BS ISO 562:2010 pdf download – Hard coal and coke — Determination of volatile matter
1 Scope
This International Standard specifies a method of determining the volatile matter of hard coal and of coke. lt isnot applicable to brown coals and lignites.
2 Normative references
The following referenced documents are indispensable for the application of this document.For datedreferences,only the edition cited applies. For undated references, the latest edition of the referenceddocument (including any amendments) applies.
ISo 687, Solid mineral fuels — Coke —Determination of moisture in the general analysis test sample
ISO11722,Solid mineral fuels —Hard coal—Determination of moisture in the general analysis test sampleby drying in nitrogen
A portion of the sample is heated out of contact with air at 900 °C for 7 min. The percentage mass fraction ofvolatile matter is calculated from the loss in mass of the test portion after deducting the loss in mass due tomoisture.
4Reagents and materials
4.1Cyclohexane, of recognized analytical grade.
5 Apparatus
5.1 Furnace,heated by electricity,in which a zone of uniform temperature of 900 “C±5 °C can bemaintained.
lt may be of the stop-ended type or fitted at the back with a flue approximately 25 mm in diameter and150 mm long (see Figure 1).
lt is important for furnaces with flues that the furnace door seal well. The flue should not reach far out of theoven and should be fitted with a butterfly valve to restrict airflow through the furnace.
lts heat capacity shall be such that,with an initial temperature of 9o0 °C, the temperature is regained within4 min after insertion of a cold stand and its crucibles. The temperature is measured with a thermocouple (5.2).
Normally, the furnace is designed specifically either for multiple determinations using a number of crucibles inone stand or for receiving one crucible and its stand. In the first case, the zone of uniform temperature shall beat least 160 mm x 100 mm; in the latter case, a zone with a diameter of 40 mm is sufficient.
A position for the crucible stand shall be chosen within the zone of uniform temperature and this position shall be used for all determinations. The temperature of 900 °C shall be attained as closely as possible with a specified tolerance of ±5 °C in order to compensate for inherent errors in the temperature measurement and lack of uniformity in the temperature distribution.
5.2 Thermocouple, unsheathed, of wire no thicker than 1 mm. It should be long enough to reach the centre of the underside of each crucible when placed in the zone of uniform temperature on being inserted through the front or rear of the furnace. The thermojunction shall be placed midway between the base of the crucible in its stand and the floor of the furnace. If the stand holds more than one crucible, the temperature under each crucible shall be checked in the same manner. If desired, a sheathed thermocouple may be permanently installed in the furnace (see Figure 1) with its thermojunction as close as possible to the centre of the zone of uniform temperature; in this case furnace temperature readings shall be correlated at frequent intervals with those of the unsheathed thermocouple, which is thus inserted only when necessary. NOTE The temperature/electromotive force relationship of a thermojunction maintained at elevated temperatures gradually changes with time.
5.3 Crucible, cylindrical, with a well-fitting lid, both of fused silica. The crucible with lid shall have a mass between 10 g and 14 g and dimensions approximating to those shown in Figure 2. The fit of the lid on the crucible is critical to the determination and a lid shall be selected to match the crucible so that the horizontal clearance between them is no greater than 0,5 mm. After selection, the crucible and the lid shall be ground together to give smooth surfaces and then be given a common distinguishing mark. When performing multiple determinations on highly swelling coals, it can be necessary to use taller crucibles. These may be up to 45 mm in height without affecting the determined volatile matter, provided that the specified rate of temperature recovery be maintained.
5.4 Crucible stand, on which the crucible is placed in the furnace, such that the appropriate rate of heating can be achieved. For example, it may consist of the following: a) for single determinations, a ring of heat-resistant steel wire as shown in Figure 3
a) with ceramic discs, 25 mm in diameter and 2 mm thick, resting on the inner projection of its legs; or b) for multiple determinations, a tray of heat-resistant steel wire as shown in Figure 3
b), of appropriate size, with ceramic plates 2 mm thick supporting the crucibles. 5.5 Balance, capable of reading to the nearest 0,1 mg.