This report documents the proposed processing and recovery designs for the Don Mario Property’s oxide stockpiles and tailings, along with supporting metallurgical testwork and historical operating data.
Report context
The Don Mario Property, located in the San Juan Canton, Chiquitos Province, Santa Cruz Department, eastern Bolivia, is covered by this National Instrument 43-101 Technical Report with an effective date of 28 February 2022. The report was prepared for Empresa Minera Paititi, S.A. and describes mineral processing and metallurgical testing for two projects: the Oxide Stockpiles Project (OSP) and the Tailings Reprocessing Project (TRP). The report’s mineral resource estimates for tailings and oxide stockpiles are effective 30 September 2021, with a mineral reserve estimate for oxide stockpiles effective the same date.
Processing route
Oxide Stockpiles Project (OSP)
The proposed processing route for the oxide stockpiles involves a multi-stage plant designed to recover copper, gold, and silver. The flowsheet, as described in Section 17.0, includes the following stages:
Ore crushing and grinding is the first step, reducing the stockpiled material to a suitable particle size. This is followed by pulp talc flotation to remove talc, which can interfere with downstream processes. The pulp then undergoes acid leaching to dissolve copper, with the pregnant leach solution directed to copper filtering and solvent extraction. Copper electro-winning produces copper cathode.
The residue from copper recovery is then subjected to lime neutralization prior to gold and silver recovery via pulp cyanide leaching. Gold and silver are recovered through a combination of carbon-in-column (CIC) and carbon-in-pulp (CIP) circuits, followed by gold-silver stripping, electro-winning, and foundry operations. A DETOX step is included for cyanide destruction before tailings disposal.
Oxide Stockpiles Metallurgical Testwork
Section 13.2 describes the mineralized nature of the oxide stockpiles; however, the report does not provide specific metallurgical test results or recovery assumptions. The processing description is presented as a proposed design based on historical plant operations from the former Don Mario mine, but no detailed testwork data or performance criteria are supplied in the extracted text.
Tailings Reprocessing Project (TRP)
Section 13.4 covers the tailings metallurgical characterization. The report states that the tailings were sampled and subjected to metallurgical testing, but the specific procedures, reagents, or results are not detailed in the provided text. No recovery methods or flowsheet design for the TRP are given beyond the characterization study; the report text indicates that this was a preliminary step.
Key reported parameters
| Parameter | Value | Basis | Units |
|---|---|---|---|
| Report effective date | 28 February 2022 | Design | Date |
| Resource effective date (tailings & oxide stockpiles) | 30 September 2021 | Design | Date |
| Reserve effective date (oxide stockpiles) | 30 September 2021 | Design | Date |
| Processing plant description (OSP) | Crushing, grinding, talc flotation, acid leach, SX-EW, cyanide leach, CIC/CIP, stripping, detox | Proposed design | Not applicable |
| Metallurgical testwork (tailings) | Characterization only; no performance results | Testwork | Not applicable |
| Historical operating data | Referenced but not quantified in provided text | Historical | Not applicable |
Project website: https://www.orvana.com/English/operations/don-mario-district/history/default.aspx
Technical qualifications
The report contains several limitations that constrain the usefulness of the processing sections:
- No metallurgical test results are presented for either the oxide stockpiles or tailings, meaning recovery assumptions, reagent consumptions, or throughput rates are not substantiated by data in the provided text.
- The processing flowsheet for the OSP is described but not supported by a mass balance, equipment list, or engineering design criteria.
- For the TRP, the report notes only that metallurgical characterization was undertaken; no process design or recovery methodology is described.
- The text references historical plant operations, but no specific historical performance data are included, making it impossible to validate the proposed design against past experience.
- The report does not provide capital or operating cost estimates in the excerpted sections, nor does it include an economic analysis.
The limitations above mean that the processing sections should be treated as conceptual designs or descriptions rather than feasibility-level engineering. The absence of supporting testwork data and cost information precludes independent assessment of the technical viability of the proposed recovery methods.
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Source: National Instrument 43-101 Technical Report for the Don Mario Property, Eastern Bolivia, San Juan Canton, Chiquitos Province, Santa Cruz Department, Bolivia, effective 28 February 2022, issued 15 March 2022, Sections 13.0, 17.0, and related subsections.
