Refractory Technology

81. Hot metal runner in blast furnace are lined with _________ bricks.

1. Silica
2. Carborundum
3. Fireclay
4. Magnesite

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82. In chemical process equipments, the conical bottom heads used, usually has an apex angle of

1. 20°
2. 40°
3. 60°
4. 80°

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83. In panel test for spalling resistance, the average face temperature of panel assembly is maintained at _________ °C for 24 hours.

1. 700
2. 1000
3. 1600
4. 2000

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84. Insulating refractories should have

1. High porosity
2. Low thermal conductivity
3. Both (A) and (B)
4. Neither (A) not (B)

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85. Lessing ring is formed by the addition of a partition across the centre of a raschig ring, which results in an area increase of about _________ percent.

1. 5
2. 20
3. 35
4. 55

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86. Lower part of hot metal mixer are lined with _________ bricks.

1. Superduty fireclay
2. High alumina
3. Silica
4. Carborundum

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87. Machine moulding of dry mixture of refractories requires a pressure of the order of _________ kg/cm2.

1. 10
2. 100
3. 500
4. 1000

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88. Magnesite bricks are used in those parts of furnaces, which are

1. Subjected to temperature fluctuation
2. Required to resist corrosive basic slag
3. Subjected to high load
4. None of these

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89. Magnesite bricks have poor resistance to attack by _________ slag.

1. Lime
2. Basic
3. Acid
4. None of these

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90. Magnesite chrome bricks are used in the

1. Roof lining of basic open hearth & other basic furnaces
2. Reheating furnaces
3. Soaking pits
4. All (A), (B) and (C)

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