Description : Rittinger's crushing law states that (A) Work required to form a particle of any size is proportional to the square of the surface to volume ratio of the product (B) Work required to form a ... ) For a given machine and feed, crushing efficiency is dependent on the size of the feed & product
Last Answer : (C) Work required in crushing is proportional to the new surface created
Description : For crushing of solids, the Rittinger's law states that the work required for crushing is proportional to (A) The new surface created (B) The size reduction ratio (C) The change in volume due to crushing (D) None of these
Last Answer : (A) The new surface created
Description : . Which of the following equations is Rittinger's crushing law? (Where P = power required by the machine, m = feed rate, k = a constant, Ds̅a & D̅sb = volume surface mean diameter of feed & product respectively.) (A) P/m = K/ ... K . ln D̅sa /D̅sb (C) P/m = K . (1/ D̅sb - 1/Ds̅a ) (D) None of these
Last Answer : (C) P/m = K . (1/ D̅sb - 1/Ds̅a )
Description : The constants (Kb, Kr and Kk) used in the laws of crushing (i.e., Bond's law, Rittinger's law and Kick's law) depend upon the (A) Feed material (B) Type of crushing machine (C) Both (A) & (B) (D) Neither (A) nor (B)
Last Answer : (C) Both (A) & (B)
Description : Which of the following crushing laws is most accurately applicable to the fine grinding of materials? (A) Bond's crushing law (B) Kick's law (C) Rittinger's law (D) None of these
Last Answer : (C) Rittinger's law
Description : Which of the following gives the work required for size reduction of coal to -200 mesh in a ball mill most accurately? (A) Rittinger's law (B) Kick's law (C) Bond's law (D) None of these
Last Answer : (A) Rittinger's law
Description : According to Taggart's rule for selecting between a gyratory crusher and a jaw crusher; the later should be used, if the hourly tonnage to be crushed divided by the square of the gape expressed in cm is less than (A) 0.00184 (B) 0.0184 (C) 0.184 (D) 1.84
Last Answer : (B) 0.0184
Description : Bond crushing law (A) Calls for relatively less energy for the smaller product particles, than does the Rittinger law (B) Is less realistic in estimating the power requirements of commercial crushers ( ... (D) States that the work required for the crushing is proportional to the new surface created
Last Answer : (A) Calls for relatively less energy for the smaller product particles, than does the Rittinger law
Description : Fick's law relates to (A) Energy consumption (B) Final particle size (C) Feed size (D) None of these
Last Answer : (A) Energy consumption
Description : Rittinger's number designates the new surface created per unit mechanical energy absorbed by the material being crushed. Larger value of Rittinger's number of a material indicates its (A) Easier grindability (B) Poor grindability (C) High power consumption in grinding (D) None of these
Last Answer : (A) Easier grindability
Description : According to Bond crushing law, the work required to form particle of size 'D' from very large feed is (where (S/V)p and (S/V) f are surface to volume ratio of the product and feed respectively). (A) (S/V)p (B) √(S/V)p (C) (S/V) 2 p (D) (S/V) f
Last Answer : (B) √(S/V)
Description : __________ is concerned with the adsorption equilibria. (A) Fick's law (B) Gibb's equation (C) Freundlich equation (D) None of these
Last Answer : (C) Freundlich equation
Description : The equation, NA = (DAB . Pt /RTZ . PBM) (PA1 - PA2 ) is for (A) Fick's second law of diffusion (B) Steady state diffusion for stagnant case (C) Liquid M.T.C. by Higbie penetration theory (D) None of these
Last Answer : (B) Steady state diffusion for stagnant case
