0% 0 Mechanical Operations Quiz 2 1 / 50 Capacity (in tons/hr) of jaw/gyratory crusher is equal to (where, L = length of the receiving opening, cm S = greater width of the discharge opening, cm) ? L.S 0.087 L.S L.S/0.087 0.01 L.S 2 / 50 Bond crushing law__________? Is less realistic in estimating the power requirements of commercial crushers States that the work required for the crushing is proportional to the new surface created Calls for relatively less energy for the smaller product particles, than does the Rittinger law States that the work required to form particle of any size from very large feed is proportional to the square root of the volume to surface ratio of the product 3 / 50 Cartridge filters are termed as ?edge? filters, because of the fact that the__________? Solids are not deposited at the edge of the disk Disks have very sharp edge Bulk of the solids are removed at the periphery of the disks None of these 4 / 50 During the washing of cake__________? All the resistances are constant Filter medium resistance increases Filter medium resistance decreases Cake resistance decreases 5 / 50 As per Taggart?s formula, the capacity (kg/hr) of Jaw & Gyratory crushers (for gapes of 10 to 60 cms) is equal to (where, L = Length of feed opening, cms S = Maximum width of discharge opening, cms) ? LS ?(LS) 250 LS 93 LS 6 / 50 Energy consumption in a crusher decreases with increase in the__________? Size of feed (at constant reduction ratio) Size of the product (at constant feed size) Capacity of the crushing machine All A., B. & C. 7 / 50 Colloidal mills are used for _______ grinding? Fine Intermediate Coarse Ultrafine 8 / 50 Cumulative analysis for determining surface is more precise than differential analysis, because of the________? Assumption that all particles in a single fraction are equal in size, is not needed Assumption that all particles in a single fraction are equal in size None of these Fact that screening is more effective 9 / 50 Diatomaceous earth is a/an__________? Filter aid Catalyst Explosive Filter medium 10 / 50 During size reduction by a jaw crusher, the energy consumed decreases with the___________? None of these Increasing size of feed at constant reduction ratio Decreasing size of product at constant size of feed Decreasing machine capacity 11 / 50 Balls for ball mills are never made of__________? Cast iron Alloy steel Lead Forged/cast steel 12 / 50 During washing of filter at the end of constant pressure filtration, the rate of washing equals the rate of filtration_____? At the end of filtration At the end of filtration, but decreases with time subsequently At time zero When half the filtrate has been obtained 13 / 50 Chance process is used for the_________? Concentration of pyrites Water treatment Concentration of iron ore Cleaning of coal 14 / 50 Dust laden air can be purified using a______? Cyclone separator Bag filter Gravity settler Tubular centrifuge 15 / 50 During filtration operation, the filtrate encounters the resistance of the _____? All A., B. and C. Channel carrying the slurry to the upstream side of the cake and filtrate away from the filter medium Filter medium Cake 16 / 50 Coal is finally pulverised to 200 mesh size for burning in boilers by a_____? Gyratory crusher Ball mill Roll crusher Hammer crusher 17 / 50 Ball mills and tube mills with flint or porcelain balls are used for size reduction of________? Limestone Rubber Asbestos Non-metallic ores 18 / 50 At low Reynold?s number, the power (P) required for agitating a fluid in a stirred tank becomes independent of inertial forces. In this limit, indicate which of the following relations is satisfied: Po = ?/?N3 D5: Power number Re = ? N D2/?: Reynold?s number N is the impeller rotational speed, and D is the impeller diameter ? Po ? Re0.0 Po ? Re-1.0 Po ? Re1.0 Po ? Re0.5 19 / 50 Dispersion of a gas through liquid is done by using a___________? Kneader None of these Sparger Masticator 20 / 50 All resistances during washing of cake _______? Remain constant Increases None of these Decreases 21 / 50 Cyclones are used primarily for separating__________? Solids from fluids Solids Solids from solids Liquids 22 / 50 Capacity of flight conveyor in tons/hr is given by (where, W & D = width and depth of flight respectively in metre V = speed of the conveyor, metre/second ? = bulk density of material, kg/m3) ? 3.6 W.V.? 3.6 W.D.V 3.6 W.D.V.? 3.6 D.V.? 23 / 50 Cake resistance is_____? None of these Important in the beginning of filtration Decreased with the time of filtration Independent of pressure drop 24 / 50 Close circuit grinding by a ball mill with air sweeping employs a _________? Neither A. nor B. Cyclone separator between mill & classifier Both A. & B. Classifier 25 / 50 Apron conveyors are used for _____ ? Heavy loads & long runs None of these Heavy loads & short runs Small loads & long runs 26 / 50 Ball mill is used for___________? Attrition Coarse grinding Crushing Fine grinding 27 / 50 Basic slag is not ground in__________? Compartment mills Ball mills Tube mills Jaw crushers 28 / 50 Crushing efficiency of a machine ranges between ___________ percent? 