We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What Is the Miller Process?

Mary McMahon
By
Updated May 17, 2024
Our promise to you
About Mechanics is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At About Mechanics, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The Miller process is a gold refining process that produces gold of approximately 99.95% purity, sufficient for many applications. It is faster and less costly than other refining options used to produce purer gold, which makes it a popular choice at some refineries. This technique involves passing chlorine gas through molten told to trigger a chemical reaction that separates impurities. If a refinery needs gold of a higher purity, it can send the processed bullion to a facility with other refining techniques available for additional treatment.

Refinery starts with basic smelting to extract gold and remove as many impurities as possible. Smelted gold can be poured into a crucible where it is kept hot while chlorine gas bubbles through it. The gas reacts with impurities, causing them to precipitate to the surface in the form of chlorides which can be skimmed away. Some also form gases that vent from the top of the crucible.

After approximately an hour and a half, the gold is pure enough that it can be poured into solid bullion or other storage formats. Gold treated with the Miller process is assayed to confirm the purity so the final product can be stamped to record it. For industrial processes like gold contacts on electrical equipment, gold of 99.95% purity is often acceptable. Using gold produced by Miller process can be less expensive than 99.99% gold mixtures, which require more time and money.

Environmental controls can be important during gold processing. Mining to smelting and final purification can generate a number of harmful chemicals that need to be controlled. Techniques for managing the environmental impact of gold production can include filtering industrial waste, storing chemicals in hazardous material containers for disposal, and making refinery processes more efficient to reduce overall waste and usage. Firms using the Miller process may control their chlorine to prevent environmental contamination and worker injury while also limiting waste, because chlorine can get expensive when used on an industrial scale.

Markets where gold is traded typically have strict regulations on the content and weight of gold products. This ensures consistency and prevents attempts to take advantage of traders and consumers with products that may not contain pure gold or could be underweight. Bullion can be randomly assayed and weighed to confirm that it meets the advertised specifications. Substitution of Miller process gold for other golds with a higher purity rate can be grounds for penalties.

About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a About Mechanics researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Discussion Comments
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

Learn more
About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.

About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.