Method for calcining clay
(22) 25.11.2022
(43) 29.05.2024
(57) Method for calcining clay comprising the steps of providing a clay raw material with an iron content of at least 2 wt.-%, calculated as Fe203 on a loss on ignition at 950 °C free basis with respect to the total clay raw material, forming lumps from the clay raw material with a surface to volume ratio in the range from 0.05 to 1 mm-1 and a size from 5 to 25 mm in the minimum extension, calcining the lumps at a temperature from 450 to 1100 °C under oxidizing conditions to provide calcined lumps, and cooling and grinding the calcined lumps to provide calcined clay, as well as use of the calcined clay to make composite cement and method for manufacturing composite cement or alkali activated binder or road binder by mixing the calcined clay with a hydraulic cement to make the composite cement or road binder or mixing the calcined clay with an activator to make the alkali activated binder.
(71) Heidelberg Materials AG, 69120 Heidelberg (DE)
