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Rare Element Makes Significant Progress with Rare-Earths MetallurgicalTesting

^{Published on 2009-09-29 10:15:29 - Market Wire}
 

 1. With vigorous attrition scrubbing, a recovery potential of 90% was achieved in 32 wt-% of the original sample weight while still retaining a grade of 13% rare-earth oxide (REO); the REO resides in the finest fraction (minus 500-mesh) pre-concentrate. 2. Further upgrading of the minus 500-mesh (25(micro)) pre-concentrate by flotation may be able to achieve concentrate grades of 40-50% REO. 3. Hydrochloric acid leaching in an agitation leach system is predicted to recover up to about 85% of the total REO from the original mineralized material. 4. Additional testing is likely to provide further improvements to the processing methods. 

 Summary In general, the MSRDI tests have shown that the following conclusions apply: 1. The oxidized REE-mineralized material should be initially crushed to minus 1/4". 2. Beneficiation is best accomplished by scrubbing the material with vigorous agitation for an extended period of time. 3. Screened or cycloned minus 500-mesh particles contain up to 90% of the REE values. 4. Sulfuric acid leaching would require extended times and/or the use of an acid roasting circuit to be viable. 5. Concentrated hydrochloric acid leaching at room temperature is preferable to sulfuric acid leaching; it removes the rare-earth oxides within 6 to 24 hours and recovers up to 98% of the values from the treated minus 500-mesh pre-concentrate. 6. Economic evaluations can be made on acid consumption versus weight percent rejection of the gangue based on value of the discarded rare earth oxide content. 7. Heavy media separation recovers some of the larger particles but is minimally efficient and probably not cost effective. 8. Flotation of original oxide mineralized material can recover a substantial amount of the REE values, but the flowsheet would be complicated with recirculation and stages of cleaning; final concentrate grade may approach that of other plants but the recovery may suffer. 9. Flotation of the minus 500-mesh REE-bearing pre-concentrate has the potential for higher concentrate grades with good recovery and removal of more of the acid-consuming gangue minerals. 

 1. Scrubbing enriches the minus 500-mesh fraction in REE. 2. Gentle scrubbing produces a higher grade but with reduced recovery. 3. Vigorous agitation results in higher REE recoveries but increases the gangue presence. 4. There is less than one percent difference in pre-concentrate REO grade among the techniques. 5. A projected line connecting the two flotation machine tests shows the estimated weight and recovery at points between 10 and 60 minutes.