With increase in the density of silica refractories, its_______________?

Resistance to slag attack increases

With increasing alumina content, the fusion point of high alumina refractories__________________?

May increase or decrease; depends on its alumina content

Zircon refractories have__________________?

High RUL (1600°C) and refractoriness (> 2000°C)

Zirconia refractories are not used in_____________________?

High frequency induction furnaces in the form of inductors

Making sheaths for thermocouple

Lining high temperature ceramic kilns

Furnaces subjected to fluctuating temperature

High frequency induction furnaces in the form of inductors

Zirconia refractory_________________?

Does not react with basic slags

Has poor electrical conductivity at high temperature

To resist spalling tendency, a refractory should have________________?

Low thermal co-efficient of expansion

Thoria__________________?

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

Has high resistance to basic slags

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

Thoria is an expensive refractory material and is radioactive in nature. Thorium oxide is used in the manufacture of______________?

Crucibles used for melting of high purity metals

Thermal conductivity of refractory bricks_________________?

Decreases with decreases in porosity

Increases with decrease in porosity

Decreases with decreases in porosity

Is independent of its porosity and is maximum for insulating bricks

Increases with the amount of air entrapped in pores

RUL of refractories depends on the _____________________?

Presence of impurities like iron & alkali

Resistance to slag attack of a refractory _____________________?

Depends on the nature of slag & refractory

Decreases at higher temperature

Decreases, if defective joints & cracks exist in the refractory

Refractory castables are used for__________________?

Minimising the number of joints in the structure

Refractoriness under load (RUL) is the most important property for the refractory bricks_________________?

At the hearth bottom of the furnace on which stock is placed

Used in the roof of the furnace

Rate of slag attack on refractories increases with rise in temperature due to the___________________?

Increased thermal conductivity of brick

Oxidising condition in the furnace

Ramming masses are used for____________________?

Obtaining monolithic working faces

Repairing construction of various furnace parts

Quartz is___________________?

Stable form of silica upto 870°C

Converted to Tridymite on firing between 870 to 1470°C

Transformed to Cristobalite on heating above 1470°C

163 + Mcqs in Refractory Technology for Chemical in Chemical Engineering Page 1 McqOptions

1.	Which one contains minimum percentage of SiO2 ?
A.	Firebrick
B.	Sillimanite
C.	Semi-silica
D.	Aluminous firebrick
Answer» C. Semi-silica

Discussion

2.	With decrease in porosity, the ______________ of the refractories decreases?
A.	Strength
B.	Thermal conductivity
C.	Spalling resistance
D.	None of these
Answer» D. None of these

Discussion

3.	With increase in the alumina content in firebricks, its fusion point (refractoriness) ?
A.	Decreases linearly
B.	Remains unchanged
C.	Increases
D.	Decreases
Answer» D. Decreases

Discussion

4.	With increase in the alumina content, the refractoriness of high alumina refractories_______________?
A.	Increases
B.	Decreases
C.	Remain same
D.	May increase or decrease
Answer» B. Decreases

Discussion

5.	With increase in the density of silica refractories, its_______________?
A.	Resistance to slag attack increases
B.	Spalling resistance reduces
C.	Both A. and B.
D.	Neither A. nor B.
Answer» D. Neither A. nor B.

Discussion

6.	With increase in the porosity, thermal spalling resistance of fireclay brick___________________?
A.	Increases
B.	Decreases
C.	Remain same
D.	May increase or decrease
Answer» B. Decreases

Discussion

7.	With increasing alumina content, the fusion point of high alumina refractories__________________?
A.	Increases
B.	Decreases
C.	Remain constant
D.	May increase or decrease; depends on its alumina content
Answer» B. Decreases

Discussion

8.	Zircon refractories have__________________?
A.	Low co-efficient of expansion
B.	High RUL (1600°C) and refractoriness (> 2000°C)
C.	High spalling resistance
D.	All A., B. and C.
Answer» E.

