PGNAA Online Analyzer Working Principle
Online elemental analysis has been used in the coal, power and cement industries since the mid 1980’s. The technology of choice in modern mining and processing operations is prompt gamma neutron activation analysis (PGNAA). PGNA analysers detect the presence of and measures the quantity of elements in bulk materials as they are transported on a belt conveyor. Real time, continuous data on the elemental composition of the material is sent from the analyser to the plant PLC where it is used for process control.
The adoption of online elemental analysis has been particularly prevalent in the coal, power, and cement industries. It is increasingly being used in the iron ore and steel industries.
On-line elemental analysers are known by many names. These include; on belt elemental analysers, through belt PGNAA elemental analysers, and neutron activation analyzers.
How PGNAA Works
Material on the conveyor is bombarded with neutrons emitted from radioactive isotope Californium-252 (Cf-252). When neutrons collide with an element in the material, gamma rays are emitted with specific energies unique to that element – in effect, creating chemical signature for that element. The greater the amount of an element in the material the greater the number of gamma rays emitted with the corresponding specific energies. By measuring the specific energies of the gamma rays that are emitted and the counts of gamma rays, an accurate analysis of the chemistry of the material is generated in real time.
There has been significant improvements in on-line elemental analysis over the last three decades. A new analyzer on the market is the AllScan® online elemental analyzer.
Online elemental analyzers have many uses including:
- Sorting of coal
- Blending of coal
- Quality control
- Maximizing coal recovery
- Environmental compliance
- Quarry management and stockpile building in cement
- Raw mix blend control in cement
- Optimizing Boiler Efficiency