# nitric removal



## kjavanb123 (Apr 9, 2011)

All,

I have posted something about my home-made PGM leaching system with pics under Equipment section, the AR solution i got from that system, had dissolved some brass along with Pt. I added soda ash till the pH was 3 then added zinc, but brown fumes formed after each addition and no signs of PGM black powder, I assume that is from the nitric in the solution, is there any alternatives to avoid the steam bath the solution to remove the nitric? cuz PGM solution with nitric takes a lot more zinc to push out the pgm

Thanks
Kev


----------



## Barren Realms 007 (Apr 9, 2011)

You should add your soda ash till the color of your solution starts to clear and then add you zinc. Are you sue you still have PM's in your solution? The zinc in the brass of the impeller could have cemented out your PM's.

It woud have been a good idea to keep this question with your other thread.


----------



## Harold_V (Apr 10, 2011)

Barren Realms 007 said:


> Are you sue you still have PM's in your solution? The zinc in the brass of the impeller could have cemented out your PM's.


While it's true that zinc would do as you said, it's also true that everything in the pump that was exposed to the acid solution would do the same thing. That includes the housing, assuming it's cast iron. Any copper alloy would cement values. There should be NO metals exposed when circulating AR. 

Harold


----------



## Barren Realms 007 (Apr 10, 2011)

Harold_V said:


> Barren Realms 007 said:
> 
> 
> > Are you sue you still have PM's in your solution? The zinc in the brass of the impeller could have cemented out your PM's.
> ...



On the type of pump he is using that he showed in his other post the housing is usually brass not cast iron.


----------



## Harold_V (Apr 11, 2011)

Barren Realms 007 said:


> On the type of pump he is using that he showed in his other post the housing is usually brass not cast iron.


Needless to say, it makes no difference. It, too, is just a brief instant from being totally destroyed by AR. Metals of any description (that are likely to be found in pumps) are to be avoided when pumping acids. 

Harold


----------



## Platdigger (Apr 11, 2011)

I have a large neumatically powered parastaltic pump if anyone is inerested.


----------



## Lou (Apr 11, 2011)

These new Wilden pumps are supposed to be great.

As they're using a PTFE diaphragm and wetted PTFE parts, there aren't many compatability issues to be concerned with.

Can usually be had quite cheap on eBay too.

http://www.wastewaterpr.com/releases/view/1283/Wilden-Introduces-Full-Stroke-PTFE-Pump-Diaphragms


----------



## kjavanb123 (Apr 11, 2011)

in regards to the PGM solution that got mixed with brass dissolved in AR, I cement everything with zinc and produced the metallic Pt powder. I am going to leach the 4 cats using an acid-resistance pump, this method is saving big on zinc usage since AR used is only 1.2 liter.

The other PGM solution when adding zinc produces a brown fume which is nitric. I am gonna try to steam bath the AR solution and add HCL to replace the nitric.

Thanks
Kev


----------



## Barren Realms 007 (Apr 11, 2011)

Lou said:


> These new Wilden pumps are supposed to be great.
> 
> As they're using a PTFE diaphragm and wetted PTFE parts, there aren't many compatability issues to be concerned with.
> 
> ...



These are about the most reliable when dealing with acids. The only draw back to them is being able to regulate the flow of fluid thru the pump because it is not a contanst presssure with the diaphrams going back and forth. But for pumping reliability they can't be beat. The PTFE diaphram is not really new to the industry, they were available 15 years ago when I used them on a constant basis. One of the problems we use to run into with them was the air ram use to stick on them, I use to solve the majority of this problem by taking some sand paper cloth and sanding the ram down a few thousandth's to give a little less tolerance in the ram. Transmission fluid was the best lubricant we found at the time to keep the piston lubricated. Very durable pumps tho.


----------



## Alquimi (Apr 13, 2011)

Hello;

When you have this problem of nitrogen vapor, usually dilute my solution of RA in 9 parts water, then add the reducing agent.
Particularly not use Zn precipitates as many base metals.

Alquimi :?: :?:


----------



## Platdigger (Apr 21, 2011)

Hey glondor, it is a Randolph model 880. For some reason I have not been able to send PMs of late.


----------

