Final ammonia water wash necessary ?

[goldsilverpro]

Is there a method to recover the silver from the ammonium hydroxide wash solutions?

Acidify with HCl and precipitate AgCl. You also end up with a safer solution.

 

[Harold_V]

Therefore there's no need to save the ammonium hydroxide wash solutions in the stock pot as there can be no gold in them?

Assuming you have introduced HCl to recover any dissolved traces of silver chloride, I agree. If you have not, I would send the ammonium hydroxide wash solution to the stock pot, which, in my case, was almost always heavily laden with HCl. That way I recovered traces of silver, which reported in the metals recovered when I processed my waste materials. I looked at it as a simple way to recover traces of value, without expending any extra effort. YMMV!

Harold

 

[Jonny5]

How do you know if wash worked will I have melting problems if added too much smb will the gold not melt properly

 

[butcher]

Luckily excess SMB would be water soluble, but unluckily using excess SMB can precipitate other metals with your gold like copper, this will be more of a problem the more base metals you brought over into your refining procedure.

How do you know if the wash is picking up impurity, is you will normally see the washes being colored by these impurity's, and the gold powders will lighten in color (example from dark brown towards a tan), also the gold powders settle faster and clump easier when more pure.

Usually gold will need refining twice if you expect High purity in your gold, you can only remove so much impurity with the washing procedures, rarely is gold pure enough (in my mind) with only one refining, even when the refining are done in very clean solutions, I refine the gold twice as a matter of practice.

Clean pure gold is a breeze to melt, and just a joy, the more impurity the more problems you will notice.

 

[Harold_V]

What butcher said. I refined thousands of ounces of gold in my years of refining. At no time did I ever achieve a level of purity that I considered to be acceptable when doing a single refining, which was made abundantly clear to me when the gold was melted. The melting process will disclose impurities readily, you just have to pay attention to the indicators melting provides.

That second refining eliminates those pesky traces of contaminants that refuse to wash out. Lots of reasons why that's true, thus the second refining makes it worthwhile, assuming you have a goal of high quality gold. Some folks don't have. Their objective may be far different from mine. My gold was sold for re-use, so quality was critical. The guy selling to a refiner doesn't have the same concerns.

And then there's the pride in doing something well.

Harold

 

[kadriver]

Harold, I just finished a small batch of gold, inquarted with silver, parted with 50/50 dilute nitric until final boil was clear of all traces of copper, then boiling DH2O washes until pH neutral.

Then dissolved in AR using incremental nitric additions, added a few drops of H2SO4 to catch any lead, evap down to syrup, hydrated with HCl then added some distilled water.

I filtered once to remove any junk (the solution was a touch cloudy) then dropped the gold with SMB.

I washed the powder several times with distilled water until pH neutral.

Then I did the second refining using AR and SMB (with a few drops of sulfuric).

The resulting solution was a bit cloudy, very slight.

I allowed it to sit in the refrigerator for an hour or so and I could see that the suspended solid was beginning to settle.

I went to the filter table and using a Whatman 542 fine crystalline filter tried to filter out the suspension.

I ran it back through the same filter paper and stopped counting after 20 passes through the same filter paper.

I was tempted to add a drop or two of silver nitrate to get the filter paper loaded up to see if I could get the suspension to filter out, but I did not do it.

Has this ever happened to anyone else? The suspension (probably silver chloride) refused to filter out no matter how many times I ran it through the same filter paper.

I ended up dropping with SMB then boiled the resulting washed gold powder in 28% ammonia, washed to pH neutral with distilled water, then a second ammonia boil followed by distilled water until pH neutral.

Then I dissolved again in AR and this time the solution was crystal clear.

There must be a certain point where the silver chloride is at a level that it just passes through the filter paper and never loads the paper up where the solution can begin to run clear.

Next time this happens to me, as an experiment, I am going to add a drop or two of silver nitrate to form some additional silver chloride to get the filter paper to load up to see if the solution will start to run clear through the filter.

I do not like working with ammonia, I used it one time with my vacuum filter rig and it ruined my vacuum switch.

But the ammonia sure does clean out that small amount of silver chloride that won't filter out - very nicely.

kadriver

 

[ericrm]

i dont know if it is good for you or not, but generaly speaking i got a better result gravity filtering in a number 40 whatman paper (fold in 8 ) than with a 50 tru a vacuum.

 

[kadriver]

i dont know if it is good for you or not, but generaly speaking i got a better result gravity filtering in a number 40 whatman paper (fold in 8 ) than with a 50 tru a vacuum.

I never thought of that, just use gravity instead of vacuum, excellent!

I have had many experiences with cloudiness not wanting to filter out of my AuCl solution.

I'll get some 40 Whatman and give that a go.