Discussion

9.	Zirconia refractories are not used in_____________________?
A.	Making sheaths for thermocouple
B.	Lining high temperature ceramic kilns
C.	Furnaces subjected to fluctuating temperature
D.	High frequency induction furnaces in the form of inductors
Answer» D. High frequency induction furnaces in the form of inductors

Discussion

10.	Zirconia refractory_________________?
A.	Does not react with basic slags
B.	Is produced from baddeleyite
C.	Cannot be used as an insulator
D.	Has poor electrical conductivity at high temperature
Answer» C. Cannot be used as an insulator

Discussion

11.	Which of the following bricks should not be used, if the furnace is to be used intermittently ?
A.	Firebricks
B.	Silica bricks
C.	Silicon carbide bricks
D.	Sillimanite
Answer» C. Silicon carbide bricks

Discussion

12.	Which is not an alumino-silicate refractory ?
A.	Fireclay bricks
B.	Mullite bricks
C.	Tar dolomite bricks
D.	High alumina bricks
Answer» D. High alumina bricks

Discussion

13.	Which is not a natural insulating material ?
A.	Diatomaceous earth/kieselgur
B.	Asbestos
C.	Vermiculite
D.	None of these
Answer» E.

Discussion

14.	What is the value of ‘q’ for saturated liquid feed to a distillation column ?
A.	0
B.	<1
C.	1
D.	>1
Answer» D. >1

Discussion

15.	Water content in ground refractory material to be shaped into bricks by hand moulding is about ______________ percent?
A.	5
B.	20
C.	40
D.	55
Answer» C. 40

Discussion

16.	Walls, roofs & combustion chambers of annealing furnaces are made of ______________ bricks?
A.	High duty fireclay
B.	Silica
C.	Mullite
D.	Carborundum
Answer» B. Silica

Discussion

17.	Vacuum steel degassing units are lined with__________________?
A.	Silica bricks
B.	Low duty firebricks
C.	High alumina bricks
D.	Graphite blocks
Answer» D. Graphite blocks

Discussion

18.	Use of higher percentage of lime for bonding silica bricks, reduces their__________________?
A.	Strength
B.	Abrasion resistance
C.	Both A. & B.
D.	Neither A. nor B.
Answer» D. Neither A. nor B.

Discussion

19.	Upper portion of hot metal mixer are lined with mullite bricks, which helps in resisting the_________________?
A.	Washing action of metal
B.	Corrosion by layer of slag
C.	Both A. & B.
D.	Neither A. nor B.
Answer» B. Corrosion by layer of slag

Discussion

20.	To resist spalling tendency, a refractory should have________________?
A.	Greater diffusivity
B.	Low specific heat
C.	Low thermal co-efficient of expansion
D.	All A., B. and C.
Answer» E.

Discussion

21.	Thoria__________________?
A.	Has high fusion temperature (> 3000°C) but poor resistance to thermal shock
B.	Has high resistance to basic slags
C.	Which is expensive & radioactive, is used in crucibles for melting high purity metals
D.	All A., B. and C.
Answer» E.

Discussion

22.	Thoria is an expensive refractory material and is radioactive in nature. Thorium oxide is used in the manufacture of______________?
A.	Segar cones
B.	Muffles for muffle furnaces
C.	Insulating bricks
D.	Crucibles used for melting of high purity metals
Answer» E.

Discussion

23.	Thermal spalling mainly occurs during _____________ of furnaces?
A.	Cooling down
B.	Warming up
C.	Both A. & B.
D.	Neither A. nor B.
Answer» D. Neither A. nor B.

Discussion

24.	Thermal diffusivity of a refractory brick is high, when its ____________ is high?
A.	Density
B.	Specific heat
C.	Thermal conductivity
D.	None of these
Answer» D. None of these

Discussion

25.	Thermal conductivity of refractory bricks_________________?
A.	Increases with decrease in porosity
B.	Decreases with decreases in porosity
C.	Is independent of its porosity and is maximum for insulating bricks
D.	Increases with the amount of air entrapped in pores
Answer» B. Decreases with decreases in porosity

Discussion

26.	The maximum linear expansion of silica bricks during firing is about ______________ percent?
A.	0.5
B.	1
C.	2
D.	3.5
Answer» E.

