A serious Gold Filled head buster.

[jamaicanyute]

Hi ,
I hope this one does not give anyone a headache. 2000 grams of mixed GF. Took that to incinerator for 2-3 hours. Washed off with water. Nitric ( used approx.2 + l.) acid for approx 12 hrs. We let it settle then decanted liquid, GF looked liked the base metals had dissolved, everything was mushy to the touch we rinsed it as good as possible. HCL added to GF (10 l.) immediate reaction due to nitric in GF ( didnt rinse good enough) got a nice yellow reaction then as more nitric got added it went green ( GF nitric acid bath did not dissolve all base metals). We decided to go through with AR till we had everything dissolved, solution at the end of AR is dark green with fine precipitate floating and appearing as water is added. The day of AR we got a good stannous result , I'm still filtering AR . But stannous this morning shows NO gold. Could the base metals that were dissolved be automatically dropping out everything ?

 

[Geo]

watch the stannous test closely. are you using a spot plate or a Q-tip? when you drip the stannous on the test, does it give a quick flash of color and go back clear? this is a common false negative caused by too much free nitric acid in the solution. did you neutralize the free nitric before the test or after?

 

[jamaicanyute]

I did about 300 -500 ml of evaporation ( don't think I did enough because upon diluting I got some brown vapors ). I get no color flash just a clear slight green on filter paper. I'm gonna filter AR and get rid of the nitric all together then drop with copper, how does that sound?

 

[Geo]

no need to filter again if you intend to cement on copper as it will be contaminated anyway. was there there any solids left from the dissolution? if so, do you still have them? if there wasnt any solids and there was gold in the material, then it has to be in solution whether stannous shows it or not. a solution with an excess in nitric acid will show negative for gold.

 

[jamaicanyute]

I have some GF left after dissolution but not much very little, i have em in a filter. Just finished filtering my AR and the picture is what i have left at the bottom of vessel. Is that the sponge thing everyone says is a headache to deal with ?

 

[jamaicanyute]

Hi All,

Im still having a grand ole time processing this Gold Filled, The pic in the previous post is what I had at the end of filtering my AR, alot of brown and black powdery/spongy looking stuff. I also have quite a bit of filters, from the AR. I started with 2000 grams of Gold Filled mix jewelry, I incinerated for about 2 hours in a coal furnace. Cooled and washed in water. I split it up into two 1000 gram batches and went to work on 50/50 Nitric acid boil for at least 6 hrs, could have been longer ( i used 1ltr D.water and 1 ltr of Nitric for each ) . Cooled, diluted and decanted ( i have filters from Nitric bath, a little bit of black powder and some little foils ) I took what looked like only gold foil mush and put them all into one 4 ltr beaker and started adding HCl (1.5 ltr. )this started to react immediately with a nice yellow color, then after that reaction stopped i added a little heat and started pouring Nitric in 50 ml at a time slowly, reaction started again , but with a total different colour, it was turning greener and greener ( i figured it was a little base metal that didnt dissolve in nitric ) , i decided to go ahead and dissolve everything in AR and deal with it later after i drop with SMB, I ended up decanting first AR batch b/c nothing else was dissolving, so after that i ended up filling about 3 ltrs HCL into beaker and started to dissolve the rest of GF that was left undissolved from first batch, I think i ended up using way too much HCL and Nitric in my AR's. So i finally get everything dissolved out of beaker and leave overnight, I turn up in the morning and see gold precipatants floating on surface of undiluted AR, so I get to filtering that and now i have the stuff thats in the previous post picture. I have moved onto getting the rest of the gold out of AR so i figure i gotta dilute this stuff to SMB it, I take a 1 ltr batch of AR and start adding 3 ltr of water to it the darn thing turns from green to light blue, so i throw some SMB in it and nothing happens, I take same SMB light blue solution and start evaping it and slowly the solution starts to blacken up and drop something out of it. ( i figure way too much free nitric ) so i start evapping AR that has not been diluted to drive out free nitric , i just tried to SMB that and nothing happens, so i dont know if i have to dilute now or evap it again, im so stuck right now.

 

[goldsilverpro]

Your numbers don't make much sense. 2000 grams is 4.4 pounds, most of which (95% - 99% with gold filled) is base metals. One gallon of 70% nitric (diluted to 2 gallons with water) will dissolve about 2 pounds of base metals. Therefore, it would take at least 2 gallons of 70% nitric or 4 gallons of 50/50 nitric to dissolve all of the base metals. You only used .53 gallons (2 liters) of 70% nitric - about 1/4 of what was required. Therefore, you only dissolved about 1/4 of the base metals. That's where your troubles started.

The numbers for 4:1 (80% HCl/20% HNO3, by volume) aqua regia are about the same as for 70% HNO3 with base metals - about 2 pounds of gold and/or base metals per gallon of aqua regia.

 

[jamaicanyute]

For some reason i was working it out that 1ml of 70% Nitric will dissolve 1 gram of base metal. I messed it up for sure by not dissolving all base metals before AR. So lets see if if i got this right, I should evap AR and rid it of all free nitric acid. Then dilute and drop whatevers left with SMB.

 

[Palladium]

Is this part of the same batch that seems to be spread across 2 separate threads?

 

[goldsilverpro]

For some reason i was working it out that 1ml of 70% Nitric will dissolve 1 gram of base metal. I messed it up for sure by not dissolving all base metals before AR. So lets see if if i got this right, I should evap AR and rid it of all free nitric acid. Then dilute and drop whatevers left with SMB.

It takes about 4.1 ml of 70% nitric to dissolve a gram of copper. Silver is about 1.2 ml/gram.

I tried to wade through your posts a couple of times but gave up. At present, is all the metal dissolved?

 

[jamaicanyute]

Yes i know how you feel reading my post, its a mess, hehehe. I got everything dissolved with AR, I have been evapping AR solution about 6 ltrs down to 3 ltrs i added about 2 ltr of HCL and a litre of water to this batch and i am getting a quick yellow flash from stannous test now ( before i was getting nothing, so i feel a little better that i havent fully messed this one up ) . Do you think i should evap it more, or should i be able to SMB it ?

 

[butcher]

cement on copper, study.