Inovative concept

[arizau]

Free up the gold from gangue material and increase the broadest dimensions of the liberated gold and other gold contained in the concentrates by flattening it, then reclassify the concentrates through the same fine screen that it had initially passed and smaller sizes too, concentrate the various screen fractions and recover the gold. This is not my idea as I found this article on another forum and thought I would share it. Yukon College: Yukon innovation increases gold recovery for placer miners
Rod mills have long been used to grind ore in hard rock processing prior to flotation, etc. recovery but his method for otherwise hard to deal with placer concentrates is new and a neat concept.

 

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[goldenIrishman]

I've noticed that when I crush my black sands that the gold has a tendency to flatten out. When it does that it makes it easier to see due to the increase in surface area. Guess it's a good thing that gold is so mailable compared to the materials we find it in.

 

[arizau]

More info.
New gizmo could help placer miners snag lost gold | Yukon News

 

[azblackbird]

Great idea! Not only do you get the rolling action (aka ball mill) from the rods, but also the up and down pounding action from a stamp mill.

 

[arizau]

I did a little research and found a formal presentation outline for this concept. http://www.geology.gov.yk.ca/pdf/141114_Nov1014_Grinding_for_Gold_Presentation.pdf
Pretty fully explains the basics if one were of a mind to build one.

 

[Bonaro]

yeah but.....if you make the gold too flat it will tend to float.

 

[Bill_saf]

I take it you didn't read the pdf in post#5 that ARizau put up. I took a good look and Randy Clarkson has made some really go points on rod mills.

 

[arizau]

Here are a couple of posts from Goldprospectingforum.com (Goldhog's forum) of an actual user of this system. Since mostly only gold is caught at the various stages of screening no further panning is required.

CdnSilverback
Post subject: Re: clarifying micro gold
We made a bar mill using an old electric cement mixer. After the cons have been run on the table. we collect the blacks. Once the season is over, we run the collected blacks at a rate of about 2 pounds to an equal amount of water for about 7 minutes. Th gold "flattens out" and anything else powders down. We then run this through a series of screens... down to 400 sometimes... the gold is then caught by the screens. Works well for us!

CdnSilverback
Post subject: Re: clarifying micro gold
We started with a 8" inside diameter, 1/2" steel pipe. Welded a plate at one end and then welded a connector to that plate for the cement mixer shaft. The top end we put a plate with a half turn lock on it as a cover. The rods inside are varying sizes... 3/8", 1/2", 5/8" and 3/4"... each about 1/2" shorter than the inside of the mill so that they can not jam while turning.

We place about 2 pounds of black sand collected from the vibrating table along with about 2 cups of water in the mill and run the unit for about 7 minutes. This slurry is then poured through a 100 screen. The "flattened" gold stays on the screen. What goes through the screen is collected.

This collected material is put back into the mill and run for 3 minutes. Again, this milled material is then screened through a 200 screen to collect the gold.

This is done over again a third time... using a 300 screen.. then a 400... and if you like... even smaller screens.

The principle of the whole operation is that the hard materials will mill to smaller and smaller sizing... while the gold will "spread" due to its malleability. This spreading is what makes it larger than the screen being used... thereby being rescued from the sands.

We even get sands from the local gold shack that cleans other people's gold.

We seem to average about 1.5 grams per 2 pound run through.
Gavin and I talked a lot about this at the Geoconference in Whitehorse. From what I gather, there are a lot of those being made this year up here!

From these references and from the articles then I like this system much better than a blue bowl or miller table! I don't think my usual gold production would justify the expense though.

 

[azblackbird]

This should be required viewing for anybody that is engaged in the business of mining. In reference to the subject matter of this thread, pay particular attention at the 16:00 minute mark on this video detailing the use of rod mills, and the fineness in which they can further pulverize the gold ore. This is somewhat of a long video, but it is very well worth watching!

 

[ikesdad]

I worked at the Homestake in the 70s. Much modernizing had been done since the video was made.

 

[KevinInColorado]

Great video, thanks for sharing!