Thermal neutron prompt gamma activation analysis (PGNAA) has proven to be a useful tool for the multi-elemental characterization
of coal. The use of isotopic neutron sources allows the construction of relatively small irradiation facilities for the on-line
analysis of large volume samples. As a first step to an on-line analysis system for process control in a coal blending plant
we have developed a facility using a Cf-252 neutron source with an actual strength of 1 mg. This source, which is shielded
by layers of high purity lead and paraffin, can be moved to the center of cylindrical sample holders containing up to 150
kg of coal. To avoid background radiation the sample holders are made from polyethylene. The prompt gamma rays emitted from
the sample are measured with a 22% high purity germanium detector housed in a special horizontally extended cryostate assembly.
The detector is positioned on top of the sample; it is surrounded by a multi-layer decreasing Z-absorber to reduce low energy
gamma background. Paraffin loaded with 95% enriched lithium-6-carbonate is used between sample and detector as a gamma window
with high absorption for thermal neutrons. Moreover the detector is shielded against background radiation by lead and natural
lithiumcarbonate. The data processing system consists of high count-rate analogue electronics including pileup-suppression
and a fast data acquisition system, which permits on-line analysis of the collected data. Analysis of several samples of simulated
coals as well as Western Germany coals shows a good spectral response of our system for the elements H, C, Al, Si, S, Cl,
Ca, Ti and Fe, whereas the sensitivity for N, K and Na is somewhat lower. This means, that the quantitative determination
of the above elements will be possible within 20 minutes. Optimization of the system is continued with a stress on analysis
time and detection sensitivity.
The conductivities of binary mixtures of glycerine and water were measured at 20C by means of a transient method. The equation
describing the correlation between concentration and thermal conductivity was determined. The equation can be used for determining
concentrations in mixtures. The results show that (1) the error in the determination of the molar concentration of water in
mixtures is less than 1%, (2) the time of measurement is 1 s, (3) this method can be used for on-line analysis in production
Coal and mineral processing operations can be controlled more economically if information on process variables is obtained continuously. Much of this information can be provided by nuclear techniques. Recent Australian developments in on-line nuclear gauges are reviewed. Techniques have been developed, field tested and commercialised for the on-line analysis of ash and moisture in coal and for the in-stream determination of solids weight fraction and ash in coal slurries. Techniques are being developed for the on-line analysis of moisture in coke and sulphur in lead sinter feed. As well, techniques are being developed for the bulk analysis of silver, lead and zinc in drill cores.
XRFS can be successfully used for routine on-line analysis of different agricultural products, for instance where food quality control is necessary. The optimization of the system for such purposes and the results obtained are shown on the example of the analysis of coffee.
Authors:J. Chen, E. Hildebrandt, H. Delaney, W. Boivin, E. Bialas, E. Bialas, E. Attas and M. Heinrich
Automated alpha and gamma spectrometry systems have been fabricated to analyze large numbers of samples in batches and to perform on-line analysis for a number of experiments concurrently. Specially designed sample changers for alpha and gamma spectrometry and gamma scanners for used fuel and in-situ glass leach experiments have been built. These communicate through digital interfaces, microprocessors, microcomputers and programmable controllers to a Nuclear Data model ND6700 computer/spectrometer. Application software for data entry and reports has been written to interact with Nuclear Data software to pemit easy and efficient operation.
There is an increasing need in industry, arising from both economic and environmental considerations, to reduce costs and improve product quality through the use of automation. The use of on-line analysis instrumentation provides plant operators with a means for continuous measurement and rapid response. This can result in better control of process efficiency, product quality and resource utilization, all of which produce significant economic and environmental benefits. On-line measurement of bulk elemental composition is important in many industrial applications and is best achieved with highly penetrating neutron-gamma techniques. This paper presents recent work by CSIRO Minerals on the development and implementation of such a technique, NITA (neutron inelastic-scattering and thermal-capture analysis). NITA is distinct from the more common PGNAA (prompt neutron gamma activation analysis) technique in its use of fast neutron sources to generate inelastic scattering reactions, and in its consequent ability to excite gamma-rays from industrially important elements such as carbon and oxygen. The paper will compare the features of NITA and PGNAA analysers and will discuss applications of NITA in industry, including the on-line analysis of composition in pyrometallurgical applications and the on-conveyor belt monitoring of cement raw meal and coal.
Authors:N. Batalha, L. Pinard, S. Morisset, J. L. Lemberton, Y. Pouilloux, M. Guisnet, F. Lemos and F. R. Ribeiro
under the following conditions: temperature 220 °C; total pressure 30 bar; H 2 / n -C 16 molar ratio 20; and weight hourly space velocity (WHSV) between 2 and 100 h −1 . To avoid on-lineanalysis problems, n -hexadecane was diluted in 90 mol% n