Principles of Operation

1. Principles of Operation

2. Prompt Gamma Neutron Activation Analysis, What is it? • Elemental Analysis Technique • Bulk Analysis Method • Penetrating Technology • Non-Destructive Analysis Tool

3. The PGNAA Process • Neutron source 252Cf emits neutrons. • Thermal neutrons are absorbed and cause gamma ray emissions • Each element reacts differently • When the gamma ray strikes the NaI crystal a photon of light is emitted. • Gamma ray detection system converts counts into an energy spectrum • High speed digital electronics and sophisticated software convert the spectra into elemental composition

4. PGNAA Detection Electronics enclosure Detector Assembly A/D Converter Pulse Processor (DSP) PreAmp Detector PMT OpCon Data Processing

5. Counts 0 100 200 300 400 500 600 Channel Typical PGNAA Gamma Ray Spectrum for Coal

6. The measured spectrum S Si Fe C + + + × 1 × 2 × 1 × 0.25 Method of Spectral Analysis

7. Parameters Measured

8. Calibration is critical to good performance • Thermo uses high purity chemicals to calibrate the analyzers in the factory before they are shipped to the field. • This is critical as it insures that there are no correlations between elements in the calibration. • This is not possible to do if calibration is done in the field with coals. • The value of the factory calibration is that the analyzer will perform properly with any mixture of coal seams. • The calibration uses every element normally seen in coal. • With out information on all the elemental data, the result would be less accuracy.

9. How are the analysis calculated? • PGNAA measures the weight (in kg) of the elements of interest in the sample. (S, Si, Al, Fe, Ca, K & Ti) • The elemental weight of the ash oxide elements are converted to the weight of the oxides in the ash. • Eg. Ca + ½ O2→ CaO therefore 1kg Ca = 1.39919kg CaO • The kg are then each divided by the analyzed sample weight to get the % weights. • The percent as received ash is then calculated • AR Ash = (sum of six oxides)/(1 - % other as a percentage of ash) • Other is the sum of SO3 + MgO + Na2O + P2O5 + Undetermined • In situations where the Na2O content is great enough (0.20% of coal), it is used in the ash calculation above.

10. Calibration Ranges * Moisture is determined from Moisture Gauge** Ash is determined from the sum of ash oxides No correlations exist between components

11. Moisture Measurement • Thermo uses microwave moisture gauges to measure the free moisture in the coal. • Total moisture is the sum of the free moisture plus the bound moisture for the coal being analyzed. • Moisture measurements are needed to: • Determine the dry analysis values (PGNAA measures as received) • To calculate the heat content of the coal • To calculate the emissions potential as a function of heat content

12. CV and emission calculations • CV is calculated based on the moisture ash free CV (MAF CV) of the coals being analyzed. • Lbs SO2/million Btu (in USA) • Or any empirical formula the customer uses to measure performance.

13. Information on Coal input by the customer • The following coal parameters need to be input by the customer. • Other Ash oxides • MAF CV • Bound Moisture • COBOS Thermo’s coal blending software package will weight average these values to allow the correct constants to be applied to the analysis results.

14. Analysis differences between PGNAA and Dual-gamma analysis technologies Dual-gamma ash gauge Measures average AtomicNumber PGNAA elemental gauge Measures Elements that make up the ash Detector Cf Source neutrons gamma rays NaI Detector Am & either Ba or Cs Source PGNAA much less affected by composition differences within the cross-sectional profile of coal on the conveyor