Non-Chemical Salt formation with AC

[skyline27]

I've been having problems with dropping gold lately. Everything dissolves nicely and I cook off chlorine on a hot plate for 30+ minutes. Add the SMB and...nothing.

After the gold is dissolved in AC and I filter out the crud, how do I rinse the gold solution through the filter without dissolving the salts back into the solution? I don't know where I'm going wrong.

 

[lazersteve]

The salt formation is a common occurrence with HCl-Cl. The salt can be from several sources including sodium chloride from the bleach and acid mix, silver chloride from the dissolved gold, and other metal chlorides.

To clear up the salts first let the solution cool completely. Once cooled most of the salts will have formed. Filter the solution until it is 100% free of any floating particles. A normal plastic funnel packed tightly with unscented Charmin in the neck (2-3 sheets works fine as the 'Charmin plug') will clear up the solution quickly. The packing must be loose enough to allow the liquid to pass thru at a rate of a few drops per second, but not so loose it lets the floating particles thru. I use this set up with a vacuum assist to pull the liquid thru quicker.

If you are not getting any gold to precipitate check the solution with stannous to be sure gold is present. If the solution is positive for gold be sure you are using Sodium Metabisulfite not 'bisulfate'. If you are sure your SMB is good then add some more until the color changes and the gold should drop. As a side note, I seldom if every have to evaporate off any excess chlorine to get the SMB to work.

Steve

 

[skyline27]

Thanks for the info. One more thing. The filter will be stained with the gold solution. I've been using a spray bottle to wash this out. Am I pushing salt back into the solution by doing this? One thing I'm sure of is that I need to be more patient at this step. I get all excited to see that powder!

 

[lazersteve]

Yes, any soluble salt will end up back in the gold bearing solution. Using cold water can help reduce the amount of salt that returns to the solution. Silver chloride and some other base metal salts will not easily dissolve in water so they will stay in the filter. After adding the SMB let the solution stand overnight to fully settle.

Steve