Free Chemical Process Principles MCQs with Answers

• A. 700
• B. 1000
• C. 1600
• D. 2000

Explanation: In the panel spalling test, the refractory panel is exposed to a severe high-temperature cycle, with its average face temperature…

• A. Cupola
• B. Gas producer
• C. Roof of open hearth furnace
• D. Bottom of hot metal mixer

Explanation: The bottom of a hot-metal mixer is exposed to molten iron and basic slags, so it requires basic refractories such as magnesite rather than…

• A. 10-25
• B. 5-10
• C. 25-35
• D. 35-50

Explanation: Fireclay refractories are relatively porous, commonly having about 10 to 25% porosity.

• A. Less load bearing capacity
• B. High resistance to thermal shock and creep
• C. Low refractoriness
• D. Less resistance to slag attack

Explanation: High-alumina bricks withstand high temperatures, creep and slag attack better than ordinary fireclay bricks.

• A. Al2O3. 2SiO2
• B. Al2O3. SiO2
• C. 3Al2O3. 2SiO2
• D. 2Al2O3. 3SiO2

Explanation: Mullite is the aluminosilicate compound 3Al2O3·2SiO2. It is valued in refractories for its high-temperature stability and low expansion.

• A. 55
• B. 70
• C. 80
• D. 90

Explanation: High-grade bauxite can provide roughly 85 to 90% alumina after processing, so the maximum listed value is 90%.

• A. Firebrick
• B. Sillimanite
• C. Semi-silica
• D. Aluminous firebrick

Explanation: Sillimanite, Al2O3·SiO2, contains about 36.5% SiO2, less than ordinary firebrick and semi-silica brick.

• A. Porosity
• B. Specific gravity
• C. RUL
• D. Thermal conductivity

Explanation: Refractoriness under load, or RUL, measures how well a refractory retains strength and resists deformation under simultaneous temperature…

• A. Kyanite
• B. Sillimanite
• C. Diaspore
• D. Periclase

Explanation: Periclase is essentially magnesium oxide, MgO, and is therefore a basic magnesia refractory rather than a high-alumina material.

• A. None of these
• B. Asbestos
• C. Vermiculite
• D. Diatomaceous earth/kieselgur

Explanation: Diatomaceous earth, asbestos and vermiculite are all naturally occurring insulating materials.

• A. Lime
• B. Basic
• C. Acid
• D. None of these

Explanation: Magnesite is a basic refractory and is compatible with basic slags, but acidic slags attack it.

• A. Tar dolomite
• B. Fireclay
• C. Silica
• D. Carbon

Explanation: Carbon refractories oxidise readily in an oxidising atmosphere, producing CO or CO2 and losing their structure.

• A. Spalling resistance
• B. Thermal conductivity
• C. Strength
• D. None of these

Explanation: Lower porosity usually improves strength and thermal conductivity but reduces the ability of a refractory to absorb sudden thermal strain.

• A. Silica
• B. Fireclay
• C. Magnesite
• D. Zirconia

Explanation: Fireclay bricks are commonly used to line hot-blast mains because they withstand temperatures around 1000°C and are economical.

• A. 0.5
• B. 1
• C. 2
• D. 3.5

Explanation: Silica bricks undergo a comparatively large irreversible expansion during firing because quartz transforms into higher-volume crystalline…

• A. Fireclay
• B. Very low alumina
• C. Dolomite
• D. Silica

Explanation: Silica refractories have a sharp melting behaviour, so their refractoriness under load lies relatively close to their PCE or fusion…

• A. Permanent linear change
• B. Modulus of rupture
• C. Resistance to CO attack
• D. RUL

Explanation: A dilatometer measures dimensional change during heating and cooling, allowing the permanent linear change of a refractory to be…

• A. Alumina
• B. Thoria
• C. Zirconia
• D. Magnesia

Explanation: Thoria has an exceptionally high melting point of about 3070°C, higher than alumina, zirconia, and magnesia.

• A. Semi-silica
• B. Silica
• C. Bakelite impregnated or fused periclase
• D. Fireclay

Explanation: Slide-gate components face severe abrasion, thermal shock, and molten-steel contact, so they use dense fused periclase or…

• A. None of these
• B. Yellow
• C. Black
• D. Light buff to reddish buff

Explanation: Fireclay bricks commonly range from light buff to reddish buff, with the colour influenced by iron compounds and firing conditions.