BS ISO 587:2020 pdf free.Coal and coke一- Determination of chlorine using Eschka mixture.
BS ISO 587 A known mass of sample is ignited in intimate contact with Eschka mixture in an oxidizing atmosphere to remove combustible matter and to convert the chlorine to alkaline chlorides. These are extracted with nitric acid or water and determined by either the Volhard or the Mohr method, or by potentiometric titration using an lon Selective Electrode (ISE].WARNING -Care should be exercised when handling reagents, many of which are toxic and corrosive.During analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water, or water of equivalent purity.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 (6.4) uniformly with 0,5 g of the Eschka mixture (5.1.1). 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 1It is convenient to weigh out initially 4 g of 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 [6.3) and raise the temperature to 675 °C土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 (6.5) and insert into the muffle furnace at a temperature of 675 °C士25 °C. Maintain this temperature for two hours. Withdraw the crucible and allow to cool.NOTE2 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.BS ISO 587 pdf downlaod.