The government of the Democratic Republic of Congo has unveiled details of a controversial $9.25bn agreement that pledges millions of tonnes of copper and cobalt to China in exchange for roads, railways and other infrastructure.

The deal, finalised last month, could prove one of Beijing's most ambitious forays into Africa yet. On paper it secures 10.62m tonnes of copper and 620,000 tonnes of cobalt for resource-hungry Chinese industries, but this is dependent on overcoming operational challenges that are as great as anywhere in Africa.