# PGMs precipitation question



## kjavanb123 (Jun 8, 2012)

All,

Instead of precipitating the mixed PGMs using zinc after it was leached then refine the mixed black powder, can we just add ammonium chloride saturated and sodium chlorate? would that work?

Thanks and regards,
Kevin


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## Geo (Jun 8, 2012)

im sure you've heard this before, be very careful using ammonia when refining. if you add ammonia to anything, be sure its in its elemental metallic form and not dissolved in solution. always make any solution you have added ammonia to acidic before you stop working for the day. if a solution containing dissolved metal and ammonia dries, it becomes VERY volatile and can explode with no outside influence.


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## samuel-a (Jun 8, 2012)

Kev

The dilution and oxidizing nature of your leach will prevent any meaningful precipitation.


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## kjavanb123 (Jun 8, 2012)

All,

Thanks for your responses. Following questions have raised.

1. Is the zinc powder from AA or AAA batteries usefull for zinc precipitation?

2. How many times the AP that was used to leach numbers of converters can be reused to leach another 
Converters?

3. Palladium once dissolved in nitric from mixed black powder, should nitric be removed using Urea
Or evaporation before dropping the Pd using SMB?

4. Is there any chemical ways to convert yellow canary Pd salt to gray metallic form and avoid calcining?


Thanks and regards,
Kevin


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## Oz (Jun 8, 2012)

Using zinc concentrates your values and allows you to then clean them up and precipitate from concentrated small solutions. You can also just sell them as a mixed PGM sponge on assay. No more chemistry needed, and no additional toxic salts.


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## lazersteve (Jun 9, 2012)

kjavanb123 said:


> All,
> 
> ...
> 
> 1. Is the zinc powder from AA or AAA batteries usefull for zinc precipitation?


No, it contains other impurities related to the operation of the battery that are not desireable in your Pt. Pure zinc turnings produce the best PGM black in my opinion. You can buy the zinc turnings from my website store (link below).



kjavanb123 said:


> 2. How many times the AP that was used to leach numbers of converters can be reused to leach another
> Converters?


 Generally speaking you can dissolve about 1 gram of PGMs in 5-10 mL of the AP solution depending on the dilution of the AP solution. Unfortunately you can not cover the raw honeycombs with this small amount of solution and affect recovery. Therefore you must use the solution until it's stannous test will no longer darken in color. Three to five extractions before adding zinc turnings is a good baseline number.



kjavanb123 said:


> 3. Palladium once dissolved in nitric from mixed black powder, should nitric be removed using Urea
> Or evaporation before dropping the Pd using SMB?


 Evaporation to remove the excess nitric is not necessarily required if there is no Pt in solution. Instead add HCl (3 moles per mole of Pd present) followed by a saturated potassium/ammonium chloride solution. The Pd solution must not be too dilute before adding the KCl/NH4Cl for this to work. 



kjavanb123 said:


> 4. Is there any chemical ways to convert yellow canary Pd salt to gray metallic form and avoid calcining?


 Yes. You can use either hydrazine and a base or zinc turnings and an acid. Here's a detailed post of the zinc process.

PGM Sponge without Calcining

and a few more snapshots of some hydrazine sponge:

Hydrazine Pt Sponge Snapshots

Steve


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