GB/T 479-2016Determination of plastometric indices of bituminous coal (English PDF)

1 Scope

China's national method for the plastometric indices of bituminous coal - the Sapozhnikov test, which measures what a coal does in the narrow band of temperature where it softens, becomes plastic and then resolidifies into coke. It is one of the two or three determinations on which a coking blend is actually built, because a coal that does not pass through a plastic stage will not bond the blend, and one that swells too much in it will damage the oven wall. The standard specifies the method for determining the plastometric indices of bituminous coal: the maximum thickness of the plastic layer, the final contraction, and the shape of the volume curve that records the movement of the charge throughout the heating. It applies to bituminous coals. A weighed charge is packed into a standard coal cup and heated from below at a controlled rate so that a plastic layer forms and travels upward through the charge; a probe is lowered at intervals to find the upper and lower boundaries of that layer, and a recorder traces the movement of the load plate against time, from which the contraction and the character of the volume curve are read. The determination is unusually dependent on technique, which is why the standard runs to thirty pages and six annexes: the packing of the cup and the asbestos gasket that seals it, the heating schedule and its tolerance, the probing, the cleaning of the cup between tests, and the removal of the coke button all affect the result, and the standard gives each of them, together with a normative annex on discriminating the technical characteristics of the coke produced and a test record sheet. Issued on 13 December 2016 and in force since 1 July 2017, it replaces GB/T 479-2000.

This Standard specifies the terms and definitions, method summary, reagents and materials, instruments and equipment, coal samples, test preparation, test procedures, result expression, method precision and test report for the plastometric indices of bituminous coal. This Standard is applicable to the bituminous coal.

2 Normative references

The following documents are essential to the application of this document. For dated references, only the editions with the dates indicated are applicable to this document. For undated references, only the latest editions (including all the amendments) are applicable to this document.

GB 474 Method for preparation of coal sample

GB/T 483 General rules for analytical and testing methods of coal

3 Terms and definitions

For the purposes of this document, the terms and definitions defined in GB/T 483 and the following ones apply. For ease of use, some of the terms and definitions in GB/T 483 are repeatedly listed below.

3.1 Plastometric indices Indices for characterizing the plasticity of bituminous coal proposed by Sapozhnikov, expressed in the maximum thickness of plastic layer, value of Y, the final contraction value (plastometric shrinkage), value of X, etc.

3.2 Maximum thickness of plastic layer The maximum distance between the curves of the layers plotted at each point on the upper and lower layers of the colloid, which is measured in the determination of the plastometric indices of bituminous coal.

3.3 Volume curve of plastic layer The curve on the upper layer of the colloid, changing with the temperature, which is recorded in the determination of the plastometric indices of bituminous coal.

4 Method summary

PUT a certain amount of coal sample into a coal cup. PLACE the coal cup in a special electric furnace. Then, PERFORM one-sided heating at a predetermined heating rate. Correspondingly, coal sample forms three isothermal layers of semi-coke layer, plastic layer and un-softened coal sample layer.

5 Reagents and materials

5.1 Paper tube. On a thin steel rod, cigarette paper is made into a paper tube with a diameter of 2.5mm to 3mm and a height of about 60mm by adhesion. When installing the coal cup, INSERT the steel rod into the paper tube. FOLD the paper tube at the bottom for about 2mm.

5.2 Filter paper strip. qualitative filter paper in strips, about 60mm wide and 190mm to 200mm long.

5.4 Volume curve recording paper. Standard calculation paper (millimeter coordinate paper) is used as the volume curve recording paper, whose

5.5 Certified reference material for the plastometric indices of bituminous coal.

5.6 Dry abrasive cloth. brown corundum abrasive, with a particle size of P80,

7 Coal sample

7.1 The coal samples for the determination of plastometric indices shall be prepared according to GB 474 to a particle size of not less than 3mm.

7.2 The samples that reach air-dried status shall be stored in a ground-glass stoppered flask or other closed containers. KEEP in a cool place.

8 Test preparation

8.1 Cleaning the coal cups The residual coke breeze on the coal cups, thermocouple wells and pressure plates shall be manually cleaned up with a piece of adhesive cloth (5.6), and may also be removed by using the mechanical method of Annex D. Each blowhole on the bottom of the cup and the pressure plate shall be smooth. There shall be no foreign matter in the thermocouple wells.

9 Test procedures

9.1 When the above preparation is completed, TURN on the switch of the programmable temperature controller.

9.2 If using a drum to record the volume curve, in case of temperature reaching 250°C, ADJUST the recording pen point to contact the recording drum. FIX its position.

9.3 For general coal samples, the measurement begins a few minutes after the plastic layer descends on the volume curve, and stops when the temperature rises to about 650°C.

9.6 According to the volume curve shape recorded by the drum and the characteristics of colloids, the frequencies for measuring the upper and lower plastic layers shall be determined as follows:

9.7 When the temperature reaches 730°C, the test is over. ADJUST the recording pen to move it away from the drum. TURN the power off. REMOVE the weight(s). COOL the instrument.

9.8 When the determination of the plastic layer is completed, the upper brickwork must be completely cooled or replaced for the next test.