International Symposium on Uranium Raw Material for the Nuclear Fuel Cycle: Exploration, Mining, Production, Supply and Demand, Economics and Environmental Issues - IAEA CN-216

Advancements in exploration and In-Situ Recovery of sedimentary-hosted uranium

25 Jun 2014, 15:00

30m

VIC (Vienna)

Oral Uranium production based on in situ leaching (ISL) Uranium production based on in situ leaching

Speaker

Dr Peter H. Woods (IAEA)

Description

This paper describes recent advancements in exploration technologies for sedimentary-hosted uranium deposits as basis for improved model-based planning and optimization of in-situ re-covery (ISR). High-resolution shallow (<500m depth) seismic in combination with refraction tomography is used for high-fidelity imaging of true-depth stratigraphy of sedimentary formations, tectonic faults and specific structures for the improved understanding of (hydro)geology in general and as potential indicator for uranium mineralization in particular. A new-generation geophysical downhole-wireline tool with pulsed neutron generator has been developed (i) to accurately measure U grade (PFN [prompt fission neutron] method with im-portant in-tool corrections for systematic influences), (ii) to determine geophysical parameters including porosity, density, macroscopic neutron cross section (clay content) and deduced permeability, and (iii) to log the mineral composition (based on element-specific -ray spec-troscopy applied to natural -rays as well as -rays from inelastic neutron scattering, thermal-neutron capture and neutron activation) – all by one tool. This new data - together with conventional geophysical and geochemical information – pro-vides an excellent aid to the assessment of ISR feasibility, the design of wellfields and plan-ning of wellfield operation. A new kinetic leaching model (reactive transport) has been specifically adjusted to acidic leaching conditions considering kinetic rates of the main neutralizing and redox reactions as function of both pH and oxidation potential (balance of e- acceptor species). It is used as an effective tool for predicting wellfield recovery curves, estimating chemicals’ consumption and optimizing leaching chemistry (i.e. dosage of chemicals to injection lixiviant) in dependence on mineralogical conditions (abundance of main reactants).