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MEI Online: Commodities: Metallic Ores: Rare Earths & Thorium: Latest News: February 10th 2015


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:: Search Minerals Announces Successful Scale Up of Proprietary Metallurgical Process to Produce 98.9% Purity Rare Earth Oxide Product


Search Minerals Inc. and its wholly-owned subsidiary, Alterra Resources Inc., are pleased to announce the completion of a scale up test of the Search Minerals Direct Extraction Process on Foxtrot resource to produce a high grade REE product for refining. The scale up test was performed at SGS Minerals, Canada ("SGS") with funding support provided by the Research & Development Corporation ("RDC") of Newfoundland and Labrador and from the Atlantic Canada Opportunities Agency ("ACOA").

Highlights of the process:

  • A channel sample of Foxtrot resource was crushed to 6 mesh (~3.45 mm) size and treated in a scaled up test of Search's Metallurgical Process for rare earth recovery (Jul 23, 2014 Search Minerals Announces Metallurgical Breakthrough for Rare Earth Recovery)
  • The channel sample contained 1.12% Total Rare Earth Oxide (TREO) including 0.183% Nd2O3, 0.0262% Dy2O3, and 0.151% Y2O3.
  • The crushed 6 mesh material was mixed with 100 kg/t of H2SO4 in a rotary contactor and then passed continuously through a pilot plant kiln for heating to 200 C. The acid/ore mixture was easily handled and did not stick on the kiln internals. The material appeared as a dry sand product at the kiln discharge
  • The kiln product was water leached at 10% solids and 90 C for 24 hours to extract the rare earth elements into solution.
  • The leach slurry was filtered to recover the leachate solution and produce a washed solid residue (waste product from the process).
  • The leachate was purified through simple pH adjustment with magnesium carbonate (MgCO3) to reject key impurities (Fe, Al, Si, Th, U).
  • The rare earth elements were recovered from the purified solution by addition of sodium carbonate (Na2CO3).
  • The (unoptimized) recovery of the rare earths to the carbonate precipitate were:
    • 71% N
    • 68% D
    • 64% Y
    • An average recovery of 65% TREE/LREE/HREE
  • There is scope for increasing recoveries through optimization of the acid dosage, temperature and time of heating and particle size of the crushed material. Recovery optimization will be undertaken at the demonstration pilot plant stage of development planned for 2015.
  • The rare earth carbonate precipitate was purified using Search's process of acid re-leaching, pH adjustment to reject impurities, rare earth oxalate precipitate and calcination.
  • The final rare earth oxide product (the calcine) analyzed 98.9% TREO+Y and only 2.4 g/t of Th. This calcine would be refined at a rare earth refinery into separate rare earth elements products for sale. The REE analysis of the calcine is listed below:
    • La2O3 - 14.07
    • CeO2 - 38.57
    • Pr6O11 - 4.68
    • Nd2O3 - 17.96
    • Sm2O3 - 2.93
    • Eu2O3 - 0.17
    • Gd2O3 - 2.46
    • Tb4O7 - 0.40
    • Dy2O3 - 2.30
    • Ho2O3 - 0.47
    • Y2O3 - 12.45
    • Er2O3 - 1.22
    • Tm2O3 - 0.18
    • Yb2O3 - 0.80
    • Lu2O3 - 0.10

Jim Clucas, Interim President and CEO states, "These metallurgy results from the Foxtrot resource confirm that the crucial metallurgical process has been successfully simplified. This success is due to the financial support of ACOA and RDC, the technical support of SGS and the leadership and conceptual ideas of Dr. David Dreisinger. The new process is simple and cost effective, it should lead to the lower capital and operating costs necessary to develop our REE resources".

From these results, the Company anticipates engaging an engineering firm to provide Search with a conceptual study, detailing the initial capital costs and operating costs which will be used to update the Preliminary Economic Assessment report. In conjunction with the conceptual study, Search will continue to work with SGS to scope and cost the design and operation of a demonstration pilot plant. This will provide critical design data for feasibility study evaluation of the Foxtrot Project and provide a mixed rare earth product necessary for refineries to test the next stage of separation.




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