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Montero’s bulk leach metallurgical testing returns
94% to 97% Total Rare Earth Element recoveries at Wigu Hill Project
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Toronto, Ontario (April 13 , 2015): Montero Mining and Exploration Ltd. (TSX.V: MON) has received positive results from bulk leach
testwork completed on three samples of REE bearing carbonatite dike material from Montero’s Wigu Hill Project in Tanzania.
Mintek reported that all samples returned very promising leaching efficiencies, with rare earth elements (REE) extraction recoveries
of between 94% and 97% TREE (Total Rare Earth Elements). Initial hydrometallurgical testwork undertaken on similar mineralized
material in 2011 (see news release - 29/11/2011) was successful in identifying a hydro-metallurgical 3-stage leaching process to
extract the REE in solution.
Dr. Tony Harwood, President and Chief Executive Officer of Montero commented; “Recently performed bulk leach
metallurgical testwork returned excellent results with high leach efficiencies achieving recoveries of 94% to 97% TREE
reported from REE bearing carbonatite dikes from Wigu Hill. Montero continues to seek a partner to advance Wigu
Hill to a mining stage, similar to our phosphate project, which is funded to pre-feasibility and bankable feasibility
study stage. ”
Montero has completed a series of mineral processing and hydrometallurgical testwork programs. Bulk samples of the bastnaesiterich carbonatite were used by Mintek and SGS Laboratories for mineralogical analysis, mineral processing and hydrometallurgical
testwork. Mineral processing testwork included x-ray sorting (see news release 01/02/2012) and froth flotation (see news release
29/7/2013) aiming to produce a high grade REE mineral concentrate. The principle focus for all test work programs is to develop an
economic process to deliver saleable REE products and as such the hydrometallurgical testwork at Mintek has been successful in
achieving this result.
Mintek developed a 3-stage hydro-metallurgical leach process and was asked to optimize this process. Additional sample material
was sent to Mintek for this purpose and assaying of the bulk sample returned a value of 11.01% TREE.
The optimized results from Mintek on three samples concluded:
“ The first stage is a gangue acid leach to reduce the carbonate content, which successfully reported approximately 55% mass loss for
all the gangue leach tests done, but with minimal rare earth losses. The second stage (caustic crack stage) was successful in the
removal of 71% of the silica in the samples, and the precipitation of the rare earths as hydroxides with minimal TREE losses. The third
and final stage (a reductive acid leach stage) established that 94% to 97% of the TREE’s can be recovered into the leach solution and
from this, precipitation to provide a Mixed Rare Earth Oxide (MREO) concentrate for refining. ”
The final phase of the hydrometallurgical teswork is solvent and ion exchange to prepare individual purified REE products. Mintek
has developed a rare earth solvent extraction pilot plant for this purpose and Montero has delivered a 1.5 tonne bulk sample to
Mintek to further define the final stage REE extraction processing.
Montero’s focus has been to establish the most efficient and economic mining and metallurgical extraction process in order to
achieve margin and cash flow from the high grade REE mineralization at Wigu Hill. The fresh rock nature of the mineralization allows
the use of conventional mineral concentration methods, which are showing successful results.
Drilling at Wigu Hill has delivered a NI43-101 compliant Inferred Resource Estimate (see news releases - 12/09/2011 & 06/08/2013)
on the Twiga and Tembo Zones on the far-east flank and identified a number of mineralized zones across the full extent of Hill. Grab
sampling, trench sampling and selected drilling has highlighted the more centrally located Nyati zone as having significant upside
mineral potential, which needs to be substantiated by further infill drilling to expand the resource potential. Drill testing of this, and
other known mineralized zones at Wigu Hill is still required. .
Qualified Person’s Statement
The technical information contained in this press release has been reviewed by Mr. Mike Evans, M.Sc. Pr.Sci.Nat., who is a qualified
person for the purpose of National Instrument 43-101 and a consulting geologist to Montero.
About Mintek
Mintek, South Africa's national mineral research organization has over 25 year experience in REE extraction and is one of the world's
leading technology organizations specializing in mineral processing, extractive metallurgy and related areas. Working closely with
industry and R&D institutions and reporting to the South African government's Minister of Mineral Resources, Mintek offers a
complete range of process development services, from preliminary bench-scale investigations to large-scale piloting and integrated
flow sheet development in support of bankable feasibility studies. Engineering design, plant construction and commissioning are
carried out in conjunction with international partners. Comprehensive laboratory and piloting facilities for sample preparation,
milling, flotation, physical separation, smelting, leaching, pressure leaching, and metal recovery and purification are supported by
internationally accredited analytical laboratory and mineralogical services. For further information on Mintek, please visit
www.mintek.co.za.
About Montero Mining & Exploration
Montero Mining and Exploration Ltd. is a mineral exploration and development company focused on bringing in a strategic
investor or joint venture partner for the further development of the Wigu Hill Rare Earth Element Project in Tanzania. Montero’s
phosphate projects in South Africa are funded to pre-feasibility and bankable feasibility study stage by a strategic investor. The
phosphate studies are for an integrated rock phosphate mine and fertilizer operation. Montero trades on the TSX Venture
Exchange under the symbol MON.
Signed. Dr. Tony Harwood - President and CEO
For more information, contact:
Montero Mining and Exploration Ltd.
Tel: +1 416 840 9197|Fax: +1 866 688 4671
E-mail:ir@monteromining.com
www.monteromining.com
CAUTIONARY STATEMENT: Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange)
accepts responsibility for the adequacy or accuracy of this release. This News Release includes certain "forward-looking statements, which often, but not always, can
be identified by the use of words such as "believes", "anticipates", "expects", "estimates", "may", "could", "would", "will", or "plan" . These statements are based on
information currently available to Montero and Montero provides no assurance that actual results will meet management's expectations. Forward-looking statements
include estimates and statements with respect to Montero’s future plans, objectives or goals, to the effect that Montero or management expects a stated condition or
result to occur, including Montero’s estimates with respect to mineral resource quantities, grades and economic potential. Since forward-looking statements are based
on assumptions and address future events and conditions, by their very nature they involve inherent risks and uncertainties. Actual results relating to, among other
things, results of exploration, project development, reclamation and capital costs of Montero’s mineral properties, and Montero’s financial condition and prospects,
could differ materially from those currently anticipated in such statements for many reasons such as: the ability to negotiate an investment with a strategic investor on
acceptable terms; changes in general economic conditions and conditions in the financial markets; changes in demand and prices for minerals; litigation, legislative,
environmental and other judicial, regulatory, political and competitive developments; technological and operational difficulties encountered in connection with
Montero’s activities; the ability to complete a feasibility study which recommends a production decision; delays in the development of projects; capital and operating
costs vary significantly from estimates; and other matters discussed in this News Release and in filings made with securities regulators. This list is not exhaustive of the
factors that may affect any of Montero’s forward-looking statements. These and other factors should be considered carefully and readers should not place undue
reliance on Montero’s forward-looking statements. Montero does not undertake to update any forward-looking statement that may be made from time to time by
Montero or on its behalf, except in accordance with applicable securities laws.