title: Leaching of valuable elements from thermal power plant bottom ash using a thermo-hydrometallurgical process.
abstract: The solid industrial wastes generated from thermal power plants (TPPs) can be considered as renewable secondary sources for recovery of valuable metals. This study presents the results from investigations that integrated a thermo-hydro-metallurgical method for treatment of bottom ash obtained from the Enel Maritsa East 3 TPP in Bulgaria. Leaching was performed with 20, 30 and 40 wt% sulphuric acid, respectively, in an autoclave at 100(o)C, 120(o)C and 140(o)C for 120, 240, 360 and 480 min, at a constant value of the liquid/solid ratio. After autoclaving, the samples (suspensions) were diluted with a constant value of water and stirring at 50(o)C for 60 min. On the basis of the experimental data the leaching efficiency (α) of the elements in the liquid phase after filtration was estimated. The leaching of aluminium increases significantly with increasing of the temperature, reaching the maximum value of 70 wt%. The highest leaching efficiency values for the other elements are as follows: Fe (86.4%), Ca (86.6%), Na (86.6%), Ni (83.3%) and Zn (83.3%). The maximum value of leaching for Mg, K, Mn, Cu and Cr is in the interval of 46-70%.
authors.affiliation: University of Chemical Technology and Metallurgy, Bulgaria.
authors.forename: Darinka
authors.initials: D
authors.lastname: Bojinova
authors.affiliation: University of Chemical Technology and Metallurgy, Bulgaria rteodosieva@abv.bg.
authors.forename: Ralitsa
authors.initials: R
authors.lastname: Teodosieva
mesh_terms: D002031:Bulgaria; D060729:Coal Ash / Q000737:chemistry*; D007220:Industrial Waste; D008669:Metallurgy / Q000379:methods*; D008670:Metals / Q000302:isolation & purification*; D012037:Refuse Disposal / Q000379:methods; D013464:Sulfuric Acids / Q000737:chemistry; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D060729:Coal Ash; D007220:Industrial Waste; D008670:Metals; D013464:Sulfuric Acids; C033158:sulfuric acid
keywords: Bottom ash; leaching efficiency; sulphuric acid dissolution; thermal power plant; waste processing