Aclara Confirms Successful Completion of Its Process Flowsheet at LAB Scale
ACLARA CONFIRMS SUCCESSFUL COMPLETION OF ITS PROCESS FLOWSHEET AT LAB SCALE
TORONTO, ON, November 09, 2022 – Aclara Resources Inc. (“ Aclara” or the “Company”) (TSX:ARA) is
pleased to announce the successful completion of a laboratory testing phase undertaken to optimize the
metallurgical process and ensure that liquid residues not are generated. This test work forms part of the
development program for the extraction of Rare Earth Elements (“REE”) from Aclara’s ionic clay resource in
the Penco Module (“Project”) located in the Bio Bio Region, in the south of Chile.
This represents an important milestone in the development of the proposed Aclara REE extraction process ,
now known as “Circular Mineral Harvesting”, as it demonstrates a unique process that not only results in
attractive recoveries of REE but also minimizes the associated environmental footprint. The results show that
95% of the fresh water utilized by the process plant is retained within the circuit, that 99% of the main reagent
(ammonium sulphate) is recirculated, and that no liquid residues will be produced thus negating the need for
a tailings facility. In addition, the mining activities do not require the use of explosives nor subsequent crushing
and milling, resulting in a very low carbon footprint operation. The successful completion of this test work
materially de-risks the metallurgical attributes of the Project.
Although further optimization opportunities continue to be evaluated by the Aclara team, this achievement
allows us to:
• Ensure a stable, closed-circuit process
• Validates the results presented in the PEA with further representative samples
• Improve Dy and Tb recoveries
• Move towards a semi-industrial piloting stage
• Generate intellectual property protected by international patents
The goal of Aclara is to produce a High Purity H eavy Rare Earths (“ HREE") concentrate while ensuring a
minimal environmental footprint. The Penco Module will not use explosives, nor will there be crushing nor
milling circuits in the process flowsheet , which will minimize the use of energy and Green House Gas
emissions. In addition, the high percentage of water and reagent recirculation, and the avoidance of the need
for a tailings facility, and the production of a final product which is free of deleterious radioactive elements are
all key attributes of the novel Aclara process. Finally, Aclara aims to reclaim its production site by growing a
native forest on the impacted areas.
Process Flowsheet Introduction
Before delving into the detail of the metallurgical testing program, a brief description of the process named
Circular Mineral Harvesting is presented to provide context to the importance of the overall program. REE
from the Penco mineral deposit are present in two different mineral forms: as REE elements adsorbed onto
the surface of the clays and as REE contained within the mineralized ores, mainly in the form of Monazite.
The extraction process is focused on recovering only the REE associated with the clays, as these are known
to be soluble in certain acidic solutions with a pH of between 3.0 and 4.0. The process of extracting REE from
clays is commonly called “Desorption” or “Leaching”, and typically occurs in mildly acidic solutions specifically
controlled to maximize the recovery of the REE elements yet minimize the complete dissolution of the host
minerals and thereby avoid concentrating unwanted elements. Optimizing the process conditions is key to
maximizing the project economics with regards to operational costs, capital costs, environmental footprint and
the generation of a final clay material that is safe to return to the mining areas for future revegetation.
The following figure (Figure 1) summarizes the integrated process: mine extraction, desorption, impurities
removal and REE carbonation precipitation as final product. It also includes the washing of the processed
clays prior to being returned to the depleted mine areas for native reforestation.
Figure 1 – Circular Mineral Harvesting Process flowsheet schematic
Figure 2 highlights the positive attributes associated with the Aclara Circular Mineral Harvesting.
Figure 2 – Aclara Circular Mineral Harvesting Attributes
Background of the Process Flowsheet
The extraction process developed prior to 2021 by Aclara with the support of the University of Toronto
consisted of a two-step counter-current desorption process using ammonium sulphate as the main lixiviant
followed by a selective precipitation process using ammonium bicarbonate. The pH used in the desorption
process was 4.0. The precipitated solid was subsequently washed to recover any remaining ammonium
sulphate. The results of this program (“Condition A”) were compiled and served as a base case against which
to compare the performance of the future metallurgical programs.
Metallurgical Recovery Validation Programme
For the 2021/22 metallurgical program, the first step was to validate the initial results obtained at the University
of Toronto using the Condition A process conditions, by testing new, representative samples from the entire
Penco deposit and the introduction of a new variant of the lixiviant solution.
