The Kibali gold project, one of the largest gold mines in Africa, offered project management company DRA an excellent opportunity to demonstrate its competence in the Democratic Republic of Congo.

The project, a joint venture between Africa-focused gold producer Randgold Resources, gold mining company AngloGold Ashanti and Congolese parastatal Sokimo, will increase production to about 600 000 oz/y of gold.

Located 17 km from Watsa, in the administrative district of Haut-Uélé, in Orientale province, the mine consists of openpit and underground sections. Its probable mineral reserves are estimated at 82-million tons, total- ling 11.5-million ounces of gold. About 45-million tons are designated to be mined openpit and 37-million tons through underground methods.

First Gold Construction of the mine comprises the design, procurement and construction of the metallurgical facility, hydropower stations and a backup thermal power facility; construction of the tailings storage facility; the relocation of villages; openpit mining; a decline complex; a vertical shaft; and the shared infrastructure.

First gold production is set for the fourth quarter this year.

DRA’s initial scope of work includes the design, procurement and project management of the metallurgical plant; infrastructure, including roads, dams, mine offices, stores, laydown areas and extending the airport runway; a 45 MVA backup power system; a tailings system for a 6.1-million-ton lined concentrate tailings dam and a 7.6-million-ton float tailings dam; and a 22 MVA hydropower plant.

DRA is responsible for the detailed engineering and construction management of the intake weir, canal, penstocks and hydropower house.

The largest of the four stations is situated 30 km from the mine at the confluence of the Nzoro and Kibali rivers. There are three smaller stations on the Kibali river. The 22 MVA station is a runoff river scheme, which requires the intake of the river through a 4.5 km canal, feeding two penstock lines 3.5 m in diameter and 1.2 km in length.

The hydroelectric power will be augmented by a backup power system during the dry season and for the start-up of high dynamic demand systems, like the mill installation.

The backup system comprises 30 diesel generators, each with a capacity of 1.5 MVA, which were supplied and installed by generator producer APS, with the support services engineered by DRA. The main fuel farm, with a capacity of 2 600 m3, will supply the generator farm and service the mining operations and vehicle fleet. Two additional fuel farms, each with a 1 200 m3 storage capacity will be built to service the opencast and underground mining sections.

DRA’s scope of work on the processing plant design will initially treat 3.6-million tons a year of oxide ore through the oxide circuit and 3.6-million tons a year of sulphide ore through the sulphide circuit.

The oxide circuit will comprise the following subprocesses: primary crushing, milling, gravity concentration, flash flotation, carbon-in-leach, detox and tailings disposal.

Crushing The sulphide circuit will include primary and secondary crushing, milling, gravity concentration, flash flotation, rougher flotation, concentrate handling (thickening and ultra-fine grinding), a pump cell circuit and tailings disposal.

The loaded carbon from the pump cell circuit and carbon-in-leach circuit will be batch-treated separately in elution circuits, followed by the electrowinning of gold eluate.

On completion of the Karagba-Chauffeur-Durba oxide reserves, the oxide circuit will be used as a dedicated sulphide circuit and then added to the existing sulphide stream to enable the combined treatment of sulphide ore at 7.2-million tons a year.

Satellite oxide reserves will be campaign-treated in the oxide circuit when a suitable campaign volume is stockpiled.

The Kibali gold project is currently in the execution phase, with earthworks nearing completion and the first steel being erected.