No abstract

No abstract

The effect of a set of external factors on the redox equilibrium of iron and sulfur, changes in melt properties, and light transmission of clear sheet glass is investigated for continuous production of glass. A quantitative estimate of trends in the variations of the redox potential of glass melt is proposed. Practical measures improving the efficiency of a tank furnace by correcting the oxidation state of the melt are considered.A prompt response to problems of stabilizing the glassmelting process in continuous production is an essential factor in producing high-quality products. This is especially important in the case of significant changes occurring in the process, such as a modification of the batch : cullet ratio or the glass compositions, using different grades of materials, etc. These modifications result in the process parameters going beyond the technological standards. As a consequence, glass quality is often impaired and the production volume decreases.The experience shows that in carrying out the above specified works it is important to adequately estimate the current situation and to use various techniques to stabilize the prescribed redox potential (ROP) of the glass melt. Note that such technological situations cannot be to a full extent simulated in the laboratory conditions in view of their complexity; therefore, laboratory results, as a rule, differ perceptibly from data obtained in continuous industrial furnaces. Therefore, it is necessary to study in detail the regularities of the variations of the redox state and technological properties of glass melt in continuous production.The factors influencing the glass melt in continuous production can be arbitrarily divided into two groups:-staff-controlled systems (hereafter "controlled" systems); they include the batch ROP, the chemical composition (basicity) of the glass, the furnace temperature conditions, and the gas : air ratio;-uncontrollable factors, such as variations in the granulometric composition of materials, fluctuations in composition of gas-air mixtures fed to the furnace for combustion, and uncontrolled impurities brought by materials, i.e., iron from refractories and sulfurous compounds from the fuel.As a rule, uncontrolled factors in practical glass melting are neglected due to their diversity and narrow variation limits; the lack of statistical data due to irregular or lacking monitoring of these factors aggravates the problem. We should especially stress the impurities of the variable-valence elements (VVE), namely iron (d element) and sulfur ( p element) coexisting in the melt in the state of the redox equilibrium [1]:Laboratory studies of silicate glasses of a simple composition have demonstrated that the ratio between the oxidized and the reduced forms of these variable-valence elements may vary within wide limits and is closely related to the controlled factors of the first group. A decrease in the batch ROP, and increase in melting temperature, a decrease in glass basicity, or transition from the oxidizing atmosphere to the...

No abstract

No abstract