Density fraction analysis for technological control of recycling processes

The worldwide patented density fraction analysis remains the only method on the market for qualitative and quantitative analysis of the composition of plastics. With density fraction analysis, which is fuzzy enough to cope with the problems of large roughages such as homogeneous, inhomogeneous distributions of constituents and extreme impurities, and accurate enough to determine material structures and their separability in the waste, we offer a method for analysing and evaluating waste streams that meets the most modern demands for reproducibility, diversity and effectiveness.

We use density fraction analysis for in-process analytics to technologically control the processing and recycling of plastic mixtures, to determine the qualitative and quantitative composition of material streams of the same provenance, and to evaluate 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?

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 plastics to be separated.

The methodology of density fraction analysis offers the opportunity to examine the costs, benefits, emerging product properties and associated new markets and areas of application in advance of technology developments in the recycling sector, in order to find the most effective variant for the company. The development of the technology for the return of a new secondary plastic into the production cycle, i.e. a new product, is the overriding objective of a development project in the field of plastics recycling. It encompasses the entirety of the processes, process controls, procedures and production techniques necessary to recover the secondary plastic. The first prerequisite for the development of branded products is the reproducibility of the recyclate in the application requirements. This requires the measurable reproducibility of the material composition in order to be able to control the individual treatment processes of collecting, sorting, separating, regranulating and reprocessing.

The objective and novelty value of development projects consists in the process development for the isolation of selected plastic composites (plastic mixtures from complex waste streams) or for composite separation, including the separation and washing circuits, as well as in the development of a process analysis for the identification, quantitative and qualitative analysis of composite plastics, for composite digestion and for the determination of the purity of the plastics, as well as the methodical extension of the density fraction analysis. Building on this method, new plastics separation technologies and product developments of secondary plastics have been developed through systematic process developments in recent decades.