starting catalytic converter test with pics

[kjavanb123]

You are using way too much HCl and nitric. Try covering the comb in tap water then add enough AR (5:1 HCl:HNO3 muriatic:nitric) to dissolve about five grams of PGMs (25mL HCl : 5 mL HNO3). Double the amounts if you are processing cats from high end foreign model vehicles. I usually use more HCl than 5 times the nitric so the solution is a little more acidic. You can double or even triple the amount of HCl, but not the nitric and still get good results.

Add the nitric in 1-2 mL additions at 60-90C and stop adding if you don't see any tiny bubbles coming from the material with each added dose. The crushed material has to be stirred also to expose the fine grains to the acid. You should notice the color of the solution darkening as the PGMs are extracted. Test periodically with stannous chloride and DMG to monitor the reaction progress.

Steve

Steve,

Is this ratio of acid good for honeycomb or just bead? I thought to extract Pt and Rh one needs more concentrated AR?

Thanks
Kev

 

[lazersteve]

The ratio of HCl to HNO3 and the solution concentration are two different aspects of the reaction.

The ratio is the amount of each reagent that is in the solution with respect to one another, the concentration is the ratio of these reagents to the overall solution volume which is made up of water in aqueous reactions like AR.

The amount of water is what determines the concentration of the solution, the amounts of HCl and HNO3 determine the ratio of the reactants. With dilute solutions the ratio of HCl to HNO3 is the same as with concentrated solutions, the only difference between concentrated and dilute is the amount of water present.

Steve

 

[kjavanb123]

Opps,

Then I added way tooo much muratic to my honeycomb, almost 2liters of HCL and 400cc HNO3 added whilte HCL was heating. Let me get this straight, if I wanted to do this I would have used 2 liters of tap water, 50ml of HCL and 10mlHNO3?

Thanks
Kev

 

[lazersteve]

I would split the water and HCl, using more HCl, less water, but the same nitric acid.

You can also use the same AR solution over and over again for several passes through several combs until the solution becomes saturated enough to warrant the clean up process.

So for your two liter scenario:

1000 mL of HCl, 100 mL of HNO3, 900 mL of water will do 10 cats processed one after the next in the same AR. Gentle heating is required.

You'll find that HCl-Cl is more economical and can be just as effective if the reaction is driven properly (plenty of agitation/stirring). For the same scenario (2 Liter reaction) above you would have:
1000 mL HCl, 1000 mL H2O, NaClO added as needed in 25-50 mL increments with stirring to produce chlorine.

Add more bleach only after the solution no longer fizzes when stirred, or until the color of the stannous test swab no longer get any darker after sitting for several hours. This reaction works fine in the cold as well as at warmer temperatures below 60C. I prefer to use it in the cold.

Steve

 

[kjavanb123]

Steve,
well noted, and very well explained. Once i finished processing 10 cats, I would like to donate 10 grams of PGMs to your site for your helpfull tips.
Thanks
Kev