Muriatic and peroxide

[dick b]

I put 3 bars in mine 120* apart so when the weights get to the apex and fall, they drop into the space between the other two bars. I also held them up a little way so that the mash would slide under them and would not build up and not get crushed. dickb

 

[Platdigger]

****, I like your mill...think I will build one... 8)

 

[4metals]

Three lifter bars is best, you get maximum smashing effect from your crushing medium. However unless Lefty is using some super bolts I doubt he will get the effect without more weight in the media.

 

[dick b]

Plattdigger:

I used the wheel with no center hub with bolt holes in it. I think it is called a Budd style wheel. I uses 5 or 6 wedges and the bolts draw the duals together with a spacer between them. I haven't got mine up and running yet but it looks like Harold's only bigger in diameter and a lot narrower. Inside it looks like a 3 bladed cement mixer. I saw a photo of one that another person posted on the prospecting forums or the backyard foundry forum. The wheel sits on two rollers, one of them powered by a small electric motor and two small wheels mounted to keep the rim running on the rollers, a lot like Harolds. I will be running it dry with one charge at a time. I plan to put it in a box with foam lining to keep the noise down. The one question that I worry about is, if the rim is strong enough to hold up to the pounding. I'm only planning for it to turn at about 30 rpm or slower.

Hope this gives you a clearer picture. Good luck.

dickb

 

[Harold_V]

I'm only planning for it to turn at about 30 rpm or slower.

Don't guess at the proper speed. In order for a ball mill to work effectively, it should have the ability to carry the balls to the top, dropping them. If it can't do that, you'll grind by attrition, which will be slow, and correspondingly hard on the ball mill.

I can't recall the source now, but when I built my ball mill, the speed was calculated using a formula I found in a book. It could have well been Rose's The Metallurgy of Gold, but I wouldn't swear that it was.

Harold

 

[goldsilverpro]

From an old post:

From experience, I feel that, with too fast a speed, the balls will tend to slide around the perimeter of the drum, due to excess centrifugal force (grinding action), whereas, with a slower speed, they tend to drop (pounding action) from the apex. With too slow a speed, the balls drop too early, from too short a distance. The "critical speed" calculation proves this out.

Here's the formula for critical speed of a ball mill, from my copy of the "Chemical Engineer's Handbook, fifth edition, pp 8-26.". The critical speed (as I understand it) is where, at the top of the mill, the centrifugal force equals the force on the ball due to gravity. Therefore, for any speed less than the critical speed, the balls will drop at some point, as they approach the top.

Critical RPM = 76.6/(square root of the diameter of the mill, in feet)

For dry grinding, they recommend a speed of 70 to 75% of the critical speed. This can be increased by 5%, if the mill is unbaffled.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=3107&hilit=ball+mill+formula

 

[golddie]

I am curious to know some of the methods of the recyclers of computers
We have seen many videos some make it look very simple to recycle the components in a computer.
The pieces that are plated with gold and are easy to recuperate like fingers are treated first.
The plastic and some of the other pieces are also obviously worthless and separated.
What is the next process.
There is a lot of lead solder
How can we remove the lead solder from this batch