Gold recovery from my sulfuric acid cell.

Guys, I am at my wits end. I have invested large amounts of time and money and have been a member for 3 plus years and I am still an amateur.

I like the sulfuric cell process the best over the aqua regia. The problem is not stripping the gold. The problem is recovery of the gold. I have tried and followed instructions to the letter and I still can't recover enough gold to justify my efforts. I hear so many different opinions on how to do it yet none seem to produce the results needed to make it worthwhile. I hate to say how much I have invested into this project in time and money. It is embarrassing yet I am the type to not ever give up, but even following the instructions given and purchased by me still produce virtually nothing buy more frustration.

Stripping is easy, I have that down. Recovery is the real issue. I will gladly pay for more instructions and or help. I just need this crack the code or pull my head out because I am tired of not getting this to work.

Help, please. Just tell me what to do next. I have buckets full of stripped material but I do not want to touch them in fear of more losses. Please show me the pathway. I have Hokes book and studied it but it does not seem to focus on this process as much as it does sweeps and aqua regia.

Sincerely,

I think you should probably detail exactly what you have done thus far. What chemicals, what procedures, etc.

The statement of having "buckets of materials" concerns me. With a sulfuric acid cell, you should be able to filter the gold off, then directly melt it. Further refining may be done, but it isn't really necessary to get a button.

Thank you Snoman701 for your reply.

I use a sulfuric cell with the standard copper and aluminum contact points from my battery charger. The gold strips very well and easily. I then take sulfuric acid and pour it slowly into a 5 gal, plastic bucket that contains ice and tap water. In addition, I have the rinse water container where I put the items that have been stripped and rinse them in distilled water. Once all the stripping is completed I rinse the items very well and remove them from the rinse and ice and add that to the bucket of sulfuric acid, tap water, and black sludge. I leave it to settle for a minimum period of 24 hrs. undisturbed or until the water in the bucket is clear and all the black sludge is collected on the bottom. I never do anything before the 24 hour period is over. Then I siphon the excess water off and filter the sludge and begin a rinsing process where I rinse until the sludge settles quickly. Usually no less than 5 full rinses or more but never less than 5 rinses. Once I reach this point I dry the sludge and take the powder and put it in my furnace and heat the gold to 1070 % Celsius. When I try to pour it into a mold it comes out as a medium to light brown but I cannot get it to melt and gather in the furnace.

Do you see any problems with my process? I just don't see what is going wrong.

Correction, I remove the items from the distilled water rinse and add that water to the bucket water that has the ice and sulfuric acid and the sludge.

Correction again. It comes out of the furnace as a light to medium brown powder.

Your not getting the powders hot enough to melt them I’d guess and with dirty powders which is what you have you need to use some flux to allow the powders to melt properly.

I thought about that to and wondered if my new furnace is reading temperature correctly. I don't have very good luck using a melting dish. In fact I have 10 melting dishes that have a lot of my gold embedded in the flux and the dish it self because they won't gather. The gold I have gotten is a very bright yellow so I think it is close to being very clean gold. It's my understanding that you should not use flux in a furnace graphite crucible. Is that correct? I have not had very good luck with melting dishes and that is likely my fault but it seems that I lose more gold than I get using them. Any suggestions?

I don't think you've talked about your typical batch size. My guess is that you're performing the process well enough, but that the amount of gold handled with each batch/melt is fairly small. You may be experiencing normal "losses" in the process, but these losses amount to a large percentage of each batch.

You just mentioned gold embedded in the flux in the dish. If these are small (1-2 mm diameter) I'd say that's normal and expected if you happened to be melting only ~0.5g at a time directly from a wet sludge.

All that to say: maybe it would be best to combine sludges from multiple batches before melting.

The typical batch size and yield according to the instructions I purchased and with good quality items to strip are as follows.

