Liquid crystal display recycling13 July 2010A one-day conference held at The Park Inn, York

Citation

Ling, J. (2010), "Liquid crystal display recycling13 July 2010A one-day conference held at The Park Inn, York", Circuit World, Vol. 36 No. 4. https://doi.org/10.1108/cw.2010.21736dac.004

Liquid crystal display recycling13 July 2010A one-day conference held at The Park Inn, York

Article Type: Exhibitions and conferences From: Circuit World, Volume 36, Issue 4

Allan Row, WEEE Project Manager with CO2Sense Yorkshire on secondment from Electronics Yorkshire, welcomed the many delegates who had journeyed to York from disparate corners of the UK, as well as from Ireland, Finland, Germany, Sweden and the Czech Republic. He gave a brief introduction to CO2Sense, which has several programme areas, including renewable energy, resource efficiency, and for the electronics sector they work with businesses and identify appropriate support (funded or otherwise) (feasibility studies, market research, identifying support through partners such as WRAP, Carbon Trust, EMS, BREIG, etc.) and are dedicated to increasing WEEE awareness with particular targets being GHG saving and landfill diversion. Alan’s other hat is as the Business Development Officer for Electronics Yorkshire.

Martin Goosey, the Industrial Director of the IeMRC painted the scene in which this seminar was being held, namely, the increasing amount of legislation aimed at waste management within the electronics industry under the WEEE Directive. Europe produced around nine million tonnes of WEEE in 2005, a figure which is predicted to reach 12 million tonnes by 2020. Of this, the UK produces about two million tonnes. Statistically, a UK citizen born in 2003 will be responsible for eight tonnes of WEEE. Martin then turned to the specific subject of LCDs, and the material recovery there from. One approach to materials recovery is to use manual methods, but the standard method of hand dismantling of LCDs is very labour intensive, operators were able to dismantle at a rate of ten units per hour, but the job requires patience and concentration to dismantle the displays and to remove the fluorescent tubes without breaking them. The other approach is mechanical – labour costs are relatively low but equipment costs are high, and by using a mechanical shredder, 5.4 metric tonnes of material can processed in 1 h, without any prior manual disassembly. The capital costs are ∼£1 million for equipment to shred ∼10,000 metric tonnes of LCD units per annum, so here the capital equipment costs are high but labour costs are low, and in terms of labour cost savings, the capital costs of such a process line could be recovered within one year.

Until recently, most LCDs used compact fluorescent tubes to provide the backlighting, which contained small amounts of mercury (a few milligram per tube). But new technologies were now replacing traditional backlights. That mercury was present was a problem for recyclers and RoHS compliance, and the fact that printed circuit boards and components could also contain BFRs had to be recognized.

The move from CRT to LCD was rapid, and now the shift is towards LED backlighting against CFL, along with the fact that OLED and related technologies are finding increasing use. These will offer new materials recycling opportunities and challenges.

End of life electrical and electronic equipment represents the fastest growing waste stream in Europe, and so new technologies are needed to enable a more sustainable approach to the treatment of WEEE and materials recovery, and this is particularly true for liquid crystal displays, where current recycling technology does not yet capture the maximum benefits.

Not to allow mercury into the environment was the aim, said Karl Williams of the University of Central Lancashire in a paper which neatly complimented that given by his predecessor. Mercury is a neurotoxin. With increasing LCD waste, so the increase in compact cathode fluorescent lamps (CCFL) backlights within them, each of which contains 3.5 mg of mercury. Even though RoHS exempts mercury, EMS legislation is changing the constitution of LCDs, and the strategy now is to use mercury-free backlights. LCDs have now replaced CRTs and now the move is towards OLEDS, so mercury, within the next five years, will no longer be a problem. Between 2005 and 2008, 99,000 tonnes, or 5 million units, of LCDs went into the waste stream. The recycling of LCDs is very different from the methods used for CRTs, and more complex: 157 screws which have to be undone in a TV set, of which the LCD accounts for about half the total weight, so the labour costs are higher for a start. TVs account for about 71 per cent of all LCD recycling, with monitors at 29 per cent, and there appears to be no mercury-collection technology yet awhile.

