consolidation of Loss Gold thread

[4metals]

I think, on the subject of filtration, your filters are a weak link in your system. The pump used on the filter is strong enough to do the job properly but I think the design of the filter is a problem. The actual filter media is only propped up from the bottom by a short distance. I think this is the issue. In other systems the area beneath the filter is large enough to form a vacuum reservoir. The vacuum is powerful enough to warrant a center support to prevent the flat filter plate that holds the paper from bowing down. It is entirely possible that your plate bows down and actually inhibits suction.

These are photos of what is under the deck on an Italian system, note how large the under plate area is.

The paper is held in place with a rubber gasket which sits between the plate and a lip to securely hold down the paper and screen to the perforated plate.

This gasket has to be pushed in by hand to make the seal.

The pump is permanently mounted to the moveable base so the filter can move about the shop.


And Ralph, don't even ask what these cost!!!!!!

 

[Yggdrasil]

I think Gold Refinery realizes by now that filtration is critical to the final purity of his gold. Showing us detailed photo's has been helpful because it is easy to spot small inconsistencies, as Yggdrasil just pointed out.

It may be an accident while showing us his system.
That’s why I asked.

 

[4metals]

This is what the de-watered gold sponge in the Italian filter looks like. Enough moisture has been sucked out for the cake of gold sponge to crack because there isn't enough moisture to keep it together. This gold is ready for transfer to a melt furnace without further drying.

 

[4metals]

It may be an accident while showing us his system.

I think in the long run it will benefit him as he will know what he needs to do to get the equipment to perform at the level he needs.

But the manufacturer should be embarrassed!

 

[Yggdrasil]

This is what the de-watered gold sponge in the Italian filter looks like. Enough moisture has been sucked out for the cake of gold sponge to crack because there isn't enough moisture to keep it together. This gold is ready for transfer to a melt furnace without further drying.
View attachment 50301

Now I became curious, how do you lift out something like that without dropping anything

That is a challenge I’d love to have one day

Edited for readability

 

[4metals]

Now I became curious, how do you lift out something like that without dropping anything

That is actually a challenge, usually the gold is dry enough to lift out the larger chunks and then, with a small dustpan, brush the loose gold into the pan. When most of the loose gold is out, the gasket is removed, and the paper is carefully lifted from the edge so anything loose falls to the center. They continue around the diameter lifting until the sheet is out from under the lip and the remaining gold is towards the center, then the entire sheet is lifted out.
Ripping the paper is the biggest problem but in a short time with a few practice loads it becomes routine.

 

[Gold.refinery]

Stannous chloride Test:
I made a stannous chloride solution with the formula 4metal.
We have now tested some of the yellow solution that remained in the cylinder filter. See the details in the video.
Please guide me with more details.
Where should I drain the brown solution? Where should I sample the gold tank?
What is it like to test dirty solutions after depositing gold in the next tanks?

 

[Gold.refinery]

usually the gold is dry enough to lift out the larger chunks and then, with a small dustpan, brush the loose gold into the pan.

We could not dry the gold sponge in the last operation as much as the photo you sent with diaphragm pump.
Then, for better drying, we poured it in a steel container (????) and dried it with heat.
A lot of time wasted. We got bored.
I think some impurities (Fe) also entered the pure gold powder, which at the end of melting, made the surface of the ingot difficult.

What to do for quick drying without deducting gold and impurities?

 

[Gold.refinery]

I meant the filter paper do not cover the whole area.

Paper filter suppliers are not larger than 58 cm. They also do not know the size of the mesh. !!!!
We are looking for a roll paper filter with a 2.5 micron mesh.

Another solution is to make the filter gasket 2cm wider.

Question:
Depending on the type of our pump that was sent in the photo, is it necessary to replace the grid under the filter, which has large holes, with a 5 mm hole grid? (according to Italian systems)

 

[Gold.refinery]

I have many questions about different topics, but I will not mention them yet, to focus on the topics. Please, after completing this route, (4metal) ,
I will ask some questions,
also you confirm what I learned from members.

 

[4metals]

Where should I drain the brown solution? Where should I sample the gold tank?

The solution in the canister filter is definitely holding gold, as confirmed by the stannous chloride. And you were of the opinion you rinsed it thoroughly. That is why those filters have no place in the line with gold laden aqua regia.

