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Chemical Engineering :: Refractory Technology

  1. Refractoriness under load (RUL) of fireclay bricks (under a load of 2 kg/cm2 ) is __________ °C.

  2. A.
    500
    B.
    1000
    C.
    >1350
    D.
    >2000

  3. __________ of carbon blocks in the hearth of blast furnace helps in avoiding skull formation, when it becomes cold.

  4. A.
    High thermal conductivity
    B.
    Low porosity
    C.
    Non-wetting characteristics
    D.
    High density

  5. Bauxite calcining rotary kilns are lined with __________ bricks.

  6. A.
    fireclay
    B.
    carbon
    C.
    85% alumina
    D.
    corundum

  7. Use of higher percentage of lime for bonding silica bricks, reduces their

  8. A.
    strength
    B.
    abrasion resistance
    C.
    both (a) & (b)
    D.
    neither (a) nor (b)

  9. Grog addition in fireclay during brick manufacture is done to

  10. A.
    reduce its shrinkage on heating.
    B.
    impart greater spalling resistance.
    C.
    enhance the strength of fired refractories.
    D.
    all (a), (b) and (c).

  11. To resist spalling tendency, a refractory should have

  12. A.
    greater diffusivity.
    B.
    low specific heat.
    C.
    low thermal co-efficient of expansion.
    D.
    all (a), (b) and (c).

  13. Cold crushing strength of fireclay bricks is about __________ kgf/cm2.

  14. A.
    50-100
    B.
    100-150
    C.
    200-400
    D.
    500-1000

  15. Spalling tendency of refractories is reduced by increasing its

  16. A.
    porosity
    B.
    specific gravity
    C.
    thermal conductivity
    D.
    strength

  17. Carbon refractories are exclusively used in the

  18. A.
    hearth of blast furnace.
    B.
    walls of coke oven.
    C.
    regenerators of coke oven.
    D.
    side wall of soaking pits.

  19. Spalling of a refractory means its

  20. A.
    softening.
    B.
    fracture due to uneven expansion at high temperature.
    C.
    resistancce to compressive loads.
    D.
    resistance to chemical action of gases and molten fluxes.