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From collection bin to cullet ready for the furnace – a look at the equipment and steps that turn used glass into a valuable raw material.
Glass is one of the few materials that can be recycled indefinitely without losing quality, but turning a skip full of broken bottles and jars into clean cullet ready for re-melting requires a carefully designed sequence of machines working together.
The term glass recycling machine rarely refers to a single piece of equipment. In practice it describes a line of complementary machines – crushers, screens, magnetic and eddy-current separators, washing units and optical sorters – that together convert mixed, dirty, broken glass into cullet: clean, sorted glass fragments of a consistent size that can be melted down to make new glass products.
These lines are found at materials recovery facilities (MRFs) that process household recycling collections, at dedicated glass recycling plants that receive glass from bottle banks and commercial collections, and increasingly within glass manufacturing sites themselves, where manufacturers process their own production waste and post-consumer glass to feed back into the furnace.
The process typically begins with reception and pre-sorting, where incoming glass is inspected for large contaminants – ceramics, stones, metal lids, plastic caps – that need to be removed before the glass enters the line. Next comes crushing, where the glass is broken down into smaller, more uniform fragments using impact crushers or hammer mills, making it easier to handle and sort.
After crushing, screening separates the material by particle size, removing fine contaminants such as paper labels and dust. Magnetic separation then removes any ferrous metal fragments – bottle caps and lids – while eddy current separators pull out non-ferrous metals such as aluminium closures.
The most critical stage for quality is colour and contaminant sorting, where optical sorting systems use high-speed cameras and sensors to identify glass by colour (clear, green, amber) and to detect ceramic, stone or heat-resistant glass fragments – materials that, even in small amounts, can cause defects in new glass if they end up in the furnace. Finally, washing removes any remaining organic residue, labels or fine debris, leaving clean cullet ready for transport to a glass furnace.
Within a typical line, the main categories of equipment include crushers and breakers for initial size reduction; vibrating screens for size classification; magnetic separators and eddy current separators for metal removal; optical sorting systems, which use near-infrared and visible-light sensors to sort glass by colour and to reject ceramics, stones and porcelain (often referred to as CSP contaminants); and washing and drying units for final cleaning. PICVISA's ECOGLASS optical sorting systems are specifically designed for this colour-sorting and contaminant-removal stage, helping plants produce furnace-ready cullet that meets strict purity requirements.
Investing in a properly designed glass recycling line delivers several benefits: it produces higher-purity cullet, which can be sold at a premium and used in higher proportions in new glass production; it reduces energy consumption at the furnace, since melting cullet requires less energy than melting raw materials from scratch; it diverts large volumes of glass from landfill, where it would otherwise take essentially forever to break down; and it gives recycling operators the flexibility to process glass from multiple sources – municipal collections, commercial waste and manufacturing scrap – through a single, efficient line.
Discover ECOGLASS optical sortingGet in touch with our team to discover how PICVISA's optical sorting and robotics solutions can fit your recycling operation.