Potential of Waste Shells as a Source of Calcium for Soda-lime-silicate Glass

To achieve carbon neutrality and establish a circular economy, glass manufacturers must significantly reduce CO2 emissions and waste. This includes addressing CO2 emissions that do not originate from energy production, such as those from carbonates like CaCO3 and Na2CO3. CaCO3, commonly used in industrial processes, is also a major component of shells and eggshells. These waste shells represent an underutilized resource that can contribute to carbon neutrality by reducing CO2 emissions. In this study, soda-lime-silicate glass was manufactured by substituting waste shells for limestone, a traditional raw material in glass production. The findings confirmed that pearl shells, black pearl shells, white pearl shells, scallops, and oysters could effectively replace limestone in soda-lime-silicate glass manufacturing. This suggests that incorporating discarded shells as raw materials in glass production has the potential to reduce waste and lower CO2 emissions. Additionally, it was observed that the type of waste shell and applied heat treatment influenced the color, homogeneity, and foaming properties of the resulting glass.