Making "Copperas" - ferrous sulphate

Copperas - is an iron salt, chemical name ferris sulphate. In Hoke's book on pg. 64 it says one way to make it is to dissolve iron in sulphuric acid, then crystalize out the salt that forms.
I cut up some cast iron scrap, put them in old cast iron frying pan, mixed
up some dilute sulphuric acid , covered the pieces in pan. It went to work right away. Started to stink real bad like rotton eggs. Stank up my whole shed! It stank for two days straight! Managed to clean frying pan really well before I gave up due to smell!
I read somewhere else to make away from light. Does anyone know a proper way to do this?

Thanks
Wayne

Ferrous sulfate (copperous) also called green vitriol.used to precipitate GOLD.
I make mine by putting dilute sulfuric acid glass jar, take transformer laminates (IRON) burn of surface contaminate, rinse,cut to small pieces put in jar of H2SO4, let disolve (can heat if in hurry),solution looks light green and metal Iron in bottom is good.
I keep slightly acidic if storing.
{do not stopper as gasses would build preesure causing potential dangers},adding a little sulfuric acid or iron pieces as needed and to keep acidic,
this can be decanted and used to precipitate gold or evaporated to copperous salts (pale green yellow)for long term storage.
this makes a very good chemical to precipitate Gold chloride from solutions and doesn't seen to drag down the copper(from high copper solutions) like sodium metabisulfite does.

I just tried making Ferrous sulfate (copperous) but I did not get a green reaction. My steel is disolving very slow and the acid is a light brown.
I cut the Sulfuric about 50/50 with water. It's been more than a week and my steel is still in pretty good shape. I used strips of sheet metal and expected them to disolve rather readily.
Am I doing something Wrong?
John

John,

I use the crystal that form in my silver chloride reduction setup. The acid is between 5-10% and slowly (1 week) dissolves the iron and forms nice big green crystals in the bottom of the flask. I'll post some photos when I get home tonight.

The copperas crystals is just a by product of the silver chloride reduction for me. Depending on how long you let the solution sit, you can grow some very large crystals.

Steve

The rotten eggs reek is from sulfide impurities in your iron source.

Ideally, you should use just pure iron and dissolve in hot dilute sulfuric acid.

Lou

Lou provided some excellent advice. Cast iron that was created in a cupola will generally have a fairly high sulfur content due to the sulfur content of the coke used. I would suggest you avoid using cast of any description for that reason.

Steel, particularly mild steel, such as angle or channel iron, is low carbon, under .2%, and low sulfur as well, so it is one of the more desirable sources. The best one is laminations from transformers. They are made of carbon free iron, as are laminations in motors.

I would think that filtering the resulting solution before allowing the crystals to grow would be adequate to remove traces of carbon.

Harold

Electricity will help it dissolve quicker.

I was fooling around with a citric acid and potassium persulfate electrolysis cell, and had a copper and iron anode. I let it run for a quite a while to see if anything would happen, nothing much did. Then it sat there for a couple weeks and when I went to clean it up, the copper pipe was half transformed into copper sulfate crystals. It looked cool, copper at one end and big blue crystals on the other end.

so can napa acid be used out of the box without dilluting?

NAPA acid ?
if by napa acid you mean sulfuric battery acid, it can be used for ferrous sulfate,
if you want to concentrate sulfuric battery acid it can be done by boiling till white fumes appear(approx98%)
never use used battery acid,

Yeah, what butcher said. Used acid can contain traces of lead (sulfate), which is death on the quality of gold.

In order for the ferrous sulfate crystals to grow, you may have to condense the solution until it nears saturation.

The acid can certainly be used dilute, and is actually preferred. For example, slimes from silver cells were commonly boiled in cast iron kettles in concentrated sulfuric acid to recover the silver that was enclosed. The sulfuric had little effect on the iron unless it was diluted.

Lou or Steve could better advise you on growing crystals. What little ferrous sulfate I used was purchased, some even from a gardening center. I preferred SO2 from a cylinder, but ferrous sulfate works well, too.

Harold

was just wondering since the napa sufuric acid was already dilluted ,and definately use new acid in this process.

So do we rince ,dry or use the crystals as is ,

ferrous sulfate, if crystals I add water and few drops sulfuric to make sure its a little acidic (I have read where some people add few drops of HCL to get acidic).
I have used it without making it into crystals, and I only make the crystals if I want to store some of it.

Steel freight banding is low in impurities. The black finish burns off quickly. And coiling it around a pair of needle nose pliers removes most of the heat scale. An equal weight of banding provides a great deal of surface area to the acid and it dissolves pretty quickly.

What is it about cementing silver that dissolves iron so much faster though?

Would a small amout of HCL speed things up?

The only reason I mentioned the silver chloride conversion relevance is because the ferrous sulfate is usable by product of the reaction. It's always nice to have uses of the leftovers of a reaction.

Many of the left overs from silver reactions lend themselves to recycling and/or reuse.

Steve

Just wondering what the by product of dissolving motor laminae in the dilute sulfuric is besides copperas? Fumes? Will the reaction still continue in the cold, just slower? I'm talking 20 degrees below F.

I would guess if your car battery doesn't freeze in such weather, you could try it.

As the acid gets used up it may freeze, (just guessing here) and I suspect it will take a long time. Time may take the place of heat.

I would not try this in glass but in a plastic container set in a larger bucket in case it freezes and splits. I may try this myself though I don't have 20 below.

A battery that is not fully charged will freeze,
so I would think that fresh acid not used in a
battery would probably freeze. The reaction
should build up some heat, don't know if it
would be enough to keep it from freezing.
It is cheap enough to just try it out, as long as
you use a container that won't break.
Jim

qst42know said:

I would not try this in glass but in a plastic container set in a larger bucket in case it freezes and splits. I may try this myself though I don't have 20 below.

Click to expand...

Plastic buckets at such low temperatures are no better than glass.

Harold

You may want to take a look at this link. It has the freezing points of sulfuric at different concentrations. http://www.resistoflex.com/sulfuric_graphs.htm

Randy