July 03 2014

From ground to grams: The mining process

The way our gold makes it's way from ground to grams is generally the same, but on a different scale. While some small scale gold mining involves digging big pits, what we saw in the mines up for fair trade certification in Kenya & Tanzania were shafts. As for the shafts themselves, they are reinforced with timber.

The miners digs along gold veins and 50 kilo sacs of ore are hauled up from the holes, as shown above. Once a vein of ore is discovered, the miners follow it horizontally. How far they depends the go depends upon the type of ore that they are digging. Cave ins are not uncommon. I spoke with one of the local miners who told me the story how he was trying to take care of a number of orphaned children of dead miners.

Here’s a close up of rock ore. When you hold it, it feels much heavier than a normal piece of rock. The amount of gold in a piece of ore varies, but a typical amount would be an ounce of gold per ton of rock, which may take a day to dig. But these numbers really depend upon the particulars in a given site. Some of the mines we visited had more than one pit going.

There are thirty-one grams of gold in a troy ounce and each one of these bags in this photo might contain a gram or more of gold.

Often the rock that is hauled up needs to be dried out. Shown here is a woman spreading out the ore to dry in the sun.

After the rock is crushed (above), the gold is concentrated in the dirt. This is done through sluices in containment ponds, as shown below.

The next step involves mixing the gold with mercury. Mercury attaches to the gold and forms an amalgamation. These photos show how it is typically done.


In the first, the man is mixing mercury and the concentrated dirt with his bare hands. The second shows a safe method by a worker at one of the mines trying to attain fair trade certification.

Now, the gold ends up looking like this. This photo was from a mining group that was not committed to working toward fair trade gold certification. Mercury is so toxic that if someone broke a mercury thermometer in a high school science class they’d call a hazmat team in! People who work with mercury in these mines do not really believe that it is that dangerous. Next, the typical unregulated miners would take the gold and mercury and put it in a pan to burn off the mercury. This releases methyl mercury, a high dangerous toxic gas that stays in the environment. The pan they used to cook off the mercury is often utilized for cooking afterwards.

However, with fair trade mines, a mercury retort, as shown here, is used, which cools the gas and converts it back into mercury which can be reused. No one feels good about the mercury issue. But it is very difficult to get small scale miners to abandon mercury. Over time, with Fairtrade, the goal is to get small scale miners off mercury completely. But in building capacity and employing best practices, we have to start with where the miners are. Using cyanide is a better practice.

It is also possible to get the gold without chemicals. To do this requires equipment that costs about $20,000. Miners who sell the gold they extract as soon as they have it are never going to accumulate that kind of capital. Which is where Cred steps in...