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Chemical Engineering :: Refractory Technology

  1. Maximum water percentage in refractory mix meant for hand moulding may be as high as __________ percent.

  2. A.
    2-3
    B.
    5-7
    C.
    7-12
    D.
    14-20

  3. Fireclay bricks are never used in the

  4. A.
    beehive oven
    B.
    coke oven walls
    C.
    zinc roaster
    D.
    lead blast furnace

  5. With increasing alumina content, the fusion point of high alumina refractories

  6. A.
    increases.
    B.
    decreases.
    C.
    remains constant.
    D.
    may increase or decrease ; depends on its alumina content.

  7. Chrome magnesite bricks are used in the

  8. A.
    side walls of soaking pits and arc furnaces.
    B.
    copper melting furnaces & converters.
    C.
    burner block of glass tanks.
    D.
    all (a), (b) and (c)

  9. Machine moulding of dry mixture of refractories requires a pressure of the order of __________ kg/cm2.

  10. A.
    10
    B.
    100
    C.
    500
    D.
    1000

  11. Except __________ , all other refractories are bad conductors of electricity (i.e, have low electrical conductivity).

  12. A.
    fireclay
    B.
    carborundum
    C.
    graphite
    D.
    chromite

  13. Which refractory must have controlled atmosphere (temperature and humidity) for its safe storage ?

  14. A.
    Tar bonded dolomite bricks
    B.
    Fireclay bricks
    C.
    Mullite bricks
    D.
    Magnesite bricks

  15. Alumina-graphite bricks are used for lining the

  16. A.
    slide gate in teeming laddies.
    B.
    continuous casting systems.
    C.
    both (a) and (b).
    D.
    neither (a) nor (b).

  17. Spalling resistance of a refractory can not be increased by

  18. A.
    increasing its porosity.
    B.
    using a coarser grog during its manufacture.
    C.
    decreasing its thermal co-efficient of expansion.
    D.
    making it denser.

  19. Fireclay refractories have

  20. A.
    low co-efficient of thermal expansion.
    B.
    poor thermal spalling resistance.
    C.
    tendency to expand unduly high during firing.
    D.
    very high cost.