The brown solution has gold in it and is difficult to filter. For this reason I never test in solution as you did in the video. If you were to pour out the liquid and use a piece of filter paper or paper towel to hold the sample you test. Simply dip the end of the paper into the liquid and let a small amount be absorbed, or use a glass rod and dip it in the liquid and allow those drops to drip on the paper. Then you add your drop of stannous chloride to the drips of sample on the paper. It will indicate accurately and you have used very little liquid. The papers are collected in a container where they can be accumulated and later burned and sent out for refining. (The manufacturers of these tumbler plants often say they can process sweeps for gold. Filtration is difficult and you never get all of the values.)
The remaining liquid (only if you have not added stannous chloride) can be put in the tank where you will be doing your next gold drop.

My suggestion, take that filter out of the line once you get the filtration process in your big filter ironed out.

You can stir the liquid in the gold tank and sample the liquid the same way, by wetting a glass rod and adding a few drops to filter paper.

 

[4metals]

What to do for quick drying without deducting gold and impurities?

If you have to dry in a metal container, use stainless steel trays.

If you send a few photos of the inside of the filter you showed us in the video so we can see just how high above the base the plate sits. Perhaps we can figure a way to get you some space under the filter which may help. That filter, working properly, will save you time.

A lot of time wasted. We got bored.

and prevent boredom!!!!

 

[4metals]

Question:
Depending on the type of our pump that was sent in the photo, is it necessary to replace the grid under the filter, which has large holes, with a 5 mm hole grid? (according to Italian systems)

It's not the size of the holes because the fabric is supporting the paper. The issue, I believe, is the fact that you cannot generate a sufficient vacuum reservoir under the plate because the grid is so close to the bottom. If you notice the Italians have a much greater space under the grid. Their pump is as good as yours so that is not the issue.

You also need to have the entire edge of the filter paper under the gasket. If solution can sneak around the edges the vacuum will take the easiest path too and a strong vacuum will never develop.

For now, if 58 cm papers are all that are available, have a wider gasket made and cut 58 cm circles to put into the filter. The guys can do it while waiting for the gold to dry!

 

[Gold.refinery]

If you send a few photos of the inside of the filter you showed us in the video so we can see just how high above the base the plate sits

 

[4metals]

Looks like the grid sits at most 4mm off the bottom.

The ring that holds the grid off the bottom that is fixed to the bottom is all that is lifting the grid? Is it the same as the piece you put on top of the paper to seal the papers?

If it is, and you have a few of them can you try to put 2 more down under the grid to raise it? Then you can cut some short lengths of PVC pipe the height of the stacked spacers. The pipe will support the grid which I fear will bow downward. If you place a few of the pieces of pipe around the center we may be able to prop up the grid enough and create an airspace below.

 

[4metals]

I just looked more closely at the video. That grid sits completely flat on the bottom inside the ring. That is the problem. We need to raise the grid at least an inch, preferably 2. (5cm) off the bottom. This may be something the manufacturer of this equipment can do for you.

If the manufacturer can add a few rings to the filter body so the grid is 5cm higher and add the equivalent spacers to the grid so it sits above the bottom it will be better. You will still need the short pipe pieces (with scalloped ends so they drain) to place under the grid because you can see when it is lifted it bends.

 

[silver1]

I think, on the subject of filtration, your filters are a weak link in your system. The pump used on the filter is strong enough to do the job properly but I think the design of the filter is a problem. The actual filter media is only propped up from the bottom by a short distance. I think this is the issue. In other systems the area beneath the filter is large enough to form a vacuum reservoir. The vacuum is powerful enough to warrant a center support to prevent the flat filter plate that holds the paper from bowing down. It is entirely possible that your plate bows down and actually inhibits suction.

These are photos of what is under the deck on an Italian system, note how large the under plate area is.
View attachment 50296
The paper is held in place with a rubber gasket which sits between the plate and a lip to securely hold down the paper and screen to the perforated plate.
View attachment 50297
This gasket has to be pushed in by hand to make the seal.
View attachment 50298
The pump is permanently mounted to the moveable base so the filter can move about the shop.
View attachment 50300View attachment 50299

And Ralph, don't even ask what these cost!!!!!!

Oh i know better!

You're right as i think about, not enough space under the plate. I ran into the same problem with my first design concept.

An easy fix could also be made with a 3d printer cheap and effectively.

 

[AMS-Pro]

I believe I'll chime in at this point.

First, I'd like to say thank you to 4metals for inviting us all together on this one, the private message was definitely a bit bare on information.
I would say the filter picture in your second post of this thread definitely looked troublesome. I thought maybe it was just the angle of the picture, but it appears not to be.

