title: Evaluation of a lime-mediated sewage sludge stabilisation process. Product characterisation and technological validation for its use in the cement industry.
abstract: This paper describes an industrial process for stabilising sewage sludge (SS) with lime and evaluates the viability of the stabilised product, denominated Neutral, as a raw material for the cement industry. Lime not only stabilised the sludge, raised the temperature of the mix to 80-100°C, furthering water evaporation, portlandite formation and the partial oxidation of the organic matter present in the sludge. Process mass and energy balances were determined. Neutral, a white powder consisting of portlandite (49.8%), calcite (16.6%), inorganic oxides (13.4%) and organic matter and moisture (20.2%), proved to be technologically apt for inclusion as a component in cement raw mixes. In this study, it was used instead of limestone in raw mixes clinkerised at 1400, 1450 and 1500°C. These raw meals exhibited greater reactivity at high temperatures than the limestone product and their calcination at 1500°C yielded clinker containing over 75% calcium silicates, the key phases in Portland clinker. Finally, the two types of raw meal (Neutral and limestone) were observed to exhibit similar mineralogy and crystal size and distribution.
authors: Eduardo Torroja Institute for Construction Science (CSIC), Serrano Galvache 4, 28033 Madrid, Spain. nuriah@ietcc.csic.es
authors: N Husillos
authors: NH
authors: Rodríguez
authors: R J
authors: RJ
authors: Granados
authors: M T
authors: MT
authors: Blanco-Varela
authors: J L
authors: JL
authors: Cortina
authors: S
authors: S
authors: Martínez-Ramírez
authors: M
authors: M
authors: Marsal
authors: M
authors: M
authors: Guillem
authors: J
authors: J
authors: Puig
authors: C
authors: C
authors: Fos
authors: E
authors: E
authors: Larrotcha
authors: J
authors: J
authors: Flores
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D002126:Calcium Hydroxide / Q000737:chemistry; D003252:Construction Materials; D010087:Oxides / Q000737:chemistry*; D010865:Pilot Projects; D059027:Recycling; D012722:Sewage
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D012722:Sewage; C016538:lime; D002126:Calcium Hydroxide