When Shituru mines in Likasi Congo needs to deliver copper they look to us.
Likasi in Congo DRC is in part of its mining heartland. One of the copper mines in Likasi is Shituru. At Shitaru, like many of the copper mines in Congo, ore is reached via huge open pits some measuring tens of kilometers apart. We sit down with the mine's production engineer, Mark Kasanda and he talks shop with us
‘You can always be better than yesterday. Our company is here to increase production while still doing it a responsible fashion to mother nature and our local community.’
The process of extraction copper from the ground is pretty much the same once the ore has been extracted from the ground – The barren rock, or gangue has to be separated from the copper ,which is in various sulfide minerals,in order to smelt the metallic copper from the ore. By far the greatest proportion of copper is extracted from the sulfides of copper, iron and sometimes other metals.
Ores are first mechanically crushed and ground so that nearly all copper mineral particles are freed from the gangue. Flotation and violent agitation is carried out on the pulverized ore held in suspension in water. The process yields concentrates containing roughly 30% copper, which is then fed to a smelter, a furnace in which most of the some iron and sulfur are removed, then to a converter or converting furnace, where most of the remaining iron and other impurities are removed.
800,000 tonnes of ore is processed annually
The copper concentrates are fed through the flash smelting furnace with oxygen-enriched air. In the furnace, the concentrates are instantly oxidized, after which they melt and separate by their own reaction heat into copper matte with a grade of 65% and slag consisting of iron oxide, silica, and other compounds.
The matte produced by the flash smelting furnace is transferred to the Converter furnace. Oxygen-enriched air is blown into the Converter furnace to oxidize the matte further to create blister copper with a grade of approximately 99%.
‘Nothing is wasted in these reactions. Heat is recycled to run the plant while gases are collected and packaged.’
The refined blister copper is poured into casting molds lined up side by side on the revolving circular table of a casting wheel and cast into anode plates for electrolytic refining. The anode plates are approximately 1m x 1m x 0.05m in size, and weigh 380 kg per plate.
Mine produces 35,000 tonnes of LME grade cathode copper
Anode plates and stainless steel cathode plates are alternately set into the electrorefining cell, where a proper level of DC current is supplied. Dissolved copper from the anode is electrolytically deposited on the stainless steel cathode plate. After about 10 days of electrolysis, the cathode is lifted out and stripped from the stainless steel plate, resulting in the completion of refined copper (with grade of 99.99%) as a final product.
The refined copper is shipped in stacked bulks, which are 1m in length and width and approximately 80kg in weight.
‘We have not always had this level of production. It has taken us a few years to get the right equipment, improve processes and of course the right people. As the business grows, you find out pretty quickly you can’t do everything.’
‘Either your company stays one size or, like us, it grows and you need to adapt. You have to trust the people around you.’
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