What is a good Fire Assay or Smelting/Melting Gold Book?


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Hello All,

Looking for recommendations on any good books, publications or websites on conducting your own fire assay's and melting/smelting your own gold? I know there are many out there, but what are the better ones if you're looking to do it yourself?

I know Chris Ralph wrote a pretty good article in the ICMJ this month about it. I've read it several times.

Thanks for any suggestions in advance.

Rob Allison

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Hey Chris,

Well I would like at some point in time to pick up a nice furnance and equipment need to melt down fine gold, mostly from crushed ore and smaller placer gold. So for just melting gold, what would you recommend as far as books if any and all equipmented needed including safety PPE?

The other portion is the Fire Assay. I'm always sending off ore from my own claims and other places I have stumbled onto to see what the AU and AG content is. Many have said instead of sending in ore to have someone do the test (such as a Lab), they are simple and can be performed from home if you have the equipment. I know there are also a handful of books on Assaying.

Most of the veins I have been sampling have been a real consistant .25 - .65 OPT AU and ranging from .25 - 3.5 OPT AG. I have recently send off some sample of average, run of the mill ore and it has returned ranging from .65 - 1.1 OPT AU. I'm having a local Lab in Arizona do these tests, so I know the results are pretty dead on.

Any help would be appreciated.

Rob Allison

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Rob, Like ron says a lot of the older ones have great info, I have one called Fire Assaying , from 1907 and is pretty good. Also youtube has some good ones.

Dave

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Hey Rob,

My brother and I are just starting to get into that ourselves. From what we've learned so far, which is very little I might add..., you can assemble a relatively cheap assaying kit yourself. Found a guy near us, Phoenix, who showed briefly how to do it, and recommended this book, "Recovery And Refining Of Precious Metals by C.W. Ammen", to guide us through it. Amazon and Barnes & Noble have it for about $175. Also, there are two versions, 1984 and 1997. Try to get later one if possible. At least for us, the book gets pretty technical in certain areas, but is pretty much spot on for the home assayer. He even showed us how to do on site assays using a blow torch, which can be done in about 30 minutes, right at the mine. The book is a little expensive, but the knowledge contained is astounding. Hope this helps.

Steve

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The melting part is not too difficult. There are electric furnaces for less than $1000 you can buy and mix in some simple fluxes like borax and sodium carbonate (essentially the same as bicarbonate). No big deal to pour your own small bars and there are folks out there in the prospecting community that carry that kind of stuff for sale (some advertise in the ICMJ Prospecting and Mining Journal).

Home assaying is a lot more tricky. There is a real art to it and it takes a lot more understanding of chemistry to do it right. It is also much more expensive to set yourself up do it right - you need accurate scales, a number of different chemicals and other equipment. If you are doing the assays for your own mining, then perhaps home made assays are OK. If you are planning to sell or lease the property, any exploration company will consider your home made assays worthless. Commercial assays by a real lab are much more credible. If someone tells you you can do good assays without a scale or furnace using a blow torch, optical bead size measurement and other non-standard methods, its pure BS. Those assays are much, much less accurate than normal methods - they are real rough and dirty ballpark estimates at best. if accuracy is unimportant and rough and dirty ballpark is all you need, then the cheapie methods may be OK if your never need to get a mining company to believe them. I regularly get questions from guys about - "I did my blow torch assays and then checked them and the results dont make sense, or I did this wet chemical alternative assay and it didnt come out right - what did I do wrong? The reality is that there are so many possible problems, you need a chemical engineer to be standing next to you during the whole process to figure out all the possible things that might go wrong. The only folks who say that the cheapie home assays are just as good as a real fire assays are the salesmen of such cheapie set ups.

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Rob

Chris Ralph is absolutely correct here. I learned some very basics on assaying from Don Robinson who is a professional assayer and it is a complicated system to get accurate results. One of things that you have to know is the make up of the ore that is being tested because that determines the make up of the flux.

Its a lot of fun if you have the correct equipment, good luck with it.

Wes

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Rob you can also pick up relatively inexpensive front loading ceramic kilns with a thermocouple from ceramic supplies. These are used by ceramic potters, but you can easily use them for pouring your own bars. As a cheap alternative to the thermocouples, pyrometric cones can be used for monitoring temperatures and times. As Chris said I'd probably stick with commericial/professional analysis for any ore/rock grab samples. You'll probably want to know if there are any other refractile components which for example might prevent any downstream leaching operations, if you're thinking of going that way.

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Sorry for the confusion. I never intended to imply that a home assay is anywhere close to a professional assay. We have our ore assayed at Copper State in Prescott AZ. What we do with our home kit is to get a "simple" qualitive bead which is examined through a portable or digital microscope on site. There are further steps involved, but that's the basic idea. This lets us know, "roughly", the compositions of different streaks in the mine. It is not accurate, but if you know what to look for, you have a better understanding of how to approach that particular sample. And yes, the gentleman with whom we are in touch with is in fact a chemical and mining engineer. He has devised his own flux, to better deal with sulfides, tellurides, etc. Again, it is a "poor man's test", but if you can at least create a "bead" with the process, you're on the right track. As said, if you are looking for a "real difinitive" assay, you must send your samples out to a professional. We have already done this, and use our simple method to "follow the streak" so to speak. It can get quite expensive to have many samples assayed, usually $50-$75 per basic assay, and the costs increase depending on what you want. Our samples were taken from all over the mine, which we pulverized ourselves. We had a six pound bag of 200 mesh, which the assayers use about a teaspoon of for the assay. Results were .08 AU, .15 AG. We also have a geologist, who used to work with mining companies, that wants to come along with us on our next outing, and show us what the heck we're looking for, as we have no idea...lol. We are just two simple guys, brothers with sons, who are in the mine with pick ax, shovels and lights. We've literally just started and are doing this just for fun and hobby. If it starts to pay-off, we will certainly take it to the next level. Regardless of what you are doing, the book itself, "Recovery And Refining Of Precious Metals" is considered by most to be one of, if not, the best information out there.

Steve

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