Gold Recovery Methods at Kinross Paracatu Mine, Brazil

Source: Kinross Gold Corporation (2026)
Website: https://www.kinross.com/operations/default.aspx

Critical Data

Overview

Kinross Gold Corporation operates the Paracatu Mine in Brazil, employing a sophisticated combination of two processing plants (Plant I since 1987 and Plant II since 2008) along with a hydrometallurgical facility for gold recovery. The operation also reprocesses tailings through the PSAT and PET projects initiated in 2015. Located in the state of Minas Gerais, Paracatu is one of the largest gold mines in South America. The significance of this operation lies in its ability to process refractory gold ore through an integrated flowsheet that includes crushing, grinding, classification, flotation, gravity concentration, and carbon-in-leach (CIL) cyanidation. The process begins with primary crushing using an MMD toothed sizer that reduces ROM ore from 1,300 mm to 350 mm, followed by stockpiling. Plant I uses conventional ball mills and flotation, while Plant II features a large 20 MW SAG mill and four ball mills totaling 28 MW. Gold recovery is enhanced by gravity concentration using Knelson concentrators and intensive leaching. The hydrometallurgical plant treats flotation concentrates through pre-aeration, CIL leaching with a residence time of 25 hours, and carbon elution at 140°C. Final gold recovery is achieved via electrowinning and smelting into doré bars. Environmental management includes ISO 14001 and 45001 certifications and compliance with the International Cyanide Management Code.

Key Process Stages

• Stage 1: ROM Crushing and Stockpiling – Ore from the open pit is dumped into a 480 t hopper and fed to an MMD 1300 Series Twin Shaft Sizer that reduces rock from 1,300 mm to 350 mm. Crushed ore is conveyed to a covered stockpile with 45,000 t live capacity (expandable to 282,000 t using dozers). Six variable-speed belt feeders reclaim ore from the tunnel.
• Stage 2: Grinding Circuit – Plant II uses a 11.6 m × 6.7 m SAG mill (20 MW) in closed circuit with trommel and vibrating screens to produce slurry at 70-74% solids. Pebbles are recycled or sent to Plant I. Secondary grinding uses four ball mills (two 7.3 m × 12.2 m at 2×6,500 kW and two 7.9 m × 12.8 m at 2×7,500 kW) in closed circuit with hydrocyclones targeting a P80 of 190 µm. Plant I uses six mills (four primary ball mills at 3,500 kW each, one secondary ball mill at 3,500 kW, and one rod mill at 1,000 kW) achieving P80 < 160 µm.
• Stage 3: Flotation and Gravity Concentration – Rougher flotation in four lines (six cells each) produces a gold-bearing concentrate. The first rougher concentrate feeds gravity concentration via Knelson concentrators (three QS48 units in Plant II). Cleaner flotation (two lines, five cells each) upgrades the concentrate, which is then thickened and reground in a vertical mill to 90% passing 45 µm. Gravity tailings return to the ball mill discharge or flotation feed.
• Stage 4: Hydrometallurgy – CIL Leaching – Flotation concentrate is pre-aerated in two tanks (707 m³ each) with oxygen and lime to adjust pH to 9.8-10.5. Seven CIL tanks (750 m³ each, 10 m diameter) operate with a total of 200 t of activated carbon and a residence time of approximately 25 hours. Cyanide concentration starts at 500-800 ppm and drops to 100-150 ppm in the last tank. Loaded carbon is recovered via interstage screens and transferred to acid wash and elution.
• Stage 5: Elution, Electrowinning, and Refining – Loaded carbon undergoes acid washing (3% HCl for 3 hours) then elution (0.2% NaCN, 2-3% NaOH at 140°C, 300 kPa for 10-12 hours) in two 36 m³ columns. The rich solution feeds electrowinning cells (four stainless-steel cathodes at 80-90°C). Gold sludge is calcined at 700°C for 12 hours, then smelted with fluxes at 1,200°C in an induction furnace to produce doré bars. Carbon is regenerated in two 600 kg/h rotary kilns at 700°C. Cyanide destruction via SO₂/O₂ (detox) ensures tailings discharge meets environmental limits.

Additional Interesting Data and Summary

The Paracatu Mine’s gold recovery methods integrate multiple unit operations tailored to the refractory nature of the ore. Plant I, operational since 1987, uses conventional ball milling and flotation with a target grind P80 of 160 µm, while Plant II, added in 2008 and expanded with two additional ball mills in 2011–2012, processes higher throughput with a SAG mill–ball mill configuration. The gravity circuit in Plant II processes approximately 13% of the ball mill circulating load using four Knelson QS70 concentrators, with additional Knelson QS48 units treating first-rougher concentrate. The hydrometallurgical plant handles both flotation and gravity concentrates via the Acacia reactors (CS2000 and CS8000, with capacities of 8 t/d and 32 t/d respectively) for intensive leaching prior to CIL. Key process parameters include pre-aeration pH of 9.8–10.5, CIL cyanide concentration from 500 to 150 ppm, and elution temperature of 140°C. The detox circuit uses the SO₂/O₂ method to destroy free and WAD cyanide before tailings disposal. Environmental stewardship is a priority: the site holds ISO 14001, ISO 45001, and International Cyanide Management Code certifications. Water quality management is critical due to naturally occurring arsenic and sulphides; the operation implements a Basic Intervention Plan that has reduced metal concentrations in local streams. Human Health Risk Assessments guide remediation efforts. The mine’s tailings reprocessing projects (PSAT and PET) since 2015 further enhance recovery and reduce environmental footprint. With a total installed grinding power exceeding 48 MW across both plants, Paracatu continues to optimize energy efficiency and gold recovery. Future outlook focuses on sustaining production through brownfield expansions, improving water recirculation, and maintaining regulatory compliance. The facility’s significance lies in its ability to consistently recover gold from low-grade, refractory ore, making it a benchmark for large-scale gold mining in South America.

Key Processes: Flotation, CIP/CIL, Cyanidation, Gravity Separation, SAG Mill, Ball Mill, Crushing

Target Commodities: Gold