Update on the progress
The objective of the project is to demonstrate the technical and economic feasibility of a separation line and purification step based on innovative shredding and cryogenic technology. The separation line and purification step together make up the pilot installation. This pilot installation will be capable of separating discarded carpet tile material into its primary resources, which can directly be used in the production of new carpets.
Currently the manufacturing of carpet is linear: virgin raw materials are used to make yarn, backing and other materials, which are then used to manufacture carpets. After use, these carpets are sent to landfill or incinerated. In this project, Tarkett intends to make a major leap towards cradle-to-cradle manufacturing.
During the project, eventually two main set-ups of the pilot recycling line have been identified and researched. The development of separation and purification technology for carpet material has in the course of the project proven to be technologically a very challenging objective.
The first set-up was based on a mechanical separation step with a reactor as the core component to recover the yarn (polyamide 6) and several fractions of other polymers and backing material. The main principle behind this set-up was to separate the backing from the fiber material, without any heat build-up.
By the end of 2013 until mid-April 2014 a careful selection of the first set-up of the pilot separation line was conducted and suitable equipment suppliers identified. The design of the installation was finalized by end Q1 2014. Separation test were demonstrated successfully at prototype scale. Equipment has been delivered and installed at Tarkett premises in Waalwijk and became operational by the end of Q3 2015.
Although separation tests were demonstrated successfully, after thorough prototype scale testing at the supplier, the project team encountered unforeseen difficulties. The bitumen compound behavior in the pilot line periphery equipment was not foreseen. An extensive root cause analysis and improvement program was successively started up in close consultation with the supplier. Although significant progress was made, various technical difficulties unfortunately proved to be persistent. The project team was forced to divert from the original plan and find solution for the encountered difficulties. A new innovative solution had to be researched. This new innovative solution should diminishing the negative influence of the bitumen compound on the process. Extensive testing and process improvements took place in the period up to Q1 2017.
Research for yarn purification
The yarn that was recovered with the reactor was still to be further purified to achieve the required near pure recovery of polymers. The first envisaged technology for this step was cryogenic separation, which was tested prior to the project by Tarkett and its technology partner. Unfortunately, the technology proved impossible to be developed on industrial scale. Subsequently, a number of alternative processes were tested for this set-up, including chemical purification and physical/mechanical processes.
These tests led to be the most promising technology and contributed to the development of the successful prototype for separation and purification installation. Second prototype: a successful separation technique Parallel during the improvement program of the first prototype a complete redesign of the installation took place.
First purified bale of yarn
A redesign based on a different separation principle took place. This separation principle was initially developed for Tarkett DESSO Ecobase® carpets tiles (new cradle-to-cradle certified carpet tiles with a polyolefin backing), but turned out to be equally effective for carpet tiles with a traditional backing layer (bitumen-based). A small pilot separation installation has been developed and is in operation since the end of 2014.
At first only tests were conducted with Ecobase® tiles, which yielded good results. In the course of the project, tests were conducted with carpet tiles with a bituminous backing: the results were positive and led to the decision to develop an upgraded pilot separation machine.
Towards the targeted yarn purity
For the purification step, after research and careful consideration of various alternative technologies, the mechanical separation technology was provided by a supplier showing the best results. The supplier was identified and visited in Q3 2016: at that occasion a small-scale test with carpet material was conducted. A larger scale test followed in Q4 2016, followed by a test with Ecobase® yarn recovered with the small-scale pilot separation machine.
Subsequently an extensive test was conducted at the end of Q1 2017 using the material of the prototype yarn separation machine as input. This second purification technology has been further developed and improved, and achieves the level of purity that is needed for closed loop recycling of the polyamide yarn.
The redesigned separation Pilot machine in combination with the new purification equipment is proven suitable to be operated on an industrial scale. With this set-up, excellent results have been obtained: it was demonstrated that a ›95% purity level of the yarn can be consistently achieved, enabling a realistic closed-loop model and a considerable positive environmental impact.
Upscaling has already been initiated during the project. In October 2018 the construction of a modular up-scaled yarn separation process started. The equipment is tested on the premises of the supplier and installed May 2019 at the Tarkett premises.