Mechanical Operations Questions

• For compounding solid rubber and plastic materials (filler incorporation and intensive mixing), which mixer is the most suitable choice in an industrial processing line?
• In a ball mill used for comminution, which mechanism is primarily responsible for achieving the maximum size reduction of particles?
• In mechanical conveying classifications, which of the following is typically not listed under the division “carriers” (consider standard plant handling taxonomy)?
• Trommel screens separate a mixed particulate feed primarily on the basis of which material property?
• In screening operations, how does increasing the feed capacity (throughput per unit area) generally affect the overall screen effectiveness (sharpness of separation and undersize recovery)?
• When the density difference between two liquid phases is very small (e.g., milk and cream), which separator design is most suitable for achieving effective phase separation?
• For primary crushing of very hard, lumpy materials in mineral processing, which crusher is most appropriate to handle the duty at high capacity and large feed sizes?
• In mineral separation terminology, the “selectivity index” is defined as which of the following (consider two-mineral separation with relative rejections and recoveries)?
• Regarding hammer crushers (impact crushers with swinging hammers), which statement is correct about rotor orientation and design variants used in industry?
• For a cubical particle, if the “equivalent diameter” is taken equal to the cube height (edge length), what is the sphericity value (use the standard ratio of surface area of volume-equivalent sphere to actual surface area when equivalent diameter equals edge)?
• In paper manufacturing, filtration of large volumes of process water is commonly carried out using which type of filter arrangement?
• Compared to a conventional ball mill, a tube mill is characterised by which dimensional ratio and typical grinding behaviour?
• Screen capacity (throughput) depends on many variables. Which of the following is generally not considered an intrinsic design/operation function for capacity estimation?
• For transporting sticky bulk materials reliably over short to moderate distances, which conveyor type is generally the most suitable choice?
• In a rotary drum vacuum filter operating at steady conditions, which resistance term most often controls the overall filtration rate once cake formation has begun?
• For mixing very high viscosity liquids (greater than 50,000 cP), which agitator design—characterised by a large blade area and slow rotational speed—is preferred?
• In modern power plants, coal is finally pulverised to about 200 mesh for boiler firing using which comminution device?
• For a perfect sphere, which formula gives the volume shape factor in terms of diameter D and volume V (identify the standard expression)?
• In cement and slag grinding practice, basic slag is generally not ground in which of the following mill types (consider typical plant selections and lining compatibility)?
• In particle size reduction equipment design for mineral processing and cement industries, what is the typical relationship between the shell length and the shell diameter (L/D ratio) of a standard ball mill? Provide the most general statement rather than a specific numeric value.