How to make and use a simple retort for separating gold-mercury
Mercury is used in amalgamation to recover gold in its native or 'free' form. While mercury
simplifies the process greatly, it must be remem bered that it is a very dangerous substance,
especially when inhaled or absorbed through the skin.
Mercury is an 'accum ulative' poison, meaning that repeated exposure, even of very small
amounts, can build up in the body, leading eventually to mercury poisoning.
Mercury released into the atmosphere is also dangerous because it combines easily with other
substances (such as hydrocarbons) to form com pounds which can easily be taken up by other
organisms, such as fish and shellfish. A build-up of m ercury in these organisms can make them
dangerous to eat.
Signs of serious mercury poisoning include stomach pains, vomiting, headache s, shaking,
collapse, diarrhoea and, occasionally, cardiac weakness. Indications of low-Ievel poisoning
include nervousness, depression, vague fea rs, sleeping difficulties, reduced vision and poor
co-ordination of the limbs.
The need for a closed retort
Because of these dangers, it is very important to handle mercury extremely carefully. When
working with gold am algam, the mercury should be distilled in a closed retort. This not only
ensures the health of those involved and protects the environment, but the mercury can also
be recovered for future use.
Figure 1: A simple retort
Discharge end
A glass of water
Oxy-acetylene torch
Charcoal fire