# Laboratory model chlorine leaching unit



## Traveller11 (Jul 9, 2013)

Here are some photos of the unit I've built to leach gold from concentrates and ore. It is fashioned from descriptions of the Meares and Plattner process used in the late 1800's. I made it from 3" ABS pipe and fittings placed inside a piece of 4" ABS pipe. The motor is a gear motor with a 37.8:1 reduction drive, which turns the drum at about 11 rpm. Inside the drum is a paddle I made from an old plastic cutting board, held in place by friction, which keeps the ore mixed while turning.

The purpose of having a cap and valve is simple; ore and solution are added to the cap end, sealed in, and then, through the valve, more chlorine solution is added and all air excluded prior to closing the valve.

While the oldtimers used chlorine gas forced into water under pressure, I am going to use 6% Clorox bleach adjusted to neutral pH by small additions of acid. The results are almost identical, a solution of hypochlorous acid at neutral pH. Adding chlorine gas to water will also make small amounts of hydrochloric acid. This acid, also known as hydrogen chloride, provides a necessary element to the equation. This can be substituted with sodium or calcium chloride added to the solution.


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## Palladium (Jul 9, 2013)

I like ingenuity.


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## Traveller11 (Jul 9, 2013)

Palladium said:


> I like ingenuity.



It turned out to be a lot more complicated than I first thought. It looked so simple, but notice the rubber hose on the drive shaft and the rubber bands on the drum. Without these, there is not enough friction to drive this thing. The plywood "thrust block" on the end keeps the drum from wandering off the rollers and the collar on the drum (sawn from a 4" ABS coupling) keeps the rubber bands from migrating down the length of the drum.

While this unit might be large enough for someone with a very rich concentrate, it will likely have to be scaled up for the material I want to run through it. This is where things will start to get complicated. The oldtimers used lead lined airtight steel cylinders but I am hoping to make something from a larger diameter plastic pipe.


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## Gratilla (Jul 9, 2013)

T,

I agree, things will undoubtedly get "complicated" on scaling up this drive system. A more usual method is drive via v-belt/fan belt. I think you can find photos on the site posted by that Indonesian guy some time back of his milling/grinding drums. He had a burst of postings here and then unfortunately disappeared, apparently as a result of some "unfriendly" comments on the forum.

Also, there's a relatively modest max diameter for pvc pipe, above which you'd need to go steel. Lead lining shouldn't be too difficult or maybe a coat or two of epoxy (if the grinding action is not too much).

Care to post the results of your leaching?


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## Geo (Jul 10, 2013)

if you extended the "thrust block" and added a caster with the base vertical, the drum would have a wheel to turn against and lower the friction.


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## chlaurite (Jul 10, 2013)

For scaling this up, how about checking CL and the like for a used cement mixer (if handy with motors, you can easily fix 99% of the "broken" ones)? Some already come with baffles (or you can add your own again), and that leaves you really only needing an improvised cap.

Voila, same basic design with a 25+ gallon capacity.


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## Traveller11 (Jul 10, 2013)

Gratilla

I was going to go with a belt drive at first but a friend of mine had this gear motor. He suggested the drive system and all of the pieces were right handy. This type of drive is not uncommon on a large scale, though. I have seen six foot diameter trommels mounted on tire rollers and driven by the tires on a differential (axle) cabbaged from a pickup truck.

It is possible to obtain plastic pipe in larger sizes. It is the PVC pipe used underground in water systems. I may have access to a short piece that is 24" in diameter. Of course, finding a screw on cap in this size may be difficult.

Geo

Yes, I thought of putting a caster there but it was so much simpler just to put the piece of plywood there as a rub block. It still seems to turn easily and the ABS does not seem to be heating up. I'll have to improve on the design when I scale it up.

Chlaurite

A cement mixer would have to have a plastic barrel and the paddles would have to be plastic, as well, and mounted with titanium bolts. Any steel, even stainless steel, will be attacked by the chlorine solution.

That being said, it may be possible to adapt a cap to the mouth of a plastic mixer drum. It would have to be airtight, and it would have to allow some means for expelling all of the air inside and being 100% filled with ore and solution.

As can be seen, it is not hard to understand how leaching with cyanide replaced chlorine leaching so quickly in the early 1900's. Not only was cyanide leaching cheaper, it could be performed in open vats, as opposed to the airtight cylinder required for chlorine leaching.


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## rickbb (Jul 10, 2013)

This looks like the old rock tumber/polishers I've seen. Wonder if one could be converted to serve as a lab size unit. hmmmmm


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## Traveller11 (Jul 10, 2013)

rickbb said:


> This looks like the old rock tumber/polishers I've seen. Wonder if one could be converted to serve as a lab size unit. hmmmmm



LOL Rick, yes it could, but I couldn't find a rock tumbler for the price it cost to make this Rube Goldberg setup. :mrgreen: 

If it doesn't work out, my nine year old granddaughter (she is the hand model in the photos) has dibs on my creation for polishing rocks.


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