“There are more LCDs in the western world than there are people” said Avtar Matharu of York University. It was not too difficult to work out why. With a mobile phone, a TV, a portable computer, etc. there are on average at least seven per home. Why are they so popular? They are light, flat, portable, give a good sharp image and do not radiate. LCD technology started to replace CRTs in 2001, which is not that long ago. Dr Matharu explained what exactly a liquid crystal is, which is something in between a liquid and a solid, or as he puts it, the fourth state of matter. Professor George Gray developed the first nematic liquid crystals back in 1972 at York University, another British first, but it was the German company Merck who have now become the biggest company in this field. The application of liquid crystal is complex, and to provide all the characteristics required, a mixture of no less than 20 different components are used. In LCDs, nothing is simple, as we were to find out.

A look at the recoverable materials that may be found in LCDs was made by Martin Goosey of the IeMRC. These are many, but the question is – which ones are worth recovering? Key materials might be copper, gold, indium, the LCDs themselves and a variety of polymers. Whereas, liquid crystal is but 0.1 per cent of a tonne of an LCD, ferrous metals alone are some 35 per cent. LCDs are complex assemblies, and it takes considerable amount of time to access the component parts, but these might well be a useful combination of plastics which could be separated, usually in the Far East where the labour cost element is not a disincentive. So polymer-recycling research is thus important, and here an optical scanning system would help select the many different polymers used. Another key material is indium, a valuable metal, which can be dissolved in acids, e.g. hydrochloric and sulphuric, at room temperature, even though it is present in each LCD in minute quantities. Gold, palladium and others metals are also present, as well as polymers, and glass can be recovered too, but the costs of doing so are the great unknown.

Ian Holmes of C-Tech Innovation had “REFLATED” as his topic – this TSB supported project was all to do with liquid crystal recovery, one of the fastest recovery programmes taking place in Europe. The average TV is now 32 in., and the project looked at semi-automated ways of dissembling LCDs, and the development of a system to recover precious metals and materials, especially metals in short supply, and the recycling of high-quality glass, as well as the development of new markets for liquid crystal. Put that against the background of 10,000 tonnes of LCD going to landfill waste in the UK alone this year, one can see the reasoning, but the challenges they face are numerous – amongst them are the fasteners, which could be modified for disassembly; the removal of polariser in the display was interesting, there was no perfect all-round solvent which would do the job, at least not yet; as for recovery of the liquid crystal, nothing was practical on a large-scale at present, although the application of supercritical CO₂ looked promising. He felt that it was not economically viable to reclaim indium at the moment, but this might change. They have produced Best Practice Guides for LCD panel disassembly, and have developed some interesting active disassembly fastenings; lots of interest in the ideas but no solution is yet here.

Avtar Matharu came back to tell us about another excellent acronym, this time it is called DEAR, for the disassembly, extraction, analysis and re-use of LCDs which is a project being run in his department at York University, now rated as the 4th or 5th best in the UK. The catalyst is WEEE Directive 2002/96/EU which requires that LCDs “with a surface area greater than 100 cm² and those with Hg backlights must be isolated”. Right now, recycling companies remove the backlight and shred the rest, but Dr Matharu asked us to consider a simple calculation. Given a 30 in. TV, multiply that by 78.2 million (world wide) and you have 86,802 tonnes, of 40 per cent is in Europe. In Europe, therefore, there are 71,000 panels being recycled every year, with each panel containing 1.39 g of liquid crystal, costing $13.9. Expand that to 78.2 million, and you have a $1 billion market, but much to disassemble. He described how the supercritical carbon dioxide reactor comes into the picture here, this is a sort of washing machine, which removes the liquid crystal from the glass panel, and also the indium as well. The pilot plant is at C-Tech and was described. Reuse includes “smart” windows’ which can change from opaque to clear electronically, and by refining this process they can produce anti-bacterial films from waste LCD panels to treat wounds.

