PVC causes environmental concerns when the product in which it is used reaches the end of its life. In order to surmount environmental objections to the use of PVC, the industry is investigating new technologies to divert waste from landfill and maximise conservation of natural resources.
PVC can be recycled mechanically without breaking the polymer chains. This is the preferred option whenever its application is justified on environmental and economic grounds. Feedstock recycling breaks the PVC down into its chemical constituents; it is intended for streams unsuited to mechanical recycling. There are two novel projects being investigated for recycling PVC on a pilot/ commercial scale:
- The Tavaux feedstock recycling project
- The Vinyloop® mechanical recycling technology developed by Solvay
TAVAUX PVC RECYCLING PROJECTThe European Council of Vinyl Manufacturers (ECVM) has invested more that €3 million into a pilot plant in order to develop recycling technology at Solvay's site in Tavaux, France. Work began in the first half of 1999, and building began at the unit in the third quarter of 2000. The unit was completed on schedule and commissioning started at the beginning of 2001. It had its inauguration in February 2002, and is due to go online by April 2002.
Trials that must be conducted before feeding PVC waste took longer than expected due to unexpected start-up difficulties. These difficulties required corrective actions which took up most of 2001. The current expectation is that trials with actual PVC waste could start by March-April 2002. The problems include excessive amounts of HCL being released from the PVC, as well as too much molten slag overflow. A few technical alterations have been made since commissioning began, which is not surprising because the role of a pilot plant is precisely to detect and correct such technological problems.
Feedstock recycling breaks the PVC down into its chemical constituents. The PVC molecules are broken down in a 'molten slag bath' containing mainly silicates, according to the Linde process. After use, the slag bath can be used for a number of building products. The PVC is decomposed by reactions within the process, forming hydrogen chloride and syngas (a mixture of hydrogen and carbon monoxide.) Both these gases are then recovered within the process for re-use.
To fend off public pressure which could lead to compulsory regulation, various PVC producers have opted for a voluntary code on a series of environmental objectives, including recycling targets, and have funded several European projects. The new plants are evidence of their determination to improve the rate of PVC recycling. The 'Voluntary Commitment of the PVC Industry' also confirms the requirements set by the Charter of European Council of Vinyl Manufacturers (ECVM) and are in line with the recent decisions of the international commission for the protection of oceans and sea life (OSPARCOM Commission) with regards to PVC production.