least 10 g of sample to grind, pass all through a

0.25 mm sieve, place it in an oven at 105 °C to dry to constant mass, and place it in a desiccator to cool to room temperature.