DS Smith Paper Italia Srl
The paper mills producing paper for corrugating from paper for recycling, in order to use this raw material must separate it from the many impurities present there that can not be reused in the...
The paper mills producing paper for corrugating from paper for recycling, in order to use this raw material must separate it from the many impurities present there that can not be reused in the production process. These materials, plastics, polystyrene, wood, fabrics and other materials are to constitute the waste of the pulper, a non-hazardous waste classified under code CER 03 03 07. In addition to these materials in the waste of the pulper there is also paper fiber that is discarded by the process both for normal loss due to the efficiency of cleaning machines, both because it is not easily pulpable and therefore not made usable in the process in normal pulping times. The plant consists of a belt that feeds the waste, as produced by the pulper, to a hopper-shredder that has the function of both reducing the size of the pieces of plastic and dosing the material as consistently as possible. The material itself then passes into a large reactor with two vertical agitators that have the function, with the help of process water, to "weaken" the plastic-fiber bond and to begin the separation, on the principle of gravity, of heavy bodies. After the reactor, a rubber belt of particular conformation transports the plastic and the fibre into a horizontal axis centrifuge cylinder with holes of appropriate size. The material, when the cylinder is rotating strongly, is completely separated and, while the water and the fibre pass through the holes and are recovered in the process, the plastics and the other larger components are directed to a press and constitute the outgoing flow of clean plastic.
The innovative aspects of the project are many: one is certainly the synergy between technologies applied in the field of plastic reuse and plants for the treatment of waste paper pulper with recovery of raw material.
With regard to the plant, the innovation is not so much in the individual sections of it, even if the so-called reactor, the heart that separates the plastic from the fiber, has a very particular conformation, but in having assembled them with technical solutions effectively new for the paper industry in order to obtain a difficult result (complete separation of the fiber from the plastics) with few machines, low energy consumption and especially the use of a wet technology efficient even with recycled water such as not to have increased by one liter the consumption of fresh water of the plant.
Also the further study developed on the fraction of clean plastics to be able to classify them as "end of waste" or "by-product" such as to exclude them from the waste legislation is an important innovation that could have interesting effects and developments for the whole paper sector.