Electrochemistry Spilled sulfuric cell, now what?

[steveonmars]

I finally got back to running my sulfuric cell after taking a break for a while. I ran quite a bit and had a lot of black mud in the bottom and decided to quit for the day. Everything was outside so I just covered my cell and went inside for a while and we got one of our Florida thunderstorms that pop up all the time. when I went back outside the whole table was tipped over and my cell spilled out into the sand we have down here for dirt. I scooped up all the black sand (and small leaves and bugs) and have it sitting in an old coffee carafe but I'm not sure what to do with it now. It was under cover so everything stayed dry from the rain, the cell just leaked out into the dry sand. I have a few ideas but I'd like to hear some of your ideas first.

Thanks,

Steve

 

[ΩPhoenix]

I finally got back to running my sulfuric cell after taking a break for a while. I ran quite a bit and had a lot of black mud in the bottom and decided to quit for the day. Everything was outside so I just covered my cell and went inside for a while and we got one of our Florida thunderstorms that pop up all the time. when I went back outside the whole table was tipped over and my cell spilled out into the sand we have down here for dirt. I scooped up all the black sand (and small leaves and bugs) and have it sitting in an old coffee carafe but I'm not sure what to do with it now. It was under cover so everything stayed dry from the rain, the cell just leaked out into the dry sand. I have a few ideas but I'd like to hear some of your ideas first.

Thanks,

Steve

Hello Steve,

I would like to take a shot at that if you don't mind. It will be a fun one to solve don't you think?


Let's start with the assumption that the gold is still in its metallic state.

Am I right?

Okay if I am wrong let me know and I will start over.

1.Take a sample and wash it to remove all of the acid.
Wash it in a funnel filter and test the filtrate comming out of the
filter for acid with a pH paper after about 5 complete rinses.

2. Gather the filter with the material and place it in a drying kiln
or oven. Dry it and then roast it to burn off all of the organic materials
that have contaminated it. You might want to do this in a big iron frying pan.
It would be ideal if you had an electric kiln and place the materialin an
earthenware roasting tray to incinerate it at 600°C. This is important
to oxidize the organic materials. It is important not to have the
temperature so hot that the sand begins to fuse and trap your gold.
You want to just ash the organics.

3. Allow the material to cool once it has been ashed and carefully
transfer a small test portion of it to a 250 mL pyrex beaker.

4. Cover the material with muriatic acid and slowly add just a few
milliliters of nitric acid and wait for it to begin reacting before slowly
adding more nitric. Pre measure you hydrochloric/muriatic acid beforehand
so you know how much nitric to add. Be sure not to add the nitric all at once
or too fast or you may get a boil over if the contents.

5. After you have added all of the remaining nitric and the bubbling has
stopped you may apply some heat for about 20 minutes then remove from
the heat and let it cool.

6. Dilute it enough so that it is not a strong fuming acid
with cold distilled or deionized water and let settle.

7. Filter the acid and sand and proceed with precipitation, rinse, dry, melt, pour
as I've outlined in my blog.

If you are satisfied with your result, scale it up for the remainder of the lot.

Thanks

Steve
ΩPhoenix

 

[Palladium]

Very good advice. This may not be necessary but where it me after the roasting i would wash in hcl just as a pre-treatment before ar. Just to make sure.

 

[goldenchild]

I think this advice is sound but you have to keep in mind that with sand you will have to constantly stir in order for the acids to make contact with all your gold.

 

[Harold_V]

Very good advice. This may not be necessary but where it me after the roasting i would wash in hcl just as a pre-treatment before ar. Just to make sure.

Excellent advice, Ralph.

Harold

 

[Harold_V]

I think this advice is sound but you have to keep in mind that with sand you will have to constantly stir in order for the acids to make contact with all your gold.

It's also important to keep it in suspension when heating, otherwise you get local heating of the vessel (the bottom, which dries out rapidly), which promptly cracks when the contents are stirred. This is much like processing polishing wastes from the jeweler's bench.

Harold

 

[Oz]

This is a good time to use a hot stir plate. Do not use a good beaker though as your local “soil” (sand) with scratch it up terribly.

 

[steveonmars]

Thanks for all the advice.

I wasn't sure if just rinsing the sulfuric would be enough or if I should roast it all before rinsing. I was also worried that something in the sand itself would react with the acids in a way I wasn't familiar with.

I'll probably do this later in the week and I'll post my results. I'll try a small batch first and see what happens.

Thanks,
Steve