Hesperian Health Guides
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Heavy metals such as arsenic, mercury, cadmium, uranium, and lead are harmful to people even in very small amounts. Because many metals are found together at mine sites, it is often hard to know which metal may be causing health problems.
If you know what metals are likely to be found in your area and the health effects of these metals, this will help you know if you have heavy metal poisoning. Some miners demand testing from the mine operator to know what heavy metals they are exposed to, and training about ways to reduce harm.
Mercury is mined on its own and is also used to separate gold from ore.
Lead is often found with copper, silver and zinc.
Copper is found with silver and zinc.
Arsenic is often found with gold, copper, and zinc.
Cadmium is found with silver, copper, and zinc.
When artisinal miners process silver or gold ore, they often mix the ore with mercury to make a soft substance called amalgam. When burned off to collect the gold, the mercury turns to a gas that can be breathed in by anyone nearby. Mercury can also become a gas if it is spilled or left in an open container. Breathing in mercury fumes is very dangerous. Mercury is also dangerous if it is absorbed through the skin or eaten when it passes from someone’s hands to food.
Some signs of mercury poisoning are easy to confuse with malaria. If you live in a gold mining community and malaria medicine does not seem to work, talk to a health worker about the possibility of mercury poisoning.
Mercury poisons the environment by settling into the water and soil, where it can remain for many years. Lakes and rivers in California, USA, are still poisoned by mercury from gold mining over 100 years ago. (See “Mercury in fish.”)
Prevent mercury poisoning
Artisinal gold (or silver) miners can prevent mercury poisoning by using a mercury retort. A mercury retort captures mercury gas before it gets into the air. This prevents miners and others from breathing the poison, and allows miners to save money by reusing mercury rather than losing it to the air.
Always separate gold from mercury in the open air or in a well-ventilated area. This will reduce the amount of mercury fumes that collect on, and in, the bodies of people nearby. Wear thick gloves when handling mercury.
Some gold miners simply put a banana leaf over the gold heating pan to capture mercury. When heated, the mercury turns to gas, and turns back to liquid on the leaf. Covering the heating pan with a leaf is much better than leaving it uncovered. But this still allows the mercury to poison the worker and the environment, and the mercury is not recovered. A better solution is to use a closed retort.
There are many kinds of mercury retorts. All of them require strong, directed heat. A blowtorch or a fire with an air blower will help to recover all the gold as quickly as possible.
How to make a bowl-style retort
the enamel bowl before heating
the enamel bowl to heat the amalgam
How to make a galvanized pipe retort
This retort is made from standard pipes and plumbing connections. Wear gloves, glasses, and a mask when using it.
- Form gold amalgam into little balls. Always wear gloves (or plastic bags) on your hands while doing this. Put the little balls into the pipe cap.
- Screw the retort together tightly so that no mercury escapes.
- Put the body of the retort into a bed of hot coals, with the bent pipe in a glass or bowl of cool water. This retort works best if it is heated evenly.
- The mercury will escape through the pipe into water. The water will prevent mercury fumes from releasing into the air, and will cool down the mercury so it becomes liquid again.
- When no more mercury is collecting in the water, all the gold has been extracted and all the mercury has been recovered. Tap the pipe to make sure all the mercury falls into the water.
Let the retort cool, and then open it. Pure gold is left behind in the pipe cap.
One problem with this retort is mercury may stick to the inside the first several times it is used. Be patient, and do not touch the mercury. Over time, all the mercury will come out.
Another problem is the gold may stick in the bottom of the retort. To avoid this problem, unscrew the bottom piece before using the retort and hold it upside down over a lit candle until it is coated black. The grease from the candle will prevent gold from sticking.
Uranium is a metal that releases harmful radiation. Radiation causes cancer, skin diseases, and other serious health problems. People are exposed to uranium through mining it, processing it, or living near uranium mines or waste dumps.
Uranium is used to make 2 things: nuclear weapons and nuclear energy. Both are costly, dangerous, and not needed. No country can trust its leaders or military with nuclear weapons built to kill huge numbers of people. What we need is peace.
Nuclear energy is also dangerous, and accidents in nuclear power plants can kill thousands of people. The waste from nuclear energy remains very harmful for thousands of years and cannot be disposed of safely. Electricity can be made in safer ways.