Gold Refining Basics Complete Process for the Home Refiner

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kadriver

kadriver

Well-known member
Joined
Oct 25, 2010
Messages
1,830
Location
United States
Here is another video I completed today.

The footage was taken in December of 2010.

I was going to make a detailed gold & silver refining video back then but decided I had better get some more experience as I was only on my third month refining gold & silver.

Good decision, as some of the stuff I was doing was frightful!

I had to edit out many sections as the material was just incorrect due to my lack of experience.

Even in this video, I precipitate the gold without a containment dish under the reaction vessel. I would not even think about doing this today.

None-the-less, it is a short and direct video of the gold refining process and good for getting a general idea of what is involved in refining scrap karat gold.

The equipment used and chemicals are presented in a general way.

Please review this for me and let me know if there are any glaring problems

http://www.youtube.com/watch?v=gTBBYogskS8

Thank you - kadriver
 
Excellent, Pete. The only thing I would question is whether you removed all the silver from the AR. It still looked a little cloudy before you added the SMB.
 
There may have been some left in there. I assume it is silver chloride.

How could I get all the cloudiness out of the liquid gold?

Should I have run the batch back through the same filter paper?

I just recently found that when I filter the gold after dropping with SMB and settling, some very fine gold makes it throught the filter paper. You can see it in the fitrate in the filter flask.

What I learned was this: Remove the funnel, transfer the gold-containing filtrate to another container, then put the funnel back together and run the gold-laden filtrate back throught the same filter paper.

On this second pass the filtered liquid was crystal clear. ALL the visible gold was in the filter paper.

I later burned the gold-laden filter paper to disintegration in a melting dish and recovered a bead of gold that weighed .3 grams.

How can I fix this problem of the AuCl being cloudy after filtration? To this day, I still experience it from time to time.
 
kadriver,

The silver chloride is somewhat soluble in strong AR, but much less so in weak AR. If you filter the strong AR, it may look clear, Then, when you add rinse water to the filter, you are diluting the AR and some AgCl will precipitate and the AR will get cloudy. There are 2 basic ways to precipitate the bulk of the AgCl so it can be filtered out before dropping the gold: either chill the AR with ice or dilute the AR with 3 volumes of water. The ice method has been covered several times on the forum (I'm thinking that 4metals, and others, covered it quite well). In the past, I always used the 3X dilution method. The main problem with this, as opposed to using ice, is that you generate more acid waste. After dilution, I added the sulfuric, so I could filter out both the lead sulfate and the silver chloride at the same time. After dilution and adding the sulfuric, I stirred the solution and let it settle until it was clear. I then siphoned off the clear top portion and filtered it. I then poured out the filtered solution into a separate clean container and filtered the remaining liquid and solids through the same filter paper.

The reason I diluted with 3 volumes of water is due to experiments I made way back in the 60s. I analyzed the dissolved silver in concentrated AR (using an AA) and then made progressive dilutions, filtered a small portion of each through a fine glass fiber filter paper and analyzed the filtered solutions for silver. I found that more than 3 dilutions produced no appreciable increase in AgCl precipitation. However, no matter what method you use, there will still be traces of AgCl remaining. Most of this can be removed by leaching the gold powder in ammonia (I heated the ammonia). You could eliminate the ice or dilution and try to remove all of the AgCl from the gold powder with ammonia but, in my experience, it works best to get rid of as much as possible before dropping the gold. As 4metals (I think) has said, the main contaminate in refined karat gold is normally silver.

When using vacuum filtration, I always had at least 2 clean flasks. With most types of filter papers, some fines (gold powder, AgCl, etc. - whatever you are filtering) will often pass through, at first, but then the paper will clog a bit and the solution will start running clear. When I observed the solution coming out of the tip of the funnel as being clear, I let what solution was already in the funnel run through, broke the vacuum by removing the vac tubing from the flask, transferred the funnel to the 2nd clean flask, re-installed the vac tubing to the 2nd flask, and then transferred the already filtered murky solution from the 1st flask into the funnel. I never turned off the vacuum pump while doing this. All of this can be done very quickly. The remaining unfiltered solution was then filtered through the same paper. That way, you only have to re-filter a small portion of the solution. In most every case, you will end up with a clear solution and all of the solids will be in the filter. With gravity filtration, I did the same thing, except I used 2 clean buckets. The type of filter paper can make a big difference. I'm not a big fan of coffee filters except, maybe, for very coarse filtering. For final filtering, I think Harold used Whatman 5. I often used Whatman 42. Both are quite slow. Many of the medium coarse, faster lab filter papers will eventually clog enough to prevent the fines from passing through.
 
Don't forget incineration after your first drop and rinses will also get AgCl to go up in smoke.
 
