Is my Copperas screwed!

I have bought 1 bag 35kg of Ferrous Sulfate from my supplier. After I have complained that it is oxidized, they shipped me another bag for free, saying it is from new batch.

The problem I have is that there is about 2-3% of Ferric Sulfate (white-yellow sediment) in my Ferrous Sulfate.

Butcher, I know you are "Copperas Guru", counting on your advise!

I have previously followed your advise and sprayed "spoiled" Copperas with weak H2SO4. Did I unadvertantly created Fe2(SO4)3?

According to Wiki (I do not fully trust)

2FeSO4 + H2SO4 + H2O2 → Fe2(SO4)3 + 2H2O

or instead of H202 one molecular of Oxygen will create the reaction on small scale, am I wrong?

Again, Wiki states: "Usually yellow, it is a rhombic crystalline salt and soluble in water at room temperature" and at the same time on the right side it said "Solubility in water - slightly soluble"

When I dissolve my copperas in water and add drop of HCl it is normal green color. When I wash the beaker with hot water after copperas use, I always notice that it it turns yellow-brown, that is the sign of Ferric Sulfate being dissolved. Made me always wonder, now I know.

Is there any way to get rid of Ferric Sulfate from Copperas?

Ferrous sulfate,Iron II sulfate, FeSO4, Fe+2, copperas, green vitriol, is a green solution, which can be made easily with dilute sulfuric acid (10% H2SO4 and heat) when evaporated slowly keeping it acidic, we can make light green crystals to test for gold in solution, or precipitate gold from solution.

FeSO4 ferrous sulfate can oxidize to form ferric sulfate, this can be from storing dry crystals in air, or from a strong oxidizer like hydrogen peroxide, nitric acid or chlorine, other iron oxides also normally form during this reaction.

Ferric sulfate, Fe2(SO4)3, Fe+3, Iron III sulfate, can be yellow to brown in solution, or look whitish dried, It will not test for gold or precipitate gold.

if even a portion of your copperas (ferrous sulfate) is oxidized to ferric sulfate I would not use it you will contaminate you gold, the iron salt ferric is only slightly water soluble so it would take a lot of washing to remove contaminate, left in with the powders I do not know if it would reduce the iron when you melted your gold, but iron will amalgam with gold, so I am not sure if this would give any trouble or not.

It is so easy to make a big batch of copperas, why try to mess with inferior products, if you can get good copperas cheaply that may be different, but if the crystals did not look like those in Wikipedia for copperas (ferrous sulfate) pretty light green crystals, then I suggest just make your own, I do not know of any way to reduce ferric sulfate back into ferrous sulfate (besides maybe making back into iron and starting over).

I have given details how to make the pretty green crystals of copperas and how to store them, it is easy, in one afternoon, or maybe two, you can make a big batch to last you some time.

Some metals just seem more complicated to me in chemistry, Iron for me is one of those metals.

Maybe someone else know how to get the ferric back into a ferrous?

Butcher, thank you for your reply!

I need large quantities of Copperas. I have tried to make it two times and for the amounts I need, it i will take too much time and space and both I do not have enough.

While I was driving home from the the office I was thinking...

Only small amount of Ferric Sulfate enters the solution due it's low water solubility. I let Copperas solution sit, so powder settles before I pour it into into pregnant solution.

My mistake was to warm up Copperas solution previously and letting more Ferric Sulfate to enter the solution. Today I was doing it cold (room temp) using only stirrer.

Normally when thrown into Auric Chloride whatever Ferric dissolved should remain dissolved.

Even if small bit of Ferric Sulfate drop down with gold, boiling water washes should get rid of most of it.

Going back to my observations washing beaker used for Copperas, hot water turns any sediment right away into yellow-brown water. So it is obviously more soluble in hot water.

I think I rang false alarm, but in any case, there is always something to look for.

Eventually, I do second refining with Oxalic and that removes any last traces or anything else. When I melt my Oxalic refined gold it is amazingly bright and shiny without a single tint of any other metals present.

I am not sure if converting Ferric to Ferrous is possible. You have to steal that Oxygen molecule from Ferric.

If your ferrous is not too oxidized (too much of it converted to ferric) you probably can dissolve it in minimum water (I would probably try and add a little bit of H2SO4to keep it acidic) let it sit to settle well, and decant and filter, my thinking here is limit the volume of liquid, so not all of the ferrous dissolves, helping to keep the ferric from going into solution as little as possible, it is less soluble, then filter and re-concentrate the ferrous solution back toward crystallization, keeping acidic, the ferrous crystals should form as more pure crystal.

I tried to find good copperas at the garden supply places, every time I bought it, and opened the bag it was always oxidized brown white to ferric and iron oxide, I just gave up and started making my own.

you should be able to find someone who makes and sells it UN-oxidized ferrous sulfate someplace.

I do not ever completely dry what ferrous sulfate that I make, it is stored wet, and with just a little sulfuric to keep it acidic and the crystals green, I believe drying it completely, and storing it without the acid as they do in bags or cardboard cans for the ferrous sulfate they sell at garden supply's the air eventually ruins it as true copperas.

Do you run across transformers, if you do take a large one or several small ones, with a hand grinder cut the welds, pull apart the iron laminates, burn off shellack with a propane torch, rinse them and put them in a clean 5 gallon bucket.

I normally use heat on a hot plate and a casserole dish but it should work cold, only taking longer, I normally cut the iron up to smaller pieces, again just so it does not take as long to dissolve.

You could do this in 5 gallon bucket cold taking longer, or buy a used large second hand crock pot dedicate it just for making large volumes of your copperas, dedicating it as the copperas crock.

Add 10% sulfuric acid, when the solution turns green you have your copperas solution, if all of the iron dissolves in your bucket add more iron, as you use up the copperas from your bucket replace it with more dilute sulfuric, if you want to make some crystals for testing gold take a beaker full and crystallize it.

In the copperas crock you could make a large batch, let it heat to dissolve, filter the solution with a strainer and large filter, clean the copperas crock and return filtered solution to let it heat until crystals form , remove crystals from the majority of liquid with a large plastic spoon and bottle them slightly wet add a few drops of fresh acid and put on air tight lid, when this batch has made, refill your copperas crock with some more iron and 10% acid and let it sit on low let it make another batch, it really does not have to be something you have to work at that much, you can let it do most of the work on its own.

Try using #0000 steel wool. It reacts very quickly to the dilute sulfuric acid. I use a 2 liter beaker, drop in 4 pads and fill with slightly diluted battery electolyte. As soon as the steel wool starts to react the bubbles make it float. Fill a 1 liter beaker most of the way with water and set this on top of your steel wool. They will be pushed down into the acid where they can react.

Uljunky:

Won't the oils used to keep the wool rust free if not directly interfere, at least make a mess?

I've taken steel wool and sprayed it down with brake cleaner with a significant runoff of obviously dissolved wax/oil. When dried with a compressed air forced stream, the wool begins to rust almost immediate, the rust accelerating rapidly when exposed to direct sunlight.

Accordingly, since steel wool is such a ready source of finely divided iron (easy/quick to react), I always use some method to remove the protectants. Another method is a strong grease cutter like dawn dishwashing soap in water warm enough to be barely tolerable to the hand. The pad is vigorously squeezed and re-expanded for several minutes, then the pad is flushed under running hot tap water until no evidence of surfactant is seem. Shake, press between paper towels and subject to forced air drying (hair dryer works in a jiffy). If tap water contamination is a concern, you could make the final rinses in distilled water just for piece of mind.

Hope that helps someone, it's standard practice here.

DAS