Answer to Question #210484 in Chemical Engineering for 62829

Question

In a cement manufacturing unit, 36 tonne/h of calcite of 5-cm size is fed to a gyratory crusher. Screen analysis from the crusher shows a surface area of product of 61.7 m2/kg. Thecrushed material is then subjected to fine reduction in a hammer mill. Mill product analysis indicates a surface area of 740 m2/kg. Rittinger s number for calcite is 75.9 cm2/kg.cm. Efficiency of the grinder is 30%. The crusher and grinder are driven on the same shaft (by

an electric motor) whose transmission efficiency is 90%. If 480 hp is fed at

the other end of the shaft, compute the efficiency of the crusher.

Answer 1

The efficiency of the crusher $=1- \frac{Density \space of \space calcite}{Specific \space surface \space ratio \space for \space the \space feed}$

The efficiency of the crusher $= 1- \frac{2.65}{3.5}= 0.25714 \implies 25.714 \%$