How much baking soda to neutralize

[croakersoaker]

Anybody know how much baking soda it will take to neutralize about a half 5 gallon bucket if wast solution which includes copper iron water and an original amount of 130ml of nitric acid? I have used about two pounds so far and it still fizzes when I put more in

 

[Geo]

it will take, well, more than your willing to buy. sodium btcabonate is really for emergency spills or splatters. a more economical choice would be soda ash or lime dust. you can go to your local quarry (if they are mining limestone) and buy a pickup truck load of finely crushed limestone for about $20.00 and have plenty on hand.

 

[notch]

Wally World sells ground Marble (Calcium Carbonate) as Play sand. It comes in different colors but it's all the same. Cheap

 

[goldsilverpro]

Arm and Hammer Super Washing Soda is sodium carbonate (soda ash) and is available cheaply in most grocery stores. As far as neutralizing acids, this works better than baking soda, sodium bicarbonate. The pH of a solution of baking soda is about 9, whereas the pH of the washing soda is about 11.6.

 

[croakersoaker]

Thanks I'll try that have now put five pounds of baking soda still need more. You mentioned the ph of a solution. Should I be making a solution, I have been sPrinkling the powder right in the bucket.

 

[eeTHr]

croakersoaker---

You should check the "Waste" link, below.

 

[goldsilverpro]

Just sprinkle in a little powder. Let it fizz. Stir a bit. Sprinkle in more.\

In solution, that's what the pH would be. The higher this pH, the more acid it will neutralize. You're putting it into solution when you add it to the acid.

 

[croakersoaker]

Thanks

 

[goldsilverpro]

croakersoaker,

Forget what I said earlier about the carbonate. For some stupid reason, I was thinking about the old days when we could get away with just about anything. Those days are gone. If you are treating these for dumping purposes, the only way that straight neutralization would be legal would be if the solutions were purely acids with no metals dissolved in them.

When you neutralize an acid solution containing copper, nickel, or other metals, you end up with metal carbonates or hydroxides (if NaOH is used for neutralization), etc. These are very voluminous, extremely difficult to filter, and, as far as the EPA is concerned, they are still hazardous waste. In other words, you haven't achieved anything and have just converted a liquid form of hazardous waste to a more difficult to treat solid form of hazardous waste.

I would strongly suggest that you study 4metals posts in the following thread and follow his procedure.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=47&t=1300&hilit=treatment+wastes

 

[croakersoaker]

Sorry I thought you understood it has been sitting for a week with iron or steel wouldn't that cement out the metals then neutralize the acids and disPose of

 

[Geo]

cementing with steel doesnt neutralize the acid. the steel just replaces other metals thats higher on the reactivity scale.

 

[goldsilverpro]

Sorry I thought you understood it has been sitting for a week with iron or steel wouldn't that cement out the metals then neutralize the acids and disPose of

So now you have a solution containing dissolved iron. If you neutralize the solution with sodium carbonate or NaOH, a very difficult to filter iron compound will precipitate. As 4metals suggested, if you use magnesium hydroxide to neutralize the solution, the iron compound will filter much easier. After filtration, the neutralized acid solution, with no solids in it, can be disposed of. Before disposal, though, the pH must be in a certain range. I don't know what this range is, but I would guess it's between 5 and 9. If it's out of range, you can use either a base, such as sodium carbonate, to raise it, or HCl to lower it, depending on whether it's too low or too high (most likely). It will probably take very small quantities of either to get it into this range, so go easy on it.

If ALL of the heavy metals (copper, nickel, etc.) have been cemented out by the iron, as metal powders, and removed from the solution before neutralization, I think the filtered iron hydroxide solids, as obtained by neutralization, can be disposed of. If the iron hydroxide is contaminated with heavy metal compounds, it cannot legally be disposed of, unless you hire an authorized waste hauler to haul it off.

Do everything in order, as per 4metals' suggestions, and you should be OK.

 

[croakersoaker]

So what your saying is I can not do everything in one bucket that I have to seperate out the copper powder before I neutralize the acid

 

[goldsilverpro]

So what your saying is I can not do everything in one bucket that I have to seperate out the copper powder before I neutralize the acid

Absolutely

 

[qst42know]

So what your saying is I can not do everything in one bucket that I have to seperate out the copper powder before I neutralize the acid

Yes, dedicate a bucket for each. Three buckets work well, drop PMs with copper in one it should be kept very clean. Scrap iron can be left in the copper drop bucket. And the last for the lime, that ends up looking like rusty plaster.

 

[croakersoaker]

Just one more question, 4metals mentions raising the ph to 2.5 before adding the iron. Is this step absolutely necessary and how do get the ph at exactly 2.5 or does it just need to be close?

 

[croakersoaker]

So what your saying is I can not do everything in one bucket that I have to seperate out the copper powder before I neutralize the acid

Yes, dedicate a bucket for each. Three buckets work well, drop PMs with copper in one it should be kept very clean. Scrap iron can be left in the copper drop bucket. And the last for the lime, that ends up looking like rusty plaster.

I already dropped pms (recovered silver)with copper after nitric digestion so I can go straight iron right?

 

[Nickpearl]

Regarding pH levels, how can I measure pH?
Should I buy a waterproof pH tester? Should I use paper strips?
I can add potash or baking soda until the fizzing stops, but as I try to remove copper with iron I need to assure the pH is up to 2.5.

I do not use Urea on AR, I evaporate under heat, then add Sulfuric, then evaporate, then add HCL. Then dilute, filter (sometimes twice) then drop with SMB.



Thanks

 

[qst42know]

I don't think the PH is critical if you have plenty of scrap steel. If a clean piece is added and no copper cements you should be good to proceed.

A meter or test strips for neutralizing keeps you from wasting lime.