Selection of samples
The selection of representative samples for the metallurgical test program was key to ensuring the test results
accurately represent the minable mineral resources . It is also important for subsequent testing and process
improvements. The metallurgical performance of samples from each mine zone and within each zone may be
variable, and such variability plays a part in the selection of samples. To achieve representativeness, the
sample selection program considered, amongst others, parameters such as f eed grade variations,
mineralogy, and physical location. The sample selection process used Cancha© software to both visually and
statistically analyze the block models to select a total of 119 samples that were used for this program.
Figure 3- Typical Cancha model used for sample selection
Preparation and management of scope of laboratory testing
The 2021/22 laboratory test program was performed by SGS Lakefield in Canada. The first stage was to
replicate t he Condition A process conditions using the new ly acquired samples and then introduce two
additional process conditions (Conditions B & C) to determine their effectiveness . Test Condition B builds
upon the known effect of increasing REE recoveries by using a more acidic solution with a pH of 3.0 instead
of 4.0, and introducing a synthetic lixiviant, which emulates the salts generated in the recycling process, while
controlling the dissolution of unwanted elements and impurities. Condition C included the same new lixiviant
solution as used in Condition B, but at a slightly less acidic pH of 4.0.
In all three cases the main reagent used was ammonium sulphate to remain consistent with the reagent
referenced in the environmental permit application. Although the Company withdrew its environmental permit
application in March 2022 and will refile a new application in the second quarter of 2023, the environmental
regulators are familiar with the proposed use of ammonium sulphate as a reagent, so the Company preferred
to continue using this reagent in order to remain consistent with the environmental permit application. Further
upside exists in the future to evaluate the performance of other reagents.
In summary:
• Condition A – Repeat University of Toronto base line testing but on new samples at a pH of 4.0
• Condition B – Carry out desorption at a reduced pH of 3.0, plus the introduction of a synthetic lixiviant
solution designed to emulate the predicted concentrations of recycled salts generated in the closed-
circuit process
• Condition C - Evaluate the impact of the synthetic lixiviant solution used in Condition B but at a pH of
4.0
Analysis of 2021/22 metallurgical results in comparison to the previous programs
The results of the 2021/22 metallurgical program indicate the following:
• Condition A testing on new samples resulted in a validation of recoveries from the initial program at
University of Toronto and therefore confirmed the results presented on the Amended and Restated
NI 43-101 Technical Report – Preliminary Economic Assessment for the Penco Module Project dated
September 15, 2021 (“PEA Technical Report”).
• Condition B test results indicated a marginal increase in recoveries over that of Condition A
• Condition C test results showed a small improvement over condition A but not as much as Condition
B
Figure 4 shows the results of Condition B and Condition C compared to Condition A as included in the
PEA Technical Report:
Figure 4 – Results of REE Extractions Conditions A, B and C
Even though Condition B showed the highest recoveries in terms of NdPr and DyTb, it also resulted in slightly
higher quantities of impurities such as aluminum in the final Mixed HREE concentrate. Condition C showed
stable recoveries for NdPr and Tb whil e notably improving the recoveries of Dy, which is the element that
drives the most value in our product. Currently laboratory test work is being carried out, where the process
conditions will be defined for further demonstration in the pilot plant campaign.
The fact that all recycled salts were used in Condition C has allowed a full understand the parameters needed
to design a water treatment plant that ensures that water is fully recycled with an efficiency of 95%, that the
ammonium sulphate is recycled with 99% efficiency and that no impurities accumulate in the system with th e
risk of saturating the process.
Impurities and Water Management in the Process Flowsheet
An extensive testing program was carried out with BQE Water during 2021 and 2022 to validate water
treatment requirements for the Penco Module flowsheet, with th e objective of maximizing recycling . During
this program a process was identified which allows the recycling of water in a closed circuit to meet the goal
of zero liquid discharge. The validation of performance at a laboratory scale was completed satisfactorily.
Handling of the impurities in the circuit was also successful, resulting in 90% efficiency in the removal of
Manganese (Mn) without major REE losses. Precipitated impurities are mixed with the processed clays ( the
only output of the plant besides the final product) which fully comply with maximum regulat ory levels and
thereby allowing the placement of the washed clays back into the field without the need for further treatment.
Trials with the processed clays are already underway to demonstrate the amenability of revegetation of the
reclaimed site with native species.