A three pound batch of good quality items should yield, according to the results the instructor posted are between 4 and 5 grams per pound of quality items. I buy only high quality items and I run 1 batch of 3 pounds each. That being said, it should be yielding somewhere between 12 and 15.5 grams per run. The amount of sludge accumulated is commensurate with those expected numbers. There is a lot of sludge from each run. After the washes and before I attempt to smelt, the losses are about 1/3 of those numbers. Give or take. That should be yielding some where between 8 and 11 grams. The weight of the batch I am working with now (brown powder) is just over 7 grams so the numbers are close to what the instructions I use say. When I put the powder in the furnace it was black with some impurities. When I took it out it was a med to light medium brown. I feel pretty certain that it is the gold but it is not melting at the 1061 Celsius temp.

Can you post pictures? Of the cell, and your powder.

Yes, I certainly can. It may take until tomorrow. I want to watch the election results tonight. I will do my best to get them on here asap though.

Thank you for your help.

Are you setting the furnace to 1061 °C? I would suggest to at least set it 50 °C higher. Even if the temperature is just a percent off it might be too cold to melt the gold. Even different spots in the oven might have different temperatures and there is no guarantee that the spot the temperature sensor sits in is at the same temperature as where the crucible sits.
By the way, wikipedia says the melting point of gold is 1064 °C.

Melting takes energy and it is the difference between the melting point of a material and the surrounding temperature that moves the energy that is used to melt the gold. If the difference is small it takes a long time to heat the powder to the melting point and long time to melt too.
Imagine a day when the temperature is only a degree over freezing, ice melts very slowly, while on a day when the sun is shining and the temperature is warm, ice is melting very fast.

How do you know the expected gold content of whatever scrap you are stripping? (I assume you are working with gold plated material.) Did the seller tell you that?

Göran

No, the expected amount of gold comes from a person that is doing it himself and he is referencing his results based on gold plated items that he is reclaiming like gold plated rf fittings and others that have a thicker plate amount than items that take less abuse do to the constant movement over the contact area. Those figures are based on his results not the seller of gold plated items. I see the point made about temperature variation and I completely agree. I did try moving the temperature up some but did not go as far as a 50 degree increase Celsius. I think that may be a solution. I have sent a inquiry to the company I bought the furnace from to see if they approve the use of flux in the crucible or not. I actually have 2 different furnaces and the other one says absolutely no to the use of flux in their furnace or it will void the warranty. What is your take on that?

I have pictures of the powder and my cell however the cell is empty at this time. I have not been able to unlock the technique of how to post them on this site. Does anyone know how to do that exactly? I can't seem to get them on here.

Mountain Man said:

I actually have 2 different furnaces and the other one says absolutely no to the use of flux in their furnace or it will void the warranty. What is your take on that?

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I have no idea at all, I'm only using melting dishes for now. I don't have a furnace.

As for attaching pictures to your post, check Frugal's thread here : https://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=33&t=21374

Göran

It might help to say what type of furnace you are using as if I remember an old discussion well powder will not melt well or at all in an induction furnace unless you have some solid metal to start the process, if I’m wrong I’m sure someone will correct me.

To all of you that have tried to help me figure this out I want to say Thank You very much. I contacted the manufacturer of the furnace and explained my issue and they said the same thing all of you were saying. They told me to set the temp. at 1100 Celsius and to add some borax. It was in fact the solution and it melted my powder into a very bright yellow button.

Thank you all for taking the time to talk to me and help me figure this out. I am sure I will have more questions as I move forward with this adventure but with all of you so willing to help I am confident it will work out.

Thank you, all. Sincerely
Mountain Man.

Show the button off, we all like to see some gold.

Now all you need to do is to work out if your yield is inline with what you expect and to do that is quite simple and laid out in detail here on the forum, the powder you are producing is very easy to dissolve and using several methods, the button will be a lot harder so hold fire on melting everything unless you have access to an xrf gun so you know exactly what you have, not all buyers are thieves but...