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How do I refine precious metal?
An overview on how to refine precious metals
There are many kinds of materials that yield pure gold, platinum, or silver when refined. Though it's usually a little intimidating the first time you do anything, refining precious metals yourself is relatively easy to do (even with no experience) provided you have the right information, supplies, and equipment.
This article contains very brief information on the most popular methods of refining precious metals. Be sure to check out some of our expanded articles for more information. You can also ask us for refining help and advice by calling 1-800-295-6320 or writing to us at firstname.lastname@example.org (at no charge, of course).
What kinds of materials can you refine yourself?
A very popular and lucrative refining asset (we even designed a machine for this). This includes circuit boards, including CPUs, RAM, pins, and other computer components.
Jewelry, Coins, Bullion
Loose PMs or PM-plated items such as old coins, necklaces, bars, and alike.
An excellent source of platinum group metals, such as palladium and rhodium.
Gold Nuggets and Black Sand
This one's pretty obvious :-).
Grindings, bench sweeps, polishing sweeps, floor sweeps, etc.
X-ray film has silver in it and is often purchased and collected just for its silver content.
The advantage of refining yourself vs. selling your precious items to a refining company
We love working with other refiners; it's our lives' passion. So one of the hardest things for us is when new refiners recount horror stories of being cheated out of the true value of their PMs by unscrupulous refining companies. It hits home for us, and we hear it all too often.
Many refining companies are honest. But too many others are quick take advantage of customers by paying rates 8-10 times lower than what they could have gotten had they refined it themselves. Many don't realize that, given the right tools, refining precious metals can be done in your own home, usually saving hundreds and often thousands of dollars (and frustration). And this frustrating fact is why our small team has spent the past three decades perfecting refining for home use.
Gold and Platinum
There are two methods: working with saltwater and working with acid. Both work equally as well, but for a variety of reasons, including safety, cost and the kind of material that you are refining, you may choose to use one method over the other.
There are two methods: chemical and electrolytic processes. If you're refining purely chemically, you will have to use dilute nitric acid. Sorry, no way around that. However, if you choose to refine using the electrolytic way, then the nitric acid will be diluted, resulting in relatively little fumes.
This process is excellent for silver and platinum group metals. Silver is recoverable using this process, but unfortunately, it will not refine the silver.
We perfected this process back in the late 80s for other refiners to refine both gold and platinum group metals safely, while also reducing costs. After working with people who have refined using this method, we've carefully perfected this method through the Simplicity Refining System to make it simple for individuals and companies. We're overjoyed that thousands of happy refiners have saved millions of dollars using this perfected process.
Refining Gold (Saltwater)
The process for the Simplicity method is simple:
Hang your metal on a wire that is connected to a car battery charger and then immerse the metal in saltwater in the Simplicity (or similar) unit.
Turn on your battery charger. An electric current will run through the metal causing it to dissolve at a rate of about 1 ounce per hour.
Once all of the metal is dissolved, add a selective precipitant, such as Quadratic, to the solution. Only pure gold will turn back into solid metal. For all of the other metals, the impurities will remain dissolved. The resulting gold is at least 99.95% pure gold.
The losses of gold left dissolved in the solution will be less than 4 parts of gold per million parts of saltwater.
Refining Platinum (Saltwater)
The platinum group metals (or PGMs) include: platinum, palladium, rhodium, iridium, osmium, and ruthenium. Platinum, palladium, and rhodium are commonly used in industry and jewelry.
The saltwater process will recover and refine all of the platinum metals and will separate each platinum group metal from the other and will yield a purity of at least 99.95+% purity (99.99% purity is common).
At the present time, this is the only known method of refining mixed PGMs easily, the only known method of consistently achieving this degree of purity, and the only known method of refining PGMs with a minimum of hazard.
Melt your metal with a base metal, such as tin or ASR Alloy and pour into an ingot mold to make a bar.
Hang it on a wire in the Simplicity Refining System (or similar) and connect the other end of the wire to a battery charger.
Turn on your battery charger. The base metal in the ingot will start to dissolve and the platinum group metals will convert into platinum group chlorides.
Once the ingot finishes disintegrating (which takes about one hour per ounce) use water to rinse the platinum group chloride you made.
Dissolve them in ammonia and add a selective precipitant for platinum group metals. Each platinum group metal will precipitant in a different time frame, with about 1/2 hour between the conclusion of each precipitation from the start of the next.
By simply recovering the precipitated metal between each precipitation, you can achieve a purity of at least 99.95+ purity for each platinum group metal.
Learn more about saltwater refining supplies
Refining gold with acid
The traditional method called aqua regia (Latin for "Royal Water") dates back hundreds of years. This method requires the use of both nitric and hydrochloric acids. Due to the corrosive nature of nitric acid, the fumes produced by this process (nitric oxides) are very harmful. Nitric acid fumes will rust high grade stainless steel in less than 1 second of exposure.
To correct this issue, we've developed a non-corrosive, pelletized substitute for nitric acid called MX3 Concentrate. While there are still fumes when using MX3 alone, they are limited to ordinary muriatic acid (a chemical available in most paint and hardware stores) fumes. We've also developed self-contained machine for people who prefer this method: the Shor Aqua Regia Refining System. It is a sealed unit with an integrated scrubbing system to even eliminate the remaining muriatic acid fumes. It also scrubs the fumes if you want to work with nitric acid based aqua regia.
Motivation for using acid instead of saltwater
There are two main motivations for using aqua regia instead of saltwater:
Some materials, such as circuit boards and jeweler's polishing sweeps, are much more easily refined using the process, as it is easier to reduce gold loss from decanting (depending on your precipitant).
