chemical engineering refractory technology MCQs – Page 9

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 Review each marked answer and report any item that may be outdated or unclear.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
161. Basic bricks are not made of ___________________?
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A. Forsterite

B. Fireclay

C. Chromite

D. Magnesite

162. Resistance to slag attack of a refractory _____________________?
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A. Decreases, if defective joints & cracks exist in the refractory

B. Decreases at higher temperature

C. All A., B. and C.

D. Depends on the nature of slag & refractory

163. Cold crushing strength of refractories depends upon its_________________?
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A. Texture

B. Composition

C. Firing temperature

D. All A., B. and C.
164. Most Cermets, which normally have high thermal conductivity and high thermal shock resistance, comprises of ceramic & metallic components of ______________ percent respectively?
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A. 80 and 20

B. 50 and 50

C. 60 and 40

D. 20 and 80

165. Mixing of ground refractory material and water is done in a ______________ mill?
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A. Pug

B. Ball

C. Tube

D. Rod

166. Magnesite refractories are used for the construction of those furnaces, which are________________?
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A. Not required to resist the corrosive action of basic slag

B. Not subjected to fluctuation in temperature

C. Used for raising & maintaining high temperature

D. Both B. and C.
167. ____________ of carbon blocks in the hearth of blast furnace helps in avoiding skull formation, when it becomes cold?
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A. High density

B. Non-wetting characteristics

C. Low porosity

D. High thermal conductivity

168. Natural silica___________________?
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A. Transforms to other allotropic forms i.e. Tridymite and Cristobalite involving very high

B. ume changes

C. All A., B. and C.

D. Mainly contains quartz

E. Is not stable at high temperature

169. Spalling resistance of a refractory cannot be increased by ____________________?
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A. Increasing its porosity

B. Decreasing its thermal co-efficient of expansion

C. Using a coarser grog during its manufacture

D. Making it denser
170. Maximum apparent porosity of magnesite bricks is about _____________ percent?
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A. 8

B. 24

C. 58

D. 44

171. Which one expands on heating ?
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A. Silica bricks

B. Fireclay bricks

C. Both A. & B.

D. Neither A. nor B.

172. Which is not an alumino-silicate refractory ?
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A. Mullite bricks

B. Fireclay bricks

C. High alumina bricks

D. Tar dolomite bricks
173. Maximum shrinkage in volume occurring during burning/firing of dried refractories may be as high as ______________ percent?
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A. 10

B. 15

C. 20

D. 30
174. Fireclay bricks are never used in the______________?
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A. Coke oven walls

B. Beehive oven

C. Lead blast furnace

D. Zinc roaster

175. Lower part of hot metal mixer are lined with _____________ bricks?
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A. Superduty fireclay

B. Silica

C. High alumina

D. Carborundum
176. In panel test for spalling resistance, the average face temperature of panel assembly is maintained at ______________ C for 24 hours?
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A. 2000

B. 700

C. 1600

D. 1000

177. Pick out the wrong statement ?
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A. For reducing spalling tendency, the refractory should be well fired and its porosity should be

B. Refractories used in muffle furnace should have low thermal conductivity

C. e

D. Refractoriness under load (RUL) of a refractory is always less than its refractoriness

E. The electrical resistivity of refractories drops rapidly with rise in temperature

178. Highest melting (m.p = 3070C) oxide refractory is__________________?
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A. Zirconia

B. Magnesia

C. Thoria

D. Alumina

179. Thermal conductivity of refractory bricks_________________?
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A. Is independent of its porosity and is maximum for insulating bricks

B. Decreases with decreases in porosity

C. Increases with the amount of air entrapped in pores

D. Increases with decrease in porosity
180. Refractory bricks with lower permeability is produced by using __________________?
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A. Finer grog size

B. Higher moulding pressure

C. Higher firing temperature

D. All A., B. and C.