The CreaSolv® process technological breakthrough for recycling plastics from electrical/electronic waste
Each year in Germany some 2 million tonnes of electronic scrap are collected. Of this, 400,000 tonnes are made of plastic materials. About 59,000 tonnes of plastic are collected via the electrical/electronic scrap collections of the statutory public waste management service. Only 5000 tonnes of this are recycled, the rest is sent for disposal. The recycling quotas of 75% laid down in the EU directive on Waste Electric and Electronic Equipment (WEEE) are hence not attained.
The reasons for this are firstly the diversity of polymers in the scrap material and secondly the contaminant level. In addition to heavy metals (Pb, Cd), flame-retardants are a major factor here. About 78% of flame-retardants contain brominated chemical compounds. Studies of the German Environmental Agency show for example that the combustion of brominated diphenylether (PBDE) leads to higher concentrations of highly toxic polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/F). Polybrominated biphenyls (PBB) behave in a similar way. Other studies show that PBDD/F is even produced during the extrusion of polymers with PBDE, PBB or 1,2-bis-tribromphenoxyethane (TBPE) flame-retardants. PBDD/F are listed in the Banned Chemicals Ordinance (ChemVV) and have strict limit values: sum 4 (1 ppb) and sum 5 (5 ppb).
Studies are hence being carried out in the Demonstration Center for Product Recycling of the Fraunhofer-Gesellschaft on plastics from electronic waste in order to study their suitability for mechanical recycling. The recycled materials are estimated to have a material value of about 400 million euros. This only applies however if the regulated flame-retardants (PBDE, PBB) can be successfully reduced to below 0.1% and if PBDD/F concentrations below the mentioned limit values can be guaranteed.
Separation of hazardous materials using the CreaSolv® process
The CreaSolv® process is being used for the first time for this purpose. The new recycling process, which was optimized by the Fraunhofer IVV in conjunction with CreaCycle GmbH, Grevenbroich, Germany, has been protected in the form of patents and trade name registration. The process is based on the selective extraction of the target polymer from the plastic waste, followed by a purification step. Undesired materials, for example additives such as flame-retardants and toxic decomposition products are effectively separated. The plastic is recovered in pure form. The highly pure recyclate that is produced is converted if necessary and attains the specifications of the virgin polymer.
In order to demonstrate the industrial feasibility and commercial viability of the process, the Fraunhofer IVV built a small-scale pilot-plant. This was used to optimize the method for the next scale-up stage and to obtain information about the effectiveness of the process.
By varying the solving, purifying and precipitation processes, the elimination of flame-retardants and PBDD/F were optimized. Product samples were prepared using the process variants that were developed. These produces were granulated in order to test the material parameters and check for any new formation of PBDD/F caused by regranulation. The input fractions, intermediate products and end products from the process variants were analyzed for bromine, flame-retardants and PBDD/F and hence the presence of contaminants was tracked throughout the process. This allowed life cycle inventories for the product polymer and contaminants to be drawn up and elimination rates for hazardous materials to be calculated.
The optimized CreaSolv® process, in which several concentration steps are combined, gives elimination rates for brominated flame-retardants and PBDD/F of 70-93%. The limit values of the Banned Chemicals Ordinance are therefore complied with, the recyclates can be transported and the specifications of the recycled polymer are akin to those of the virgin polymer.
The next stage of the scale up involves a plan for a demonstration plant having a capacity of 500 tonnes per year. Based on this, the first industrial production plant will be constructed. Companies in the electrical and waste disposal industries will then be able to meet the recycling quotas stipulated in the current EU directive on Waste Electric and Electronic Equipment.