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kiln Refractories Selection Criteria

Zoning in cement kiln

• Drying Zone / Chain Zone
• Preheating Zone / Calcining Zone
• Safety Zone
• Upper and Lower Transition Zone
• Sintering (Burning) Zone
• Cooling Zone

Drying Zone / Chain Zone

• High abrasion/wear caused by the movement of the chains
• Low material temperature
  (100-400 °C)
• Selection of Bricks:

Dense fire-clay

Air setting mortar (water resistant)

Dense, fire-clay castables (if chain hangers requires extensive modification work)

Preheating Zone / Calcining Zone

• Preheating Zone: Driven off hydrate-water and heating up of raw material:
  up to 700°C.
• Calcining Zone: Starts below 600°C and ends at approx. 1200°C. Most part takes place at 700-900°C
• Mechanical abrasion by material, temperature changes

• Selection of Bricks:

  Preheating Zone

Low alumina fire-clay

Lightweight fire-clay (better thermal insulation)

Calcining Zone

Normal fire-clay

Lightweight fire-clay

Acidic light weight bricks (SiO2 : > 65%) in case of alkali attack

Safety Zone

• High temperature variations
• Chemical attack (eutectic reactions)
• Alkali attack
• Selection of Bricks:

Low porosity (<16%)

High thermal shock resistance

Basic bricks

Alumina rich bricks:
Al2O3: 50 to 60%

Transition Zones

• Highest thermal load
• No or only unstable coating
• Directly exposed to the flame radiation
• High temperature variations (flame and secondary air)
• Attack by alkali salts and clinker melts
• Selection of Bricks:

Magnesia-spinel bricks of very pure (synthetic) materials (chrome free)

Sintering (Burning) Zone

• Material temperature: 1100 °C to 1400 °C (up to 1500 °C)
• More or less stable coating, formed with clinker and liquid phase.
• Attack by increased material diffusion with formation of the C3S
• Attack alkali salts
• High temperatures (overheating)
• High thermal shocks depending on coating stability

• Brick Selection

Dolomite

Chrome-free magnesia-spinel

Hands off magnesia-chrome bricks

Cooling Zone

• High thermal shocks (secondary air temperature, clinker/coating)
• Abrasion (clinker dust)
• Alkali attack
• Overheating
• Brick Selection

Dense, abrasion resistant high alumina bricks Al2O3 80 %
(with SiC)

Basic bricks (Mg-spinel) in case of heavy chemical attack.

if you have any Questions , please don’t Hesitate to consult our Refractories consult Department at project20062015@gmail.com