Mechanical Operations

Sphericity of pulverised coal is__________________? A. 1B. < 1 C. > 1 D. ∞

The reduction ratio for grinders is defined as (where, Df and Dp are average diameters of feed and product respectively) ? A. Df/Dp B. Dp/Df C. Df – Dp D. None of these

Maximum size reduction in a ball mill is done by the, ______________ action? A. Attrition B. CompressionC. Impact D. Cutting

Which of the following is a fine crusher ? A. Blake jaw crusher B. Gyratory crusherC. Toothed roll crusher D. Dodge jaw crusher

_______________ mixer is used for devulcanisation of rubber scrap & making water dispersion & rubber solution? A. TumblerB. Banbury C. Muller D. Ribbon blender

For spheres, the surface shape factor is given by (where, A = area, V = volume, and D = diameter) ? A. π = (A/D2) B. π/6 = (V/D3) C. AD/V D. None of these

Gravity stamp mill is meant for the ___________________ crushing? A. Primary B. IntermediateC. Fine D. Ultrafine

Reciprocating screens are normally inclined at an angle of 5° with the horizontal and employ gyratory motion at feed end & reciprocating motion at the discharge end. They are not suitable for the screening of the ___________________? A. Light metal powder down upto 4 mesh size B. Dry chemicalsC. Heavy tonnages of rocks or gravel…

A fluid energy mill is used for __________________? A. Cutting B. GrindingC. Ultra-grinding D. Crushing

In a size reduction crushing operation, the feed size is 10 to 50 mm, while the product size is 2 to 10 mm. This is a case of _______________ crushing? A. Primary B. SecondaryC. Fine D. Ultrafine