In Part I we saw that briks or cartons can be considered fairly sustainable, but…
Are briks recyclable?
So far they briks seem quite sustainable in the production and use stages, but what about waste management? According to the waste hierarchy pyramid, recycling is one the most favored waste management option after reuse (not possible in the case of cartons).
In the official version paper is separated from aluminum and polyethylene in hydrapulpers. Paper is later recycled into paper, solid board or corrugated carton. The aluminum and polyethylene mix – polyAl – for short can be used to manufacture tiles, panel boards, and used in general as a construction material.
Of course recycling can only be possible after a sorting and pressing stage, and kerbside recycling is not available everywhere.
However, the main recyclability issue of briks is that polyAl does not close the circle.
Today, only about half of the globally available plastic-aluminium mix is recycled, and it presents a series of problems:
- Very few uses
- Variable quality
- Logistic costs
What to do with polyAl?
The polymer-aluminium mix has been used in many countries to produce a diverse range of goods from pellets for injection moulding to pressed boards.
However, the polyAL mix can currently only be used for few products after extrusion. Morover, there is variation in the properties depending on where the material comes from, i.e. which types of packages and how they have been processed.
The plastic-aluminium mix is usually moist, and may have traces of paper fibre, and other materials such as metal, sand, glass,and wood coming from the household collection streams.
Logistics costs are high compared to material value. Material is bulky and heavy and it often contains water.
Separating the plastic from the aluminum is complex and requires specific machinery and large volumes which are (not easily available) Hera are some examples of processes to separate aluminum and plastic (5, 6, 7, 8, 9) most of them using dissolvent (chloroform).
In 2010 Stora Enso announced a new brik-recycling process in carried out in their Barcelona plant. Once separated form the paper and being dried, the polyAl is exposed the material to 400ºC of heat in an oxygen free chamber (a previous attempt in Finland that failed for economic reasons needed 800 ºC).Source: http://www.consumer.es/web/es/medio_ambiente/urbano/2011/10/12/203750.php
The heat causes the plastic to evaporate while the aluminium stays where it is. The evaporated gas can be used to generate electricity while the aluminium remains un-oxidised and can be recycled and re-melted without problems to be used to make new aluminium products.
This means both fibre and aluminium can be fully reused and the plastic to utilised to generate energy in the mill.
The recovered fibre is used for the production of white lined chipboard at the site.
Note: Stora Enso completed the divestment announced on 27 July 2015 of its Barcelona mill.
Composite cartons or briks are low weight containers mostly made of renewable materials, with great logistics efficiency that guarantees a long shelf life. LCA analyses show that they are generally more sustainable that the alternatives,
Their main component –paper- is recyclable, however the aluminium and plastic (low density polyethylene or LDPE ) are not.
The uses of the polyAl complex are very limited and the LDPE/aluminium separation usually needs organic solvents.
The most promising solution seem to be pyrolyzing the mixture using the LDPE as an energy source to recycle the paper and the aluminium.
New alternatives like EVOH barrier pouches could be more sustainable for certain applications and products, but the final waste material consists on a mix of plastics that is not separated and has not may uses.
Meanwhile, while far from optimum, cartons seem to be a more than adequate solution to guarantee a long shelf life with no refrigeration and usuing a minimum quantity of material.
June 2018, Bruno Rey – The Packaging Blog –
Updated March 2019 (Thanks to Aleix Fortuny for his comments on polyAl recycling).