New Refining Equipment

[kiwisue202]

Hi

I work for a company in New Zealand who is looking at setting up there own small scale refinery. We currently send it all to Australia but would like to further process here.

We are looking at doing around 1 Tonne a year. The silver content is around 3% and not very much else in there.

I have looked at BTT Italia for equipment. Is there anyone else you recommend?

Thanks so much

 

[FrugalRefiner]

1 tonne of what? Ore, industrial scrap, ewaste? What is the other 97%?

You've got to give us more information before we can offer you any good advice.

Dave

 

[kiwisue202]

Hi

Doree bars that are greater than 97% gold the rest being 3% silver.

Thanks

 

[orvi]

Hi

I work for a company in New Zealand who is looking at setting up there own small scale refinery. We currently send it all to Australia but would like to further process here.

We are looking at doing around 1 Tonne a year. The silver content is around 3% and not very much else in there.

I have looked at BTT Italia for equipment. Is there anyone else you recommend?

Thanks so much

Hi

Doree bars that are greater than 97% gold the rest being 3% silver.

Thanks

And what should be your outcome ? 99,99 gold ? or 99,9 is enough ?
For that ammount you stated, i will try to hire some professional refiners to set things properly and learn you all things. And also some security guards with that turnover...

For 3N this kind of material could be relatively easily dissolved in AR (when cornflaked), and then dropped with sulfite or plain SO2 gas (for better purity). Good wash with ammonia will remove most of the silver out.

I don´t know if direct electrowinning will be feasible. Too much silver. But i have no big experience with this method.
With basic AR dissolution/drop, and optimized seqence of washing and melting, 99,93+ will be possible reliably.
Few kg/week (few people working hard) could be processed even without "heavy machinery", but it certainly help a lot.

 

[4metals]

At 1 ton a year you are looking at a bit over 600 oz a week. Easily done as 2 lots in a standard 72 liter reactor and a simple set up. This could easily produce 1 lot per day so your production could grow 250% with the same basic setup.

 

[justinhcase]

I have never seen locking collars like that before.
A lab, you have to lock your reaction vessels instead of the door.

 

[4metals]

I have never seen locking collars like that before.
A lab, you have to lock your reaction vessels instead of the door.

They only lock the stone removal vessels because they fear an overnight invasion of their precious gems.

 

[Lou]

Hahah!

I'm with 4 metals, do it in a 72 L. This is low enough throughput that aqua regia would work.

The other option would be electrolytic if it's really 97% and 4N is a goal and some recycling of the anode butts is tolerable.

 

[4metals]

The only down side to electrolytic is time and accountability. You can’t account for all of your gold until you clean up the cell.
I’m a big fan of lot by lot accountability and matching up the pile or refined gold to the assay.

 

[nickvc]

In honesty with a throughput of 1 ton a year I’m fairly sure you have very good returns including pay out for the silver so unless you have customers for your own refined gold at spot or above the cost involved to do this may not be worth while , this material is really easy to refine and will fit in very easily into any large refiners processes but remember they make as much if not more selling bars and coins as from refining.
I think the first question you need to find an answer to is will your present refiner give you better terms for 995 or better material and if so how much better and will that cover the costs.

 

[4metals]

A complete evaluation involves knowing the rates he is getting and the turn around. If we were to know those facts, and the OP would get involved in a conversation here on the forum, we could really help this guy.
Unfortunately it seems he never got anything for his minimal effort and hasn’t been around since December.

 

[justinhcase]

At 1 ton a year you are looking at a bit over 600 oz a week. Easily done as 2 lots in a standard 72 liter reactor and a simple set up. This could easily produce 1 lot per day so your production could grow 250% with the same basic setup. View attachment 49189

I have a hard time with a 1000ml flask and sorting through filtered detritus for nice shiny stones with an eyeglass and pincers.
How do you sort that much, or do they just discard the really small stones?

 

[4metals]

So is the silver chloride giving you trouble and preventing the entire dissolution of the gold holding the stones?

 

[4metals]

Discard stones? Jewelers love you for that! Even the tiny melee stones they count.

I prefer to screen out all of the insolubles and rinse them well and place them in a plastic jar with a screw top lid. Add enough water to make a slurry and add a few tablespoons of sodium thiosulfate crystals. This is tumbled for about 15 minutes. This type of rock tumbler base works great.

Then all of the silver chloride is dissolved and the gold remaining is yellow again and all the stones are relatively clean.

If necessary you can put the undissolved gold back in AR to digest it to release any stubborn stones. The undissolved cleaned gold can also be melted into a small button and run the next time you refine karat.

The stones should be pretty clean but a soak in a small beaker with warm aqua regia cleans them up nicely.

