# Cleanest way to neutralize



## banjags (Mar 11, 2008)

I recently neutralized a batch of AP. I used baking soda... what a foamy frothy mess. Is there a chemical that will neutralize without causing such a mess or is it just the chemical reaction and no much can be done about it. 

After AP has been neutralized and metals dropped out is this safe to go down the drain?


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## Gotrek (Mar 11, 2008)

Muriatic acid, pour it on the driveway to get the oil stains out.  kidding.


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## peter i (Mar 11, 2008)

Baking soda and acid will release carbon dioxide and leave the sodium salt of whatever acid you neutralize. If your solution has the ability to foam, it will be messy.

Baking soda is a weak base, and totally harmless (that’s the nice part).

If you use a stronger base like sodium hydroxide, the will be no gas evolved, but you will have a significant heat, the risk of sudden boiling and the dealing with a very corrosive chemical. (Until neutralized, then it’s the same end product as you get from using baking soda)

In Denmark a saturated (pure) NaOH solution is sold as a drain-cleaner. It is very nice for a lot of purposes, and causes a few serious accidents every year.


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## goldsilverpro (Mar 11, 2008)

When you neutralize an acid solution that contains heavy metals, you end up with metal hydroxides or metal carbonates. In the EPA's eyes, these solids are still hazardous waste, based on their method used to test them. Also, these are difficult to handle. They are very voluminous and are hard to filter and dry. They can feel dry in your hand and still contain 75% water.

I would suggest first, before neutralizing, that you cement the metals, AS METALS, using another metal that is higher on the electromotive scale, such as iron or aluminum. The results would be metal powder and a solution containing Al or Fe. Then, after removing the powders (rinse them well and prevent oxidation), you could neutralize the solution. You end up with Al or Fe carbonates or hydroxides, which are considered much less hazardous. They will, unfortunately, also be difficult to handle.


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## banjags (Mar 11, 2008)

What can be done with the left over liquid? once neutralized


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## Lino1406 (Mar 21, 2008)

It is assumed (that can be checked out)
that the soluble metals include Ni, Cu, Sn, Fe.
The optimal preciitation PH = 9, this you can
achieve with baking soda or soda ash. The
sludge formed should be press filtered. The
liquid, if standing local standards, can be
discarded.


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## Anonymous (Mar 21, 2008)

Banjags have you purchased C.M Hokes book on Precious Metals Refining.

If not you can pick up a copy from the Gesswein , Canadian sister company only $60.25 plus $12.00 shipping.

Their toll free number is 1-888-944-0909 ask for Brett in the Toronto Branch.

Ask for Item BKS538, this is Hokes in Hard Cover.


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## eagle2 (Mar 23, 2008)

banjags said:


> I recently neutralized a batch of AP. I used baking soda... what a foamy frothy mess. Is there a chemical that will neutralize without causing such a mess or is it just the chemical reaction and no much can be done about it.



I would suggest an easier method, (a little slower) is to evaporate the AP solution to a small amount of liquid and then dilute back to a suitable amount.

This will get rid of the excess HCl. You will also get rid of all of the Peroxide, which may interfere with the next step of precipitation. A good side result is that your Gold in solution will be more concentrated and precip better and be MORE complete.

If you are now going to use SMB, all you have to do then is make minor adjustments with Bicarb. and check that the PH is about 1 to 3.

Al


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## eemtek (Apr 16, 2008)

I have a 500 gal tank. I have a small 15 watt powersupply fan that continuously flows across the top that is always open.. The top is around 6ft giving it approx 28 sq ft of surface area to evaporate. I find it to release chlorene, water, and sulfur dioxide, but in tolerable amounts.. With this much surface area, it averages 10 gallons of loss per day almost double when its really warm.. The main idea is to condense the metals and salts. You cannot catch all the precious metals, but whats on the bottom of the barrel is of value to any refinery.. even copper, nickel, etc.. Please dont ask me which refinery, I have not found one yet that I can trust, thats why we are here.. every once in a while I just dry out the barrel and add to my drum of old slag.. You will find most of precious metal refiners even have places they send their slag to recover all the metals.. :idea: Just you need 40k lbs at a time to ship or trust a refiner at the current time?

Just make sure if you do this, it is set up where no one will mistaken it for a swimming pool :shock: 
there is also a guy I met in el paso tx that makes a unit that holds and recovers over 5 gallons of water/acid per day.. i have one, but just dont have the time to keep filling it.. You can actually reuse the water that has some dilute acid. you could find it on the internet by maybe looking up solar water filter? I know he has a website, but I only know where his shop is..

hope this helps..


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