Thermal processing
In mineralprocessing plant, Dewatering by using Tube Presses represents the highest
energy level of mechanical upgrading of minerals. If further upgrading is
required we have to use thermal processing. Thermal processing is normally classified
according to operating temperature.
Thermal low ( 100-200° C)
Used for drying
- evaporating of liquids from solids - drying
Type of
equipment
•
Direct Heat Rotary Dryers
•
Indirect Heat Rotary Dryers
•
Steam Tube Dryers
•
Indirect Heat Screw Dryers (Holo-FliteR)
•
Fluid Bed Dryers
Thermal medium (850 -950°C)
Used for
calcining, clay swelling, limestone burning and foundry sand burn out
Type of
equipment
•
Direct Heat Rotary kilns
•
Indirect Heat Rotary kilns
•
Vertical Kilns
•
Fluid bed Kilns
Thermal high (1300-1400°C)
Used for
pelletizing of iron ore concentrates and petroleum coke calcining
Type of
equipment
•
Direct heat rotary kiln
Thermal processing basics
Thermal
processing is expensive. This means that lowest input in calories/ton is the
key issue. With raising operating temperatures this issue is getting more and more
critical.
Dryers are
normally not insulated but the kilns are refractory lined to protect the mechanical
parts from the high temperatures needed for processing. Also the systems for
heat recovery are getting more and more advanced with higher energy input.
Thermal
processing equipment is always supplied as an integrated system consisting of:
•
Mechanical Dryer or Kiln
•
Feed and product handling equipment
•
Combustion system (burner, fans, fuel system, etc.)
• Off
gas handling equipment
• Dust collection system (wet or dry)
•
Cooling system (optional)
Direct Heat Rotary Dryer
•
Work horse of the mineral industry
•
Wide range of internal designs for effective drying from start to end
•
Special seals for closely controlled atmosphere
•
Effective combustion and low maintenance burners, safe and reliable
•
Diameter <0,6-5 m (2-17 ft), length 5-30 m (7-100 ft). Feed rates from less
than 1 ton to 500 tons per hour
•
Applications in minerals, clay, sand,aggregates, heavy chemicals and
fertilizers.
Indirect Heat Rotary Dryer (rotary Kiln)
•
Controlled environment interior excludes products of combustion
•
Heat transfer by conduction and radiation
•
Pulse-fired burners available
•
Facilitates recovery of off-gases and product vapours
•
Diameter 0,5m - 4,5 m (1.5-14 ft). Length 2.5 m to 30 m (8-96 ft).
•
Applications in hazardous-, ultra fine- and combustible materials. Regenera
tion of active carbon, pyrolysis of waste rubber (car types)
Iron Ore Pelletizing system (Grate – Kiln)
Lime Calcining System
Coke Calcining System
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