Description : Convective heat transfer, in which heat is transferred by movement of warmed matter is described by (A) Fourier's law (B) Newton's law of cooling (C) Fick's law (D) None of these
Last Answer : (B) Newton's law of cooling
Description : Pick out the wrong statement pertaining to the roll crushers. (A) Maximum feed size determines the required roll diameter (B) For hard material's crushing, the reduction ratio should not ... ratio and differential roll speed affect production rate & energy consumed per unit of surface produced
Last Answer : (C) Both the rolls run necessarily at the same speed
Description : Pick out the correct statement. (A) Plastic chips are called non-cohesive solids (B) Kick's crushing law is, P/m = K . ln (D̅sa /Ds̅b ) (C) Communition is a generic term for size enlargement ... per ton of product, such that 80% of it passes through a 200 mesh screen, is called 'Work index'
Last Answer : (B) Kick's crushing law is, P/m = K . ln (D̅sa /Ds̅b )
Description : 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). (A) LS (B) 93 LS (C) 250 LS (D) √(LS)
Last Answer : (B) 93 LS
Description : Rittinger number which designates the new surface produced per unit of mechanical energy absorbed by the material being crushed, depends on the (A) State or manner of application of the crushing force (B) Ultimate strength of the material (C) Elastic constant of the material (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Pick out the material having minimum Rittinger's number. (A) Calcite (B) Pyrite (C) Quartz (D) Galena
Last Answer : (C) Quartz
Description : Crushing efficiency is the ratio of the (A) Surface energy created by crushing to the energy absorbed by the solid (B) Energy absorbed by the solid to that fed to the machine (C) Energy ... surface energy created by crushing (D) Energy absorbed by the solid to the surface energy created by crushing
Last Answer : (A) Surface energy created by crushing to the energy absorbed by the solid
Description : The work index in Bond's law for crushing of solids has the following dimensions (A) No units (dimensionless) (B) kWh/ton (C) kW/ton (D) kWh.m1/2 /ton
Last Answer : (B) kWh/ton
Description : General crushing equation is given by d(P/m) = -K (dD̅S /D̅ n S ). Bond's crushing law is obtained by solving this equation for n = __________ and feed of infinite size. (A) 1 (B) 1.5 (C) 2 (D) 2.5
Last Answer : (B) 1.5
Description : Pick out the wrong statement. (A) Gape is the greatest distance between the crushing surfaces or the jaws (B) The angle of nip (2α) is the angle between roll faces at the level where they will ... Reduction ratio is the ratio of the maximum size of the particles in the feed to that in the product
Last Answer : (C) Crushing efficiency is the ratio of the energy absorbed by the solid to the surfaces energy created by crushing
Description : Energy consumption in a crusher decreases with increase in the (A) Size of the product (at constant feed size) (B) Capacity of the crushing machine (C) Size of feed (at constant reduction ratio) (D) All (A), (B) & (C)
Last Answer : (D) All (A), (B) & (C)
Description : A fluid energy mill is used for (A) Cutting (B) Grinding (C) Ultra-grinding (D) Crushing
Last Answer : (C) Ultra-grinding
Description : A fluid energy mill is used for (A) Cutting (B) Grinding (C) Ultra grinding (D) Crushing
Last Answer : (C) Ultra grinding
Description : Energy consumed for crushing one ton of material ranges from __________ kWh. (A) 0.01 to 0.1 (B) 0.5 to 1.5 (C) 2 to 3.5 (D) 4 to 5
Last Answer : (B) 0.5 to 1.5
Description : When kinetic energy of the crash is used up crushing the metal of the vehicle?
