GB/T 47597-2026Waste chemicals - Determination methods for loss on drying and loss on ignition (English PDF)

5.1 Drying under normal pressure

5.1.1 Principle Weigh a certain amount of sample, place it in an electric thermostatic drying oven, dry it to constant weight, and calculate the drying loss.

5.1.2 Instruments and Equipment

5.1.2.1 Electric thermostatic drying oven. The temperature can be controlled at 105 °C±2 °C.

5.1.2.2 Dryer. Built-in desiccant.

5.1.3.1 Weigh 10 g to 50 g of the sample, accurate to

0.01 g, and place it in a pre-dried electric thermostatic drying oven at 105 °C ± 2 °C. Inside a heavy, flat weighing bottle or a covered container.

5.1.3.2 Open the container lid and place it in an electric thermostatic drying oven preheated to 105 °C±2 °C for 4 h.

5.1.3.3 Remove from the electric thermostatic drying oven, place in a desiccator to cool for 30 minutes, and then weigh.

5.1.3.4 Repeat the above steps for 1 hour each time until constant weight is achieved (the absolute difference between two consecutive weighings is no greater than

0.02 g).

5.1.3.5 For samples with high moisture content (greater than 60%), the samples should be dried for 12 hours first, and then repeated drying should be performed at 1-hour intervals. Dry and weigh.

5.2 Reduced pressure drying

5.2.1 Principle Weigh a certain amount of sample, place it in a vacuum drying oven, dry it to constant weight, and calculate the drying loss.

5.2.2 Instruments and Equipment Vacuum drying oven. meets the requirements of GB/T 29251.

5.2.3.1 Weigh 10 g to 50 g of the sample, accurate to

0.01 g, and place it in a flat weighing bottle or container that has been pre-dried at 105 °C ± 2 °C and has reached constant weight. Inside a covered container.

5.2.3.2 Based on the known properties of the waste chemicals, select a suitable temperature of 40 °C~70 °C as the vacuum drying temperature, referring to the saturated steam temperature of water. (See Appendix A) Select a suitable pressure lower than the saturated vapor pressure of water at the corresponding temperature, record the selected temperature and pressure values, and explain them. reason.

5.2.3.3 Place the weighed sample into the vacuum drying oven, close the oven door and vent valve, maintain a suitable pressure inside the vacuum drying oven, and heat simultaneously. Bring the chamber to the required temperature (not higher than 70 °C), and after 4 hours, turn off the power, open the vent valve, and wait for the pressure to return to normal before opening the chamber door.

5.2.3.4 After removing it, immediately cover it and place it in a desiccator (5.1.2.2) to cool for 30 minutes before weighing.

5.2.3.5 Repeat the above steps for 1 hour each time until constant weight is achieved (the absolute difference between two consecutive weighings is no greater than

0.02 g).

5.2.3.6 For samples that cannot reach constant weight through the above test steps, set a drying time of not less than 4 hours according to the material properties, and record the results. Reasons for choosing conditions.

5.3 Experimental Data Processing Loss on drying, expressed as a mass fraction wLOD, is calculated according to formula (1).

6.2 Instruments and Equipment

6.2.1 High-temperature furnace. The temperature can be controlled at (600±25)°C~(1050±25)°C.

6.2.2 Crucible. 50 mL, with lid, made of high temperature and corrosion resistant material.

6.2.3 Dryer. Built-in desiccant.

6.2.4 Test sieve. phi200×502/

0.9 GB/T 6003.1-2022.

6.3 Test Procedure

6.3.1 Crush or grind the pre-dried sample, and if necessary, pass it through a test sieve.

6.3.2 Based on the known properties of the main components of the waste chemicals, select a suitable temperature of 600°C~1050°C as the incineration temperature, and record the selected temperature. Determine the conditions and explain the reasons.

6.3.3 Weigh 1 g to 5 g of the sample treated in 6.3.1, accurate to 0.0001 g, and place it in a high-temperature furnace at the selected ignition temperature as described in 6.3.2. It is heated in a crucible to constant weight.

6.3.4 Samples with high organic content should be carbonized on an electric furnace before being placed in a high-temperature furnace for burning.

6.3.5 Spread the sample evenly in the constant-weight crucible, place the crucible in a high-temperature furnace, raise the temperature to the set ignition temperature, ignite for 4 hours, and then stop heating. After cooling slightly, use crucible tongs to remove the crucible and place it in a desiccator. After cooling to room temperature, weigh it.

6.3.6 Repeat the above steps, igniting for 1 hour each time, until constant weight is achieved (the absolute difference between two consecutive weighings is no greater than

0.002 g).

6.3.7 For samples that cannot achieve constant weight through the above test steps, set an ignition time of not less than 4 hours according to the material properties, and record it accurately. Explain the reasons for the selection criteria.

6.4 Experimental Data Processing Loss on ignition, expressed as mass fraction wLOI, is calculated according to formula (2).