Special Issue 1, December 2009
Article Number: 06
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Optimization of leaching metals with sulfuric acid from TPS bottom ash

A.S. Meawad, D.Y. Bojinova, Y.G. Pelovski, and D.L. Damgaliev
Pages 27-31

Abstract—Lignite coal burned in Maritsa East thermal power station (TPS) in Bulgaria generates bottom ash used as a secondary raw material for extraction of different elements. This paper presents the results of leaching different metals such as Al, K, Na, Ca, Mg, Fe, Cu, Zn, Ti, As, Mo, Cr, Ni and Ba from bottom ash. Leaching rate determining factors are concentration of sulfuric acid (X1), temperature (X2), the non-stoichiometric norm (X3) and time of leaching (X4). D-optimal plan for second order model was applied. On the basis of the experimental data that has been obtained adequate regression equations are derived. It was found that at temperature 80C with 45% wt sulfuric acid and non-stoichiometric norm = 600 for 90 minutes, 49.32%, 38.5%, 32.7%, 29% and 26.38% of Zn, Mn, Na, Mg and Fe, respectively, are transferred into the liquid phase, when some other elements like Ca, K, Al, Ti, and As the efficiency much less (ranged from 11 to 16%). Higher extraction efficiency of metals is obtained by extending the range of sulfuric acid concentration and non-stoichiometric norm.

Keywords—bottom ash, leaching, optimization, Thermal power station.