Gold.refinery
Well-known member
We have not glassware and fume hood
Waste treatment system at Gold Refinery
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The Italimpianti filter is the best filter you have, you should reserve it for your precipitated gold and nothing else. You don't want to contaminate it with silver.
That's a big filter for the relatively small quantity of silver you will recover. And for less than 2 ounces of gold you will have a hard time cleaning it all out.
Get a porcelain 2000 ml capacity Buchner funnel and a vacuum jug and it will handle all of your smaller lots and cleanups. It uses inexpensive 18cm filter papers available in a wide variety of filtration speeds.
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Having one will make your routine silver cleanups simple and you have the scrubbing capacity to add some scrubbed drops to handle any noxious fumes. Without a hood you will be forced, as you were when you converted the silver chlorides, to work in the open shop or use the tumbler for lots too small to handle effectively. The hood will be a welcomed addition for the folks that have to work in the shop daily.
AMS-Pro
Well-known member
Looks like someone needs to make a trip to Yamato, or Kalstein.
Get one of these type of setups, and run it parallel with your filter press if you're not changing your setup around.
Get one of these type of setups, and run it parallel with your filter press if you're not changing your setup around.
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It is very good for lye-sugar conversion of AgCl to have a vessel that is able to be heated. Sometimes I found very helpful to heat the solution near boiling point and the conversion is done (with good mechanical stirring) under hour or two.
Be aware of the fact that this is extremely exothermic reaction, which HAS INDUCTION PERIOD. So if you dump all of the syrup/sugar at once to the hot silver oxide suspension, it will spatter out of the vessel in less than a minute. Hot caustic eat flesh in seconds, trust me.
With bigger quantities, you absolutely want a thermometer sticked in the suspension. You will watch a temperature rise - it always have induction period, so max temperature is reached after some time, so be patient. When temperature stop climbing and start to go down, you can add another portion of syrup/sugar. To the 110°C it is usually fine, than it start to boil.
When you add portion of syrup/sugar and temperature stop rising, reaction is over.
I never experienced like 10 kg of AgCl in one batch, but I have done 2 kg of AgCl and you absolutely don´t want to overadd the sugar
Be aware of the fact that this is extremely exothermic reaction, which HAS INDUCTION PERIOD. So if you dump all of the syrup/sugar at once to the hot silver oxide suspension, it will spatter out of the vessel in less than a minute. Hot caustic eat flesh in seconds, trust me.
With bigger quantities, you absolutely want a thermometer sticked in the suspension. You will watch a temperature rise - it always have induction period, so max temperature is reached after some time, so be patient. When temperature stop climbing and start to go down, you can add another portion of syrup/sugar. To the 110°C it is usually fine, than it start to boil.
When you add portion of syrup/sugar and temperature stop rising, reaction is over.
I never experienced like 10 kg of AgCl in one batch, but I have done 2 kg of AgCl and you absolutely don´t want to overadd the sugar
Gold.refinery
Well-known member
After performing the initial operation and obtaining the silver metal powder,
in order to dissolve the silver powder in nitric acid and obtain the trapped gold,
for example,
how much nitric acid is needed for 1 kilo of powder?
What is the Specification of the reaction?
Is it hot?
Does it have fume?
in order to dissolve the silver powder in nitric acid and obtain the trapped gold,
for example,
how much nitric acid is needed for 1 kilo of powder?
What is the Specification of the reaction?
Is it hot?
Does it have fume?
Gold.refinery
Well-known member
Gold.refinery
Well-known member
Since a vacuum pump is needed for the Buchner funnel,
is a manual vacuum pump sufficient or should we get a separate pump?
Can we use the vacuum pumps of Refine device?
is a manual vacuum pump sufficient or should we get a separate pump?
Can we use the vacuum pumps of Refine device?
For AgCl conversion, you definitely need mechanical stirrer. Or stirring at least with drill bit for stirring cement attached to a drill. It need agressive mixing, otherwise it wont react and silver chloride will be left in the silver at the end of the process.
Magnetic stirrer can stir AgCl only up to 100-200g, 300 max. Then it just stop, because it is very difficult for the magnet to turn such a mass.
It takes 1.2 ml of 67-70% nitric acid to dissolve 1 gram of pure silver.
1000 grams X 1.2ml = 1200ml of Nitric to dissolve 1 kilo. You will also add the same amount of water as you need nitric acid. So a total of 1200ml of Nitric acid and 1200ml of water.
Will it get hot? Yes, Boiling hot!
Yes it will fume.
For future reference....... For copper It takes 4.15 ml of 67-70% nitric acid to dissolve 1 gram of pure copper. When using copper to cement silver from nitric acid (Not needed for agcl) it takes 1 gram of copper to drop 3.4 grams of silver from solution. But if you have excess Nitric in the solution it will chew up the copper and put off red fumes, before it will start dropping the silver. The silver that drops from excess Nitric will also be dirtier. That's a lot of extra copper and cost. That's why it important to watch the Nitric numbers when using the cementation process. With agcl excess Nitric is not a problem except for wasted chemicals.
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Gold.refinery
Well-known member
After adding nitric acid and water to the silver powder, the gold remains undissolved after the reaction is over.
We filter the solution and get gold.
Then we react silver nitrate solution with hydrochloric (HCl)acid to obtain silver chloride.
Right? (How much HCl?)
