Code No.: NR-221804 II B.Tech II Semester Suppl. Examinations, April/May 2004 MINERAL DRESSING (Metallurgy and Material Technology) Time: 3 hours Max. Marks: 80 Answer any FIVE questions All questions carry equal marks --1.a) What are the objectives and advantages of mineral dressing? b) State and explain the laws of size reduction comment on their applicability.
Explain the working of a role crusher with a neat sketch. Derive the relation between roll diameter, feed size, product size and angle of nip of the coefficient of friction between mineral and steel is 0.3. Calculate the minimum diameter of rolls required for a roll crusher working with a feed of 40 mm size to get a product of 8mm size.
3.
Discuss the theory of grinding in a ball mill. Derive the relation for critical speed of ball mill in terms of diameters of ball mill and grinding steel ball.
4.a) b)
Write a brief note on sizing scales and industrial sizing methods. What is meant by ‘equal settling’ particles? Explain the terms ‘free’ and hindered settling ratios. What is their importance in mineral dressing? Assuming Stokes law calculate the settling ratios of galena to quartz i) In Water and ii) In a suspension of 35% quartz in water Specific gravity data: Galena: 7.5 Quartz: 2.65 Water : 1
5.a)
Explain the terms: ‘selectivity index and economic recovery. In a concentration operation, 0.2 tons of concentrate worth 1000 rupees per ton is obtained from an are while theoritically 0.15 tons of concentrate worth 1500 rupees is expected. Calculate the economic recovery. With a neat sketch explain the operating principles of tabling. Explain, with suitable illustrations the physical and chemical aspects of flotation.
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7.a)
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With a neat sketch explain the chance process of coal cleaning. Draw typical wash ability curves and explain their use. Giving a typical flow sheet explain the important steps in concentration of lead – zine one by selective blotation.
8. a) b) c) d)
Write short notes on: Tool a roll crusher. Electrostatic separation Sorting classifiers Mineral Jig. $$$
Set No
2
b)
Define degree of liberation How is it determined? Mention the percentage liberation achieved in case of sulphide minerals after concentration and coal after washing. Explain the working of gyratory crusher with a neat sketch what are its advantages over jaw crusher? Calculate the capacity of a gyratory crusher with conical average diameter of 80 cm and width of discharge opening 10cm.
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Code No.: NR-221804 II B.Tech II Semester Suppl. Examinations, April/May 2004 MINERAL DRESSING (Metallurgy and Material Technology) Time: 3 hours Max. Marks: 80 Answer any FIVE questions All questions carry equal marks --1. Distinguish between ’mineral’ and ‘ore’ Discuss the exploitable characteristics of minerals used for dressing and name the techniques adopts in each case giving examples of typical minerals in each case.
Compare open circuit versus closed circuit grinding. What are Davis zones? Explain with a neat sketch.
4.a)
Why sizing is necessary? Compare and contrast laboratory and industrial sizing methods. State stokes and Newton’s laws and indicate their scope of application in mineral dressing operations. Assuming Newton’s law calculate the setting ratios of galena to quartz i) In Water ii) In a suspension of 40% quartz in water Specific gravity date: Galen : 7.5 Quartz : 2.65 Water : 1
b)
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3.a) b)
Stating the principle involved discuss any method of gravity concentration. Briefly explain the uses of magnetic separation in mineral dressing, giving suitable examples.
6.a) b)
What is a classifier? Explain with a neat sketch the working of a hydra cyclone. What is Jigging? With a neat sketch explain the working of a mineral jig.
7.a)
Give a typical flow – sheet of the flotation circuit of a plant for concentrating chalcopyrite one, containing pyrite and gauge. Justify the use of various reagents added in the flow sheet explaining clearly their roles.
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8. a) c)
Write short notes on: Wilbley table Electrostatic separation.
b) d) $$$
Ratio of concentration and recovery Chance process.
