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MEI Online: Plant Operation News: Africa: October 4th 2005


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:: Zenzele Technology Demonstration Centre

A small but novel development is taking place at O'Kiep, site of one of the oldest copper mines in Africa, located near Springbok in the Northern Cape province of South Africa. The ore body, an oxidised deposit of copper carbonates and silicates, has been considered as being "worked out" but an initiative by Zenzele Technology Demonstration Centre (a non-governmental organisation which assists artisanal and small-scale mining operations) is extending the life of the remaining ore body for a further 20 years and is benefiting the indigenous Griqua population at the same time.

Ore is handpicked from the old dumps, and then hand-sorted into fractions containing 5 to 10 % copper. This ore is crushed in a jaw crusher and then batch leached in sulphuric acid to yield a solution containing about 40 g/l Cu. The leach liquor is refined by means of solvent extraction (SX) to separate copper from iron and other impurities.

AARL was approached in 2003 to assist with the process and equipment design for the SX operation. Anglo Technical Division was subsequently involved in providing an engineering cost and design for the project.

Using technology first demonstrated by the TDC, the purified liquor from the SX circuit then becomes the electrolyte in a special electrochemical cell designed to electroform a variety of copper artefacts.These include items such 35 bowls, ornaments, plaques, and jewellery, which are sold into the tourist market and for export. The decision to electroform artistic pieces, rather than electrowin copper cathode (as would be conventional practice), means that the value of the copper produced by the project increases from about R20 000/t to as high as R250 000/t. Although the value add is primarily due to the artistic characteristics of the electroformed products, the electroforming could not be carried out without the inclusion of the SX circuit to purify the electrolyte.

View of Copper SX circuit
View of Copper SX circuit

The project provides jobs for some 20 people who would otherwise be unemployed in this impoverished area. This small plant is currently producing about 0.5 t/per month copper in a development that provides a unique combination of first- and third-world technologies, to the benefit of people of both worlds.




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