0% 1 Mechanical Operations Quiz 1 1 / 50 A pebble mill__________? Both B. and C. Is a tube mill lined with ceramic or other non-metallic liner Employs flints or ceramic pebbles as the grinding medium Is a ball mill 2 / 50 ________ is defined as the geometric mean of the relative rejections and the relative recoveries of two minerals? None of these Concentration ratio Separation efficiency Selectivity index 3 / 50 _______ are used for the separation of coarse particles from a slurry of fine particles? Decanters Classifiers Thickeners Hydrocyclones 4 / 50 A belt conveyor used for the transportation of materials can_____? Travel at a speed upto 300 metres/minute All A., B. and C. Handle materials upto 5000 tons/hr Run upto 1 km 5 / 50 A ________ employs a set of screen across a flow channel for the separation of dirt/rust from a flowing liquid stream? Strainer Classifier Thickener Clarifier 6 / 50 A fluid energy mill is used for__________? Ultra grinding Cutting Crushing Grinding 7 / 50 Addition of filter aid to the slurry before filtration is done to ________ of the cake? Decrease the compressibility co-efficient Increase the compressibility co-efficient Decrease the porosity Increase the porosity 8 / 50 A propeller agitator________? All A., B. and C. Is used for mixing high viscosity pastes Produces mainly axial flow Runs at very slow speed (2 rpm) 9 / 50 A suspension of glass beads in ethylene glycol has a hindered settling velocity of 1.7 mm/s, while the terminal settling velocity of a single glass bead in ethylene glycol is 17 mm/s. If the Richardson-Zaki hindered settling index is 4.5, the volume fraction of solids in the suspension is______? 0.4 0.6 None of these 0.1 10 / 50 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________? 0.00184 0.0184 1.84 0.184 11 / 50 _______ mean diameter of particles is given by ? (xi/Dpi ?)? Arithmetic Volume surface Mass Volume 12 / 50 A ______ mixer resembles a ball mill without balls? Tumbling Banbury Pan Pug mill 13 / 50 A tube mill as compared to a ball mill___________? Has larger length/diameter ratio (>2 as compared to 1 for ball mill) Employs smaller balls Gives finer size reduction but consumes more power All A., B. and C. 14 / 50 A widely used size reduction equipment for _______ is Bradford breaker? Wheat Talc Iron core Coal 15 / 50 Additives used for promoting the flocculation of particles is a/an _______? Surface active agent Neither A. nor B. Electrolyte Both A. & B. 16 / 50 ________ balls capable of grinding the feed in a ball mill gives the maximum efficiency ? Cast iron Minimum size Maximum size Elliptical 17 / 50 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) ? ?(S/V)p (S/V)p (S/V)2p (S/V)f 18 / 50 A screen is said to be blinded, when the_____? Over-sizes are present in undersize fraction Under-sizes are retained in oversize fraction Screen capacity is abruptly increased Screen is plugged with solid particles 19 / 50 A compressible cake has the__________? Maximum porosity at the upstream side None of these Maximum porosity at the filter medium Same porosity throughout the cake thickness 20 / 50 A fluid energy mill is used for ___________? Grinding Crushing Ultra-grinding Cutting 21 / 50 ________ mill is normally used for grinding of talc? Tube Ring-roll Pebble Compartment 22 / 50 ________ centrifuge is the most suitable for separation of non-friable crystals? Suspended batch basket Perforated horizontal basket continuous Disc-bowl Tubular bowl 23 / 50 A straight line is obtained on plotting reciprocal of filtration rate vs. the volume of filtrate for ________ flow of filtrate? Incompressible cake and turbulent Compressible cakes and laminar Compressible cake and turbulent Incompressible cake and laminar 24 / 50 __________ conveyor is the most suitable for short distance transportation of non-abrasive loose materials like garbage, grain, food wastes etc? Drag Screw Belt Flight 25 / 50 ______ mills are termed as impactors? None of these Rolling-compression Cage Hammer 26 / 50 ________ mill is not used for grinding wheat into flour and for milling of cereals & other ? vegetable products. Buhrstone Attrition Roller Pebble 27 / 50 ______ conveyors are