Gold mining in DRC, from the ore to the bar

Deep down, a miner in a rural artisanal gold mine chisels gold ore out of the earth. The shaft team is composed mainly of excavators and bag porters. Miners spend six to eight hours down the shafts each day. The work is physically demanding. At this mine, around 200 kilograms of ore must be excavated to extract one gram of gold

A miner maneuvers through a narrow tunnel junction, as his colleague waits in line. The bags of ore he has been heaving through the mine, in the direction of the mineshaft entrance, are in front of him. After agriculture, artisanal mining is the most important livelihood in the eastern Democratic Republic of the Congo (DRC).

A bag porter carries his load downhill from the mine for processing. The porters are paid 500 Congolese Francs - about $0.35 (0.29 Euros) at current Eastern Congo exchange rates - per bag by the shaft managers, and can make up to several dollars per day. They are among the lowest earners at the mine and, at this site, are often those who have migrated from other areas.

A man kneels in front of a rock slab while breaking down gold ore with a grinding stone. Next, the remaining ore is manually ground down between two rocks to release the gold. This is a slow and arduous process; one plastic basin can take several hours to work through. Water carriers and ore porters are visible moving up and down the mine hill, in the background.

A man pours ore onto a sluice. The fine ore purchased by specialist sluice teams is mixed with water and poured onto sluices. Due again to its high density, the remaining gold sediment sticks to the sluice blanket while the excess flows downhill. The sediment is then gathered and sieved in a plastic basin using mercury.

A local on-site trader assesses how much to offer for the gold a client has brought him. The gold and mercury compound seen in the trader’s plastic dish is a dull metallic grey at this point in the treatment process. Many miners will look to sell these small gold quantities to on-site traders.

A 'big trader' heats the gold and nitric acid over a hot stove to rid it of any remaining impurities. Big traders deal in far larger quantities of gold than the local traders; they frequently trade more than several kilograms of gold in one week. Their profit margins are smaller than the local traders, but they trade in greater volume, which assures them a much higher income.

After heating, the gold is weighed on an electric scale. At this stage, the gold has reached between 92 and 98 percent purity, depending on its origin.

Once melted, the gold is cast in an ingot mould. After removing the red-hot crucible from the furnace, a worker at the gold smelter pours the molten gold into a graphite ingot mould for casting. Inside the furnace, the gold reaches temperatures of 1,500 degrees Celsius. It takes around 20 minutes to melt several kilograms of gold.

A freshly cast gold ingot is deposited by a worker on the work surface; the ingot mould remains smoking hot.

With a gold content of 4.163 kilograms, this ingot has a market price on the London Fixing of about $167,056 (about 145,000 euros) on the day it was produced. Annual gold production in the eastern DRC has been estimated at more than 11 tons, but most continues to be smuggled out of the country. In 2015, official artisanal gold exports for the DRC were recorded at just 254 kilograms.