Yet another Sodium Bisulfite question

[jsargent]

How specific is sodium bisulfite toward precip of PM's over the evil of evils, IRON? I am extracting daunting amounts of black sands and even though I wash them with vigor using citric acid to remove as much of the iron as possible, my lixiviant still floweth over with dissolved iron (chloride). Just did a test precip with SB on a liter of lixiviant and dropped half a gram or so the prettiest little 50 micron light brown spheres you can imagine. It took overnight but this morning there they were. I seriously doubt the bulk of this material is gold. If it is then the assays were off by several orders of magnitude and I will soon have my calls forwarded to Cabo San Lucas.

 

[Oz]

Jsargent,

If I remember correctly you are running very large batches but I don’t recall you mentioning the chemical process you used. With you mentioning such large quantities of Fe in solution I would be concerned that you may actually be taking all of your gold into solution but then having it precipitated by the Fe before you filter.

 

[jsargent]

Jsargent,

If I remember correctly you are running very large batches but I don’t recall you mentioning the chemical process you used. With you mentioning such large quantities of Fe in solution I would be concerned that you may actually be taking all of your gold into solution but then having it precipitated by the Fe before you filter.

I'm experimenting with this patent using Hcl, salt, monopersulfate and a pre-rinse with citric acid. Entirely possible the remaining iron is re-precipitating the gold from the chloride form. The assays are consistent at about 1/2 ounce/ton and I have enough of it to make it worth it for me to develop an economical method. My only constarints are no cyanide and I would prefer to avoid nitric acid as I became sensitive to it back in my chemist days and one whiff of it and I'm gasping for air and air is something I like.
Here is patent: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5401296.PN.&OS=PN/5401296&RS=PN/5401296