Nondestructive, Bulk Rare Earth Element Measurement System for Coal

Detection and concentration measurement of rare earth elements (REE) in a sample allows REEs reclaim processes to be used cost-effectively by only processing coal containing a sufficiently high concentration of REEs. Adelphi Technology proposes to develop a field deployed commercial prototype instrument capable of non-destructively determining the elemental composition of nearly any sample using neutron activation analysis (NAA). Neutron activation analysis (NAA) of a petri-dish sized sample using a neutron generator and an HPGe detector will be performed on test samples that are representative of real- world samples, but contain known quantities of REEs. The detection limits for each REE will be determined as a function of neutron flux and sample measurement time for both prompt and delayed NAA under fast and thermal neutron irradiation. Prompt and delayed NAA measurements will be performed on known masses of REEs to determine the expected signals from each REE for this system. Known masses of REEs will be added to samples that are representative of coal or coalmine sludge, representing 0.001, 0.01, 0.1, 1, 10 and 100 ppm concentrations of REEs. The detection limit for each sample as a function of detection time and neutron flux will be determined using a combination of thermal and fast neutrons and both prompt and delayed NAA. The optimum measurement protocol will be determined, for example, for a 2 minute measurement the protocol may be: fast irradiation: a)25 secs prompt measurement/generator on, b) 25 secs delayed measurement/generator off, followed by thermal irradiation: c) 25 secs prompt measurement/generator on, d) 25 seconds delayed measurement/generator off. The outstanding 20 seconds would be for loading and removing the sample and moving it between irradiation ports, which ultimately would be performed by a mechanism inside the instrument. This research will feed in to moderator and system integration design to produce a portable instrument capable of measuring the concentration of practically all of the elements in a sample. This experimental investigation will provide experimental evidence of achievable detection limits in a practical real-world system using samples that are representative of typical samples from a mine or burnt-coal processing facility. This has applications beyond REE recovery from coal, and would additionally assist Adelphi in selling neutron generator based instruments to precious-metal mining companies and potentially belt-analyzer companies.