Case study of rising cement mill temperatures - incidence of false set

摘要

An investigation into the incidence of false set in production cement due to rising cement mill temperatures is reported, taking into consideration the generally accepted conversion of gypsum into hemihy-drate as the cause of such phenomena. Laboratory studies included solubility tests, consistency and DTA/TGA studies. With a rise in temperature of up to 200 ℃ and subsequent cooling in air to room temperature, the reconversion of hemihydrate to gypsum was found to be around 30 to 40% for the three types of gypsum, namely marine, mineral and chemical.