Thank you Eric

kadriver

 

[Geo]

I deal with it by letting the solids settle over night and then suctioning the solution off with a modified turkey baster. I then rinse the remainder into one side while the glass is tilted and let settle and repeat until the water is clear. I have more time than I need for some of this stuff.

 

[kadriver]

I've done it that way also Geo, it takes much time but it is effective.

 

[Sharding757]

I've just finished filtering a batch of pins and gold plated boards from my AP solution (separately), Washed the gold with boiling water to drive off any lead. My next step would be to boil in HCL prior to using the HCL/Clorox method. Would taking this step (washing with ammonia x2 then washing with water x2) prior to boiling in HCL then using the HCL/Clorox method better refine what im working with? Then once I dropped the gold repeating the process of boiling in HCL and then Ammoniax2 followed by h20 washing x2? In my thinking, I would figure, if I can get out any impurities while the gold is solid prior to dissolving it and dropping it, would that make a better product in the end? Thanks. Also would it be better to wash in ammonia first prior to boiling in HCL if this is indeed a better practice? Never heard of the ammonia wash till now so I'm all about trying to keep my impurities down!

 

[Lou]

The washing step should only be done on the final refined gold, and if you're refining it twice, it should be a minimum of 3N pure.

 

[Sharding757]

Thanks Lou..Just figured I'd ask since I stumbled onto this thread, I wasn't sure.

 

[kurtak]

I've just finished filtering a batch of pins and gold plated boards from my AP solution (separately), Washed the gold with boiling water to drive off any lead. My next step would be to boil in HCL prior to using the HCL/Clorox method. Would taking this step (washing with ammonia x2 then washing with water x2) prior to boiling in HCL then using the HCL/Clorox method better refine what im working with? Then once I dropped the gold repeating the process of boiling in HCL and then Ammoniax2 followed by h20 washing x2? In my thinking, I would figure, if I can get out any impurities while the gold is solid prior to dissolving it and dropping it, would that make a better product in the end? Thanks. Also would it be better to wash in ammonia first prior to boiling in HCL if this is indeed a better practice? Never heard of the ammonia wash till now so I'm all about trying to keep my impurities down!

Sharding

The ammonia wash is used to get rid of silver chloride from gold powders after you drop your gold from AR --- the Ag/CL is I trace amounts when working with things like gold fill - dental gold & carat gold (most of the silver has been removed in steps prior to taking gold to AR - but traces follow to AR)

You are talking about foils here - there should be no silver - therefore no need for ammonia wash

Kurt

 

[saadat68]

Hi
I don't like work with ammonia so I don't want to wash powders with it. Can we produce 24k gold without washing powders with Ammonia?

For example with washing gold powders with just water and hcl and twice refining, Can we produce 24k gold?

Thanks

 

[Shark]

Short answer is Yes. Long Answer, it all depends on how well you do your part, such as removing unnecessary base metals and other non target metals first. Your beginning materials help determine your first steps, and the following methods to reach your goal. Out of around 10 pounds of gold filled in 1 pound lots, all the gold I have recovered met my buyers needs of four 9's based on his XRF. If it is four 9"s or not I really have no idea, but it is his standard of doing business and that suits me. After a little hands on practice you will develop methods that seem to get you to your goal easily. That is, so long as your goal and equipment allow it, and you don,t expect more than they, and you, are capable of.

P.S.
You seem to be studying hard, all across the forum, and the more you know, the more you are capable of.

Good Luck!

 

[saadat68]

Thank you Shark

 

[MAB]

Yep---what Lou said. It also removes traces of silver chloride that have a tendency to hitch a ride through the process. Adding the ammonia wash to my cycle was when my gold quality took a noticeable turn for the better.

Harold

what is the ratio of water and ammonia being used for washing, or is the ammonia being used strait ?? also ammonia fumes can be explosive around an ignition source, so are you heating the ammonia with gold mud or doing a warm rinse ?

 

[Lou]

It was straight aqueous ammonia (that's what I used before I knew better). Heating ammonia is a bad idea. It also defeats the purpose of using it because it's a gas dissolved in water and room temp ammonia dissolves silver chloride better than half-distilled-from-solution ammonia at boiling point. The recommended practice now is conc. HCl, which is obnoxious, but good at dissolving AgCl with the minimum of gold. This HCl and its rinses can be saved and used for the next batch to recycle any fine gold that might be lost. In this way, ammonia is avoided completely.

One benefit to an ammonia rinse is you can see how well the copper has been washed off the sponge--blue tetrammine copper complex is very easy to detect against a piece of white paper.

 

[MAB]

The washing step should only be done on the final refined gold, and if you're refining it twice, it should be a minimum of 3N pure.

The washing step should only be done on the final refined gold ! Why do you say that Lou ?