My buddy Gary Thomas (a.k.a. "Muskrat") asked that I talk about the use of borax as a gold amalgamation and smelting agent. I suspect very few small-scale miners are aware of this use for borax so Gary's suggestion is a good one.Want to learn more? Read on then.
A Humble Servant
I've spoken on occasion about the dangers of mercury as an amalgamating agent for gold. Once again I want to stress to you mercury is NOT something you want to be using to amalgamate fine gold. It's dangers are well known and its detrimental effects are long lasting both environmentally and from a health physics standpoint. You all know that I place a great deal of faith in the old timers and their prospecting and mining methods, but their use of mercury in the past is...well...nothing short of appalling. Most of those old salts were unaware of mercury's dangers so in this case ignorance could be the plea bargain. After all, they were going for every bit of gold they could recover as should you. It's just that their method in this context was just plain wrong...not from an efficiency context but for the reasons I've already mentioned. Despite all this, mercury continues to be used extensively in small-scale and commercial enterprises in many Third World countries, including some located in Africa, Asia, and Central and South America. However, there is a non-toxic agent that works just as well for binding small particles of gold and enhancing the gold smelting process. That humble servant is borax. Yep, the same borax that goes into Boraxo soap and that used a 20-mule team to commercialize its presence on television back in the 1950s and early 1960s. Experts say the borax method of amalgamation/smelting is actually more efficient than using mercury. This caused me to raise my eyebrows a bit when I first read it, but as I researched this issue at greater length this claim came up time and time again, so there has to be something to it. There's no doubt using borax as an amalgamating agent is much, much safer than using mercury and here's the real kicker...it's a hell of a lot cheaper too!
(Mercury is a big "no-no.")
I'm No Expert
OK, I myself have never used mercury or borax to amalgamate fine gold from concentrates so I can't claim I'm an expert on the use of borax by any stretch of the imagination. What I can do, however, is describe the borax amalgamation process as it's currently used by small-scale gold miners throughout the world, especially in those Third World areas I already mentioned. Here's how they do it:
The miners' moss from small-scale mining equipment (sluice box, dredge, highbanker, etc.) is placed in a bucket or tub of water containing borax. Just how much borax to use is open to debate, but suffice it to say the water and borax mixture should have the same appearance as whole milk when it's poured into a glass. In other words, milky white. The miner's moss or matting is then washed in the bucket or tub just as you would normally do it to free the gold and heavies.
Cheap, Cheap, Cheap
As far as the borax is concerned, the best type to use is commercial grade which comes in sealed packages ranging from a few pounds (usually five) on up to 50 pounds or more. However, you can use good ol' 20-Mule Team Boraxo soap if push comes to shove. A five-pound bag of commercial borax costs around eight-to-10 dollars (USD) while a 50-pound quantity runs around 30 bucks. I don't know how much a five-pound box of Boraxo soap costs, but I hazard a guess it's probably three-to-five dollars...or somewhere in that range.
In Third World locales the concentrates are then run through a mini-sluice and reduced and "refined" (i.e., cleaned). The concentrate residue is then placed in a small plastic container (plastic sandwich bags seem to be the choice in the Third World) and a small amount of water and borax are added. Or, alternately, the concentrates are placed in a gold pan or batea and a bit of water and borax are added to the mix and the whole concoction is stirred around.
(Here's that "milky" color I mentioned.)
What the Experts Say
If you're using a spiral gold wheel or Blue Bowl concentrator to process your heavy concentrates or any piece of fine gold recovery gear that re-circulates water, make sure you have that "milky" color going for you. Again, that's the result of adding borax to the water. Third World miners then take the final result of their borax amalgamation process, let it dry out, and then place it in a clay or ceramic bowl where they apply a hand-held propane torch to it. Gold melts around 1,948 degrees Fahrenheit, but the addition of borax to concentrates actually lowers the gold melting point down some and helps refine impurities out. That's what the experts say, anyway. The end result? A small button of gold.
I have no idea whatsoever of the chemical basis for borax as an amalgamation/refining method. I do know that soap helps in fine gold recovery from a suspension angle. I'm an educated and sometimes smart guy, but if you're interested in how borax works its magic you're on your own. A bit of research on your part should explain all and then you can educate the rest of us! What can be said here is that borax is a hell of a lot cheaper than mercury and essentially safe as far as people and the environment are concerned.
Anyhoo, I hope I've answered "Muskrat's" basic question about borax in fine gold recovery and additionally your own.
Be safe out there.
(c) Jim Rocha (2016)
Questions? E-mail me at email@example.com