GB/T 212-2008Proximate analysis of coal (English PDF)

11722.1999 Solid mineral fuels - Hard coal - Determination of moisture in the

general analysis test sample by drying in nitrogen, ISO 1171.1997 Solid mineral

fuels - Determination of ash, ISO 562.1998 Hard coal and coke - Determination

of volatile matter. The degree of consistency with the above international

standards is not equivalent. The main differences are as follows.

- ADD the industrial analysis method for coal water mixture;

- ADD the air drying method for moisture determination;

- ADD the fast ashing method for ash determination;

- In the volatile content determination procedure, SPECIFY the raising

temperature and time as (900 ± 10) °C, 3 min;

- USE the appendix to add the microwave drying method for moisture

determination.

This standard replaces GB/T 212-2001 "Proximate analysis of coal", GB/T

15334-1994 "Determination of moisture in coal - Microwave drying method",

GB/T 18856.7-2002 "Test methods for quality of coal water mixture - Part 7.

Proximate analysis of coal water mixture".

The main changes of this standard as compared with GB/T 212-2001 are as

follows.

- ADD the industrial analysis method for coal water mixture (Chapter 8 of

this edition);

- ADD the "Determination of moisture in coal - Microwave drying method"

(Appendix A of this edition).

Appendix A and Appendix B of this standard are normative appendixes.

This standard was proposed by China Coal Industry Association.

This standard shall be under the jurisdiction of the National Coal

Standardization Technical Committee.

Drafting organizations of this standard. Coal Analysis Laboratory of China Coal

Research Institute, Yunnan Coalfield Geological Survey Company 143 Team.

3.1 Method A (nitrogen drying method)

3.1.1 Method summary

Weigh a certain amount of coal sample for general analysis test; put them in a

drying box at (105 ~ 110) °C; dry them in a dry nitrogen stream to a constant

mass. Then calculate the mass fraction of water based on the mass loss of the

coal sample.

3.1.2 Reagent

3.1.3 Instruments and equipment

3.1.3.1 Small space drying cabinet. The cabinet is tight, has a small free space,

has gas inlet and outlet, is equipped with an automatic temperature control

device, which can maintain the temperature within the range of (105 ~ 110) °C.

3.1.3.4 Drying tower. 250 ml capacity, containing desiccant.

3.1.3.5 Flowmeter. The range is (100 ~ 1000) mL/min.

3.1.3.6 Analytical balance. Sensitivity is 0.1 mg.

3.1.4 Test procedure

3.1.4.1 In a pre-dried and weighed weighing bottle, weigh (1 ± 0.1) g of coal

sample for general analysis test which has a particle size of less than 0.2 mm,

accurate to 0.0002 g; spread it flatly in the weighing bottle.

3.2 Method B (air drying method)

3.2.1 Method summary

Weigh a certain amount of coal sample for general analysis test; place them in

blast drying oven at (105 ~ 110) °C; dry them in an air stream to a constant

mass. The mass fraction of water is calculated from the mass loss of the coal

sample.

3.2.2 Instrumentation

3.2.3 Test procedure

3.2.3.1 In a pre-dried and weighed weighing bottle, weigh (1 ± 0.1) g of the coal

sample for general analysis test which has a particle size of less than 0.2 mm,

accurate to 0.0002 g; flatly spread it in the weighing bottle.

3.2.3.2 Open the lid of the weighing bottle and put it in a drying box (3.2.2.1)

that has been blasted and heated to (105 ~ 110) °C. Under the condition of

constant blowing, bituminous coal is dried for 1 h, whilst anthracite is dried for

1.5 h.

3.3 Calculation of results

Calculate the moisture content of the coal sample for general analysis test

according to formula (1).

4.1 Slow ashing method

4.1.1 Method summary

Weigh a certain amount of coal sample for general analytical test; put it in a

muffle furnace; heat it to (815 ± 10) °C at a certain rate; ash and burn to a

constant mass. The mass fraction of the residue to the mass of the coal sample

is taken as the ash content of the coal sample.

4.1.2 Instrumentation

4.1.2.3 Dryer. Same as 3.1.3.3.

4.1.2.4 Analytical balance. Same as 3.1.3.6.

4.1.2.5 Heat-resistant porcelain plate or asbestos plate.

4.1.3 Test procedure

4.1.3.1 In an ash dish pre-burned to a constant mass, weigh (1 ± 0.1) g of coal

sample for general analysis test with a particle size of less than 0.2 mm,

accurate to 0.0002 g; spread evenly and flatly in an ash dish so that its mass

per square centimeter does not exceed 0.15 g.

