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chemical engineering refractory technology MCQs

Practise multiple-choice questions from chemical engineering refractory technology for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering refractory technology Mcqs
1. Pyrometric cone equivalent (PCE) of a refractory is the measure of its_________________?
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A. Resistance to carbon monoxide attack

B. Resistance to slag penetration

C. Fusion point

D. Spalling resistance

2. With increasing alumina content, the fusion point of high alumina refractories__________________?
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A. Decreases

B. May increase or decrease; depends on its alumina content

C. Increases

D. Remain constant

3. Magnesite refractories have low resistance to___________________?
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A. Attack by basic slag

B. Abrasion

C. Disintegration on sudden change of temperature

D. Both B. and C.
4. What is the value of q for saturated liquid feed to a distillation column ?
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A. 0

B. <1

C. 1

D. >1

5. Carbon refractories are exclusively used in the_________________?
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A. Side wall of soaking pits

B. Regenerators of coke oven

C. Hearth of blast furnace

D. Walls of coke oven

6. Except _____________, all other refractories are bad conductors of electricity (i.e, have low electrical conductivity)?
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A. Chromite

B. Fireclay

C. Carborundum

D. Graphite
7. Which is a basic refractory ?
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A. Chrome magnesite

B. Fireclay

C. Silica

D. None of these

8. Silicon carbide refractories have very low ___________________?
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A. Refractoriness (< 1700C)

B. Thermal conductivity

C. Resistance to thermal shock

D. None of these
9. SiO2 percentage in firebrick is about____________________?
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A. > 94

B. 55-60

C. 80-85

D. 35-40

10. Refractoriness under load (RUL) is the most important property for the refractory bricks_________________?
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A. At the hearth bottom of the furnace on which stock is placed

B. Used for furnace insulation

C. Used in the roof of the furnace

D. None of these

11. Electrical resistor bars are made of _______________?
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A. Zirconia

B. Graphite

C. Silicon carbide

D. Alumina

12. Which of the following impurities reduces the refractoriness of magnesite bricks ?
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A. CaO

B. SiO2

C. Al2O3

D. All A., B. & C.
13. Hollow refractory bricks are made by___________________?
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A. Extrusion

B. pressing/machine moulding

C. Hand moulding

D. Slip casting
14. Which of the following bricks has the most close values of RUL and PCE ?
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A. Silica bricks

B. Fireclay bricks

C. High alumina bricks

D. Tar dolomite bricks

15. Carbon bricks are not used in the lining of the_________________?
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A. Highly chemical resistant equipments

B. Combustion chamber of blast furnace stoves

C. Blast furnace hearth

D. Electric furnaces

16. Furnace atmosphere for softening temperature determination of refractories (in which Seger Cones are placed) should be __________________?
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A. Oxidising

B. Either A. or B.

C. Neutral

D. Neither A. nor B.

17. Crushing strength of a refractory____________________?
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A. Is unaffected with change in service temperature

B. Increases with rise in service temperature

C. Decreases with rise in service temperature

D. Decreases with increase in porosity

18. Skull is not formed on the carbon blocks in the hearth of a blast furnace, when it becomes cold, because of its_______________?
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A. High thermal conductivity

B. None of these

C. High crushing strength

D. Non-wetting characteristic
19. Firing of refractory brick is done to __________________?
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A. duct

B. Develop stable mineral forms in them

C. All A., B. and C.

D. Dehydrate the dried refractory

E. Form ceramic bonds necessary for development of high crushing strength in the finished

20. Chrome magnesite bricks are used in the_________________?
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A. Copper melting furnaces & converters

B. Burner block of glass tanks

C. All A., B. and C.

D. Side walls of soaking pits and arc furnaces

21. Which of the following consumes the maximum tonnage of refractories annually in an integrated steel plant ?
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A. Reheating furnace

B. Soaking pits

C. Rotary lime kiln

D. L.D. converter
22. . Refractoriness under load (RUL) of fireclay bricks (under a load of 2 kg/cm2) is ______________ C?
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A. >2000

B. >1350

C. 500

D. 1000

23. Machine moulding of dry mixture of refractories requires a pressure of the order of _____________ kg/cm2?
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A. 1000

B. 10

C. 500

D. 100

24. Panel test determines the _____________ of refractories?
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A. Fusion point

B. Refractoriness under load (RUL)

C. Slag penetration resistance

D. Spalling resistance
25. Thoria__________________?
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A. Has high resistance to basic slags