5 to 10 50 to 70 20 to 25 0.1 to 2 29 / 50 Arrange the following size reduction equipment in the decreasing order of the average particle size produced by each of them ? Fluid energy mill, Ball mill, Jaw crusher Fluid energy mill, Jaw crusher, Ball mill Jaw crusher, Ball mill, Fluid energy mill Ball mill, Jaw crusher, Fluid energy mill 30 / 50 Choke crushing (in case of a Jaw crusher) compared to free crushing___________? Consumes less power Consumes more power Results in increased capacity Both A. and C. 31 / 50 Energy consumed for crushing one ton of material ranges from _______ kWh? 0.01 to 0.1 4 to 5 2 to 3.5 0.5 to 1.5 32 / 50 Critical Speed (Nc) of a ball mill is given by (where R1 and R2 are radii of ball mill and the ball respectively) ? Nc = (1/2?). ?(R1 ? R2/g) Nc = (1/?). ?(g/R1 ? R2) Nc = (1/2?). ?(g/R1 ? R2) Nc = (1/4?). ?(g/R1 ? R2) 33 / 50 Compressibility co-efficient for an absolutely compressible cake is________? 1 0 to 1 ? 0 34 / 50 Cement clinker is reduced to fine size by a _______? Ball mill Tube mill Roll crusher Hammer mill 35 / 50 As the product becomes finer, the energy required for grinding_____? Is same as for coarser grinding Is 1.5 times that for coarser grinding Increases Decreases 36 / 50 Feed size of ? 25 cms can be accepted by _________? Ball mill Rod mill Jaw crusher Fluid energy mill 37 / 50 During agitation of liquids, the__________? Froude number is independent for the curves between power number and Reynolds number in baffled system All A., B. and C. Froude number is used to account for the effect of surface (e.g., the centre vortex) on the power number Power number becomes independent of impellers Reynolds number at high Reynolds number, but is dependent on the geometry of the impeller 38 / 50 Angle of nip of the crushing rolls does not depend upon the________? Product size Speed of the rolls Diameter of the rolls Feed size 39 / 50 During agitation of liquids, power consumption during laminar flow is not proportional to the _________? Cube of impeller diameters Square of rotational speed Density of the liquid Viscosity of the liquid 40 / 50 Energy requirement (per unit mass of material crushed/ground) is highest for___________? Ball mill Fluid energy mill Rod mill Jaw crusher 41 / 50 Crushing of mineral particles is accomplished in a ?cage mill?, when one or more alloy steel bars are revolved in opposite directions. It is a type of _______ mill? Roll Impact Vibratory None of these 42 / 50 Dust collection efficiency of electrostatic precipitator can be as high as 99.9%. Maximum temperature and pressure of dust laden gas that can be cleaned in an electrostatic precipitator is respectively ? 200?C and 5 atm 1000?C and 10 atm 500?C and 50 atm 1000?C and 500 atm 43 / 50 Critical speed of rotation, N (in rps ? rotation per second) of a trammel is equal to (where, g = acceleration due to gravity = 9.81 m/sec2 and, r = radius of trammel, metre.) ? 2?. ?(g/r) ? ?(g/r) (1/?). ?(g/r) (1/2?). ?(g/r) 44 / 50 Carbon black is pulverised in a________? Gyratory crusher Hammer crusher Ball mill Roll crusher 45 / 50 Crushing efficiency is the ratio of the ________ ? Energy absorbed by the solid to the surface energy created by crushing Energy absorbed by the solid to that fed to the machine Energy fed to the machine to the surface energy created by crushing Surface energy created by crushing to the energy absorbed by the solid 46 / 50 Dry powdery solid materials are transported by a _______ conveyor? Bucket None of these Belt Screw 47 / 50 As particle size is reduced___________? Screening becomes progressively more difficult None of these Screening becomes progressively easier Capacity and effectiveness of the screen is increased 48 / 50 Equivalent diameter of a particle is the diameter of the sphere having the same ___________? None of these Ratio of surface to volume as the actual volume Ratio of volume to surface as the particle Volume as the particle 49 / 50 Colloid mills achieve size reduction mainly by_____? Cutting Attrition Compression Impact 50 / 50 Bucket elevators are not suitable for the vertical lifting of __________ materials? Fine (e.g. ? 200 mesh size coal) Sticky (e.g. clay paste) Free flowing Small lumpy (e.g. grains and sand) Provide Your Information Your score is The average score is 0% LinkedIn Facebook Twitter 0% Restart quiz Send feedback Share on facebook Facebook Share on twitter Twitter Share on whatsapp WhatsApp PrevMechanical Operations Quiz 1 Mechanical Operations Quiz 3Next
