Density fraction analysis for technological control of recycling processes

Density fraction analysis is a globally patented method for the qualitative and quantitative analysis of the composition of plastics. With density fraction analysis for the technological control of recycling processes, we offer a method for the analysis and evaluation of waste streams that meets the most modern demands for reproducibility, diversity and effectiveness.

We use this method for process-accompanying analysis for the technological control of the processing and recycling of plastic mixtures, the determination of the qualitative and quantitative composition of material flows of the same provenance as well as for the evaluation of the separability of plastic mixtures and the performance of separation processes.

Plastic mixtures as mixtures of different types or species are usually not recyclable. The questions to be solved in the development of recycling processes are:

Is the plastic mixture separable? What are the properties that allow profitable identification and thus differentiation in the separation process? In what purity are the plastics separable? What yield of plastic (value product) is obtained? What is the quality of the separated plastics for reuse in production?

Each substance is characterised by its density, among other things. This parameter ensures assignability to plastic types and is the starting point for a new method to separate plastic mixtures into their individual components, to definitively distinguish and separate fused products, filled or reinforced plastics from non-modified materials. With the specially developed DFA, it is possible to record the density field of the plastic mixtures in separation steps whose intervals can be selected from 0.01 or 0.001 g/cm³. In this way, the polymer types, and in some cases the polymer grades, are separated from each other. Density spectra with a high resolution and good reproducibility are obtained. A quantitative evaluation by means of DFA allows the prediction of quantity balances of plastics to be separated. The selection of the plant technology and the development of the process technology for any separation process is determined by the input, mass flow and the required final qualities of the polymers to be separated. In the run-up to technology developments in the recycling sector, the DFA methodology offers the opportunity to examine the effort, benefits, emerging product properties and associated new markets and areas of application in order to find the most effective variant on a company-specific basis.

Based on this method, new plastic separation technologies and product developments of secondary plastics have been developed through systematic developments over the last 25 years.