ROD MILL DESIGN?!?!?!?

[desert-rat]

Going to start a rod mill in the coming few weeks wanting design do's and don'ts. pictures would be great as well as links to anything helpful. im looking to make the drum from 12"-24" and use something like a 1" bar stock for the rods. input please!

 

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[arizau]

If you have not already then read this thread especially the formal presentation etc. by the developer of this particular process. http://www.treasurenet.com/forums/panning-gold/456622-simple-solution-fine-gold-recovery.html
The design should work for larger material but the run time will probably be longer.

 

[KevinInColorado]

Use a mix of rod diameters. Only run 10-15 minutes before checking your results. Recognize that the point where 3/4 of the material is crushed to a fine powder is enough. The remaining larger pieces are hard to crush because they don't have any gold in them!

 

[Mad Machinist]

The only problem I have with the posted design is the fact that a 75-80% of critical speed, the rods start flying around and without some kind of "sacrificial liner" this mill will wear out rather quickly.

The mills I used to work on had 3" thick manganese steel liners and they would only last six months. Granted they were grinding 80+ tons per hour, 24 hours a day, 7 days a week, but the concept is the same. The only way I could see this design feasible for a small miner is if they were able to obtain the materials to build the drum and the material for the rods at little to no cost. Steel adds up quickly if it constantly needs replaced.

 

[KevinInColorado]

I used a plastic hot cocoa container. It's not showing much wear yet but I can always drink more hot cocoa!

My point: we are not industrial scale so your concerns aren't real problems.

 

[arizau]

Going to start a rod mill in the coming few weeks wanting design do's and don'ts. pictures would be great as well as links to anything helpful. im looking to make the drum from 12"-24" and use something like a 1" bar stock for the rods. input please!

By the way you posed your question and the size(s) you mentioned it appears to me that you are interested in milling some larger sized coarse ore or stones of indiscernible content to be further processed by concentration and ultimately gold separation and recovery. Keeping that in mind; I googled this for you and it has a lot of useful info about rod mills in general concerning their design and operation.
https://www.google.com/webhp?source...pv=2&ie=UTF-8#q=rod mill design and operation
Even if what I surmised is not the case (Maybe you are thinking about gold recovery from already collected concentrates ?) there should still be some info that gives you a better understanding as will some of the previous comments on this thread.

 

[Mad Machinist]

I used a plastic hot cocoa container. It's not showing much wear yet but I can always drink more hot cocoa!

My point: we are not industrial scale so your concerns aren't real problems.

Kevin,

Just take a look at how quickly impact mills wear. ANY time you use carbon steel to bust up rock, it tends to wear rather quickly. I jut want to make sure everyone understands that if your going to take the time to build something, then take the time to do it right in a place where you have all the tools handy. It really sucks trying to repair something at a mine site when you have to improvise because you don't have all the tools you need.

And besides, time spent repairing something in the field is time you are not mining or processing. Even on a small scale, time is money. Most fab shops have a set of rolls there and they can roll a piece of 1/4" AR500 plate as a "liner". It would be sacrificial, help protect the "drum", and be easily replaceable in the field if needed. I know it is an added cost, but like I said, in the field time is money.

I'd rather be mining and processing in the field than fixing something, especially with the promotion at work that severely limits my time in the field now.

 

[desert-rat]

I really like the idea of getting a piece rolled for a liner. I've seen how john deere uses wear plates in equipment and that seems to be a very cost efficient method for this project.

Kevin,

Just take a look at how quickly impact mills wear. ANY time you use carbon steel to bust up rock, it tends to wear rather quickly. I jut want to make sure everyone understands that if your going to take the time to build something, then take the time to do it right in a place where you have all the tools handy. It really sucks trying to repair something at a mine site when you have to improvise because you don't have all the tools you need.

And besides, time spent repairing something in the field is time you are not mining or processing. Even on a small scale, time is money. Most fab shops have a set of rolls there and they can roll a piece of 1/4" AR500 plate as a "liner". It would be sacrificial, help protect the "drum", and be easily replaceable in the field if needed. I know it is an added cost, but like I said, in the field time is money.

I'd rather be mining and processing in the field than fixing something, especially with the promotion at work that severely limits my time in the field now.

