Role of magnesium chloride in the performance and phase composition of lead glass sludge foam

•Lead glass sludge (LGS) was prepared with no foaming agent addition.•Adding MgCl2 caused a notable retardation in foaming process at all temperatures.•MgCl2 enhanced LGS crystallization by the formation of diopside and cristobalite.•A significant decrease in Pb-leaching rate was achieved by adding MgCl2. In the present work, different MgCl2 dosages were admixed with lead glass sludge (LGS) to evaluate their effects on the performance of the produced LGS-foam at different elevated temperatures. The results revealed that adding MgCl2 caused a negative impact on the bloating process, including porosity and volume expansion reduction, as well as bulk density and thermal conductivity increment. This was associated with the high affinity of magnesium for enhancing the crystallization of LGS through the formation of diopside and cristobalite minerals. Moreover, the speed up of softening temperature of LGS using MgCl2 makes LGS completely softened before full dissociation of CaCO3, decreasing gas entrapping inside the softened LGS. Nevertheless, the use of MgCl2 decreased the free Pb inside LGS through thermal/chlorination process.