white sediment in AP process

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Z

zenophryk

Active member
Joined
Jul 25, 2011
Messages
44
Location
Derry, NH
So I have 2 small batches of AP going. 1 just for fingers, this one has been working great. and another "experimental" flask. So in flask #2 I've mostly been doing differrent pins. all solder free. And yesterday about 3 hours after adding some pins (backplane connector pins from a dell server) I got a white/grey sedement in the bottom of the flask. Quite a bit IMHO. So today I filtered the flask off and I have a nice grey coating of sediment in the filter. when I hit it with a stream of tapwater from my spray bottle to wash it down to the bottom of the filter it turns bright white. the AP that I filtered out is almost brown, not dark green. however there is some green on the thinner parts of the paper. even when I added tap water to the original flask to rinse it out, the tap water turned a milky white.
Is this silver? something else? I would not have expected this much silver from these pins, but then I'm new at this and don't know what to expect.

-Zenophryk
 
CuCl (copper I chloride), is what I suspect, it will form when you have a lack of free HCl, it should dissolve if you add a little HCl to form CuCL2 (copper II chloride), I suggest reading the document on Laser Steve’s web site, if you have not already, to understand the copper chloride leach better, the other salts normally found that would not be water soluble cold, are lead and silver, lead chloride will dissolve in boiling hot water, silver chloride will not, but the rinsed silver chloride powder will get very dark when exposed to the light like in sun (photographic principle).
 
So I did read the document on LaserSteve's website about copper chloride, and I've been reading about it from other sources. Of course I've more been reading from a "getting started" mindset instead of a "now what" referance point, so I may need to go back to them and re-read. The document talked about determining the concentration of copper1 chloride by color. really dark green = high concentration. Never mentioned brown, or that the copper chloride would precipitate out on it's own (of course it could have said that and I missed it)
anyways. I will test dissolving the grey sediment with more HCl. I can totally believe it ran low on HCl

Edit: So re-reading the document, and of course it's right there "when the etchant solution is sufficiently diluted then Cu1+ precipitated out as cuprous chloride (a white solid)" and at 20g/L of Cu1+ it looks pretty brown.
 
Same happens if you heat your AP and have the water partly condesensed, CU(I)chlorid will drop out and remain as white cristals on the bottom, the blue CU(II)chlorid will stay in solution above the sediment. You can decant it off and reuse it then. At least that is what I did, correct me if I am wrong.
 
so I have been cementing out the copper from my saturated solution using aluminum. I should try heating it up and see what happens.
anyone know what's actually happening when I drop in the aluminum?
I assume an aluminum atom is getting swapped for a copper atom. but am I ending up with aluminum chloride?

-z
 
Aluminum will replace the copper from solution but aluminum chloride make a jell compound that is very hard to dry when treating for waste, iron works to replace copper and is much easier to deal with in waste treatment.

Copper dissolved in solution is an ionic compound (a dissolved salt of copper and the acid the copper is dissolved in) this copper is missing electrons from its atom (oxidized), when you put an elemental metal higher in the reactivity series of metals metal like Iron donates electrons to the copper ion, the iron dissolves into solution (oxidized)(iron changes places with the copper) and the copper which gains back its electrons becomes elemental copper metal powder (reduction of copper ion to metal).

CuCl2 + Fe --> FeCl2 + Cu

Look up and study the reactivity series of metals.
 
yes after putting urea to eliminate nitric acid i see not a very good fizzing when i put some ribbon of magnesium . I see some brown fumes come out from Aqua regia process then i put little smb and leave for one day then i see again if there is any nitric acid in AR process. I see this time not a big like before. I see some white kind of sand in the bottom. What is this As i think this is silver or what. But why gold is not participate.
 
I would keep magnisium out of solution, it will cement many metals form your solution.

The white powder can be many metals depending what metals were in solution like copper, silver, lead, and other metals, these powders may also contain metal salts formed from the urea and sodium salts, this all depends on conditions of the solution, and the steps you have taken to get to this point, and materials involved up to this point.
 
hciic said:
yes after putting urea to eliminate nitric acid i see not a very good fizzing when i put some ribbon of magnesium . I see some brown fumes come out from Aqua regia process then i put little smb and leave for one day then i see again if there is any nitric acid in AR process. I see this time not a big like before. I see some white kind of sand in the bottom. What is this As i think this is silver or what. But why gold is not participate.
Click to expand...
My friend
You speak as if everyone uses "urea" and "magnesium" every day in recovery and refining, and though they may have their place in some circumstances, they are not widely used except on youtube.
For your own sake, as well as the sake of anyone reading this who may lack experience, please do not bring "youtube science" (which is usually no science at all) to the board, at least until you have finished the basic research.
Edit : spelling
 
please do not bring "youtube science"
Click to expand...

Exactly! Most of the stuff on there is kids playing with chemicals("Oh wow, this is cool, I think I'll put it on YouTube") :roll: .
Stick with this forum and its members videos if you want accurate info. Some of our members do indeed have videos on YouTube and they are very well done.
 
A comment on (many of the) productions on youtube, and the net, in general.

We are inundated on a daily basis by new readers that cleverly start the refining process with aqua regia. The problems that accompany that process can be overwhelming, yet they persist. I'd gladly choke to death those who promote that foolishness, for it has created a nightmare for those of us who hope to help guys get off on the right foot.

My advice? Read Hoke, for a basic understanding of refining, plus a wealth of knowledge in regards to metal identification and testing. It also makes one familiar with terms used in the refining process, which are often strangers to those with no experience.

Then, pick one of the knowledgeable contributors on the forum (one you feel you can trust), and follow that person's advice. Not too good of an idea to try to listen to more than one, for each of us has our own way of working, which is often in opposition to the ways of another. In many cases, the outcome is the same, but the processes may or may not be compatible with one another, thus my recommendation to listen to just one person.

Don't take shortcuts. There is no such thing. If you cut corners, you can expect compromised results. A good example is in washing refined gold. If it is washed by the clock, instead of as long as is required, you can expect inferior quality. Learn to wash until the washes are free of color. Then, and only then, can you be assured that you have removed everything that can be removed.

Harold
 

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