Pilot Plant
Semi-industrial Scalability of the Process Flowsheet
Based on the laboratory results which confirm a metallurgical process with zero liquid discharge, the next step
is the execution of a semi-industrial scale pilot test. In that regard, Aclara has begun to build a pilot plant
operation with multiple objectives as described below:
• Validate the closed-circuit flowsheet to produce a High Purity HREE concentrate at a semi-industrial
scale
• Generate processed clays to demonstrate the chemical stability and amenability for revegetation of
the reclaimed site with native species
• Fine-tune the processing parameters for use in the full-scale plant design
• Demonstrate the process flow sheet for use in the Feasibility Study Report
• Generate approximately 50kg of the Mixed REE concentrate for separation trials in support of future
offtake agreements
• Demonstrate the simplicity and environmental sustainability of the process to relevant stakeholders
The Company has acquired an industrial warehouse in Concepcion which will house the pilot plant and has
put in place the purchase orders for all of the major equipment required for the plant. The plant is scheduled
to run continuously for 2 months during the second and third quarter of 2023.
Pilot Plant Design Parameters
• Design throughput is 90 kg/hr. running on a continual 24/7 basis per campaign
• Two campaigns representing 2 of the 5 mining zones covering the initial payback period of the
project
• Each campaign is expected to run for 1 month
• A High Purity Mixed REE concentrate will be produced for each campaign
• Final Report is expected by end Q3 2023 for inclusion into Feasibility Study Report
Figure 5 – Pilot Plant Schematic
IP Rights
The proposed process flowsheet has two patents in place that protect th is innovation. The first has already
been granted in all the countries that were requested: Chile, Brazil, US, and China , and t he second patent
has recently been filed and is pending to be granted.
Figure 6 – Patent that was awarded in Chile, Brazil, USA and China
Qualified Person
The technical information in this press release relating to the processing facility and metallurgical test work
has been reviewed and approved by Stuart Saich, an independent process engineering consultant with 35
years’ relevant experience. Mr. Saich is a Fellow member of the Australian Institute of Mining and Metallurgy
(FAUSIMM) and therefore an independent Qualified Person (QP) as defined by the National Instrument 43 -
101, standards of disclosure for minerals projects. The QP confirms that he visited the project site in October
2022 and has been supported by the Head of Processing for Aclara Resources, Ricardo Sepulveda.
Ricardo Sepulveda is a chemical engineer with 18 years of experience in chemical, hydrometallurgical and
pyrometallurgical processing related to Copper, Lithium, Rare Earths, Molybdenum, Arsenic, Rhenium,
Antimony, among other elements. He has participated as process leader and project manager in PFS, FS
and detailed engineering for projects with world class companies. At Aclara, Ricardo is the head of process
engineering and leads the metallurgical department including all R&D activities.
About Aclara
Aclara is a development-stage rare earth mineral resources company located in Chile. Aclara is initiating the
development of its resources through a project called the Penco Module (the “Penco Module”), which covers
a surface area of approximately 6 00 hectares and which has ionic clays that are rich in rare earth elements.
Aclara is currently focused on the development and on the future construction and operation of the Penco
Module, which will aim to produce a rare earth concentrate through a processing plant that will be fed by clays
from nearby deposits. Aclara’s unique extraction process offers several advantages such as: no blasting,
crushing or milling required ; no tailings dam ; minimal water consumption due to a high level of water
recirculation; amenable leaching with a fertilizer; and no radioactivity.
Forward-Looking Statements
This news release contains “forward -looking information” within the meaning of applicable securities
legislation, which reflects the Company’s current expectations regarding future events, including statements
with regard to the Company’s development program of the extraction of REEs and expectations as to activities
conducted and the outcomes resulting therefrom; expectations as to the optimization of the Project’s process
flowsheet and the Company’s success in realizing such optimization opportunities; ra tes of recovery,
efficiencies, and composition of precipitates pursuant to the Company’s process flowsheet and any
expectations as to results being scaled at a semi-industrial level; construction and operation of the Company’s
pilot plant; expectations as to activities conducted in connection with the Project, timelines for completion and
the success, effect or outcomes resulting therefrom; and the Company’s operational goals in the near term
and long term and the ability to achieve such goals . Forward -looking information is based on a number of
assumptions and is subject to a number of risks and uncertainties, many of which are beyond the Company’s
control. Such risks and uncertainties include, but are not limited to, the factors discussed under “Risk Factors”
in the Company’s annual information form dated as of March 30, 2022 filed on the Company’s SEDAR profile.
Actual results and timing could differ materially from those projected herein. Unless otherwise noted or the
context otherwise indicates, the forward-looking information contained in this news release is provided as of
the date of this news release and the Company does not undertake any obligation to update such forward -
looking information, whether as a result of new information, future events or o therwise, except as expressly
required under applicable securities laws.
For further information, please contact:
Ramon Barua
Chief Executive Officer