Effects of particle size and briquetting of soda‐lime‐silicate glass batch on viscosity during batch‐to‐melt conversion

Abstract

To assess the effects of grain size and briquetting on glass‐batch melting, we measured the viscosity (ηb) of an industrial glass batch during its conversion to molten simulated architectural glass within the temperature interval of 1050‐1300°C and at a shear rate of 0.02 s−1. On the basis of the mass fraction of undissolved sand (xs), which was determined using X‐ray diffraction analysis on quenched batch samples, and the gas‐phase fraction (ϕp), which was obtained from volumetric measurements, we established the relationship ln(ηb/ηm) = a0 + bsxs + apϕp, where ηm is the transition melt viscosity, a0 is the melt homogeneity coefficient, bs is the coefficient for undissolved sand, and ap is the coefficient for bubbles. The obtained values, bs = 8.756 and ap = 0.658, indicate that undissolved silica sand strongly influences batch viscosity. Consequently, compared with coarse‐grained batches, fine raw materials and briquetting resulted in lower batch viscosity during conversion. Owing to their lower viscosities and higher heat conductivities, batches from finer raw materials or batches shaped into briquettes are expected to enhance the melting rate of batch blankets in industrial glass‐melting furnaces.

Transient melt formation and its effect on conversion phenomena during nuclear waste vitrification – HT‐ESEM analysis

“…59 These techniques allow us to observe and investigate the primary foam behavior in a broad range of commercial and waste glass batches, have been used to develop kinetic models for their conversion, 27 and were implemented in the computational dynamics model of glass melters. 8,60 Although the effects of batch formulation and pre-treatment on the extent of primary foaming were analyzed in the past, [61][62][63] their fundamental understanding is still lacking. The three main questions are: How do the properties of the transient glass-forming melt, such as viscosity, surface tension, or density, change during the conversion process?…”

Modeling batch melting: Roles of heat transfer and reaction kinetics

“…Alternatively, the batch:melt interface can be visually observed in a transparent (quartz glass) laboratory‐scale melter vessel. While in situ laboratory observation of the batch‐to‐glass conversion in a test tube containing the batch is common, to the best of our knowledge, observing foam during a steady‐state melting process has not yet been attempted. This can be achieved by melting the batch on the top of the glass melt while leaving a portion of the melt surface free of the batch for the gas bubbles to escape from below the batch.…”

Enhanced Reactivity and Primary Liquid-Phase Forming in Mechanochemically Activated Soda–Lime–Silica Glass Batches

“…Often oversimplified as a simple melting and cooling process, the thermally induced chemistry of a glass-making batch is very complex and includes several consecutive or concurrent reaction steps, such as dehydration reactions, polymorphic transformations, decomposition and solid-state reactions, and melting and dissolution processes . Moreover, the temperature, the kinetics, and even the nature of some of these processes are significantly affected by changes in process variables, such as chemical composition and particle size and heating rate, or by the presence of additives, to mention a few. − Milling has been traditionally used in industry for mixing reactants and reducing their particle size; however, the recent availability of high load and more powerful milling devices and appropriate milling tools, as well as the advances gained in understanding the fundamentals of mechanochemical reactions, have opened a whole new world of possibilities, and triggered renewed interest in the subject. Therefore, milling has become a very important venue of research for the large-scale and “green” production of almost any type of substance, including inorganic, organic, and organometallic compounds and composites. − Furthermore, grinding mixtures of raw materials in high-energy mills stimulates physical and chemical changes and increases chemical reactivity during additional processing. − Since much of the energy required in the production of glass is consumed in decomposing the carbonated raw materials (i.e., soda ash, calcite, and dolomite) and forming the first liquid phases, this contribution focuses on the effect of high-energy milling in both steps of glass manufacturing; special emphasis is placed on analyzing the evolution of the coordination environment of Si atoms, with milling time and temperature.…”