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Calcium Looping Spent Sorbent as a Limestone Replacement in the Manufacture of Portland and Calcium Sulfoaluminate Cements
- Telesca, Antonio, Marroccoli, Milena, Tomasulo, Michele, Valenti, Gian Lorenzo, Dieter, Heiko, Montagnaro, Fabio
- Environmental Science & Technology 2015 v.49 no.11 pp. 6865-6871
- bauxite, calcium, carbon dioxide, cement, combustion, ecosystem services, energy conservation, fluidized beds, greenhouse gas emissions, gypsum, industrial byproducts, limestone, raw materials, sorbents
- The calcium looping (CaL) spent sorbent (i) can be a suitable limestone replacement in the production of both ordinary Portland cement (OPC) and calcium sulfoaluminate (CSA) cement, and (ii) promotes environmental benefits in terms of reduced CO₂ emission, increased energy saving and larger utilization of industrial byproducts. A sample of CaL spent sorbent, purged from a 200 kWth pilot facility, was tested as a raw material for the synthesis of two series of OPC and CSA clinkers, obtained from mixes heated in a laboratory electric oven within temperature ranges 1350°–1500 °C and 1200°–1350 °C, respectively. As OPC clinker-generating mixtures, six clay-containing binary blends were investigated, three with limestone (reference mixes) and three with the CaL spent sorbent. All of them showed similar burnability indexes. Moreover, three CSA clinker-generating blends (termed RM, MA and MB) were explored. They included, in the order: (I) limestone, bauxite and gypsum (reference mix); (II) CaL spent sorbent, bauxite and gypsum; (III) CaL spent sorbent plus anodization mud and a mixture of fluidized bed combustion (FBC) fly and bottom ashes. The maximum conversion toward 4CaO·3Al₂O₃·SO₃, the chief CSA clinker component, was the largest for MB and almost the same for RM and MA.