Discussion

27.	The main raw material for manufacture of silicon carbide refractories is_________________?
A.	Corundum
B.	Carborundum
C.	Bauxite
D.	Periclase
Answer» C. Bauxite

Discussion

28.	The linear thermal expansion of _______________ bricks upto 1000 °C is very low of the order of ≤ 0.5 percent?
A.	Fireclay
B.	Silica
C.	Magnesite
D.	Corundum
Answer» B. Silica

Discussion

29.	The largest consumer of refractories is the _______________ industry?
A.	Cement
B.	Metallurgical
C.	Fertiliser
D.	Power
Answer» C. Fertiliser

Discussion

30.	The highest melting pure oxide (m.p. > 3000°C)is___________________?
A.	Thoria
B.	Alumina
C.	Beryllia
D.	Zirconia
Answer» B. Alumina

Discussion

31.	RUL of refractories depends on the _____________________?
A.	Chemical composition
B.	Physical structure
C.	Presence of impurities like iron & alkali
D.	All A., B. and C.
Answer» E.

Discussion

32.	Rotary kilns meant for calcination of limestone are lined with chrome magnesite in ______________ zone?
A.	Preheating
B.	Cooling
C.	Burning
D.	All the above
Answer» D. All the above

Discussion

33.	Roof of a basic open hearth furnace is lined with ______________ bricks?
A.	Silica
B.	Fireclay
C.	Dolomite
D.	Magnesite
Answer» B. Fireclay

Discussion

34.	Roof of a basic electric furnace is made of _____________ bricks?
A.	Superduty fireclay
B.	Silica
C.	Chromite
D.	None of these
Answer» C. Chromite

Discussion

35.	Resistance to slag attack of a refractory _____________________?
A.	Depends on the nature of slag & refractory
B.	Decreases at higher temperature
C.	Decreases, if defective joints & cracks exist in the refractory
D.	All A., B. and C.
Answer» E.

Discussion

36.	Refractory materials are never used in the construction of _________________?
A.	Segar cones
B.	Orton cones
C.	Pressure vessels
D.	Ovens & retorts
Answer» D. Ovens & retorts

Discussion

37.	Refractory castables are used for__________________?
A.	Producing monolithic linings
B.	Patch work
C.	Minimising the number of joints in the structure
D.	All A., B. and C.
Answer» E.

Discussion

38.	Refractory bricks with lower permeability is produced by using __________________?
A.	Higher firing temperature
B.	Higher moulding pressure
C.	Finer grog size
D.	All A., B. and C.
Answer» E.

Discussion

39.	Refractoriness under load (RUL) of fireclay bricks (under a load of 2 kg/cm2) is ______________ °C?
A.	500
B.	1000
C.	>1350
D.	>2000
Answer» D. >2000

Discussion

40.	Refractory bricks having lower porosity have_________________________?
A.	High insulating properties
B.	Low heat capacity
C.	Low thermal conductivity
D.	Greater strength
Answer» E.

Discussion

41.	Refractoriness/fusion points of ‘Superduty’ refractories is _______________ °C?
A.	1520-1630
B.	1630-1670
C.	> 1730
D.	> 2000
Answer» D. > 2000

Discussion

42.	Refractoriness of a typical silica brick corresponds to Segar cone number, ’32’, which is equivalent to a temperature of _____________ °C?
A.	1380
B.	1520
C.	1710
D.	1915
Answer» D. 1915

Discussion

43.	Refractoriness under loads (RUL) is quite close to the fusion temperature (PCE) for _____________ bricks?
A.	Fireclay
B.	Silica
C.	Dolomite
D.	Very low alumina
Answer» C. Dolomite

Discussion

44.	Refractoriness under load (RUL) is the most important property for the refractory bricks_________________?
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
Answer» B. Used for furnace insulation

Discussion

45.	Refractories subjected to alternate cycles of heating & cooling are liable to loose their resistance to__________________?
A.	Thermal spalling
B.	Slag attack
C.	Fusion under load
D.	CO attack
Answer» B. Slag attack

Discussion

46.	Refractories are dried in the _______________?
A.	Rotary kilns
B.	Tunnel kilns
C.	Sun
D.	None of these
Answer» C. Sun

Discussion

47.	Rate of slag attack on refractories increases with rise in temperature due to the___________________?
A.	Decreased viscosity of slag
B.	Increased thermal conductivity of brick
C.	Oxidising condition in the furnace
D.	None of these
Answer» B. Increased thermal conductivity of brick

Discussion

48.	Ramming masses are used for____________________?
A.	Obtaining monolithic working faces
B.	Repairing construction of various furnace parts
C.	Both A. & B.
D.	Neither A. nor B.
Answer» D. Neither A. nor B.

