Production of low-CO2 calcium sulfo-aluminate ferrite clinker from bauxite residue

Bauxite residue (BR) is the main waste of the alumina sector produced at rates of 7 million tons per year in the EU. The recycling rates are less than 100 thousand tons per year, however in the EU-funded Horizon 2020 project ‘Industrial Residue Activation for sustainable cement production - ReActiv’ modification will be made to both the alumina production and the cement production side of the chain, in order to link them through the new ReActiv technologies. The properties of the BR will be modified, transforming into an active material ( with pozzolanic or hydraulic activity) suitable for new, low CO2 footprint, cement products. The BR will be incorporated with limestone , gypsum and other alkali-silicate materials (if necessary) to produced the modified CSA clinker. The mix composition will be based on the thermodynamic modelling and the use of modified Bogues equations. A suitable mix composition will be adopted for clinker production based on the aimed target phases of the clinker. The obtained phase assemblages will be further confirmed by QXRD, TGA-DSC and EMPA-WDX. Furthermore, hydration studies of the cement pastes will be investigated followed by the evaluation of the mortar properties. The optimum clinker recipe will be used to produce large scale clinkers for evaluation and testing at the pilot plant of Lafarge Holcim