RPA's March 2016 technical report for Barrick on the Lagunas Norte mine in Peru's La Libertad region also outlines the Refractory Project PFS, which would add flotation, pressure oxidation and CIL.
The Technical Report on the Lagunas Norte Mine, La Libertad Region, Peru, was prepared by RPA Inc. for Barrick Gold Corporation and dated March 21, 2016. The operation uses two-stage crushing, heap leaching, and a Merrill-Crowe zinc cementation plant with carbon-in-column (CIC) to recover gold and silver. The other main components are a refinery and a water discharge treatment plant.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Report date | March 21, 2016 | Not applicable | RPA Inc. for Barrick Gold Corporation |
| Crushing capacity | 42,000 t/d design, 63,000 t/d permitted | Not applicable | Not applicable |
| Primary stockpile | 2,000 | t live | Not applicable |
| Secondary crushers | Two MP800 | Not applicable | Product P80 about 50 mm |
| Ore bin | 1,000 | t live | Trucks haul ore to the pad |
| Lift height | 10 | m | Placed by GPS-guided dozer |
| Irrigation rate | 10 to 20 | L/m²/h | Drip, with raincoats |
| Solution to pad | 3,000 m³/h, rising to 4,300 m³/h with CIC | Not applicable | Not applicable |
| CIC plant | 1,800 m³/h average, 2,140 m³/h design | Not applicable | Operating since August 2013 |
| Cyanide destruction | 117 kg/h WAD cyanide | Not applicable | About 600 m³/h of barren solution |
| ARD treatment | 1,500 | m³/h | Botadero Este plant |
Overview
The crushing circuit was designed for 42,000 t/d, and the permit allows 63,000 t/d. Historically, gold recovery from the Lagunas Norte heaps has not depended much on crush size, so the crush has been coarsened over time to put more ore through. Each pad has its own pregnant leach solution (PLS) pond and pumps, and solution can go to the Merrill-Crowe plant, the CIC plant, or both. Part of the pregnant solution and sediment pond water is recirculated to the pad, raising the flow to 3,000 m³/h to hold the optimum solution-to-ore ratio or to control the water balance.
Key Process Stages
Crushing. Haul trucks tip directly into a gyratory crusher, with a rock breaker at its mouth. An apron feeder and conveyor carry ore to a 2,000 t live stockpile. A splitter divides it between two lines, each with a double-deck screen and an MP800 secondary crusher producing P80 of about 50 mm. Product goes to a 1,000 t live bin, from which haul trucks take it to the pad. Lime is added to the trucks to raise the pH of the leach solution.
Heap leaching. Ore is stacked in 10 m lifts. A GPS-guided dozer pushes material over the edge to keep a level surface and limit segregation. Each finished cell is ripped to break up the surface compacted by the trucks. Contaminated ore is stacked separately, some of it crushed and some not. Drip irrigation applies cyanide at 10 to 20 L/m²/h. Because the site has a net positive water balance, raincoats limit the water entering the circuit, and runoff from them goes to six raincoat ponds. It can be discharged untreated if WAD cyanide is below 0.1 ppm.
Merrill-Crowe. CIC desorption solution is mixed with PLS ahead of the Merrill-Crowe plant. Solids are clarified out, a deaerator lowers dissolved oxygen below 1 ppm, and zinc dust precipitates the gold and silver, which filter presses recover. Barren solution is dosed with cyanide and antiscalant and returned to the pad.
Carbon-in-column. The CIC plant, operating since August 2013, treats an average of 1,800 m³/h, with a design flow of 2,140 m³/h. It lets the solution flow to the pad rise to 4,300 m³/h, and the spare 2,000 m³/h washes areas where leaching is complete.
Refining. The precipitate is dried in mercury retorts, where mercury is evaporated, condensed and recovered under vacuum. It is then fluxed and smelted to doré, which is sent to an outside refinery.
Water treatment. When there is surplus solution, barren solution is detoxified by the SO2/air process with sodium metabisulphite and copper. Acid rock drainage from the east waste rock facility is oxidized, pH-adjusted and clarified. The two streams are combined, raised above pH 8.7 with lime to precipitate metals, brought to about pH 7.0 with sulphuric acid and held in a polishing pond until assays confirm the water can be discharged. A secondary treatment plant further improves the discharge quality.
