The 2022 feasibility study for the Tocantinzinho Gold Project describes a processing plant designed for a nominal 4.34 Mt/y of granite ore, with the ability to treat up to 4.70 Mt/y when saprolite and garimpeiros tailings are included in the blend.
Report context
This technical report was issued in February 2022 as a National Instrument 43-101 feasibility study for the Tocantinzinho Gold Project. The document presents the proposed processing route and associated infrastructure for a gold operation located in the state of Pará, Brazil, with the process design based on granitic run-of-mine ore supplemented by limited quantities of saprolite and historical garimpeiros tailings.
Processing route
The proposed process plant includes comminution, gravity concentration, gold flotation, cyanide leaching with carbon adsorption via carbon-in-leach (CIL), carbon elution, and gold recovery. CIL tailings are directed to a cyanide destruction circuit and dewatered to produce a slurry for onsite storage. The plant feed comprises run-of-mine granite ore, with minor amounts of saprolite and garimpeiros tailings added when available.
Comminution
Primary crushing of run-of-mine material is followed by a coarse ore stockpile with reclaim. Grinding is accomplished using a semi-autogenous (SAG) mill and a ball mill with hydrocyclones, producing a final product with a P80 of 125 µm.
Gravity concentration
A gravity concentration circuit produces a gold-rich concentrate intended for intensive leaching, with subsequent gold recovery via electrowinning. No further details of the gravity circuit configuration are provided in this section.
Flotation
A two-stage flotation circuit operates at an average mass pull of 4.5% to produce a sulphide concentrate destined for cyanide leaching. The concentrate is the primary feed to the downstream leaching circuit.
Leaching and adsorption
The process includes pre-leach, cyanide leaching, and carbon adsorption in a CIL circuit designed with 36 hours of residence time to achieve optimal gold extraction. Carbon elution is performed using a 3 t Pressure Zadra circuit, with supporting carbon handling and regeneration facilities.
Gold recovery
Electrowinning and smelting are used to produce doré bars. No additional recovery steps are described.
Tailings management
Cyanide destruction of CIL tailings uses the SO₂/air process. Flotation tailings and concentrate cyanidation tailings (i.e., CIL tailings) are stored in separate tailings storage facilities.
Ancillary systems
The plant includes air and oxygen circuits, along with water systems covering potable water, raw water, gland seal water, and process water.
Key reported parameters
| Parameter | Value | Unit | Basis |
|---|---|---|---|
| Nominal plant throughput | 4.34 | Mt/y | Design |
| Maximum plant throughput (with saprolite/garimpeiros tailings in blend) | 4.70 | Mt/y | Design |
| Maximum saprolite/garimpeiros tailings feed rate | 1,000 | t/d | Design limit |
| Grinding product size | 125 | µm (P80) | Design |
| Flotation average mass pull | 4.5 | % | Design |
| CIL residence time | 36 | hours | Design |
| Carbon elution circuit | 3 t Pressure Zadra | , | Design |
| Cyanide destruction process | SO₂/air | , | Design |
Project website: https://gmin.gold/tocantinzinho/
Technical qualifications
The report identifies that the process plant feed will include small quantities of saprolite and garimpeiros tailings, but the design basis limits this additional feed to 1,000 t/d. The described flowsheet and parameters are proposed design values; the report does not provide historical operating data for these circuits at this site. Figures referenced in the original report (overall flowsheet, plant layout, site view) are not reproduced in this summary, and the associated details are only available in the complete technical report.
Source
Feasibility Study – NI 43-101 Technical Report, Tocantinzinho Gold Project, Section 1.15 Recovery Methods, February 2022, pages 1-14 to 1-15.