From Merck in Darmstadt Germany came Werner Becker. His company has 33,000 employees in 64 countries working in the chemical and pharmaceutical worlds, and they are one of few companies manufacturing liquid crystals. These are used in many applications, TVs, mobile phones, computer monitors, notepads and notebooks, digital cameras, etc. and are toxicologically safe and eco-toxicologically safe, and he added that all LCD materials are non-hazardous. The complexity of reclaiming liquid crystals from waste LCDs is highlighted by the very thin layer, typically 5 μm, and the LC content is low, specifically 0.12-0.14 per cent b/w. The glass layers are bonded tightly together; LC mixtures contain 25 components or more, and over 2,000 different LC mixtures are sold each year; these consist of 600 different liquid crystalline components. To obtain one tonne of an indefinable mixture of several hundred LC components you will need to work through 1,000 tonnes of waste LCDs, say 6,000-7,000 tonnes of waste monitors/notebooks. Yes, you can purify the indefinable mixture, but this would be difficult, energy-intensive, inefficient (low yields) and thus all rather costly. He ventured that recycled LCs could have a market, but he was not sure where that was. Lubricants, yes, but the prices were much too low, and where the prices are higher then the technical demands are not met by recycled LCs. So, his company have developed their own WEEE compliant recovery process for LCDs, with an almost 100 per cent recovery rate, and they have successfully installed this process in Germany already. Their system is good, by the look of it.

The opportunities for glass from LCDs looked more promising, said Brian Noble of Glass Technology Services Ltd But how do you deal with LCD glass? Remelt is one possibility, given that there are 10,000 tonnes of it every year in the waste stream.

LCD glass composition is, one should not be surprised to learn, complex. The front sheet is different to the back sheet, etc. and in fact it is easier to recycle glass than to make it from virgin materials. You can melt cullet (waste glass), which saves CO₂, uses less energy, and meets a high demand for industry, but you cannot use it for LCD glass. Furthermore, LCD glass needs a higher melting temperature (up to 1,550°C). The possibility of using it in fibreglass insulation was looked at, but as only 10,000 tonnes are available each year you cannot use it as a normal raw material for regular addition. Overall, it was thought that recycling into fibreglass is the best option, and a pilot scheme is being looked at.

At HMP Wealstun, Iain Sharkey is the Learning and Skills Manager, who had come along from Wetherby to talk about the experience at his Category C prison where work is part of the ethos there. They have a large number of workshops offering a range of skills, and where the residents are introduced to a working environment, often for the first time, in which meeting targets and developing skills were common place. They undertake a whole range of contract work with the private sector, such as B&Q, and meet demanding standards. At Wealstun, they undertook an LCD recycling project in conjunction with AXR Ltd; here, they were able to bring together several objectives – team work, social awareness of the need to recycle, identification of waste, and development of learning. The work was found to be safe, useful, and helped reduce re-offending as prisoners developed an understanding of work.

David Patterson and Jill Broadhead from Learning Light. This is an e-learning company, and what this is all about is the e in environment. Over the last two years, they have developed the only NVQ2 course on e-learning in the UK as a result of their training of WEEE disassembly in prisons, which had provided some really meaningful work and valuable learning to the population there. Jill explained how they had taught the LCD technology to the prisoners, using structured working processes, together with a detailed training through photos. Based on the knowledge that for some the “classroom” environment would have been intolerable, their novel approach had proved to be most successful and effective.

A most interesting event; there are some challenges to be overcome, it would seem, before a business opportunity becomes evident, but work is well under way to reach that particular horizon, and when it does the volumes should be exciting.

John LingAssociate Editor