Main drivers for integrating zinc recovery from fly ashes into the Viennese waste incineration cluster

Abstract

In Vienna approximately 1milliontons of waste is incinerated annually. Therefore 13 lines of waste incineration, including fluidized bed incinerators, rotary kilns and grate furnaces, are in operation. Beside municipal solid waste, hazardous waste as well as communal sewage sludge are utilized. All incinerator lines use a wet flue gas cleaning system. Based on the zinc, lead and copper concentrations in its solid residues and knowledge on the mass flow of the residues, a detailed material flow analysis is carried out, that determines the total throughput of these metals. It turns out that 800t of zinc, 300t of lead and 550t of copper pass through Vienna's waste incineration cluster annually. Approximately half of the zinc can be found in the fly ashes of the waste incinerators investigated. In Switzerland a process that recovers pure zinc (>99.99%) as well as a mixed fraction of lead, copper, zinc and cadmium out of waste incineration fly ash, has been realized at full scale. A comparison between the expected operational costs, on the one hand, and the anticipated revenues from recovered metals and reduced disposal costs resulting from the application of this technology to the investigated waste incinerators, on the other, is discussed within this work. Main drivers responsible for the economical non-applicability to Vienna, are examined.