I can't ever remember incinerating anything (except filter papers, circuit boards, etc). With this obvious oversight (Hi, Harold), I still always seem to produce excellent gold - at least 999.5 Fine. Little different methods - same results.
 
I never incinerated my final product, although I did superheat it after drying. It's obvious that something is expelled when you do. I chiefly reserved incineration for when I'd change from one acid to another, when washing the raw materials. That was strictly to avoid dissolution of values prematurely. I do not consider incineration as a part of processing precipitated gold. That's one thing Chris and I agree on! :)

Harold
 
goldsilverpro:

Thank for that detailed explanation on filtering the gold twice through the same filter.

I have never refiltered the AuCl twice like you describe above.

My AuCl is usually a little cloundy, but every now & then I will get a perfectly clear (to my eye) AuCl after the first pass through the filter.

The bar that come from the beautifully crystal clear AuCl is alway quite smooth and free of any frosting or discoloration.

I can tell when the bar is going to come out looking good by the clarity of the AuCl after filtering.

Next time I get even a hint of cloudiness after filtering, I will use the process you wrote above.

My filter system is riggged to draw on an old 30 gallon air compressor tank, and then the 30 gal tank draws on the hose to the filter flask. This provides a reservoir of vacuum so I can shut the vacuum pump off after I get the vacuum great enough in the tank.

I also installed a small valve so I can turn the vacuum off while I change flasks.

We just never stop learning - especially when we have so many experienced forum members checking and recommending tweaks to our processes.

Thanks to goldsilverpro and this absolutely priceless forum!

kadriver
 
It really does work, Pete.

There are several precautions when vacuum filtering. The reason I let all of the solution the solution drain through before removing the vacuum hose from the flask is, without pressure from the vacuum, the paper will sometimes lift and the dirty solution can get under it. This, of course, would contaminate the filtered solution in the 2nd flask. Also, if the paper gets too dry after draining the solution from the funnel, it will sometimes wrinkle and lift. After transferring the funnel and re-hooking the vacuum hose, I usually squirt a little water on the paper and gently flatten with my finger in order to seal it before adding any solution.

With gravity filtration, there's no need to let the filter drain before transferring the funnel, since the solution in the funnel is surrounded by filter paper. However, the transferring of the funnel must be done quickly, in between drips, or you'll lose drips during the transferring. It's a timing thing - just watch and go. When setting up gravity filtration over a bucket, I used squares of 3/4" plywood, just large enough to sit over the bucket, with a hole cut in it of a proper size so that about 1/4 of the funnel was above the plywood. When observing the drips coming from the tip of the funnel, I found it safest to lift up the plywood and funnel together and look at the drips with good lighting. When transferring to another bucket, I moved both the plywood and the funnel together.

I usually had a series of sizes of vacuum filters, ranging from various sized Pyrex filtering flasks with Coors buchner funnels to 18" tabletop plastic vacuum funnels with several 5 gallon glass flasks on the floor. With gravity filtering, I used plastic funnels of various sizes. To me, some things filter better by gravity than by vacuum, and I usually had both. Due to the pressure, certain types of sludges tend to pack tight in the vacuum filter and filtration can slow to a crawl (like 1 drop per minute) whereas, with gravity, the sludge is looser and will often go faster. With some materials, both methods are slow as molasses. With something that goes fast, like AR with a little AgCl in it, or maybe pulped filter papers in AR, I prefer gravity, since there is less attendance required - you just add solution every so often. In a few (very few) places I worked, I only had gravity filters and this worked fine for most things. Buckets, plastic funnels, and plywood are cheap and I have had as many as 20 buckets with filter funnels working at the same time. There are many ways to skin a cat.

With vacuum filtration, I've used about every type of vacuum pump under the sun, from cheap aspirators on a sump pump and up. All in all, I prefer the Welch Duo-Seal pumps, if I can afford it. They're real workhorses, but you must have a good caustic acid trap to keep the acid fumes from getting into the oil. They're expensive new but you can sometimes find a good used one fairly cheap. A guy I was consulting for recently bought an excellent used one for about $500.
 
goldsilverpro said:
With this obvious oversight (Hi, Harold),
Click to expand...
Chuckle. Hey Guys.I haven't seen the two of you on the forum at the same time in a while.I am doing well.I still don't have the boat going,but a friend (who owns a boat store)owes me a favor for taking down 3 big oaks.He agreed to get the boat going before gun season opens.Well I have powder drying,so I better get out there and check on it.Have a good afternoon everyone.
 
goldsilverpro: I used the process you described in this post to get the AgCl out of the gold before filtering.

I added ice made from distilled water to the AuCl, then added sulfuric acid to precipitate lead sulfate.

The AuCl was cloudy when I went to the vac filter.

I poured the AuCl into the funnel, and after a few minutes the solution began to run clear out of the bottom of the funnel.

I grabbed another clean filter flask, shut off the vacuum, removed the hose and put it on the clean filter flask.

