How is Gold Refined?
Gold refining is a fascinating process that transforms raw, mined gold into the pure, gleaming metal we know. It's a vital step for those looking to ensure the value and purity of their investment.
But how exactly is gold refined? This guide will walk you through the traditional and modern methods of gold refining, giving you a comprehensive understanding of how raw gold becomes the high-quality gold bars and coins that investors prize.
What is Gold Refining?
Gold refining is the process of removing impurities from raw gold to achieve a higher level of purity. When gold is mined, it often comes mixed with other metals like silver, copper, or zinc.
Refining is what makes gold usable in jewellery and electronics. Without this process, gold would remain in its impure, often unmarketable, form. Refining helps separate the gold from other elements, ensuring its purity and, consequently, its value. For investors, buying gold is more reliable, easier to trade, and typically fetches a higher price due to its guaranteed quality.
Methods of Gold Refining
There are several methods used to refine gold, ranging from ancient techniques to more advanced modern methods. These processes vary in complexity and the level of purity they can achieve.
The three most common modern methods are the Aqua Regia process, the Wohlwill process, and the Miller process.
Before we delve into these contemporary methods, let’s have a quick look at some ancient techniques still recognised today for their historical significance.
Ancient Techniques of Refining Gold
Cementation
Cementation was one of the earliest methods of gold refining used by ancient civilisations. It involves heating gold in the presence of salt and brick dust, which causes the impurities to separate and be absorbed by the brick.
Cupellation
Another ancient method is cupellation, used primarily to refine gold or silver mixed with lead. The metal is placed in a porous, cup-shaped furnace and heated to a high temperature. The lead oxidises and is absorbed by the porous container, leaving behind the pure gold.
Modern Techniques for Refining Gold
Modern refining processes can achieve purity levels that ancient techniques couldn't, making them far more reliable and efficient for today’s investors. Let’s explore three of the most widely used modern methods:
Aqua Regia Process
The Aqua Regia process is a chemical technique that involves dissolving gold using a mixture of nitric acid and hydrochloric acid, known as "aqua regia". The term means "royal water" in Latin, named so for its ability to dissolve even noble metals like gold and platinum. In this process, gold is dissolved into a solution, leaving other metals behind. The gold is then precipitated out and purified further if needed.
Wohlwill Process
The Wohlwill process is another method, but this one uses electrolysis to refine gold. Invented by Emil Wohlwill in 1874, this process can produce gold of up to 99.999% purity. In this method, impure gold is cast into an electrode called an anode, and when an electric current is passed through, the gold dissolves and is redeposited onto a cathode as pure gold.
Miller Process
The Miller process is one of the quicker methods for refining gold, although it doesn't quite achieve the same purity levels as the Wohlwill process. In this method, gold is melted, and chlorine gas is blown through the molten metal. The impurities in the gold bond with the chlorine to form chlorides, which can then be skimmed off, leaving behind nearly pure gold.
This method is highly efficient for large-scale operations due to its speed and simplicity, but it typically results in a purity level of about 99.5%. For many investors, this level of purity is more than sufficient, though for those seeking the highest possible purity, additional refinement through other methods may be required.
Benefits of Gold Refining
Refining gold has several key advantages. Firstly, refined gold is far more valuable than raw, unrefined gold because of its purity. The higher the purity, the higher the value. This is especially important for those investing in gold bullion or coins, where guaranteed purity is essential. Secondly, refining also ensures the metal is free of impurities, which can otherwise affect its durability, appearance, and marketability.
The ability to guarantee purity through refining adds trust to transactions. Investors can confidently buy and sell refined gold, knowing its value has been verified. In industries like electronics, highly refined gold is essential for functionality, making the refining process critical to the broader market.
Conclusion
Gold refining is a crucial step in ensuring the value and purity of the gold investors buy. For investors, understanding the refining process helps ensure they’re making smart decisions when purchasing gold, knowing they’re getting a product of guaranteed quality.