4.2 Fast ashing method

This part includes two fast ashing methods. method A and method B.

4.2.1 Method A

4.2.1.1 Method summary

Place the ash dish containing the coal sample on the conveyor belt of the fast

ash tester which is heated to (815 ± 10) °C in advance. The coal sample is

automatically fed into the instrument to completely ash and then sent out. The

mass fraction of the residue mass to the mass of the coal sample is taken as

the ash content of the coal sample.

4.2.1.2 Special instrument. Fast ash tester (see Figure B.1 in Appendix B).

4.2.1.3 Test procedure

4.2.2 Method B

4.2.2.1 Method summary

The ash dish containing the coal sample is gradually sent from the outside of

the furnace into a muffle furnace which was preheated to (815 ± 10) °C and

ashed and burned to a constant mass. The mass fraction of the residue to the

mass of the coal sample is taken as the ash content of the coal sample.

4.2.2.2 Instruments and equipment. Same as 4.1.2.

4.2.2.3 Test procedure

4.2.2.3.1 In an ash dish pre-burned to a constant mass, weigh (1 ± 0.1) g of

coal sample for general analysis test with a particle size of less than 0.2 mm,

accurate to 0.0002 g. Uniformly and flatly spread it in an ash dish so that the

mass per square centimeter does not exceed 0.15 g. Dispense the ash dishes

containing coal samples on heat-resistant porcelain plates or asbestos plates

in advance.

5.1 Method summary

Weigh a certain amount of coal sample for general analysis test. Place it in a

porcelain crucible with a lid. Heat it at (900 ± 10) °C for 7 minutes in the absence

of air. The mass fraction of the reduced mass accounting for the mass of the

coal sample minus the moisture content of this coal sample to obtain the volatile

content of the coal sample.

5.2 Instrumentation

5.2.1 Volatile crucible. A ceramic crucible with a tightly fitted lid, the shape and

size of which are as shown in Figure 3.The total mass of the crucible is (15 ~

20) g.

In millimeters

Figure 3 -- Volatile crucible

5.2.2 Muffle furnace. It is equipped with a pyrometer and temperature

adjustment device, which can maintain the temperature at (900 ± 10) °C and

have a sufficient (900 ± 5) °C constant temperature zone.

5.2.4 Crucible holder clamp (see Figure 5).

Figure 5 -- Crucible holder clamp

5.2.5 Dryer. Same as 3.1.3.3.

5.2.6 Analytical balance. Same as 3.1.3.6.

5.2.7 Cake press. Spiral or lever cake press, capable of pressing coal cakes

with a diameter of about 10 mm.

5.2.8 Stopwatch.

5.3 Test procedure

5.6 Precision of volatile determination

The precision of volatile determination is as specified in Table 3.

7.1 Dry ash-free volatile matter is converted according to formulas (5) to (7).

When the mass fraction of carbonate carbon dioxide in the coal sample for

general analysis test is (2 ~ 12) %, then.

8.1 Preparation of analysis samples

8.2 Determination of moisture in coal water mixture

8.2.1 Method summary

Weigh a certain amount of evenly stirred coal water mixture specimen; put it in

a drying box at (105 ~ 110) °C; dry it in air flow to constant mass. Then calculate

the mass fraction of moisture in the coal water mixture based on the mass loss

of the coal water mixture.

8.2.2 Instrumentation

Same as 3.2.2.

8.2.3 Test procedure

8.2.4 Calculation of results

Calculate the moisture of coal water mixture according to formula (11).

8.2.5 Precision of moisture measurement

The repeatability limit of moisture determination for coal water mixture is as

specified in Table 4.

8.3 Determination of moisture in dried coal water mixture specimen

Determine the moisture of the dry sample of coal water mixture in accordance

with Chapter 3 of this standard.

8.4 Determination of ash in coal water mixture

8.4.1 Determination of ash in dried coal water mixture specimen

Determine the air-dried base ash content of the dried coal water mixture

specimen in accordance with the provisions of Chapter 4 of this standard.

8.5 Determination of volatile matter in coal water mixture

8.5.1 Determination of volatile matter in dry specimen of coal water

mixture

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