yacht252002
Member
- Joined
- Dec 25, 2016
- Messages
- 22
I am working on adding the Platinum and Palladium refining into my current Au&Ag refining process these days, and I have a few questions about the purification of platinum.
My materials are usually Gold 50%, Ag 10%&lower, Pt/Pd, a lot of copper
My steps are:
1. Aqua regia dissolving, remove Ag.
2. SO2 drops the gold.
3. Check the solution by ICP to see if any leftover gold, and find out the range of Pt/Pd (usually around 1000-6000ppm)
For the Pt/Pd refining, I basically followed the “Refining Precious Metals Wastes by CM. Hoke” book by the steps below:
1. Add NH4Cl powder to the solution, based on 1g Pt/Pd with 2g NH4Cl.
2. Let the precipitate (Pt salt) settle down, remove the supernatant (solution A) for Pd refining.
3. Purify the yellow Pt salt.
4. Add sodium chlorate to solution A to drop out Pd
5. Purify the red Pd salt.
Now my questions are:
1. After I get the yellow Pt salt, I use NH4Cl solution (3g NH4Cl in 600ml) to wash several times, then filter the salt and put them in the furnace to make Pt powder. The problem is I have to do this purification at least 4-5 times in order to achieve the 99.95% purity, but based on the Hoke book, it could be done by 2 times. Are there any tricks at washing?
2. I tried to wash the Pt salt with the NH4Cl solution more to reduce the refining cycle number. It looks like helps a little bit, I can drop the cycle from 5 times to 3 to 4 times to reach 99.95%. But I noticed that more and more Pt lost with the wash, if I do 5 times wash for each refining cycle, I could lose up to 20% of Pt per refining cycle. For example, for one experiment, I used pt salt which should have 3.4g of Pt at the beginning, after the first refining cycle, the Pt powder is only 2.7g. This number was down to 2.1 after the second cycle and finally to 1.7g at the end of the third cycle. I did notice that every time the washing solution becomes yellow in color, and I know there will be always a loss but I am not expecting that much. How to decrease the amount of the lost Pt in order to increase the refining rate?
3. This is the NH4Cl that I bought:
https://www.amazon.com/Alpha-Chemicals-Ammonium-Chloride-NH4Cl/dp/B004V9UQ14/ref=asc_df_B004V9UQ14/?tag=hyprod-20&linkCode=df0&hvadid=167139575215&hvpos=&hvnetw=g&hvrand=14257485731252429006&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9005444&hvtargid=pla-306024084888&psc=1
I noticed that when dissolving them in DI water, the solution looks a little cloudy(white), as I understand it means the NH4Cl is not pure enough that I need to filter it. But will that affect a lot to refining process?
Thanks
My materials are usually Gold 50%, Ag 10%&lower, Pt/Pd, a lot of copper
My steps are:
1. Aqua regia dissolving, remove Ag.
2. SO2 drops the gold.
3. Check the solution by ICP to see if any leftover gold, and find out the range of Pt/Pd (usually around 1000-6000ppm)
For the Pt/Pd refining, I basically followed the “Refining Precious Metals Wastes by CM. Hoke” book by the steps below:
1. Add NH4Cl powder to the solution, based on 1g Pt/Pd with 2g NH4Cl.
2. Let the precipitate (Pt salt) settle down, remove the supernatant (solution A) for Pd refining.
3. Purify the yellow Pt salt.
4. Add sodium chlorate to solution A to drop out Pd
5. Purify the red Pd salt.
Now my questions are:
1. After I get the yellow Pt salt, I use NH4Cl solution (3g NH4Cl in 600ml) to wash several times, then filter the salt and put them in the furnace to make Pt powder. The problem is I have to do this purification at least 4-5 times in order to achieve the 99.95% purity, but based on the Hoke book, it could be done by 2 times. Are there any tricks at washing?
2. I tried to wash the Pt salt with the NH4Cl solution more to reduce the refining cycle number. It looks like helps a little bit, I can drop the cycle from 5 times to 3 to 4 times to reach 99.95%. But I noticed that more and more Pt lost with the wash, if I do 5 times wash for each refining cycle, I could lose up to 20% of Pt per refining cycle. For example, for one experiment, I used pt salt which should have 3.4g of Pt at the beginning, after the first refining cycle, the Pt powder is only 2.7g. This number was down to 2.1 after the second cycle and finally to 1.7g at the end of the third cycle. I did notice that every time the washing solution becomes yellow in color, and I know there will be always a loss but I am not expecting that much. How to decrease the amount of the lost Pt in order to increase the refining rate?
3. This is the NH4Cl that I bought:
https://www.amazon.com/Alpha-Chemicals-Ammonium-Chloride-NH4Cl/dp/B004V9UQ14/ref=asc_df_B004V9UQ14/?tag=hyprod-20&linkCode=df0&hvadid=167139575215&hvpos=&hvnetw=g&hvrand=14257485731252429006&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9005444&hvtargid=pla-306024084888&psc=1
I noticed that when dissolving them in DI water, the solution looks a little cloudy(white), as I understand it means the NH4Cl is not pure enough that I need to filter it. But will that affect a lot to refining process?
Thanks