Mechanical Operations Questions

• In a closed-circuit, air-swept ball mill system, which combination is normally used to return coarse material and collect fine product?
• Which filter type is best suited for gelatinous solids that tend to plug the septum, by first depositing a protective pre-deposited layer on the medium?
• Sorting (hydraulic) classifiers that use differential settling separate particles primarily based on differences in which property?
• What is the primary size-reduction mechanism in toothed roll crushers when handling friable or soft rock and coal?
• Which oxide is generally not associated with hematite (Fe2O3) iron ore as a natural constituent or common gangue impurity?
• In jaw crushers, how does choke crushing (operating with a full chamber) compare to free crushing in terms of capacity and power consumption?
• In gas cleanup for coke-oven gas, which device is most suitable for removing trace liquid tar fog (submicron to micron droplets)?
• During constant-pressure filtration of a slurry, how does the filtration rate vary with time as the cake builds on the medium?
• The angle of nip in crushing rolls primarily depends on particle friction and geometry. Which factor below does it not significantly depend upon?
• Compared with a plate-and-frame filter press, a shell-and-leaf (pressure leaf) filter typically offers which combination of advantages in operation?
• Bond work index correlation: the work index measured in wet grinding is often adjusted to estimate dry-grinding energy. What factor is used to convert wet-grinding work index to an equivalent dry-grinding value?
• Ribbon blenders (U-trough with helical ribbons) are most suitable for homogeneous mixing of which type of materials?
• For a rotating trommel, how does the critical speed N vary with drum diameter D? Choose the correct proportionality.
• What is the standard process term for removing fine suspended solids from liquids under gravity in a clarifier or settling tank?
• According to Rittinger’s law for crushing and grinding, the energy required is directly proportional to which quantity?
• In froth flotation, which reagent acts as an activator that enhances the floatability of specific minerals (e.g., activating sphalerite for subsequent collector action)?
• For the same feed size range, which crusher generally gives the least reduction ratio (i.e., produces the least overall size reduction per stage)?
• According to Taggart’s empirical relation for jaw and gyratory crushers (gape 10–60 cm), the capacity in kg/hr is proportional to which expression in terms of L (feed opening length, cm) and S (maximum discharge opening width, cm)?
• Which comminution energy law is most appropriate for fine grinding where surface area increase dominates the energy requirement?
• Comminution principle: for the coarse reduction of hard, strong solids (e.g., run-of-mine ore or clinker), which primary breakage mechanism is preferred for efficient size reduction and control of product shape?