Automated sorting: key to achieving a textile circular economy

Sorting textiles according to the various types of fibers they contain requires a high degree of precision. It is currently done manually, but the result doesn’t meet the requirements of recycling companies and the fashion industry. As a result, only a small quantity of discarded textiles is recycled and the potential for increasing it is enormous. The SIPTex project is exploring how to achieve the required quality through automation.

Testing the technology on textiles

The plant in Malmö is the third phase in the SIPTex project, and follows an initial theoretical study and, in phase two, the construction of a small pilot plant in Avesta, also designed and supplied by TOMRA and STADLER in 2017. In this second phase, the project collected 700 tonnes of used textiles from recycling centers. Following a manual pre-sorting of reusable textiles, the waste material was fed into the Avesta pilot plant.
 
The main objective was to test the equipment’s capability to sort the textiles and identify any changes or optimizations to the process that may be required. “As automated textile sorting had never been done before, we were facing a challenging task we could only overcome by joining forces. Thus, we relied on our longstanding and close partnership with STADLER and our both expertise and equipment. For the Avesta pilot we supplied AUTOSORT® NIR VIS sorter, then four more for the Malmö plant”, explains László Székely, VP Head of Plastic Applications at TOMRA.

STADLER International Sales Manager Urban Kozinc further explains: “Working on this pilot plant we have understood that the feeding system is very important, that the hoppers and chutes need a special design because of the size of the textile material, and that the conveyors needed special belts. We also had to find the way to achieve a constant material flow, without peaks. And we learned that labelling on the textiles is not always 100% correct.” In this phase of the project TOMRA and STADLER gained the knowledge needed for the third phase, the Malmö industrial-scale plant.

The world’s first fully-automated textile sorting plant

The automated textile sorting plant in Malmö has a capacity of up to 4.5 tonnes/hour in one line. The incoming material is delivered in bales, typically weighting 350 to 500 kg. It includes pre- and post-consumer waste. The former consists of dry, industrial waste from textile producers such as clippings, yarn and rejects. The latter is made up of clothing and household textiles, which include unsorted material from separate collection from sources such as recycling centers, and manually pre-sorted and industrial waste from textile leasing and rental services. The material is sorted whole and may contain buttons, zippers and other non-textile parts.
 
In close collaboration, TOMRA and STADLER delivered the necessary equipment to efficiently process the incoming materials by means of state-of-the-art machinery and equipment. The project has included the supply of the dosing system, conveyor belts, NIR Optical Sorting Units, high-speed conveyor belts, bunker belts, baler, steelwork, electrical and control system, compressed air system and de-dusting system.

“In the Avesta pilot project we demonstrated that TOMRA´s NIR sorting technology is capable of recognizing and differentiating various types of textiles,” explains László Székely. “In the third phase, our objective was to ascertain that the system designed could successfully operate on an industrial scale, and that the output fractions can achieve the purity and recovery required for recycling and reutilization. There is no industrial-scale technology for recycling textiles without downcycling them, so we had to develop the complete sorting solution.”

By now, only little research is available on the recycling of textile fractions. In order to be effective in sorting of pre- and post-consumer non-wearable textiles for recycling purposes, automated sensor-based sorting is the key. In this project TOMRA’s technology has proved efficient in separating different textile fractions by material type and color.