The safest way is always to do it in a self-contained, sealed system that scrubs fumes. However, no matter what chemicals or procedure you chose, there are some safety gear you must use:
If refining in-doors, a complete, sealed, refining system, with a fume scrubber, is strongly recommended. Even when working with environmentally-safe materials, such as MX3 Dissolving Agent or Quadratic Precipitant, you still must use muriatic (another name for hydrochloric) acid. The acid fumes need to be contained to prevent corrosion of your tools (and your lungs). So a sealed system with a built in fume scrubber is essential. If you’re working outdoors, you can use ordinary buckets and beakers.
What environment works best for me?
Which chemicals and which equipment you choose will define the potential hazards in the refining procedure. We built a questionnaire-guide for choosing the supplies and equipment that fit your needs.
You'll need some sort of Dissolving Agent for dissolving your metal, as well as a Precipitating Agent for precipitating your particles.
Below are comparison charts for commonly-used dissolving agents and precipitants, comparing and contrasting the pros and cons of each one. These same charts will reappear in the relevant sections of this guidebook.
|Dissolving Agent||Sodium Nitrate||MX3 Concentrate||Nitric Acid|
|Dissolving into HCl||Slow||Instantaneous||Instantaneous|
*heating not required except when dissolving platinum group metals
|Precipitant||Sodium Metabisulfite||Ferrous Sulfate||Quadratic Precipitant|
|Shelf Life||Unlimited||2 to 4 months||Unlimited|
|Requires Heating?||No||No||Heat to 160° F|
|Gold Particle Size||Small||Moderate||Large|
|Gold Particle Color||Light to dark brown||Light to dark brown||Golden brown|
The traditional form of aqua regia is a combination of nitric and hydrochloric acid. Nitric acid is very hazardous. When combined with hydrochloric and metal, it produces prodigious amounts of brown, very corrosive, toxic gases, including nitric oxide. These fumes are so corrosive that they will rust high grade stainless steel with less than 1 second of exposure.
While these instructions will also work for nitric acid, it is dangerous, expensive and difficult to obtain. The dry substitutes, either MX3 or sodium nitrate, are far safer, less expensive and easily obtained.
Seems like a silly thing to ask, but knowing your metal content ahead of time can help you ensure you know how much (and which) supplies you’ll need. Your first step is to know how much gold content you want to refine. To do this, you should get a representative sample of your precious metals. The number doesn’t need to be exact, but should be in the neighborhood of how much metal you have. This is so you don’t start with too few supplies or buy too much.
Once you know how much metal you want to refine, you can determine how much supplies you will need to refine that metal. Knowing the correct amount of chemicals to use will prevent a waste of chemicals and provide you with the most economical use of both the chemicals and your time.
If you’re refining CPUs, Gold Fingers (from RAM, PCI, etc), microprocessors, or other gold-plated electronic scrap, we built a series of handy calculators to estimate how much gold you have. If you already know the weight of the metal you want to refine, go ahead and skip this step.
This is pretty simple. Approximately 2% (source) of the weight of a catalytic converter is the weight of the precious metals included in the unit, which primarily consists of various types of platinum.
If you have stones or other non-metal items in your jewelry, you should either remove them or subtract their weight from the total jewelry weight. Generally you need to remove stones from jewelry before refining it, except if you’re refining using the Simplicity which safely dismounts stones.
For bullion and other gold items, this part is easy. Simply weigh the metal.
Part 2: The Magic Happens — Dissolving Your Gold