Acid baking looks to be an efficient option to process Eco Ridge

first_imgProcessing design improvements have resulted in sharply higher recoveries of critical rare earth oxides (REO), including neodymium, dysprosium and yttrium oxides, at Pele Mountain Resources’ Eco Ridge mine rare earths and uranium project in Elliot Lake, Ontario. The company says “the design improvements present opportunities to improve upon the robust PEA and will result in a significantly greater emphasis on REO production than was envisioned previously.” The company is rapidly advancing work to realise these opportunities and together with its technical team has reached the following decisions:The processing flowchart will be modified to optimise REO recovery and will include acid baking rather than the heap leach and bioleach methods proposed in the PEA. Acid baking is a well-established process for extracting REO from monazite, the primary REO-bearing mineral at Eco Ridge, and is expected to improve mineral recoveries by up to 10-fold for Light REO such as neodymium oxide and by up to more than double for heavy REO such as dysprosium and yttrium oxidesThe modified processing flow chart will also include crushing, grinding, and ore concentration using magnetic separation and flotation prior to acid-baking. Bench-scale testing has demonstrated that more than 90% of total REO can be concentrated into just 20% of the initial ore massThe mining width at Eco Ridge may increase modestly beyond the average 2.7 m used in the PEA, by including material from the Hanging Wall, in addition to the Main Conglomerate Bed (MCB). The additional mineralisation recently discovered in the Hanging Wall is expected to add considerable resources and will allow for scalability in production rates in the futureAn updated PEA, incorporating these modifications, is expected during Q1 2012Given the success in optimising the processing flow chart and the excellent recoveries established in the bench-scale tests to-date, Pele is preparing to conduct larger scale bench testing and pilot plant operations during the first half of 2012.Metallurgical testing at SGS Canada and the Saskatchewan Research Council (SRC) using acid baking, has demonstrated greatly improved REO recoveries over those projected in the PEA. Preliminary bench-scale test results show that the acid baking-leaching process is effective for treating Eco Ridge samples with recoveries ranging from over 80% to over 90% recovery of total REO. This compares to recoveries used in the PEA, which relied on heap leach and bioleach methods, and averaged 7% for Light REO, 34% for Heavy REO, and 70% for U3O8.SRC is also working to optimise the physical concentration of Eco Ridge ore to reduce the total mass requiring treatment in the acid baking process. Bench-scale crushing and grinding tests have resulted in 75% of the crushed ore reporting to the coarse fraction (particle size 45-300 micron) and the other 25% reporting to the fine fraction (particle size <45 micron). The coarse fraction is readily concentrated with magnetic separation, a simple and low-cost technique, with preliminary results demonstrating 97% REO recovery from just 18% of its initial mass. The fine fraction is also readily concentrated, through flotation, with preliminary results demonstrating 77% REO recovery from just 24% of its initial mass. Combined, these results indicate that the two methods can achieve at least 90% REO recovery from just 20% of the initial mass. The ability to physically concentrate the ore will reduce acid baking costs substantially.last_img

Posts Tagged with…

Write a Comment

Your email address will not be published. Required fields are marked *