Rare Element Resources Ltd. (the "Company"), a mineral resources company advancing development of the Bear Lodge Critical Rare Earth Project, located in northeastern Wyoming, announced today that two independent laboratories, Hazen Research and SGS-Lakefield, have confirmed and expanded on the initial bench scale test results reported by ANSTO, Australia.
The tests confirm the success of the Company's proprietary technology to selectively recover rare earth elements (REE) from acid leach solution using oxalic acid, resulting in a bulk total rare earth oxide (TREO) concentrate with a purity level exceeding 90%. The Company has filed for a Provisional U.S. Patent on the technology. SGS-Lakefield is currently undertaking additional test work and has been awarded the contract for pilot plant testing.
Equally significant, the studies determined that with oxalate precipitation, a significant amount of the hydrochloric acid (HCl) left in the REE-depleted barren solution is recoverable by distillation. After the addition of oxalic acid and subsequent 90+% recovery of the REEs at high temperature, the amount of free acid increases. The recycled acid is projected to provide nearly 80% of the total HCl requirements for the plant.
"The purity of the end product of this innovative process will make the Bear Lodge concentrate attractive to a number of potential users," stated Jaye Pickarts, Chief Operating Officer. "While the primary purpose of the large-scale pilot plant tests will be to develop detailed process engineering design criteria for inclusion in the Feasibility Study, we will use the resulting product generated from this test work to initiate discussions and provide samples to potential customers. We believe this will give them the ability to evaluate the quality of our concentrate and determine its compatibility with their needs, whether that be for advanced technology applications or for use in green technologies."
Process Confirmation
The test work performed by Hazen Research and SGS-Lakefield confirms the effectiveness of the proprietary hydrometallurgical process, which:
- Selectively separates REEs from all base metals in solution and upgrades the recovered REEs by roasting oxalate solids in rotary kilns to produce a +90% pure TREO mixed concentrate. The concentrate is more than double the 45% concentrate used as the basis for the evaluation in the Company's Pre-Feasibility Study completed in 2012.
- Distills free HCl from REE-depleted solution, cutting down on fresh acid cost by recycling nearly 80% of the total HCl required for leaching, as well as recycling a large portion of the process water.
- Crystallizes and removes residual solution from the distillation column containing base metals and other impurities. The distillation process will facilitate either safe disposal or potential recovery of valuable metal byproducts from the residual waste stream.
Hazen Research and SGS-Lakefield conducted all bench scale tests on mineral ores from the Bull Hill and Whitetail Ridge deposits. In addition to confirmatory batch tests, SGS-Lakefield in Canada conducted a mini-pilot test campaign under a continuous mode of operations to confirm REE selectivity and detail key parameters necessary for controlling a large-scale oxalate precipitation process. The work was undertaken over a period of six months with oversight and supervision by Dr. Henry Kasaini, Director of Science and Technology for Rare Element Resources.
Additional Pilot Plant Testing
SGS was awarded a $2.5 million contract to undertake additional pilot plant test work that includes the physical upgrading of various REO ores and hydrometallurgical processing of mineral concentrates to produce final bulk TREO concentrates for marketing purposes. The pilot test work will also assist in identifying process improvements. Approximately 27 tons (21.7 tonnes) of oxide and oxide-carbonate ores from both the Bull Hill and Whitetail Ridge deposits will be tested. While the work is expected to contribute to further refinements of the process, the primary goal will be to develop the detail design criteria necessary for inclusion in the Feasibility Study for the project, expected to begin in mid-2013.
Process Overview
After crushing, washing, screening and magnetic separation at the Company's proposed physical upgrade plant, to be located adjacent to the mine, the mineral concentrates will be delivered to the hydromet facility to be constructed on private property, located near an established industrial park in Upton, Wyoming.
The hydrometallurgical process consists of HCl leaching at moderate temperature, selective precipitation of REE with oxalic acid, and calcination of REO at elevated temperature to produce a high-purity, mixed TREO powder, with the accompanying capture of kiln flue gases.
The hydromet process will employ a hot chloride solution to extract the REOs into a pregnant leach solution (PLS). Using closed reactor vessels, the PLS will react with oxalic acid under optimized conditions to facilitate selective precipitation of REEs. Over 90% of REEs will be precipitated from the PLS leaving impurities in solution, including the major base metals. The REE-rich oxalate precipitate will be converted to its oxide form in a calcination process. The mass of REE-oxalates will be reduced by as much as 50% with the remaining calcined powder resulting in bulk TREO concentrate with a purity level exceeding 90%.
The barren leach solution from the oxalate reactor will contain a significant amount of HCl that will then be recovered by distillation and re-constituted through a rectifier as azeotropic hydrochloric acid (20% strength). This acid will then be recycled for use in the leach circuit. High REO recovery (+90%) and the recycling of significant amounts of HCl (~80%) and water (~85%) to the leach circuit are the major benefits of the oxalate process.
Rare Element Resources Ltd. is a publicly traded mineral resource company focused on exploration and development of rare-earth element deposits, specifically those with significant distribution of critical rare earths. The Company is advancing development of the Bear Lodge Project, located in northeast Wyoming. Bear Lodge is a significant mineralized district containing many of the less common, more valuable critical rare earths that are essential for electronics, fiber optics, laser systems for health and defense, as well as many evolving green technologies, like hybrid cars, solar panels and wind turbines. Permitting and feasibility work on the Project is currently underway.
For additional information, please contact Robbin Lee at 720-278-2462 or [email protected].
Source: http://www.rareelementresources.com/