chemical engineering refractory technology MCQs – Page 4

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 Review each marked answer and report any item that may be outdated or unclear.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
61. Colour of fireclay bricks is_________________?
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A. Yellow

B. Black

C. Light buff to reddish buff

D. None of these

62. Maximum alumina content in high alumina refractory can be as high as _____________ percent?
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A. 70

B. 90

C. 30

D. 50

63. High porosity refractory bricks have _______________?
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A. Better thermal spalling resistance

B. Poor resistance to the penetration of molten slag, metal & flue gases

C. Poor heat conductivity & low strength

D. All A., B. and C.
64. _____________ is not a single oxide-refractory?
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A. Magnesia

B. Silicon carbide

C. None of these

D. Zirconia

65. PCE value (Segar cone) of Superduty refractories is more than 33, which is equivalent to a temperature of ____________ C?
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A. 1730

B. 1670

C. 1630

D. 1520

66. Magnesite chrome refractories____________________?
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A. Are not at all resistant to the corrosive action of iron oxide

B. Have very low (50 kg/cm2) cold crushing strength (C.C.S.), and cannot be used in metalcase

C. Have better spalling resistance than chrome magnesite refractories

D. Have very low thermal co-efficient of expansion

E. m

67. High refractoriness of refractory bricks means, that it has a________________?
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A. High spalling resistance

B. Low spalling resistance

C. High resistance to fusion

D. Low porosity

68. Which is the stable form of silica between 1470C and the melting point 1713C ?
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A. None of these

B. Cristobalite

C. Quartz

D. Tridymite

69. Which of the following bricks should not be used, if the furnace is to be used intermittently ?
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A. Silicon carbide bricks

B. Sillimanite

C. Firebricks

D. Silica bricks
70. Presence of MgO in alumino-silicate refractories _______________ its refractoriness?
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A. Lowers

B. Does not affect

C. Increases

D. Either A. or B.; depends on its quantity

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

B. Muffles for muffle furnaces

C. Insulating bricks

D. Crucibles used for melting of high purity metals
72. Roof of a basic electric furnace is made of _____________ bricks?
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A. None of these

B. Superduty fireclay

C. Silica

D. Chromite

73. Which refractory must have controlled atmosphere (temperature and humidity) for its safe storage ?
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A. Mullite bricks

B. Tar bonded dolomite bricks

C. Fireclay bricks

D. Magnesite bricks

74. Semi-silica bricks compared to silica bricks have_______________?
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A. Less fusion point

B. Better spalling resistance

C. Both A. and B.

D. Neither A. not B.

75. Which is the stable form of silica below 870C ?
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A. Cristobalite

B. None of these

C. Tridymite

D. Quartz
76. Tar bonded dolomite bricks__________________?
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A. Have poorer hydration resistance than pitch bonded bricks

B. All A., B. and C.

C. Are used in outer lining of L.D. converters

D. Are stored under controlled temperature & humidity to avoid hydration

77. An ideal refractory should have high__________________?
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A. Fusion point

B. Spalling rate

C. None of these

D. Shrinkage ability

78. Carbon refractories_____________________?
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A. Do not resist temperature fluctuations

B. Have extremely low thermal & electrical conductivities

C. Are not attacked by slags, as they are not wetted by melts

D. Do not burn/oxidise, when exposed to air on heating

79. Chrome magnesite is not used in the ____________________?
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A. Inner lining of L.D. converter

B. Wear out lining of steel melting furnaces

C. Aluminium melting furnaces

D. All A., and B. and C.

80. High thermal conductivity of a refractory material is not important, when it is to be used in the______________________?
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A. Coke oven regenerators

B. Muffle furnace

C. Recuperators

D. Blast furnace