Slag Detection System

Continuous thermal mapping to minimise slag carry-over in steel production

The Slag Detection System has been developed using Land’s expert knowledge of the application and over 60 years of experience in the steel industry to monitor and aid control of slag carry-over from one process to another.The Slag Detection System is specially designed to withstand the harsh conditions of continuous operation in the steel plant, with a minimum maintenance requirement. The industrial thermal imaging sensor is housed in a rugged, water-cooled and air purged enclosure, continuously viewing the tapping area. As the tap commences, the dedicated software automatically begins to record the tap as well as producing a data log and graph of the relevant steel/slag data.When the level of slag reaches the pre-determined level and alarm is generated (see above) to stop the tap. The recording will end and the files saved by tap number. Full access of the tapping data is available to the operator for quality control purposes.

Key Features Key Benefits
  • Alarms generated by the system directly stop the tap before the slag is carried over
  • Fully automatic operation
  • Enhanced data output for tap analysis
  • Accurate detection independent of charge weight
  • Reliable alarm independent of the operator
  • Product Traceability – Automatic storage of temperature data from each coil for subsequent analysis
  • Improved production yield
  • Lower slag content – improving steel quality
  • Lower maintenance on BOF/EAF vessel
  • Reduced energy costs


When liquid steel is tapped from a basic oxygen furnace (BOF) orelectric arc furnace (EAF), it is essential to minimise the quantity of slag carried over into the ladle. In the past this has been done by visual inspection of the tapping stream or by the use of electromagnetic induction coils mounted onto the furnace. However, neither of these methods has proved to be entirely reliable.

Main Problems of slag carry-over

  • Slag layer hinders addition of alloys and conditioners
  • High levels FeO and MnO results in high oxygen content of steel leading to increased processing time and treatment costs
  • High inclusion formation, steel cleanliness problems and increased risk of nozzle clogging in the caster
  • Phosphorous reversion in the ladle
  • Poor ladle desulphurisation
  • Ladle refractory wear



Low Temperature (C): 600 High Temperature (C): 2000
Technical Details


Image Processing System
Slag detection: Alarm activation when a preset percentage of either slag or steel detected within defined window
User Display: Front page information display, plant logo and identifier
Frame rate: 30 frames/sec.
Automatic functions: Auto tap detection, steel/slag ratio, video file, log file of all data, steel/slag percentage graph, all saved as tap number
Languages: User defined
Outputs: Digital output card, DDE, OLE, Ethernet and OPC Options

Sensor Supply Unit
Functions: Local connection interface between imaging sensor and image processing system
Ethernet/Fibreoptic Cables: Supplied by the customer

Service: Water, air, power input, communications, video, located to the rear of the enclosure
Added Protection: Sacrificial plate protects the main enclosure from direct impact
Sighting Tube: Design significantly reduces the risk of direct impact of liquid steel against the field replaceable sapphire window
Air bleed: Provides positive pressure within the enclosure
Environmental rating: IP65

Thermal Imaging Sensor
Temperature measurement range: 600 to 2000 °C
Thermal image resolution: 384 x 288 pixels
Detector: Microbolometer, focal plane array
Wavelength: 3.9 µm
Field of View: 7.5° x 5.5°
Motorised focusing range: 4m to infinity

All accuracy specifications:
All accuracy specifications are stated fro 30 °C / 86 °F indicated ambient temperature
% specifications are “% of reading” and appply to measurements in both °C and °F

Download Datasheet
Slag Detection

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