Free Chemical Process Principles MCQs with Answers

• A. Chemical composition
• B. Physical structure
• C. Presence of impurities like iron & alkali
• D. All A., B. and C.

Explanation: Refractoriness under load depends on composition, microstructure, and fluxing impurities such as iron and alkalis.

• A. Crystalline form of MgO
• B. MgCO3
• C. ZrSO4
• D. Amorphous magnesite

Explanation: Periclase is the crystalline magnesium oxide phase, MgO, produced from magnesite after removal of carbon dioxide.

• A. Aluminium phosphate
• B. Water
• C. Lime
• D. Plaster of Paris

Explanation: Water mainly acts as the mixing or wetting medium and is not, by itself, a refractory binding material.

• A. Roof lining of basic open hearth & other basic furnaces
• B. Reheating furnaces
• C. All A., B. and C.
• D. Soaking pits

Explanation: Magnesite-chrome bricks resist basic slags and high-temperature attack, making them suitable for basic furnace roofs, reheating furnaces…

• A. Volume
• B. Neither A. nor B.
• C. Both A. & B.
• D. Specific gravity

Explanation: Conversion of silica to cristobalite involves a lower-density crystal structure, so the specific gravity decreases while the volume…

• A. Decrease in crushing strength
• B. Vitrification
• C. Removal of water of hydration
• D. Development of stable mineral form

Explanation: Firing removes hydration water, promotes vitrification, and develops stable mineral phases; it normally increases rather than decreases…

• A. Reduce its shrinkage on heating
• B. All A., B. and C.
• C. Enhance the strength of fired refractories
• D. Impart greater spalling resistance

Explanation: Grog is already-fired, crushed fireclay, so it reduces shrinkage during reheating and improves resistance to thermal shock or spalling.

• A. Blast furnace hearth
• B. Electric furnaces
• C. Highly chemical resistant equipments
• D. Combustion chamber of blast furnace stoves

Explanation: Carbon bricks are used in electric furnaces, chemically resistant equipment, and blast-furnace hearths because of their thermal and…

• A. 10
• B. 100
• C. 500
• D. 1000

Explanation: Dry mixtures of refractory materials are compacted by high-pressure machine moulding, typically of the order of 1000 kg/cm².

• A. Powdered naphthalene
• B. All A., B. and C.
• C. Calcium phosphate
• D. Ammonium chloride/sulphate

Explanation: Porosity is created when pore-forming additives decompose, volatilise or burn out during firing.

• A. Electrical conductivity
• B. Spalling resistance
• C. Softening temperature
• D. Resistance to slag attack

Explanation: Seger cones bend or deform at characteristic temperatures, so they indicate the softening or refractoriness temperature of refractory…

• A. Increased by the addition of basic oxides
• B. Always more than 2500°C
• C. Not affected by the addition of basic oxides
• D. Reduced by the addition of basic oxides

Explanation: Basic oxides react with an acidic refractory and commonly form lower-melting eutectic mixtures, reducing its fusion temperature.

• A. Fusion point
• B. Spalling rate
• C. Shrinkage ability
• D. None of these

Explanation: An ideal refractory must withstand very high temperatures without melting, so a high fusion point is essential.

• A. Wetting characteristics
• B. Both B. and C.
• C. Thermal conductivity
• D. Refractoriness

Explanation: Carbon refractories combine high refractoriness with high thermal conductivity, allowing them to tolerate severe temperatures and transfer…

• A. Does not react with basic slags
• B. Has poor electrical conductivity at high temperature
• C. Cannot be used as an insulator
• D. Is produced from baddeleyite

Explanation: Baddeleyite is the natural mineral form of zirconia, or ZrO₂, and is used as its raw material.

• A. Should be used in neutral or reducing atmosphere
• B. Exhibit wetting characteristics
• C. Exhibit high shrinkage on thermal treatment
• D. Are not resistant to corrosion by slag

Explanation: Carbon and graphite oxidise readily in air at high temperature, so they are used in neutral or reducing atmospheres.

• A. Segar cones
• B. Pressure vessels
• C. Orton cones
• D. Ovens & retorts

Explanation: Pressure vessels are constructed from structural materials such as steel and are not lined or formed entirely as refractory products.

• A. Side walls of soaking pits and arc furnaces
• B. Copper melting furnaces & converters
• C. All A., B. and C.
• D. Burner block of glass tanks

Explanation: Chrome-magnesite bricks resist basic slags and high temperatures, making them suitable for soaking-pit and arc-furnace sidewalls, copper…

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

Explanation: Silica bricks withstand the high temperature and acidic conditions in the roof of a basic open-hearth furnace.

• A. Silica bricks
• B. Fireclay bricks
• C. High alumina bricks
• D. Tar dolomite bricks

Explanation: Silica bricks have closely matching values of refractoriness under load (RUL) and pyrometric cone equivalent (PCE) because their…