3426. Upper portion of hot metal mixer are lined with mullite bricks, which helps in resisting the
washing action of metal.
corrosion by layer of slag.
both (a) & (b).
neither (a) nor (b).
✅ The correct answer is option A.
3431. Presence of MgO in alumino-silicate refractories __________ its refractoriness.
increases
lowers
does not affect
either (a) or (b); depends on its quantity
✅ The correct answer is option B.
3433. Pyrometric cone equivalent (PCE) value (Segar cone) of ‘superduty refractories’ is more than 33 which corresponds to a temperature of __________ °C.
1520
1630
1670
1730
✅ The correct answer is option D.
3438. Firing temperature of magnesite bricks is about __________ °C.
800-1000
1000-1200
1600-1800
2400-2600
✅ The correct answer is option C.
3443. Fusion point of a basic refractory material is
reduced by the addition of acid oxides.
increased by the addition of acid oxides.
not affected by the addition of acid oxides.
always less than 1000°C.
✅ The correct answer is option A.
3409. Pyrometric cone equivalent (PCE) of a refractory is the measure of its
spalling resistance.
fusion point.
resistance to slag penetration.
resistance to carbon monoxide attack.
✅ The correct answer is option B.
3411. Which property of refractories is the most important for top section of the blast furnace?
Resistance to abrasion.
Resistance to slag peneration.
Stability of volume at high temperature.
Resistance to corrosion by slag.
✅ The correct answer is option A.
3415. Basic bricks are not made of
fireclay
magnesite
foresterite
chromite
✅ The correct answer is option A.
3420. Furnace atmosphere for softening temperature determination of refractories (in which segar cones are placed) should be
oxidising
neutral
either (a) or (b)
neither (a) nor (b)
✅ The correct answer is option C.
3424. Fusion point of an acidic refractory material is
increased by the addition of basic oxides.
reduced by the addition of basic oxides.
not affected by the addition of basic oxides.
always more than 2500°C.
✅ The correct answer is option B.