Set No
3
3.a) b) 4.a) b)
5.a)
b)
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Indicate how the capacity of Jaw crusher is calculated. Explain the working of dodge type jaw crusher with a neat sketch. Describe the salient features of a simple close circuit grinding with a neat diagram what are the factors on which grinding efficiency depends?
Describe the working of a ball mill with respect to grinding forces critical speed of mill and power consumption and reduction ratio. What are Davis zones? Explain. Distinguish between screening and classification. Briefly explain laboratory sizing with graphical analysis. Define terminal velocity. Explain free setting and hindered setting ratios and their significance. Assume Newton’s law calculate the setting ratios of galena to quartz i) In Water ii) In a suspension of 20% quartz in water Specific gravity data: Galena : 7.5 Quartz : 2.65 Water : 1
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Code No.: NR-221804 II B.Tech II Semester Suppl. Examinations, April/May 2004 MINERAL DRESSING (Metallurgy and Material Technology) Time: 3 hours Max. Marks: 80 Answer any FIVE questions All questions carry equal marks --1. Discuss the procedure along with the equipment needed to determine the following: a) Liberation analysis for an one sample. b) Size analysis for one samples in the range below 50 µm.
Explain the terms ‘ratio of concentration’ and ‘recovery’ what is their use? In a concentration operation using a copper ore of 1.86 % copper a concentrate of 18.52 % copper is obtained by 9.3% by weight. Calculate the copper recovery percentage in the concentrate. What is jigging? Explain how stratification of mineral particles occure drawing jigging. What are the objectives of processing coal? With a typical flow sheet explain the different steps in a coal cleaning plant.
7.a) b)
Giving suitable examples explain the functions of various flotation segments Explain, with a simplified flow sheet of pb/zn/cu one, the steps involved in their concentration and separation.
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6.
8.
Write short notes on: a) Electrostatic separation. b) Magnetize separation. c) Flocculation and dispersion. d) Effectiveness of screen and factors affecting. $$$
Set No
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Code No.: NR-221804 II B.Tech II Semester Suppl. Examinations, April/May 2004 MINERAL DRESSING (Metallurgy and Material Technology) Time: 3 hours Max. Marks: 80 Answer any FIVE questions All questions carry equal marks --1.a) What is the necessity of sampling? Explain the methods adopted for sampling. b) State and explain the laws governing energy consumption during size reduction.
Compare and contrast the Blake and Dodge type of crushers with respect to design, working and applicability calculate the capacity of a Jaw crusher with a gape of 100cm and set of 10cm.
3.a)
What are the factors affecting the operation of grinding mills explain how they affect. What are autogenous grinding mills? What are their advantages?
4.a) b)
Define ‘capacity of screen’ what factors affect the capacity of screaming? Explain in detail State and explain ‘Stokes’ and ‘Newton’s’ laws. What is their significance in mineral is dressing? Assuming stokes law calculate the setting ratios of galena to quartz i) In Water ii) In a Suspension of 30% quartz in water Specific gravity date: Galena : 7.5 Quartz : 2.65 Water : 1
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2.
5.a) b)
Briefly explain the principles and application of jigging. Explain the terms: ratio of concentration, recovery and selectivity index of Pb is recovered in a concentrate by 95% and gange rejection in deleaded pulp is 96% Calculate selectivity index. What is the significance of selectivity index?
6.a)
Explain the principles of flotation Name the reagents used giving typical examples and explain how each reagent functions. Explain about the essential elements of design of magnetic separators.
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b)
Giving the objectives explain with a flow sheet the washing of coal. With a flow sheet explain concentration of lead – zinc ones.
8. a) b) c) d)
Write short notes on: Torthed roll crusher Sizing classifiers. Electrostatic separation Flocculation and dispersion
conical average diameter of 80 cm and width of discharge opening 10cm. 3.a) Compare open circuit versus closed circuit grinding. b) What are Davis zones?
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