Modern Mining June 2019

POWER SUPPLY AND ENERGY EFFICIENCY

at the Hydro 18 conference and exhibition, held in Gdansk, Poland, in October last year. It was authored by John Steele, Metallurgy, Engineering and Capital Projects Executive of Barrick, Robert Greyling of Knight Piésold (South Africa) and Egbert Scherman of Knight Piésold (Vancouver). As described by the authors, Azambi – on the Kibali River – is configured as a run-of- river type hydropower station, operating over a gross head of 14,7 m and a design flow of 106 m 3 /s. It comprises a rubble masonry con- crete (RMC) gravity diversion weir, a reinforced concrete (RC) intake structure, a 1,06 km long power canal and RC powerhouse and tailrace, equipped with two Kaplan turbine and generat- ing units, an 11 kV switchyard and a 7 km long, 66 kV transmission line. The project headworks are positioned at an outside bend of the river, at a location where a small island divided the river naturally. The diversion weir axis was aligned across this island and approximately perpendicular to the river channel and the regional dip of rock strata. This greatly simplified channelling and river diversion during construction and also minimised the overall extent of the foundation preparation works required for the weir. Commenting on the application of RMC for the small weir structure (with a maximum height of 6 m and a 185 m long, concrete-lined ogee spillway), the authors say this proved to be very successful. “Whilst promoting cost sav- ings compared to a mass or reinforced concrete equivalent, it offers a durable structure that is resistant to flood damage, constructed using high labour utilisation. The selected layout also

of hydro

They are connected to the mine via a 66 kV overhead line network. The Nzoro 2 station was completed in 2014, Ambarau in early 2017 and Azambi in July 2018. It should be mentioned that there is a fourth small hydro-electric station, Nzoro 1, a ‘legacy’ 1 MW installation from the colonial era, which has been refurbished and is now dedicated to supplying power to the local community. Azambi, the most recent of the stations to be completed, was the subject of a paper presented

Above left: Azambi – on the Kibali River – is configured as a run-of-river type hydropower station.

Below left: The scene at last year’s opening of Azambi.

Below: Construction of Azambi was undertaken by Congolese contractors.

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June 2019  MODERN MINING  41