also called scrapers? Screw Both B. & C. Apron Helical flight 28 / 50 ______ are mixed using ribbon blenders ? High viscosity liquids Thick pastes Dry powders Lumpy solids and low viscosity liquids 29 / 50 A tube mill compared to a ball mill___________? Has a higher length/diameter ratio Produces a coarser product Uses much larger balls Has a higher diameter/length ratio 30 / 50 Actual operating speed of a ball mill may vary from 65 to 80% of the critical speed. Which of the following duties would require the ball mill to be operated at maximum percentage of critical speed ? Wet grinding in high viscous suspension Dry grinding of large particles in un-baffed mills Wet grinding in low viscous suspension Dry grinding of large particles (upto 1.25 cms) 31 / 50 A sand mixture was screened through a standard 10-mesh screen. The mass fraction of the oversize material in feed, overflow and underflow were found to be 0.38, 0.79 and 0.22 respectively. The screen effectiveness based on the oversize is__________? 0.58 0.62 0.5 0.68 32 / 50 ______ is the most suitable for compounding rubber and plastic solids ? Charge can mixer Banbury mixer Pan mixer Pug mill 33 / 50 A ______ mill is a revolving mill divided into two or more sections by perforated partitions in which preliminary grinding takes place at one end and the finishing grinding at the discharge end? Tube Pebble Rod Compartment 34 / 50 A cottrell precipitator makes use of the _______ for dusty air cleaning? Electric spark Corona discharge Alternating current None of these 35 / 50 200 mesh screen means 200 openings per_______? inch2 cm cm2 inch 36 / 50 ________ mixer is used for devulcanisation of rubber scrap & making water dispersion & rubber solution? Muller Ribbon blender Tumbler Banbury 37 / 50 Activators are those chemicals which help buoying up one mineral in preference to the other in the froth floatation process. Which of the following is an activator ? Sodium carbonate Cresylic acid Copper sulphate Calcium carbonate 38 / 50 _____ conveyor is the most suitable for long distance transportation of cold, nonabrasive granular/irregular shape/fine materials? Bucket Belt Apron Screw 39 / 50 _______ is used for producing a thick suspension from a thin slurry? Plate and frame filter press Cartridge filter Rotary drum vacuum filter Pressure filter thickener 40 / 50 Agglomeration of individual particles into clusters (flocs) is called flocculation. To prevent flocculation, the most commonly used dispersing agents are_________? Carbonates Sulphates Bi-carbonates Silicates & phosphates 41 / 50 ______ mills are termed as disintegrators? Pebble Cage Compartment All tumbling 42 / 50 A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ?L) located at a radial distance R from the axis of rotation. The thickness of the liquid film is ? and no cake is formed. The initial pressure drop during filtration is _____? ?w2 . ?2 . ?L ?w2 . R2 . ?L ?w2 . ??L (2R + ?) ?w2 . R . ?L(R + 2?) 43 / 50 ______ Centrifuge is normally used in sugar mills? Suspended batch basket Tubular bowl Disc-bowl Perforated horizontal basket continuous 44 / 50 _____ mills fall in the category of tumbling mills ? All A., B. & C. Ball and pebble Rod and tube Compartment 45 / 50 ________ is a cohesive solid ? Wet clay None of these Wheat Sand 46 / 50 A 30% (by volume) suspension of spherical sand particles in a viscous oil has a hindered settling velocity of 4.44 ?m/s. If the Richardson Zaki hindered settling index is 4.5, then the terminal velocity of a sand grain is__________? 22.1 ?m/s 0.90 ?m/s 0.02 ?m/s 1 ?m/s 47 / 50 200 mesh sieve size corresponds to ______ microns? 74 24 200 154 48 / 50 A filter press is_____? Having prohibitively high maintenance cost Not suitable for wide range of materials under varying operating conditions of cake thickness and pressure A batch filter Not suitable, if the liquid is the main product 49 / 50 _______ baffles are provided in ball mills ? No Horizontal None of these Only two 50 / 50 _______ mill is not a revolving mill ? Cage Tube Compartment Pebble 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 PrevMaterials and Construction Quiz 10 Mechanical Operations Quiz 2Next
