A way forward for glass recycling

[Correction: Contrary to the assertion in this article A way forward for glass recycling which appeared in Waste Management World January-February 2009 (Volume 10, Issue 1), LCL Inc has informed us through its lawyers that in fact its MRF purification plant had not been had not been commissioned by Krysteline by January 2009. LCL is presently taking steps to ensure that LCL can commission its plant just as soon as possible so that it can produce crushed glass.] The economic and legislative need to recycle ever more materials from the waste stream is the reason for the modern materials recycling facility, but to date they have struggled to recover high quality glass. A technique designed by UK company Krysteline provides a solution to this situation and could pave the way for new types of glass recycling equipment by Stephan Michal The legislative pressure on municipal authorities means they are striving to meet ever higher recycling targets whilst reducing costs, and this has helped drive the general trend away from segregation, towards the co-mingling of recycling waste collections. Impetus is also added by the need to optimize kerbside collections, reduce costly waste truck crews and journeys – which contribute to the authorities’ carbon footprint and overall operating costs. The refined imploded glass product is safe to handle Click here to enlarge image Typically, the municipal authority contracts a specialist waste management company with a proven track record, to build, manage, and operate material recovery facilities (or MRFs), which utilize the latest specialist separation technologies on approved sites within the authority. These are long-term relationships, and, not only are recovery targets shared, but the financial viability of the facility itself is founded upon its ability to separate and recover materials that will attract the maximum positive value. Traditionally, paper, aluminium, plastic and steel have been the main targets of MRF operators – due to availability of modern and reliable of extraction technology and the gate value these products attract when recycled. Why take glass to a MRF? Recycling targets are typically tonnage-based, and the weight of glass makes it an attractive product to recover, so authority recycling officers are driving their waste management partners to take glass as part of the co-mingled waste stream. Furthermore, as new MRF facilities are being planned, the ability to separate and recover a co-mingled glass feedstock is being ‘designed in’ to new tenders as a prerequisite. Until recently however, MRF operators have struggled with glass separation because the only method of processing a glass-inclusive waste stream was by means of the traditional crusher-type technology, and many early MRF installations were set up in such a way that they excluded glass completely from their contracted input feedstock. typical pre-processing waste feedstock from which glass is extracted Click here to enlarge image This old crushing technology was originally invented for the mining industry in the 1960s for crushing rocks, and when adapted to crush glass it encounters a number of operational problems. The crusher is essentially a blunt instrument, beating the glass into submission and treating all other products that pass through it in the same way. This causes glass particles to be impregnated into the high value products such as paper and plastics, and thus lowering their recycled value. Glass is also very hard and abrasive, and the slow-speed crusher, which has a high power consumption, suffers from constant wear problems. The sharp crushed glass also abrades the MRF processing equipment it comes into to contact with, typically increasing wear rates by over 100% compared with other waste streams. After all separation techniques have been applied a residual glassy mixture of plastic, paper and metals remains – until now it has not been possible to effectively screen and recover any value from this. the LCL computer-controlled processing plant drier Click here to enlarge image Residual is the curse of the recycler – although it often has a high glass content, the quality of it is too low for re-melt or even aggregate use. It counts against overall purification targets, and sits firmly on the loss side of the recycler’s balance sheet. Residual ultimately ends up in landfill. The UK’s agency DEFRA revealed recently that 9% of all waste delivered to MRFs in the UK was rejected due to glass contamination, and according to Joan Ruddock, Minister for Waste and Climate Change, sorting capability was ‘variable’. Rejected waste collections end up in landfill, and this problem has been mirrored worldwide. What is glass implosion? Krysteline, a UK-based company, offers a new solution called ‘implosion’ which is capable of offering the best of both worlds – separating and extracting re-melt quality glass from a MRF – without degrading the other high value materials. This technology works by reducing the glass size using frequency – similar to an opera singer hitting a high note that shatters a wine glass, or a very powerful tuning fork. Simplistically, this means glass can be liberated from difficult mixed waste without affecting the collateral materials. the refined glass product leaving the plant Click here to enlarge image Implosion does not grind, mill, hammer or flail the glass, therefore the high wear associated with traditional glass processors is vastly reduced. The technique produces a range of fraction sizes, from approximately 0.2mm up to 30mm and the resulting glass is sharp-free and safe to handle. Container, flat, toughened, heat-treated and CRT glass can all be imploded – even full sealed bottles, thus saving disposal time with faulty or out of date stock. Implosion technology is ‘tuned’ to process just the glass within the co-mingled waste stream, leaving valued products such as paper, plastic and beverage cans undamaged. glass particle sizes can be changed according to end-product requirements Click here to enlarge image The process operates at high speed but uses low torque, and therefore typically consumes a quarter of the power of an equivalent glass crusher. The product can be reduced to any required size, from large particles suitable for colour sorting and re-melt, to a fine sand-like product suitable for use in high value industrial applications. The discovery of