 

[Bill_saf]

I would go here and down load the steel handbook first http://pacific-steel.com/wp-content/uploads/2012/03/PSR_steelHandbook.pdf?944a87 so you know the weight of your steel first and build from there. Not that you get your rod mill built and the shaft will bend.

Bill

 

[kcm]

Randy Clarkson did some research on and came up with a rod mill design a few years ago. There are 3 .pdf articles for download that I have found so far. One articles is 4 pages, another is 39 pages and the latest is 56 pages. There's some very valuable info in these articles:

The 4-page link is:
https://yukoncollege.yk.ca/downloads/Grinding_for_Gold.pdf

Another 39 page .pdf is at:
http://www.geology.gov.yk.ca/pdf/141114_Nov1014_Grinding_for_Gold_Presentation.pdf

The link to the final .pdf (56 pages) article is: http://kpma.ca/assets/files/grinding-for-gold-report.pdf

In these articles, among other things, is specific information concerning building one of these rod mills for your own use. Has been a while since I read them, but I know that the 4-page article had info that the 56-page final didn't have....that is, unless I just didn't read close enough!

 

[Mad Machinist]

Randy Clarkson did some research on and came up with a rod mill design a few years ago. There are 3 .pdf articles for download that I have found so far. One articles is 4 pages, another is 39 pages and the latest is 56 pages. There's some very valuable info in these articles:

The 4-page link is:
https://yukoncollege.yk.ca/downloads/Grinding_for_Gold.pdf

Another 39 page .pdf is at:
http://www.geology.gov.yk.ca/pdf/141114_Nov1014_Grinding_for_Gold_Presentation.pdf

The link to the final .pdf (56 pages) article is: http://kpma.ca/assets/files/grinding-for-gold-report.pdf

In these articles, among other things, is specific information concerning building one of these rod mills for your own use. Has been a while since I read them, but I know that the 4-page article had info that the 56-page final didn't have....that is, unless I just didn't read close enough!

Those are kinda the ones we are talking about. If you look at the pipe he is using there it looks like schedule 120 pipe with a .718" thick wall, based on the information he gave of using 1" rods and scaling it with my "eyeball" scale. That would last a long time, BUT not everyone has access to pipe that heavy as it is a special use pipe and extremely expensive.

Most people are going to find schedule 40 or maybe schedule 80 pipe that size. And without a "sacrificial liner" of some sorts, it would shell out rather quickly.

I hate to say it, but used propane tanks are starting to look better and better. They can be cut safely if proper procedures are followed and most places sell them rather cheaply. Maybe make the shell out of one and cut up a few more for "liners". When one liner wears out, pop it out and slide in another that is ready to go.

I have been working on a rod mill idea for awhile now. Doing a continuous process design and trying to keep the cost down is NOT easy.

 

[Mad Machinist]

Dug back through some of my old posts. Here ya go. Hard to believe it's been almost two years since I started down this road.

http://www.treasurenet.com/forums/hard-rock-mining/420352-ball-mill-design.html

 

[kcm]

Thanks MM. Went back and looked - now I see whatcha mean.

Well, 2 things initially come to mind. One could take the time to cut flat plates of steel that use plow bolts going from the inside to the outside to hold in place. Threaded end extends to the outside of the mill and nuts hold it in place. The wear plates would last a long time, be very easy to make with a jig, and would be inexpensive. ...Might need to use flat washers as spacers where the bolts go through so that as the plates wear, they won't bow and allow too much grit to get underneath.

Another idea would be to take sheet steel - maybe 1/16" - and make a liner for the inside. With a little careful figuring, one could fit it so that there is a fairly tight seam where the two edges meet inside the drum.

MM wrote, "The mills I used to work on had 3" thick manganese steel liners and they would only last six months. Granted they were grinding 80+ tons per hour, 24 hours a day, 7 days a week, but the concept is the same. The only way I could see this design feasible for a small miner is if they were able to obtain the materials to build the drum and the material for the rods at little to no cost. Steel adds up quickly if it constantly needs replaced."

Ok, so the plate liners were mentioned already.

 

[Mad Machinist]

It's all good. At least your thinking of ways to make things better. Keep it up and we may just yet succeed in making a cost effective rod/ball mill for the small scale people.

 

[kcm]

Sad - here I've been doing TONS of research just waiting to make it out to the field, and now I think my plans are pulling me in a different direction! ...Oh well, at least I'll have this to fall back onto.