The thiosulfate tumble can be repeated if there is a lot of Silver Chloride to start the process.

 

[justinhcase]

So is the silver chloride giving you trouble and preventing the entire dissolution of the gold holding the stones?

No, not really, I do have some settings that have survived a good five or six attempts at dissolution.
A very hardened Platinum group metal.
But on the whole, I have just been sorting through by eye.
NO were near the level of the afore mentioned reaction vessel and locks.
I tend to take off the deep set stones to one side from my main digestions.
Obvious extract all by mechanical means that can be without damage.
Then run them with A.R and ammonia wash alternatively.
As this is never a complete process there is always a bit of work separating, by eye stone, that which needs to be put forward for more digestion and which can be put to waste for further recovery of metals.
Good hour or two a week.
So a larger vessel would be a challenge to me, but then again, what would not tend to be?
I tend to be a little bit squint eye by the time I have finished most weeks.

 

[4metals]

What I prefer about thiosulfate over ammonia is the smell. With ammonia there is the white cloud and the stink so it needs to happen in a hood. With thiosulfate there is no stink and it can be done on a table in the refining area without exhaust.

It may not matter much to you if you are processing lots under 7 ounces if you are doing it in 1 liter of acid. And if you are using a 1000 ml vessel you shouldn't be using much more than 5-600 ml of acid to prevent boil over. So your lots are probably under 5 ounces. That's not such a problem.

Do a stone removal lot in a 72 liter flask like in the photo and you're digesting 300 ounces to start. That's a horse of a different color!

 

[justinhcase]

What I prefer about thiosulfate over ammonia is the smell. With ammonia there is the white cloud and the stink so it needs to happen in a hood. With thiosulfate there is no stink and it can be done on a table in the refining area without exhaust.

It may not matter much to you if you are processing lots under 7 ounces if you are doing it in 1 liter of acid. And if you are using a 1000 ml vessel you shouldn't be using much more than 5-600 ml of acid to prevent boil over. So your lots are probably under 5 ounces. That's not such a problem.

Do a stone removal lot in a 72 liter flask like in the photo and you're digesting 300 ounces to start. That's a horse of a different color!

Yes, white clouds if there is any hydrochloric about.
Always a good demonstration.
My largest comfortable reaction vessel I use regularly are 20,000ml.
I have one or two 100L units, but have never had the occasion to use them.

 

[goldandsilver123]

Discard stones? Jewelers love you for that! Even the tiny melee stones they count.

I prefer to screen out all of the insolubles and rinse them well and place them in a plastic jar with a screw top lid. Add enough water to make a slurry and add a few tablespoons of sodium thiosulfate crystals. This is tumbled for about 15 minutes. This type of rock tumbler base works great.

Then all of the silver chloride is dissolved and the gold remaining is yellow again and all the stones are relatively clean.

If necessary you can put the undissolved gold back in AR to digest it to release any stubborn stones. The undissolved cleaned gold can also be melted into a small button and run the next time you refine karat.

The stones should be pretty clean but a soak in a small beaker with warm aqua regia cleans them up nicely.

The thiosulfate tumble can be repeated if there is a lot of Silver Chloride to start the process.
View attachment 49209

I usually just tumble with iron nails and sulfuric acid.
How do you remove the silver from the thiosulfate? Dry and melt? Electrowinning?

 

[4metals]

Usually make a steel wool canister that used to be made for recovering silver from dental xray processing labs. The solution is slowly run through and the silver remains just as the silver thiosulfate from the film developing remained.

Then when the cartridge is full, melt it with steel rebar to reduce the silver back to silver metal and pour a silver bar.

I always pour the acid with the silver chloride and insolubles through a 100 micron polypro screen to separate all of the loose Silver Chloride from the crusty stuff. The loose chlorides are stored under a inch of so of water in a dark bucket until I have enough to reduce back to silver.

By screening out the bulk of the Silver Chloride the amount left encrusting the gold is greatly reduced so the canister lasts a long time.

 

[goldandsilver123]

Usually make a steel wool canister that used to be made for recovering silver from dental xray processing labs. The solution is slowly run through and the silver remains just as the silver thiosulfate from the film developing remained.

Then when the cartridge is full, melt it with steel rebar to reduce the silver back to silver metal and pour a silver bar.

I always pour the acid with the silver chloride and insolubles through a 100 micron polypro screen to separate all of the loose Silver Chloride from the crusty stuff. The loose chlorides are stored under a inch of so of water in a dark bucket until I have enough to reduce back to silver.

By screening out the bulk of the Silver Chloride the amount left encrusting the gold is greatly reduced so the canister lasts a long time.

Thanks!