BS ISO 587:2020 pdf download.Coal and coke — Determination of chlorine using Eschka mixture.
6.5 Flat plate, 6 mm thick, of silica or other suitable refractory material, which fits easily into the muffle furnace (3).
6.6 Potentiometrlc titration assembly, equipped with a chloride ion selective electrode and double junction reference electrode.
7 Preparation of the test sample
The sample shall be the general analysis test sample, prepared to a nominal top size of 212 lIm by the preparation procedures specified in ISO 13909-4 orISOJ.8283.
The sample should be brought in moisture equilibrium with the laboratory atmosphere by exposure in a thin layer on a tray. Exposure time shall be kept to a minimum.
The sample shall be thoroughly mixed for at least 1 mm immediately before analysis, preferably by mechanical means.
lithe results are to be calculated other than on an “air-dried” basis (see Clause 9), then, after weighing the test portion, determine the moisture content using a further portion of the test sample by the method specified in ISO 687. ISO 5068-2 or ISO 11722.
8 Procedure
8.1 Combustion
Weigh, to the nearest 0,1 mg, a test portion of approximately 1 g, for samples with an expected chlorine content greater than 0,1 %, or 2 g for samples with a lower expected chlorine content.
Cover the bottom of the crucible (fi,4) uniformly with 0,5 g of the Eschka mixture (5J.Jj. Thoroughly mix the test portion with 2,5 g of the Eschka mixture in a suitable container. Transfer the mixture to the crucible, level the contents by gently tapping the crucible on the bench and cover uniformly with a further 1 g of the Eschka mixture.
NOTE I It is convenient to weigh out initially 4 gal the Eschka mixture and to extract the portions required for the bottom and top layers using a small glass tube, calibrated for each batch of Eschka mixture, to deliver 0,5 g and 1 g portions without weighing. The bottom layer of Eschka mixture reduces attack on silica and porcelain surfaces so that extraction of chlorine with hot water is complete even when the surface deteriorates.
For coals, place the charged crucible in the cold muffle furnace 3) and raise the temperature to 675 °C ± 25 °C in about one hour. Maintain this temperature for a further two hours. Withdraw the crucible and allow to cool.
For coke, place the charged crucible on the cold flat plate () and insert into the muffle furnace at a temperature of 675 °C ± 25 °C, Maintain this temperature for two hours. Withdraw the crucible and allow to cool.
NOTE 2 Cracking of the porcelain crucibles is prevented if they are cooled slowly by insertion into supports constructed from a light, porous refractory material after removal from the muffle furnace.
8.2 Completion
Complete the determination by either the Volhard (81.1), the Mohr (8.2.2) or the ISE method (8.2.3).BS ISO 587 pdf download.