Sulfur is a common element found in coal. It is present in varying amounts depending on the type of coal and the location where it was mined. When coal is burned for energy, sulfur can be released into the atmosphere as sulfur dioxide (SO2). This can contribute to acid rain and air pollution, which can have negative impacts on the environment and human health.
In many countries, regulations have been put in place to limit the amount of sulfur that can be emitted from coal-fired power plants. This has led to the development and implementation of technologies to capture sulfur before it is released into the atmosphere. These technologies can include flue gas desulfurization systems and coal washing techniques.
Low sulfur coal is also available and is often preferred for use in power generation due to its lower environmental impact. However, the use of low sulfur coal can also result in higher costs, which can be a challenge for some power plants and industries.
Determination of Sulfur in Coal By Eschka’s Mixture Method
Apparatus
Oven, Muffle furnace, beaker, Conical Flask, Funnel, Glass Rod, Butter paper, Desiccator
Regent
- Eschka’s Mixture,
- Conc. HCL
- Methyl Red Indicator
- Liquor Ammonia
- 10 % Barium Chloride
- Whatman filter paper 41
- Whatman filter paper 42
Procedure:
- Take 0.5 gm. of Eschka’s mixture in a silica crucible.
- Take one butter paper and weigh 2.5 gm. of Eschka’s mixture on it.
- Take 1.0 gram of coal on the same butter paper and mix well.
- Pour the above material above the 0.5 gm. of Eschka’s mixture in the silica crucible.
- Again weigh 1 gm of Eschka’s mixture on the butter paper and put it on silica crucible.
- Ignite it at 800 Deg. C for one and half hours in muffle furnace.
- Remove the crucible from furnace and wash the residue with DM water. (Discard it in case of any unburnt carbon present).
- Add 17 ml of concentrated hydrochloric acid.
- Filter with Whatman filter paper no. 41.
- Wash the undissolved particles and pour in to DM water.
- Take the filtrate and add methyl red. Solution will become reddish.
- Add liquor ammonia up to color changes to whitish yellow.
- Add sufficient HCL to redissolve the precipitate.
- Keep it on a hot plate at 70 Deg c for half an hour.
- Add 10 ml of 10 % barium chloride and heat it for half an hour.
- Filter with Whatman filter paper no.42 and wash the precipitate with hot DM water until the filtrate is chloride free.
- Weigh empty crucible (W1).
- Put the filter paper and residue in the crucible and ignite at 800 deg C in muffle furnace for half an hour.
- Cool it in desiccators and weigh (W2).
Calculation:
Sulphur (ADB) = ((W2-W1) X 13.74))/Weight of coal taken for test.
Sulphur (ARB) = (100-TM) / (100-IM) X Sulphur (ADB).
Note : Above method is too much time taking, it takes 3 days for complete chloride free sulfur. so here we look at instant sulfur by bomb washing method.
Determination of Sulfur in Coal By Bomb Washing Method (Rapid Method)
Procedure
After GCV determination remove the bomb and carefully release the pressure by connecting external PVC tube to beaker containing water (Distilled water) for absorption of SO2. Give complete washing to crucible and bomb.
Add 2-3 drops of methyl orange indicator to confirm proper washing.
Add 5 % sodium carbonate 5 ml to reduce the acidity as well as to suppress the other impurities. Boil the solution and 2-3 drops of 1:1 hydrochloric acid to make solution just acidic.
Filter the solution by Whatman filter paper no 41 and wash the paper with hot distilled water until free from acid.
Now put beaker in hot plate and cover it with watch glass. Add 10 ml of barium chloride 10 % solution and keep it in hot plate just before boiling.
Allow the precipitate settle down and filter it by Whatman no 42.
Wash the residue till it is free from chloride.
Take previously heated silica crucible as W1 and keep it in furnace at 815oC+/-10OC.
After ignition remove the crucible from the furnace and cool it in desiccator & weigh say W2.
Note : above procedure is just takes one and half days for analysis of sulfur.
Expression of results:
(W2-W1) × 0.13738 × 100
Total Sulphur % = ————————————–
W
Where,
W1= Weight of empty Crucible
W2= Weight of empty crucible plus ignited residue.
W=Weight of sample taken