You may want to refine out of doors, where there is plenty of ventilation. You can set up your own system, using the Aqua Regia Starter Package and a few other things, such as buckets and beakers, for less than $100.
Refining Gold (Aqua Regia)
The aqua regia method works regardless of whether you're using nitric acid based aqua regia or MX3-based aqua regia. Like the Simplicity process, aqua regia is relatively simple:
Dissolved in the aqua regia using your selected dissolving agent.
Once all of the metal is dissolved, add urea (a harmless chemical: CO(NH2)2) to remove any free nitrogen in solution.
With nitric-acid based aqua regia, a large amount of urea is generally required.
With MX3 based aqua regia, usually only a pinch is required.
The purpose of the urea is to prevent gold from re-dissolving after it has been precipitated. If urea is not added and some free nitrogen remains dissolved in solution, some gold may be re-dissolved.
Add your selective precipitant to your solution. The gold will be selectively precipitated out of solution.
There are a variety of precipitants that can be used: Quadratic, sodium metabisulfite, sulfur dioxide gas, Storm Precipitant and ferrous sulfate are among the most common. Most of these precipitants produce very unpleasant fumes or odors and have other negative side effects. Some people prefer Quadratic Precipitant, since it's odorless, fumeless, produces large particles that are easily rinsed, and has an unlimited shelf life.
Regardless of the precipitant used however, the resulting gold is typically at least 99.95% pure.
Check your solution is checked with gold detection liquid to ensure that there are no precious metal losses. The gold detection test is sensitive to around 4 parts of gold per million parts of solution--the maximum loss of metal left dissolved in solution.
Refining Platinum (Aqua Regia)
When platinum group metals are mixed, it is very complicated and difficult to refine them using aqua regia. However, when they are not mixed, the aqua regia method is not hard. The procedure is very similar to refining gold in aqua regia, but the precipitant used will be different. There are several standard precipitants, different precipitants for different platinum group metals. Refining by this method is tricky and the purity of the resultant platinum group metal is often below normal standards. Refining of platinum metals is best done by the saltwater method.
See what Aqua Regia has to offer
The chemical process requires no equipment, just a few buckets. Though this process is not hard to master, the fumes are quite corrosive.
Dissolve the silver in nitric acid.
Once the silver is dissolved, precipitate it out of solution by adding ordinary table salt. Adding salt precipitates silver chloride.
Add sodium hydroxide (also known as 'caustic soda' or 'lye') to the solution. This causes the white silver chloride to oxidize. This blackens it and turns it into silver oxide.
Add sugar water, which will turn the silver oxide into pure silver.
A simpler process of refining silver is electrolytic.
Hang your silver in an electrolytic bag and immerse it into a very diluted nitric acid solution.
The silver is connected to a "rectifier," which supplies a highly-filtered DC current.
The silver dissolves and the impurities fall into the electrolytic bag.
Simultaneously, the pure silver plates out onto a cathode in other electrolytic bag in solution.
This simple process can run 24 hours a day, 7 days a week, with minimal fumes. Electrolytic silver refining requires a starting purity of at least 92% for sterling silver.
How do these methods compare?
|Method||Speed||Materials typically refined||Fumes||Ease of use||Costs||Comments|
|Gold Refining with Nitric-acid-based Aqua Regia||1-2 hours per batch||e-scrap, jewelry, black sands, jewelers sweeps||very highly corrosive||simple||setup costs can be as low as $100, depending upon capacity and sophisitication about $1-$2 per ounce to operate||silver content can slow the process significantly|
|Gold Refining with SubZero-based Aqua Regia||1-2 hours per batch||e-scrap, jewelry, black sands, jewelers sweeps||corrosive||simple||setup costs can be as low as $100, depending upon capacity and sophisitication||silver content can slow the process significantly|
|Gold Refining with Saltwater||1 hour per ounce of scrap||jewelry, gold bars or ingots||very mildly corrosive (saltwater)||simple||about $600 to set up. About $1-$2 per ounce to operate||silver content above 6% can slow the process|
|Platinum Refining with Nitric-acid-based Aqua Regia||varies||catalytic converters, e-scrap, jewelry||very, very highly corrosive||very complicated||varies widely depending upon the metal content||the acid has to be boiled to dissolve the platinum|
|Platinum Refining with SubZero-based Aqua Regia||varies||catalytic converters, e-scrap, jewelry||very corrosive||very complicated||varies widely depending upon the metal content||the acid has to be boiled to dissolve the platinum|
|Platinum Refining with Saltwater||about 1-2 hours per ounce||jewelry, bars or ingots||very mildly corrosive||simple||About $600 to set up. About $5 per ounce to operate||when working with catalytic converters, the PGM's are usually recovered first by heating the converters first in a solution of lye and water (dissolving the ceramic)|
|Silver Refining in Nitric Acid||about 3-4 hours per batch||jewelry, silverware, x-ray film, etc.||very highly corrosive||simple||consumable costs about $1 per ounce||almost no setup costs if done outdoors|
|Silver Refining by Electrolytic Method||about 1 hour per ounce||jewelry, silverware, ingots (bars)||somewhat corrosive||very simple||about $500; consumable cost of a few dollars per day||requires a starting purity of at least 93% (sterling silver)|
When in doubt, ask us for help!
When following the right procedures and with the right supplies, it's normal to get a purity of 99.95%+ with no gold material lost.
If you need advice or help with your setup, we're here to help (even if you don't buy anything from us). Check out our online help library. It's the way we help people and the way we've helped amateur and professional refiners, and how Shor has done business for nearly a century. Call us at 1-800-295-6320 or write to us at email@example.com.