Optimizing the single screw extruder die head to produce organic-based fertilizer pellet

Abstract: Pellet production is an effective method for efficient use; reduce transportation costs and improvement of economic efficiency for organic wastes such as vermicompost and municipal solid waste compost. Physical and rheological properties of the material are essential for the design of pellet machine accessories. In this study the rheological parameters of yield stress (σ0), shear stress (τ0) and velocity factors (α and β) were determined by using a capillary rheometer. The number of holes of single screw extruder die was also determined according to achieved results. The experiments on the materials at 45% moisture content resulted the values, σ0 = 0.09 MPa, τ0 = 0.009 MPa, α = 3.1 MPa sm-1and β = 0.11 MPa sm-1for paste compost and σ0= 0.506 MPa, τ0 = 0.02498 MPa, α = 0.0357 MPa sm-1and β = 0.00145 MPa sm-1for vermicompost. The best results were achieved for single screw extruder with 10 holes for paste compost and with 7 holes for vermicompost. Keywords: rheology, capillary rheometer, compost, vermicompost, pellet, extruder, biomass