implosion Implosion was invented by Krysteline as a solution to satisfy tough new environmental legislation introduced in the early 1990s that prohibited the dumping of waste at sea by the world’s marine industry. The major cruise lines were required to store their waste rather than disposing of it overboard, and this demanded a new approach to the handling of all waste streams. It ultimately resulted in the introduction of today’s ‘clean ship technology’, which utilizes the latest systems combined with state-of-the-art incineration to handle all waste compliantly. However, due to the volume of beverages consumed (an average of 2.2 kilograms per person per day) and the fact that it is not possible to burn glass, waste bottles remained a massive problem – a new type of glass processor was required that would condense glass to reduce valuable storage space and make it safer for handling. The processor also needed to be rugged enough to withstand the tough marine environment, in addition to being reliable, easy to maintain and hard-wearing. The first compact four-tonne-per-hour processor was developed in 1994 to fit the requirement. Due to their reliability, low power consumption and ease of maintenance, imploders quickly became the standard for the major cruise lines, and marine processors now account for more than fifty of the company’s installations worldwide – with P&O recently installing the latest system on one of their ships. Imploders have also been adopted by NATO for use in British Royal Navy warships. Due to environmental and legislative demands, Krysteline decided to further develop and upscale the imploder to deliver higher performance land-based solutions capable of processing mixed glass and other waste streams. This has resulted in the installation of implosion systems across the world, including the Falkland Islands where all the glass is processed through imploders and transformed into aggregate for island development, thus eliminating all waste glass costs. Developing implosion for MRF integration Following increasing success with difficult glass waste streams, in 2006 Krysteline was approached by a major glass processor in Asia to help solve a specific problem with their glass recycling facility. The goal was to remove the valuable plastic tops and security rings from residual bottle necks, and thus free the glass up for use in re-melt. Following trials, the imploder was made capable of removing the plastic (whole and undamaged) from the glass, resulting in the installation of the system in two more MRF plants. Independent evaluation The implosion process was the subject of a recent study by the UK government’s recycling group WRAP (www.wrap.uk.org) and the results are published in its report, Glass From MRF’s: Can It Be Improved? The trial set out to discover whether it was possible to recover higher value re-melt glass from the MRF residual waste due for landfill. WRAP found that glass can be imploded and extracted from residual waste, which was not previously possible, and a range of products produced, roughly half of which were big enough to go back into re-melt after they had been colour sorted. Latest developments The recent introduction of Autoclave, and similar steam and heat treatment technology, capable of processing MSW or black-bag waste to a virtually sterile fibrous product, has now presented a new market sector for the imploder. With 5%–7% of glass present in the Autoclave waste stream, the imploder has been effective at targeting and reducing the glass, enabling its extraction and reuse, and thus increasing the value of the compost of fibre fuel products. Furthermore, a variety of exciting and diverse new areas for waste processing development have now emerged for the imploder, namely with high volume products that previously have proved to be un-recyclable. These include glass in compost, seashells, auto ceramic catalytic converters, and trainer shoes. Despite the current downtown in most recycled product prices, the cost of landfill will not be going down – which emphasizes the need to extract quality material from the waste stream. Krysteline implosion technology enables the extraction of clean glass from the most difficult of waste streams. The glass is suitable for use in a variety of end markets, and can often be reused domestically to satisfy local product consumption, rather than being dependent on more volatile foreign recycling markets. In the future, implosion may also prove to be the technology that unlocks the secret of recycling many other products and diverting them away from landfill. Stefan Michal is managing director of Krysteline Group Ltd e-mail: stefan.m@krysteline.com Case studies Following installations in the UK and Asia, Krysteline’s latest MRF purification plant has recently been commissioned in Pennsylvania, USA, for LCL Inc. The system will process up to 40,000 tonnes of waste glass per annum, and is designed to take a feedstock which is too contaminated for normal processing and destined for landfill, at a cost of US$100 per tonne. The computer controlled plant uses multiple imploders and a specially developed waterless cleaning system which purifies the recovered glass into high-value glass crystals. These can be sold on as industrial products, such as grit blast or water filtration media. The computer-controlled system uses multiple imploders Click here to enlarge image Approximately 40% of US industry is on the American east coast, and there is a high demand for expendable glass media. LCL is therefore focusing on grit blast, sport turf dressing and water filtration media. Krysteline is currently integrating imploders into a new MRF installation in England, for the waste management company Viridor Waste Management. To convince Viridor of its credentials the imploder had to undergo a series of trials, including the implosion of glass within a mixture of shredded paper, plastic, metals and other difficult-to-separate materials. The positive results ensured that the recovered glass could be used for local engineering projects or within the re-melt industry. This project is one of the new generation MRFs with glass input designed from the outset, rather than being added on as an afterthought. Viridor’s aim is to recover high percentages of quality material. A MRF can typically purify up to 85% of its feedstock, but with the introduction of implosion this could now be raised to around 95%.