Glass-Ceramic Foams from Alkali-Activated Vitrified Bottom Ash and Waste Glasses

Both vitrified bottom ashes (VBAs) and waste glasses are forms of inorganic waste material that are widely landfilled, despite having some economic potential. Building on previous studies, we prepared glass-ceramic foams by the combination of VBA with either soda-lime glass (SLG) or borosilicate glass (BSG). Suspensions of fine powders in weakly alkaline solution underwent gelation, followed by frothing at nearly room temperature. Hardened "green" foams were sintered, with concurrent crystallization, at 850-1000 \ub0C. All foams were highly porous (>70%), with mostly open porosity. The glass addition was fundamental in both gelation (promoting the formation of carbonate and silicate hydrated phases) and firing steps. While SLG addition enhanced the viscousflow sintering, without a significant impact on the crystallization of gehlenite, the main crystalline phase from the devitrification of VBA, BSG addition caused a reactive sintering, with remarkable changes in the phase assemblage. The glass addition generally also allowed lower sintering temperatures and yielded products with excellent crushing strength. However, only specific conditions resulted in the complete immobilization of pollutants (e.g., Cr3+ ions)

Low-alkali borosilicate glass microspheres from waste cullet prepared by flame synthesis

Although glass recycling is considered to be a default method for glass waste management, fine fractions of container soda-lime glass, or cullet of other compositions are still landfilled. This happens despite existing alternatives. Success could lie in advanced upcycled products that bring higher economic motivation for the implementation in industry, but these are often connected to alternative ways of product synthesis. We provide an example of waste glass upcycling by the preparation of glass microspheres (GM) from specialty low-sodium alumino borosilicate-based glasses via flame synthesis (FS). GM and the precursors, either from colorless medical vials or glass fibers, were characterized by scanning electron microscopy (SEM), simultaneous thermal analysis coupled with differential thermal analysis (STA-DTA), and image analysis. A dynamic corrosion test was performed and evaluated via ion-coupled plasma with optical emission spectroscopy (ICP-OES) to observe corrosion kinetics products. FS has proved to be a fast method of waste glass processing into GM. This article, besides the characterization of the starting material and final products, also suggests the possibility of processing for other landfilled waste glasses and also discusses the manufacturing of GM for water filters and fillers for polymers

Characterisation and disposability assessment of multi-waste stream in-container vitrified products for higher activity radioactive waste

Materials from GeoMelt® In-Container Vitrification (ICV)™ of simulant UK nuclear wastes were characterised to understand the partitioning of elements, including inactive surrogates for radionuclide species of interest, within the heterogeneous products. Aqueous durability analysis was performed to assess the potential disposability of the resulting wasteforms. The vitrification trial aimed to immobilise a variety of simulant legacy waste streams representative of decommissioning operations in the UK, including plutonium contaminated material, Magnox sludges and ion-exchange materials, which were vitrified upon the addition of glass forming additives. Two trials with different wastes were characterised, with the resultant vitreous wasteforms comprising olivine and pyroxene crystalline minerals within glassy matrices. Plutonium surrogate elements were immobilised within the glassy fraction rather than partitioning into crystalline phases. All vitrified products exhibited comparable or improved durability to existing UK high level waste vitrified nuclear wasteforms over a 28 day period

INFLUENCE OF FINING AGENTS ON GLASS MELTING: A REVIEW, PART 2

The fining agents are substances with numerous effects on glass melting. The second part of our review summarizes both the benefits and disadvantages of fining agents used in the glass industry for the purpose of degassing glass melts and removing bubbles from molten glasses. Particular attention is paid to the usage of sodium sulphate and also to the chemical and physical factors connected with such phenomena as bubble nucleation and the foaming of glass melts

Porous Glass Microspheres from Alkali-Activated Fiber Glass Waste

Fiber glass waste (FGW) was subjected to alkali activation in an aqueous solution with different concentrations of sodium/potassium hydroxide. The activated materials were fed into a methane–oxygen flame with a temperature of around 1600 °C. X-ray diffraction analysis confirmed the formation of several hydrated compounds, which decomposed upon flame synthesis, leading to porous glass microspheres (PGMs). Pore formation was favored by using highly concentrated activating alkali solutions. The highest homogeneity and yield of PGMs corresponded to the activation with 9 M KOH aqueous solution

Efekt litia na skelně přechodové chování bioskla 45S5

Differential scanning calorimetry, thermomechanical analysis and Raman spectroscopy were used to study the role of the Li2O and P2O5 oxides on the structural relaxation phenomena in the Li-doped 45S5 Bioglass. The glass transition behavior was found to be similar for the enthalpy and volume manifestations of the relaxation motions. The Tool-Narayanaswamy-Moynihan (TNM) model was applied. An improved simulation-comparative methodology was used to determine the model relaxation parameters. The TNM model parameters and the selected glass transition characteristics (the glass transition temperature and the coefficients of thermal expansion) showed no statistically significant correlation with the particular elements present in the synthesized glasses. Hence, the information about the glasses composition was used to calculate the theoretical amounts of the Q(Si)(n) species in the Li-doped 45S5 glasses. It was found that practically all explored physico-chemical quantities related to the glass transition kinetics show a correlation with the content of Q(Si)(2) species that are responsible for the formation of the chain-like structures in the present glasses.Metody DSC, TMA a Ramanovy spektroskopie byly použity pro studium efektů Li2O a P2O5 na strukturní relaxaci Li-dopovaného bioskla 45S5. TNM model byl použit k popisu strukturní relaxace v oblasti skelného přechodu. TNM paramtery, teplota skelného přechodu a koefficient teplotní expanze nevykázaly žádnou významnou korelaci se složením syntetizovaných skel