Biological Process And Processing: The Process Of Acid Leaching

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Acid leaching is the process of reacting unwanted minerals on the coal with the aqueous acid solution in order to create removable salts in an aqueous setting. This leaching, with certain Acids, is unable and can rarely remove the organic sulfur. For example, a solution of 15% Hydrogen peroxide alone was able to remove 70% sulfur sulfate, 76% pyritic sulfur, 5% organic sulfur and 14% ash at 25˚C (Meshram, Purohit, 2015). However, by adding 0.1 mol/L Sulfuric Acid to act as a catalyst, almost all of the sulfur sulfate and pyritic sulfur, 43% of the ash, and over 26% of the organic sulfur were removed (Meshram, Purohit, 2015). The catalyst improves the reaction by moving the oxygen and pyrite molecules together so that they may react easier. The Acid leaching process often involves two …show more content…

Coal is decayed plant or animal matter that has been altered by some biological process and a geological process over a large time frame. Biological processes have the ability to remove organic sulfur but have not been employed commercially (Ohtsuka, 2000). An advantage that the biological processes retain over the other methods is the temperature and pressure needed are able to be very low, reducing energy, whereas other process can have a temperature up to 1350˚C and a pressure of 140 atm (Faison, 1991). The biological process of removing pyritic sulfur is generally believed to have two methods: the indirect and direct methods. The indirect method removes the pyritic sulfur through the oxidation of the pyritic sulfur through the use of ferric ions. This route is 106 times slower than the direct route (Groppo, Parekh, 1993). The direct method is defined as a process where microorganisms are attached to the surface of the pyrite and enzymatically oxidize the sulfur, proving to be much more efficient with

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