Furnas Copper Recovery: 37,000 tpd Flotation Concentrator Design

Source: Ero Copper Corp (2026)
Website: https://www.ero.com/what-we-do/furnas-project/

Critical Data

Overview

Ero Copper Corp. is developing the Furnas Project in Pará State, Brazil, a significant copper-gold deposit. The proposed concentrator, outlined in the 2026 Preliminary Economic Assessment (PEA), will employ a conventional copper flotation recovery process designed to treat 37,000 tonnes per day (tpd) of mineralized material. The plant flowsheet integrates primary, secondary, and tertiary crushing followed by ball mill grinding and a multi-stage flotation circuit to recover copper sulfides and associated gold. Key design features include a regrind IsaMill for ultra-fine liberation (P80 20 µm) and Jameson cell cleaner stages to produce a premium concentrate grading 30% Cu. Overall copper recovery is projected at 90.3% with gold recovery of 74.6%. The facility is designed for high operational flexibility with two parallel processing lines, each handling 18,500 tpd, and incorporates auxiliary gravity gold recovery to capture coarse free gold. Located in the Carajás mineral province, the Furnas concentrator will leverage existing regional infrastructure, including a 230 kV power supply from the Carajás Substation. The plant will also feature advanced water management with paste tailings thickening and a water surplus of 89 L/s, supporting sustainable operations. This comprehensive recovery method ensures maximum value extraction from the complex iron-rich altered zone mineralization containing chalcopyrite and pyrite.

Key Process Stages

• Stage 1: Primary Crushing – Run-of-mine ore with a maximum top size of 600 mm is fed into a 400 t hopper via apron feeders, then crushed by a Nordberg C200 jaw crusher (400 kW) at an instantaneous rate of 2,056 t/h. A rock breaker handles oversize material. The crushed product is conveyed to a 37,000 t live capacity stockpile, providing 24 hours of surge capacity.
• Stage 2: Secondary and Tertiary Crushing – Material from the primary stockpile is screened and crushed in two parallel lines. Secondary crushing uses Nordberg MP800 cone crushers (600 kW each) in closed circuit with 50 mm screens. Tertiary crushing employs four Nordberg MP2500 cone crushers (1,800 kW each) with closed-circuit screening to achieve a final product P80 of 12.5 mm. The fine ore stockpile also holds 37,000 t (24 hours autonomy).
• Stage 3: Ball Mill Grinding – Fine crushed ore (P80 9.5 mm) is fed to two 28 ft x 46 ft ball mills (22,371 kW each) operating in closed circuit with hydrocyclones. The target grind size is P80 106 µm at a nominal throughput of 37,000 t/d. The circuit operates with a circulating load of 350% and is designed based on a Bond work index of 16.48 kWh/t. Discharge solids content is 78%.
• Stage 4: Flotation and Regrinding – Rougher flotation uses twelve 160 m³ TankCells with a residence time of 20 minutes to recover 95-96% of copper. Rougher concentrate is reground in an IsaMill M15,000 (3,800 kW each) to P80 20 µm. Three stages of cleaning use Jameson cells to upgrade concentrate to 30% Cu. Scavenger flotation (twelve 50 m³ TankCells) recovers additional values, with concentrate recycled to regrinding. Overall copper recovery reaches 90.3%.
• Stage 5: Concentrate Thickening and Filtration – Final cleaner concentrate is thickened in an 11 m high-rate thickener to 65% solids, then filtered with vertical filter presses to 9% moisture. The final concentrate is conveyed to a 6,000 t stockpile for shipment. Recovered water from thickener overflow (56 m³/h) and filtrate (15 m³/h) is returned to the process water circuit, minimizing freshwater intake.

Additional Interesting Data and Summary

The Furnas concentrator’s design includes comprehensive supporting systems that enhance operational efficiency and environmental sustainability. The plant’s total installed power of 77 MW will be sourced from the regional grid via a 230 kV interconnection to the Carajás Substation, ensuring reliable electricity supply for the large-scale operation. Water management is a critical component: the concentrator consumes approximately 200 L/s, but due to the high precipitation regime in Pará State, the overall water balance shows a surplus of 89 L/s that must be treated before discharge. A backup water supply line of 100 L/s is specified for commissioning and dry periods. Process consumables are carefully estimated, including grinding media (600 g/t – 8,103 t/year of balls), flotation reagents (Matcol collectors, frother, lime at 100 g/t), and flocculants for thickening (25 g/t for concentrate, 30 g/t for tailings). The tailings management system integrates a paste backfill plant that uses filter presses to produce paste at 72% solids for underground stope backfilling, reducing surface tailings footprint. Tailings thickening employs high-density thickeners (40 m diameter) achieving underflow solids of 67-69% with a rheology of 100-200 Pa. The planned tailings storage facility has a capacity of 200 Mt. Economically, the 2026 PEA envisions a 13.5 Mt/a operation with a life-of-mine average copper recovery of 90.3% and gold recovery of 74.6%, producing a clean concentrate at 30% Cu and 9% moisture suitable for transport. Sustainability initiatives include maximized water recirculation (thickener overflows and filtrate returned to process), reduced freshwater intake, and lower energy intensity per tonne of concentrate. The future outlook for the Furnas Project is positive, with ongoing exploration for down-dip extensions and planned drilling in the central portion of the deposit. The two-line parallel configuration ensures high plant availability and operational flexibility, allowing for maintenance without full production shutdown. This robust recovery methodology positions the Furnas concentrator as a world-class copper-gold processing facility in Brazil’s Carajás mining district.

Key Processes: Flotation, Gravity Separation, Ball Mill, Crushing

Target Commodities: Gold, Copper