Auric Chloride Solution Color Check

[enragedcow]

Hi All-

We are processing some PCBs, and after doing the AP method, we dissolved the filtered/rinsed foils in Acid/Clorox. I expected a yellow-green color, based on what I'd seen on the forum here, but instead I got this deep red.

I did a search, and from what I understand, this is fine (and maybe even good?).

We precipitated the gold, and it's a very, very fine black powder. We have yet to melt or anything. Just wanted a sanity check to make sure the color of the solution prior to dropping looked okay

Without Flash

[img:600:518]http://www.precisiontechrecycling.com/images/gold2.jpg[/img]


With Flash

[img:600:534]http://www.precisiontechrecycling.com/images/gold3.jpg[/img][/img]

 

[lazersteve]

What color does a swab test of stannous chloride show?

If the gold is coming down black its sounds like you have some other metals in the mix.

The color leads me towards Palladium. What was your source material?

Solutions of gold that are very concentrated can appear orange or red. How much did you dissolve?

Steve

 

[enragedcow]

What color does a swab test of stannous chloride show?

If the gold is coming down black its sounds like you have some other metals in the mix.

The color leads me towards Palladium. What was your source material?

Solutions of gold that are very concentrated ca appear orange or red. How much did you dissolve?

Steve

Well, stannous test was useless, hence my just purchasing some Tin from you to make more Ours is definitely out of date.

As we added SMB, the color turned more and more yellow until finally being mostly clear. I kept what was left, just in case, since I couldn't test it.

After the drop, we had about 3 grams of powder. And actually, now that it has dried, the powder has taken on a bit more of a reddish orange color, but it's hard to tell exactly because it's *extremely* fine.

 

[OMG]

That's interesting. Very fine particles of gold can be red colored. (see wiki gold). It says that citrate ions are used to drop gold in that small of particles. Are you sure the red liquid was actually liquid and not a suspension of superfine gold in the liquid? With a particle size that small it would probably take for ever to settle and you might mistake it as a liquid.
Maybe you accidentally spilled some orange juice in the mix and had already precipitated some gold that looked red?

 

[goldsilverpro]

I think it's surely liquid. The Wiki aside, as the gold particles get smaller, it goes from metallic to light tan to brown to dark brown to black to purple. In 40 years, I've never seen red. If it exists, it seems like something you would have to intentionally create.

As Steve said, it's either very concentrated gold solution or it contains some Pd. In the second photo, it looks like a fringe of yellow (gold) at the edge. By the description of what he did, it sounds like it must be gold.

 

[Never_Evil]

Steve has mentioned it before. After you get your first batch of gold powder, redissolve with HCl and Chlorox and reprecipitate. This will remove any additional impurities.

 

[enragedcow]

I will have another batch out in a day or two - it's ready to go now, but finding time to do it is the tough part.

As soon as I get a 2nd batch, I'll post pics again, and I'll re-do the first one to see what happens.

 

[lazersteve]

Be sure you follow Harold's washing procedure before you redissolve the powder a second time. This is the key to getting the purity up. Really pure gold drops to the bottom of the precipitation flask in a matter of minutes and forms a spong like mass when precipitated from concentrated solutions.

Steve

 

[Anonymous]

I just done 2 batches of AC that were dark orange to red color. I had already washed the gold with water, hcl and ammonia a minimum of 3 times each. (more after the ammonia with water, hcl don't like ammonia).
the hcl in the beaker with the gold was clear before adding clorine, desolved to pretty yellow and then turned orange/red. I filtered the brew twice, and then added SMB. The brew immediately turned yellow, then brown and dropped a nice light brown gold. Both batches added up to 2.3 grams total, using 250ml total in a batch.