Refractory Technology

131. Refractory castables are used for

1. Producing monolithic linings
2. Patch work
3. Minimising the number of joints in the structure
4. All (A), (B) and (C)

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132. Refractory materials are never used in the construction of

1. Segar cones
2. Orton cones
3. Pressure vessels
4. Ovens & retorts

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133. Resistance to slag attack of a refractory

1. Depends on the nature of slag & refractory
2. Decreases at higher temperature
3. Decreases, if defective joints & cracks exist in the refractory
4. All (A), (B) and (C)

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134. Roof of a basic electric furnace is made of _________ bricks.

1. Superduty fireclay
2. Silica
3. Chromite
4. None of these

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135. Roof of a basic open hearth furnace is lined with _________ bricks.

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

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136. Rotary kilns meant for calcination of limestone are lined with chrome magnesite in _________ zone.

1. Preheating
2. Cooling
3. Burning
4. All the above

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137. RUL of refractories depends on the

1. Chemical composition
2. Physical structure
3. Presence of impurities like iron & alkali
4. All (A), (B) and (C)

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138. Segar cones are used for the determination of _________ of refractories.

1. Softening temperature
2. Spalling resistance
3. Electrical conductivity
4. Resistance to slag attack

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139. Semi-silica bricks compared to silica bricks have

1. Less fusion point
2. Better spalling resistance
3. Both (A) and (B)
4. Neither (A) not (B)

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140. Si percentage in silica refractories used in the walls of coke oven is about

1. 45
2. 60
3. 80
4. 95

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