Last Answer : 1
Description : What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls? (A) 16° (B) 32° (C) 40° (D) 46°
Last Answer : (B) 32°
Description : Pick out the wrong statement. (A) Recycled coarse material to the grinder by a classifier is termed as circulating load (B) Wear and tear in wet crushing is more than that in dry crushing of ... a pipeline which permits the solids to settle down due to reduction in velocity of the dust laden gas
Last Answer : (C) Size enlargement (opposite of size reduction) is not a mechanical operation
Description : 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. (A) Impact (B) Roll (C) Vibratory (D) None of these
Last Answer : (A) Impact
Description : Half the angle of nip, (α), for a roll crusher is given by (where, dr, dp and df are diameters of crushing rolls, feed particles and rolls gap respectively). (A) cos α = (dr + dp)/(dr + df) (B) cos α = (dr + df)/(dr + dp) (C) tan α = (dr + dp)/(dr + df) (D) sin α = (dr + dp)/(dr + df)
Last Answer : (A) cos α = (dr + dp)/(dr + df)
Description : Size reduction of the __________ can be suitably done by ball mills, crushing rolls and rod mills. (A) Metalliferous ores (B) Non-metallic ores (C) Basic slags (D) Asbestos & mica
Last Answer : (A) Metalliferous ores
Description : For grinding of cereals, grains, spices, pigments, saw dust, cork etc., the most extensively used size reduction equipment is a (A) Buhrstone mill (B) Ball mill (C) Crushing rolls (D) Hammer mill
Last Answer : (A) Buhrstone mill
Description : In case of a hammer crusher, (A) Crushing takes place by impact breaking (B) Maximum acceptable feed size is 30 cms (C) Reduction ratio can be varied by adjusting the distance from cage to hammers (D) All (A), (B) and (C)
Description : Size reduction of asbestos and mica is done by (A) Hammer mills (B) Rod mills (C) Gyratory crushers (D) Crushing rolls
Last Answer : (A) Hammer mills
Description : Crushing efficiency of a machine ranges between __________ percent. (A) 0.1 to 2 (B) 5 to 10 (C) 20 to 25
Last Answer : (A) 0.1 to 2
Description : Choke crushing (in case of a Jaw crusher) compared to free crushing (A) Results in increased capacity (B) Consumes less power (C) Consumes more power (D) Both (A) and (C)
Last Answer : (C) Consumes more power
Description : Ball mill is used for (A) Crushing (B) Coarse grinding (C) Fine grinding (D) Attrition
Last Answer : (C) Fine grinding
Description : Stamp mills are generally used for crushing (A) Iron ores (B) Gold ores (C) Talc (D) Diamond
Last Answer : (B) Gold ores
Description : Which of the following is used for primary crushing of very hard lumpy materials? (A) Toothed roll crusher (B) Gyratory crusher
Last Answer : (B) Gyratory crusher
Description : Gravity stamp mill is meant for the __________ crushing. (A) Primary (B) Intermediate (C) Fine (D) Ultrafine
Last Answer : (C) Fine
Description : 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) Secondary (C) Fine
Description : Theoretical capacity of crushing rolls in tons/hr is given by (where, V = peripheral velocity, m/sec. W = width of rolls, m Dr = distance between rolls ρ = density of material to be crushed, kg/m3 here, V =πND where, N = speed of the rolls ... V.W.Dr.ρ (B) 3.6 V.W. ρ (C) 3.6 W.Dr.ρ (D) 3.6 V.W.Dr/ρ
Last Answer : (A) 3.6 V.W.Dr.ρ
Description : In a size reduction crushing operation, feed size is 100 to 300 mm. while the product size is 10 to 50 mm. This is a case of the __________ crushing. (A) Primary (B) Secondary (C) Fine (D) Ultrafine
Last Answer : (B) Secondary
Description : In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the __________ crushing. (A) Secondary (B) Fine (C) Primary (D) Ultrafine
Last Answer : (C) Primary
Description : Pick out the wrong statement. (A) For the compressible cake, voidage & the specific resistance of the cake can be assumed to be constant (B) Cake resistance is independent of the pressure ... Crushing of explosive materials are done by employing dry-grinding (D) Gyratory crusher is a coarse crusher
Last Answer : (B) Cake resistance is independent of the pressure drop
Description : Pick out the wrong statement: (A) Magnetic separation method can be employed to treat both dry & wet ores (B) Reduction ratio in crushing operation is defined as the ratio of minimum feed ... ) Gyratory crusher is used for coarse crushing (D) Screens are of stationary, moving and vibratory types
Last Answer : (B) Reduction ratio in crushing operation is defined as the ratio of minimum feed size to the maximum product size
Description : Angle of nip of the crushing rolls does not depend upon the (A) Diameter of the rolls (B) Speed of the rolls (C) Product size (D) Feed size
Last Answer : (B) Speed of the rolls
Description : Austenitic manganese steel used for making jaws of crushing machines contains about __________ percent manganese. (A) 1.5-2 (B) 3.5-4.5 (C) 7-9 (D) 12-14
Last Answer : (D) 12-14