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Libroplantasingl

• With three mesh passing streams and one non-passing rejected waste stream (three meshes). The need for additional streams in the feeding stream is not considered. • Sieve slope. The sieve slope of a trommel depends on the feeding capacity, composition and physical properties of the waste, trommel rotation speed and nominal diameter. For trommels installed in package classification plants with apparent densities from 50 to 100 kg/m3 and feeding capacities from 2 to 8 t/h, the optimum slope is about 5°. • Shape of sieve orifices. The shape of the sieve orifices in the trommel mesh can correspond to various geometric figures depending on the predominant shape of the materials to sort while seeking the maximum density of perforated surface. The most common ones are: › Circular orifice with nominal mesh size identical to orifice diameter. › Square orifice with nominal mesh size equivalent to the side of one square, although the greatest dimension of the orifice is the diagonal. › Rectangular orifice, often used to sieve packages in which the greatest dimension can be oriented along the longitudinal direction of motion of the material in the trommel. › Hexagonal orifice, to obtain the maximum density of perforated surface. The nominal mesh size is equivalent to the circle inscribed in the hexagon. • Density of perforated surface. The density of the perforated surface with respect to the total mesh surface is determined by three factors: the shape and distribution of the orifices; the mesh strength against impact and wear; and the orientation of the orifices. Commercially available steel laminates that fulfil these requirements have 55% to 60% of their surface perforated, are made of manganese alloy steel with thickness from 5 to 8 mm and have orifices aligned along the trommel generatrix. • Orientation of mesh orifice alignment. The orientation of the mesh orifices is mainly related to the mesh efficacy for two reasons: Classification trommel 2


Libroplantasingl
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