Influence of granulated milled slag glass additive on hemihydrate phosphogypsum hardening

A mechanical activation method for saving the accumulated waste energy (about 160 kWh/t) found in phosphogypsum was investigated and developed. The state of phosphogypsum in which it is disposed to stackpiles can not be used for production of construction materials due to the acidic admixtures present in it, which block its hydration and hardening processes, so new methods for neutralizing this negative effect were investigated. In earlier investigation, various energy consuming additives like Portland cement and lime were used, so the construction material products integral energy expenditures were high. Slag glass could be used for neutralization, hydration and hardening kinetic regulation of phosphogypsum acidic admixtures. The aim of this investigation was to determine the interaction of slag glass with the acidic admixtures present in phosphogypsum. It was found, that slag glass is an effective neutralizing additive for acidic admixtures present in phosphogypsum, which allows to regulate the phosphogypsum hydration and hardening duration and also to replace the energy consuming additives like Portland cement and lime proposed earlier.