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

Abstract

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.