Discussion

49.	Quartz is___________________?
A.	Stable form of silica upto 870°C
B.	Converted to Tridymite on firing between 870 to 1470°C
C.	Transformed to Cristobalite on heating above 1470°C
D.	All A., B. and C.
Answer» E.

Discussion

50.	Pyrometric cone equivalent (PCE) value (Segar cone) of ‘Superduty refractories’ is more than 33 which corresponds to a temperature of _____________ °C?
A.	1520
B.	1630
C.	1670
D.	1730
Answer» E.

Discussion

Explore topic-wise MCQs in Chemical Engineering.

Which one contains minimum percentage of SiO2 ?

With decrease in porosity, the ______________ of the refractories decreases?

With increase in the alumina content in firebricks, its fusion point (refractoriness) ?

With increase in the alumina content, the refractoriness of high alumina refractories_______________?

With increase in the density of silica refractories, its_______________?

With increase in the porosity, thermal spalling resistance of fireclay brick___________________?

With increasing alumina content, the fusion point of high alumina refractories__________________?

Zircon refractories have__________________?

Zirconia refractories are not used in_____________________?

Zirconia refractory_________________?

Which of the following bricks should not be used, if the furnace is to be used intermittently ?

Which is not an alumino-silicate refractory ?

Which is not a natural insulating material ?

What is the value of ‘q’ for saturated liquid feed to a distillation column ?

Water content in ground refractory material to be shaped into bricks by hand moulding is about ______________ percent?

Walls, roofs & combustion chambers of annealing furnaces are made of ______________ bricks?

Vacuum steel degassing units are lined with__________________?

Use of higher percentage of lime for bonding silica bricks, reduces their__________________?

Upper portion of hot metal mixer are lined with mullite bricks, which helps in resisting the_________________?

To resist spalling tendency, a refractory should have________________?

Thoria__________________?

Thoria is an expensive refractory material and is radioactive in nature. Thorium oxide is used in the manufacture of______________?

Thermal spalling mainly occurs during _____________ of furnaces?

Thermal diffusivity of a refractory brick is high, when its ____________ is high?

Thermal conductivity of refractory bricks_________________?

The maximum linear expansion of silica bricks during firing is about ______________ percent?

The main raw material for manufacture of silicon carbide refractories is_________________?

The linear thermal expansion of _______________ bricks upto 1000 °C is very low of the order of ≤ 0.5 percent?

The largest consumer of refractories is the _______________ industry?

The highest melting pure oxide (m.p. > 3000°C)is___________________?

RUL of refractories depends on the _____________________?

Rotary kilns meant for calcination of limestone are lined with chrome magnesite in ______________ zone?

Roof of a basic open hearth furnace is lined with ______________ bricks?

Roof of a basic electric furnace is made of _____________ bricks?

Resistance to slag attack of a refractory _____________________?

Refractory materials are never used in the construction of _________________?

Refractory castables are used for__________________?

Refractory bricks with lower permeability is produced by using __________________?

Refractoriness under load (RUL) of fireclay bricks (under a load of 2 kg/cm2) is ______________ °C?

Refractory bricks having lower porosity have_________________________?

Refractoriness/fusion points of ‘Superduty’ refractories is _______________ °C?

Refractoriness of a typical silica brick corresponds to Segar cone number, ’32’, which is equivalent to a temperature of _____________ °C?

Refractoriness under loads (RUL) is quite close to the fusion temperature (PCE) for _____________ bricks?

Refractoriness under load (RUL) is the most important property for the refractory bricks_________________?

Refractories subjected to alternate cycles of heating & cooling are liable to loose their resistance to__________________?

Refractories are dried in the _______________?

Rate of slag attack on refractories increases with rise in temperature due to the___________________?

Ramming masses are used for____________________?

Quartz is___________________?

Pyrometric cone equivalent (PCE) value (Segar cone) of ‘Superduty refractories’ is more than 33 which corresponds to a temperature of _____________ °C?