ANALYSIS OF GLASS DEFECTS CAUSED BY THE MELTING OF BATCH WITH A HIGH CONTENT OF GLASS CULLET

Abstract

The utilization of recycled cullet reduces significantly glass production costs. Every 10 percentage points of recycled glass used in the manufacture of container glass saves about 3.5% of energy and 11% of raw materials. To use cullet in high quantities (more than 70% for container glass), the cullet has to meet some demands, and only some ppm of metals, ceramics, porcelain and pyro-ceramics are permitted. A source of metallic inclusions may be the fine-grade fraction of the cullet with the particle diameter less than 5 mm, which cannot be easily separated from glass waste. Upon increasing the recycled cullet quantity from 20% to 80%, in the glass manufacture stock company “Kauno stiklas” a new type of non-dissoluble glass defects has been detected. It was determined that spherical inclusions are mainly due to elementary silicon and a small quantity of iron silicide. Another biggest and cylindrical solid inclusion is composed by aluminum silicate mullite.
The main methods of separating metallic and mineral inclusions from glass cullet have been examined.

DOI: http://dx.doi.org/10.5755/j01.ct.59.1.1526