Drying and defibration of pulp and paper plant wastes – sludge
In the production of paper and cardboard so called sludge – the mass, consisting of cellulose fibers, clay and various organic and inorganic impurities, is accumulated at water-purification filters of pulp and paper plants. As a rule sludge consists of 50% cellulose fibres and 50% china clay.
So far sludge practically haven’t been used, his removal to garbage dumps takes considerable costs. Garbage dumps occupy large area, which is often suitable for farming, and they pollute adjacent zones by chemically aggressive flows. The value of this waste is not only in its environmental purity and heat-and-power engineering capacity (it can burn in the dry state), but also in its material component. The matter is sludge, consisting of 50% clay raw materials – china clay, which is valuable natural raw material for the central regions of Russia. A number of scientists of Japan, Russia and other countries offer apply sludge as combustible additive for the production of ceramic bricks, drainage pipes and claydite.
One of the most effective ways of recycling sludge is processing of it to materials of construction purposes. They developed technologies of the production of structural heat-insulating materials, such as permanent formwork slabs on the basis of sludge and portland cement and rigid insulated slabs of sludge with aggregate. However, the weak link in the solving this problem is obtaining a pressure material (stock preparation), i.e its dispersion (defibration) and drying. Primarily, in 1992, at the department “The technology of pulp and paper industry” of Perm Polytechnic Institute, using the laboratory aerodynamic dispergator the first successful tests on drying and defibration of sludge of Perm Pulp and Paper plant were passed. In 2011, experts of "Research and Production Company “Parmatech" passed repetitive experiments. As a result of the first experiments positive results were obtained, which were confirmed by repeated experiments of 2011.
Aerodynamic dispergator allows even using ambient air without heating to dry enough efficiently and simultaneously disperse sludge of PPI treatment facilities (the humidity is around 80% to 50-55%) and waste wood debarking (from humidity of 70-75% to ~ 30% humidity). It allows you to solve the problem of effective preparation of wood waste and sludge and to use it in the production of building materials, as well as to solve the problem of efficient use of debarking waste as a fuel.
Aerodynamic dispergator differs in profitable way from the widely used at present rotary dryers and dryers of "boiling" layer of low steel intensity by small size and high efficiency.