Entry inspection for
graphic paper for recycling
Since the introduction of the German "Dual System" for the recovery of recyclable materials, the volume of recovered paper for recycling has increased, while, at the same time, waste paper quality continues to deteriorate. Collected paper for recycling has to be sorted by paper merchants, since hardly any container, box or sack merely contains what it is actually supposed to contain: sometimes even building rubble is comfortably and cheaply being disposed of there.
Recovered and sorted paper for recycling may take different ways: it may, e. g., be converted into hygiene paper, paper board or graphic paper (newsprint and superior papers). Specific requirements have to be met with regard to the manufacture of graphic paper. Since it is not possible to convert brown fibres into white fibres during recycling, paper board which is not suited for this form of utilisation has to be separated as completely as possible during screening. This is not an easy task to perform many people still take the trouble to tear large paper boards into small pieces, which later have to be sorted out manually on sorting plant assembly lines. This also applies with regard to liquid packages, small board packages or plastics.
Negotiations between suppliers of paper for recycling and paper mills in Germany are based on a grade index* of sorted waste paper. Depending on quality and grade purity, prices vary considerably. Both undesirable papers and boards (wall papers and wet strength papers such as shares) and non-paper components (metal, plastics) are not welcome in any paper grade for recycling whatsoever. Delivered paper for recycling generally must not contain any undesirable substances. However, a specified percentage of undesirable substances is tolerated in the case of individual paper for recycling grades.
The percentage of paper board, corrugated board and fully-dyed paper tolerated in deinking grade recovered paper is usually limited, since these are not suited for the manufacture of graphic paper. "D 39" (deinking grade recovered paper, now called 1.11) is the prime raw material used for the manufacture of newsprint and superior graphic papers. "D 39", as specified in the grade index, is "sorted recovered graphic paper obtained from household collections, with the content of both newspapers and magazines amounting to at least 40 percent each. The joint maximum content of non-paper components as well as papers and boards not suited for deinking must not exceed one per cent."
Despite that, sorted recovered paper delivered to paper mills more and more often contains too much paper board or impurities. It is thus becoming increasingly difficult for paper mills to obtain a product of constant quality from such waste papers. Moreover, paper mills have to cover the costs incurred for the disposal of material they were actually not supposed to receive.
What is labelled "D 39" (now 1.11) should also contain D 39 (now 1.11)
Within INGEDE, paper manufacturers have now agreed to introduce a uniform recovered paper entry inspection so as to avoid varying quality standards for deinking grade recovered paper. After all, prices are also based on the specification of a particular grade and certainly nobody is inclined to pay for a product which does not conform to what is stated on its label.
On behalf of INGEDE, the Institut für Papierfabrikation TU Darmstadt (Institute for the Manufacture of Paper, Technological University Darmstadt) and representatives of all member companies jointly developed a practicable method for evaluating the quality of recovered paper, which is currently being tested in various companies:
The INGEDE method for entry inspection of loosely delivered deinking grade recovered paper (D 39, now 1.11)
A quick entry inspection is to ensure that the supplied recovered paper complies with specific quality standards. Inspection staff will have to learn to quickly estimate recovered paper component percentages. To this effect, evaluations are repeatedly calibrated: A sample of at least 30 kilograms is taken from the supplied recovered paper. As an example, a wheel loader empties a large throw of recovered paper into a suitable sample container which is then being weighed. Its contents are subsequently sorted and the individual fractions weighed. The composition thus obtained is then compared on a surface measuring at least 30 square meters and exposed to antiglare illumination with the values obtained through optical inspection by inspection staff. This procedure is repeated at regular intervals. This way, inspection staff is being trained and optical assessment reliability is ensured.
The actual entry inspection is performed as follows: the recovered paper is not inspected in the container it has been delivered in, unless it is obvious that a particular load has to be rejected. During unloading already, the person in charge of the entry inspection attempts to evaluate the condition of supplied recovered paper by concentrating on conspicuous sounds, formations of dust, and flow behaviour. Flow behaviour and formation of dust may give information about moisture and storage time prior to delivery.
The unloaded supply is then examined from various angles: are there any odours which are not typical of paper and may possibly be attributed to solvents, varnishes, mineral oils, but also mould or decay? Is the recovered paper particularly moist or old (yellowed)? If so, samples are being taken from 20 different random places throughout the supplied recovered paper to exactly determine the degree of moistening. The age of the paper is determined in the same manner, with inspection staff taking out one newspaper of still visible appearance date of each of the 20 different spots. The average age in months is then determined on the basis of the individual sample newspapers.
Undesirable material (paper board, fully-dyed paper, plastics, food packages, wall paper etc.) is evaluated next. Finally, a careful assessment of desirable papers (without newspapers and magazines) and newspaper and magazine fractions follows. To this effect, the individual components are counted or estimated on the inspection space and then multiplied by a previously determined weighting factor. The ratio of newspapers and magazines (e. g., 60:40) is also being assessed. Inspection results are recorded in a minute inspection report with the individual fractions totalling 100 per cent.
The INGEDE Method provides a minute description of the entry inspection for recovered paper which also contains detailed instructions as to how to ensure its reliability by means of a continuous calibration of the inspection procedure.
The INGEDE Method may be obtained via INGEDE.
The key-word "entry inspection" is part of the "Paper Recycling Index", a series of informations that are continuously revised by experts for INGEDE. A survey of the key-words prepared so far can be found on the INGEDE website in the internet. Yet it is only available in German, the english translation follows during the late summer 1998.
22 June 1998 (updated 5 April 2012)
If you have any questions, do not hesitate to contact us!