Kibali Gold Mine: Dual-Circuit Processing for High Gold Recovery

Source: Unnamed_Company_45 (2026)
Website: https://www.anglogoldashanti.com/portfolio/africa/kibali/

Critical Data

Overview

The Kibali Gold Mine, operated by AngloGold Ashanti in the Democratic Republic of the Congo, stands as one of Africa’s premier gold processing facilities. Located in the Moto Greenstone Belt, the mine has been in operation since 2013 and processes a geometallurgically diverse ore feed sourced from the KCD underground mine and satellite open pits. The processing plant employs two largely independent circuits—an Oxide and Free-Milling Circuit and a Sulphide Refractory Circuit—designed to handle ore types ranging from soft oxides to hard, gold-locked sulphides. This dual-stream configuration, with a combined design capacity of 7.2 Mtpa, has consistently exceeded throughput targets, treating 8.32 Mt in 2025. The significance of Kibali’s recovery methods lies in their operational flexibility: both circuits can process sulphide ore as needed, enabling a progressive transition to full sulphide processing as oxide sources deplete. Ore blending is central to the plant’s success, with daily scheduling based on grade, hardness, and sulphide content to homogenize feed and optimize metallurgical performance. Key processes include primary and secondary crushing, ball milling, gravity recovery using Knelson concentrators, flash and conventional flotation, ultrafine grinding (UFG) to a P80 of 23 μm, and cyanidation via CIL and Pumpcell CIP circuits. With excellent plant availability exceeding 95% and specific energy consumption reduced to 26.9 kWh/t, Kibali’s recovery methods demonstrate world-class efficiency and adaptability for complex gold ores.

Key Process Stages

• Stage 1: Ore Blending and Stockpile Management – Ore from multiple sources is segregated into dedicated stockpiles based on metallurgical domain (oxide, transition, sulphide). Real-time monitoring of volumes and grades via weighing systems and frequent assays enables daily blend scheduling to achieve target head grade, arsenic thresholds, and Bond Work Index. Blending optimizes grinding energy and flotation/leaching performance.
• Stage 2: Crushing and Grinding – Sulphide ore undergoes primary (Sandvik CJ815 jaw crushers) and secondary (Sandvik CS660 cone crushers) crushing to a P80 of 45 mm, then reports to a 11,700 t Fine Ore Stockpile. Oxide ore may bypass secondary crushing. Both circuits use ball mills in closed circuit with cyclones: oxide circuit target grind P80 80 μm; sulphide circuit target P80 75 μm. A hybrid roll crusher is available for harder transitional ore.
• Stage 3: Gravity Recovery and Flash Flotation – Cyclone underflow from both circuits passes through Knelson gravity concentrators to recover free native gold as a coarse concentrate. Flash flotation cells operate optionally when processing free-milling fresh ore. The gravity concentrate is leached in a Gekko Inline Leach Reactor (ILR), with pregnant solution sent directly to electrowinning.
• Stage 4: Flotation and Ultrafine Grinding (Sulphide Circuit) – Cyclone overflow reports to two parallel banks of six 70 m³ Outotec forced air flotation cells for rougher flotation. Rougher concentrate (combined with flash flotation concentrate) is thickened and then fed to eight FLSmidth VXP2500 ceramic bead mills in parallel, achieving an ultrafine grind P80 of 23 μm. This liberation step is critical for recovering gold locked in sulphide minerals.
• Stage 5: Leaching and Carbon Adsorption – The oxide circuit uses a conventional CIL circuit with nine tanks (two pre-oxidation with Aachen reactors, seven adsorption tanks). The sulphide circuit employs a pre-oxidation stage with Aachen reactors, extended leach in 2,100 m³ tanks, and eight 100 m³ Kemix Pumpcell tanks in carousel mode for CIP. Loaded carbon from both circuits is eluted via AARL 12-tonne batch circuits, with electrowinning and smelting producing doré. CIL tails are treated in a 4.8 Mtpa AZ-CRP® cyanide removal plant to meet ICMI standards.

Additional Interesting Data and Summary

The Kibali processing plant’s technical excellence is underpinned by robust power and water management. The site’s hydropower system delivers a peak of 42.8 MW, supplemented by 43 MW of thermal generation, providing full redundancy. Total mine load averages 41 MW, ensuring reliable operation. Water demand has stabilized at 11.5 Mm³ per annum, with a specific consumption of 1.38 m³/t, reflecting efficient recirculation and tailings management. Reagent consumption in 2025 highlights the plant’s optimized chemistry: cyanide averaged 0.638–0.672 kg/t, lime 1.138–1.314 kg/t, and grinding media 0.527–0.546 kg/t across quarters. The recently installed AZ-CRP® cyanide removal plant, with a capacity of 4.8 Mtpa, treats CIL tailings to comply with International Cyanide Management Institute (ICMI) standards while recovering additional gold and copper. Environmental sustainability is furthered by the use of hydropower, which reduces the carbon footprint compared to diesel generation. The plant’s workforce includes 570 direct employees and 245 contractors, with specialist partners for TSF management, plant cleaning, and oxygen production. Looking forward, as oxide and free-milling ore sources deplete, the existing oxide circuit will be converted to a parallel sulphide circuit, necessitating expansion of concentrate handling and Pumpcell capacity. The current feed plan already operates with 30% oxide–sulphide campaign per year, with the rest treating only sulphide ores. The original UFG section was expanded in 2017 to eight VXP2500 mills, and further upgrades are anticipated. The Qualified Person has confirmed that the current facilities are suitable for processing the ores outlined in the Life-of-Mine plan, underscoring Kibali’s long-term viability as a world-class gold producer.

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

Target Commodities: Gold, Copper, Lead