Desulfurization of Mae Moh Coal from Thailand by Leaching with Sodium Hydroxide and Potassium Hydroxide

Bantita Terakulsatit

Abstract


Low rank coal of Mae Moh coal field in Thailand is suitable only for feeding coal fired power plants due to a high ash and sulfur contents, and low heating value. Reduction of sulfur and heavy metal elements are also in use physical, chemical and biological methods. Many chemicals such as HF, HNO3, HCl, NaOH, KOH and others are used to reduce sulfur and ash for upgrading coal. The objective of this investigating to determine the effects of KOH and NaOH solutions on the desulfurization from K and Q coal seams in the high sulfur of Mae Moh coal. The analysis result of the K coal seam, the sulfur content is mainly reduced about 6.8% by KOH and 3.6% by NaOH. Pyrite content has reduced about 67% by either of KOH and NaOH. Gypsum content has decreased 86.9% by KOH, 73.5% by NaOH. Moisture content reduced about 36.6% by KOH and 41.1% NaOH, and the hydrogen content also decreased 69.6% by NaOH and increase 56% by KOH. The carbon content has increased about 3.7% by NaOH, but decrease 7.2% by KOH. The volatile mater and fixed carbon contents have reduced by both of base solutions.  The increasing of calorific value is 45.2 MJ/kg by KOH. The result of the Q coal seam, the sulfur content is mainly reduced about 20% by KOH and 4.1% by NaOH. The pyrite content can be approximately reduced 60.5% by NaOH and 48.2% by KOH. The gypsum content is reduced 91.7% by KOH and 90.1% NaOH. The moisture content can be reduced 41.1% in NaOH and 31.1% by KOH. The volatile content increases 5.8% by KOH and 7%. The sodium hydroxide solution is also increased 0.4% of the fixed carbon and 7.5% carbon contents. The potassium hydroxide decreases 0.3% and 23.4%, 0.4% and 7.5% of the fixed carbon and carbon contents, respectively. The calorific value has only increased by KOH about 14.64 MJ/kg. Both of base solutions have increased the ash content. In conclusion of this investigation, the potassium hydroxide is higher efficiency than the sodium hydroxide solutions, due to its potential to the optimum sulfur, pyrite and gypsum reductions and also increases the carbon, fixed carbon and calorific value contents.


Keywords


desulfurization, sulfur, Mae Moh coal, sodium hydroxide, potassium hydroxide

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References


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