Caustic / sugar method again and obtaining pure silver powder.
I don't use hcl. I use regular salt for mine. Don't know those numbers. But if using hcl you can add about 500 ml while stirring vigorously. Give it a minute to stir. It's almost immediate. Then add about 10ml more and watch for a white cloud reaction. If you see the milky color of agcl add more. Keep running the same test until no more white milk is seen. At that point the silver is out of solution. Get you a notebook and keep track of all these formulas you will be using for future reference. It will serve you the rest of your refining career. That way using hcl you can a reference for your numbers.
And it will produce nasty, red, NOx, not something you want wafting about the shop and not a fume that I have ever found an effective mask to filter NOx out of the air column you breathe. This is a good example of the need for a fume hood in your shop. You will be doing this procedure routinely, it will never be advisable to do it in your tumbler plant which is connected to a fume scrubber. When considering what the daily operations are in a refinery such as the OP set up, I am surprised the manufacturer of the equipment didn't recommend putting a hood in place. And, the more experience you gain in refining, the more you will realize just how important it is to have a fume hood for testing and for small lots which will come in once you are established, and potential customers know you are a refiner.
This is one of the procedures a refiner learns to do by eye. Surely, we can calculate the exact stoichiometric quantity of either salt or Hydrochloric Acid but experience and simple testing will prove more practical in the end.
To test the solution to see if the silver is all out, simply take a single drop of the solution and drip it into a small beaker of chlorinated tap water. If the water coming out of your tap is chlorinated it will have a slight odor of chlorine, if not, a few grains of table salt or a milliliter or so of Hydrochloric Acid will give you the chlorine needed. If the drop of solution has no silver in it, the drop will disperse without a cloud left behind. But if Silver is present, a cloud of white silver chloride will be seen. This is a quick test which can detect very slight quantities of Silver. It is advisable if you use this test to try it on solutions you know to contain a decent quantity of Silver as well as diluted solutions containing very little Silver. Then you can see what to expect from the test.
The double diaphragm pumps on the Italimpianti filters are plumbed such that you can either provide suction to the filter or shut off that side and open the other inlet port to provide suction as needed elsewhere.
Provide the details and a photo of the double diaphragm pump on your filters and we can determine if they can do the same thing.
That's where the real butter comes from percentage wise. I have clients whom i charge 5-7% and then i have clients who i charge 20% for the same materials. Volume gets the discount, but i can make the same profit spread on smaller lots with less chemicals, processing, and time. I can make a $1,000 on a small lot or i can make $1,000 on a large lot, but at the end of the day i'm eating!
NUMBERS NUMBERS NUMBERS!
That's one i didn't know how to answer once i got to thinking about it. I mean i do, but i don't because i don't know what type of Buchner he's going to use it with. With my diaphram air pumps there is just a second between the cycles where the pressure or suction drops as it cycles from one side to the other. I have two different types. One has balls that check the flow and the other ones have fingers like a pyramid that opens on three sides and that closes to check the flow. Using a big filter with a hold down ring it doesn't matter, but with a filter that requires suction to seat the filter i was wondering about the filter paper floating at the edges and not sealing.
Good point Ralph. You could put a vacuum jug or a fat section of pipe with an inlet and outlet to hold a vacuum reserve and with valves keep the flow through the filter slower than the actual flow the pump can generate. Then you can assure suction to seat the paper.
I don’t know if I mentioned this, to many it is obvious, but with a buchner funnel you suck into a vacuum receiver which holds the liquid. The diaphragm pump will not be passing liquid in this application, just air.
Here, I would proceed slightly differently. Lye/sugar is much much more labor intensive than copper cementation.
I would advise to convert gold containing AgCl with lye/sugar to silver, RINSE IT VERY WELL FROM CHLORIDES, dissolve the silver in nitric acid in such way you do not use excess. Then filter the remaining undissolved gold, and cement the silver solution on copper to get the silver in one step without any big efforts.
I think this is all a matter what Gold Refinery is going to do with the silver.
It is absolutely true that for ease of obtaining a silver concentrate nothing is as easy as cementation. But the best he can hope for is 99% purity.
The first time around, with the silver chlorides from the aqua regia process the options all revolve around reducing the chlorides. So the options are either the Lye/sugar or the sulfuric/iron.
It's the re-dissolve silver, after the insoluble gold is recovered, and we have silver nitrate in a pretty clean clear solution as the base metals are out already from the aqua regia.
When considering all of the refining toys Gold Refinery has, we cannot forget he has a vacuum casting setup to make gold bars for sale. That same machine can produce (in different molds) silver bars for sale. Since this is an option, Gold Refinery can get the best price for his Silver bars. So I would choose Lye/sugar because it has the potential to make 999 silver for resale as bars. Why would he choose to use cemented Silver at 99% (on a good day) to cast bars for resale?
My first choice for the Silver bars would be electrolytic refining of Silver followed by recovery of the Gold from the slimes, but the volume seems too low for this and, to be honest, we have written over 20 pages on the refining and waste from Gold Refinery for a simple process like karat gold refining. I cannot imagine how long the thread would become for a soup to nuts description of electrolytic silver refining.
Yes, now I see it. You are absolutely right. Added value would be much higher in comparison with work.
I was considering he will somehow manage to setup small cell to refine to 4N Ag. But yeah, we still don´t have refining right