B. All A., B. and C.

C. Which is expensive & radioactive, is used in crucibles for melting high purity metals

D. Has high fusion temperature (> 3000C) but poor resistance to thermal shock

26. Chrome magnesite bricks are_________________?
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A. Having higher RUL than silica bricks

B. Neutral in nature

C. Made by mixing 30% Chromite and 70% Periclase

D. Acidic in nature

27. Spray test determines the _____________ of refractories?
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A. Resistance to CO attack

B. Permanent linear change

C. RUL

D. Resistance to slag penetration
28. Which brick undergoes maximum shrinkage on drying ?
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A. Magnesite bricks

B. Fireclay bricks

C. Chromite bricks

D. Tar bonded dolomite bricks

29. High density refractory bricks have lower__________________?
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A. Spalling resistance

B. Slag penetration resistance

C. Fusion point

D. Thermal conductivity

30. Magnesite bricks are used in those parts of furnaces, which are __________________?
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A. Subjected to temperature fluctuation

B. Required to resist corrosive basic slag

C. None of these

D. Subjected to high load

31. Refractories are dried in the _______________?
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A. None of these

B. Sun

C. Rotary kilns

D. Tunnel kilns
32. Conversion of silica mineral to Cristobalite is accompanied by reduction in its ____________________?
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A. Volume

B. Specific gravity

C. Both A. & B.

D. Neither A. nor B.

33. Test piece for determination of RUL of a refractory is heated in a/an____________________?
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A. Oxidising atmosphere

B. Electric furnace

C. Reducing atmosphere

D. Neutral atmosphere

34. Spalling of a refractory means its____________________?
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A. Softening

B. Fracture due to uneven expansion at high temperature

C. Resistance to compressive loads

D. Resistance to chemical action of gases and molten fluxes

35. Porosity of silica bricks varies from ______________ percent?
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A. 5 to 10

B. 20 to 30

C. 60 to 75

D. 45 to 60

36. Fireclay refractories have __________________?
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A. Poor thermal spalling resistance

B. Very high cost

C. Tendency to expand unduly high during firing

D. Low co-efficient of thermal expansion
37. Ganister is a source of the ________________?
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A. Lime

B. Silica

C. Periclase

D. None of these

38. Refractoriness/fusion points of Superduty refractories is _______________ C?
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A. > 1730

B. > 2000

C. 1630-1670

D. 1520-1630

39. Which is the most stable crystalline form of silica at room temperature ?
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A. Cristobalite

B. None of these

C. Tridymite

D. Quartz
40. Chromite refractories_____________________?
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A. Are bonded with lime and clay

B. All A., B. and C.

C. (Free from silica) have better thermal fatigue resistance than silica and magnesite refractories.

D. Are resistant to basic slag

41. With increase in the porosity, thermal spalling resistance of fireclay brick___________________?
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A. Increases

B. Decreases

C. Remain same

D. May increase or decrease

42. Magnesite refractories are generally not used in the___________________?
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A. Open hearth furnace

B. Burning zone of cement kilns

C. Steel melting furnace

D. Electric furnace walls

43. Sillimanite is a _____________ refractory?
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A. Basic

B. Neutral

C. Insulating

D. High alumina
44. Roof of a basic open hearth furnace is lined with ______________ bricks?
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A. Dolomite

B. Silica

C. Magnesite

D. Fireclay

45. Dry mix hydraulic compositions of refractory aggregates with suitable bonding materials are called refractory_________________?
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A. None of these

B. Mortars

C. Castables

D. Cements

46. With increase in the density of silica refractories, its_______________?
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A. Resistance to slag attack increases

B. Spalling resistance reduces

C. Both A. and B.

D. Neither A. nor B.

47. Which furnace consumes maximum refractory annually in an integrated steel plant ?
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A. Soaking pit

B. Blast furnace

C. Coke ovens

D. L.D. converter
48. Silica refractories are not used in _________________?
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A. Beehive coke ovens

B. Dome and upper portion of B.F. stoves

C. Open hearth furnace roof

D. Coke oven walls

49. Because of its very high refractoriness of the order of __________ C, silicon carbide refractories are used in zinc smelting furnace, muffle furnace and for supporting the wares in tunnel kilns ?
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A. 1800

B. 2700

C. 2200

D. 2400

50. Silica refractories__________________?
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A. crack when subjected to sudden change of temperature

B. All A., B. and C.

C. Have lower thermal conductivity than fireclay bricks

D. Cannot be used in the dome of hot blast stoves