ISO 334-2020 pdf download.Coal and coke一Determination of total sulfur- Esch ka method.
8.3 IgnitIon
8.3.1 For coal
Place the charged crucible (and any others up to the limit of the muffle furnace capacity) in the cold muffle furnace (6.3) and raise the temperature to 800 C a 2% 5C in about 1 h. maintaining this temperature for at least a further 1.5 h Withdraw the crucible (or crucibles) and allow to cool.
NOTE The cracking of porcelain cn.ciblcscan be prevented if they are slowly cooled by iissertkm in supports of light porous Iirebrick on removal from the muffle furnace
8.3Z For coke
Place the charged crucible (or crucibles) on the cold insulating flat plate (6.5) and insert into the mufllc furnace (6.3) at a temperature of 900 C * 25 C. maintaining this temper.lture for at least a further 1,5 h. Withdraw the crucible (or cruclbles) and allow to cool. See Note In &3.1.
8.4 Recovering the resIdue
Transfer the ignited mixture from the crucible to a 400 ml beaker containing 25 ml to 30 ml of water. If unburnt particles are present. the determination shall be stopped and the test repeated. Wash the crucible thoroughly with about 54) ml of hot water and add the washings to the contents of the beaker.
8.5 Ixtractlon
Place a watch glass on the beaker and then, while tilting the witch glass, carefully add vnough hydrochloric acid (5.2) to dissolve the solid matter (17 ml will normally be required), warming the contents of the beaker to effect solution. Boil for 5 mm to expel carbon dioxide and filter, collecting the filtrate in a 400 ml conical beaker.
NOTE A medium-textured. doubly acul-wached filter paper or a filter-paper pad is recommended for speed of tiltratliaL
To prepare the filter-paper pad, shake doubly acid-washed filter-paper clippings, in pieces with areas of approximately 1 cm2, with water In a bottle until the paper Is thoroughly dIsrntegrated. Place a porcelain fIlter cone of 25 mm In a 75 mm funnel, close the stem of the funnel with a finger, and add water until the cone Is immersed and the funnel stem Is full. Shake, onto the cone. sufficient paper pulp to form a pad 5 mm thick, and level it with a flat-ended g1ass rod. Allow the excess water to drain away by removing the finger from the stem and as drainage ceases, lightly tamp the pad around the edges with the glass rod, A final wash with water renders the filter ready for use
Wash the filter with live 20 ml portions of hot water
Add two or three drops of the methyl red indlcatoi’ solution (5,5) to the combined filtrate and washings. and then cautiously add the ammonia solution (5,6) until the colour of the Indicator changes and a trace of precipitate Is formed. Md cilough hydroehluflc acid (5.2) to lust redissoiw the precipitate and then add I ml in excess,
8.6 PrecIpitation olbanum sulfate
After extractk)n, dilut, the solution, if necessary. to approximately 200 ml and cover the beaker containing the solution with a watch glass. Heat the covered beaker until the solution boils and then reduce the hearing slightly until ebullition of the solution ceases. Then add 10 ml of the cold barium chloride solutIon (5.4) from a pipette with a delivery time of approximately 20 s so that the barium chloride solution falls into the centre of the hor solution while it is being agitated. Keep the solution iust below boiling point for 30 mm.ISO 334 pdf download.