Additional Interesting Data and Summary
The report also outlines the process flowsheet of Barrick's Refractory Project PFS. It would add new processing facilities while reusing or upgrading some existing plant: blending stockpiles, a SAG mill, desliming cyclones, flotation, a pressure oxidation (POX) autoclave, CCD thickeners, neutralization and CIL, with the existing CIC plant, refinery and cyanide detoxification plant used for gold recovery. Its concentrator, POX and leaching, and water treatment would each have their own site, and its filtered tailings would be dry stacked on the leach pad or used as a desulphurized cover on the waste rock pile.
In summary, Lagunas Norte is a large crushed-ore heap leach in a wet climate. It recovers gold by both Merrill-Crowe and CIC and runs a substantial water treatment system, and the Refractory Project PFS looks at a new mill with flotation and POX to treat the sulphide ore beneath the oxides.
Key Processes
- Gyratory and cone crushing to P80 about 50 mm
- Truck haulage and 10 m lift stacking with dozer placement
- Drip-irrigated cyanide heap leaching under raincoats
- Merrill-Crowe zinc cementation
- Carbon-in-column adsorption
- Mercury retorting and smelting to doré
- SO2/air cyanide destruction and ARD treatment
- Refractory Project concept: SAG, flotation, POX, CCD and CIL
Source: Technical Report on the Lagunas Norte Mine, La Libertad Region, Peru, prepared by RPA Inc. for Barrick Gold Corporation, March 21, 2016.
Earlier report summaries
Earlier versions of this profile, based on older technical reports, are retained below for source traceability. Dates and figures reflect each report’s own effective date and are superseded by the current information above.
Lagunas Norte Mine — 2012 Technical Report
This technical report describes the mineral processing and metallurgical testing program for the Lagunas Norte gold mine in the La Libertad Region, Peru.
Report context
This technical report, dated March 16, 2012, was prepared for Barrick Gold Corporation under NI 43-101 standards. The report documents the mineral resource and reserve estimates, mining methods, and recovery methods for the Lagunas Norte operation. The project number is 1681.
Processing route
Process Description
The recovery methods section of the report describes the process employed at Lagunas Norte. The report contains a section titled "Process Description" under Section 17 Recovery Methods, but does not include detailed flowsheet diagrams or specific equipment listings.
Metallurgical Testing
Section 13 of the report covers Mineral Processing and Metallurgical Testing. The metallurgical testing program was conducted to support the process design and operational parameters for the operation. No specific testwork results, sample types, or laboratory details are provided in the extracted evidence.
Mineral Resource Estimation
The resource estimation methodology incorporates geological models, geological domains, grade domains, density data, cut-off grades, assay statistics with capping of high grades, compositing, contact plot analysis, variography, and resource estimation validation procedures. Resource classification criteria are defined, and resource estimates are validated using established techniques.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Project Number | 1681 | Report identification |
| Report Date | March 16, 2012 | Issue date |
| Mine Location | La Libertad Region, Peru | Report scope |
| Owner | Barrick Gold Corporation | Client |
| Report Standard | NI 43-101 | Regulatory framework |
| Resource Classification | Defined | Report Section 14 |
| Reserve Estimation | Included | Report Section 15 |
| Mining Method | Open pit | Report Section 16 |
| Recovery Method | Process description | Report Section 17 |
Project website: https://www.barrick.com/English/news/news-details/2021/barrick-reaches-agreement-to-sell-the-lagunas-norte-mine/default.aspx
Technical qualifications
The technical report was prepared as a National Instrument 43-101 compliant document. The processing sections reference a "Process Description" but do not provide complete flowsheet details, performance data, or specific equipment specifications. The metallurgical testing section is referenced as Section 13 but detailed testwork results are not included in the available evidence. The report is based on information available as of March 2012 and does not show subsequent operational changes or developments.
Source: Technical Report on the Lagunas Norte Mine, La Libertad Region, Peru, NI 43-101 Report, March 16, 2012, Sections 13, 14, 15, 16, and 17.
