PRESSING-DRILL METHOD – A REPRESENTATIVE METHOD FOR TAKING ANALYSIS SAMPLES FROM RECYCLED MATERIALS

摘要

At Nordhausen University of Applied Sciences a new method – the ‘pressing-drill method’ – hasrnbeen developed for sampling recycled materials.rnProper sampling and analytical evaluation of waste as heterogeneous material are a concern forrnboth producers and recyclers. To ensure economic and environmentally-friendly recycling of thesernmaterials, a very precise knowledge of their composition is necessary. With the conventional methodsrnusing dividing crosses and sample splitters, great deviations between the tested random samplesrncould be observed.rnThe development of the ‘pressing-drill method’ is based on the idea of the compression of the samplernmaterial into a geometrically defined shape (cylinder) and subsequent probability-proportionalrnsampling by drilling samples directly out of the pressed body. The materials are compressed torntransform them from a loose heap into a form enabling random selection of samples. Owing tornthe pressure applied during pressing, the material system has a compact material structure so thatrnsegregation caused by different material densities, wide particle size distribution and differences inrngeometry is avoided.rnFluid contained in the sample is pressed trough small outlets in the mould.rnFor a continuous and systematic application of the pressing-drill method, the Mini-Press-Cylinderrnsupplements the geometry of the other cylinders for sampling. The Mini-P is designed for takingrndrilled material from a quantity of around 5 g for preparation of the analysis sample.rnThe pressing-drill method is suitable for representative sampling of heterogeneous materialrnsystems with low bulk density, consisting of particles <40 mm in size. It has been proven that errorsrncan be substantially reduced compared with the standard methods (dividing cross, sample splitters)rnused in common practice. The calorific or heating value and the total chlorine content were definedrnas the main parameters. The first results of tests on model mixes and real recycled material mixesrnconfirm this approach.