# Catalytic Converters - Hard to find answers



## Kalahari_Harry (Sep 22, 2013)

Hi, I am a young Engineer in South Africa, trying to figure out the whole process, as it is extremely difficult and expensive to send "Cats" from South Africa to Umicore in Belgium or BASF in UK. I have access to about 2000 good quality "CATS" per month and saw great potensial in refining them localy. I have therefore purchased Steve's DVD for Refining Platinum & Palladium, and I am truly impressed by his knowledge and skills. It is a definite "must buy" for any novice like me. However I do have some questions and would sincerely hope that any of the "Wise men" can assist me in finding answers to my questions, being:

1. The suggested "brewing" time for best extraction of PGMs from crushed catalytic converter honeycomb in diluted AR heated at 70 degrees C(25kg honeycomb, 4.5ltr HCL, 1.5ltr HNO3 and 10ltr H2O)? (Currently 3 days)
2. The amount of Ammonium Chloride per estimated gram of Pt?
3. After precipitating Pt or Pd, I end up with say 15gr Pd(brown crystals/salts) but after calcination the final grey Pd product will only be 1-2gr, why is that? I do test the white fumes for any discolouring.
4. After Denoxx and Zinc cementation of PGMs, I find alot of Zinc sludge in my filter after decanting. I have tried to add extra HCL but then it seems as if I have less Black PGM particles as it is absorbed/converted by the HCL, please assist?
5. Will using Urea, to improve denoxing Nitric Acid from the 16ltr liquid mixture(PGMs + HCL + H20 + HNO3) have any consequences? What are they?

I appreciate the effort made by everyone on this forum, and would like to thank LaserSteve, HaroldV, Lou act.

A friend in need,
Kalahari_Harry :lol:


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## butcher (Sep 23, 2013)

To get all of the answers, you will need to study.

Several leaches with fresh acid solution will work better, than just one prolonged leach.
Stirring of powders would also be important as to how well the acids can leach.
How the acids are added as well as temperature and concentration,can also be a determining factor in their effectiveness in leaching.

Urea would not help actually it would do much more harm than good, especially where PGM are concerned, it can form complexes with the platinum group making it even more difficult to recover the metals as you normally would.

Test your solutions to see when you have precipitated all of the metal you can with the NH4Cl.
With precipitating PGM you just cannot get all of it to precipitate, this is where the stock pot acts like a piggy bank.

Metal salts contain the metal cation and the (acid or complex) anion, when melted (or calcined), you drive off the anion, which can account for some lose of weight.

It normally takes more weight of the metal salt to equal the same weight the metal melted would have if calcined or melted.
I cannot comment on the ratio's but these can normally be found with searching.

When you say you precipitate brown salts of the platinum group (this sound like they are not pure), the platinum ammonium chloride ("Orange powder") should be yellow to orange which could also count for lose or weight lose.

some of the platinum group are soluble in water, for this reason we do not wash the 

You can also loose metals in fumes when calcining or melting, many times this depends on the state or conditions and the procedures used.

Hoke's book states to precipitate platinum from aqua regia, for each quart of solution will need about a half a pound of ammonium chloride, dissolved in hot water (to make a concentrated solution), use plenty; for each penny weight of platinum that is in solution , you will need a little over 1/2 penny weight of ammonium chloride, and a little excess.

Cementing with zinc can cement most all metals below zinc in the reactivity series of metals (this could include iron). 

Concentration, and temperature can be a factor when precipitating platinum from solutions.

Others here have much more experience with the platinum group than I do, I find it hard to get my hands on much of it.

Have you read Hoke's book yet?


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## samuel-a (Sep 24, 2013)

Unfortunatlly, there's very little (to none) economical value for processing spent CC honeycombes by wet means.
Recovery rates are too low compared to labor cost, chemicals + utilities, metals turnaround time and waste treatment. To make this work, you will need a very tight operation.... (or very very cheap scrap)

However, CC beads and other PM bearing packing materials can and are indded being processed commercially by wet leaching. I have heard that In some cases, the processed beads receives a new coating and are re-sold as new product. That's a true win/win.

Now assumeing you do have crushers + inciniration units and a large arc furnace and you learn how to smelt and refine the metals and still produce some profit, you are still in a big disadvantage compared to the big-boys as they do not just sell the refined metals as is. They produce added value products out of it and sell it for way above the fixed prices. Slag is usually sold to cemet factories and road paving companies.

Not trying to discourage you here, just letting you know the reality of this business as it is and maybe save you from a lot of grieve.
Personally, i wouldn't base any business plan on in-house processing of cat's and other low grade (PGM < 1% w/w) PGM bearing scrap.
But who knows... Maybe you are creative enough to actually make it work... In that case, i wish you all the luck in the world.


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