Nitpicking out of the way first:

I do have a problem with the valves shown (orange handle), I feel that the internal design of the flap (I'm assuming its a butterfly style) may catch sediment, but this would only be a very small amount. As far as valves go, I'm a fan of knife gate with a cleanout access.

Some of the elbows, and angle of piping seems either sharp or severe in some areas, and could affect flow rates, or where hidden deposits of sediment could build.

Both of these nitpicks could cause a loss, but it would relatively minimal at the scale we're discussing.

Onto the Filter:

A client of mine had a similar setup to what was pictured here, there were several problems that it posed:

1: Once the filter material started to get packed, usually from the center out, the edges would start seeing a higher flow rate and would slightly lift/curl the edges. and cause the seal to get pulled or loosen.

2: We had also come to a determination with the holes in bottom of the housing were a bit large and the filter material was allowed just enough space to settle into them slightly, like tiny little puddles potholes. With enough of those little indents (potholes/puddles) added together, it had pulled the filter taught/inward on the edges, which in turn would aid in the seal loosening.

3: Cleanout of the dry/cake material was a pain, it seemed you could never get it all. This was mainly seen when the seal and filter material were pulled, it seems the sediment would collect/ get packed between the filter material and the seal, and between the seal and the housing. Although this is not quite a loss as it is able to be collected, recovering all the sediment that had found its way into the seam (where the edge of the filter material/seal was pressed into) was extremely tedious to get recover, and would cause a poor seal on the next run if care was not taken to recover every last bit.

This problem seemed to build with every run, and the quality of the seal worsened slightly ever time. This resulted in the filter material becoming dislodged more often as time went on, number of runs increased.

The solution we came to for my clients setup was to modify the internal area of the filtration chamber, and it was converted to a multi bag setup. We had designed a drop in skeletal system in CAD to fit the existing chamber perfectly. The skeletal system had 9 vertical mesh cylinder chambers that the bags could drop into, the top plate of the skeleton system was welded into the existing chamber to eliminate any chance of sediment buildup on the edge. The inspiration for the idea came from a filtration system designed by a company named PRMFiltration, but like the OP here, my client already had a chamber that we could work with, so we just designed an insert..

Below I have inserted some pictures from the PRMFiltration website that gives you an idea of what I am referencing, you can look on their website for setups that more closely relate to yours.

Since we have converted my clients setup over this to this, cleanups have become much, much easier, and the previous issues we had are no longer present.

 

[Gold.refinery]

I do not understand why you want to test tin, but I assume you wanted to test gold with tin (II) chloride. Correct me if I am wrong.

It is wise to take one afternoon and get familiar with stannous chloride test. It´s quick, cheap, straightforward and work to quite a dilution (good test can catch 0,1g/L gold, if trained eye is watching).

Firstly, prepare stannous chloride testing solution with recipee posted before here. Store it in airtight container - because oxygen in the air will slowly decay the solution.

For learning and "testing the stannous testing solution", it is necessary to have one standardized gold solution to prove the test is working. Remember, you will only use one drop at the time = you do not need half a liter of it

Take 0,1 g of gold and dissolve it in AR. After completely dissolved, adjust the volume of the solution to 100 mL. Voilá, you now have 1g/L standard gold solution. I will also advise to pipette like 1mL to two separate vials, and adjust the volume to 2 mL and second to 4 mL, respectively. These will produce solutions with strength of 0,5g/L and 0,25g/L. Test these "surely gold containing" solutions with stannous test and observe the reaction. You will clearly see the strong violet-black reaction of the 1g/L solution. As the concentration goes down, colour will be more violet and below 0,25g/L slowly start to vanish. Opposed, if you test the pregnant solution straight from the reactor, you will get completely black, very dark test - because concentration is very high, far more than 1g/L.
You need to see this with known standard solutions BEFORE you will test the real life refining solutions and rinses.

I made the standard gold solution. Dissolve 0.1 grams of pure gold in AR , Then add about 100 ml liters of water.
Then I tested with different concentrations with stannous chloride.
Different colors were created.

But the question is whether the solution we want to test during the refining operation is opaque green, and combines with the colors shown Below.
How to recognize?

 

[4metals]

When the acid is a combination of the gold and copper and zinc in the alloy you are refining it will be a green solution. If the acid has a few grams of gold per liter it will instantly become a dark black liquid and easy to recognize.
I think you will find it easier to identify the different concentrations if tested on paper.