• Andrew Halverson

Effective Reduction of the Toxicity of Uranium Mine Waste Piles through HPSA Remediation

Disa’s High-Pressure Slurry Ablation (HPSA) technology is uniquely suited to reclaiming uraium waste piles due to its revolutionary ability to liberate material along its intergranular boundary lines. During particle-to-particle collisions in the HPSA collision chamber, natural uranium bearing minerals such as carnotite which exhibit quartz association are selectively fractured and liberated from the quartz grains. This selective fracture allows the natural uranium bearing minerals and other constituents of concern to be separated based on size downstream from the HPSA processing unit. In uranium waste pile reclamation applications, the HPSA process concentrates the uranium and other heavy metal contaminants into this significantly smaller portion of the waste pile mass, reducing transportation costs for disposal by greater than 70%. In full scale applications, Disa can arrive with its mobile process, concentrate the uranium contaminants for disposal and leave a clean coarse fraction of material on site, which is stable and poses no further hazard.


HPSA has repeatedly demonstrated that it can concentrate greater than 80% of the uranium and vanadium in the processed material in less than 20% of the total processed mass and in some cases can concentrate over 90% of the uranium contaminants into less than 15% of the total processed mass. Further, Disa has proven with testing on a uranium waste rock pile in western Colorado, that HPSA effectively reduces the overall toxicity of reclaimed material for every constituent of concern. As demonstrated in Table 1 by analysis of natural uranium and thorium radioactive decay products, the HPSA can effectively reduce the activity concentrations of all hazardous radioactive material in the waste piles by greater than 43%.


Table 1. Analysis of HPSA Feed and Clean Coarse Fraction for Nat-U and Nat-Th Daughter Product Activity Concentrations


The leachability of hazardous heavy metals and radioactive decay products was analyzed by Toxic Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP). As demonstrated by the results summarized in Table 2, the HPSA clean coarse fraction does not exhibit the characteristic of toxicity according to the Resource Conservation and Recovery Act (RCRA). Furthermore, HPSA not only reduces the concentrations of the radioactive decay products of the natural uranium but reduces the leachability of these decay products as seen in Table 3 indicating overall reduction in the hazards posed by the waste rock material to surrounding groundwater.


Table 2. Results of TCLP Performed on HPSA Fed Material and Post-HPSA Clean Coarse Fraction for RCRA Metals


Table 3. Results of SPLP Performed on HPSA Fed Material and Post-HPSA Clean Coarse Fraction


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