Torch Assaying

[Socorro]

Hi Folks,

I have been curious as to how many of you know of and use Torch Assaying? I trained under the late Charles Butler and have not seen hardly any indications, at least in public areas of people performing their own torch assays. It has been the most valuable asset in my bag of prospecting tools that I have to date and just wondering who else is using this invaluable process.

Happy Prospecting,

Dwight

 

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[IMAUDIGGER]

Welcome. Can you describe your process?

 

[Socorro]

Welcome. Can you describe your process?

A little late getting back to the forum, making gold has been getting in my way past couple of days.

A Torch Assay is simply a process in which you use an Oxyacetylene torch to perform an Assay for noble metals rather than a standard Fire Assay. It has several benefits and advantages from a standard Fire Assay, one being that it provides you very accurate results in 15 minutes or less. It also allows you the flexibility to manipulate your torch settings from a reductive to an oxidizing flame to compensate on the "fly" with difficult ores, without the long and arduous trial & error testing that you have to do in a standard Fire Assay.

The Torch Assay is designed to be used in conjunction with a standard Fire Assay for when you need an accurate analysis of your noble metals. However, if you are looking to determine the values expeditiously or needing to determine loss values, say at the end of your process recovery equipment, it provides quick and accurate results in minutes rather than hours, days or weeks.

I have located some very large gold deposits simply by using the Torch Assay method on-site. I've just been kind of curious about how many were using this process or may have had heard of it.
I added a picture of the gold that is contained within the ore body we are mining. As you can see from the picture, the individual lines are .001 thousands of an inch, about 1/6 the width of a human hair. This is gold in the 800-1000 mesh range. This is where Torch Assaying really comes in handy when initial gold evaluation and as well as determining potential losses through your gold recovery equipment in the exiting gangue.

 

[arizau]

Nope, I've never heard of it. It must be a process mostly only known to professionals such as Assayers, Metallurgists, Geologists, and maybe Mining Engineers and the like. Is this the process? https://www.goldprospectorsoftherockies.com/articles/assaying_torch_fire_assaying_technique.htm. I suppose a prospector could at least use the process to some extent to produce a button just to verify that the sample contains any gold, even if microscopic, but would still need someone else to determine the percentage/OPT assuming he does not have the other equipment (scales, etc.) to do that himself.

What separation process did you use to concentrate the native, I assume, micro-gold shown in the picture?

 

[605dano]

Here is a link for an article on torch assays. I have a friend who used to do them for me. They worked well but the sample size was small, so if there was variation in your ore the results could be skewed. But for a quick on the spot assay they worked well.
https://www.goldprospectorsoftherockies.com/articles/assaying_torch_fire_assaying_technique.htm

 

[Socorro]

One of the biggest benefits of utilizing the Torch Assay process is that you are measuring the bead solely based upon a volumetric measurement rather than by weight. With a bead, say of normal size of a standard assay, the accuracy is actually extremely accurate. Obviously, as the bead (gold) gets bigger, you have a "squatting" effect of the bead that becomes more and more problematic, but even for extremely high OPT assay is surprisingly accurate. Not having to have the extremely expensive scales for weighing a small bead makes it much more accessible for the smaller miner or prospector. Any ore bodies that I have determined have values, I run both the Fire and Torch Assay together. As a rule, they are very accurate results running together.

The only issues one may run across is that the Torch assay will actually provide a more accurate results as to the true amount of nobel elements in your sample, whereas the fire assay will fluctuate based upon the grind of the ore being sampled and the specific blend and makeup of your flux, which depending upon your specific ore, can have a huge effect on your assays, such as high amounts of copper or other contaminating metals present.

The picture of the 800-1000 Mesh gold was recovered with my own 3-Dimensional gravity separation table. Typically, anything over 500 mesh with gravity separation is very difficult to do in a production process with normal recovery equipment. With regards to "Micro-gold", everyone seems to have a different interpretation of the phrase, but being a machinist, I typically consider anything below .001" of an inch to be in the "Micro-Gold" category, however, others mileage may vary.

 

[Socorro]

Nope, I've never heard of it. It must be a process mostly only known to professionals such as Assayers, Metallurgists, Geologists, and maybe Mining Engineers and the like. Is this the process? https://www.goldprospectorsoftherockies.com/articles/assaying_torch_fire_assaying_technique.htm. I suppose a prospector could at least use the process to some extent to produce a button just to verify that the sample contains any gold, even if microscopic, but would still need someone else to determine the percentage/OPT assuming he does not have the other equipment (scales, etc.) to do that himself.

What separation process did you use to concentrate the native, I assume, micro-gold shown in the picture?

I meant to reply directly but mistyped. ;-) I think I answered your question in my general response though. I do know that the late Mr. Butler had taught a few folks outside of the country, specifically large mining companies, but don't ever seem to run across anybody here in the U.S that gets into the process.