From GoviEx's NI 43-101 Updated Integrated Development Plan for...

From GoviEx's NI 43-101 Updated Integrated Development Plan for the Madaouela Project:


13.7.4 Ablation

Ablation works by combining the ore with water to form slurry and impacting the slurries together to form a high energy impact zone that separates heavier uranium minerals from the host rock, resulting in a reduced throughput requirement (Figure 13-8) on the downstream leaching circuit.

Figure 13-8: Typical ablation process flow diagram (source: Ablation Technologies)

Uranium is recovered from two streams, soluble uranium is recovered through dewatering and this is fed to the solvent extraction and is also recovered from the leach circuit in the mill within the sulfuric acid stream.

Two tests were conducted using different slurry total suspended solids concentrations, slurry velocities, and ablation time. Table 13-7 details the elemental deportment by PSD, the small scale tests initially indicated that 84% of the uranium can be isolated in the fines fraction (<149μm) and contained within the slurry. The recovery of uranium in a large scale pilot and the full scale plant will be significantly greater as the throughput and velocities increase the energy in the high impact zone resulting in greater ablation of the cemented particles, furtherfurther teswork has shown the recovery to be in the order of 99%. 72% of the molybdenum contained within the ore also reports to the fines fraction (<149μm). The amount of material requiring to be leached is reduced by 64%.

Table 13-7: Initial testwork - Post ablation particle size elemental deportment

Figure 13-9: Initial Testwork - Pre and Post ablation elemental deportment

Figure 13-9 indicates the increased concentration of elements in the fine fractions (in particular <400 Mesh, equivalent to <37μm) and the overall increase of particle mass to the finer end of the PSD due to the ablation process. Further testwork is required to establish the optimum particle size cut off and process parameters. Commercial scale units with higher pump velocities and throughput capacities are likely to result in improved PSD elemental deportment and hence uranium/molybdenum concentrations. Initial methods have already been tested by Ablation that show improved uranium recovery.

One 20 kg sample was run in late 2013 through the Wyoming pilot plant with SRK present, sub-splits were taken for analysis in the UK. Chemical analysis was by XRF and calcite mass by XRD. Table 1 details the elemental deportment by PSD, the small scale tests to date show that 90% of the uranium can be isolated in the fines fraction (<149μm) and contained within the slurry. Approximately 69% of the molybdenum is returned in the same material along with 33% of the calcite present. Approximately 39% mass of the total sample is recovered for the leaching circuit. Results show a slight decrease in molybdenum and calcite recovered and an increase in uranium and the mass recovered.

The current costs although conservative will be maintained as it is considered we have insufficient data for any refinement. However, due to the recirculation in the system and greater pressure from the nozzles the separation of uranium from carbonates has been improved.

Table 13-8: Results of 20 kg Ablation test, Wyoming

Recycle of the residue through a second ablation circuit gave the same results for uranium and molybdenum recovery although no appreciable further calcite was rejected (Table 13-9).

Table 13-9: Results of Second Cycle Ablation test on +200 μm fraction

Thus overall 99% of uranium and 90% of molybdenum is recovered to the leach feed material along with 50% of the calcite gangue. Consequently the gangue acid consumption has been reduced with calcite concentration in the leach material reduced to the equivalence of 13 kg H2SO4/t assuming one mole of acid is consumed by one mole of calcite in addition to the acid requirement for uranium leaching.