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Chemical Engineering :: Refractory Technology

  1. Skull is not formed on the carbon blocks in the hearth of a blast furnace, when it becomes cold, becaus of its

  2. A.
    non-wetting characteristic.
    B.
    high thermal conductivity.
    C.
    high crushing strength.
    D.
    none of these.

  3. Firing temperature of magnesite bricks is about __________ °C.

  4. A.
    800-1000
    B.
    1000-1200
    C.
    1600-1800
    D.
    2400-2600

  5. Hollow refractory bricks are made by

  6. A.
    slip casting
    B.
    hand moulding
    C.
    pressing/machine moulding
    D.
    extrusion

  7. Quartz is

  8. A.
    stable form of silica upto 870°C.
    B.
    converted to tridymite on firing between 870 to 1470°C.
    C.
    transformed to crystoballite on heating above 1470°C.
    D.
    all (a), (b) and (c).

  9. An indication of degree of firing in silica brick is its

  10. A.
    specific gravity
    B.
    fusion point
    C.
    RUL
    D.
    none of these

  11. Panel test determines the __________ of refractories.

  12. A.
    fusion point
    B.
    spalling resistance
    C.
    slag penetration resistance
    D.
    refractoriness under load (RUL)

  13. Fireclay bricks are not used in the

  14. A.
    beehive coke oven.
    B.
    by-product coke oven walls.
    C.
    combustion chamber of B.F. stoves.
    D.
    coke oven regenerators.

  15. Fusion point of a basic refractory material is

  16. A.
    reduced by the addition of acid oxides.
    B.
    increased by the addition of acid oxides.
    C.
    not affected by the addition of acid oxides.
    D.
    always less than 1000°C.

  17. RUL of refractories depends on the

  18. A.
    chemical composition.
    B.
    physical structure.
    C.
    presence of impurities like iron & alkali.
    D.
    all (a), (b) and (c).

  19. Which is the stable form of silica between 1470°C and the melting point 1713°C ?

  20. A.
    Cristobalite
    B.
    Tridymite
    C.
    Quartz
    D.
    None of these