Safe and Effective Gold Purification Methods Without Mercury
Is it possible to purify gold without using mercury? Absolutely, and there are several methods available that are both effective and safer for both the environment and those involved in the process. This article will explore the various methods used, including nonchemical ones, as well as the risks associated with using mercury in gold purification.
The Risks of Mercury in Gold Purification
Mercury, while once a common method for gold purification due to its ability to dissolve gold at room temperature, has become largely obsolete in modern gold mining and purification operations. This is not only due to its high cost and the dangers it poses to human health but also because it can have devastating effects on ecosystems, particularly when it settles in mud flats and becomes the foundation of organomercury compounds, which are highly toxic.
Although some smaller, non-commercial operations still use mercury, the consensus among large-scale commercial operations is that it has been abandoned. Mercury is a known neurotoxin that can penetrate the body, and its accumulation can lead to significant health issues.
Alternative Methods to Mercury for Gold Purification
There are several other methods that can be used to purify gold without the use of mercury. These methods fall into two broad categories: nonchemical and chemical.
Nonchemical Methods
Nonchemical methods for gold purification include gravity concentrators, shaker tables, and bioindustrial plants.
Gravity Concentrators: These devices work by using a combination of gravity and mechanical forces to separate gold from other materials. They are particularly useful in areas with more complex gold ores that contain other valuable minerals.
Shaker Tables: Shaker tables are a more labor-intensive alternative to gravity concentrators. They involve placing gold-bearing material on to a vibrating shaker table, which sorts the materials based on their density. The gold then accumulates in a pile of rich material that can be manually collected.
Bioindustrial Plants: These are industrial facilities that utilize biological processes to leach gold from crushed rock. This method is particularly useful when the gold is found in hard rock, as it allows for the selective extraction of gold from the rock matrix without the need for extensive mechanical processing.
Chemical Methods
Chemical methods for gold purification can be safer and more efficient, especially when combined with nonchemical methods. The primary chemical used is potassium cyanide (KCN), which is highly toxic but can be handled safely when proper safety measures are in place.
KCN works by chemically dissolving the gold from the ore, which is then precipitated out as gold metal. It is important to note that while KCN is effective, it must be used with caution to prevent environmental contamination and ensure worker safety. Proper ventilation, respirators, and gloves are essential when handling this chemical.
Other Methods for Gold Purification
There are also other methods for purifying gold that do not involve mercury or cyanide, including:
Electrolytic Refining: This method uses electricity to separate gold from other metals in the ore. It is a safer and more controlled process, but it requires specialized equipment and expertise.
Gold Refining Kits: Commercially available gold refining kits can be used by individuals to purify gold. These kits are designed to be user-friendly and include all necessary chemicals and equipment.
It is important to choose the right method for your specific needs and resources. The process of purifying gold can be complex, but with the right knowledge and equipment, it can be done effectively and safely without the use of toxic chemicals.
Conclusion
While mercury was once a common method for gold purification, modern practices favor safer, more environmentally friendly alternatives. Whether using gravity concentrators, shaker tables, bioindustrial plants, or chemical methods such as potassium cyanide or electrolytic refining, there are many options available. The key is to choose the method that best suits your resources and to prioritize safety and environmental considerations.