Then I carefully took the funnel off the first flask and placed it onto the clean flask.

The result was a completel clear solution after all was passed through the filter.

Thank you for helping me solve this problem.

kadriver
 
Pete,

Just watched your video on home gold refining. I have collected a considerable amount of gold plated and Rhodium and gold plated scrap from boeing 747 aircrafts from the electrical systems. Do you have a suggestions on how to strip the gold plating at home and also the rhodium? I would really appreciate any feed back you can give me.

Thanks Scott
 
Not to sure of a simple way to recover the rhodium but with your gold go to lazersteves site and watch the video of the sulphuric cell.
May i also suggest you read C.M. Hoke and all the safety sections on here and spend time to learn before you leap into refining or recovering anything, keep collecting while you learn. Welcome to the forum and take your time and be safe.
 
nickvc said:
Not to sure of a simple way to recover the rhodium but with your gold go to lazersteves site and watch the video of the sulphuric cell.
May i also suggest you read C.M. Hoke and all the safety sections on here and spend time to learn before you leap into refining or recovering anything, keep collecting while you learn. Welcome to the forum and take your time and be safe.
Click to expand...
Lou the moderator is thd resident PGM (Platinum Group Metals) expert. maybe contact him.
That being said, learn, learn, learn.
 
maclernon,i would do the folowing: to the gold and rh plated material i would add nitric acid +distilled water,doing this and filtrating i would take the gold foils and the rhodium foils formed in the nitric leach and dissolve them in ar-----the gold will go to solution and the rhodium foils would stay as rh foil-----the rh would be further purified with sodium bisulfate .
i do this every day with plated fantasy jewllery
regards
Arthur
 
wxfreqrs said:
OK G "day all
newbie here
why was silver added to the scrap gold in the begining
Don
Click to expand...
This is a classic example of why you are (along with all readers) constantly told to read Hoke. Once you have, that won't be a question you'll need answered.

No, I'm not trying to be rude. It's just that in order for you, or anyone, to be successful at refining, it's important that you understand the basics. That's exactly what Hoke teaches, and in a way that makes it easy.

Please do yourself a favor and start reading her excellent piece of work. You'll never regret expending the effort.

Harold
 
I feel many people come to the forum thinking refining metals would be a simple process, that they could learn by just asking a few questions, many times they have read a little on the intranet that gave them some instruction usually flawed in the details of the process, but it made it sound so easy just pour in some acids or chemicals and by magic you end up with pure metals, then they come here to learn more, to add to the confusion most want to refine metals from electronic scrap (many complicating factors involved), which first must be recovered before refining, and the there is the many different methods and processes we use to recover these values.

When they ask a simple question they get an answer like go study, and read Hoke's book,
For some that is no problem for they want to learn everything they can about something they are interested in, for others it seems like an obstacle to their goal of extracting values and refining them by some perceived simple method why waste time reading and studying we just want to get our gold.

It is only until someone has been around this for a while and try it out do they begin to see the vast knowledge one would need in this field, and after understanding will they see the value in Hokes book, even though she does not go into processing ore or electronic scrap, she does prepare the reader for learning how to process them, and also helps the reader to understand much of what we discuss in many of the other processes we use here on the forum.

Also until you gain some understanding in this field you do not know how much you do not know.

If the beginner in this field comes here and try's to jump in and start refining by asking questions we end up discussing how to get out of the mess they made, so much of what we discuss for new people coming here seems to be parts and pieces of processes (many different processes), and trying to put all those pieces of information together into one understandable meaningful way for which process to use or how to complete one process even gets them more confused.

Harold’s and others advice to read Hoke's book will help to clear this confusion, also the welcome in for new guys and general reaction list and other tools are important to get them going, advising them to learn on simple processes Like Hokes experiments getting acquainted and referring them to simple learning methods
Such as processing memory finger's, Directing them to Laser Steve’s web site and other information peoples videos and tutorials made by trusted members of the forum, like GSP’s book on silver.

Helping members is great,

But helping a new member who has not done his homework, and trying to answer every question he comes up with as he stumbles and bumbles through a process he is not prepared for, only makes many more posts for the next new member to stumble through to learn what he needs to in order to get started, and it only slows progress for both of these new members.

It is better to point them in the direction they need to learn (teach them to fish), than it is to spoon-feed them fish. Then we all learn to feed ourselves each other and the forum.

wxfreqrs you have been given the best advice possible to put you in a position to become successful (from one of the best people to learn from(Harold)) you can find a free download to Hoke’s book, in book section and in the links under members post's like Palladium's posts. I bought my hard back Hoke’s book from action mining (they have a website and online catalog), I belive GSP has also posted one of the cheapest places he found to buy the book, the book may seem expensive but if your serious about learning this I will say you will not regret buying it (I love my little book).
 

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