Design of Self-Flow Chemically-Bonded Castables
Considering the fast reaction rate of acid-base transformations, their exothermic feature and difficulties to optimise particle dispersion in acid medium, phosphate-bonded products are usually placed via gunning, hand packing or vibration. This work focused on developing high-alumina self-flow chemically-bonded castables for petrochemical/aluminium industries, based on adding sodium polyphosphates and phosphoric acid and monoaluminium phosphate solutions. Flowability, working and setting time, cold and hot mechanical strength, porosity and thermal shock measurements were carried out in order to evaluate the performance of the designed refractories. According to the results, the presence of sodium polyphosphates improved the castables’ flowability, resulting in maximum free-flow of 120–160 %. When compared to a vibratable phosphatebonded commercial product, the developed castables containing H3PO4 and MAP solutions presented higher mechanical strength and thermal shock resistance, in addition to their self-flow behaviour.