Glass manufacturing is a high-temperature, energyintensive, and highly inefficient process, with a significant global environmental impact. Therefore, given the high-scaled nature of the glass-making sector, the design of more energy-efficient manufacturing protocols is an economic and environmental imperative. In this context, this work presents a comprehensive study about the milling effect in the heat-driven chemistry and phase evolution, of a typical soda−lime−silica (Na 2 O:CaO:SiO 2 ) flat glass batch. Our findings show that, with the experimental settings imposed in this work, mechanochemical reactions leading to in situ formation of alkali/alkaline-earth silicate compounds in the vial, are most likely absent. However, all carbonated raw materials of the formula (soda ash, calcite, and dolomite), undergo severe structural damage during milling and even become amorphous to XRD after milling for 360 min, with their decomposition reactions shifting markedly toward lower temperatures as the milling time increases (e.g., the volatile fraction of the formula activated for 360 min, is completely removed almost 200 °C below than of a nonactivated reference sample). Furthermore, milling has also a profound effect in the evolution of the silicon local coordination environment, with temperature, and in the formation temperature and stoichiometry of silicate species observed on heating. Moreover, events related to the depolymerization of the fully linked Q 4 units characteristic of crystalline SiO 2 (i.e., formation of metal silicates), are observed in activated batches at temperatures well below those of the reference sample (e.g., 600 °C when activated for 360 min vs 900 °C of a nonactivated sample). These changes are not only a consequence of particle size reduction, because the particle size distribution of the batch does not change much after 30 min; milling-induced amorphization of the carbonated fraction of the formula and the corresponding reduced activation energy for their decomposition reactions and improved reactivity toward SiO 2 are the driving forces behind the significant reduction in the formation temperature of the first liquid phases with increasing milling time.
An initial mixture of raw materials (batch) typically used for the manufacture of conventional soda-lime float glass was subjected to a mechanical activation process for 30 or 60 minutes in a planetary ball mill. An intensification of the chemical reactivity of the batch, which was directly related with the increase in the milling time, was observed. This accelerated the chemical reactions that took place during the batch melting process between sodium, calcium and magnesium carbonates and other components of the mixture, which happened at significantly lower temperatures with respect to the batch without mechanical activation. The heat of fusion of the batch, estimated using a methodology previously reported in the literature, indicated that the mechanical activation given to the initial mixture of raw materials decreased the energy consumed during the batch melting. This was also evidenced by a decrease in the temperature at which the release of CO2 ended, which was considerably larger than that previously reported in the literature based solely on the decrease in the particle size of a batch of similar composition achieved by dry sieving.
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