Process for preparing reactive calcium-aluminate materials of ammonia alum

摘要

The invented process for preparing reactive calcium-aluminate materials is characterized by employing ammonia alum as argillaceous raw material. The ammonia alum being either directly or after conversion by ammonia to oxohydroxide and/or aluminium hydroxide is mixed with calcium carbonate or oxide and optionally with a recycling fraction of a resulting calcium-aluminate product in such a manner as to assure in the obtained raw mixture a molar ratio CaO : Ali2Oi3 equal to or greater than 1. So prepared reaction mixture is then ground, homogenized, optionally subjected to granulation and subsequently it is heat treated at temperatures higher than 800 degC. The invented reactive calcium-aluminate materials can be employed for reducing content of sulfates in water discharged in a recipient or as special building materials.